Functional Movements in Japanese Mini-Basketball Players

PubMed Central

Kuzuhara, Kenji; Shibata, Masashi; Iguchi, Junta; Uchida, Ryo

2018-01-01

Abstract Functional movement screen (FMS) has been used to establish normative data and determine potential injury risk for young adults and athletes, but there are few data in elementary school-age children. The purpose of this study was to establish fundamental values for the FMS in elementary school-age mini-basketball players. Secondary purposes were to examine relationships between functional movement patterns and age, peak height velocity (PHV), and body mass index (BMI), and to compare functional movement patterns between boys and girls and between individuals with and without a history of injury. The mean composite FMS score was 16.5 ± 2.2 (16.5 ± 2.4 for boys, 16.5 ± 1.7 for girls). The composite FMS score was positively correlated with age (r = .312) and negatively correlated with the BMI (r = − .371). However, the FMS score was not correlated with PHV or with PHV age. The FMS score was not different between boys and girls or between individuals who reported a previous injury and those who did not. However, boys in the mini-basketball teams performed better than girls on the trunk stability push-up and rotary stability tests. Age and the body mass index were significantly associated with better and poorer functional movement, respectively. PMID:29599859

Functional Movements in Japanese Mini-Basketball Players.

PubMed

Kuzuhara, Kenji; Shibata, Masashi; Iguchi, Junta; Uchida, Ryo

2018-03-01

Functional movement screen (FMS) has been used to establish normative data and determine potential injury risk for young adults and athletes, but there are few data in elementary school-age children. The purpose of this study was to establish fundamental values for the FMS in elementary school-age mini-basketball players. Secondary purposes were to examine relationships between functional movement patterns and age, peak height velocity (PHV), and body mass index (BMI), and to compare functional movement patterns between boys and girls and between individuals with and without a history of injury. The mean composite FMS score was 16.5 ± 2.2 (16.5 ± 2.4 for boys, 16.5 ± 1.7 for girls). The composite FMS score was positively correlated with age (r = .312) and negatively correlated with the BMI (r = - .371). However, the FMS score was not correlated with PHV or with PHV age. The FMS score was not different between boys and girls or between individuals who reported a previous injury and those who did not. However, boys in the mini-basketball teams performed better than girls on the trunk stability push-up and rotary stability tests. Age and the body mass index were significantly associated with better and poorer functional movement, respectively.

Chess players' eye movements reveal rapid recognition of complex visual patterns: Evidence from a chess-related visual search task.

PubMed

Sheridan, Heather; Reingold, Eyal M

2017-03-01

To explore the perceptual component of chess expertise, we monitored the eye movements of expert and novice chess players during a chess-related visual search task that tested anecdotal reports that a key differentiator of chess skill is the ability to visualize the complex moves of the knight piece. Specifically, chess players viewed an array of four minimized chessboards, and they rapidly searched for the target board that allowed a knight piece to reach a target square in three moves. On each trial, there was only one target board (i.e., the "Yes" board), and for the remaining "lure" boards, the knight's path was blocked on either the first move (the "Easy No" board) or the second move (i.e., "the Difficult No" board). As evidence that chess experts can rapidly differentiate complex chess-related visual patterns, the experts (but not the novices) showed longer first-fixation durations on the "Yes" board relative to the "Difficult No" board. Moreover, as hypothesized, the task strongly differentiated chess skill: Reaction times were more than four times faster for the experts relative to novices, and reaction times were correlated with within-group measures of expertise (i.e., official chess ratings, number of hours of practice). These results indicate that a key component of chess expertise is the ability to rapidly recognize complex visual patterns.

Integration of the functional movement screen into the National Hockey League Combine.

PubMed

Rowan, Chip P; Kuropkat, Christiane; Gumieniak, Robert J; Gledhill, Norman; Jamnik, Veronica K

2015-05-01

The sport of ice hockey requires coordination of complex skills involving musculoskeletal and physiological abilities while simultaneously exposing players to a high risk for injury. The Functional Movement Screen (FMS) was developed to assess fundamental movement patterns that underlie both sport performance and injury risk. The top 111 elite junior hockey players from around the world took part in the 2013 National Hockey League Entry Draft Combine (NHL Combine). The FMS was integrated into the comprehensive medical and physiological fitness evaluations at the request of strength and conditioning coaches with affiliations to NHL teams. The inclusion of the FMS aimed to help develop strategies that could maximize its utility among elite hockey players and to encourage or inform further research in this field. This study evaluated the outcomes of integrating the FMS into the NHL Combine and identified any links to other medical plus physical and physiological fitness assessment outcomes. These potential associations may provide valuable information to identify elements of future training programs that are individualized to athletes' specific needs. The results of the FMS (total score and number of asymmetries identified) were significantly correlated to various body composition measures, aerobic and anaerobic fitness, leg power, timing of recent workouts, and the presence of lingering injury at the time of the NHL Combine. Although statistically significant correlations were observed, the implications of the FMS assessment outcomes remain difficult to quantify until ongoing assessment of FMS patterns, tracking of injuries, and hockey performance are available.

Previously identified patellar tendinopathy risk factors differ between elite and sub-elite volleyball players.

PubMed

Janssen, I; Steele, J R; Munro, B J; Brown, N A T

2015-06-01

Patellar tendinopathy is the most common knee injury incurred in volleyball, with its prevalence in elite athletes more than three times that of their sub-elite counterparts. The purpose of this study was to determine whether patellar tendinopathy risk factors differed between elite and sub-elite male volleyball players. Nine elite and nine sub-elite male volleyball players performed a lateral stop-jump block movement. Maximum vertical jump, training history, muscle extensibility and strength, three-dimensional landing kinematics (250 Hz), along with lower limb neuromuscular activation patterns (1500 Hz), and patellar tendon loading were collected during each trial. Multivariate analyses of variance (P < 0.05) assessed for between-group differences in risk factors or patellar tendon loading. Significant interaction effects were further evaluated using post-hoc univariate analysis of variance tests. Landing kinematics, neuromuscular activation patterns, patellar tendon loading, and most of the previously identified risk factors did not differ between the elite and sub-elite players. However, elite players participated in a higher training volume and had less quadriceps extensibility than sub-elite players. Therefore, high training volume is likely the primary contributor to the injury discrepancy between elite and sub-elite volleyball players. Interventions designed to reduce landing frequency and improve quadriceps extensibility are recommended to reduce patellar tendinopathy prevalence in volleyball players. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Prediction of Lateral Ankle Sprains in Football Players Based on Clinical Tests and Body Mass Index.

PubMed

Gribble, Phillip A; Terada, Masafumi; Beard, Megan Q; Kosik, Kyle B; Lepley, Adam S; McCann, Ryan S; Pietrosimone, Brian G; Thomas, Abbey C

2016-02-01

The lateral ankle sprain (LAS) is the most common injury suffered in sports, especially in football. While suggested in some studies, a predictive role of clinical tests for LAS has not been established. To determine which clinical tests, focused on potentially modifiable factors of movement patterns and body mass index (BMI), could best demonstrate risk of LAS among high school and collegiate football players. Case-control study; Level of evidence, 3. A total of 539 high school and collegiate football players were evaluated during the preseason with the Star Excursion Balance Test (SEBT) and Functional Movement Screen as well as BMI. Results were compared between players who did and did not suffer an LAS during the season. Logistic regression analyses and calculated odds ratios were used to determine which measures predicted risk of LAS. The LAS group performed worse on the SEBT-anterior reaching direction (SEBT-ANT) and had higher BMI as compared with the noninjured group (P < .001). The strongest prediction models corresponded with the SEBT-ANT. Low performance on the SEBT-ANT predicted a risk of LAS in football players. BMI was also significantly higher in football players who sustained an LAS. Identifying clinical tools for successful LAS injury risk prediction will be a critical step toward the creation of effective prevention programs to reduce risk of sustaining an LAS during participation in football. © 2015 The Author(s).

Functional Movement ScreenTM and history of injury in assessment of potential risk of injury among team handball players.

PubMed

Slodownik, Robert; Ogonowska-Slodownik, Anna; Morgulec-Adamowicz, Natalia

2017-09-29

Handball is known to be one of the team sports representing the highest risk of injury. Several investigators have tried to identify injury risk factors in team sports including handball and suggested the need to develop an optimal tool to capture and quantify the potential risk of injury. The aim of the study was to evaluate potential risk of injury among handball players. It was a mixed design study. Handball players from 1st and 2nd division were evaluated (n = 30) using the Functional Movement ScreenTM (FMSTM). Additionally, self-reported history of injury was collected during FMSTM evaluation and after 6 months. Competitive level, training experience, playing position, anthropometric features, symmetry of movement patterns and history of previous injury were analysed while assessing the potential risk of injury. Significant difference between the right and left side (upper limb) was revealed for Shoulder Mobility Test (U = 308.5, p = 0.014). Odds Ratio analysis revealed that having previous injury in the last 12 months is the only statistically significant injury risk factor (OR = 13.71, p = 0.02). Based on this study we can assume that previous injury history reports are crucial in predicting injuries. FMSTM can help in identifying a typical adaptation in throwing shoulder among handball players, but should not be used alone to assess injury risk.

Movement Demands and Metabolic Power Comparisons Between Elite and Subelite Australian Footballers.

PubMed

Johnston, Richard J; Watsford, Mark L; Austin, Damien J; Pine, Matthew J; Spurrs, Robert W

2015-10-01

This study examined the differences in movement demands and metabolic power output of elite and subelite Australian football (AF) players and quantified the movement profiles of a subelite AF competition. Movement variables were collected from AF players using Global Positioning System devices over 2 AF League (elite) and North East Australian Football League (NEAFL, subelite) seasons. A total of 500 files were collected from 37 elite and subelite nomadic AF players. NEAFL players covered 13,547 m at an average speed of 124.5 m·min(-1). Elite players performed more high-speed running (5.7-6.3%) and high acceleration and deceleration efforts (1.9-14.7%, p ≤ 0.05). The elite players had a higher mean metabolic power output (3.2%) and time spent at the very high power zone (15.9%, p ≤ 0.05). In contrast, elite players recorded a lower total match duration than the subelite players (4%, p ≤ 0.05). The contrasting amount of high-intensity activities performed by the 2 groups demonstrates the need to alter the training programs of subelite players to ensure they are capable of meeting the demands of elite football. The differences in match duration suggest that reducing subelite players' match time through increasing their rotations would assist the replication of movement profiles of elite players.

Elite football on artificial turf versus natural grass: movement patterns, technical standards, and player impressions.

PubMed

Andersson, Helena; Ekblom, Björn; Krustrup, Peter

2008-01-15

The aim of the present study was to examine the movement patterns, ball skills, and the impressions of Swedish elite football players during competitive games on artificial turf and natural grass. Time - motion analyses (36 observations) and technical analyses (16 team observations) were performed and 72 male and 21 female players completed a questionnaire. No differences were observed between artificial turf and natural grass in terms of total distance covered (mean 10.19 km, s = 0.19 vs. 10.33 km, s = 0.23), high-intensity running (1.86 km, s = 0.10 vs. 1.87 km, s = 0.14), number of sprints (21, s = 1 vs. 22, s = 2), standing tackles (10, s = 1 vs. 11, s = 1) or headers per game (8, s = 1 vs. 8, s = 1), whereas there were fewer sliding tackles (P < 0.05) on artificial turf than natural grass (2.1, s = 0.5 vs. 4.3, s = 0.6). There were more short passes (218, s = 14 vs. 167, s = 12) and midfield-to-midfield passes (148, s = 11 vs. 107, s = 8) (both P < 0.05) on artificial turf than natural grass. On a scale of 0-10, where 0 = "better than", 5 = "equal to", and 10 = "worse than", the male players reported a negative overall impression (8.3, s = 0.2), poorer ball control (7.3, s = 0.3), and greater physical effort (7.2, s = 0.2) on artificial turf than natural grass. In conclusion, the running activities and technical standard were similar during games on artificial turf and natural grass. However, fewer sliding tackles and more short passes were performed during games on artificial turf. The observed change in playing style could partly explain the male players' negative impression of artificial turf.

Context-dependent player's movement interpretation: application to adaptive game development

NASA Astrophysics Data System (ADS)

Picard, Francois; Estraillier, Pascal

2010-02-01

Video games are more and more controlled by the real movements of the player. However, the player is constrained by the system devices, imposing a limited vocabulary of actions associated with a set of unnatural movements. To introduce more entertaining video games to players, a component-based architecture is proposed. It has been acknowledged as the starting point for the development of adaptive applications based on the hypothesis of a high level dialogue between the system and the player. The system adaptability relies on interpretation mechanisms of the player behaviors. These behaviors are defined through the representation of the real movements of the player who freely interacts with the 3D elements composing an immersive virtual environment, following a given game scenario. The efficient interpretation of the player movements relies on the introduction in the system of the management of the scene's context. The contextual information not only helps to determine the true meaning of an observed behavior but also makes the system to adapt its processes regarding this interpretation, while managing its hardware and software resources efficiently. A commercial motion capture interface has been enhanced by the elaboration of such a system.

CUE USAGE IN VOLLEYBALL: A TIME COURSE COMPARISON OF ELITE, INTERMEDIATE AND NOVICE FEMALE PLAYERS

PubMed Central

Vaeyens, R; Zeuwts, L; Philippaerts, R; Lenoir, M

2014-01-01

This study compared visual search strategies in adult female volleyball players of three levels. Video clips of the attack of the opponent team were presented on a large screen and participants reacted to the final pass before the spike. Reaction time, response accuracy and eye movement patterns were measured. Elite players had the highest response accuracy (97.50 ± 3.5%) compared to the intermediate (91.50 ± 4.7%) and novice players (83.50 ± 17.6%; p<0.05). Novices had a remarkably high range of reaction time but no significant differences were found in comparison to the reaction time of elite and intermediate players. In general, the three groups showed similar gaze behaviour with the apparent use of visual pivots at moments of reception and final pass. This confirms the holistic model of image perception for volleyball and suggests that expert players extract more information from parafoveal regions. PMID:25609887

Construct Validity of Accelerometry-Derived Force to Quantify Basketball Movement Patterns.

PubMed

Staunton, Craig; Wundersitz, Daniel; Gordon, Brett; Kingsley, Michael

2017-12-01

This study assessed the construct validity of accelerometry-derived net force to quantify the external demands of basketball movements. Twenty-eight basketballers completed the Yo-Yo intermittent recovery test (Yo-Yo-IR1) and basketball exercise simulation test (BEST). Intensity was quantified using accelerometry-derived average net force (AvF Net ) and PlayerLoad TM per minute (PL/min). Within-player correlations were determined between intensity and running speed during Yo-Yo-IR1. Measured AvF Net was determined for movements during the BEST and predicted AvF Net was calculated using movement speed and correlations from Yo-Yo-IR1. Relationships between AvF Net and running speed during Yo-Yo-IR1 were nearly perfect (r 2 =0.95, 95% CI: 0.94-0.96; p<0.001) and stronger than correlations between running speed and PL/min (r 2 =0.80, 95% CI: 0.73-0.87; p<0.001). Differences between measured and predicted AvF Net were small during jogging and running (<1%), but large for basketball movements including jumping, change-of-direction and shuffling (15%-41%). As hypothesised, AvF Net differed by playing position (11%-16%; p <0.001) and reflected the additional demand upon players with larger body mass and lower movement efficiency. Both sprint speed and AvF Net reduced during the course of the BEST ( p ≤0.013). These findings confirm the construct validity of AvF Net to quantify the external demand of basketball movements. Accelerometry-derived net force has the potential to quantify the external demands of basketballers during training and competition. © Georg Thieme Verlag KG Stuttgart · New York.

High prevalence of dysfunctional, asymmetrical, and painful movement in elite junior Australian Football players assessed using the Functional Movement Screen.

PubMed

Fuller, Joel T; Chalmers, Samuel; Debenedictis, Thomas A; Townsley, Samuel; Lynagh, Matthew; Gleeson, Cara; Zacharia, Andrew; Thomson, Stuart; Magarey, Mary

2017-02-01

The purpose of this study was to describe the prevalence of dysfunctional, asymmetrical, and painful movement in junior Australian Football players using the Functional Movement Screen (FMS). Cross-sectional study. Elite junior male Australian Football players (n=301) aged 15-18 years completed pre-season FMS testing. The FMS consists of 7 sub-tests: deep squat, hurdle step, in-line lunge, shoulder mobility, active straight leg raise, trunk stability push-up (TSPU) and rotary stability. The shoulder mobility, TSPU, and rotary stability tests were combined with an accompanying clearing test to assess pain. Each sub-test was scored on an ordinal scale from 0 to 3 and summed to give a composite score out of 21. Composite scores ≤14 were operationally defined as indicating dysfunctional movement. Players scoring differently on left and right sides were considered asymmetrical. Players reported whether they missed any games due to injury in the preceding 22 game season. Sixty percent of players (n=182) had composite scores ≤14, 65% of players (n=196) had at least one asymmetrical sub-test, and 38% of players (n=113) had at least one painful sub-test. Forty-two percent of players (n=126) missed at least one game in the previous season due to injury. Previous injury did not influence composite score (p=0.951) or asymmetry (p=0.629). Players reporting an injury during the previous season were more likely to experience pain during FMS testing (odds ratio 1.97, 95% confidence interval 1.23-3.18; p=0.005). Junior Australian Football players demonstrate a high prevalence of dysfunctional, asymmetrical, and painful movement during FMS testing. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

A Weighted Kappa Coefficient for Three Observers as a Measure for Reliability of Expert Ratings on Characteristics in Handball Throwing Patterns

ERIC Educational Resources Information Center

Schorer, Jorg; Weiss, Christel

2007-01-01

Many methods for the identification of key variables in movement patterns have the problem that direct transferability back to coaches or players is not easy; this is because the variables used are not presented in the language of most sport participants. Using a research strategy--from the coaches back to the coaches--proposed by Roth (1996),…

Discriminating Talent Identified Junior Australian Footballers Using a Fundamental Gross Athletic Movement Assessment

PubMed Central

Woods, Carl T.; Banyard, Harry G.; McKeown, Ian; Fransen, Job; Robertson, Sam

2016-01-01

Talent identification (TID) is a pertinent component of the sports sciences, affording practitioners the opportunity to target developmental interventions to a select few; optimising financial investments. However, TID is multi-componential, requiring the recognition of immediate and prospective performance. The measurement of athletic movement skill may afford practitioners insight into the latter component given its augmented relationship with functional sport specific qualities. It is currently unknown whether athletic movement skill is a discriminant quality in junior Australian football (AF). This study aimed to discriminate talent identified junior AF players from their non-talent identified counterparts using a fundamental gross athletic movement assessment. From a total of 50 under 18 (U18) AF players; two groups were classified a priori based on selection level; talent identified (n = 25; state academy representatives) and non-talent identified (n = 25; state-based competition representatives). Players performed a fundamental gross athletic movement assessment based on the Athletic Ability Assessment (AAA), consisting of an overhead squat, double lunge (left and right legs), single leg Romanian deadlift (left and right legs), and a push up (six movement criterions). Movements were scored across three assessment points using a three-point scale (resulting in a possible score of nine for each movement). A multivariate analysis of variance revealed significant between group effects on four of the six movement criterions (d = 0.56 – 0.87; p = 0.01 – 0.02). Binary logistic regression models and a receiver operating characteristic curve inspection revealed that the overhead squat score provided the greatest group discrimination (β(SE) = -0.89(0.44); p < 0.05), with a score of 4.5 classifying 64% and 88% of the talent identified and non-talent identified groups, respectively. Results support the integration of this assessment into contemporary talent identification approaches in junior AF, as it may provide coaches with insight into a juniors developmental potential. Key points On average, talent identified junior AF players possess superior athletic movement qualities relative to their non-talent identified counterparts. The integration of this gross athletic movement assessment into contemporary multidimensional approaches to talent identification may enable insight into a juniors developmental potential. The athletic qualities underpinning the production of the overhead squat movement could augment functional physical qualities in junior Australian footballers. Assessing movement competency in junior contexts may afford practitioners with the opportunity to rectify inefficient fundamental movement patterns prior to entrance into elite senior ranks. PMID:27803635

Rule modification in junior sport: Does it create differences in player movement?

PubMed

Gastin, Paul B; Allan, Matthew D; Bellesini, Kylie; Spittle, Michael

2017-10-01

To determine the effects of rule modification on player movement during matchplay in junior Australian football (AF). Quasi-experimental study design. Time-motion analysis was used to record variables pertaining to player movement including total distance covered, high-speed running (HSR) distance (>14.4km/h) and HSR efforts. GPS data obtained from 145 players (7-12 years) were analysed across four junior AF leagues and three age group combinations (U8/U9, U9/U10 and U11/U12). The four leagues were collapsed into two separate conditions (compliant and non-compliant) based on their adherence to a modified junior sport policy. To control for the influence of age and physical maturity, a secondary analysis was performed on an adequately matched U8 subset of data (n=48). Significant differences (p<0.05) were found between compliant and non-compliant leagues for age and all player movement variables, with participants in the compliant leagues achieving less player movement. Significant differences were also evident between conditions in the U8 subset in total and relative distance and HSR efforts, with moderate to very large differences (29-60%) observed for all player movement variables. Rule modifications limits the extent and intensity of player movement in junior AF compared to standard playing conditions. The unintended effect of reduced physical activity with rule modifications should be compensated for with additional activities wherever possible. League administrators and policy makers should consider the objectives of rule modifications and weigh up both positive and negative outcomes. Copyright © 2017. Published by Elsevier Ltd.

Knee strength ratios in competitive female athletes

PubMed Central

Murawa, Michal; Mackala, Krzysztof; Dworak, Lechoslaw Bogdan

2018-01-01

Knee strength ratios are related to the movement patterns, sport-specific training and knee injuries in athletes. The purpose of this study was to determine the ratios in the concentric isokinetic strength of the hamstrings and quadriceps and the isometric strength of the knee extensors. In female basketball players (n = 14) and female volleyball players (n = 12) were evaluated: the hamstrings to quadriceps peak torque ratio (H/Q) and side-to-side peak torque ratio (TR) for hamstrings and quadriceps; the ratio of the maximal bilateral strength to the summed maximal unilateral strength (B/U) and side-to-side maximal strength ratio (SR) for knee extensors. For the H/Q values, a 2 × 2 × 3 mixed-factorial analysis of variance and Bonferroni post hoc test were computed. The H/Q values increased from 48.0 (3.9)% at 60°/s to 70.4 (7.9)% at 300°/s. Furthermore, there were significant differences in the H/Q values between 300°/s and 180°/s, 300°/s and 60°/s in basketball and volleyball athletes, and between 180°/s and 60°/s only in basketball athletes (p < .05). Significantly higher H/Q results at 60°/s demonstrated basketball players than volleyball players (p < .05). Differences in the TR and SR mean values ranged from 4.4% to 8.6% and indicated no significant side-to-side strength deficits (p > .05). In both groups, greater isometric strength developed bilaterally was found (B/U > 100%). The findings revealed the magnitude of knee strength ratios in female athletes determined by sport-specific movements in basketball and volleyball. This study highlighted the importance of the bilateral strength deficit and muscular balance between the hamstrings and quadriceps in basketball and volleyball athletes in activities related to their movement patterns and specific training. PMID:29315348

Exploring patterns of movement suspension in pedestrian mobility.

PubMed

Orellana, Daniel; Wachowicz, Monica

2011-01-01

One of the main tasks in analyzing pedestrian movement is to detect places where pedestrians stop, as those places usually are associated with specific human activities, and they can allow us to understand pedestrian movement behavior. Very few approaches have been proposed to detect the locations of stops in positioning data sets, and they often are based on selecting the location of candidate stops as well as potential spatial and temporal thresholds according to different application requirements. However, these approaches are not suitable for analyzing the slow movement of pedestrians where the inaccuracy of a nondifferential global positioning system commonly used for movement tracking is so significant that it can hinder the selection of adequate thresholds. In this article, we propose an exploratory statistical approach to detect patterns of movement suspension using a local indicator of spatial association (LISA) in a vector space representation. Two different positioning data sets are used to evaluate our approach in terms of exploring movement suspension patterns that can be related to different landscapes: players of an urban outdoor mobile game and visitors of a natural park. The results of both experiments show that patterns of movement suspension were located at places such as checkpoints in the game and different attractions and facilities in the park. Based on these results, we conclude that using LISA is a reliable approach for exploring movement suspension patterns that represent the places where the movement of pedestrians is temporally suspended by physical restrictions (e.g., checkpoints of a mobile game and the route choosing points of a park).

Distinct cut task strategy in Australian football players with a history of groin pain.

PubMed

Edwards, Suzi; Brooke, Hiram C; Cook, Jill L

2017-01-01

This study aimed to explore the differences in the magnitude of movement variability and strategies utilized during an unanticipated cut task between players with and without a history of groin pain. Cross-sectional design. Biomechanics laboratory. Male Australian football players with (HISTORY; n = 7) or without (CONTROL; n = 10) a history of groin pain. Three-dimensional ground reaction forces (GRF) and kinematics were recorded during 10 successful trials of an unanticipated cut task, and isokinetic hip adduction and abduction strength. Between-group differences were determined using independent-samples t-tests and the coefficient of variation (CV). Key substantial between-group differences identified were that the HISTORY group displayed decreased knee flexion and hip internal rotation, increased knee internal rotation and T12-L1 right rotation, and higher GRFs during the cut task. They also utilized three invariant systems (ankle, knee and T12-L1 joints), while being connected by a segment (hip and L5-S1 joints) that displayed increased lumbopelvic movement during the cut task, and decreased adductor muscle strength. This identifies the need for clinical management of the lower limb and thoracic segment to improve functional movement patterns in athletes with a history of a groin injury. Copyright © 2016 Elsevier Ltd. All rights reserved.

How does knee pain affect trunk and knee motion during badminton forehand lunges?

PubMed

Huang, Ming-Tung; Lee, Hsing-Hsan; Lin, Cheng-Feng; Tsai, Yi-Ju; Liao, Jen-Chieh

2014-01-01

Badminton requires extensive lower extremity movement and a precise coordination of the upper extremity and trunk movements. Accordingly, this study investigated motions of the trunk and the knee, control of dynamic stability and muscle activation patterns of individuals with and without knee pain. Seventeen participants with chronic knee pain and 17 healthy participants participated in the study and performed forehand forward and backward diagonal lunges. This study showed that those with knee pain exhibited smaller knee motions in frontal and horizontal planes during forward lunge but greater knee motions in sagittal plane during backward lunge. By contrast, in both tasks, the injured group showed a smaller value on the activation level of the paraspinal muscles in pre-impact phase, hip-shoulder separation angle, trunk forward inclination range and peak centre of mass (COM) velocity. Badminton players with knee pain adopt a more conservative movement pattern of the knee to minimise recurrence of knee pain. The healthy group exhibit better weight-shifting ability due to a greater control of the trunk and knee muscles. Training programmes for badminton players with knee pain should be designed to improve both the neuromuscular control and muscle strength of the core muscles and the knee extensor with focus on the backward lunge motion.

Three-dimensional kinematics of the lower limbs during forward ice hockey skating.

PubMed

Upjohn, Tegan; Turcotte, René; Pearsall, David J; Loh, Jonathan

2008-05-01

The objectives of the study were to describe lower limb kinematics in three dimensions during the forward skating stride in hockey players and to contrast skating techniques between low- and high-calibre skaters. Participant motions were recorded with four synchronized digital video cameras while wearing reflective marker triads on the thighs, shanks, and skates. Participants skated on a specialized treadmill with a polyethylene slat bed at a self-selected speed for 1 min. Each participant completed three 1-min skating trials separated by 5 min of rest. Joint and limb segment angles were calculated within the local (anatomical) and global reference planes. Similar gross movement patterns and stride rates were observed; however, high-calibre participants showed a greater range and rate of joint motion in both the sagittal and frontal planes, contributing to greater stride length for high-calibre players. Furthermore, consequent postural differences led to greater lateral excursion during the power stroke in high-calibre skaters. In conclusion, specific kinematic differences in both joint and limb segment angle movement patterns were observed between low- and high-calibre skaters.

Time-motion analysis of goalball players in attacks: differences of the player positions and the throwing techniques.

PubMed

Monezi, Lucas Antônio; Magalhães, Thiago Pinguelli; Morato, Márcio Pereira; Mercadante, Luciano Allegretti; Furtado, Otávio Luis Piva da Cunha; Misuta, Milton Shoiti

2018-03-26

In this study, we aimed to analyse goalball players time-motion variables (distance covered, time spent, maximum and average velocities) in official goalball match attacks, taking into account the attack phases (preparation and throwing), player position (centres and wings) and throwing techniques (frontal, spin and between the legs). A total of 365 attacks were assessed using a video based method (2D) through manual tracking using the Dvideo system. Inferential non-parametric statistics were applied for comparison of preparation vs. throwing phase, wings vs. centres and, among the throwing techniques, frontal, spin and between the legs. Significant differences were found between the attack preparation versus the throwing phase for all player time-motion variables: distance covered, time spent, maximum player velocity and average player velocity. Wing players performed most of the throws (85%) and covered longer distances than centres (1.65 vs 0.31 m). The between the legs and the spin throwing techniques presented greater values for most of the time-motion variables (distance covered, time spent and maximum player velocity) than did the frontal technique in both attack phases. These findings provide important information regarding players' movement patterns during goalball matches that can be used to plan more effective training.

A Comparison of Athletic Movement Among Talent-Identified Juniors From Different Football Codes in Australia: Implications for Talent Development.

PubMed

Woods, Carl T; Keller, Brad S; McKeown, Ian; Robertson, Sam

2016-09-01

Woods, CT, Keller, BS, McKeown, I, and Robertson, S. A comparison of athletic movement among talent-identified juniors from different football codes in Australia: implications for talent development. J Strength Cond Res 30(9): 2440-2445, 2016-This study aimed to compare the athletic movement skill of talent-identified (TID) junior Australian Rules football (ARF) and soccer players. The athletic movement skill of 17 TID junior ARF players (17.5-18.3 years) was compared against 17 TID junior soccer players (17.9-18.7 years). Players in both groups were members of an elite junior talent development program within their respective football codes. All players performed an athletic movement assessment that included an overhead squat, double lunge, single-leg Romanian deadlift (both movements performed on right and left legs), a push-up, and a chin-up. Each movement was scored across 3 essential assessment criteria using a 3-point scale. The total score for each movement (maximum of 9) and the overall total score (maximum of 63) were used as the criterion variables for analysis. A multivariate analysis of variance tested the main effect of football code (2 levels) on the criterion variables, whereas a 1-way analysis of variance identified where differences occurred. A significant effect was noted, with the TID junior ARF players outscoring their soccer counterparts when performing the overhead squat and push-up. No other criterions significantly differed according to the main effect. Practitioners should be aware that specific sporting requirements may incur slight differences in athletic movement skill among TID juniors from different football codes. However, given the low athletic movement skill noted in both football codes, developmental coaches should address the underlying movement skill capabilities of juniors when prescribing physical training in both codes.

Expertise and the spatio-temporal characteristics of anticipatory information pick-up from complex movement patterns.

PubMed

Müller, Sean; Abernethy, Bruce; Eid, Michael; McBean, Rohan; Rose, Matthew

2010-01-01

Groups of high- (n = 14), intermediate- (n = 12), and low-skilled (n = 15) cricket batsmen participated in two experiments to examine expertise-related differences in anticipatory information pick-up that combined temporal and spatial occlusion methodologies. In experiment 1 participants were shown video displays of a bowler delivering one of three different types of delivery with the display manipulated so that only selected local features of the bowler's movement pattern (bowling hand, bowling hand and arm, trunk, lower body, or whole body) were visible and then only for specific time periods prior to ball release. Only the highly-skilled players were able to produce better-than-chance predictions of ball type and then only under a limited set of display conditions. Information from bowling hand and arm cues was particularly critical although continuous visibility of these cues was apparently not essential for information pick-up. In experiment 2 the order in which particular features were made visible throughout the bowler's movement pattern was varied in an attempt to find the sequence of cues that was most favourable for effective information pick-up. The necessity in this experiment to switch vision between different features eliminated the highly-skilled players' capability to anticipate. Expert anticipation is dependent on sensitivity to information arising from a select set of local cues, and forced attentional switches between different cues negate effective information pick-up and, with it, the expert advantage.

Ball Machine Usage in Tennis: Movement Initiation and Swing Timing While Returning Balls from a Ball Machine and from a Real Server

PubMed Central

Carboch, Jan; Süss, Vladimir; Kocib, Tomas

2014-01-01

Practicing with the use of a ball machine could handicap a player compared to playing against an actual opponent. Recent studies have shown some differences in swing timing and movement coordination, when a player faces a ball projection machine as opposed to a human opponent. We focused on the time of movement initiation and on stroke timing during returning tennis serves (simulated by a ball machine or by a real server). Receivers’ movements were measured on a tennis court. In spite of using a serving ball speed from 90 kph to 135 kph, results showed significant differences in movement initiation and backswing duration between serves received from a ball machine and serves received from a real server. Players had shorter movement initiation when they faced a ball machine. Backswing duration was longer for the group using a ball machine. That demonstrates different movement timing of tennis returns when players face a ball machine. Use of ball machines in tennis practice should be limited as it may disrupt stroke timing. Key points Players have shorter initial move time when they are facing the ball machine. Using the ball machine results in different swing timing and movement coordination. The use of the ball machine should be limited. PMID:24790483

Ball machine usage in tennis: movement initiation and swing timing while returning balls from a ball machine and from a real server.

PubMed

Carboch, Jan; Süss, Vladimir; Kocib, Tomas

2014-05-01

Practicing with the use of a ball machine could handicap a player compared to playing against an actual opponent. Recent studies have shown some differences in swing timing and movement coordination, when a player faces a ball projection machine as opposed to a human opponent. We focused on the time of movement initiation and on stroke timing during returning tennis serves (simulated by a ball machine or by a real server). Receivers' movements were measured on a tennis court. In spite of using a serving ball speed from 90 kph to 135 kph, results showed significant differences in movement initiation and backswing duration between serves received from a ball machine and serves received from a real server. Players had shorter movement initiation when they faced a ball machine. Backswing duration was longer for the group using a ball machine. That demonstrates different movement timing of tennis returns when players face a ball machine. Use of ball machines in tennis practice should be limited as it may disrupt stroke timing. Key pointsPlayers have shorter initial move time when they are facing the ball machine.Using the ball machine results in different swing timing and movement coordination.The use of the ball machine should be limited.

RELIABILITY OF THE TUCK JUMP INJURY RISK SCREENING ASSESSMENT IN ELITE MALE YOUTH SOCCER PLAYERS

PubMed Central

READ, PAUL; OLIVER, JON L.; DE STE CROIX, MARK B.A.; MYER, GREGORY D.; LLOYD, RHODRI S.

2015-01-01

Altered neuromuscular control has been suggested as a mechanism for injury in soccer players. Ligamentous injuries most often occur during dynamic movements, such as decelerations from jump-landing maneuvers where high risk movement patterns are present. The assessment of kinematic variables during jump-landing tasks as part of a pre-participation screen is useful in the identification of injury risk. An example of a field-based screening tool is the repeated tuck jump assessment. The purpose of this study was to analyze the within-subject variation of the tuck jump screening assessment in elite male youth soccer players. 25 pre and 25 post-peak height velocity (PHV) elite male youth soccer players from the academy of a professional English soccer club completed the assessment. A test, re-test design was used to explore the within-subject inter-session reliability. Technique was graded retrospectively against the 10-point criteria set out in the screening protocol using two-dimensional video cameras. The typical error range reported for tuck jump total score (0.90 – 1.01 in pre and post-PHV players respectively) was considered acceptable. When each criteria was analyzed individually, Kappa coefficient determined that knee valgus was the only criterion to reach substantial agreement across the two test sessions for both groups. The results of this study suggest that although tuck jump total score may be reliably assessed in elite male youth soccer players, caution should be applied in solely interpreting the composite score due to the high within-subject variation in a number of the individual criteria. Knee valgus may be reliably used to screen elite youth male soccer players for this plyometric technique error and for test, re-test comparison. PMID:26562715

Normative data for the Functional Movement Screen in male Gaelic field sports.

PubMed

Fox, Domhnaill; O'Malley, Edwenia; Blake, Catherine

2014-08-01

To determine normative values for the Functional Movement Screen (FMS) in Elite and Sub-Elite male Gaelic Football and Hurling players. A cross sectional study of functional movement in Gaelic games at Elite and Sub-Elite level. Players were video recorded completing the Functional Movement Screen Tool and scored post-test. Comparisons were analysed using Mann-Whitney U tests. Field testing in team gym facility and university biomechanics laboratory. A total of 62 players were tested. This consisted of 41 Hurling, and 21 Gaelic Football players. 30 of these participants were deemed Elite and 32 were deemed Sub-Elite. The mean age of the sample was 22.15 ± 3.02 years. Functional Movement Screen (FMS). The FMS mean score for the sample was 15.56 ± 1.46. The Elite group (15.8 ± 1.58) scored higher than the Sub-Elite group (15.34 ± 1.31) but there was no significant difference between groups. This study provides normative reference values for Gaelic Players. Elite Gaelic Players perform no better than a young, active population in the FMS indicating a potential problem with the FMS as a measure. Copyright © 2013 Elsevier Ltd. All rights reserved.

Positional demands of international rugby union: evaluation of player actions and movements.

PubMed

Quarrie, Kenneth L; Hopkins, Will G; Anthony, Mike J; Gill, Nicholas D

2013-07-01

In rugby union, published analyses of actions and movements of players during matches have been limited to small samples of games at regional or national level. To analyse movements and activities of players in international rugby union matches with a sample size sufficient to clearly delineate positional roles. Observational study. Actions of 763 players were coded from video recordings of 90 international matches played by the New Zealand national team (the All Blacks) from 2004 to 2010. Movements of players were coded for 27 of these matches via a semi-automated player-tracking system. Movements and activities of all players from both teams were coded. Cluster analysis of activities and time-motion variables produced five subgroups of forwards (props, hookers, locks, flankers, Number 8 forwards) and five subgroups of backs (scrum-half, fly-half, midfield backs, wings and fullbacks). Forwards sustained much higher contact loads per match than backs, via scrums, rucks, tackles and mauls. Mean distance covered per match ranged from 5400 to 6300m, with backs generally running further than forwards. There were marked differences between positional groups in the amount of distance covered at various speeds. The amount of play per match varies by position due to differences in rates at which players are substituted. The distance covered by players at relatively fast running speeds (in excess of 5ms(-1)) appears to be higher during international matches than when competing at lower levels of the professional game. The specific match demands for positional groups need to be considered when managing player workloads. Copyright © 2012 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Movement variability and skill level of various throwing techniques.

PubMed

Wagner, Herbert; Pfusterschmied, Jürgen; Klous, Miriam; von Duvillard, Serge P; Müller, Erich

2012-02-01

In team-handball, skilled athletes are able to adapt to different game situations that may lead to differences in movement variability. Whether movement variability affects the performance of a team-handball throw and is affected by different skill levels or throwing techniques has not yet been demonstrated. Consequently, the aims of the study were to determine differences in performance and movement variability for several throwing techniques in different phases of the throwing movement, and of different skill levels. Twenty-four team-handball players of different skill levels (n=8) performed 30 throws using various throwing techniques. Upper body kinematics was measured via an 8 camera Vicon motion capture system and movement variability was calculated. Results indicated an increase in movement variability in the distal joint movements during the acceleration phase. In addition, there was a decrease in movement variability in highly skilled and skilled players in the standing throw with run-up, which indicated an increase in the ball release speed, which was highest when using this throwing technique. We assert that team-handball players had the ability to compensate an increase in movement variability in the acceleration phase to throw accurately, and skilled players were able to control the movement, although movement variability decreased in the standing throw with run-up. Copyright © 2011 Elsevier B.V. All rights reserved.

Physiological, movement and technical demands of centre-wicket Battlezone, traditional net-based training and one-day cricket matches: a comparative study of sub-elite cricket players.

PubMed

Vickery, Will; Dascombe, Ben; Duffield, Rob

2014-01-01

This study compared physiological, physical and technical demands of Battlezone, traditional cricket training and one-day matches. Data were initially collected from 11 amateur, male cricket players (age: 22.2 ± 3.3 year, height: 1.82 ± 0.06 m body mass: 80.4 ± 9.8 kg) during four Battlezone and four traditional cricket training sessions encompassing different playing positions. Heart rate, blood lactate concentration, rating of perceived exertion and movement patterns of players were measured. Retrospective video analysis was performed to code for technical outcomes. Similar data were collected from 42 amateur, male cricket players (23.5 ± 4.7 year, 1.81 ± 0.07 m, 81.4 ± 11.4 kg) during one-day matches. Significant differences were found between Battlezone, traditional cricket training and one-day matches within each playing position. Specifically, Battlezone invoked the greatest physiological and physical demands from batsmen in comparison to traditional cricket training and one-day matches. However, the greatest technical demand for batsmen was observed during traditional cricket training. In regards to the other playing positions, a greater physiological, physical and technical demand was observed during Battlezone and traditional training than during one-day matches. These results suggest that the use of Battlezone and traditional cricket training provides players with a suitable training stimulus for replicating the physiological, physical and technical demands of one-day cricket.

Distinct eye movement patterns enhance dynamic visual acuity.

PubMed

Palidis, Dimitrios J; Wyder-Hodge, Pearson A; Fooken, Jolande; Spering, Miriam

2017-01-01

Dynamic visual acuity (DVA) is the ability to resolve fine spatial detail in dynamic objects during head fixation, or in static objects during head or body rotation. This ability is important for many activities such as ball sports, and a close relation has been shown between DVA and sports expertise. DVA tasks involve eye movements, yet, it is unclear which aspects of eye movements contribute to successful performance. Here we examined the relation between DVA and the kinematics of smooth pursuit and saccadic eye movements in a cohort of 23 varsity baseball players. In a computerized dynamic-object DVA test, observers reported the location of the gap in a small Landolt-C ring moving at various speeds while eye movements were recorded. Smooth pursuit kinematics-eye latency, acceleration, velocity gain, position error-and the direction and amplitude of saccadic eye movements were linked to perceptual performance. Results reveal that distinct eye movement patterns-minimizing eye position error, tracking smoothly, and inhibiting reverse saccades-were related to dynamic visual acuity. The close link between eye movement quality and DVA performance has important implications for the development of perceptual training programs to improve DVA.

Dynamic knee stability and ballistic knee movement after ACL reconstruction: an application on instep soccer kick.

PubMed

Cordeiro, Nuno; Cortes, Nelson; Fernandes, Orlando; Diniz, Ana; Pezarat-Correia, Pedro

2015-04-01

The instep soccer kick is a pre-programmed ballistic movement with a typical agonist-antagonist coordination pattern. The coordination pattern of the kick can provide insight into deficient neuromuscular control. The purpose of this study was to investigate knee kinematics and hamstrings/quadriceps coordination pattern during the knee ballistic extension phase of the instep kick in soccer players after anterior cruciate ligament reconstruction (ACL reconstruction). Seventeen players from the Portuguese Soccer League participated in this study. Eight ACL-reconstructed athletes (experimental group) and 9 healthy individuals (control group) performed three instep kicks. Knee kinematics (flexion and extension angles at football contact and maximum velocity instants) were calculated during the kicks. Rectus femoris (RF), vastus lateralis, vastus medialis, biceps femoralis, and semitendinosus muscle activations were quantified during the knee extension phase. The ACL-reconstructed group had significantly lower knee extension angle (-1.2 ± 1.6, p < 0.021) and increased variability (1.1 ± 1.2, p < 0.012) when compared with the control group. Within the EMG variables, the RF had a significantly greater activity in the ACL-reconstructed group than in the control group (79.9 ± 27.7 % MVC vs. 49.2 ± 20.8 % MVC, respectively, p < 0.034). No other statistically significant differences were found. The findings of this study demonstrate that changes in ACL-reconstructed individuals were observed on knee extension angle and RF muscle activation while performing an instep kick. These findings are in accordance with the knee stability recovery process after ACL reconstruction. No differences were observed in the ballistic control movement pattern between normal and ACL-reconstructed subjects. Performing open kinetic chain exercises using ballistic movements can be beneficial when recovering from ACL reconstruction. The exercises should focus on achieving multi-joint coordination and full knee extension (range of motion). III.

Functional Performance Among Active Female Soccer Players After Unilateral Primary Anterior Cruciate Ligament Reconstruction Compared With Knee-Healthy Controls.

PubMed

Fältström, Anne; Hägglund, Martin; Kvist, Joanna

2017-02-01

Good functional performance with limb symmetry is believed to be important to minimize the risk of injury after a return to pivoting and contact sports after anterior cruciate ligament reconstruction (ACLR). This study aimed to investigate any side-to-side limb differences in functional performance and movement asymmetries in female soccer players with a primary unilateral anterior cruciate ligament (ACL)-reconstructed knee and to compare these players with knee-healthy controls from the same soccer teams. Cross-sectional study; Level of evidence, 3. This study included 77 active female soccer players at a median of 18 months after ACLR (interquartile range [IQR], 14.5 months; range, 7-39 months) and 77 knee-healthy female soccer players. The mean age was 20.1 ± 2.3 years for players with an ACL-reconstructed knee and 19.5 ± 2.2 years for controls. We used a battery of tests to assess postural control (Star Excursion Balance Test) and hop performance (1-legged hop for distance, 5-jump test, and side hop). Movement asymmetries in the lower limbs and trunk were assessed with the drop vertical jump and the tuck jump using 2-dimensional analyses. The reconstructed and uninvolved limbs did not differ in any of the tests. In the 5-jump test, players with an ACL-reconstructed knee performed worse than controls (mean 8.75 ± 1.05 m vs 9.09 ± 0.89 m; P = .034). On the drop vertical jump test, the ACL-reconstructed limb had significantly less knee valgus motion in the frontal plane (median 0.028 m [IQR, 0.049 m] vs 0.045 m [IQR, 0.043 m]; P = .004) and a lower probability of a high knee abduction moment (pKAM) (median 69.2% [IQR, 44.4%] vs 79.8% [IQR, 44.8%]; P = .043) compared with the control players' matched limb (for leg dominance). Results showed that 9% to 49% of players in both groups performed outside recommended guidelines on the different tests. Only 14 players with an ACL-reconstructed knee (18%) and 15 controls (19%) had results that met the recommended guidelines for all 5 tests ( P = .837). The reconstructed and uninvolved limbs did not differ, and players with an ACL-reconstructed knee and controls differed only minimally on the functional performance tests, indicating similar function. It is worth noting that many players with an ACL-reconstructed knee and controls had movement asymmetries and a high pKAM pattern, which have previously been associated with an increased risk for both primary and secondary ACL injury in female athletes.

Reliability of the Tuck Jump Injury Risk Screening Assessment in Elite Male Youth Soccer Players.

PubMed

Read, Paul J; Oliver, Jon L; de Ste Croix, Mark B A; Myer, Gregory D; Lloyd, Rhodri S

2016-06-01

Read, PJ, Oliver, JL, de Ste Croix, MBA, Myer, GD, and Lloyd, RS. Reliability of the tuck jump injury risk screening assessment in elite male youth soccer players. J Strength Cond Res 30(6): 1510-1516, 2016-Altered neuromuscular control has been suggested as a mechanism for injury in soccer players. Ligamentous injuries most often occur during dynamic movements, such as decelerations from jump-landing maneuvers where high-risk movement patterns are present. The assessment of kinematic variables during jump-landing tasks as part of a preparticipation screen is useful in the identification of injury risk. An example of a field-based screening tool is the repeated tuck jump assessment. The purpose of this study was to analyze the within-subject variation of the tuck jump screening assessment in elite male youth soccer players. Twenty-five pre-peak height velocity (PHV) and 25 post-PHV elite male youth soccer players from the academy of a professional English soccer club completed the assessment. A test-retest design was used to explore the within-subject intersession reliability. Technique was graded retrospectively against the 10-point criteria set out in the screening protocol using two-dimensional video cameras. The typical error range reported for tuck jump total score (0.90-1.01 in pre-PHV and post-PHV players respectively) was considered acceptable. When each criteria was analyzed individually, kappa coefficient determined that knee valgus was the only criterion to reach substantial agreement across the two test sessions for both groups. The results of this study suggest that although tuck jump total score may be reliably assessed in elite male youth soccer players, caution should be applied in solely interpreting the composite score due to the high within-subject variation in a number of the individual criteria. Knee valgus may be reliably used to screen elite youth male soccer players for this plyometric technique error and for test-retest comparison.

Agreement Between Visual Assessment and 2-Dimensional Analysis During Jump Landing Among Healthy Female Athletes.

PubMed

Rabin, Alon; Einstein, Ofira; Kozol, Zvi

2018-04-01

  Altered movement patterns, including increased frontal-plane knee movement and decreased sagittal-plane hip and knee movement, have been associated with several knee disorders. Nevertheless, the ability of clinicians to visually detect such altered movement patterns during high-speed athletic tasks is relatively unknown.   To explore the association between visual assessment and 2-dimensional (2D) analysis of frontal-plane knee movement and sagittal-plane hip and knee movement during a jump-landing task among healthy female athletes.   Cross-sectional study.   Gymnasiums of participating volleyball teams.   A total of 39 healthy female volleyball players (age = 21.0 ± 5.2 years, height = 172.0 ± 8.6 cm, mass = 64.2 ± 7.2 kg) from Divisions I and II of the Israeli Volleyball Association.   Frontal-plane knee movement and sagittal-plane hip and knee movement during jump landing were visually rated as good, moderate, or poor based on previously established criteria. Frontal-plane knee excursion and sagittal-plane hip and knee excursions were measured using free motion-analysis software and compared among athletes with different visual ratings of the corresponding movements.   Participants with different visual ratings of frontal-plane knee movement displayed differences in 2D frontal-plane knee excursion ( P < .01), whereas participants with different visual ratings of sagittal-plane hip and knee movement displayed differences in 2D sagittal-plane hip and knee excursions ( P < .01).   Visual ratings of frontal-plane knee movement and sagittal-plane hip and knee movement were associated with differences in the corresponding 2D hip and knee excursions. Visual rating of these movements may serve as an initial screening tool for detecting altered movement patterns during jump landings.

Mechanisms of anterior cruciate ligament injuries in elite women's netball: a systematic video analysis.

PubMed

Stuelcken, Max C; Mellifont, Daniel B; Gorman, Adam D; Sayers, Mark G L

2016-08-01

This study involved a systematic video analysis of 16 anterior cruciate ligament (ACL) injuries sustained by elite-level netball players during televised games in order to describe the game situation, the movement patterns involved, the player's behaviour, and a potential injury mechanism. Eight of the ACL injuries were classified as "indirect contact" and eight as "non-contact". Two common scenarios were identified. In Scenario A the player was jumping to receive or intercept a pass and whilst competing for the ball experienced a perturbation in the air. As a result the player's landing was unbalanced with loading occurring predominantly on the knee of the injured side. In Scenario B the player was generally in a good position at ground contact, but then noticeably altered the alignment of the trunk before the landing was completed. This involved rotating and laterally flexing the trunk without altering the alignment of the feet. Apparent knee valgus collapse on the knee of the injured side was observed in 3/6 Scenario A cases and 5/6 Scenario B cases. Players may benefit from landing training programmes that incorporate tasks that use a ball and include decision-making components or require players to learn to cope with being unbalanced.

Looking to Score: The Dissociation of Goal Influence on Eye Movement and Meta-Attentional Allocation in a Complex Dynamic Natural Scene

PubMed Central

Taya, Shuichiro; Windridge, David; Osman, Magda

2012-01-01

Several studies have reported that task instructions influence eye-movement behavior during static image observation. In contrast, during dynamic scene observation we show that while the specificity of the goal of a task influences observers’ beliefs about where they look, the goal does not in turn influence eye-movement patterns. In our study observers watched short video clips of a single tennis match and were asked to make subjective judgments about the allocation of visual attention to the items presented in the clip (e.g., ball, players, court lines, and umpire). However, before attending to the clips, observers were either told to simply watch clips (non-specific goal), or they were told to watch the clips with a view to judging which of the two tennis players was awarded the point (specific goal). The results of subjective reports suggest that observers believed that they allocated their attention more to goal-related items (e.g. court lines) if they performed the goal-specific task. However, we did not find the effect of goal specificity on major eye-movement parameters (i.e., saccadic amplitudes, inter-saccadic intervals, and gaze coherence). We conclude that the specificity of a task goal can alter observer’s beliefs about their attention allocation strategy, but such task-driven meta-attentional modulation does not necessarily correlate with eye-movement behavior. PMID:22768058

Morphological, motor and situation-motor characteristics of elite female handball players according to playing performance and position.

PubMed

Cavala, Marijana; Katić, Ratko

2010-12-01

The aim of the study was to define biomotor characteristics that determine playing performance and position in female handball. A battery of 13 variables consisting of somatotype components (3 variables), basic motor abilities (5 variables) and specific motor abilities (5 variables) were applied in a sample of 52 elite female handball players. Differences in biomotor characteristics according to playing performance and position of female handball players were determined by use of the analysis of variance (ANOVA) and discriminative analysis. Study results showed the high-quality female handball players to predominantly differ from the less successful ones in the specific factor of throw strength and basic dash factor, followed by the specific abilities of movement without and with ball, basic coordination/agility and specific ability of ball manipulation, and a more pronounced mesomorphic component. Results also revealed the wing players to be superior in the speed of movement frequency (psychomotor speed), run (explosive strength) and speed of movement with ball as compared with players at other playing positions. Also, endomorphic component was less pronounced in players at the wing and back player positions as compared with goalkeeper and pivot positions, where endomorphic component was considerably more pronounced.

Knee movement patterns of injured and uninjured adolescent basketball players when landing from a jump: A case-control study

PubMed Central

Louw, Quinette; Grimmer, Karen; Vaughan, Christopher

2006-01-01

Background A common knee injury mechanism sustained during basketball is landing badly from a jump. Landing is a complex task and requires good coordination, dynamic muscle control and flexibility. For adolescents whose coordination and motor control has not fully matured, landing badly from a jump can present a significant risk for injury. There is currently limited biomechanical information regarding the lower limb kinetics of adolescents when jumping, specifically regarding jump kinematics comparing injured with uninjured adolescents. This study reports on an investigation of biomechanical differences in landing patterns of uninjured and injured adolescent basketball players. Methods A matched case-control study design was employed. Twenty-two basketball players aged 14–16 years participated in the study: eleven previously knee-injured and eleven uninjured players matched with cases for age, gender, weight, height and years of play, and playing for the same club. Six high-speed, three-dimensional Vicon 370 cameras (120 Hz), Vicon biomechanical software and SAS Version 8 software were employed to analyse landing patterns when subjects performed a "jump shot". Linear correlations determined functional relationships between the biomechanical performance of lower limb joints, and paired t-tests determined differences between the normalised peak biomechanical parameters. Results The average peak vertical ground reaction forces between the cases and controls were similar. The average peak ground reaction forces between the cases and controls were moderately correlated (r = -0.47). The control (uninjured) players had significantly greater hip and knee flexion angles and significantly greater eccentric activity on landing than the uninjured cases (p < 0.01). Conclusion The findings of the study indicate that players with a history of knee injuries had biomechanically compromised landing techniques when compared with uninjured players matched for gender, age and club. Descriptions (norms) of expected levels of knee control, proprioceptive acuity and eccentric strength relative to landing from a jump, at different ages and physical developmental stages, would assist clinicians and coaches to identify players with inappropriate knee performance comparable to their age or developmental stage. PMID:16522210

Comparison of global positioning and computer-based tracking systems for measuring player movement distance during Australian football.

PubMed

Edgecomb, S J; Norton, K I

2006-05-01

Sports scientists require a thorough understanding of the energy demands of sports and physical activities so that optimal training strategies and game simulations can be constructed. A range of techniques has been used to both directly assess and estimate the physiological and biochemical changes during competition. A fundamental approach to understanding the contribution of the energy systems in physical activity has involved the use of time-motion studies. A number of tools have been used from simple pen and paper methods, the use of video recordings, to sophisticated electronic tracking devices. Depending on the sport, there may be difficulties in using electronic tracking devices because of concerns of player safety. This paper assesses two methods currently used to measure player movement patterns during competition: (1) global positioning technology (GPS) and (2) a computer-based tracking (CBT) system that relies on a calibrated miniaturised playing field and mechanical movements of the tracker. A range of ways was used to determine the validity and reliability of these methods for tracking Australian footballers for distance covered during games. Comparisons were also made between these methods. The results indicate distances measured using CBT overestimated the actual values (measured with a calibrated trundle wheel) by an average of about 5.8%. The GPS system overestimated the actual values by about 4.8%. Distances measured using CBT in experienced hands were as accurate as the GPS technology. Both systems showed relatively small errors in true distances.

Social network analysis of cattle movement in Kampong Cham, Kampong Speu and Takeo, Cambodia.

PubMed

Poolkhet, C; Kasemsuwan, S; Seng, S; Keartha, C; Sokmao, C; Shin, M; Kalpravidh, W; Hinrichs, J

2016-07-01

The aim of this study is to provide insight the network of cattle movement in Kampong Cham, Kampong Speu and Takeo, Cambodia. A cross-sectional study was carried out from July 2014 to August 2014, using questionnaires. It was implemented with 435 interviewees (24.4%, 24.6% and 51.0% from Kampong Cham, Kampong Speu and Takeo, respectively) using one-step snowball sampling. The findings suggest that the key players in all three provinces are producers who raise their cattle as backyard animals. In all three provinces the key players in spreading disease are probably the middlemen, collectors, brokers or traders. The network of cattle movement is presented as a strong component of varying size in each location. In this network we found three cut-points in both Kampong Cham and Kampong Speu. The network in each province indicates a random pattern of node distribution. The results of our study are useful to relevant authorities and researchers to understand the spread of infectious diseases into different areas. The middlemen, collectors, brokers and traders need to be controlled as first priority in order to reduce the magnitude of the spread of disease. Copyright © 2016 Elsevier B.V. All rights reserved.

The Effect of Eight Weeks Plyometric Training on Anaerobic Power, Counter Movement Jumping and Isokinetic Strength in 15-18 Years Basketball Players

ERIC Educational Resources Information Center

Adigüzel, Niyazi Sidki; Günay, Mehmet

2016-01-01

The purpose of this study was to investigate the effect of eight weeks plyometric training on anaerobic power, counter movement jumping and isokinetic strength in 15-18 years aged basketball players. This study was including 30 male Basketball players. The subjects were divided into two groups as: the experimental group (n = 15) and the control…

Increased plantar force and impulse in American football players with high arch compared to normal arch

PubMed Central

Carson, Daniel W.; Myer, Gregory D.; Hewett, Timothy E.; Heidt, Robert S.; Ford, Kevin R.

2014-01-01

Background Risk of overuse injury among athletes is high due in part to repeated loading of the lower extremities. Compared to individuals with normal arch (NA) structure, those with high (HA) or low arch (LA) may be at increased risk of specific overuse injuries, including stress fractures. A high medial longitudinal arch may result in decreased shock absorbing properties due to increased rigidity in foot mechanics. While the effect of arch structure on dynamic function has been examined in straight line walking and running, the relationship between the two during multi-directional movements remains unstudied. Objective The purpose of this study was to determine if differences in plantar loading in football players occur during both walking and pivoting movements. Method Plantar loading was examined in 9 regions of the foot for 26 participants (16 NA, 10 HA). Results High arch athletes demonstrated increased maximum force in the lateral rear foot and medial forefoot, and force time integral in the medial forefoot while walking. HA athletes also demonstrated increased maximum force in the medial rear foot and medial and central forefoot during rapid pivoting. Conclusions The current findings demonstrate that loading patterns differ between football players with high and normal arch structure, which could possibly influence injury risk in this population. PMID:23141809

A review of vision-based motion analysis in sport.

PubMed

Barris, Sian; Button, Chris

2008-01-01

Efforts at player motion tracking have traditionally involved a range of data collection techniques from live observation to post-event video analysis where player movement patterns are manually recorded and categorized to determine performance effectiveness. Due to the considerable time required to manually collect and analyse such data, research has tended to focus only on small numbers of players within predefined playing areas. Whilst notational analysis is a convenient, practical and typically inexpensive technique, the validity and reliability of the process can vary depending on a number of factors, including how many observers are used, their experience, and the quality of their viewing perspective. Undoubtedly the application of automated tracking technology to team sports has been hampered because of inadequate video and computational facilities available at sports venues. However, the complex nature of movement inherent to many physical activities also represents a significant hurdle to overcome. Athletes tend to exhibit quick and agile movements, with many unpredictable changes in direction and also frequent collisions with other players. Each of these characteristics of player behaviour violate the assumptions of smooth movement on which computer tracking algorithms are typically based. Systems such as TRAKUS, SoccerMan, TRAKPERFORMANCE, Pfinder and Prozone all provide extrinsic feedback information to coaches and athletes. However, commercial tracking systems still require a fair amount of operator intervention to process the data after capture and are often limited by the restricted capture environments that can be used and the necessity for individuals to wear tracking devices. Whilst some online tracking systems alleviate the requirements of manual tracking, to our knowledge a completely automated system suitable for sports performance is not yet commercially available. Automatic motion tracking has been used successfully in other domains outside of elite sport performance, notably for surveillance in the military and security industry where automatic recognition of moving objects is achievable because identification of the objects is not necessary. The current challenge is to obtain appropriate video sequences that can robustly identify and label people over time, in a cluttered environment containing multiple interacting people. This problem is often compounded by the quality of video capture, the relative size and occlusion frequency of people, and also changes in illumination. Potential applications of an automated motion detection system are offered, such as: planning tactics and strategies; measuring team organisation; providing meaningful kinematic feedback; and objective measures of intervention effectiveness in team sports, which could benefit coaches, players, and sports scientists.

A Critical Interpersonal Distance Switches between Two Coordination Modes in Kendo Matches

PubMed Central

Okumura, Motoki; Kijima, Akifumi; Kadota, Koji; Yokoyama, Keiko; Suzuki, Hiroo; Yamamoto, Yuji

2012-01-01

In many competitive sports, players need to quickly and continuously execute movements that co-adapt to various movements executed by their opponents and physical objects. In a martial art such as kendo, players must be able to skillfully change interpersonal distance in order to win. However, very little information about the task and expertise properties of the maneuvers affecting interpersonal distance is available. This study investigated behavioral dynamics underlying opponent tasks by analyzing changes in interpersonal distance made by expert players in kendo matches. Analysis of preferred interpersonal distances indicated that players tended to step toward and away from their opponents based on two distances. The most preferred distance enabled the players to execute both striking and defensive movements immediately. The relative phase analysis of the velocities at which players executed steps toward and away revealed that players developed anti-phase synchronizations at near distances to maintain safe distances from their opponents. Alternatively, players shifted to in-phase synchronization to approach their opponents from far distances. This abrupt phase-transition phenomenon constitutes a characteristic bifurcation dynamics that regularly and instantaneously occurs between in- and anti-phase synchronizations at a critical interpersonal distance. These dynamics are profoundly affected by the task constraints of kendo and the physical constraints of the players. Thus, the current study identifies the clear behavioral dynamics that emerge in a sport setting. PMID:23284799

Performance and Kinematics of Various Throwing Techniques in Team-Handball

PubMed Central

Wagner, Herbert; Pfusterschmied, Jürgen; von Duvillard, Serge P.; Müller, Erich

2011-01-01

In team-handball competition, the players utilize various throwing techniques that differ in the lower body movements (with and without run-up or jump). These different lower body movements influence changes in the upper body movements and thus also affect the performance. A comprehensive analysis of 3D-kinematics of team-handball throws that may explain these differences in performance is lacking. Consequently, the purpose of this study was (1) to compare performance (ball velocity and throwing accuracy) between the jump throw, standing throw with and without run-up, and the pivot throw; (2) to calculate the influence of kinematic parameters to ball velocity; and (3) to determine if these four throwing techniques differ significantly in kinematics. Three-dimensional kinematic data (angles, angular velocities and their timing, ball velocity and velocity of the center of mass) of 14 elite team-handball players were measured using an 8 camera Vicon MX13 motion capture system (Vicon, Oxford, UK), at 250 Hz. Significant difference was found between the four throwing techniques for ball velocity (p < 0. 001), maximal velocity of the center of mass in goal-directed movement (p < 0.001), and 15 additional kinematic variables (p < 0.003). Ball velocity was significant impacted by the run-up and the pelvis and trunk movements. Depending on floor contact (standing vs. jump throws), elite players in the study used two different strategies (lead leg braces the body vs. opposed leg movements during flight) to accelerate the pelvis and trunk to yield differences in ball velocity. However, these players were able to utilize the throwing arm similarly in all four throwing techniques. Key points Elite team-handball players achieved the greatest ball velocity in the standing throw with run-up (100%), followed by the standing throw without run-up (93%), jump throw (92%) and pivot throw (85%). Depending on the floor contact (standing vs. jump throws) the elite players of the study used two different strategies (lead leg braces the body vs. opposed leg movements during flight) to accelerate the pelvis and trunk that caused differences in ball velocity. Elite team-handball players were able to utilize the throwing arm similarly in all four throwing techniques. PMID:24149298

Maturational effect on Functional Movement Screen™ score in adolescent soccer players.

PubMed

Portas, Matthew David; Parkin, Guy; Roberts, James; Batterham, Alan Mark

2016-10-01

The effect of maturity on Functional Movement Screen (FMS) scores in elite, adolescent soccer players was examined. A cross-sectional observational study was completed. Participants were 1163 male English Football League soccer players (age 8-18 years). Players were mid-foundation phase (MF) (U9); late foundation phase (LF) (U10 and U11); early youth development phase (EYD) (U12 and U13); mid-youth development (MYD) phase (U14-U15); Late Youth Development Phase (LYD) (U16) and early professional development phase (EPD) (U18). Age from peak height velocity was estimated and players were categorized as pre- or post-peak height velocity (PHV). To analyse where differences in FMStotal score existed we separated the screen into FMSmove (3 movement tests); FMSflex (2 mobility tests) and FMSstab (2 stability tests). FMStotal median score ranged from 11 at MF to 14 for EPD. There was a substantial increase (10%) in those able to achieve a score of ≥14 on FMStotal in those who were post-PHV compared to pre-PHV. This was explained by a substantial increase in those achieving a score of ≥4 on FMSstab (21%). There was a substantial increase in the proportion of players who achieved the FMStotal threshold of ≥14 with an increase of 47.5 (41.4-53.6)% from the MF phase to the EPD phase due to improvements in FMSmove and FMSstab. PHV and maturity have substantial effects on FMS performance. FMS assessment appears to be invalid for very young players. Findings are relevant to those analyzing movement in soccer players. Copyright © 2015 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

The movement characteristics of English Premiership rugby union players.

PubMed

Cahill, Nicola; Lamb, Kevin; Worsfold, Paul; Headey, Roy; Murray, Stafford

2013-01-01

The purpose of this investigation was to quantify the movement characteristics of elite rugby union players during competitive play and identify whether position-related differences exist. Ninety-eight elite players from eight English Premiership Clubs were tracked using global positioning systems (GPS) during 44 competitive matches throughout the 2010/2011 season. Player positions were defined as: (1) backs or forwards; (2) front, second and back rows, scrum half, inside and outside backs; (3) 15 individual positions (numbers 1-15). Analysis revealed the game is predominantly played at low speeds with little distance covered 'sprinting' by either the backs (50 ± 76 m) or the forwards (37 ± 64 m). The backs travelled greater (P < 0.05) absolute and relative distances than the forwards. The scrum half covered the greatest total distance during a match (7098 ± 778 m) and the front row the least (5158 ± 200 m). The back row covered the greatest distances at 'sprinting' speeds, particularly the number 8 position (77 m). These findings reflect notable differences in the movement characteristics displayed by elite rugby union players in specific positional roles, and reinforce the contemporary view that training programmes for such players ought to be structured with this in mind.

Designing for movement quality in exergames: lessons learned from observing senior citizens playing stepping games.

PubMed

Skjæret, Nina; Nawaz, Ather; Ystmark, Kristine; Dahl, Yngve; Helbostad, Jorunn L; Svanæs, Dag; Vereijken, Beatrix

2015-01-01

Exergames are increasingly used as an exercise intervention to reduce fall risk in elderly. However, few exergames have been designed specifically for elderly, and we lack knowledge about the characteristics of the movements elicited by exergames and thereby about their potential to train functions important for fall risk reduction. This study investigates game elements and older players' movement characteristics during stepping exergames in order to inform exergame design for movement quality in the context of fall preventive exercise. Fourteen senior citizens (mean age 73 years ± 5.7, range 65 - 85) played 3 stepping exergames in a laboratory. Each of the exergames was described with respect to 7 game elements (physical space, sensing hardware technology, game graphics and sound, model of user, avatar/mapping of movements, game mechanism and game narrative). Five movement characteristics (weight shift; variation in step length, speed, and movement direction; visual independency) were scored on a 5-point Likert scale based on video observations of each player and each game. Disagreement between raters was resolved by agreement. Differences in scores for the 3 exergames were analyzed with a multivariate one-way ANOVA. The Mole received the highest sum score and the best score on each of the 5 movement characteristics (all p values <0.0005). LightRace scored the lowest of the 3 exergames on weight shift and variation in movement direction (both p values <0.0005), while DanceDanceRevolution scored lowest on step length variation and visual independency (p < 0.03 and p < 0.0005, respectively), and lower than The Mole on speed variation (p < 0.05). The physical space players used when exergaming and the on-screen representation of the player, affected movement quality positively as indexed by multiple weight shifts and variation in stepping size, direction, and speed. Furthermore, players' movements improved when playing speed-affected game progression and when the game narrative was related to a natural context. Comparing differences in game elements with associated differences in game movement requirements provides valuable insights about how to design for movement quality in exergames. This provided important lessons for the design of exergames for fall-preventive exercise in senior citizens and illustrates the value of including analyses of movement characteristics when designing such exergames. © 2014 S. Karger AG, Basel.

The science of badminton: game characteristics, anthropometry, physiology, visual fitness and biomechanics.

PubMed

Phomsoupha, Michael; Laffaye, Guillaume

2015-04-01

Badminton is a racket sport for two or four people, with a temporal structure characterized by actions of short duration and high intensity. This sport has five events: men's and women's singles, men's and women's doubles, and mixed doubles, each requiring specific preparation in terms of technique, control and physical fitness. Badminton is one of the most popular sports in the world, with 200 million adherents. The decision to include badminton in the 1992 Olympics Game increased participation in the game. This review focuses on the game characteristics, anthropometry, physiology, visual attributes and biomechanics of badminton. Players are generally tall and lean, with an ectomesomorphic body type suited to the high physiological demands of a match. Indeed, a typical match characteristic is a rally time of 7 s and a resting time of 15 s, with an effective playing time of 31%. This sport is highly demanding, with an average heart rate (HR) of over 90% of the player's maximal HR. The intermittent actions during a game are demanding on both the aerobic and anaerobic systems: 60-70% on the aerobic system and approximately 30% on the anaerobic system, with greater demand on the alactic metabolism with respect to the lactic anaerobic metabolism. The shuttlecock has an atypical trajectory, and the players perform specific movements such as lunging and jumping, and powerful strokes using a specific pattern of movement. Lastly, badminton players are visually fit, picking up accurate visual information in a short time. Knowledge of badminton can help to improve coaching and badminton skills.

Physiological and skill demands of 'on-side' and 'off-side' games.

PubMed

Gabbett, Tim J; Jenkins, David G; Abernethy, Bruce

2010-11-01

This study investigated the physiological and skill demands of 'on-side' and 'off-side' games in elite rugby league players. Sixteen male rugby league players participated in 'on-side' and 'off-side' games. Both small-sided games were played in a 40- × 40-m playing area. The 'off-side' game permitted players to have 3 'plays' while in possession of the ball. Players were permitted to pass backward or forward (to an 'off-side' player). The 'on-side' game also permitted players to have 3 'plays' while in possession of the ball. However, players were only permitted to pass backward to players in an 'on-side' position. Heart rate and movement patterns (via global positioning system) were recorded continuously throughout both games. Data were collected on the distance covered, number of high-acceleration and velocity efforts, and recovery between efforts. Video footage was also taken to track the performance of the players. Post hoc inspection of the footage was undertaken to count the number of possessions and the number and quality of disposals. In comparison to 'on-side' games, 'off-side' games had a greater number of involvements ("touches"), passes, and effective passes. However, the cognitive demands of 'on-side' games were greater than 'off-side' games. 'Off-side' games resulted in a greater total distance covered, greater distance covered in mild and moderate accelerations, and greater distance covered in low, moderate, and high-velocity efforts. There were also a greater number of short duration recovery periods between efforts in 'off-side' games. The results of this study demonstrate that 'off-side' games provide greater physiological and skill demands than 'on-side' games. 'Off-side' games may provide a practical alternative to 'on-side' games for the development of skill and fitness in elite rugby league players.

Effects of special exercise programs on functional movement screen scores and injury prevention in preprofessional young football players.

PubMed

Dinc, Engin; Kilinc, Bekir Eray; Bulat, Muge; Erten, Yunus Turgay; Bayraktar, Bülent

2017-10-01

To increase movement capacity and to reduce injury risk in young soccer players by implementing a special functional exercise program based on functional movement screen (FMS) and correctives. 67 young male athletes 14-19 years of age from a Super League Football Club Academy participated in the study. Functional movement patterns were evaluated with FMS assessment protocol. Deep squat, hurdle step, inline lunge, shoulder mobility, active straight leg raise, trunk stability push-up, and rotatory stability were examined in FMS. Considering the FMS scores the number of intervention and control groups were defined as 24 and 43, respectively. Intervention program was composed of 1 hr twice a week sessions in total of 12 weeks with 4 weeks of mobility, 4 weeks of stability, and 4 weeks of integration exercises. At the end of 12-week intervention and control groups were re-evaluated with FMS protocol. Contact and noncontact sports injuries recorded during one season. In intervention group there was statistically significant difference in increase in total FMS scores ( P <0.01), deep squat ( P ≤0.001), hurdle step ( P <0.05), inline lunge ( P <0.01), and trunk stability push-up ( P <0.01). In control group total FMS, deep squat, and trunk stability push-up scores increased with a statistical difference ( P <0.01, P <0.05, P ≤0.01, respectively). The incidence of noncontact injury in control group was higher than intervention group ( P <0.05). Periodic movement screening and proper corrections with functional training is valuable in order to create better movement capacity to build better physical performance and more effective injury prevention.

Physiological Profile and Activity Pattern of Minor Gaelic Football Players.

PubMed

Cullen, Bryan D; Roantree, Mark T; McCarren, Andrew L; Kelly, David T; OʼConnor, Paul L; Hughes, Sarah M; Daly, Pat G; Moyna, Niall M

2017-07-01

Cullen, BD, Roantree, M, McCarren, A, Kelly, DT, O'Connor, PL, Hughes, SM, Daly, PG, and Moyna1, NM. Physiological profile and activity pattern of minor Gaelic football players. J Strength Cond Res 31(7): 1811-1820, 2017-The purpose of this study was to evaluate the physiological profile and activity pattern in club- and county-level under-18 (U-18) Gaelic football players relative to playing position. Participants (n = 85) were analyzed during 17 official 15-a-side matches using global positioning system technology (SPI Pro X II; GPSports Systems, Canberra, Australia) and heart rate (HR) telemetry. During the second part of this study, 63 participants underwent an incremental treadmill test to assess their maximal oxygen uptake (V[Combining Dot Above]o2max) and peak HR (HRmax). Players covered a mean distance of 5,774 ± 737 m during a full 60-minute match. The mean %HRmax and %V[Combining Dot Above]O2max observed during the match play were 81.6 ± 4.3% and 70.1 ± 7.75%, respectively. The playing level had no effect on the distance covered, player movement patterns, or %HRmax observed during match play. Midfield players covered significantly greater distance than defenders (p = 0.033). Playing position had no effect on %HRmax or the frequency of sprinting or high-intensity running during match play. The frequency of jogging, cruise running, striding (p = 0.000), and walking (p = 0.003) was greater in the midfield position than in the forward position. Time had a significant effect (F(1,39) = 33.512, p-value = 0.000, and (Equation is included in full-text article.)= 0.462) on distance covered and %HRmax, both of which showed a reduction between playing periods. Gaelic football is predominantly characterized by low-to-moderate intensity activity interspersed with periods of high-intensity running. The information provided may be used as a framework for coaches in the design and prescription of training strategies. Positional specific training may be warranted given the comparatively greater demands observed in the midfield playing position. Replicating the demands of match play in training may reduce the decline in distance covered and %HRmax observed during the second half of match play.

Pelvic Rotation and Lower Extremity Motion with Two Different Front Foot Directions in the Tennis Backhand Groundstroke

PubMed Central

Iwamoto, Sayumi; Fukubayashi, Toru; Hume, Patria

2013-01-01

When a tennis player steps forward to hit a backhand groundstroke in closed stance, modifying the direction of the front foot relative to the net may reduce the risk of ankle injury and increase performance. This study evaluated the relationship between pelvic rotation and lower extremity movement during the backhand groundstroke when players stepped with toes parallel to the net (Level) or with toes pointed towards the net (Net). High school competitive tennis players (eleven males and seven females, 16.8 ± 0.8 years, all right- handed) performed tennis court tests comprising five maximum speed directional runs to the court intersection line to hit an imaginary ball with forehand or backhand swings. The final backhand groundstroke for each player at the backcourt baseline was analyzed. Pelvic rotation and lower extremity motion were quantified using 3D video analysis from frontal and sagittal plane camera views reconstructed to 3D using DLT methods. Plantar flexion of ankle and supination of the front foot were displayed for both Net and Level groups during the late phase of the front foot step. The timings of the peak pelvis rotational velocity and peak pelvis rotational acceleration showed different pattern for Net and Level groups. The peak timing of the pelvis rotational velocity of the Level group occurred during the late phase of the step, suggesting an increase in the risk of inversion ankle sprain and a decrease in stroke power compared to the Net group. Key Points Regarding the movement of the forefoot, the Net group and the Level group showed a pattern of supination-pronation-supination during the front stepping foot contact phase (FSFCP). However, the Level group showed only supination of various degrees during FSFCP. For the Net group, the maximum angular velocity of pelvis occurred in the early phase of FSFCP before impact; however, for the Level group, the maximum angular velocity of pelvis occurred in the latter phase of FSFCP after impact. The Level group players showed a potentially higher risk of inversion ankle sprain during the latter stage of FSFCP as pelvic rotation reached maximum angular velocity. The Net group may have a more effective kinetic chain during backhand groundstrokes, which ultimately enhances performance. PMID:24149814

Distinct eye movement patterns enhance dynamic visual acuity

PubMed Central

Palidis, Dimitrios J.; Wyder-Hodge, Pearson A.; Fooken, Jolande; Spering, Miriam

2017-01-01

Dynamic visual acuity (DVA) is the ability to resolve fine spatial detail in dynamic objects during head fixation, or in static objects during head or body rotation. This ability is important for many activities such as ball sports, and a close relation has been shown between DVA and sports expertise. DVA tasks involve eye movements, yet, it is unclear which aspects of eye movements contribute to successful performance. Here we examined the relation between DVA and the kinematics of smooth pursuit and saccadic eye movements in a cohort of 23 varsity baseball players. In a computerized dynamic-object DVA test, observers reported the location of the gap in a small Landolt-C ring moving at various speeds while eye movements were recorded. Smooth pursuit kinematics—eye latency, acceleration, velocity gain, position error—and the direction and amplitude of saccadic eye movements were linked to perceptual performance. Results reveal that distinct eye movement patterns—minimizing eye position error, tracking smoothly, and inhibiting reverse saccades—were related to dynamic visual acuity. The close link between eye movement quality and DVA performance has important implications for the development of perceptual training programs to improve DVA. PMID:28187157

The coupling between gaze behavior and opponent kinematics during anticipation of badminton shots.

PubMed

Alder, David; Ford, Paul R; Causer, Joe; Williams, A Mark

2014-10-01

We examined links between the kinematics of an opponent's actions and the visual search behaviors of badminton players responding to those actions. A kinematic analysis of international standard badminton players (n = 4) was undertaken as they completed a range of serves. Video of these players serving was used to create a life-size temporal occlusion test to measure anticipation responses. Expert (n = 8) and novice (n = 8) badminton players anticipated serve location while wearing an eye movement registration system. During the execution phase of the opponent's movement, the kinematic analysis showed between-shot differences in distance traveled and peak acceleration at the shoulder, elbow, wrist and racket. Experts were more accurate at responding to the serves compared to novice players. Expert players fixated on the kinematic locations that were most discriminating between serve types more frequently and for a longer duration compared to novice players. Moreover, players were generally more accurate at responding to serves when they fixated vision upon the discriminating arm and racket kinematics. Findings extend previous literature by providing empirical evidence that expert athletes' visual search behaviors and anticipatory responses are inextricably linked to the opponent action being observed. Copyright © 2014 Elsevier B.V. All rights reserved.

Performance enhancement among adolescent players after 10 weeks of pitching training with appropriate baseball weights.

PubMed

Yang, Wen-Wen; Liu, Ya-Chen; Lu, Lee-Chang; Chang, Hsiao-Yun; Chou, Paul Pei-Hsi; Liu, Chiang

2013-12-01

Compared with regulation-weight baseballs, lightweight baseballs generate lower torque on the shoulder and elbow joints without altering the pitching movement and timing. This study investigates the throwing accuracy, throwing velocity, arm swing velocity, and maximum shoulder external rotation (MSER) of adolescent players after 10 weeks of pitching training with appropriate lightweight baseballs. We assigned 24 adolescent players to a lightweight baseball group (group L) and a regulation-weight baseball group (group R) based on their pretraining throwing velocity. Both groups received pitching training 3 times per week for 10 weeks with 4.4- and 5-oz baseballs. The players' throwing accuracy, throwing velocity, arm swing velocity, and MSER were measured from 10 maximum efforts throws using a regulation-weight baseball before and after undergoing the pitching training. The results showed that the players in group L significantly increased their throwing velocity and arm swing velocity (p < 0.05) after 10 weeks of pitching training with the 4.4-oz baseball, whereas group R did not (p > 0.05). Furthermore, the percentage change in the throwing velocity and arm swing velocity of group L was significantly superior to that of group R (p < 0.05). Thus, we concluded that the 10 weeks of pitching training with an appropriate lightweight baseball substantially enhanced the arm swing velocity and throwing velocity of the adolescent baseball players. These findings suggest that using a lightweight baseball, which can reduce the risk of injury without altering pitching patterns, has positive training effects on players in the rapid physical growth and technique development stage.

Bilateral and Unilateral Asymmetries of Isokinetic Strength and Flexibility in Male Young Professional Soccer Players

PubMed Central

Daneshjoo, Abdolhamid; Rahnama, Nader; Mokhtar, Abdul Halim; Yusof, Ashril

2013-01-01

This study investigated bilateral and unilateral asymmetries of strength and flexibility in male young professional soccer players. Thirty-six soccer players (age: 18.9 ± 1.4 years) participated in this study. A Biodex Isokinetic Dynamometer was used to assess the hamstring and quadriceps strength at selected speeds of 60°/s, 180°/s and 300°/s. Hip joint flexibility was measured using a goniometer. No difference was observed in conventional strength ratio, dynamic control ratio and fast/slow speed ratio between the dominant and non-dominant legs (p>0.05). All but one of the players (97.2%) had musculoskeletal abnormality (bilateral imbalance > 10%) in one or more specific muscle groups. The dominant leg had greater hip joint flexibility compared with the non-dominant leg (108.8 ± 10.7° versus 104.6 ± 9.8°, respectively). The findings support the hypothesis that physical performance and movement pattern experienced during soccer playing may negatively change the balance of strength in both legs (bilateral strength balance), but not on the same leg of the young male professional soccer players. The results can be helpful for trainers and coaches to decide whether the players need to improve their balance and strength which in turn may prevent injury. It is suggested that in professional soccer training, quadriceps and hamstrings muscle strength, as well as hip joint flexibility should not be overlooked. PMID:23717354

Specific Shoulder Pathoanatomy in Semiprofessional Water Polo Players

PubMed Central

Klein, Maria; Tarantino, Ignazio; Warschkow, René; Berger, Claus Joachim; Zdravkovic, Vilijam; Jost, Bernhard; Badulescu, Michael

2014-01-01

Background: Shoulders of throwing and swimming athletes are highly stressed joints that often show structural abnormalities on magnetic resonance imaging (MRI). However, while water polo players exhibit a combination of throwing and swimming movements, a specific pattern of pathological findings has not been described. Purpose: To assess specific MRI abnormalities in shoulders of elite water polo players and to compare these findings with a healthy control group. Study Design: Cross-sectional study; Level of evidence, 3. Methods: After performing a power analysis, volunteers were recruited for this study. Both shoulders of 28 semiprofessional water polo players and 15 healthy volunteers were assessed clinically (based on the Constant score) and had bilateral shoulder MRIs. The shoulders were clustered into 3 groups: 28 throwing and 28 nonthrowing shoulders of water polo athletes and 30 shoulders of healthy control subjects. Results: Twenty-eight male water polo players with an average age of 24 years and 15 healthy subjects (30 shoulders) with an average age of 31 years were examined. Compared with controls, significantly more MRI abnormalities in the water polo players' throwing shoulders could be found in the subscapularis, infraspinatus, and posterior labrum (P = .001, P = .024, and P = .041, respectively). Other structures showed no statistical differences between the 3 groups, including the supraspinatus tendon, which had abnormalities in 36% of throwing versus 32% of nonthrowing shoulders and 33% of control shoulders. All throwing shoulders showed abnormal findings in the MRI, but only 8 (29%) were symptomatic. Conclusion: The shoulders of semiprofessional water polo players demonstrated abnormalities in subscapularis and infraspinatus tendons that were not typical abnormalities for swimmers or throwing athletes. Clinical Relevance: The throwing shoulders of water polo players have specific MRI changes. Clinical symptoms do not correlate with the MRI findings. PMID:26535326

Effect of core stability training on throwing velocity in female handball players.

PubMed

Saeterbakken, Atle H; van den Tillaar, Roland; Seiler, Stephen

2011-03-01

The purpose was to study the effect of a sling exercise training (SET)-based core stability program on maximal throwing velocity among female handball players. Twenty-four female high-school handball players (16.6 ± 0.3 years, 63 ± 6 kg, and 169 ± 7 cm) participated and were initially divided into a SET training group (n = 14) and a control group (CON, n = 10). Both groups performed their regular handball training for 6 weeks. In addition, twice a week, the SET group performed a progressive core stability-training program consisting of 6 unstable closed kinetic chain exercises. Maximal throwing velocity was measured before and after the training period using photocells. Maximal throwing velocity significantly increased 4.9% from 17.9 ± 0.5 to 18.8 ± 0.4 m·s in the SET group after the training period (p < 0.01), but was unchanged in the control group (17.1 ± 0.4 vs. 16.9 ± 0.4 m·s). These results suggest that core stability training using unstable, closed kinetic chain movements can significantly improve maximal throwing velocity. A stronger and more stable lumbopelvic-hip complex may contribute to higher rotational velocity in multisegmental movements. Strength coaches can incorporate exercises exposing the joints for destabilization force during training in closed kinetic chain exercises. This may encourage an effective neuromuscular pattern and increase force production and can improve a highly specific performance task such as throwing.

Kinetic and Kinematic Analysis for Assessing the Differences in Countermovement Jump Performance in Rugby Players.

PubMed

Floría, Pablo; Gómez-Landero, Luis A; Suárez-Arrones, Luis; Harrison, Andrew J

2016-09-01

Floría, P, Gómez-Landero, LA, Suárez-Arrones, L, and Harrison, AJ. Kinetic and kinematic analysis for assessing the differences in countermovement jump performance in rugby players. J Strength Cond Res 30(9): 2533-2539, 2016-The aim of this study was to ascertain the differences in kinetic and kinematic profiles between better and poorer performers of the vertical jump within a homogeneous group of trained adults. Fifty rugby players were divided into low scoring (LOW) and high scoring (HIGH) groups based on their performance in the vertical jump. The force, velocity, displacement, and rate of force development (RFD)-time curves were analyzed to determine the differences between groups. The analysis of the data showed differences in all the patterns of the ensemble mean curves of the HIGH and LOW groups. During the eccentric phase, the differences in the HIGH group with respect to the LOW group were lower crouch position, higher downward velocity, and higher force and RFD during the braking of the downward movement. During the concentric phase, the HIGH group achieved higher upward velocity, higher force at the end of phase, and a higher position at takeoff. The higher jump performances seem to be related to a more effective stretch-shortening cycle function that is characterized by a deeper and faster countermovement with higher eccentric forces being applied to decelerate the downward movement leading to enhanced force generation during the concentric phase.

Improving the 'how' and 'what' decisions of elite table tennis players.

PubMed

Raab, Markus; Masters, Rich S W; Maxwell, Jonathan P

2005-06-01

Training methods in sport usually focus on improving either technical or tactical aspects of performance, ignoring the fact that successful performance requires the athlete to simultaneously decide what movement to perform and how it should be executed. Young elite table tennis players were trained, in a first phase, to improve their forehand and backhand movements and, in a second phase, to make a tactical switch between forehand and backhand movements. Half of the players took part in behavioral training focusing on how to perform the required movements, whereas half received additional video feedback about their technical and tactical performance (decision training). The results indicate that improvements of how decisions (techniques) and what decisions (tactics) can occur as a consequence of combining technical and tactical training. These results were stable in delayed Post-test analyses of competitive matches. It was concluded that a combination of both technical and tactical training is beneficial to elite table tennis performers, particularly during early seasonal training programs.

Wearable nanosensor system for monitoring mild traumatic brain injuries in football players

NASA Astrophysics Data System (ADS)

Ramasamy, Mouli; Varadan, Vijay K.

2016-04-01

Football players are more to violent impacts and injuries more than any athlete in any other sport. Concussion or mild traumatic brain injuries were one of the lesser known sports injuries until the last decade. With the advent of modern technologies in medical and engineering disciplines, people are now more aware of concussion detection and prevention. These concussions are often overlooked by football players themselves. The cumulative effect of these mild traumatic brain injuries can cause long-term residual brain dysfunctions. The principle of concussion is based the movement of the brain in the neurocranium and viscerocranium. The brain is encapsulated by the cerebrospinal fluid which acts as a protective layer for the brain. This fluid can protect the brain against minor movements, however, any rapid movements of the brain may mitigate the protective capability of the cerebrospinal fluid. In this paper, we propose a wireless health monitoring helmet that addresses the concerns of the current monitoring methods - it is non-invasive for a football player as helmet is not an additional gear, it is efficient in performance as it is equipped with EEG nanosensors and 3D accelerometer, it does not restrict the movement of the user as it wirelessly communicates to the remote monitoring station, requirement of individual monitoring stations are not required for each player as the ZigBee protocol can couple multiple transmitters with one receiver. A helmet was developed and validated according to the above mentioned parameters.

Wireless nanosensors for monitoring concussion of football players

NASA Astrophysics Data System (ADS)

Ramasamy, Mouli; Harbaugh, Robert E.; Varadan, Vijay K.

2015-04-01

Football players are more to violent impacts and injuries more than any athlete in any other sport. Concussion or mild traumatic brain injuries were one of the lesser known sports injuries until the last decade. With the advent of modern technologies in medical and engineering disciplines, people are now more aware of concussion detection and prevention. These concussions are often overlooked by football players themselves. The cumulative effect of these mild traumatic brain injuries can cause long-term residual brain dysfunctions. The principle of concussion is based the movement of the brain in the neurocranium and viscerocranium. The brain is encapsulated by the cerebrospinal fluid which acts as a protective layer for the brain. This fluid can protect the brain against minor movements, however, any rapid movements of the brain may mitigate the protective capability of the cerebrospinal fluid. In this paper, we propose a wireless health monitoring helmet that addresses the concerns of the current monitoring methods - it is non-invasive for a football player as helmet is not an additional gear, it is efficient in performance as it is equipped with EEG nanosensors and 3D accelerometer, it does not restrict the movement of the user as it wirelessly communicates to the remote monitoring station, requirement of individual monitoring stations are not required for each player as the ZigBee protocol can couple multiple transmitters with one receiver. A helmet was developed and validated according to the above mentioned parameters.

Initial Movement and Continuity in Vibrato among High School and University String Players

ERIC Educational Resources Information Center

Geringer, John M.; Allen, Michael L.; MacLeod, Rebecca B.

2005-01-01

The purpose of the present study was to investigate aspects of vibrato performance among high school and university string players. The main questions were to determine whether students consistently initiate vibrato in an upward or downward direction and whether players vibrate continuously when performing slurs. Forty high school and university…

Athlete's heart patterns in elite rugby players: effects of training specificities.

PubMed

Chevalier, Laurent; Kervio, Gaëlle; Corneloup, Luc; Vincent, Marie-Pierre; Baudot, Christophe; Rebeyrol, Jean-Louis; Merle, Francis; Gencel, Laurent; Carré, François

2013-02-01

Athlete's heart patterns have been widely described. However, to our knowledge, few studies have focused on professional rugby players, who train differently according to their field position. To describe electrocardiographic and echocardiographic patterns observed in elite rugby players according to their field position. One hundred and thirty-five professional rugby players at the end of the competitive season were included. According to a modified Pelliccia's classification, 68.1% of electrocardiograms were normal or had minor abnormalities, 27.2% were mildly abnormal and 3.7% were distinctly abnormal. Heart rate was higher in scrum first-row players (P<0.05). Absolute and indexed left ventricular end-diastolic internal diameters (LVIDd; absolute value 59.3±4.7 mm) exceeded 65 mm and 32 mm/m2 in 13% and 1.5% of players, respectively. Indexed LVIDd values were higher in back players (P<0.001). Left ventricular interventricular septum and posterior wall thicknesses (absolute values 9.4±1.7 mm and 9.2±1.6 mm, respectively) exceeded 13 mm in 3.7% of players. Concentric cardiac hypertrophy was noted in 3.7% of players. Except for one Wolff-Parkinson-White pattern, players with significant ECG or echocardiographic abnormalities showed no cardiovascular event or disease during follow-up. Thus, elite rugby players present similar heart patterns to elite athletes in other sports. Major electrocardiographic and echocardiographic abnormalities are quite rare. Eccentric cardiac remodelling is more frequent in back players. Copyright © 2013. Published by Elsevier Masson SAS.

Assessing the Effectiveness of the Functional Movement Screen in Predicting Noncontact Injury Rates in Soccer Players.

PubMed

Smith, Paul D; Hanlon, Michael P

2017-12-01

Smith, PD, and Hanlon, D. Assessing the effectiveness of the functional movement screen in predicting noncontact injury rates in soccer players. J Strength Cond Res 31(12): 3327-3332, 2017-This study assessed if the Functional Movement Screen (FMS) can accurately predict noncontact injury in adult soccer players when normalizing noncontact injury occurrence against match exposure levels. Senior male players (n = 89) from 5 League of Ireland semiprofessional clubs participated in the study (mean age = 23.2 ± 4.4 years; mean height = 179.5 ± 6.6 cm; mean body mass = 77.5 ± 7.8 kg). Participants performed the FMS during preseason, and their injury occurrence rates and match minutes were tracked throughout 1 season. In total, 66 noncontact injuries were recorded. No significant difference was found in FMS composite scores between players receiving noncontact injuries and players not suffering a noncontact injury (p = 0.96). There was no significant difference in exposure-normalized noncontact injury incidence between those scoring 14 or below and those scoring above 14 on the FMS (0.36 vs. 0.29 non-contact injuries per player per 1,000 match minutes). Players scoring 14 or below on the FMS had an odds ratio of 0.63 (p = 0.45; 95% CI = 0.19-2.07) of receiving a noncontact injury. Despite previous research showing links between low FMS composite scores and subsequent injury, these results suggest that the FMS cannot accurately predict a male soccer player's likelihood of receiving a noncontact injury and that a lower FMS composite score does not significantly increase their noncontact injury incidence rate per 1,000 match minutes. Caution should therefore be used when using the FMS as a predictor of noncontact injury, and pain prevalence during the FMS, previous injuries, and training/match exposure levels should also be taken into account.

Comparison of the Kinematic Patterns of Kick Between Brazilian and Japanese Young Soccer Players

PubMed Central

Pereira Santiago, Paulo Roberto; Palucci Vieira, Luiz Henrique; Barbieri, Fabio Augusto; Moura, Felipe Arruda; Exel Santana, Juliana; de Andrade, Vitor Luiz; de Souza Bedo, Bruno Luiz; Cunha, Sergio Augusto

2016-01-01

Background Kicking performance is the most studied technical action in soccer and lower limbs kinematics is closely related to success in kicking, mainly because they are essential in imparting high velocity to the ball. Previous studies demonstrated that soccer leagues in different countries exhibit different physical demands and technical requirements during the matches. However, evidencewhether nationality has any influence in the kinematics of soccer-related skills has not yet been reported. The nationality of the players is an aspect that might be also relevant to the performance in kicking. Objectives The aim of this study was to compare the lower limbs kinematic patterns during kicking, between Brazilian and Japanese young top soccer players. Patients and Methods Seven Brazilian (GA) and seven Japanese (GB) U-17 players performed 15 side-foot kicks each, with a distance of 20 m away from the goal, aiming a target of 1 × 1 m in upper corner, constrained by a defensive wall (1.8 × 2 m). Four digital video cameras (120 Hz) recorded the performance for further 3D reconstruction of thigh, shank and foot segments of both kicking and support limbs. The selected kicking cycle was characterized by the toe-off of the kicking limb to the end of the kicking foot when it came in contact with the ball. Stereographical projection of each segment was applied to obtain the representative curves of kicking as function of time for each participant in each trial. Cluster analysis was performed to identify the mean GA and GB curves for each segment. Silhouette coefficient (SC) was calculated, in order to determine the degree of separation between the two groups’ curves. Results Comparison between the median confidence intervals of the SC showed no differences between groups as regards lower limb patterns of movements. Task accuracy was determined by the relative frequency that the ball reached the target for all attempts and no differences were found (GA: 10.48 ± 14.33%; GB: 9.52 ± 6.51%; P = 0.88). Conclusions We conclude that lower limb kinematic patterns, in support and ball contact phases, are similar in young Brazilian and Japanese soccer players during free kicks when adopting the side-foot kick style. PMID:27625761

Upper-body kinematics in team-handball throw, tennis serve, and volleyball spike.

PubMed

Wagner, H; Pfusterschmied, J; Tilp, M; Landlinger, J; von Duvillard, S P; Müller, E

2014-04-01

Overarm movements are essential skills in many different sport games; however, the adaptations to different sports are not well understood. The aim of the study was to analyze upper-body kinematics in the team-handball throw, tennis serve, and volleyball spike, and to calculate differences in the proximal-to-distal sequencing and joint movements. Three-dimensional kinematic data were analyzed via the Vicon motion capturing system. The subjects (elite players) were instructed to perform a team-handball jump throw, tennis serve, and volleyball spike with a maximal ball velocity and to hit a specific target. Significant differences (P < 0.05) between the three overarm movements were found in 17 of 24 variables. The order of the proximal-to-distal sequencing was equal in the three analyzed overarm movements. Equal order of the proximal-to-distal sequencing and similar angles in the acceleration phase suggest there is a general motor pattern in overarm movements. However, overarm movements appear to be modifiable in situations such as for throwing or hitting a ball with or without a racket, and due to differences at takeoff (with one or two legs). © 2012 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Fluid and Electrolyte Needs for Training, Competition, and Recovery

DTIC Science & Technology

2011-01-01

begin both training and competition in a state of fluid deficit. Analysis of samples collected from elite football ( soccer ) players before training...surprisingly, samples collected from players before a competitive game revealed that 8 of the 20 outfield players had a urine osmolality in excess of...2007) reported that basketball players attempted fewer shots and were less able to make shots linked with movement (e.g. lay-up) when dehydration had

Effectiveness of a tailored neck training program on neck strength, movement, and fatigue in under-19 male rugby players: a randomized controlled pilot study.

PubMed

Barrett, Matthew D; McLoughlin, Terence F; Gallagher, Kieran R; Gatherer, Don; Parratt, Michael Tr; Perera, Jonathan R; Briggs, Tim Wr

2015-01-01

To investigate the effect of a tailored neck muscle conditioning program on neck muscle strength, neck muscle fatigue, and range of neck movement in 16-18-year-old male rugby players. Thirty-four male rugby players were divided into forward and back playing positions and randomized within these groups. Seventeen players were randomly assigned to each group. The test group was given a tailored 6-week exercise regime based on their baseline measurements to be performed three times a week in addition to their normal training and playing. The control group trained and played as normal. The outcome measures used were cervical spine range of movement, neck strength, and neck muscle fatigability. There were no clinically relevant statistically significant differences between the two groups. Trends identified between the two groups suggest that a tailored neck exercise program increases neck strength, particularly neck extension, and increases resistance to fatigue, as well as influencing right- and left-sided neck muscle balance. A reduction in range of movement was also demonstrated in the test group. There was a great deal of variability in range of movement and strength within this age group. No previously undiagnosed neck conditions were detected, and there were no adverse events reported. This study has shown that neck strength, range of movement, and susceptibility of the neck muscles to fatigue can be influenced using a focused neck training regime. It forms an important basis for a larger, multicenter study to ensure the neck is given due attention in rugby training and receives the same focus of conditioning as other parts of the body.

Perceiving patterns of play in dynamic sport tasks: investigating the essential information underlying skilled performance.

PubMed

Willams, A Mark; Hodges, Nicola J; North, Jamie S; Barton, Gabor

2006-01-01

The perceptual-cognitive information used to support pattern-recognition skill in soccer was examined. In experiment 1, skilled players were quicker and more accurate than less-skilled players at recognising familiar and unfamiliar soccer action sequences presented on film. In experiment 2, these action sequences were converted into point-light displays, with superficial display features removed and the positions of players and the relational information between them made more salient. Skilled players were more accurate than less-skilled players in recognising sequences presented in point-light form, implying that each pattern of play can be defined by the unique relations between players. In experiment 3, various offensive and defensive players were occluded for the duration of each trial in an attempt to identify the most important sources of information underpinning successful performance. A decrease in response accuracy was observed under occluded compared with non-occluded conditions and the expertise effect was no longer observed. The relational information between certain key players, team-mates and their defensive counterparts may provide the essential information for effective pattern-recognition skill in soccer. Structural feature analysis, temporal phase relations, and knowledge-based information are effectively integrated to facilitate pattern recognition in dynamic sport tasks.

Learning to play the violin: motor control by freezing, not freeing degrees of freedom.

PubMed

Konczak, Jürgen; Vander Velden, Heidi; Jaeger, Lukas

2009-05-01

Playing a violin requires precise patterns of limb coordination that are acquired over years of practice. In the present study, the authors investigated how motion at proximal arm joints influenced the precision of bow movements in novice learners and experts. The authors evaluated the performances of 11 children (4-12 years old), 3 beginning-to-advanced level adult players, and 2 adult concert violinists, using a musical work that all had mastered as their first violin piece. The authors found that learning to play the violin was not associated with a release or freeing of joint degrees of freedom. Instead, learning was characterized by an experience-dependent suppression of sagittal shoulder motion, as documented by an observed reduction in joint angular amplitude. This reduction in the amplitude of shoulder flexion-extension correlated highly with a decrease of bow-movement variability. The remaining mechanical degrees of freedom at the elbow and shoulder showed patterns of neither suppression nor freeing. Only violinists with more than 700 practice hr achieved sagittal shoulder range of motion comparable to experts. The findings imply that restricting joint amplitude at selected joint degrees of freedom, while leaving other degrees of freedom unconstrained, constitutes an appropriate strategy for learning complex, high-precision motor patterns in children and adults. The findings also highlight that mastering even seemingly simple bowing movements constitutes a prolonged learning process.

The key to success in elite athletes? Explicit and implicit motor learning in youth elite and non-elite soccer players.

PubMed

Verburgh, L; Scherder, E J A; van Lange, P A M; Oosterlaan, J

2016-09-01

In sports, fast and accurate execution of movements is required. It has been shown that implicitly learned movements might be less vulnerable than explicitly learned movements to stressful and fast changing circumstances that exist at the elite sports level. The present study provides insight in explicit and implicit motor learning in youth soccer players with different expertise levels. Twenty-seven youth elite soccer players and 25 non-elite soccer players (aged 10-12) performed a serial reaction time task (SRTT). In the SRTT, one of the sequences must be learned explicitly, the other was implicitly learned. No main effect of group was found for implicit and explicit learning on mean reaction time (MRT) and accuracy. However, for MRT, an interaction was found between learning condition, learning phase and group. Analyses showed no group effects for the explicit learning condition, but youth elite soccer players showed better learning in the implicit learning condition. In particular, during implicit motor learning youth elite soccer showed faster MRTs in the early learning phase and earlier reached asymptote performance in terms of MRT. Present findings may be important for sports because children with superior implicit learning abilities in early learning phases may be able to learn more (durable) motor skills in a shorter time period as compared to other children.

Strength and Power Correlates of Throwing Velocity on Subelite Male Cricket Players.

PubMed

Freeston, Jonathan L; Carter, Thomas; Whitaker, Gary; Nicholls, Owen; Rooney, Kieron B

2016-06-01

Throwing velocity is an important aspect of fielding in cricket to affect run-outs and reduce the opponent's run-scoring opportunities. Although a relationship between strength and/or power and throwing velocity has been well established in baseball, water polo, and European handball, it has not been adequately explored in cricket. Consequently, this study aimed to determine the relationship between measures of strength and/or power and throwing velocity in cricket players. Seventeen male cricket players (mean ± SD; age, 21.1 ± 1.6 years; height, 1.79 ± 0.06 m; weight, 79.8 ± 6.4 kg) from an elite athlete program were tested for maximal throwing velocity from the stretch position and after a 3-meter shuffle. They were also assessed for strength and power using a range of different measures. Throwing velocity from the stretch position (30.5 ± 2.4 m·s) was significantly related to dominant leg lateral-to-medial jump (LMJ) distance (r = 0.71; p < 0.01), dominant shoulder internal rotation (IR) strength (r = 0.55; p ≤ 0.05), and dominant (r = 0.73; p < 0.01) and nondominant (r = 0.54; p ≤ 0.05) medicine ball rotation (MB Rot) throw velocity and medicine ball chest pass (MB CP) distance (r = 0.67; p < 0.01). A nonsignificant trend was observed for vertical jump (VJ) height (p = 0.06), whereas no significant relationships were observed for nondominant LMJ distance (p = 0.97), nondominant shoulder IR strength (p = 0.80), 1 repetition maximum (RM) squat strength (p = 0.57), 1RM bench press strength (p = 0.90), height (p = 0.33), or weight (p = 0.29). Multiple regression analysis revealed that dominant MB Rot and MB CP explained 66% of the variance. The results were similar for velocity after a shuffle step (31.8 ± 2.1 m·s); however, VJ height reached statistical significance (r = 0.51; p ≤ 0.05). The multiple regression was also similar with MB Rot and MB CP explaining 70% of the variance. The cricketers in this study threw with greater velocity than elite junior and subelite senior cricketers but with lower velocities than elite senior cricketers and collegiate level and professional baseball players. This is the first study to demonstrate a link between strength and/or power and throwing velocity in cricket players and highlight the importance of power development as it relates to throwing velocity. Exercises that more closely simulated the speed (body weight jumps and medicine ball throws) or movement pattern (shoulder IR) of overhead throwing were greater predictors of throwing velocity. Strength and conditioning staff should assess and develop power to enhance throwing performance in cricket players. Exercises with greater movement and speed specificity to throwing should be used in preference over exercises that are slower and have less movement specificity to the throwing motion. Cricket players should engage in power training to bridge the gap in performance between them and baseball players.

Quantification of Competitive Game Demands of NCAA Division I College Football Players Using Global Positioning Systems.

PubMed

Wellman, Aaron D; Coad, Sam C; Goulet, Grant C; McLellan, Christopher P

2016-01-01

The aim of the present study was to examine the competitive physiological movement demands of National Collegiate Athletic Association (NCAA) Division I college football players using portable global positioning system (GPS) technology during games and to examine positional groups within offensive and defensive teams, to determine if a player's physiological requirements during games are influenced by playing position. Thirty-three NCAA Division I Football Bowl Subdivision football players were monitored using GPS receivers with integrated accelerometers (GPSports) during 12 regular season games throughout the 2014 season. Individual data sets (n = 295) from players were divided into offensive and defensive teams and subsequent position groups. Movement profile characteristics, including total, low-intensity, moderate-intensity, high-intensity, and sprint running distances (m), sprint counts, and acceleration and deceleration efforts, were assessed during games. A one-way ANOVA and post-hoc Bonferroni statistical analysis were used to determine differences in movement profiles between each position group within offensive and defensive teams. For both offensive and defensive teams, significant (p ≤ 0.05) differences exist between positional groups for game physical performance requirements. The results of the present study identified that wide receivers and defensive backs completed significantly (p ≤ 0.05) greater total distance, high-intensity running, sprint distance, and high-intensity acceleration and deceleration efforts than their respective offensive and defensive positional groups. Data from the present study provide novel quantification of position-specific physical demands of college football games and support the use of position-specific training in the preparation of NCAA Division I college football players for competition.

The development of aerobic and skill assessment in soccer.

PubMed

O'Reilly, John; Wong, Stephen H S

2012-12-01

Methods of assessing soccer players' performance have developed significantly in recent times. The fitness profiles and skill levels of a prospective elite soccer player is a valuable resource for coaches in the process of identifying talent. Traditional means to measure aerobic fitness have centred on the 'aerobic capacity' or '&OV0312;O(2max)' test (also known as the maximal oxygen consumption test) but, over time, this has been shown not to be a sensitive measure for specific aspects of soccer in a match situation. Therefore, numerous soccer-specific simulations have been designed to re-create exercise patterns similar to those experienced during a match. Some of these studies have yet to be validated, while others have been shown to result in a similar physiological load to that encountered during regular match play. Further developments have led to specifically designed intermittent sprint tests, which are used as a sensitive tool to accurately measure the fluctuations in players' ability both between and within soccer seasons. Testing procedures have also been developed that incorporate elements of both skill and physical ability. Soccer-specific field tests have been designed, incorporating skill and dynamic movements, and this opens up the possibility of teams testing the aerobic capacity of their elite players using soccer-specific movements. Valid studies assessing soccer-specific skills in an ecologically sound environment have been quite rare until recently. Some test protocols have been deemed largely irrelevant to soccer match play, while others have had limited impact on scientific literature. More recently, skill tests have been developed and shown to be valid and reliable methods of assessing soccer skill performance. Many new skill tests continue to be developed, and some have been shown to be highly reliable, but further study of these relatively novel concepts is required before a more solid recommendation can be made. Overall, while significant work has been completed to date, there is still a need for further focused investigations, which can more closely assess the physiological demands of an elite soccer player, with a particular emphasis on sport-specific exercises during the execution of soccer skills. In this regard, more reliable and specific performance tests can be designed to more efficiently assess soccer players in the future.

Effects of an In-season Plyometric Training Program on Repeated Change of Direction and Sprint Performance in the Junior Soccer Player.

PubMed

Hammami, Mehréz; Negra, Yassine; Aouadi, Ridha; Shephard, Roy J; Chelly, Mohamed Souhaiel

2016-12-01

Hammami, M, Negra, Y, Aouadi, R, Shephard, RJ, and Chelly, MS. Effects of an in-season plyometric training program on repeated change of direction and sprint performance in the junior soccer player. J Strength Cond Res 30(12): 3312-3320, 2016-We aimed to determine the gains in explosive movements of male junior soccer players induced by incorporating an 8-week plyometric training program (PTP) into a standard soccer conditioning regimen 5 months after the beginning of the competitive season. Our hypothesis was that PTP would enhance explosive movements, and thus sprint running, repeated shuttle sprint ability (RSSA), agility and the ability to make repeated changes of direction (RCOD). A group of junior soccer players were randomly divided into 2 groups: an experimental group (E, n = 15, age 15.7 ± 0.2 years) and a control group (C, n = 13, age 15.8 ± 0.2 years). The participants in E and C performed training exercises and matches together, but for an 8-week period in the latter part of the season, the experimental group replaced a part of the normal regimen (the tactical session) by a biweekly course of PTP (hurdle and drop jumps). Two familiarization sessions were held 2 weeks before definitive testing. The ability of the players was assessed by 3 agility tests (a sprint test with 180° turns, a 9-3-6-3-9 m sprint with backward and forward running, and a four 5-m sprint test with turns); 2 repeated sprint tests (RSSA and RCOD); and running times over 5-, 10-, 20-, 30-, and 40-m distances. Participants in E showed gains relative to C in sprint times (p ≤ 0.05 for 5, 10, and 20 m), and 2 of 3 the RCOD parameters (RCOD best, p ≤ 0.001; RCOD total, p ≤ 0.05). However, with the pattern of plyometric training that we adopted, and perhaps because participants were in good initial physical condition, the agility and RSSA test scores remained unchanged. Nevertheless, we conclude that our PTP can be commended to junior soccer players as a means of improving important components of their physical performance.

Novel speed test for evaluation of badminton-specific movements.

PubMed

Madsen, Christian M; Karlsen, Anders; Nybo, Lars

2015-05-01

In this study, we developed a novel badminton-specific speed test (BST). The test was designed to mimic match play. The test starts in the center of the court and consists of 5 maximal actions to sensors located in each of the 4 corners of the court. The 20 actions are performed in randomized order as dictated by computer screen shots displayed 1 second after completion of the previous action. We assessed day-to-day variation in elite players, and specificity of the test was evaluated by comparing 30-m sprint performance and time to complete the BST in 20 elite players, 21 skilled players, and 20 age-matched physical active subjects (non-badminton players). Sprint performance was similar across groups, whereas the elite players were significantly (p ≤ 0.05) faster in the BST (total test time: 32.3 ± 1.1 seconds; average: 1.6 seconds per action) than the skilled (34.1 ± 2.0 seconds) and non-badminton players (35.7 ± 1.7 seconds). Day-to-day coefficient of variation (CV) of the BST was 0.7% for the elite players, whereas CV for repeated tests on the same day was 1.7% for elite, 2.6% for skilled, and 2.5% for non-badminton players. On this basis, we suggest that the BST may be valuable for evaluation of short-term maximal movement speed in badminton players. Thus, the BST seems to be sport specific, as it may discriminate between groups (elite, less trained players, and non-badminton players) with similar sprinting performance, and the low test-retest variation may allow for using the BST to evaluate longitudinal changes, for example, training effects or seasonal variations.

Comparison of the Physical and Technical Demands of Cricket Players During Training and Match-Play.

PubMed

Vickery, Will; Duffield, Rob; Crowther, Rian; Beakley, David; Blanch, Peter; Dascombe, Ben J

2018-03-01

Vickery, W, Duffield, R, Crowther, R, Beakley, D, Blanch, P, and Dascombe, BJ. Comparison of the physical and technical demands of cricket players during training and match-play. J Strength Cond Res 32(3): 821-829, 2018-This study aimed to determine which training method (net-based sessions or center-wicket simulations) currently used in national level and U19 male players cricket provided a more physical and technical match-specific training response. The heart rate, rating of perceived exertion, and movement patterns of 42 male cricket players were measured across the various training and match formats. Video analysis was coded retrospectively to quantify technical loads based on the cricket skills performed. Magnitude-based inferences were based on the standardization of effect and presented with ±90% confidence intervals. Regardless of playing position, differences in physiological demands between training modes and match-play were unclear, with the exception of higher heart rates in fielders during traditional net sessions (mean heart rate: d = -2.7 [-4.7 to -0.7]; 75% of maximum heart rate: d = -1.7 [-3.2 to -0.2]). Typically, the movement demands of center-wicket simulations were similar or greater than match-play, which was most evident in the distance traveled at a high intensity within each playing position (batsmen: d = 6.4 [3.7-9.2]; medium-fast bowlers: d = 1.71 [0.1-3.3]; spin bowlers: d = 6.5 [0.01-13.0]; fielders: d = 0.8 [-0.2 to 1.7]). The technical demands of traditional net cricket training exceeded that of a typical match for each playing position. Specifically, fast bowlers delivered a greater number of balls during net-bowling compared with a match (d = -2.2 [-3.6 to 0.9]). In conclusion, center-wicket simulations more closely matched the physical demands of a One-Day match within batsmen and spin bowlers, whereas traditional cricket training often exceeded match-specific demands.

Musician's cramp as manifestation of maladaptive brain plasticity: arguments from instrumental differences.

PubMed

Altenmüller, Eckart; Baur, Volker; Hofmann, Aurélie; Lim, Vanessa K; Jabusch, Hans-Christian

2012-04-01

Musician's cramp is a task-specific movement disorder that presents itself as muscular incoordination or loss of voluntary motor control of extensively trained movements while a musician is playing the instrument. It is characterized by task specificity and gender bias, affecting significantly more males than females. The etiology is multifaceted: a combination of a genetic predisposition, termed endophenotype, and behavioral triggering factors being the leading features for the manifestation of the disorder. We present epidemiological data from 591 musician patients from our outpatient clinic demonstrating an influence of fine-motor requirements on the manifestation of dystonia. Brass, guitar, and woodwind players were at greater risk than other instrumentalists. High temporospatial precision of movement patterns, synchronous demands on tonic and phasic muscular activation, in combination with fine-motor burdens of using the dominant hand in daily life activities, constitute as triggering factors for the disorder and may explain why different body parts are affected. © 2012 New York Academy of Sciences.

Understanding of empty container movement: A study on a bottleneck at an off-dock depot

NASA Astrophysics Data System (ADS)

Zain, Rosmaizura Mohd; Rahman, Mohd Nizam Ab; Nopiah, Zulkifli Mohd; Saibani, Nizaroyani

2014-09-01

Port not only function as connections between marine and land transportation but also as core business areas. In a port terminal, available space is limited, but the influx of container is growing. The off-dock depot is one of the key supply chain players that hold empty containers in the inventory. Therefore, this paper aims to identify the main factors of bottlenecks or congestion that hinder the rapid movement of empty containers from the off-dock depot to the customers. Thirty interviews were conducted with individuals who are key players in the container supply chain. The data were analyzed using Atlas.ti software and the analytic hierarchy process to rank the priority factors of bottlenecks. Findings show that several pertinent factors act as barriers to the key players in the container movement in the day-to-day operations. In future studies, strategies to overcome fragmentation in the container supply chain and logistics must be determined.

Spatial distribution of surface EMG on trapezius and lumbar muscles of violin and cello players in single note playing.

PubMed

Afsharipour, Babak; Petracca, Francesco; Gasparini, Mauro; Merletti, Roberto

2016-12-01

Musicians activate their muscles in different patterns, depending on their posture, the instrument being played, and their experience level. Bipolar surface electrodes have been used in the past to monitor such activity, but this method is highly sensitive to the location of the electrode pair. In this work, the spatial distribution of surface EMG (sEMG) of the right trapezius and right and left erector spinae muscles were studied in 16 violin players and 11 cello players. Musicians played their instrument one string at a time in sitting position with/without backrest support. A 64 sEMG electrode (16×4) grid, 10mm inter-electrode distance (IED), was placed over the middle and lower trapezius (MT and LT) of the bowing arm. Two 16×2 electrode grids (IED=10mm) were placed on the left and right erector spinae muscles. Subjects played each of the four strings of the instrument either in large (1bow/s) or detaché tip/tail (8bows/s) bowing in two sessions (two days). In each of two days, measurements were repeated after half an hour of exercise to see the effect of exercise on the muscle activity and signal stability. A "muscle activity index" (MAI) was defined as the spatial average of the segmented active region of the RMS map. Spatial maps were automatically segmented using the watershed algorithm and thresholding. Results showed that, for violin players, sliding the bow upward from the tip toward the tail results in a higher MAI for the trapezius muscle than a downward bow. On the contrary, in cello players, higher MAI is produced in the tail to tip movement. For both instruments, an increasing MAI in the trapezius was observed as the string position became increasingly lateral, from string 1 (most medial) toward string 4 (most lateral). Half an hour of performance did not cause significant differences between the signal quality and the MAI values measured before and after the exercise. The MAI of the left and right erector spinae was smaller in the case of backrest support, especially for violin players. Back muscles of violin and cello players were activated asymmetrically, specifically in fast movements (detaché tip/tail). These findings demonstrate the sensitivity and stability of the technique and justify more extensive investigation following this proof of concept. Copyright © 2016 Elsevier Ltd. All rights reserved.

Visual and skill effects on soccer passing performance, kinematics, and outcome estimations

PubMed Central

Basevitch, Itay; Tenenbaum, Gershon; Land, William M.; Ward, Paul

2015-01-01

The role of visual information and action representations in executing a motor task was examined from a mental representations approach. High-skill (n = 20) and low-skill (n = 20) soccer players performed a passing task to two targets at distances of 9.14 and 18.29 m, under three visual conditions: normal, occluded, and distorted vision (i.e., +4.0 corrective lenses, a visual acuity of approximately 6/75) without knowledge of results. Following each pass, participants estimated the relative horizontal distance from the target as the ball crossed the target plane. Kinematic data during each pass were also recorded for the shorter distance. Results revealed that performance on the motor task decreased as a function of visual information and task complexity (i.e., distance from target) regardless of skill level. High-skill players performed significantly better than low-skill players on both the actual passing and estimation tasks, at each target distance and visual condition. In addition, kinematic data indicated that high-skill participants were more consistent and had different kinematic movement patterns than low-skill participants. Findings contribute to the understanding of the underlying mechanisms required for successful performance in a self-paced, discrete and closed motor task. PMID:25784886

Soccer Injury Movement Screen (SIMS) Composite Score Is Not Associated With Injury Among Semi-Professional Soccer Players.

PubMed

McCunn, Robert; Fünten, Karen Aus der; Whalan, Matthew; Sampson, John A; Meyer, Tim

2018-05-08

Study Design Prospective cohort. Background The association between movement quality and injury is equivocal. No soccer-specific movement assessment has been prospectively investigated in relation to injury risk. Objectives To investigate the association between a soccer-specific movement quality assessment and injury risk among semi-professional soccer players. Methods Semi-professional soccer players (n=306) from 12 clubs completed the Soccer Injury Movement Screen (SIMS) during the pre-season period. Individual training/match exposure and non-contact time loss injuries were recorded prospectively for the entirety of the 2016 season. Relative risks (RR) were calculated, and presented with 90% confidence intervals (CI), for the SIMS composite and individual sub-test scores from generalized linear models with Poisson distribution offset for exposure. Results When considering non-contact time loss lower extremity injuries (primary level of analysis), there was a most likely trivial association with the SIMS composite score. Similarly, SIMS composite score demonstrated most likely to likely trivial associations to all injury categories included in the secondary level of analysis (non-contact time loss hip/groin, thigh, knee and ankle injuries). When considering hamstring strains and ankle sprains specifically (tertiary level of analysis) the SIMS composite score, again, demonstrated very likely trivial associations. A total of 262 non-contact time loss injuries were recorded. The overall (training and match exposure combined) incidence of non-contact time loss injury was 12/1000 hours. Conclusion The SIMS composite score demonstrated no association to any of the investigated categories of soccer-related injury. The SIMS composite score should not be used to group players into 'high' or 'low' risk groups. Level of Evidence Prognosis, level 4. J Orthop Sports Phys Ther, Epub 8 May 2018. doi:10.2519/jospt.2018.8037.

Predicting performance and injury resilience from movement quality and fitness scores in a basketball team over 2 years.

PubMed

McGill, Stuart M; Andersen, Jordan T; Horne, Arthur D

2012-07-01

The purpose of this study was to see if specific tests of fitness and movement quality could predict injury resilience and performance in a team of basketball players over 2 years (2 playing seasons). It was hypothesized that, in a basketball population, movement and fitness scores would predict performance scores and that movement and fitness scores would predict injury resilience. A basketball team from a major American university (N = 14) served as the test population in this longitudinal trial. Variables linked to fitness, movement ability, speed, strength, and agility were measured together with some National Basketball Association (NBA) combine tests. Dependent variables of performance indicators (such as games and minutes played, points scored, assists, rebounds, steal, and blocks) and injury reports were tracked for the subsequent 2 years. Results showed that better performance was linked with having a stiffer torso, more mobile hips, weaker left grip strength, and a longer standing long jump, to name a few. Of the 3 NBA combine tests administered here, only a faster lane agility time had significant links with performance. Some movement qualities and torso endurance were not linked. No patterns with injury emerged. These observations have implications for preseason testing and subsequent training programs in an attempt to reduce future injury and enhance playing performance.

Kinematic patterns underlying disguised movements: Spatial and temporal dissimilarity compared to genuine movement patterns.

PubMed

Helm, Fabian; Munzert, Jörn; Troje, Nikolaus F

2017-08-01

This study examined the kinematic characteristics of disguised movements by applying linear discriminant (LDA) and dissimilarity analyses to the motion data from 788 disguised and 792 non-disguised 7-m penalty throws performed by novice and expert handball field players. Results of the LDA showed that discrimination between type of throws (disguised vs. non-disguised) was more error-prone when throws were performed by experts (spatial: 4.6%; temporal: 29.6%) compared to novices (spatial: 1.0%; temporal: 20.2%). The dissimilarity analysis revealed significantly smaller spatial dissimilarities and variations between type of throws in experts compared to novices (p<0.001), but also showed that these spatial dissimilarities and variations increased significantly in both groups the closer the throws came to the moment of (predicted) ball release. In contrast, temporal dissimilarities did not differ significantly between groups. Thus, our data clearly demonstrate that expertise in disguising one's own action intentions results in an ability to perform disguised penalty throws that are highly similar to genuine throws. We suggest that this expertise depends mainly on keeping spatial dissimilarities small. However, the attempt to disguise becomes a challenge the closer one gets to the action outcome (i.e., ball release) becoming visible. Copyright © 2017 Elsevier B.V. All rights reserved.

The contribution of situational probability information to anticipatory skill.

PubMed

Farrow, Damian; Reid, Machar

2012-07-01

To determine the contribution of situational probability information to the anticipatory responses of skilled tennis players representative of two different stages of development. Participants were required to predict the location of tennis serves presented to them on a plasma touchscreen from the perspective of the receiver. Serves were sequenced into a series of games and sets with a score presented before each point, typical of a game of tennis. The game score was manipulated to provide advance probability information. The location of the serve for the first point of each game was always directed to the same location. A total of 12 service games consisting of 96 points were presented with interest in whether players would detect the relationship between the game score and resultant serve location. A 2×12 (age×service game) ANOVA with repeated measures on the second factor revealed a significant age by service game interaction for response time (F₁₁,₂₉₇=3.86, p<0.05, η(p)²=.12). The older players picked up the occurrence of the first point service pattern after the ninth service game whereas the younger, players did not. There were no significant response accuracy differences between the groups in relation to the first point. The findings highlight the important role of situational probability information, in addition to movement kinematics, for successful anticipatory performance and suggest that the pick-up of such information is not utilised by younger players. Copyright © 2012 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

The inter and intra rater reliability of the Netball Movement Screening Tool.

PubMed

Reid, Duncan A; Vanweerd, Rebecca J; Larmer, Peter J; Kingstone, Rachel

2015-05-01

To establish the inter- and intra-rater reliability of the Netball Movement Screening Tool, for screening adolescent female netball players. Inter- and intra-rater reliability study. Forty secondary school netball players were recruited to take part in the study. Twenty subjects were screened simultaneously and independently by two raters to ascertain inter-rater agreement. Twenty subjects were scored by rater one on two occasions, separated by a week, to ascertain intra-rater agreement. Inter and intra-rater agreement was assessed utilising the two-way mixed inter class correlation coefficient and weighted kappa statistics. No significant demographic differences were found between the inter and intra-rater groups of subjects. Inter class correlation coefficients' demonstrated excellent inter-rater (two-way mixed inter class correlation coefficients 0.84, standard error of measurement 0.25) and intra-rater (two-way mixed inter class correlation coefficients 0.96, standard error of measurement 0.13) reliability for the overall Netball Movement Screening Tool score and substantial-excellent (two-way mixed inter class correlation coefficients 1.0-0.65) inter-rater and substantial-excellent intra-rater (two-way mixed inter class correlation coefficients 0.96-0.79) reliability for the component scores of the Netball Movement Screening Tool. Kappa statistic showed substantial to poor inter-rater (k=0.75-0.32) and intra-rater (k=0.77-0.27) agreement for individual tests of the NMST. The Netball Movement Screening Tool may be a reliable screening tool for adolescent netball players; however the individual test scores have low reliability. The screening tool can be administered reliably by raters with similar levels of training in the tool but variable clinical experience. On-going research needs to be undertaken to ascertain whether the Netball Movement Screening Tool is a valid tool in ascertaining increased injury risk for netball players. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Wearable flex sensor system for multiple badminton player grip identification

NASA Astrophysics Data System (ADS)

Jacob, Alvin; Zakaria, Wan Nurshazwani Wan; Tomari, Mohd Razali Bin Md; Sek, Tee Kian; Suberi, Anis Azwani Muhd

2017-09-01

This paper focuses on the development of a wearable sensor system to identify the different types of badminton grip that is used by a player during training. Badminton movements and strokes are fast and dynamic, where most of the involved movement are difficult to identify with the naked eye. Also, the usage of high processing optometric motion capture system is expensive and causes computational burden. Therefore, this paper suggests the development of a sensorized glove using flex sensor to measure a badminton player's finger flexion angle. The proposed Hand Monitoring Module (HMM) is connected to a personal computer through Bluetooth to enable wireless data transmission. The usability and feasibility of the HMM to identify different grip types were examined through a series of experiments, where the system exhibited 70% detection ability for the five different grip type. The outcome plays a major role in training players to use the proper grips for a badminton stroke to achieve a more powerful and accurate stroke execution.

Scapular Resting Position and Gleno-Humeral Movement Dysfunction in Asymptomatic Racquet Players: A Case-Control Study

PubMed Central

Shimpi, Apurv P.; Bhakti, Shah; Roshni, Karnik; Rairikar, Savita A.; Shyam, Ashok; Sancheti, Parag K.

2015-01-01

Background: Racquet sports, especially lawn tennis and badminton have been gaining popularity in Asian countries like India. With this increase in popularity, the injury rate in the sport has also increased. Objectives: The study will help detect the presence of gleno-humeral movement dysfunction and scapular resting position abnormality in asymptomatic racquet players, thus providing basis for screening the players and allow the clinician to determine if the asymmetry is a normal adaptation in the player or an abnormal change associated with injury. Materials and Methods: 46 asymptomatic professional players were divided into a study group of 23 players (16 tennis and 7 badminton) and control group of 23 football players. Assessment of passive gleno-humeral range of motion and distance of spine and inferior angle of scapula from corresponding spinous process were measured bilaterally and between groups. Results: There was statistically significant reduction in range of internal rotation (62.17 ± 8.09), extension (39.78 ± 4.12) and an increase in the external rotation (106.95 ± 7.49) of dominant compared to non-dominant arm of racquet players and a statistically significant decrease in internal rotation (78.69 ± 10.24), extension (44.78 ± 3.19), adduction (37.39 ± 6.54) and an increase in external rotation (102.6 ± 5.19) of dominant arm of racquet players compared to football players. Study also showed statistically significant increase in the spino-scapular distance at the level of inferior angle of scapula (10.23 ± 1.43) on dominant side compared to non-dominant. Conclusions: The dominant side scapula of asymptomatic racquet players showed increased external rotation and elevation as compared to the non-dominant side. Also, reduced shoulder internal rotation, extension and adduction and gain in shoulder external rotation was observed on the dominant side of racquet players when compared to the control group. PMID:26715968

Scapular Resting Position and Gleno-Humeral Movement Dysfunction in Asymptomatic Racquet Players: A Case-Control Study.

PubMed

Shimpi, Apurv P; Bhakti, Shah; Roshni, Karnik; Rairikar, Savita A; Shyam, Ashok; Sancheti, Parag K

2015-12-01

Racquet sports, especially lawn tennis and badminton have been gaining popularity in Asian countries like India. With this increase in popularity, the injury rate in the sport has also increased. The study will help detect the presence of gleno-humeral movement dysfunction and scapular resting position abnormality in asymptomatic racquet players, thus providing basis for screening the players and allow the clinician to determine if the asymmetry is a normal adaptation in the player or an abnormal change associated with injury. 46 asymptomatic professional players were divided into a study group of 23 players (16 tennis and 7 badminton) and control group of 23 football players. Assessment of passive gleno-humeral range of motion and distance of spine and inferior angle of scapula from corresponding spinous process were measured bilaterally and between groups. There was statistically significant reduction in range of internal rotation (62.17 ± 8.09), extension (39.78 ± 4.12) and an increase in the external rotation (106.95 ± 7.49) of dominant compared to non-dominant arm of racquet players and a statistically significant decrease in internal rotation (78.69 ± 10.24), extension (44.78 ± 3.19), adduction (37.39 ± 6.54) and an increase in external rotation (102.6 ± 5.19) of dominant arm of racquet players compared to football players. Study also showed statistically significant increase in the spino-scapular distance at the level of inferior angle of scapula (10.23 ± 1.43) on dominant side compared to non-dominant. The dominant side scapula of asymptomatic racquet players showed increased external rotation and elevation as compared to the non-dominant side. Also, reduced shoulder internal rotation, extension and adduction and gain in shoulder external rotation was observed on the dominant side of racquet players when compared to the control group.

Basketball Teams as Strategic Networks

PubMed Central

Fewell, Jennifer H.; Armbruster, Dieter; Ingraham, John; Petersen, Alexander; Waters, James S.

2012-01-01

We asked how team dynamics can be captured in relation to function by considering games in the first round of the NBA 2010 play-offs as networks. Defining players as nodes and ball movements as links, we analyzed the network properties of degree centrality, clustering, entropy and flow centrality across teams and positions, to characterize the game from a network perspective and to determine whether we can assess differences in team offensive strategy by their network properties. The compiled network structure across teams reflected a fundamental attribute of basketball strategy. They primarily showed a centralized ball distribution pattern with the point guard in a leadership role. However, individual play-off teams showed variation in their relative involvement of other players/positions in ball distribution, reflected quantitatively by differences in clustering and degree centrality. We also characterized two potential alternate offensive strategies by associated variation in network structure: (1) whether teams consistently moved the ball towards their shooting specialists, measured as “uphill/downhill” flux, and (2) whether they distributed the ball in a way that reduced predictability, measured as team entropy. These network metrics quantified different aspects of team strategy, with no single metric wholly predictive of success. However, in the context of the 2010 play-offs, the values of clustering (connectedness across players) and network entropy (unpredictability of ball movement) had the most consistent association with team advancement. Our analyses demonstrate the utility of network approaches in quantifying team strategy and show that testable hypotheses can be evaluated using this approach. These analyses also highlight the richness of basketball networks as a dataset for exploring the relationships between network structure and dynamics with team organization and effectiveness. PMID:23139744

Basketball teams as strategic networks.

PubMed

Fewell, Jennifer H; Armbruster, Dieter; Ingraham, John; Petersen, Alexander; Waters, James S

2012-01-01

We asked how team dynamics can be captured in relation to function by considering games in the first round of the NBA 2010 play-offs as networks. Defining players as nodes and ball movements as links, we analyzed the network properties of degree centrality, clustering, entropy and flow centrality across teams and positions, to characterize the game from a network perspective and to determine whether we can assess differences in team offensive strategy by their network properties. The compiled network structure across teams reflected a fundamental attribute of basketball strategy. They primarily showed a centralized ball distribution pattern with the point guard in a leadership role. However, individual play-off teams showed variation in their relative involvement of other players/positions in ball distribution, reflected quantitatively by differences in clustering and degree centrality. We also characterized two potential alternate offensive strategies by associated variation in network structure: (1) whether teams consistently moved the ball towards their shooting specialists, measured as "uphill/downhill" flux, and (2) whether they distributed the ball in a way that reduced predictability, measured as team entropy. These network metrics quantified different aspects of team strategy, with no single metric wholly predictive of success. However, in the context of the 2010 play-offs, the values of clustering (connectedness across players) and network entropy (unpredictability of ball movement) had the most consistent association with team advancement. Our analyses demonstrate the utility of network approaches in quantifying team strategy and show that testable hypotheses can be evaluated using this approach. These analyses also highlight the richness of basketball networks as a dataset for exploring the relationships between network structure and dynamics with team organization and effectiveness.

Some anthropologic characteristics of elite female handball players at different playing positions.

PubMed

Rogulj, Nenad; Srhoj, Vatromir; Nazor, Mirjana; Srhoj, Ljerka; Cavala, Marijana

2005-12-01

Differences in motor and psychologic variables according to playing positions were analyzed in a sample of 53 elite female handball players, members of junior and senior national team. Motor status included 8 variables for assessment of explosive strength of landing and throwing, agility, speed strength, movement frequency, and flexibility. Psychologic status was analyzed through 4 dimensions according to Eysenck: extroversion, psychotic behavior, neurotic behavior, and lie. The anthropologic features analyzed showed statistically significant differences. Considering motor abilities, differences were recorded in the variables for assessment of speed strength, agility and leg movement frequency, where wings predominated, whereas goalkeepers showed predominance in flexibility. In psychologic status, differences were present in the variable for assessment of extroversion, which was most pronounced in wings, whereas psychotic behavior was more expressed in those at pivot position. The differences were primarily consequential to the selection of players of a specific anthropologic profile for particular playing positions. The hypothesis of the impact of kinesiologic specificities of a particular playing position on the formation of the players' anthropologic profile should be scientifically tested. Study results may found application in training and contest practice, especially in forming anthropologic models for particular positions during the process of player selection.

Physiological characteristics of elite and sub-elite badminton players.

PubMed

Ooi, Cheong Hwa; Tan, Albert; Ahmad, Azwari; Kwong, Kien Weng; Sompong, Ruji; Ghazali, Khairul Aswadi Mohd; Liew, Swee Lee; Chai, Wen Jin; Thompson, Martin William

2009-12-01

The aims of this study were to establish the physical and physiological attributes of elite and sub-elite Malaysian male badminton players and to determine whether these attributes discriminate elite players from sub-elite players. Measurements and tests of basic anthropometry, explosive power, anaerobic recovery capacity, badminton-specific movement agility, maximum strength, and aerobic capacity were conducted on two occasions, separated by at least one day. The elite (n = 12) and sub-elite (n = 12) players' characteristics were, respectively: mean age 24.6 years (s = 3.7) and 20.5 years (s = 0.7); mass 73.2 kg (s = 7.6) and 62.7 kg (s = 4.2); stature 1.76 m (s = 0.07) and 1.71 m (s = 0.05); body fat 12.5% (s = 4.8) and 9.5% (s = 3.4); estimated VO(2max) 56.9 ml . kg(-1) . min(-1) (s = 3.7) and 59.5 ml . kg(-1) . min(-1) (s = 5.2). The elite players had greater maximum absolute strength in one-repetition maximum bench press (P = 0.015) compared with the sub-elite players. There were significant differences in instantaneous lower body power estimated from vertical jump height between the elite and sub-elite groups (P < 0.01). However, there was no significant difference between groups in shuttle run tests and on-court badminton-specific movement agility tests. Our results show that elite Malaysian male badminton players are taller, heavier, and stronger than their sub-elite counterparts. The test battery, however, did not allow us to discriminate between the elite and sub-elite players, suggesting that at the elite level tactical knowledge, technical skills, and psychological readiness could be of greater importance.

How do expert soccer players encode visual information to make decisions in simulated game situations?

PubMed

Poplu, Gérald; Ripoll, Hubert; Mavromatis, Sébastien; Baratgin, Jean

2008-09-01

The aim of this study was to determine what visual information expert soccer players encode when they are asked to make a decision. We used a repetition-priming paradigm to test the hypothesis that experts encode a soccer pattern's structure independently of the players' physical characteristics (i.e., posture and morphology). The participants were given either realistic (digital photos) or abstract (three-dimensional schematic representations) soccer game patterns. The results showed that the experts benefited from priming effects regardless of how abstract the stimuli were. This suggests that an abstract representation of a realistic pattern (i.e., one that does not include visual information related to the players'physical characteristics) is sufficient to activate experts'specific knowledge during decision making. These results seem to show that expert soccer players encode and store abstract representations of visual patterns in memory.

Balance disorders caused by running and jumping occurring in young basketball players.

PubMed

Struzik, Artur; Zawadzki, Jerzy; Pietraszewski, Bogdan

2015-01-01

Body balance, as one of the coordination abilities,is a desirable variable for basketball players as regards the necessity of efficient responses in constantly changing situations on a basketball court. The aim of this study was to check whether physical activity in the form of running and jumping influences variables characterizing the process of keeping body balance of a basketball player in the standing position. The research was conducted on 11 young basketball players. The measurements were taken with a Kistler force plate. Apart from commonly registered COP displacements, an additional variable describing the process of keeping body balance by a basketball player was ankle joint stiffness on the basis of which an "Index of Balance-Stiffness" (IB-S) was created. Statistically significant differences were obtained for the maximum COP displacements and ankle joint stiffness between measurements of balance in the standing position before and after the employed movement tasks whereas there were no statistically significant differences for the aforementioned variables describing the process of keeping balance between measurements after running and after jumping. The research results indicate that the employed movement activities brought about significant changes in the process of keeping balance of basketball player in the standing position which, after the run performed, remain on a similar level to the series of jumps being performed. The authors attempted to establish an index based on the stiffness which yields a possibility to perceive each basketball player as an individual person in the process of keeping balance.

Movement Demands of Elite U20 International Rugby Union Players

PubMed Central

Drawer, Scott; Eager, Robin; Taylor, Neil; Cook, Christian

2016-01-01

The purpose of this study was to quantify movement demands of elite international age grade (U20) rugby union players during competitive tournament match play. Forty elite professional players from an U20 international performance squad were monitored using 10Hz global positioning systems (GPS) during 15 international tournament matches during the 2014/15 and 2015/16 seasons. Data on distances, velocities, accelerations, decelerations, high metabolic load (HML) distance and efforts, and number of sprints were derived. Data files from players who played over 60 min (n = 161) were separated firstly into Forwards and Backs, and more specifically into six positional groups; FR—Front Row (prop & hooker), SR—Second Row, BR—Back Row (Flankers & No.8), HB—Half Backs (scrum half & outside half), MF—Midfield (centres), B3 –Back Three (wings & full back) for match analysis. Analysis revealed significant differences between forwards and backs positions. Backs scored higher on all variables measured with the exception of number of moderate accelerations, decelerations (no difference). The centres covered the greatest total distance with the front row covering the least (6.51 ± 0.71 vs 4.97 ± 0.75 km, p < 0.001). The front row also covered the least high speed running (HSR) distance compared to the back three (211.6 ± 112.7 vs 728.4 ± 150.2 m, p < 0.001) who covered the most HSR distance, affirming that backs cover greater distances but forwards have greater contact loads. These findings highlight for the first time differences in the movement characteristics of elite age grade rugby union players specific to positional roles. PMID:27055230

Movement Demands of Elite U20 International Rugby Union Players.

PubMed

Cunningham, Daniel; Shearer, David A; Drawer, Scott; Eager, Robin; Taylor, Neil; Cook, Christian; Kilduff, Liam P

2016-01-01

The purpose of this study was to quantify movement demands of elite international age grade (U20) rugby union players during competitive tournament match play. Forty elite professional players from an U20 international performance squad were monitored using 10 Hz global positioning systems (GPS) during 15 international tournament matches during the 2014/15 and 2015/16 seasons. Data on distances, velocities, accelerations, decelerations, high metabolic load (HML) distance and efforts, and number of sprints were derived. Data files from players who played over 60 min (n = 161) were separated firstly into Forwards and Backs, and more specifically into six positional groups; FR--Front Row (prop & hooker), SR--Second Row, BR--Back Row (Flankers & No.8), HB--Half Backs (scrum half & outside half), MF--Midfield (centres), B3--Back Three (wings & full back) for match analysis. Analysis revealed significant differences between forwards and backs positions. Backs scored higher on all variables measured with the exception of number of moderate accelerations, decelerations (no difference). The centres covered the greatest total distance with the front row covering the least (6.51 ± 0.71 vs 4.97 ± 0.75 km, p < 0.001). The front row also covered the least high speed running (HSR) distance compared to the back three (211.6 ± 112.7 vs 728.4 ± 150.2 m, p < 0.001) who covered the most HSR distance, affirming that backs cover greater distances but forwards have greater contact loads. These findings highlight for the first time differences in the movement characteristics of elite age grade rugby union players specific to positional roles.

Characteristics of upper extremity's muscle strength in Turkish national wheelchair basketball players team.

PubMed

Akınoğlu, Bihter; Kocahan, Tuğba

2017-02-01

The objective of this study was to reveal characteristics of muscle strength of upper extremities of wheelchair (WC) basketball players and to ensure more-specific training program preparation. Isokinetic muscle strength of 12 WC basketball players were assessed by ISOMED 2000 device. The assessment protocol was evaluated at 60°/sec velocity with 5 times repeated force and at 240°/sec with 15 times repeated force. This protocol was carried out individually for shoulder flexion-extension and wrist flexion-extension movements at the right and left extremities. The flexion/extension ratio was determined to be outside of the ratios accepted as normal for primarily shoulder joint and for wrist joint. The extension movement was stronger than flexion movement in the shoulders at both velocities and the flexion movement was stronger than ex-tension movement in the wrist. The repeat times where the peak torque occurred were 2-3 repeats at 60°/sec velocity during flexion and extension movements for the wrist and shoulders, and the peak torque occurred at an average of 5-6 repeats in the shoulders at 240°/sec velocity and it occurred at 3-4 repeats in the wrist. The angles where the peak torque of the shoulder flexion and extension occurred varied between 80°-115° at both velocities, and it varied between 5°-30° angles for the wrist. As this study revealed, determination of muscle strength characteristics of WC athletes and especially using objective isokinetic devices will guide the planning of the appropriate training and exercise programs and preventing sports injuries in long term.

Relations between basic and specific motor abilities and player quality of young basketball players.

PubMed

Marić, Kristijan; Katić, Ratko; Jelicić, Mario

2013-05-01

Subjects from 5 first league clubs from Herzegovina were tested with the purpose of determining the relations of basic and specific motor abilities, as well as the effect of specific abilities on player efficiency in young basketball players (cadets). A battery of 12 tests assessing basic motor abilities and 5 specific tests assessing basketball efficiency were used on a sample of 83 basketball players. Two significant canonical correlations, i.e. linear combinations explained the relation between the set of twelve variables of basic motor space and five variables of situational motor abilities. Underlying the first canonical linear combination is the positive effect of the general motor factor, predominantly defined by jumping explosive power, movement speed of the arms, static strength of the arms and coordination, on specific basketball abilities: movement efficiency, the power of the overarm throw, shooting and passing precision, and the skill of handling the ball. The impact of basic motor abilities of precision and balance on specific abilities of passing and shooting precision and ball handling is underlying the second linear combination. The results of regression correlation analysis between the variable set of specific motor abilities and game efficiency have shown that the ability of ball handling has the largest impact on player quality in basketball cadets, followed by shooting precision and passing precision, and the power of the overarm throw.

Optimising technical skills and physical loading in small-sided basketball games.

PubMed

Klusemann, Markus J; Pyne, David B; Foster, Carl; Drinkwater, Eric J

2012-01-01

Differences in physiological, physical, and technical demands of small-sided basketball games related to the number of players, court size, and work-to-rest ratios are not well characterised. A controlled trial was conducted to compare the influence of number of players (2v2/4v4), court size (half/full court) and work-to-rest ratios (4x2.5 min/2x5 min) on the demands of small-sided games. Sixteen elite male and female junior players (aged 15-19 years) completed eight variations of a small-sided game in randomised order over a six-week period. Heart rate responses and rating of perceived exertion (RPE) were measured to assess the physiological load. Movement patterns and technical elements were assessed by video analysis. There were ∼60% more technical elements in 2v2 and ∼20% more in half court games. Heart rate (86 ± 4% & 83 ± 5% of maximum; mean ± SD) and RPE (8 ± 2 & 6 ± 2; scale 1-10) were moderately higher in 2v2 than 4v4 small-sided games, respectively. The 2v2 format elicited substantially more sprints (36 ±12%; mean ±90% confidence limits) and high intensity shuffling (75 ±17%) than 4v4. Full court games required substantially more jogging (9 ±6%) compared to half court games. Fewer players in small-sided basketball games substantially increases the technical, physiological and physical demands.

Discriminating Talent Identified Junior Australian Footballers Using a Fundamental Gross Athletic Movement Assessment.

PubMed

Woods, Carl T; Banyard, Harry G; McKeown, Ian; Fransen, Job; Robertson, Sam

2016-09-01

Talent identification (TID) is a pertinent component of the sports sciences, affording practitioners the opportunity to target developmental interventions to a select few; optimising financial investments. However, TID is multi-componential, requiring the recognition of immediate and prospective performance. The measurement of athletic movement skill may afford practitioners insight into the latter component given its augmented relationship with functional sport specific qualities. It is currently unknown whether athletic movement skill is a discriminant quality in junior Australian football (AF). This study aimed to discriminate talent identified junior AF players from their non-talent identified counterparts using a fundamental gross athletic movement assessment. From a total of 50 under 18 (U18) AF players; two groups were classified a priori based on selection level; talent identified (n = 25; state academy representatives) and non-talent identified (n = 25; state-based competition representatives). Players performed a fundamental gross athletic movement assessment based on the Athletic Ability Assessment (AAA), consisting of an overhead squat, double lunge (left and right legs), single leg Romanian deadlift (left and right legs), and a push up (six movement criterions). Movements were scored across three assessment points using a three-point scale (resulting in a possible score of nine for each movement). A multivariate analysis of variance revealed significant between group effects on four of the six movement criterions (d = 0.56 - 0.87; p = 0.01 - 0.02). Binary logistic regression models and a receiver operating characteristic curve inspection revealed that the overhead squat score provided the greatest group discrimination (β(SE) = -0.89(0.44); p < 0.05), with a score of 4.5 classifying 64% and 88% of the talent identified and non-talent identified groups, respectively. Results support the integration of this assessment into contemporary talent identification approaches in junior AF, as it may provide coaches with insight into a juniors developmental potential.

Determinants of the half-turn with the ball in sub-elite youth soccer players.

PubMed

Zago, Matteo; Codari, Marina; Grilli, Massimo; Bellistri, Giuseppe; Lovecchio, Nicola; Sforza, Chiarella

2016-06-01

We explored the biomechanics of the 180° change-of-direction with the ball (half-turn) in soccer. We aimed at identifying movement strategies which enhance the players' half-turning performance, by characterising technique kinematics and understanding the structure of biomechanical and anthropometrics variables. Ten Under-13 sub-elite male players were recorded with an optoelectronic motion analyser while performing a 5-m straight dribbling followed by a half-turn with the sole. Joints kinematics differences between faster and slower trials were found in support-side hip rotation, driving-side hip adduction, trunk flexion and rotation, and arms abduction. To unveil the data-set structure, a principal component (PC) analysis and a stepwise linear discriminant analysis were performed using 30 biomechanical parameters and four anthropometric variables for each trial. Seven retained PCs explained 79% of the overall variability, featuring combinations of original variables that help in understanding the factors facilitating fast half-turns: keeping short steps, minimising lateral and forward body movements, and centre-of-mass lowering, even with ample lower limbs ranges of motion (RoM); abducting the upper limbs while limiting trunk flexion and pelvic inclination RoM. Balance and task-constrained exercises may be proposed to improve this technique. Moreover, a quantitative knowledge of the movement structure could give coaches objective insights to better instruct young players.

The effect of stimulus intensity on response time and accuracy in dynamic, temporally constrained environments.

PubMed

Causer, J; McRobert, A P; Williams, A M

2013-10-01

The ability to make accurate judgments and execute effective skilled movements under severe temporal constraints are fundamental to elite performance in a number of domains including sport, military combat, law enforcement, and medicine. In two experiments, we examine the effect of stimulus strength on response time and accuracy in a temporally constrained, real-world, decision-making task. Specifically, we examine the effect of low stimulus intensity (black) and high stimulus intensity (sequin) uniform designs, worn by teammates, to determine the effect of stimulus strength on the ability of soccer players to make rapid and accurate responses. In both field- and laboratory-based scenarios, professional soccer players viewed developing patterns of play and were required to make a penetrative pass to an attacking player. Significant differences in response accuracy between uniform designs were reported in laboratory- and field-based experiments. Response accuracy was significantly higher in the sequin compared with the black uniform condition. Response times only differed between uniform designs in the laboratory-based experiment. These findings extend the literature into a real-world environment and have significant implications for the design of clothing wear in a number of domains. © 2012 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Mechanisms for anterior cruciate ligament injuries in badminton.

PubMed

Kimura, Yuka; Ishibashi, Yasuyuki; Tsuda, Eiichi; Yamamoto, Yuji; Tsukada, Harehiko; Toh, Satoshi

2010-12-01

A high incidence of anterior cruciate ligament (ACL) injuries related to sports activities has been reported; however, the injury situation of ACL injury in badminton has not been elucidated. This study investigated the mechanism of ACL injury in badminton using a questionnaire. Information on injury mechanism was gathered from interviews with six male and 15 female badminton players who received a non-contact ACL injury playing badminton and underwent ACL reconstruction. The most common injury mechanism (10 of 21 injuries) was single-leg landing after overhead stroke. Nine of 10 players had injured the knee opposite to the racket-hand side. The second most frequent injury mechanism (eight of 21 injuries) was plant-and-cut while side-stepping or backward stepping. All eight players injured the knee of the racket-hand side. Eleven injuries occurred in the rear court, and six of the 11 injuries occurred during single-leg landing after an overhead stroke. The knee opposite to the racket-hand side tended to sustain the ACL injuries during single-leg landing after a backhand overhead stroke, whereas the knee of the racket-hand side tended to be injured by plant-and-cut during side or backward stepping. These injury patterns appear to be due to specific movements during badminton.

Biomechanical Differences of Multidirectional Jump Landings Among Female Basketball and Soccer Players.

PubMed

Taylor, Jeffrey B; Ford, Kevin R; Schmitz, Randy J; Ross, Scott E; Ackerman, Terry A; Shultz, Sandra J

2017-11-01

Taylor, JB, Ford, KR, Schmitz, RJ, Ross, SE, Ackerman, TA, and Shultz, SJ. Biomechanical differences of multidirectional jump landings among female basketball and soccer players. J Strength Cond Res 31(11): 3034-3045, 2017-Anterior cruciate ligament (ACL) injury prevention programs are less successful in basketball than soccer and may be due to distinct movement strategies that these athletes develop from sport-specific training. The purpose of this study was to identify biomechanical differences between female basketball and soccer players during multidirectional jump landings. Lower extremity biomechanics of 89 female athletes who played competitive basketball (n = 40) or soccer (n = 49) at the middle- or high-school level were analyzed with 3-dimensional motion analysis during a drop vertical jump, double- (SAG-DL) and single-leg forward jump (SAG-SL), and double- (FRONT-DL) and single-leg (FRONT-SL) lateral jump. Basketball players landed with either less hip or knee, or both hip and knee excursion during all tasks (p ≤ 0.05) except for the SAGSL task, basketball players landed with greater peak hip flexion angles (p = 0.04). The FRONT-SL task elicited the most distinct sport-specific differences, including decreased hip adduction (p < 0.001) angles, increased hip internal rotation (p = 0.003), and increased relative knee external rotation (p = 0.001) excursions in basketball players. In addition, the FRONT-SL task elicited greater forces in knee abduction (p = 0.003) and lesser forces in hip adduction (p = 0.001) and knee external rotation (p < 0.001) in basketball players. Joint energetics were different during the FRONT-DL task, as basketball players exhibited less sagittal plane energy absorption at the hip (p < 0.001) and greater hip (p < 0.001) and knee (p = 0.001) joint stiffness. Sport-specific movement strategies were identified during all jump landing tasks, such that soccer players exhibited a more protective landing strategy than basketball players, justifying future efforts toward sport-specific ACL injury prevention programs.

Effects of emphasising opposition and cooperation on collective movement behaviour during football small-sided games.

PubMed

Gonçalves, B; Marcelino, R; Torres-Ronda, L; Torrents, C; Sampaio, J

2016-07-01

Optimizing collective behaviour helps to increase performance in mutual tasks. In team sports settings, the small-sided games (SSG) have been used as key context tools to stress out the players' awareness about their in-game required behaviours. Research has mostly described these behaviours when confronting teams have the same number of players, disregarding the frequent situations of low and high inequality. This study compared the players' positioning dynamics when manipulating the number of opponents and teammates during professional and amateur football SSG. The participants played 4v3, 4v5 and 4v7 games, where one team was confronted with low-superiority, low- and high-inferiority situations, and their opponents with low-, medium- and high-cooperation situations. Positional data were used to calculate effective playing space and distances from each player to team centroid, opponent team centroid and nearest opponent. Outcomes suggested that increasing the number of opponents in professional teams resulted in moderate/large decrease in approximate entropy (ApEn) values to both distance to team and opponent team centroid (i.e., the variables present higher regularity/predictability pattern). In low-cooperation game scenarios, the ApEn in amateurs' tactical variables presented a moderate/large increase. The professional teams presented an increase in the distance to nearest opponent with the increase of the cooperation level. Increasing the number of opponents was effective to overemphasise the need to use local information in the positioning decision-making process from professionals. Conversely, amateur still rely on external informational feedback. Increasing the cooperation promoted more regularity in spatial organisation in amateurs and emphasise their players' local perceptions.

CONSISTENCY OF FIELD-BASED MEASURES OF NEUROMUSCULAR CONTROL USING FORCE PLATE DIAGNOSTICS IN ELITE MALE YOUTH SOCCER PLAYERS

PubMed Central

READ, PAUL; OLIVER, JON L.; DE STE CROIX, MARK B.A.; MYER, GREGORY D.; LLOYD, RHODRI S.

2016-01-01

Deficits in neuromuscular control during movement patterns such as landing are suggested pathomechanics that underlie sport-related injury. A common mode of assessment is measurement of landing forces during jumping tasks; however, these measures have been used less frequently in male youth soccer players and reliability data is sparse. The aim of this study was to examine the reliability of a field-based neuromuscular control screening battery using force plate diagnostics in this cohort. Twenty six pre-peak height velocity (PHV) and twenty five post-PHV elite male youth soccer players completed a drop vertical jump (DVJ), single leg 75% horizontal hop and stick (75%HOP) and single leg countermovement jump (SLCMJ). Measures of peak landing vertical ground reaction force (pVGRF), time to stabilisation (TTS), time to pVGRF, and pVGRF asymmetry were recorded. A test, re-test design was used and reliability statistics included: change in mean, intraclass correlation coefficient (ICC) and coefficient of variation (CV). No significant differences in mean score were reported for any of the assessed variables between test sessions. In both groups, pVGRF and asymmetry during the 75%HOP and SLCMJ demonstrated largely acceptable reliability (CV ≤ 10%). Greater variability was evident in DVJ pVGRF and all other assessed variables, across the three protocols (CV range = 13.8 – 49.7%). ICC values ranged from small to large and were generally higher in the post-PHV players. The results of this study suggest that pVGRF and asymmetry can be reliably assessed using a 75%HOP and SLCMJ in this cohort. These measures could be utilized to support a screening battery for elite male youth soccer players and for test re-test comparison. PMID:27075641

Asymmetry during preseason Functional Movement Screen testing is associated with injury during a junior Australian football season.

PubMed

Chalmers, Samuel; Fuller, Joel T; Debenedictis, Thomas A; Townsley, Samuel; Lynagh, Matthew; Gleeson, Cara; Zacharia, Andrew; Thomson, Stuart; Magarey, Mary

2017-07-01

The Functional Movement Screen (FMS) is a popular screening tool, however, the postulated relationship between prospective injury and FMS scoring remains sparsely explored in adolescent athletes. The aim of the study was to examine the association between pre-season FMS scores and injuries sustained during one regular season competition in elite adolescent Australian football players. Prospective cohort study. 237 elite junior Australian football players completed FMS testing during the late pre-season phase and had their weekly playing status monitored during the regular season. The definition of an injury was 'a trauma which caused a player to miss a competitive match'. The median composite FMS score was 14 (mean=13.5±2.3). An apriori analysis revealed that the presence of ≥1 asymmetrical sub-test was associated with a moderate increase in the risk of injury (hazard ratio=2.2 [1.0-4.8]; relative risk=1.9; p=0.047; sensitivity=78.4%; specificity=41.0%). Notably, post-hoc analysis identified that the presence of ≥2 asymmetrical sub-tests was associated with an even greater increase in risk of prospective injury (hazard ratio=3.7 [1.6-8.6]; relative risk=2.8; p=0.003; sensitivity=66.7%; specificity=78.0%). Achieving a composite score of ≤14 did not substantially increase the risk of prospective injury (hazard ratio=1.1 [0.5-2.1]; p=0.834). Junior Australian football players demonstrating asymmetrical movement during pre-season FMS testing were more likely to sustain an injury during the regular season than players without asymmetry. Findings suggest that the commonly reported composite FMS threshold score of ≤14 was not associated with injury in elite junior AF players. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Preseason Functional Movement Screen Component Tests Predict Severe Contact Injuries in Professional Rugby Union Players.

PubMed

Tee, Jason C; Klingbiel, Jannie F G; Collins, Robert; Lambert, Mike I; Coopoo, Yoga

2016-11-01

Tee, JC, Klingbiel, JFG, Collins, R, Lambert, MI, and Coopoo, Y. Preseason Functional Movement Screen component tests predict severe contact injuries in professional rugby union players. J Strength Cond Res 30(11): 3194-3203, 2016-Rugby union is a collision sport with a relatively high risk of injury. The ability of the Functional Movement Screen (FMS) or its component tests to predict the occurrence of severe (≥28 days) injuries in professional players was assessed. Ninety FMS test observations from 62 players across 4 different time periods were compared with severe injuries sustained during 6 months after FMS testing. Mean composite FMS scores were significantly lower in players who sustained severe injury (injured 13.2 ± 1.5 vs. noninjured 14.5 ± 1.4, Effect Size = 0.83, large) because of differences in in-line lunge (ILL) and active straight leg raise scores (ASLR). Receiver-operated characteristic curves and 2 × 2 contingency tables were used to determine that ASLR (cut-off 2/3) was the injury predictor with the greatest sensitivity (0.96, 95% confidence interval [CI] = 0.79-1.0). Adding the ILL in combination with ASLR (ILL + ASLR) improved the specificity of the injury prediction model (ASLR specificity = 0.29, 95% CI = 0.18-0.43 vs. ASLR + ILL specificity = 0.53, 95% CI = 0.39-0.66, p ≤ 0.05). Further analysis was performed to determine whether FMS tests could predict contact and noncontact injuries. The FMS composite score and various combinations of component tests (deep squat [DS] + ILL, ILL + ASLR, and DS + ILL + ASLR) were all significant predictors of contact injury. The FMS composite score also predicted noncontact injury, but no component test or combination thereof produced a similar result. These findings indicate that low scores on various FMS component tests are risk factors for injury in professional rugby players.

Effects of Six Weeks of Medicine Ball Training on Throwing Velocity, Throwing Precision, and Isokinetic Strength of Shoulder Rotators in Female Handball Players.

PubMed

Raeder, Christian; Fernandez-Fernandez, Jaime; Ferrauti, Alexander

2015-07-01

The aim of this study was to investigate the effects of 6 weeks of medicine ball training (MBT) on throwing velocity, throwing precision, and isokinetic strength of shoulder rotators in competitive female handball players. Twenty-eight players (mean ± SD; age: 20.8 ± 3.3 years, height: 170.5 ± 5.6 cm, body mass: 65.2 ± 8.0 kg) were randomly assigned to an MBT group (TG; n = 15) and a control group (CG; n = 13). TG performed a supervised MBT program, 3 times a week for a total of 6 weeks, focusing on handball-specific movement patterns. Both groups, TG and CG, also conducted a supervised shoulder injury prevention program with elastic tubes, as part of the warm-up, finishing with regular handball throws. Results showed a significant group × time interaction in throwing velocity (p < 0.001) with the TG posttest results being significantly higher compared with CG (d = 2.1), and also a significant main time effect (p < 0.001), with an increase in throwing velocity of 14% (d = 3.0) and 3.7% (d = 0.3) for both TG and CG, respectively. Throwing precision did not significantly differ between groups and time points. Isokinetic strength measures revealed a significant group × time interaction (p ≤ 0.05) with the TG posttest results being significantly higher compared with CG (d = 0.9) and also a significant main time effect (p < 0.01) with an increase of 15% (d = 0.9) in concentric shoulder internal rotation at 180°·s⁻¹ in the dominant arm in TG, whereas no significant changes occurred in CG. The present results indicate that 6 weeks of MBT elicit significant improvements in functional performance (i.e., throwing velocity) in female handball players, whereas throwing precision remained unaffected. Medicine ball training exercises seem to be a useful and inexpensive strength training strategy in enhancing functional performance by closely mimicking sport-specific movement activities.

Consistency of Field-Based Measures of Neuromuscular Control Using Force-Plate Diagnostics in Elite Male Youth Soccer Players.

PubMed

Read, Paul J; Oliver, Jon L; Croix, Mark Ba De Ste; Myer, Gregory D; Lloyd, Rhodri S

2016-12-01

Read, P, Oliver, JL, Croix, MD, Myer, GD, and Lloyd, RS. Consistency of field-based measures of neuromuscular control using force-plate diagnostics in elite male youth soccer players. J Strength Cond Res 30(12): 3304-3311, 2016-Deficits in neuromuscular control during movement patterns such as landing are suggested pathomechanics that underlie sport-related injury. A common mode of assessment is measurement of landing forces during jumping tasks; however, these measures have been used less frequently in male youth soccer players, and reliability data are sparse. The aim of this study was to examine the reliability of a field-based neuromuscular control screening battery using force-plate diagnostics in this cohort. Twenty-six pre-peak height velocity (PHV) and 25 post-PHV elite male youth soccer players completed a drop vertical jump (DVJ), single-leg 75% horizontal hop and stick (75%HOP), and single-leg countermovement jump (SLCMJ). Measures of peak landing vertical ground reaction force (pVGRF), time to stabilization, time to pVGRF, and pVGRF asymmetry were recorded. A test-retest design was used, and reliability statistics included change in mean, intraclass correlation coefficient, and coefficient of variation (CV). No significant differences in mean score were reported for any of the assessed variables between test sessions. In both groups, pVGRF and asymmetry during the 75%HOP and SLCMJ demonstrated largely acceptable reliability (CV ≤ 10%). Greater variability was evident in DVJ pVGRF and all other assessed variables, across the 3 protocols (CV range = 13.8-49.7%). Intraclass correlation coefficient values ranged from small to large and were generally higher in the post-PHV players. The results of this study suggest that pVGRF and asymmetry can be reliably assessed using a 75%HOP and SLCMJ in this cohort. These measures could be used to support a screening battery for elite male youth soccer players and for test-retest comparison.

A Comparison of Selected Kinematic Factors in Male Baseball and Female Fast Pitch Softball Batting.

ERIC Educational Resources Information Center

Spragg, Carolyn; Noble, Larry

Six female intercollegiate varsity softball players and six male intercollegiate varsity baseball players were filmed from overhead while batting a wiffle ball off a batting tee at hip height. Movements of the hips, trunk, upper body segments, and bat were analyzed. Group comparisons indicated that males had higher peak linear and, angular…

Trust My Face: Cognitive Factors of Head Fakes in Sports

ERIC Educational Resources Information Center

Kunde, Wilfried; Skirde, Stefanie; Weigelt, Matthias

2011-01-01

In many competitive sports, players try to deceive their opponents about their behavioral intentions by using specific body movements or postures called fakes. For example, fakes are performed in basketball when a player gazes in one direction but passes or shoots the ball in another direction to avert efficient defense actions. The present study…

The appropriateness of training exposures for match-play preparation in adolescent schoolboy and academy rugby union players.

PubMed

Phibbs, Padraic J; Jones, Ben; Read, Dale B; Roe, Gregory A B; Darrall-Jones, Joshua; Weakley, Jonathon J S; Rock, Andrew; Till, Kevin

2018-03-01

The aim of this study was to compare the physical and movement demands between training and match-play in schoolboy and academy adolescent rugby union (RU) players. Sixty-one adolescent male RU players (mean ± SD; age 17.0 ± 0.7 years) were recruited from four teams representing school and regional academy standards. Players were categorised into four groups based on playing standard and position: schoolboy forwards (n = 15), schoolboy backs (n = 15), academy forwards (n = 16) and academy backs (n = 15). Global positioning system and accelerometry measures were obtained from training and match-play to assess within-group differences between conditions. Maximum data were analysed from 79 match files across 8 matches (1.3 ± 0.5 matches per participant) and 152 training files across 15 training sessions (2.5 ± 0.5 training sessions per participant). Schoolboy forwards were underprepared for low-intensity activities experienced during match-play, with schoolboy backs underprepared for all movement demands. Academy forwards were exposed to similar physical demands in training to matches, with academy backs similar to or exceeding values for all measured variables. Schoolboy players were underprepared for many key, position-specific aspects of match-play, which could place them at greater risk of injury and hinder performance, unlike academy players who were better prepared.

Influence of field size on the physiological and skill demands of small-sided games in junior and senior rugby league players.

PubMed

Gabbett, Tim J; Abernethy, Bruce; Jenkins, David G

2012-02-01

The purpose of this study was to investigate the effect of changes in field size on the physiological and skill demands of small-sided games in elite junior and senior rugby league players. Sixteen elite senior rugby league players ([mean ± SE] age, 23.6 ± 0.5 years) and 16 elite junior rugby league players ([mean ± SE] age, 17.3 ± 0.3 years) participated in this study. On day 1, 2 teams played an 8-minute small-sided game on a small field (10-m width × 40-m length), whereas the remaining 2 teams played the small-sided game on a larger sized field (40-m width × 70-m length). On day 2, the groups were crossed over. Movement was recorded by a global positioning system unit sampling at 5 Hz. Games were filmed to count the number of possessions and the number and quality of disposals. The games played on a larger field resulted in a greater (p < 0.05) total distance covered, and distances covered in moderate, high, and very-high velocity movement intensities. Senior players covered more distance at moderate, high, and very-high intensities, and less distance at low and very-low intensities during small-sided games than junior players. Although increasing field size had no significant influence (p > 0.05) over the duration of recovery periods for junior players, larger field size significantly reduced (p < 0.05) the amount of short-, moderate-, and long-duration recovery periods in senior players. No significant between-group differences (p > 0.05) were detected for games played on a small or large field for the number or quality of skill involvements. These results suggest that increases in field size serve to increase the physiological demands of small-sided games but have minimal influence over the volume or quality of skill executions in elite rugby league players.

Influence of shoe midsole hardness on plantar pressure distribution in four basketball-related movements.

PubMed

Lam, Wing-Kai; Ng, Wei Xuan; Kong, Pui Wah

2017-01-01

This study examined how shoe midsole hardness influenced plantar pressure in basketball-related movements. Twenty male university basketball players wore customized shoes with hard and soft midsoles (60 and 50 Shore C) to perform four movements: running, maximal forward sprinting, maximal 45° cutting and lay-up. Plantar loading was recorded using an in-shoe pressure measuring system, with peak pressure (PP) and pressure time integral (PTI) extracted from 10 plantar regions. Compared with hard shoes, subjects exhibited lower PP in one or more plantar regions when wearing the soft shoes across all tested movements (Ps < 0.05). Lower PTI was also observed in the hallux for 45° cutting, and the toes and forefoot regions during the first step of lay-up in the soft shoe condition (Ps < 0.05). In conclusion, using a softer midsole in the forefoot region may be a plausible remedy to reduce the high plantar loading experienced by basketball players.

Do pattern recognition skills transfer across sports? A preliminary analysis.

PubMed

Smeeton, Nicholas J; Ward, Paul; Williams, A Mark

2004-02-01

The ability to recognize patterns of play is fundamental to performance in team sports. While typically assumed to be domain-specific, pattern recognition skills may transfer from one sport to another if similarities exist in the perceptual features and their relations and/or the strategies used to encode and retrieve relevant information. A transfer paradigm was employed to compare skilled and less skilled soccer, field hockey and volleyball players' pattern recognition skills. Participants viewed structured and unstructured action sequences from each sport, half of which were randomly represented with clips not previously seen. The task was to identify previously viewed action sequences quickly and accurately. Transfer of pattern recognition skill was dependent on the participant's skill, sport practised, nature of the task and degree of structure. The skilled soccer and hockey players were quicker than the skilled volleyball players at recognizing structured soccer and hockey action sequences. Performance differences were not observed on the structured volleyball trials between the skilled soccer, field hockey and volleyball players. The skilled field hockey and soccer players were able to transfer perceptual information or strategies between their respective sports. The less skilled participants' results were less clear. Implications for domain-specific expertise, transfer and diversity across domains are discussed.

Leadership in moving human groups.

PubMed

Boos, Margarete; Pritz, Johannes; Lange, Simon; Belz, Michael

2014-04-01

How is movement of individuals coordinated as a group? This is a fundamental question of social behaviour, encompassing phenomena such as bird flocking, fish schooling, and the innumerable activities in human groups that require people to synchronise their actions. We have developed an experimental paradigm, the HoneyComb computer-based multi-client game, to empirically investigate human movement coordination and leadership. Using economic games as a model, we set monetary incentives to motivate players on a virtual playfield to reach goals via players' movements. We asked whether (I) humans coordinate their movements when information is limited to an individual group member's observation of adjacent group member motion, (II) whether an informed group minority can lead an uninformed group majority to the minority's goal, and if so, (III) how this minority exerts its influence. We showed that in a human group--on the basis of movement alone--a minority can successfully lead a majority. Minorities lead successfully when (a) their members choose similar initial steps towards their goal field and (b) they are among the first in the whole group to make a move. Using our approach, we empirically demonstrate that the rules of swarming behaviour apply to humans. Even complex human behaviour, such as leadership and directed group movement, follow simple rules that are based on visual perception of local movement.

The influence of shoe drop on the kinematics and kinetics of children tennis players.

PubMed

Herbaut, Alexis; Chavet, Pascale; Roux, Maxime; Guéguen, Nils; Gillet, Christophe; Barbier, Franck; Simoneau-Buessinger, Emilie

2016-11-01

This study investigated the immediate effects of reducing the shoe drop (i.e. the difference between the heel and the forefoot height) on the kinematics and kinetics of the lower extremities of children tennis players performing a tennis-specific movement. Thirteen children tennis players performed a series of simulated open stance forehands wearing 3 pairs of shoes differing only in the drop: 0 (D0), 6 (D6) and the control condition of 12 mm (D12). Two embedded forceplates and a motion capture system were used to analyse the ground reaction forces and ankle and knee joint angles and moments of the leading lower limb. In D6 compared with D12, the peak impact force was reduced by 24% (p = .004) and the ankle was less dorsiflexed at foot strike (p = .037). In D0 compared with D12, the peak impact force was reduced by 17% (p = .049), the ankle was less dorsiflexed at foot strike (p = .045) and the knee was more flexed at foot strike (p = .007). In addition, 4 out of 13 participants (31%) presented a forefoot strike pattern for some of the trials in D0. No difference was observed across shoe conditions for the peak knee extensor moment (p = .658) or the peak ankle plantarflexor moment (p = .071). The results provide preliminary data supporting the hypothesis that for children tennis players, using a 6-mm lower shoe drop might reduce heel impact forces and thus limit potentially impact-related injuries.

Increased Inhibition in Non-Primary Motor Areas of String-Instrument Players: A Preliminary Study with Paired-Pulse Transcranial Magnetic Stimulation

PubMed Central

Vaalto, Selja; Julkunen, Petro; Säïsänen, Laura; Könönen, Mervi; Määttä, Sara; Karhu, Jari

2016-01-01

Background: The muscle representations in non-primary motor area (NPMA) are located in the dorsal premotor area (PMd) and in the border region between the premotor area and the supplementary motor area (SMA). Objective: We characterized the plasticity of intracortical inhibitory and excitatory circuits in muscle representations in primary motor cortex (M1) and in NPMA related to acquired fine motor skills. We compared local cortical inhibition and facilitation balance in M1 and in NPMA between control subjects (n = 6) and right-handed string-instrument players (n = 5). Methods: Navigated transcranial magnetic stimulation (TMS) was used to compare motor thresholds (MTs), motor evoked potentials (MEPs), short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF) in non-dominant hand muscle representations in M1 and NPMA. Results: String-instrument players showed reduced SICI in M1 in the actively used left hand abductor digiti minimi (ADM) muscle representation at 3 ms inter-stimulus interval (ISI) with a conditioning stimulus (CS) intensity of 80% of MT and increased SICI in NPMA in ADM representation at 2 ms ISI and CS intensity of 50% of MT in comparison with controls. No differences between string-instrument players and controls were found for the SICI in the left hand opponens pollicis (OP) muscle representation, which is a muscle not intensively trained in string-instrument players. Conclusions: These preliminary results indicate that the stronger inhibition in motor representations outside M1 in string-instrument players may be crucial when accurate movements of single muscles must be performed. In contrast, weaker inhibition in M1 in string-instrument players may benefit the performance of fast finger movements. PMID:29765844

Stimulus- and goal-driven control of eye movements: action videogame players are faster but not better.

PubMed

Heimler, Benedetta; Pavani, Francesco; Donk, Mieke; van Zoest, Wieske

2014-11-01

Action videogame players (AVGPs) have been shown to outperform nongamers (NVGPs) in covert visual attention tasks. These advantages have been attributed to improved top-down control in this population. The time course of visual selection, which permits researchers to highlight when top-down strategies start to control performance, has rarely been investigated in AVGPs. Here, we addressed specifically this issue through an oculomotor additional-singleton paradigm. Participants were instructed to make a saccadic eye movement to a unique orientation singleton. The target was presented among homogeneous nontargets and one additional orientation singleton that was more, equally, or less salient than the target. Saliency was manipulated in the color dimension. Our results showed similar patterns of performance for both AVGPs and NVGPs: Fast-initiated saccades were saliency-driven, whereas later-initiated saccades were more goal-driven. However, although AVGPs were faster than NVGPs, they were also less accurate. Importantly, a multinomial model applied to the data revealed comparable underlying saliency-driven and goal-driven functions for the two groups. Taken together, the observed differences in performance are compatible with the presence of a lower decision bound for releasing saccades in AVGPs than in NVGPs, in the context of comparable temporal interplay between the underlying attentional mechanisms. In sum, the present findings show that in both AVGPs and NVGPs, the implementation of top-down control in visual selection takes time to come about, and they argue against the idea of a general enhancement of top-down control in AVGPs.

Efficiently detecting outlying behavior in video-game players.

PubMed

Kim, Young Bin; Kang, Shin Jin; Lee, Sang Hyeok; Jung, Jang Young; Kam, Hyeong Ryeol; Lee, Jung; Kim, Young Sun; Lee, Joonsoo; Kim, Chang Hun

2015-01-01

In this paper, we propose a method for automatically detecting the times during which game players exhibit specific behavior, such as when players commonly show excitement, concentration, immersion, and surprise. The proposed method detects such outlying behavior based on the game players' characteristics. These characteristics are captured non-invasively in a general game environment. In this paper, cameras were used to analyze observed data such as facial expressions and player movements. Moreover, multimodal data from the game players (i.e., data regarding adjustments to the volume and the use of the keyboard and mouse) was used to analyze high-dimensional game-player data. A support vector machine was used to efficiently detect outlying behaviors. We verified the effectiveness of the proposed method using games from several genres. The recall rate of the outlying behavior pre-identified by industry experts was approximately 70%. The proposed method can also be used for feedback analysis of various interactive content provided in PC environments.

The influence of tennis court surfaces on player perceptions and biomechanical response.

PubMed

Starbuck, Chelsea; Damm, Loïc; Clarke, James; Carré, Matt; Capel-Davis, Jamie; Miller, Stuart; Stiles, Victoria; Dixon, Sharon

2016-09-01

This study aimed to examine player perceptions and biomechanical responses to tennis surfaces and to evaluate the influence of prior clay court experience. Two groups with different clay experiences (experience group, n = 5 and low-experience group, n = 5) performed a 180° turning movement. Three-dimensional ankle and knee movements (50 Hz), plantar pressure of the turning step (100 Hz) and perception data (visual analogue scale questionnaire) were collected for two tennis courts (acrylic and clay). Greater initial knee flexion (acrylic 20. 8 ± 11.2° and clay 32.5 ± 9.4°) and a more upright position were reported on the clay compared to the acrylic court (P < 0.05). This suggests adaptations to increase player stability on clay. Greater hallux pressures and lower midfoot pressures were observed on the clay court, allowing for sliding whilst providing grip at the forefoot. Players with prior clay court experience exhibited later peak knee flexion compared to those with low experience. All participants perceived the differences in surface properties between courts and thus responded appropriately to these differences. The level of previous clay court experience did not influence players' perceptions of the surfaces; however, those with greater clay court experience may reduce injury risk as a result of reduced loading through later peak knee flexion.

From eye movements to actions: how batsmen hit the ball.

PubMed

Land, M F; McLeod, P

2000-12-01

In cricket, a batsman watches a fast bowler's ball come toward him at a high and unpredictable speed, bouncing off ground of uncertain hardness. Although he views the trajectory for little more than half a second, he can accurately judge where and when the ball will reach him. Batsmen's eye movements monitor the moment when the ball is released, make a predictive saccade to the place where they expect it to hit the ground, wait for it to bounce, and follow its trajectory for 100-200 ms after the bounce. We show how information provided by these fixations may allow precise prediction of the ball's timing and placement. Comparing players with different skill levels, we found that a short latency for the first saccade distinguished good from poor batsmen, and that a cricket player's eye movement strategy contributes to his skill in the game.

Effect of contact and no-contact small-sided games on elite handball players.

PubMed

Dello Iacono, Antonio; Martone, Domenico; Zagatto, Alessandro Moura; Meckel, Yoav; Sindiani, Mahmood; Milic, Mirjana; Padulo, Johnny

2018-01-01

This study aimed to investigate the effect of contact (C-SSG) and no-contact (NC-SSG) handball small-sided games (SSGs) on motion patterns and physiological responses of elite handball players. Twelve male handball players performed 10 C-SSG and 10 NC-SSG while being monitored through the heart rate (HR) and rate of perceived exertion (RPE) as physiological responses and time-motion activities profile using video-match analysis. Both game conditions resulted in similar HR responses (P > 0.05), but the NC-SSG led to a higher RPE scores. The time-motion activity analysis featured NC-SSG with a greater amount of walking (855.6 ± 25.1 vs. 690.6 ± 35.2 m) and backward movements (187.5 ± 12.3 vs. 142.5 ± 8.7 m) combined with fast running (232.3 ± 8.5 vs. 159.7 ± 5.7 m) and sprinting (79.5 ± 4.7 vs. 39.7 ± 3.7 m) activities (P < 0.001). Conversely, C-SSG had a higher percentage of jogging and sideway movements associated with greater frequency of jumping (0.87 ± 0.09 vs. 0.31 ± 0.06 nr) and physical contact (1.82 ± 0.55 vs. 0.25 ± 0.03 nr) events (P < 0.001). No between-regimen differences were found for the number of throws (P = 0.745). In addition, the RPE was significantly correlated with fast running relative distances (r = 0.909, P < 0.001) and sprinting relative distances (r = 0.939, P < 0.001). In conclusion, this investigation showed that both C-SSG and NC-SSG in team handball can effectively represent specifically oriented exercises, according to the sport-task and the performance demands.

Increased Complexities in Visual Search Behavior in Skilled Players for a Self-Paced Aiming Task

PubMed Central

Chia, Jingyi S.; Burns, Stephen F.; Barrett, Laura A.; Chow, Jia Y.

2017-01-01

The badminton serve is an important shot for winning a rally in a match. It combines good technique with the ability to accurately integrate visual information from the shuttle, racket, opponent, and intended landing point. Despite its importance and repercussive nature, to date no study has looked at the visual search behaviors during badminton service in the singles discipline. Unlike anticipatory tasks (e.g., shot returns), the serve presents an opportunity to explore the role of visual search behaviors in movement control for self-paced tasks. Accordingly, this study examined skill-related differences in visual behavior during the badminton singles serve. Skilled (n = 12) and less skilled (n = 12) participants performed 30 serves to a live opponent, while real-time eye movements were captured using a mobile gaze registration system. Frame-by-frame analyses of 662 serves were made and the skilled players took a longer preparatory time before serving. Visual behavior of the skilled players was characterized by significantly greater number of fixations on more areas of interest per trial than the less skilled. In addition, the skilled players spent a significantly longer time fixating on the court and net, whereas the less skilled players found the shuttle to be more informative. Quiet eye (QE) duration (indicative of superior sports performance) however, did not differ significantly between groups which has implications on the perceived importance of QE in the badminton serve. Moreover, while visual behavior differed by skill level, considerable individual differences were also observed especially within the skilled players. This augments the need for not just group-level analyses, but individualized analysis for a more accurate representation of visual behavior. Findings from this study thus provide an insight to the possible visual search strategies as players serve in net-barrier games. Moreover, this study highlighted an important aspect of badminton relating to deception and the implications of interpreting visual behavior of players. PMID:28659850

Increased Complexities in Visual Search Behavior in Skilled Players for a Self-Paced Aiming Task.

PubMed

Chia, Jingyi S; Burns, Stephen F; Barrett, Laura A; Chow, Jia Y

2017-01-01

The badminton serve is an important shot for winning a rally in a match. It combines good technique with the ability to accurately integrate visual information from the shuttle, racket, opponent, and intended landing point. Despite its importance and repercussive nature, to date no study has looked at the visual search behaviors during badminton service in the singles discipline. Unlike anticipatory tasks (e.g., shot returns), the serve presents an opportunity to explore the role of visual search behaviors in movement control for self-paced tasks. Accordingly, this study examined skill-related differences in visual behavior during the badminton singles serve. Skilled ( n = 12) and less skilled ( n = 12) participants performed 30 serves to a live opponent, while real-time eye movements were captured using a mobile gaze registration system. Frame-by-frame analyses of 662 serves were made and the skilled players took a longer preparatory time before serving. Visual behavior of the skilled players was characterized by significantly greater number of fixations on more areas of interest per trial than the less skilled. In addition, the skilled players spent a significantly longer time fixating on the court and net, whereas the less skilled players found the shuttle to be more informative. Quiet eye (QE) duration (indicative of superior sports performance) however, did not differ significantly between groups which has implications on the perceived importance of QE in the badminton serve. Moreover, while visual behavior differed by skill level, considerable individual differences were also observed especially within the skilled players. This augments the need for not just group-level analyses, but individualized analysis for a more accurate representation of visual behavior. Findings from this study thus provide an insight to the possible visual search strategies as players serve in net-barrier games. Moreover, this study highlighted an important aspect of badminton relating to deception and the implications of interpreting visual behavior of players.

Neuromuscular Risk Factors for Knee and Ankle Ligament Injuries in Male Youth Soccer Players.

PubMed

Read, Paul J; Oliver, Jon L; De Ste Croix, Mark B A; Myer, Gregory D; Lloyd, Rhodri S

2016-08-01

Injuries reported in male youth soccer players most commonly occur in the lower extremities, and include a high proportion of ligament sprains at the ankle and knee with a lower proportion of overuse injuries. There is currently a paucity of available literature that examines age- and sex-specific injury risk factors for such injuries within youth soccer players. Epidemiological data have reported movements that lead to non-contact ligament injury include running, twisting and turning, over-reaching and landing. Altered neuromuscular control during these actions has been suggested as a key mechanism in females and adult populations; however, data available in male soccer players is sparse. The focus of this article is to review the available literature and elucidate prevalent risk factors pertaining to male youth soccer players which may contribute to their relative risk of injury.

Locomotion characteristics and match-induced impairments in physical performance in male elite team handball players.

PubMed

Michalsik, L B; Aagaard, P; Madsen, K

2013-07-01

The purpose of this study was to determine the physical demands and match-induced impairments in physical performance in male elite Team Handball (TH) players in relation to playing position. Male elite TH field players were closely observed during 6 competitive seasons. Each player (wing players: WP, pivots: PV, backcourt players: BP) was evaluated during match-play using video recording and subsequently performing locomotion match analysis. A total distance of 3 627±568 m (group means±SD) was covered per match with a total effective playing time (TPT) of 53:51±5:52 min:s, while full-time players covered 3 945±538 m. The mean speed was 6.40±1.01 km · h - 1. High-intensity running constituted only 1.7±0.9% of TPT per match corresponding to 7.9±4.9% of the total distance covered. An average of 1 482.4±312.6 activity changes per player (n=82) with 53.2±14.1 high-intensity runs were observed per match. Total distance covered was greater in BP (3 765±532 m) and WP (3 641±501 m) than PV (3 295±495 m) (p<0.05), and WP performed more high-intensity running (10.9±5.7% of total distance covered) than PV (8.5±4.3%, p<0.05) and BP (6.2±3.2%, p<0.01). The amount of high-intensity running was lower (p<0.05) in the second (130.4±38.4 m) than in the first half (155.3±47.6 m) corresponding to a decrease of 16.2%.In conclusion, modern male elite TH is a complex team sport that comprises several types of movement categories, which during match-play place moderate-to-high demands on intermittent endurance running capacity and where the amount of high-intensity running may be high during brief periods of the match. Signs of fatigue-related changes were observed in terms of temporary impaired physical performance, since the amount of high-intensity running was reduced in the second half. Notably, physical demands differed between playing positions, with WP demonstrating a more intensive activity pattern than BP and PV, respectively. © Georg Thieme Verlag KG Stuttgart · New York.

Enhancing the control of force in putting by video game training.

PubMed

Fery, Y A; Ponserre, S

2001-10-10

Even if golf video games provide no proprioceptive afferences on actual putting movement, they may give sufficient substitutive visual cues to enhance force control in this skill. It was hypothesized that this usefulness requires, however, two conditions: the video game must provide reliable demonstrations of actual putts, and the user must want to use the game to make progress in actual putting. Accordingly, a video game was selected on the basis of its fidelity to the real-world game. It allowed two different methods of adjusting the virtual player's putting force in order to hole a putt: an analogue method that consisted of focusing on the virtual player's movement and a symbolic method that consisted of focusing on the movement of a gauge on a scale representing the virtual player's putting force. The participants had to use one of these methods with either the intention of making progress in actual putting or in a second condition to simply enjoy the game. Results showed a positive transfer of video playing to actual putting skill for the learning group and also, to a lesser degree, for the enjoyment group; but only when they used the symbolic method. Results are discussed in the context of how vision may convey force cues in sports video games.

Bring It to the Pitch: Combining Video and Movement Data to Enhance Team Sport Analysis.

PubMed

Stein, Manuel; Janetzko, Halldor; Lamprecht, Andreas; Breitkreutz, Thorsten; Zimmermann, Philipp; Goldlucke, Bastian; Schreck, Tobias; Andrienko, Gennady; Grossniklaus, Michael; Keim, Daniel A

2018-01-01

Analysts in professional team sport regularly perform analysis to gain strategic and tactical insights into player and team behavior. Goals of team sport analysis regularly include identification of weaknesses of opposing teams, or assessing performance and improvement potential of a coached team. Current analysis workflows are typically based on the analysis of team videos. Also, analysts can rely on techniques from Information Visualization, to depict e.g., player or ball trajectories. However, video analysis is typically a time-consuming process, where the analyst needs to memorize and annotate scenes. In contrast, visualization typically relies on an abstract data model, often using abstract visual mappings, and is not directly linked to the observed movement context anymore. We propose a visual analytics system that tightly integrates team sport video recordings with abstract visualization of underlying trajectory data. We apply appropriate computer vision techniques to extract trajectory data from video input. Furthermore, we apply advanced trajectory and movement analysis techniques to derive relevant team sport analytic measures for region, event and player analysis in the case of soccer analysis. Our system seamlessly integrates video and visualization modalities, enabling analysts to draw on the advantages of both analysis forms. Several expert studies conducted with team sport analysts indicate the effectiveness of our integrated approach.

Biomotor structures in elite female handball players.

PubMed

Katić, Ratko; Cavala, Marijana; Srhoj, Vatromir

2007-09-01

In order to identify biomotor structures in elite female handball players, factor structures of morphological characteristics and basic motor abilities of elite female handball players (N = 53) were determined first, followed by determination of relations between the morphological-motor space factors obtained and the set of criterion variables evaluating situation motor abilities in handball. Factor analysis of 14 morphological measures produced three morphological factors, i.e. factor of absolute voluminosity (mesoendomorph), factor of longitudinal skeleton dimensionality, and factor of transverse hand dimensionality. Factor analysis of 15 motor variables yielded five basic motor dimensions, i.e. factor of agility, factor of jumping explosive strength, factor of throwing explosive strength, factor of movement frequency rate, and factor of running explosive strength (sprint). Four significant canonic correlations, i.e. linear combinations, explained the correlation between the set of eight latent variables of the morphological and basic motor space and five variables of situation motoricity. First canonic linear combination is based on the positive effect of the factors of agility/coordination on the ability of fast movement without ball. Second linear combination is based on the effect of jumping explosive strength and transverse hand dimensionality on ball manipulation, throw precision, and speed of movement with ball. Third linear combination is based on the running explosive strength determination by the speed of movement with ball, whereas fourth combination is determined by throwing and jumping explosive strength, and agility on ball pass. The results obtained were consistent with the model of selection in female handball proposed (Srhoj et al., 2006), showing the speed of movement without ball and the ability of ball manipulation to be the predominant specific abilities, as indicated by the first and second linear combination.

Haptic perception accuracy depending on self-produced movement.

PubMed

Park, Chulwook; Kim, Seonjin

2014-01-01

This study measured whether self-produced movement influences haptic perception ability (experiment 1) as well as the factors associated with levels of influence (experiment 2) in racket sports. For experiment 1, the haptic perception accuracy levels of five male table tennis experts and five male novices were examined under two different conditions (no movement vs. movement). For experiment 2, the haptic afferent subsystems of five male table tennis experts and five male novices were investigated in only the self-produced movement-coupled condition. Inferential statistics (ANOVA, t-test) and custom-made devices (shock & vibration sensor, Qualisys Track Manager) of the data were used to determine the haptic perception accuracy (experiment 1, experiment 2) and its association with expertise. The results of this research show that expert-level players acquire higher accuracy with less variability (racket vibration and angle) than novice-level players, especially in their self-produced movement coupled performances. The important finding from this result is that, in terms of accuracy, the skill-associated differences were enlarged during self-produced movement. To explain the origin of this difference between experts and novices, the functional variability of haptic afferent subsystems can serve as a reference. These two factors (self-produced accuracy and the variability of haptic features) as investigated in this study would be useful criteria for educators in racket sports and suggest a broader hypothesis for further research into the effects of the haptic accuracy related to variability.

Identifying the Physical Fitness, Anthropometric and Athletic Movement Qualities Discriminant of Developmental Level in Elite Junior Australian Football: Implications for the Development of Talent.

PubMed

Gaudion, Sarah L; Doma, Kenji; Sinclair, Wade; Banyard, Harry G; Woods, Carl T

2017-07-01

Gaudion, SL, Doma, K, Sinclair, W, Banyard, HG, and Woods, CT. Identifying the physical fitness, anthropometric and athletic movement qualities discriminant of developmental level in elite junior Australian football: implications for the development of talent. J Strength Cond Res 31(7): 1830-1839, 2017-This study aimed to identify the physical fitness, anthropometric and athletic movement qualities discriminant of developmental level in elite junior Australian football (AF). From a total of 77 players, 2 groups were defined according to their developmental level; under 16 (U16) (n = 40, 15.6 to 15.9 years), and U18 (n = 37, 17.1 to 17.9 years). Players performed a test battery consisting of 7 physical fitness assessments, 2 anthropometric measurements, and a fundamental athletic movement assessment. A multivariate analysis of variance tested the main effect of developmental level (2 levels: U16 and U18) on the assessment criterions, whilst binary logistic regression models and receiver operating characteristic (ROC) curves were built to identify the qualities most discriminant of developmental level. A significant effect of developmental level was evident on 9 of the assessments (d = 0.27-0.88; p ≤ 0.05). However, it was a combination of body mass, dynamic vertical jump height (nondominant leg), repeat sprint time, and the score on the 20-m multistage fitness test that provided the greatest association with developmental level (Akaike's information criterion = 80.84). The ROC curve was maximized with a combined score of 180.7, successfully discriminating 89 and 60% of the U18 and U16 players, respectively (area under the curve = 79.3%). These results indicate that there are distinctive physical fitness and anthropometric qualities discriminant of developmental level within the junior AF talent pathway. Coaches should consider these differences when designing training interventions at the U16 level to assist with the development of prospective U18 AF players.

Design of a Virtual Player for Joint Improvisation with Humans in the Mirror Game

PubMed Central

Zhai, Chao; Alderisio, Francesco; Tsaneva-Atanasova, Krasimira; di Bernardo, Mario

2016-01-01

Joint improvisation is often observed among humans performing joint action tasks. Exploring the underlying cognitive and neural mechanisms behind the emergence of joint improvisation is an open research challenge. This paper investigates jointly improvised movements between two participants in the mirror game, a paradigmatic joint task example. First, experiments involving movement coordination of different dyads of human players are performed in order to build a human benchmark. No designation of leader and follower is given beforehand. We find that joint improvisation is characterized by the lack of a leader and high levels of movement synchronization. Then, a theoretical model is proposed to capture some features of their interaction, and a set of experiments is carried out to test and validate the model ability to reproduce the experimental observations. Furthermore, the model is used to drive a computer avatar able to successfully improvise joint motion with a human participant in real time. Finally, a convergence analysis of the proposed model is carried out to confirm its ability to reproduce joint movements between the participants. PMID:27123927

Design of a Virtual Player for Joint Improvisation with Humans in the Mirror Game.

PubMed

Zhai, Chao; Alderisio, Francesco; Słowiński, Piotr; Tsaneva-Atanasova, Krasimira; di Bernardo, Mario

2016-01-01

Joint improvisation is often observed among humans performing joint action tasks. Exploring the underlying cognitive and neural mechanisms behind the emergence of joint improvisation is an open research challenge. This paper investigates jointly improvised movements between two participants in the mirror game, a paradigmatic joint task example. First, experiments involving movement coordination of different dyads of human players are performed in order to build a human benchmark. No designation of leader and follower is given beforehand. We find that joint improvisation is characterized by the lack of a leader and high levels of movement synchronization. Then, a theoretical model is proposed to capture some features of their interaction, and a set of experiments is carried out to test and validate the model ability to reproduce the experimental observations. Furthermore, the model is used to drive a computer avatar able to successfully improvise joint motion with a human participant in real time. Finally, a convergence analysis of the proposed model is carried out to confirm its ability to reproduce joint movements between the participants.

Strength Determinants of Jump Height in the Jump Throw Movement in Women Handball Players.

PubMed

McGhie, David; Østerås, Sindre; Ettema, Gertjan; Paulsen, Gøran; Sandbakk, Øyvind

2018-06-08

McGhie, D, Østerås, S, Ettema, G, Paulsen, G, and Sandbakk, Ø. Strength determinants of jump height in the jump throw movement in women handball players. J Strength Cond Res XX(X): 000-000, 2018-The purpose of the study was to improve the understanding of the strength demands of a handball-specific jump through examining the associations between jump height in a jump throw jump (JTJ) and measures of lower-body maximum strength and impulse in handball players. For comparison, whether the associations between jump height and strength differed between the JTJ and the customarily used countermovement jump (CMJ) was also examined. Twenty women handball players from a Norwegian top division club participated in the study. Jump height was measured in the JTJ and in unilateral and bilateral CMJ. Lower-body strength (maximum isometric force, one-repetition maximum [1RM], impulse at ∼60% and ∼35% 1RM) was measured in seated leg press. The associations between jump height and strength were assessed with correlation analyses and t-tests of dependent r's were performed to determine if correlations differed between jump tests. Only impulse at ∼35% 1RM correlated significantly with JTJ height (p < 0.05), whereas all strength measures correlated significantly with CMJ heights (p < 0.001). The associations between jump height and strength were significantly weaker in the JTJ than in both CMJ tests for all strength measures (p = 0.001-0.044) except one. Maximum strength and impulse at ∼60% 1RM did not seem to sufficiently capture the capabilities associated with JTJ height, highlighting the importance of employing tests targeting performance-relevant neuromuscular characteristics when assessing jump-related strength in handball players. Further, CMJ height seemed to represent a wider range of strength capabilities and care should be taken when using it as a proxy for handball-specific movements.

Reducing musculoskeletal injury and concussion risk in schoolboy rugby players with a pre-activity movement control exercise programme: a cluster randomised controlled trial

PubMed Central

Hislop, Michael D; Stokes, Keith A; Williams, Sean; McKay, Carly D; England, Mike E; Kemp, Simon P T; Trewartha, Grant

2017-01-01

Background Injury risk in youth rugby has received much attention, highlighting the importance of establishing evidence-based injury reduction strategies. Aim To determine the efficacy of a movement control exercise programme in reducing injuries in youth rugby players and to investigate the effect of programme dose on injury measures. Methods In a cluster-randomised controlled trial, 40 independent schools (118 teams, 3188 players aged 14–18 years) were allocated to receive either the intervention or a reference programme, both of which were to be delivered by school coaches. The intervention comprised balance training, whole-body resistance training, plyometric training, and controlled rehearsal of landing and cutting manoeuvres. Time-loss (>24 hours) injuries arising from school rugby matches were recorded by coaches and medical staff. Results 441 time-loss match injuries (intervention, 233; control, 208) were reported across 15 938 match exposure-hours (intervention, 9083; control, 6855). Intention-to-treat results indicated unclear effects of trial arm on overall match injury incidence (rate ratio (RR)=0.85, 90% confidence limits 0.61 to 1.17), although clear reductions were evident in the intervention arm for concussion incidence (RR=0.71, 0.48 to 1.05). When trial arm comparisons were limited to teams who had completed three or more weekly programme sessions on average, clear reductions in overall match injury incidence (RR=0.28, 0.14 to 0.51) and concussion incidence (RR=0.41, 0.17 to 0.99) were noted in the intervention group. Conclusion A preventive movement control exercise programme can reduce match injury outcomes, including concussion, in schoolboy rugby players when compared with a standardised control exercise programme, although to realise the greatest effects players should complete the programme at least three times per week. PMID:28515056

Reducing musculoskeletal injury and concussion risk in schoolboy rugby players with a pre-activity movement control exercise programme: a cluster randomised controlled trial.

PubMed

Hislop, Michael D; Stokes, Keith A; Williams, Sean; McKay, Carly D; England, Mike E; Kemp, Simon P T; Trewartha, Grant

2017-08-01

Injury risk in youth rugby has received much attention, highlighting the importance of establishing evidence-based injury reduction strategies. To determine the efficacy of a movement control exercise programme in reducing injuries in youth rugby players and to investigate the effect of programme dose on injury measures. In a cluster-randomised controlled trial, 40 independent schools (118 teams, 3188 players aged 14-18 years) were allocated to receive either the intervention or a reference programme, both of which were to be delivered by school coaches. The intervention comprised balance training, whole-body resistance training, plyometric training, and controlled rehearsal of landing and cutting manoeuvres. Time-loss (>24 hours) injuries arising from school rugby matches were recorded by coaches and medical staff. 441 time-loss match injuries (intervention, 233; control, 208) were reported across 15 938 match exposure-hours (intervention, 9083; control, 6855). Intention-to-treat results indicated unclear effects of trial arm on overall match injury incidence (rate ratio (RR)=0.85, 90% confidence limits 0.61 to 1.17), although clear reductions were evident in the intervention arm for concussion incidence (RR=0.71, 0.48 to 1.05). When trial arm comparisons were limited to teams who had completed three or more weekly programme sessions on average, clear reductions in overall match injury incidence (RR=0.28, 0.14 to 0.51) and concussion incidence (RR=0.41, 0.17 to 0.99) were noted in the intervention group. A preventive movement control exercise programme can reduce match injury outcomes, including concussion, in schoolboy rugby players when compared with a standardised control exercise programme, although to realise the greatest effects players should complete the programme at least three times per week. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Physiological and psychophysiological responses to an exer-game training protocol.

PubMed

Bronner, Shaw; Pinsker, Russell; Naik, Rutika; Noah, J Adam

2016-03-01

Exer-games and virtual reality offer alternative opportunities to provide neuro-rehabilitation and exercise that are fun. Our goal was to determine how effective they are in achieving motor learning goals and fitness benefits as players gain experience. We employed a repeated measures design to determine changes in physical exertion and engagement with training. Fourteen healthy adults trained on the XBOX Kinect video game Dance Central using a skill-based protocol to examine changes in energy expenditure (EE), heart rate (HR), METs, limb movement, game proficiency, and player engagement in initial, post-training, and transfer-testing of a full-body dance exer-game. Data were analyzed using repeated measures analysis of variance, p<0.05. Both EE, HR, and METs increased from initial (EE 4.89±1.35, HR 103±18, METs 4.25±0.72) to post-training (EE 5.92±1.25, HR 110±15, METs 5.05±0.75) and were greatest during transfer-testing (EE 6.34±1.35, HR 115±17, METs 5.42±0.88, p≤0.001). Proficiency, measured by game scores, also increased from initial to post-training and transfer-testing (p≤0.002). Limb movement and player engagement remained unchanged. It is important to understand whether player physiological and psychophysiological responses change with continued game-play. Although Dance Central involves whole-body movement, physical exertion remained at moderate levels after training. As exer-game and virtual reality systems move from their initial novelty, research about how players react to continued involvement with a game can guide game developers to maintain a freshness through game progression that preserves the participant's attentional focus, minimizes attrition and maintains a prescribed level of energy exertion. Copyright © 2015 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Training Patterns of Wheelchair Basketball Players in Turkey

ERIC Educational Resources Information Center

Tatar, Yasar

2008-01-01

The aim of this study was to analyze technical drills, warm-up and cool-down exercises used by wheelchair basketball players of the Turkish league in relation to training sessions. 33 male wheelchair basketball players participated in the study (mean age 26.6[plus or minus]5,95 years). All players reported that they used warm-up exercises before…

Motivations for play in online games.

PubMed

Yee, Nick

2006-12-01

An empirical model of player motivations in online games provides the foundation to understand and assess how players differ from one another and how motivations of play relate to age, gender, usage patterns, and in-game behaviors. In the current study, a factor analytic approach was used to create an empirical model of player motivations. The analysis revealed 10 motivation subcomponents that grouped into three overarching components (achievement, social, and immersion). Relationships between motivations and demographic variables (age, gender, and usage patterns) are also presented.

Efficiently detecting outlying behavior in video-game players

PubMed Central

Kim, Young Bin; Kang, Shin Jin; Lee, Sang Hyeok; Jung, Jang Young; Kam, Hyeong Ryeol; Lee, Jung; Kim, Young Sun; Lee, Joonsoo

2015-01-01

In this paper, we propose a method for automatically detecting the times during which game players exhibit specific behavior, such as when players commonly show excitement, concentration, immersion, and surprise. The proposed method detects such outlying behavior based on the game players’ characteristics. These characteristics are captured non-invasively in a general game environment. In this paper, cameras were used to analyze observed data such as facial expressions and player movements. Moreover, multimodal data from the game players (i.e., data regarding adjustments to the volume and the use of the keyboard and mouse) was used to analyze high-dimensional game-player data. A support vector machine was used to efficiently detect outlying behaviors. We verified the effectiveness of the proposed method using games from several genres. The recall rate of the outlying behavior pre-identified by industry experts was approximately 70%. The proposed method can also be used for feedback analysis of various interactive content provided in PC environments. PMID:26713250

Position-Dependent Cardiovascular Response and Time-Motion Analysis During Training Drills and Friendly Matches in Elite Male Basketball Players.

PubMed

Torres-Ronda, Lorena; Ric, Angel; Llabres-Torres, Ivan; de Las Heras, Bernat; Schelling I Del Alcazar, Xavi

2016-01-01

The purpose of this study was to measure differences in the cardiovascular workload (heart rate [HR]) and time-motion demands between positional groups, during numerous basketball training drills, and compare the results with in-game competition demands. A convenience sample of 14 top-level professional basketball players from the same club (Spanish First Division, ACB) participated in the study. A total of 146 basketball exercises per player (performed over an 8-week period in 32 team training sessions throughout the competitive season) and 7 friendly matches (FM) played during the preparatory phase were analyzed. The results reveal that HRavg and HRpeak were the highest in FM (158 ± 10; 198 ± 9 b · min(-1), respectively). Time-motion analysis showed 1v1 to be the most demanding drill (53 ± 8 and 46 ± 12 movements per minute for full and half court, respectively). During FM, players performed 33 ± 7 movements per minute. Positional differences exist for both HR and time-motion demands, ranging from moderate to very large for all basketball drills compared with FM. Constraints such as number of players, court size, work-to-rest ratios, and coach intervention are key factors influencing cardiovascular responses and time-motion demands during basketball training sessions. These results demonstrate that systematic monitoring of the physical demands and physiological responses during training and competition can inform and potentially improve coaching strategy, basketball-specific training drills, and ultimately, match performance.

Planning abilities and chess: a comparison of chess and non-chess players on the Tower of London task.

PubMed

Unterrainer, J M; Kaller, C P; Halsband, U; Rahm, B

2006-08-01

Playing chess requires problem-solving capacities in order to search through the chess problem space in an effective manner. Chess should thus require planning abilities for calculating many moves ahead. Therefore, we asked whether chess players are better problem solvers than non-chess players in a complex planning task. We compared planning performance between chess ( N=25) and non-chess players ( N=25) using a standard psychometric planning task, the Tower of London (ToL) test. We also assessed fluid intelligence (Raven Test), as well as verbal and visuospatial working memory. As expected, chess players showed better planning performance than non-chess players, an effect most strongly expressed in difficult problems. On the other hand, they showed longer planning and movement execution times, especially for incorrectly solved trials. No differences in fluid intelligence and verbal/visuospatial working memory were found between both groups. These findings indicate that better performance in chess players is associated with disproportionally longer solution times, although it remains to be investigated whether motivational or strategic differences account for this result.

The Effect of Biological Movement Variability on the Performance of the Golf Swing in High- and Low-Handicapped Players

ERIC Educational Resources Information Center

Bradshaw, Elizabeth J.; Keogh, Justin W. L.; Hume, Patria A.; Maulder, Peter S.; Nortje, Jacques; Marnewick, Michel

2009-01-01

The purpose of this study was to examine the role of neuromotor noise on golf swing performance in high- and low-handicap players. Selected two-dimensional kinematic measures of 20 male golfers (n = 10 per high- or low-handicap group) performing 10 golf swings with a 5-iron club was obtained through video analysis. Neuromotor noise was calculated…

A previous hamstring injury affects kicking mechanics in soccer players.

PubMed

Navandar, Archit; Veiga, Santiago; Torres, Gonzalo; Chorro, David; Navarro, Enrique

2018-01-10

Although the kicking skill is influenced by limb dominance and sex, how a previous hamstring injury affects kicking has not been studied in detail. Thus, the objective of this study was to evaluate the effect of sex and limb dominance on kicking in limbs with and without a previous hamstring injury. 45 professional players (males: n=19, previously injured players=4, age=21.16 ± 2.00 years; females: n=19, previously injured players=10, age=22.15 ± 4.50 years) performed 5 kicks each with their preferred and non-preferred limb at a target 7m away, which were recorded with a three-dimensional motion capture system. Kinematic and kinetic variables were extracted for the backswing, leg cocking, leg acceleration and follow through phases. A shorter backswing (20.20 ± 3.49% vs 25.64 ± 4.57%), and differences in knee flexion angle (58 ± 10o vs 72 ± 14o) and hip flexion velocity (8 ± 0rad/s vs 10 ± 2rad/s) were observed in previously injured, non-preferred limb kicks for females. A lower peak hip linear velocity (3.50 ± 0.84m/s vs 4.10 ± 0.45m/s) was observed in previously injured, preferred limb kicks of females. These differences occurred in the backswing and leg-cocking phases where the hamstring muscles were the most active. A variation in the functioning of the hamstring muscles and that of the gluteus maximus and iliopsoas in the case of a previous injury could account for the differences observed in the kicking pattern. Therefore, the effects of a previous hamstring injury must be considered while designing rehabilitation programs to re-educate kicking movement.

Somatotype-variables related to muscle torque and power output in female volleyball players.

PubMed

Buśko, Krzysztof; Lewandowska, Joanna; Lipińska, Monika; Michalski, Radosław; Pastuszak, Anna

2013-01-01

The purpose of this study was to investigate the relationship between somatotype, muscle torque, maximal power output and height of rise of the body mass centre measured in akimbo counter movement jump (ACMJ), counter movement jump (CMJ) and spike jump (SPJ), and power output measured in maximal cycle ergometer exercise bouts in female volleyball players. Fourteen players participated in the study. Somatotype was determined using the Heath-Carter method. Maximal muscle torque was measured under static conditions. Power output was measured in 5 maximal cycle ergometer exercise bouts, 10 s each, at increasing external loads equal to 2.5, 5.0, 7.5, 10.0 and 12.5% of body weight (BW). All jump trials (ACMJ, SPJ and CMJ) were performed on a force plate. The mean somatotype of volleyball players was: 4.9-3.5-2.5. The value of the sum of muscle torque of the left upper extremities was significantly correlated only with mesomorphic component. Mesomorphic and ectomorphic components correlated significantly with values of maximal power measured during ACMJ and CMJ. Power output measured in maximal cycle ergometer exercise bouts at increasing external loads equal to 2.5, 5.0 and 7.5% of BW was significantly correlated with endomorphy, mesomorphy and ectomorphy.

A Practice Indexes for Improving Facial Movements of Brass Instrument Players

NASA Astrophysics Data System (ADS)

Ito, Kyoko; Hirano, Takeshi; Noto, Kazufumi; Nishida, Shogo; Ohtsuki, Tatsuyuki

Two experimental studies have been conducted in order to propose practice indexes for the improvement of the embouchure of French horn players, two experimental studies have been conducted. In both studies, the same task was performed by advanced and amateur French horn players. The first study investigated the activity, while performing the above-mentioned task, of the 5 facial muscles (levator labii superioris, zygomaticus major, depressor anguli oris, depressor labii inferioris, and risorius muscles) on the right side of the face by surface electromyography, and the facial movement on the left side of the face by attaching two markers above each muscle and using two high-speed cameras simultaneously. The results of the study showed that it is possible for the four markers around the lower lip to practice indexes. The second study evaluated whether the above-mentioned markers are appropriate as practice indexes using a 3-D tracking system and questionnaires. The results showed that both the advanced and the amateur players assessed that the markers were suitable as practice indexes for improving the embouchure. This set of approaches could be useful for selecting practice indexes and developing scientific practice methods not only for the French horn but also for other instruments and other fields.

Neuromuscular Risk Factors for Knee and Ankle Ligament Injuries in Male Youth Soccer Players

PubMed Central

Read, Paul J.; Oliver, Jon L.; De Ste Croix, Mark B. A.; Myer, Gregory D.; Lloyd, Rhodri S.

2017-01-01

Injuries reported in male youth soccer players most commonly occur in the lower extremities, and include a high proportion of ligament sprains at the ankle and knee with a lower proportion of overuse injuries. There is currently a paucity of available literature that examines age- and sex-specific injury risk factors for such injuries within youth soccer players. Epidemiological data have reported movements that lead to non-contact ligament injury include running, twisting and turning, over-reaching and landing. Altered neuromuscular control during these actions has been suggested as a key mechanism in females and adult populations; however, data available in male soccer players is sparse. The focus of this article is to review the available literature and elucidate prevalent risk factors pertaining to male youth soccer players which may contribute to their relative risk of injury. PMID:26856339

Role of Gaze Cues in Interpersonal Motor Coordination: Towards Higher Affiliation in Human-Robot Interaction.

PubMed

Khoramshahi, Mahdi; Shukla, Ashwini; Raffard, Stéphane; Bardy, Benoît G; Billard, Aude

2016-01-01

The ability to follow one another's gaze plays an important role in our social cognition; especially when we synchronously perform tasks together. We investigate how gaze cues can improve performance in a simple coordination task (i.e., the mirror game), whereby two players mirror each other's hand motions. In this game, each player is either a leader or follower. To study the effect of gaze in a systematic manner, the leader's role is played by a robotic avatar. We contrast two conditions, in which the avatar provides or not explicit gaze cues that indicate the next location of its hand. Specifically, we investigated (a) whether participants are able to exploit these gaze cues to improve their coordination, (b) how gaze cues affect action prediction and temporal coordination, and (c) whether introducing active gaze behavior for avatars makes them more realistic and human-like (from the user point of view). 43 subjects participated in 8 trials of the mirror game. Each subject performed the game in the two conditions (with and without gaze cues). In this within-subject study, the order of the conditions was randomized across participants, and subjective assessment of the avatar's realism was assessed by administering a post-hoc questionnaire. When gaze cues were provided, a quantitative assessment of synchrony between participants and the avatar revealed a significant improvement in subject reaction-time (RT). This confirms our hypothesis that gaze cues improve the follower's ability to predict the avatar's action. An analysis of the pattern of frequency across the two players' hand movements reveals that the gaze cues improve the overall temporal coordination across the two players. Finally, analysis of the subjective evaluations from the questionnaires reveals that, in the presence of gaze cues, participants found it not only more human-like/realistic, but also easier to interact with the avatar. This work confirms that people can exploit gaze cues to predict another person's movements and to better coordinate their motions with their partners, even when the partner is a computer-animated avatar. Moreover, this study contributes further evidence that implementing biological features, here task-relevant gaze cues, enable the humanoid robotic avatar to appear more human-like, and thus increase the user's sense of affiliation.

Tracking of Ball and Players in Beach Volleyball Videos

PubMed Central

Gomez, Gabriel; Herrera López, Patricia; Link, Daniel; Eskofier, Bjoern

2014-01-01

This paper presents methods for the determination of players' positions and contact time points by tracking the players and the ball in beach volleyball videos. Two player tracking methods are compared, a classical particle filter and a rigid grid integral histogram tracker. Due to mutual occlusion of the players and the camera perspective, results are best for the front players, with 74,6% and 82,6% of correctly tracked frames for the particle method and the integral histogram method, respectively. Results suggest an improved robustness against player confusion between different particle sets when tracking with a rigid grid approach. Faster processing and less player confusions make this method superior to the classical particle filter. Two different ball tracking methods are used that detect ball candidates from movement difference images using a background subtraction algorithm. Ball trajectories are estimated and interpolated from parabolic flight equations. The tracking accuracy of the ball is 54,2% for the trajectory growth method and 42,1% for the Hough line detection method. Tracking results of over 90% from the literature could not be confirmed. Ball contact frames were estimated from parabolic trajectory intersection, resulting in 48,9% of correctly estimated ball contact points. PMID:25426936

Increase in ACL and PCL injuries after implementation of a new professional football league.

PubMed

Krutsch, Werner; Zeman, Florian; Zellner, Johannes; Pfeifer, Christian; Nerlich, Michael; Angele, Peter

2016-07-01

In the season 2008-2009, a third professional football league was established in Germany. This study analysed the influence of increased training and playing intensity on severe knee injuries in football players. In a prospective controlled one-season trial, injury incidence and injury patterns of players of the newly established professional football league were analysed, particularly with regard to ruptures of the anterior (ACL) and posterior (PCL) cruciate ligaments. Players of the highest amateur level served as a control group. Four hundred and eight players of 24 teams were allocated to two groups. The overall training exposure was significantly (p < 0.001) higher in the new professional league (335.3 h per player) than at the amateur level (286.6 h per player). Players at both levels showed similar overall injury rates and injury patterns. However, players in the professional league had a significantly higher (p = 0.04) incidence of ACL and PCL injuries, than players at the amateur level. More than 90 % of all ACL and PCL ruptures in both groups were sustained by players, who had played at least one level lower in the previous season. In addition, injuries of players who had sustained repeat injuries over the season were more severe. The introduction of a new professional football league increased the training and playing intensity of players as well as the number of ACL and PCL ruptures. A specific injury prevention concept, particularly for players facing rapidly increasing training and playing intensity, seems to be mandatory. Prospective controlled cohort study, Level II.

Charter School Authorizing: Are States Making the Grade?

ERIC Educational Resources Information Center

Palmer, Louann Bierlein; Gau, Rebecca

2003-01-01

When the charter school movement began in the early 1990's, one key set of players received little attention: the public entities that sponsor or authorize these unconventional schools. A charter is properly understood as a contract between two parties, the school operator and the authorizer. For the charter movement to succeed, both must do their…

Comparison of Activity Profiles and Physiological Demands Between International Rugby Sevens Matches and Training.

PubMed

Higham, Dean G; Pyne, David B; Anson, Judith M; Hopkins, Will G; Eddy, Anthony

2016-05-01

The specificity of contemporary training practices of international rugby sevens players is unknown. We quantified the positional group-specific activity profiles and physiological demands of on-field training activities and compared these with match demands. Twenty-two international matches and 63 rugby-specific training drills were monitored in 25 backs and 17 forwards from a national squad of male rugby sevens players over a 21-month period. Drills were classified into 3 categories: low-intensity skill refining (n = 23 drills, 560 observations), moderate- to high-intensity skill refining (n = 28 drills, 600 observations), and game simulation (n = 12 drills, 365 observations). Movement patterns (via Global Positioning System devices) and physiological load (via heart rate monitors) were recorded for all activities, and the differences between training and matches were quantified using magnitude-based inferential statistics. Distance covered in total and at ≥3.5 m·s, maximal velocity, and frequency of accelerations and decelerations were lower for forwards during competition compared with those for backs by a small but practically important magnitude. No clear positional group differences were observed for physiological load during matches. Training demands exceeded match demands only for frequency of decelerations of forwards during moderate- to high-intensity skill-refining drills and only by a small amount. Accelerations and distance covered at ≥6 m·s were closer to match values for forwards than for backs during all training activities, but training drills consistently fell below the demands of international competition. Coaches could therefore improve physical and physiological specificity by increasing the movement demands and intensity of training drills.

Time - motion analysis of professional rugby union players during match-play.

PubMed

Deutsch, M U; Kearney, G A; Rehrer, N J

2007-02-15

The aim of this study was to quantify the movement patterns of various playing positions during professional rugby union match-play, such that the relative importance of aerobic and anaerobic energy pathways to performance could be estimated. Video analysis was conducted of individual players (n=29) from the Otago Highlanders during six "Super 12" representative fixtures. Each movement was coded as one of six speeds of locomotion (standing still, walking, jogging, cruising, sprinting, and utility), three states of non-running intensive exertion (rucking/mauling, tackling, and scrummaging), and three discrete activities (kicking, jumping, passing). The results indicated significant demands on all energy systems in all playing positions, yet implied a greater reliance on anaerobic glycolytic metabolism in forwards, due primarily to their regular involvement in non-running intense activities such as rucking, mauling, scrummaging, and tackling. Positional group comparisons indicated that while the greatest differences existed between forwards and backs, each positional group had its own unique demands. Front row forwards were mostly involved in activities involving gaining/retaining possession, back row forwards tended to play more of a pseudo back-line role, performing less rucking/mauling than front row forwards, yet being more involved in aspects of broken play such as sprinting and tackling. While outside backs tended to specialize in the running aspects of play, inside backs tended to show greater involvement in confrontational aspects of play such as rucking/mauling and tackling. These results suggest that rugby training and fitness testing should be tailored specifically to positional groups rather than simply differentiating between forwards and backs.

The importance of open- and closed-skill agility for team selection of adult male basketball players.

PubMed

Scanlan, A T; Tucker, P S; Dalbo, V J

2015-05-01

Open-skill agility qualities have yet to be described in adult male basketball players. Further, the importance of open- and closed-skill agility for team selection remains unknown. Thus, this study aimed to: 1) describe the open- and closed-skill agility of adult male basketball players; and 2) compare these properties between starting and non-starting players. A cross-sectional between-group design was used. Six starting (playing time: 30.1 ± 8.8 min; age: 30.5 ± 4.8 years; height: 192.1 ± 7.7 cm; body mass: 100.5 ± 15.0 kg; VO(2max): 48.4 ± 6.6 mL∙kg⁻¹∙min⁻¹) and six non-starting (4.3 ± 3.6 min; 21.3 ± 5 years; 185.7 ± 7.4 cm; 94.4 ± 17.9 kg; 50.6 ± 3.9 mL∙kg⁻¹∙min⁻¹) state-level basketball players completed multiple trials for the Change of Direction Speed Test (CODST) and Reactive Agility Test (RAT). No statistically significant between-group differences were evident for CODST movement time (starters: 1.652 ± 0.047 s; non-starters: 1.626 ± 0.040 s, P=0.68), RAT response time (starters: 307.5 ± 100.5 ms; non-starters: 426.5 ± 140.7 ms, P=0.12), and RAT decision-making time (starters: 110.7 ± 11.0 ms; non-starters: 147.3 ± 14.2 ms, P=0.08). However, starters (2.001 ± 0.051 s) possessed significantly (P=0.02) faster RAT total movement times than non-starters (2.182 ± 0.040 s). These data support the utility of perceptual and cognitive components of agility performance in distinguishing starting from non-starting players in basketball. Consequently, basketball coaching and conditioning staff should incorporate sport-specific reactive training drills for all players during the annual conditioning plan.

The Physical and Athletic Performance Characteristics of Division I Collegiate Female Soccer Players by Position.

PubMed

Lockie, Robert G; Moreno, Matthew R; Lazar, Adrina; Orjalo, Ashley J; Giuliano, Dominic V; Risso, Fabrice G; Davis, DeShaun L; Crelling, Jeff B; Lockwood, John R; Jalilvand, Farzad

2018-02-01

Lockie, RG, Moreno, MR, Lazar, A, Orjalo, AJ, Giuliano, DV, Risso, FG, Davis, DL, Crelling, JB, Lockwood, JR, and Jalilvand, F. The physical and athletic performance characteristics of Division I collegiate female soccer players by position. J Strength Cond Res 32(2): 334-343, 2018-Playing positions in soccer can exhibit different movement demands during a match, contributing to variations in physical and performance characteristics. National Collegiate Athletic Association (NCAA) soccer features different substitution rules when compared to FIFA-sanctioned matches, which could influence each players' characteristics. Therefore, this study determined the athletic performance characteristics of Division I female soccer players. Twenty-six players (3 goalkeepers; 8 defenders; 10 midfielders; 5 forwards) from the same squad completed assessments of: lower-body power (vertical and standing broad jump); linear (0-5, 0-10, 0-30 meter [m] sprint intervals) and change-of-direction (pro-agility shuttle; arrowhead change-of-direction speed test) speed; and soccer-specific fitness (Yo-Yo Intermittent Recovery Test [YYIRT] levels 1 and 2). Players were split into position groups, and a Kruskal-Wallis H test with post hoc pairwise analyses (p ≤ 0.05) calculated significant between-group differences. There were no differences in age, height, or body mass between the positions. Midfielders had a faster 0-5 m time compared with the defenders (p = 0.017) and the goalkeepers (p = 0.030). The defenders (p = 0.011) and midfielders (p = 0.013) covered a greater YYIRT2 distance compared with the goalkeepers. There were no other significant between-position differences. Overall, Division I collegiate female players from the same squad demonstrated similar characteristics as measured by soccer-specific performance tests, which could allow for flexibility in position assignments. However, a relatively homogenous squad could also indicate commonality in training prescription, particularly regarding acceleration and high-intensity running. Strength and conditioning coaches may have to consider the specific movement demands of individual positions when training these capacities.

Injury risk is low among world-class volleyball players: 4-year data from the FIVB Injury Surveillance System

PubMed Central

Bere, Tone; Kruczynski, Jacek; Veintimilla, Nadège; Hamu, Yuichiro; Bahr, Roald

2015-01-01

Background Little is known about the rate and pattern of injuries in international volleyball competition. Objective To describe the risk and pattern of injuries among world-class players based on data from the The International Volleyball Federation (FIVB) Injury Surveillance System (ISS) (junior and senior, male and female). Methods The FIVB ISS is based on prospective registration of injuries by team medical staff during all major FIVB tournaments (World Championships, World Cup, World Grand Prix, World League, Olympic Games). This paper is based on 4-year data (September 2010 to November 2014) obtained through the FIVB ISS during 32 major FIVB events (23 senior and 9 junior). Results The incidence of time-loss injuries during match play was 3.8/1000 player hours (95% CI 3.0 to 4.5); this was greater for senior players than for junior players (relative risk: 2.04, 1.29 to 3.21), while there was no difference between males and females (1.04, 0.70 to 1.55). Across all age and sex groups, the ankle was the most commonly injured body part (25.9%), followed by the knee (15.2%), fingers/thumb (10.7%) and lower back (8.9%). Injury incidence was greater for centre players and lower for liberos than for other player functions; injury patterns also differed between player functions. Conclusions Volleyball is a very safe sport, even at the highest levels of play. Preventive measures should focus on acute ankle and finger sprains, and overuse injuries in the knee, lower back and shoulder. PMID:26194501

Physiologically Modulating Videogames or Simulations which Use Motion-Sensing Input Devices

NASA Technical Reports Server (NTRS)

Blanson, Nina Marie (Inventor); Stephens, Chad L. (Inventor); Pope, Alan T. (Inventor)

2017-01-01

New types of controllers allow a player to make inputs to a video game or simulation by moving the entire controller itself or by gesturing or by moving the player's body in whole or in part. This capability is typically accomplished using a wireless input device having accelerometers, gyroscopes, and a camera. The present invention exploits these wireless motion-sensing technologies to modulate the player's movement inputs to the videogame based upon physiological signals. Such biofeedback-modulated video games train valuable mental skills beyond eye-hand coordination. These psychophysiological training technologies enhance personal improvement, not just the diversion, of the user.

A Novel Computer-Based Set-Up to Study Movement Coordination in Human Ensembles

PubMed Central

Alderisio, Francesco; Lombardi, Maria; Fiore, Gianfranco; di Bernardo, Mario

2017-01-01

Existing experimental works on movement coordination in human ensembles mostly investigate situations where each subject is connected to all the others through direct visual and auditory coupling, so that unavoidable social interaction affects their coordination level. Here, we present a novel computer-based set-up to study movement coordination in human groups so as to minimize the influence of social interaction among participants and implement different visual pairings between them. In so doing, players can only take into consideration the motion of a designated subset of the others. This allows the evaluation of the exclusive effects on coordination of the structure of interconnections among the players in the group and their own dynamics. In addition, our set-up enables the deployment of virtual computer players to investigate dyadic interaction between a human and a virtual agent, as well as group synchronization in mixed teams of human and virtual agents. We show how this novel set-up can be employed to study coordination both in dyads and in groups over different structures of interconnections, in the presence as well as in the absence of virtual agents acting as followers or leaders. Finally, in order to illustrate the capabilities of the architecture, we describe some preliminary results. The platform is available to any researcher who wishes to unfold the mechanisms underlying group synchronization in human ensembles and shed light on its socio-psychological aspects. PMID:28649217

Science of rugby league football: a review.

PubMed

Gabbett, Tim J

2005-09-01

The purpose of this paper is to provide a comprehensive review of the science of rugby league football at all levels of competition (i.e. junior, amateur, semi-professional, professional), with special reference to all discipline-specific scientific research performed in rugby league (i.e. physiological, psychological, injury epidemiology, strength and conditioning, performance analysis). Rugby league football is played at junior and senior levels in several countries worldwide. A rugby league team consists of 13 players (6 forwards and 7 backs). The game is played over two 30 - 40 min halves (depending on the standard of competition) separated by a 10 min rest interval. Several studies have documented the physiological capacities and injury rates of rugby league players. More recently, studies have investigated the physiological demands of competition. Interestingly, the physiological capacities of players, the incidence of injury and the physiological demands of competition all increase as the playing standard is increased. Mean blood lactate concentrations of 5.2, 7.2 and 9.1 mmol . l(-1) have been reported during competition for amateur, semi-professional and professional rugby league players respectively. Mean heart rates of 152 beats . min(-1) (78% of maximal heart rate), 166 beats . min(-1) (84% of maximal heart rate) and 172 beats . min(-1) (93% of maximal heart rate) have been recorded for amateur, semi-professional and junior elite rugby league players respectively. Skill-based conditioning games have been used to develop the skill and fitness of rugby league players, with mean heart rate and blood lactate responses during these activities almost identical to those obtained during competition. In addition, recent studies have shown that most training injuries are sustained in traditional conditioning activities that involve no skill component (i.e. running without the ball), whereas the incidence of injuries while participating in skill-based conditioning games is low. Collaborative research among the various sport science disciplines is required to identify strategies to reduce the incidence of injury and enhance the performance of rugby league players. An understanding of the movement patterns and physiological demands of different positions at all standards of competition would allow the development of strength and conditioning programmes to meet the precise requirements of these positions. Finally, studies investigating the impact of improvements in physiological capacities (including the effect of different strength and conditioning programmes) on rugby league playing performance are warranted.

Biochemical, physical and tactical analysis of a simulated game in young soccer players.

PubMed

Aquino, Rodrigo L; Gonçalves, Luiz G; Vieira, Luiz H; Oliveira, Lucas P; Alves, Guilherme F; Santiago, Paulo R; Puggina, Enrico F

2016-12-01

The objectives of this study were to describe and compare the displacement patterns and the tactical performance of the players in the first to the second game time and verify possible associations between indirect markers of muscle damage with displacement patterns in a simulated game played by young soccer players. Eighteen young soccer players were submitted to a simulated game and two blood collections, one before and another 30 minutes post-game to analyze the behavior of creatine kinase and lactate dehydrogenase enzymes. The patterns of displacement and tactics variables were obtained through functions developed in MATLAB environment (MathWorks, Inc., Natick, MA, USA). It is observed a significant increase in average speed (P=0.05), number of sprints (P<0.001), the percentage the total distance covered at high intensity (P<0.001) and tactical variables (team surface area: P=0.002; spreading: P=0.001) in the second period of the simulated game. In addition, there was significant reduction in the percentage of the total distance at low intensity (P≤0.05) in the second period, and there was a strong association between the percentage of change delta of creatine kinase and lactate dehydrogenase with the displacement patterns in the simulated game. The results show that indirect markers of muscle damage have great association with displacement patterns in game performed in training conditions for young soccer players, evidencing a need for reflection on the post-training recovery sessions strategies, contributing to better planning of sessions throughout the macrocycle.

Gender-specific activity demands experienced during semiprofessional basketball game play.

PubMed

Scanlan, Aaron T; Dascombe, Ben J; Kidcaff, Andrew P; Peucker, Jessica L; Dalbo, Vincent J

2015-07-01

To compare game activity demands between female and male semiprofessional basketball players. Female (n=12) and male (n=12) semiprofessional basketball players were monitored across 3 competitive games. Time-motion-analysis procedures quantified player activity into predefined movement categories across backcourt (BC) and frontcourt (FC) positions. Activity frequencies, durations, and distances were calculated relative to live playing time (min). Work:rest ratios were also calculated using the video data. Game activity was compared between genders for each playing position and all players. Female players performed at greater running work-rates than male players (45.7±1.4 vs. 42.1±1.7 m/min, P=.05), while male players performed more dribbling than female players (2.5±0.3 vs. 3.0±0.2 s/min; 8.4±0.3 vs. 9.7±0.7 m/min, P=.05). Positional analyses revealed that female BC players performed more low-intensity shuffling (P=.04) and jumping (P=.05), as well as longer (P=.04) jogging durations, than male BC players. Female FC players executed more upper-body activity (P=.03) and larger work:rest ratios (P<.001) than male FC players. No significant gender differences were observed in the overall intermittent demands, distance traveled, high-intensity shuffling activity, and sprinting requirements during game play. These findings indicate that gender-specific running and dribbling differences might exist in semiprofessional basketball. Furthermore, position-specific variations between female and male basketball players should be considered. These data may prove useful in the development of gender-specific conditioning plans relative to playing position in basketball.

Injury risk is low among world-class volleyball players: 4-year data from the FIVB Injury Surveillance System.

PubMed

Bere, Tone; Kruczynski, Jacek; Veintimilla, Nadège; Hamu, Yuichiro; Bahr, Roald

2015-09-01

Little is known about the rate and pattern of injuries in international volleyball competition. To describe the risk and pattern of injuries among world-class players based on data from the The International Volleyball Federation (FIVB) Injury Surveillance System (ISS) (junior and senior, male and female). The FIVB ISS is based on prospective registration of injuries by team medical staff during all major FIVB tournaments (World Championships, World Cup, World Grand Prix, World League, Olympic Games). This paper is based on 4-year data (September 2010 to November 2014) obtained through the FIVB ISS during 32 major FIVB events (23 senior and 9 junior). The incidence of time-loss injuries during match play was 3.8/1000 player hours (95% CI 3.0 to 4.5); this was greater for senior players than for junior players (relative risk: 2.04, 1.29 to 3.21), while there was no difference between males and females (1.04, 0.70 to 1.55). Across all age and sex groups, the ankle was the most commonly injured body part (25.9%), followed by the knee (15.2%), fingers/thumb (10.7%) and lower back (8.9%). Injury incidence was greater for centre players and lower for liberos than for other player functions; injury patterns also differed between player functions. Volleyball is a very safe sport, even at the highest levels of play. Preventive measures should focus on acute ankle and finger sprains, and overuse injuries in the knee, lower back and shoulder. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Practice effects on intra-team synergies in football teams.

PubMed

Silva, Pedro; Chung, Dante; Carvalho, Thiago; Cardoso, Tiago; Davids, Keith; Araújo, Duarte; Garganta, Júlio

2016-04-01

Developing synchronised player movements for fluent competitive match play is a common goal for coaches of team games. An ecological dynamics approach advocates that intra-team synchronization is governed by locally created information, which specifies shared affordances responsible for synergy formation. To verify this claim we evaluated coordination tendencies in two newly-formed teams of recreational players during association football practice games, weekly, for fifteen weeks (thirteen matches). We investigated practice effects on two central features of synergies in sports teams - dimensional compression and reciprocal compensation here captured through near in-phase modes of coordination and time delays between coupled players during forward and backwards movements on field while attacking and defending. Results verified that synergies were formed and dissolved rapidly as a result of the dynamic creation of informational properties, perceived as shared affordances among performers. Practising once a week led to small improvements in the readjustment delays between co-positioning team members, enabling faster regulation of coordinated team actions. Mean values of the number of player and team synergies displayed only limited improvements, possibly due to the timescales of practice. No relationship between improvements in dimensional compression and reciprocal compensation were found for number of shots, amount of ball possession and number of ball recoveries made. Findings open up new perspectives for monitoring team coordination processes in sport. Copyright © 2015 Elsevier B.V. All rights reserved.

The geometry of expertise

PubMed Central

Leone, María J.; Fernandez Slezak, Diego; Cecchi, Guillermo A.; Sigman, Mariano

2014-01-01

Theories of expertise based on the acquisition of chunk and templates suggest a differential geometric organization of perception between experts and novices. It is implied that expert representation is less anchored by spatial (Euclidean) proximity and may instead be dictated by the intrinsic relation in the structure and grammar of the specific domain of expertise. Here we set out to examine this hypothesis. We used the domain of chess which has been widely used as a tool to study human expertise. We reasoned that the movement of an opponent piece to a specific square constitutes an external cue and the reaction of the player to this “perturbation” should reveal his internal representation of proximity. We hypothesized that novice players will tend to respond by moving a piece in closer squares than experts. Similarly, but now in terms of object representations, we hypothesized weak players will more likely focus on a specific piece and hence produce sequence of actions repeating movements of the same piece. We capitalized on a large corpus of data obtained from internet chess servers. Results showed that, relative to experts, weaker players tend to (1) produce consecutive moves in proximal board locations, (2) move more often the same piece and (3) reduce the number of remaining pieces more rapidly, most likely to decrease cognitive load and mental effort. These three principles might reflect the effect of expertise on human actions in complex setups. PMID:24550869

Divergent oral cavity motor strategies between healthy elite and dystonic horn players.

PubMed

Iltis, Peter W; Frahm, Jens; Voit, Dirk; Joseph, Arun; Schoonderwaldt, Erwin; Altenmüller, Eckart

2015-01-01

This paper describes the use of real-time magnetic resonance imaging in visualizing and quantifying oral cavity motor strategies employed by 6 healthy, elite horn players and 5 horn players with embouchure dystonia. Serial images with an acquisition time of 33.3 ms were obtained from each performer during execution of an 11-note harmonic series encompassing 2.5 octaves on a magnetic resonance imaging-compatible horn. A customized MATLAB toolkit was employed for the extraction of line profiles from magnetic resonance imaging films allowing comparative analyses between elite and dystonic horn players. The data demonstrate differing motor strategies, particularly in moving from the 6th through 9th harmonics. The elite horn player strategy features elevation and anterior displacement of the tongue during ascending sequences, whereas dystonic players showed significantly less movement. The elite horn players thus narrowed the air channel on higher notes, presumably affording faster airflow for vibration of the lips at higher frequencies. We postulate that failure to employ this strategy by dystonic horn players may require greater tension in the embouchure muscles to compensate for slower air speed. Though this may simply be an expression of or adaptation for dystonia, the possibility that it may be a contributing factor in the development of embouchure dystonia is suggested.

Ground Reaction Forces and Throwing Performance in Elite and Novice Players in Two Types of Handball Shot

PubMed Central

Rousanoglou, Elissavet; Noutsos, Konstantinos; Bayios, Ioannis; Boudolos, Konstantinos

2014-01-01

The purpose of this study was to examine the differences in the ground reaction force (GRF) patterns between elite and novice players during two types of handball shots, as well as the relationships between throwing performance and the GRF variables. Ball velocity and throwing accuracy were measured during jump shots and 3-step shots performed by 15 elite and 15 novice players. The GRF pattern was recorded for the vertical and the anterior-posterior GRF components (Kistler forceplate type-9281, 750Hz). One-way ANOVA was used for the group differences and the Pearson coefficient for the correlation between throwing performance and GRF variables (SPSS 21.0, p ≤ 0.05). The elite players performed better in both types of shot. Both groups developed consistent and similar GRF patterns, except for the novices’ inconsistent Fz pattern in the 3-step shot. The GRF variables differed significantly between groups in the 3-step shot (p ≤ 0.05). Significant correlations were found only for ball velocity and predominantly for the novice players during the 3-step shot (p ≤ 0.05). The results possibly highlight a shortage in the novice ability to effectively reduce their forward momentum so as to provide a stable base of support for the momentum transfer up the kinetic chain, a situation that may predispose athletes to injury. PMID:25031672

Ground reaction forces and throwing performance in elite and novice players in two types of handball shot.

PubMed

Rousanoglou, Elissavet; Noutsos, Konstantinos; Bayios, Ioannis; Boudolos, Konstantinos

2014-03-27

The purpose of this study was to examine the differences in the ground reaction force (GRF) patterns between elite and novice players during two types of handball shots, as well as the relationships between throwing performance and the GRF variables. Ball velocity and throwing accuracy were measured during jump shots and 3-step shots performed by 15 elite and 15 novice players. The GRF pattern was recorded for the vertical and the anterior-posterior GRF components (Kistler forceplate type-9281, 750Hz). One-way ANOVA was used for the group differences and the Pearson coefficient for the correlation between throwing performance and GRF variables (SPSS 21.0, p ≤ 0.05). The elite players performed better in both types of shot. Both groups developed consistent and similar GRF patterns, except for the novices' inconsistent Fz pattern in the 3-step shot. The GRF variables differed significantly between groups in the 3-step shot (p ≤ 0.05). Significant correlations were found only for ball velocity and predominantly for the novice players during the 3-step shot (p ≤ 0.05). The results possibly highlight a shortage in the novice ability to effectively reduce their forward momentum so as to provide a stable base of support for the momentum transfer up the kinetic chain, a situation that may predispose athletes to injury.

Unintended imitation affects success in a competitive game.

PubMed

Naber, Marnix; Vaziri Pashkam, Maryam; Nakayama, Ken

2013-12-10

Imitation typically occurs in social contexts where people interact and have common goals. Here, we show that people are also highly susceptible to imitate each other in a competitive context. Pairs of players performed a competitive and fast-reaching task (a variant of the arcade whac-a-mole game) in which money could be earned if players hit brief-appearing visual targets on a large touchscreen before their opponents. In three separate experiments, we demonstrate that reaction times and movements were highly correlated within pairs of players. Players affected their success by imitating each other, and imitation depended on the visibility of the opponent's behavior. Imitation persisted, despite the competitive and demanding nature of the game, even if this resulted in lower scores and payoffs and even when there was no need to counteract the opponent's actions.

Activity Profiles in International Women's Team Handball Using PlayerLoad.

PubMed

Wik, Eirik H; Luteberget, Live S; Spencer, Matt

2017-08-01

Team handball matches place diverse physical demands on players, which may result in fatigue and decreased activity levels. However, previous speed-based methods of quantifying player activity may not be sensitive for capturing short-lasting team-handball-specific movements. To examine activity profiles of a women's team handball team and individual player profiles, using inertial measurement units. Match data were obtained from 1 women's national team in 9 international matches (N = 85 individual player samples), using the Catapult OptimEye S5. PlayerLoad/min was used as a measure of intensity in 5- and 10-min periods. Team profiles were presented as relative to the player's match means, and individual profiles were presented as relative to the mean of the 5-min periods with >60% field time. A high initial intensity was observed for team profiles and for players with ≥2 consecutive periods of play. Substantial declines in PlayerLoad/min were observed throughout matches for the team and for players with several consecutive periods of field time. These trends were found for all positional categories. Intensity increased substantially in the final 5 min of the first half for team profiles. Activity levels were substantially lower in the 5 min after a player's most intense period and were partly restored in the subsequent 5-min period. Possible explanations for the observed declines in activity profiles for the team and individual players include fatigue, situational factors, and pacing. However, underlying mechanisms were not accounted for, and these assumptions are therefore based on previous team-sport studies.

Effects of small-sided games on physical conditioning and performance in young soccer players.

PubMed

Katis, Athanasios; Kellis, Eleftherios

2009-01-01

The purpose of this study was to examine, first, the movement actions performed during two different small-sided games and, second, their effects on a series of field endurance and technical tests. Thirty-four young soccer players (age: 13 ± 0.9 yrs; body mass: 62.3 ± 15.1 kg; height: 1.65 ± 0.06 m) participated in the study. Small-sided games included three-a-side (3 versus 3 players) and six-a-side (6 versus 6 players) games consisting of 10 bouts of 4 min duration with 3 min active recovery between bouts. Soccer player performance was evaluated using five field tests: a) 30m sprint, b) throw-in for distance, c) Illinois Agility Test, d) dribbling the ball and e) horizontal jump before, in the middle and after the implementation of both game situations. Heart rate was monitored during the entire testing session. Each game was also filmed to measure soccer movements within the game. The ANOVA analysis indicated that the three-a- side games displayed significantly higher heart rate values compared with the six-a-side games (p < 0.05). The number of short passes, kicks, tackles, dribbles and scoring goals were significantly higher during the three-a-side compared with the six-a-side game condition (p < 0. 05) while players performed more long passes and headed the ball more often during the six-a-side (p < 0.05). After the three-a-side games, there was a significant decline in sprint and agility performance (p < 0.05), while after both game conditions significant alterations in the throw-in and the horizontal jump performance were observed (p < 0.05). The results of the present study indicated that three-a-side games provide higher stimulus for physical conditioning and technical improvement than six-a-side games and their use for training young soccer players is recommended. Key pointsThree-a-side games display higher HR compared with six-a-side games.In the three-a-side games players performed more short passes, kicks, dribbles, tackles and scored more goals compared with the six-a-side games.Impairment in endurance and field test performance was observed mainly after three-a-side games.The use of the three-a-side games to develop physical fitness and technique in young soccer players is recommended.

Difference in plantar pressure between the preferred and non‐preferred feet in four soccer‐related movements

PubMed Central

Wong, Pui‐lam; Chamari, Karim; Chaouachi, Anis; De Wei Mao; Wisløff, Ulrik; Hong, Youlian

2007-01-01

Objective and participants The present study measured the difference in plantar pressure between the preferred and non‐preferred foot in four soccer‐related movements in 15 male university soccer players (mean (SD) age 20.9 (1.3) years, mean (SD) height 173 (4) cm and mean (SD) weight 61.7 (3.6) kg). Design To record plantar pressure distribution, players randomly wore three types of soccer shoes (classical 6‐stud and 12‐stud, and specially designed 12‐stud) embedded with an insole pressure recorder device with 99 sensors, divided into 10 areas for analysis. Plantar pressure was recorded in five successful trials in each of the four soccer‐related movements: running (at 3.3 m/s), sideward cutting, 45° cutting and landing from a vertical jump. Results Plantar pressures of the preferred and non‐preferred foot were different in 115 of 120 comparisons. The overall plantar pressure of the preferred foot was higher than that of the non‐preferred foot. Specifically, in each of the four movements, higher pressure was found in the preferred foot during the take‐off phase, whereas this was found in the non‐preferred foot during the landing phase. This would suggest a tendency of the preferred foot for higher motion force and of the non‐preferred foot for a greater role in body stabilisation. Conclusions The data indicate that the preferred and non‐preferred foot should be treated independently with regard to strength/power training to avoid unnecessary injuries. Different shoes/insoles and different muscular strengthening programmes are thus suggested for each of the soccer player's feet. PMID:17138639

Real-time MRI comparisons of brass players: A methodological pilot study.

PubMed

Iltis, Peter W; Schoonderwaldt, Erwin; Zhang, Shuo; Frahm, Jens; Altenmüller, Eckart

2015-08-01

This paper describes the use of real-time MRI at 30 frames/s in studying motor function within the oropharyngeal cavity of a trumpet, horn, trombone, and tuba player. Using Image J and customized MB-Ruler Pro software, analyses of discrete 33.3 ms snapshots of motion extracted from real-time MRI films obtained during an ascending five note sequence performed on a plastic practice device (B.E.R.P.) revealed inter-instrument differences in oropharyngeal cavity size and tongue conformation when moving from lower to higher notes. Tuba and trombone show a progressive decrease in oropharyngeal area featuring an upward and forward displacement of the tongue. Trumpet showed progressive increases in oropharyngeal area, with the posterior compartment showing the largest change, while horn essentially showed no change. A novel dynamic quantitative analysis method is also described utilizing Matlab. This method employs user-specified line profiles, aligned to the direction of the movement of interest. It takes advantage of time-varying pixel luminescence to derive spatial and temporal gradients. These gradients make possible the acquisition of kinematic data to describe movement in terms of slower position changes (spatial gradient) as well as fast, articulatory movements (temporal gradient). Spatial gradient analysis for the trumpet player demonstrates a progressive raising of the tongue during the ascending five note exercise. Temporal gradient analysis of double-tonguing revealed similarities in range of motion, anti-phase behavior, and frequency across instruments with respect to movements of the tongue tip and back of tongue. The paper concludes by making recommendations for extending these methods to studying musician's dystonia. Copyright © 2015 Elsevier B.V. All rights reserved.

Application of a tri-axial accelerometer to estimate jump frequency in volleyball.

PubMed

Jarning, Jon M; Mok, Kam-Ming; Hansen, Bjørge H; Bahr, Roald

2015-03-01

Patellar tendinopathy is prevalent among athletes, and most likely associated with a high jumping load. If methods for estimating jump frequency were available, this could potentially assist in understanding and preventing this condition. The objective of this study was to explore the possibility of using peak vertical acceleration (PVA) or peak resultant acceleration (PRA) measured by an accelerometer to estimate jump frequency. Twelve male elite volleyball players (22.5 ± 1.6 yrs) performed a training protocol consisting of seven typical motion patterns, including jumping and non-jumping movements. Accelerometer data from the trial were obtained using a tri-axial accelerometer. In addition, we collected video data from the trial. Jump-float serving and spike jumping could not be distinguished from non-jumping movements using differences in PVA or PRA. Furthermore, there were substantial inter-participant differences in both the PVA and the PRA within and across movement types (p < 0.05). These findings suggest that neither PVA nor PRA measured by a tri-axial accelerometer is an applicable method for estimating jump frequency in volleyball. A method for acquiring real-time estimates of jump frequency remains to be verified. However, there are several alternative approaches, and further investigations are needed.

Sports teams as complex adaptive systems: manipulating player numbers shapes behaviours during football small-sided games.

PubMed

Silva, Pedro; Vilar, Luís; Davids, Keith; Araújo, Duarte; Garganta, Júlio

2016-01-01

Small-sided and conditioned games (SSCGs) in sport have been modelled as complex adaptive systems. Research has shown that the relative space per player (RSP) formulated in SSCGs can impact on emergent tactical behaviours. In this study we adopted a systems orientation to analyse how different RSP values, obtained through manipulations of player numbers, influenced four measures of interpersonal coordination observed during performance in SSCGs. For this purpose we calculated positional data (GPS 15 Hz) from ten U-15 football players performing in three SSCGs varying in player numbers (3v3, 4v4 and 5v5). Key measures of SSCG system behaviours included values of (1) players' dispersion, (2) teams' separateness, (3) coupling strength and time delays between participants' emerging movements, respectively. Results showed that values of participants' dispersion increased, but the teams' separateness remained identical across treatments. Coupling strength and time delay also showed consistent values across SSCGs. These results exemplified how complex adaptive systems, like football teams, can harness inherent degeneracy to maintain similar team spatial-temporal relations with opponents through changes in inter-individual coordination modes (i.e., players' dispersion). The results imply that different team behaviours might emerge at different ratios of field dimension/player numbers. Therefore, sport pedagogists should carefully evaluate the effects of changing RSP in SSCGs as a way of promoting increased or decreased pressure on players.

Movement Demands of Elite Under-20s and Senior International Rugby Union Players

PubMed Central

Drawer, Scott; Pollard, Ben; Eager, Robin; Taylor, Neil; Cook, Christian J.

2016-01-01

This study compared the movement demands of elite international Under-20 age grade (U20s) and senior international rugby union players during competitive tournament match play. Forty elite professional players from an U20 and 27 elite professional senior players from international performance squads were monitored using 10Hz global positioning systems (GPS) during 15 (U20s) and 8 (senior) international tournament matches during the 2014 and 2015 seasons. Data on distances, velocities, accelerations, decelerations, high metabolic load (HML) distance and efforts, and number of sprints were derived. Data files from players who played over 60 min (n = 258) were separated firstly into Forwards and Backs, and more specifically into six positional groups; FR–Front Row (prop & hooker), SR–Second Row, BR–Back Row (Flankers & No.8), HB–Half Backs (scrum half & outside half), MF–Midfield (centres), B3 –Back Three (wings & full back) for match analysis. Linear mixed models revealed significant differences between U20 and senior teams in both the forwards and backs. In the forwards the seniors covered greater HML distance (736.4 ± 280.3 vs 701.3 ± 198.7m, p = 0.01) and severe decelerations (2.38 ± 2.2 vs 2.28 ± 1.65, p = 0.05) compared to the U20s, but performed less relative HSR (3.1 ± 1.6 vs 3.2 ± 1.5, p < 0.01), moderate (19.4 ± 10.5 vs 23.6 ± 10.5, p = 0.01) and high accelerations (2.2 ± 1.9 vs 4.3 ± 2.7, p < 0.01) and sprint•min-1 (0.11 ± 0.06 vs 0.11 ± 0.05, p < 0.01). Senior backs covered a greater relative distance (73.3 ± 8.1 vs 69.1 ± 7.6 m•min-1, p < 0.01), greater High Metabolic Load (HML) distance (1138.0 ± 233.5 vs 1060.4 ± 218.1m, p < 0.01), HML efforts (112.7 ± 22.2 vs 98.8 ± 21.7, p < 0.01) and heavy decelerations (9.9 ± 4.3 vs 9.5 ± 4.4, p = 0.04) than the U20s backs. However, the U20s backs performed more relative HSR (7.3 ± 2.1 vs 7.2 ± 2.1, p <0.01) and sprint•min-1 (0.26 ± 0.07 vs 0.25 ± 0.07, p < 0.01). Further investigation highlighted differences between the 6 positional groups of the teams. The positional groups that differed the most on the variables measured were the FR and MF groups, with the U20s FR having higher outputs on HSR, moderate & high accelerations, moderate, high & severe decelerations, HML distance, HML efforts, and sprints•min-1. For the MF group the senior players produced greater values for relative distance covered, HSR, moderate decelerations, HML distance and sprint•min-1. The BR position group was most similar with the only differences seen on heavy accelerations (U20s higher) and moderate decelerations (seniors higher). Findings demonstrate that U20s internationals appear to be an adequate ‘stepping stone’ for preparing players for movement characteristics found senior International rugby, however, the current study highlight for the first time that certain positional groups may require more time to be able to match the movement demands required at a higher playing level than others. Conditioning staff must also bear in mind that the U20s players whilst maintaining or improving match movement capabilities may require to gain substantial mass in some positions to match their senior counterparts. PMID:27824865

Movement Demands of Elite Under-20s and Senior International Rugby Union Players.

PubMed

Cunningham, Daniel J; Shearer, David A; Drawer, Scott; Pollard, Ben; Eager, Robin; Taylor, Neil; Cook, Christian J; Kilduff, Liam P

2016-01-01

This study compared the movement demands of elite international Under-20 age grade (U20s) and senior international rugby union players during competitive tournament match play. Forty elite professional players from an U20 and 27 elite professional senior players from international performance squads were monitored using 10Hz global positioning systems (GPS) during 15 (U20s) and 8 (senior) international tournament matches during the 2014 and 2015 seasons. Data on distances, velocities, accelerations, decelerations, high metabolic load (HML) distance and efforts, and number of sprints were derived. Data files from players who played over 60 min (n = 258) were separated firstly into Forwards and Backs, and more specifically into six positional groups; FR-Front Row (prop & hooker), SR-Second Row, BR-Back Row (Flankers & No.8), HB-Half Backs (scrum half & outside half), MF-Midfield (centres), B3 -Back Three (wings & full back) for match analysis. Linear mixed models revealed significant differences between U20 and senior teams in both the forwards and backs. In the forwards the seniors covered greater HML distance (736.4 ± 280.3 vs 701.3 ± 198.7m, p = 0.01) and severe decelerations (2.38 ± 2.2 vs 2.28 ± 1.65, p = 0.05) compared to the U20s, but performed less relative HSR (3.1 ± 1.6 vs 3.2 ± 1.5, p < 0.01), moderate (19.4 ± 10.5 vs 23.6 ± 10.5, p = 0.01) and high accelerations (2.2 ± 1.9 vs 4.3 ± 2.7, p < 0.01) and sprint•min-1 (0.11 ± 0.06 vs 0.11 ± 0.05, p < 0.01). Senior backs covered a greater relative distance (73.3 ± 8.1 vs 69.1 ± 7.6 m•min-1, p < 0.01), greater High Metabolic Load (HML) distance (1138.0 ± 233.5 vs 1060.4 ± 218.1m, p < 0.01), HML efforts (112.7 ± 22.2 vs 98.8 ± 21.7, p < 0.01) and heavy decelerations (9.9 ± 4.3 vs 9.5 ± 4.4, p = 0.04) than the U20s backs. However, the U20s backs performed more relative HSR (7.3 ± 2.1 vs 7.2 ± 2.1, p <0.01) and sprint•min-1 (0.26 ± 0.07 vs 0.25 ± 0.07, p < 0.01). Further investigation highlighted differences between the 6 positional groups of the teams. The positional groups that differed the most on the variables measured were the FR and MF groups, with the U20s FR having higher outputs on HSR, moderate & high accelerations, moderate, high & severe decelerations, HML distance, HML efforts, and sprints•min-1. For the MF group the senior players produced greater values for relative distance covered, HSR, moderate decelerations, HML distance and sprint•min-1. The BR position group was most similar with the only differences seen on heavy accelerations (U20s higher) and moderate decelerations (seniors higher). Findings demonstrate that U20s internationals appear to be an adequate 'stepping stone' for preparing players for movement characteristics found senior International rugby, however, the current study highlight for the first time that certain positional groups may require more time to be able to match the movement demands required at a higher playing level than others. Conditioning staff must also bear in mind that the U20s players whilst maintaining or improving match movement capabilities may require to gain substantial mass in some positions to match their senior counterparts.

Resting ECG findings in elite football players.

PubMed

Bohm, Philipp; Ditzel, Roman; Ditzel, Heribert; Urhausen, Axel; Meyer, Tim

2013-01-01

The purpose of the study was to evaluate ECG abnormalities in a large sample of elite football players. Data from 566 elite male football players (57 of them of African origin) above 16 years of age were screened retrospectively (age: 20.9 ± 5.3 years; BMI: 22.9 ± 1.7 kg · m(-2), training history: 13.8 ± 4.7 years). The resting ECGs were analysed and classified according to the most current ECG categorisation of the European Society of Cardiology (ESC) (2010) and a classification of Pelliccia et al. (2000) in order to assess the impact of the new ESC-approach. According to the classification of Pelliccia, 52.5% showed mildly abnormal ECG patterns and 12% were classified as distinctly abnormal ECG patterns. According to the classification of the ESC, 33.7% showed 'uncommon ECG patterns'. Short-QT interval was the most frequent ECG pattern in this group (41.9%), followed by a shortened PR-interval (19.9%). When assessed with a QTc cut-off-point of 340 ms (instead of 360 ms), only 22.2% would have had 'uncommon ECG patterns'. Resting ECG changes amongst elite football players are common. Adjustment of the ESC criteria by adapting proposed time limits for the ECG (e.g. QTc, PR) should further reduce the rate of false-positive results.

Motivational patterns as an instrument for predicting success in promising young football players.

PubMed

Zuber, Claudia; Zibung, Marc; Conzelmann, Achim

2015-01-01

Psychological characteristics are crucial to identifying talents, which is why these are being incorporated in today's multidimensional talent models. In addition to multidimensionality, talent studies are increasingly drawing on holistic theories of development, leading to the use of person-oriented approaches. The present study adopts such an approach by looking at the influence that motivational characteristics have on the development of performance, in a person-oriented way. For this purpose, it looks at how the constructs achievement motive, achievement goal orientation and self-determination interact with one another, what patterns they form and how these patterns are linked to subsequent sports success. Ninety-seven top young football players were questioned twice. Another year later, it was enquired which of these players had been selected for the U15 national team. At both measuring points, four patterns were identified, which displayed a high degree of structural and individual stability. As expected, the highly intrinsically achievement-oriented players were significantly more likely to move up into the U15 national team. The results point to the importance of favourable patterns of motivational variables in the form of specific types, for medium-term performance development among promising football talents, and thus provide valuable clues for the selection and promotion of those.

Self-concept in fairness and rule establishment during a competitive game: a computational approach

PubMed Central

Lee, Sang Ho; Kim, Sung-Phil; Cho, Yang Seok

2015-01-01

People consider fairness as well as their own interest when making decisions in economic games. The present study proposes a model that encompasses the self-concept determined by one's own kindness as a factor of fairness. To observe behavioral patterns that reflect self-concept and fairness, a chicken game experiment was conducted. Behavioral data demonstrates four distinct patterns; “switching,” “mutual rush,” “mutual avoidance,” and “unfair” patterns. Model estimation of chicken game data shows that a model with self-concept predicts those behaviors better than previous models of fairness, suggesting that self-concept indeed affects human behavior in competitive economic games. Moreover, a non-stationary parameter analysis revealed the process of reaching consensus between the players in a game. When the models were fitted to a continuous time window, the parameters of the players in a pair with “switching” and “mutual avoidance” patterns became similar as the game proceeded, suggesting that the players gradually formed a shared rule during the game. In contrast, the difference of parameters between the players in the “unfair” and “mutual rush” patterns did not become stable. The outcomes of the present study showed that people are likely to change their strategy until they reach a mutually beneficial status. PMID:26441707

Player Load, Acceleration, and Deceleration During Forty-Five Competitive Matches of Elite Soccer.

PubMed

Dalen, Terje; Ingebrigtsen, Jørgen; Ettema, Gertjan; Hjelde, Geir Havard; Wisløff, Ulrik

2016-02-01

The use of time-motion analysis has advanced our understanding of position-specific work rate profiles and the physical requirements of soccer players. Still, many of the typical soccer activities can be neglected, as these systems only examine activities measured by distance and speed variables. This study used triaxial accelerometer and time-motion analysis to obtain new knowledge about elite soccer players' match load. Furthermore, we determined acceleration/deceleration profiles of elite soccer players and their contribution to the players' match load. The data set includes every domestic home game (n = 45) covering 3 full seasons (2009, 2010, and 2011) for the participating team (Rosenborg FC), and includes 8 central defenders (n = 68), 9 fullbacks (n = 83), 9 central midfielders (n = 70), 7 wide midfielders (n = 39), and 5 attackers (A, n = 50). A novel finding was that accelerations contributed to 7-10% of the total player load for all player positions, whereas decelerations contributed to 5-7%. Furthermore, the results indicate that other activities besides the high-intensity movements contribute significantly to the players' total match workload. Therefore, motion analysis alone may underestimate player load because many high-intensity actions are without a change in location at the pitch or they are classified as low-speed activity according to current standards. This new knowledge may help coaches to better understand the different ways players achieve match load and could be used in developing individualized programs that better meet the "positional physical demands" in elite soccer.

Knowledge Representation of the Melody and Rhythm in Koto Songs

NASA Astrophysics Data System (ADS)

Deguchi, Sachiko; Shirai, Katsuhiko

This paper describes the knowledge representation of the melody and rhythm in koto songs based on the structure of the domain: the scale, melisma (the melody in a syllable), and bar. We have encoded koto scores and extracted 2,3,4-note melodic patterns sequentially from the voice part of koto scores. The 2,3,4-note patterns used in the melisma are limited and the percentages of top patterns are high. The 3,4-note melodic patterns are examined at each scale degree. These patterns are more restricted than the patterns that are possible under the constraint of the scale. These typical patterns on the scale represent the knowledge of koto players. We have analyzed rhythms in two different ways. We have extracted rhythms depending on each melodic pattern, while we have extracted rhythms depending on each bar. The former are complicated and the latter are typical. This result indicates that koto players recognize melodic patterns and rhythmic patterns independently. Our analyses show the melodic patterns and rhythmic patterns that are acquired by koto players. These patterns will be applied to the description of variations of the melisma to build a score database. These patterns will also be applied to a composition and education. The melodic patterns can be extracted from other genres of Japanese traditional music, foreign old folk songs or chants by using this method.

Genetics Home Reference: congenital mirror movement disorder

MedlinePlus

... Accessibility FOIA Viewers & Players U.S. Department of Health & Human Services National Institutes of Health National Library of Medicine Lister Hill National Center for Biomedical Communications 8600 Rockville Pike, Bethesda, MD 20894, USA HONCode ...

Small-sided games in team sports training: a brief review.

PubMed

Halouani, Jamel; Chtourou, Hamdi; Gabbett, Tim; Chaouachi, Anis; Chamari, Karim

2014-12-01

Small-sided games (SSGs) incorporating skills, sport-specific movements, at intensities sufficient to promote aerobic adaptations, are being increasingly implemented in professional team sport environments. Small-sided games are often employed by coaches based on the premise that the greatest training benefits occur when training simulates the specific movement patterns and physiological demands of the sport. At present, there is relatively little information regarding how SSG can best be used to improve physical capacities and technical and tactical skills in team sports. It is possible that with some modifications (e.g., number of players, pitch size, coach encouragement, and wrestling), such games may be physiologically beneficial for athletes with relatively high initial aerobic fitness levels. For instance, it has been shown that 3-a-side soccer SSG resulted in higher intensity (i.e., greater overall distance, less jogging and walking, higher heart rate, and more tackling, dribbling, goal attempts, and passes) than 5-a-side SSG. Likewise, when player numbers were kept constant, a larger playing area increased the intensity of the SSG with a smaller playing area having the opposite effect. It has also been demonstrated that energy expenditure was similar between badminton and volleyball courts, but lower than that obtained in a basketball court. Moreover, it has been demonstrated in rugby that wrestling can increase the physical demands of SSG. Consistent coach encouragement can also increase training intensity, although most rule changes have trivial or no effect on exercise intensity. Further research is required to examine the optimal periodization strategies of SSG training for the long-term development of physiological capacity, technical skill, and tactical proficiency, while also minimizing the associated risk of injuries.

Acute motor, neurocognitive and neurophysiological change following concussion injury in Australian amateur football. A prospective multimodal investigation.

PubMed

Pearce, Alan J; Hoy, Kate; Rogers, Mark A; Corp, Daniel T; Davies, Charlotte B; Maller, Jerome J; Fitzgerald, Paul B

2015-09-01

This multimodal study investigated the motor, neurocognitive and neurophysiological responses following a sports related concussion injury in the acute-phase (up to 10 days) in sub-elite Australian football players. Between-group, repeated measures. Over the course of one season (six months), 43 male players from one football club (25.1 ± 4.5 years) were assessed for fine motor dexterity, visuomotor reaction time, implicit learning and attention. Motor cortex excitability and inhibition were assessed using transcranial magnetic stimulation. Of the 43 players, eight suffered concussion injuries, and were compared to 15 non-concussed players (active control) who returned for follow up testing. Post-concussion assessments using the aforementioned tests were carried out at 48 and 96 h, and 10 days. Compared to the non-concussed players, those who suffered concussion showed slowed fine dexterity (P = 0.02), response (P = 0.02) and movement times (P = 0.01) 48 h post-concussion. Similarly, attentional performance was reduced in the concussed group at all time points (48 h: P < 0.01; 96 h: P < 0.01; and 10 days: P = 0.02) post-concussion. TMS revealed significantly increased corticospinal inhibition at 48 (P = 0.04) and 96 h post concussion (P = 0.02) with significant correlations between increased corticospinal inhibition and response (r = 0.48; P < 0.01), movement time (r = 0.42; P = 0.02), and attention performance (r = 0.44; P = 0.01). This study has demonstrated that acutely concussed Australian football players show abnormalities in motor, cognitive and neurophysiological measures with variable rates of recovery. These findings suggest that measuring the recovery of concussed athletes should incorporate a range of testing modalities rather than relying on one area of measurement in determining return to play. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Effects of Different Post-Activation Potentiation Warm-Ups on Repeated Sprint Ability in Soccer Players from Different Competitive Levels.

PubMed

Sanchez-Sanchez, Javier; Rodriguez, Alejandro; Petisco, Cristina; Ramirez-Campillo, Rodrigo; Martínez, Cristian; Nakamura, Fábio Y

2018-03-01

This study aimed to compare the effects of a traditional warm-up with two post-activation potentiation (PAP) warm-up strategies on the repeated sprint ability (RSA) of soccer players from national (NL) and regional (RL) competitive levels. Sixteen young players (NL, n = 8, age = 20.7 ± 1.4 y, body mass = 68.5 ± 7.0 kg, body height = 177.4 ± 5.2 cm; RL, n = 8, age = 20.8 ± 1.0 y, body mass = 68.7 ± 4.0 kg, body height = 176.6 ± 5.6 cm) were recruited to complete a traditional warm-up (CONTROL), a PAP warm-up incorporating squats with a load (~60% 1RM) that allowed a high speed (1 m/s) of movement and a high number of repetitions (PAP-1), and a PAP warm-up with a load (~90% 1RM) that allowed a moderate speed (0.5 m/s) of movement and a reduced number of repetitions (PAP-0.5). A RSA test (six 20-m sprints with 20 s of recovery) was performed 5 min after the PAP warm-up to assess the effects of the different protocols on the fastest sprint (RSAb) and the mean time of all sprints (RSAm). A meaningful improvement of RSA performance was observed with PAP-0.5, attaining a large effect on NL (RSAb, ES = -1.5; RSAm, ES = -1.3) and only a small effect on RL athletes (RSAb and RSAm, ES = -0.2). Moreover, when each RSA sprint performance was compared between NL and RL players, after PAP-0.5 greater performance for all sprints was observed in the NL players. Therefore, adding a heavy strength-based conditioning exercise during the warm-up prior to a RSA test may induce significant performance improvements in NL, but only small effects in RL players.

Effects of Different Post-Activation Potentiation Warm-Ups on Repeated Sprint Ability in Soccer Players from Different Competitive Levels

PubMed Central

Sanchez-Sanchez, Javier; Rodriguez, Alejandro; Petisco, Cristina; Ramirez-Campillo, Rodrigo; Martínez, Cristian; Nakamura, Fábio Y.

2018-01-01

Abstract This study aimed to compare the effects of a traditional warm-up with two post-activation potentiation (PAP) warm-up strategies on the repeated sprint ability (RSA) of soccer players from national (NL) and regional (RL) competitive levels. Sixteen young players (NL, n = 8, age = 20.7 ± 1.4 y, body mass = 68.5 ± 7.0 kg, body height = 177.4 ± 5.2 cm; RL, n = 8, age = 20.8 ± 1.0 y, body mass = 68.7 ± 4.0 kg, body height = 176.6 ± 5.6 cm) were recruited to complete a traditional warm-up (CONTROL), a PAP warm-up incorporating squats with a load (~60% 1RM) that allowed a high speed (1 m/s) of movement and a high number of repetitions (PAP-1), and a PAP warm-up with a load (~90% 1RM) that allowed a moderate speed (0.5 m/s) of movement and a reduced number of repetitions (PAP-0.5). A RSA test (six 20-m sprints with 20 s of recovery) was performed 5 min after the PAP warm-up to assess the effects of the different protocols on the fastest sprint (RSAb) and the mean time of all sprints (RSAm). A meaningful improvement of RSA performance was observed with PAP-0.5, attaining a large effect on NL (RSAb, ES = -1.5; RSAm, ES = -1.3) and only a small effect on RL athletes (RSAb and RSAm, ES = -0.2). Moreover, when each RSA sprint performance was compared between NL and RL players, after PAP-0.5 greater performance for all sprints was observed in the NL players. Therefore, adding a heavy strength-based conditioning exercise during the warm-up prior to a RSA test may induce significant performance improvements in NL, but only small effects in RL players. PMID:29599871

Somatotype variables related to strength and power output in male basketball players.

PubMed

Buśko, Krzysztof; Pastuszak, Anna; Lipińska, Monika; Lipińska, Marta; Gryko, Karol

2017-01-01

The purpose of this study was to investigate the relationship between somatotype, muscular strength, power output measured in maximal cycle ergometer exercise bouts, and maximal power output and height of rise of the body mass centre (jump height) measured in akimbo counter movement jump (ACMJ), counter movement jump (CMJ) and spike jump (SPJ), in male basketball players. Thirteen male basketball players (second division, age 19.4 ± 0.8 years, body height 192.9 ± 5.6 cm, body mass 88.8 ± 8.6 kg, training experience 9.3 ± 0.8 years) participated in the study. Somatotype was determined using the Heath-Carter method. Maximal joint torques were measured under static conditions. Power output was measured in 2 maximal cycle ergometer exercise bouts, 10 seconds each, with increasing external loads equal to 7.5 and 10.0% of the body weight (BW). All jump trials (ACMJ, CMJ and SPJ) were performed on a force plate. The mean somatotype of basketball players amounted to: 2.8-4.2-3.2. The sum of the joint torques for left and right lower extremities (0.613), trunk (0.631) and all six measured muscle groups (0.647) were significantly correlated (p < 0.05) with the mesomorphic component. Endomorphic, mesomorphic and ectomorphic components were correlated insignificantly with values of maximal power and height of jump during ACMJ, CMJ and SPJ trials. The power output measured in maximal cycle ergometer exercise bouts with increasing external loads was significantly correlated (p < 0.05) with mesomorphy and ectomorphy. It can be assumed that basketball players' anthropometric characteristics can influence their level of performance but it is not a decisive factor.

Biomotor structures in elite female handball players according to performance.

PubMed

Cavala, Marijana; Rogulj, Nenad; Srhoj, Vatromir; Srhoj, Ljerka; Katić, Ratko

2008-03-01

In order to identify biomotor structures in elite female handball players, factor structures of morphological characteristics and basic motor abilities, and of variables evaluating situation motor abilities of elite female handball players (n = 53) were determined first, followed by determination of differences and relations of the morphological, motor and specific motor space according to handball performance. Factor analysis of 16 morphological measures produced three morphological factors, i.e. factor of absolute voluminosity, i.e. mesoendomorphy, factor of longitudinal skeleton dimensionality, and factor of transverse hand dimensionality. Factor analysis of 15 motor variables yielded five basic motor dimensions, i.e. factor of agility, factor of throwing explosive strength, factor of running explosive strength (sprint), factor of jumping explosive strength and factor of movement frequency rate. Factor analysis of 5 situation motor variables produced two dimensions: factor of specific agility with explosiveness and factor of specific precision with ball manipulation. Analysis of variance yielded greatest differences relative to handball performance in the factor of specific agility and throwing strength, and the factor of basic motoricity that integrates the ability of coordination (agility) with upper extremity throwing explosiveness and lower extremity sprint (30-m sprint) and jumping (standing triple jump). Considering morphological factors, the factor of voluminosity, i.e. mesoendomorphy, which is defined by muscle mass rather than adipose tissue, was found to contribute significantly to the players'performance. Results of regression analysis indicated the handball performance to be predominantly determined by the general specific motor factor based on specific agility and explosiveness, and by the morphological factor based on body mass and volume, i.e. muscle mass. Concerning basic motor abilities, the factor of movement frequency rate, which is associated with the ability of ball manipulation, was observed to predict significantly the handball players' performance.

Anthropometric and physical performance characteristics of top-elite, elite and non-elite youth female team handball players.

PubMed

Moss, Samantha Louise; McWhannell, Nicola; Michalsik, Lars Bojsen; Twist, Craig

2015-01-01

In order to maximise the potential for success, developing nations need to produce superior systems to identify and develop talent, which requires comprehensive and up-to-date values on elite players. This study examined the anthropometric and physical characteristics of youth female team handball players (16.07 ± 1.30 years) in non-elite (n = 47), elite (n = 37) and top-elite players (n = 29). Anthropometric profiling included sum of eight skinfolds, body mass, stature, girths, breadths and somatotype. Performance tests included 20 m sprint, counter-movement jump, throwing velocity, repeated shuttle sprint and jump ability test, and Yo-Yo Intermittent Recovery Test Level 1. Youth top-elite players had greater body mass, lean mass, stature, limb girths and breadths than elite and non-elite players, while only stature and flexed arm were higher in elite compared to non-elite players (all P < 0.05). Sum of skinfolds and waist-to-hip ratio were similar between groups (P > 0.05). Top-elite performed better in most performance tests compared to both elite and non-elite players (P < 0.05), although maximal and repeated 10 m sprints were similar between playing standards (P > 0.05). Elite outperformed non-elite players only in throwing velocity. The findings reveal that non-elite players compare unfavourably to top-elite international European players in many anthropometric and performance characteristics, and differ in a few characteristics compared to elite European club team players. This study is useful for emerging team handball nations in improving talent identification processes.

A Force-Velocity Relationship and Coordination Patterns in Overarm Throwing

PubMed Central

van den Tillaar, Roland; Ettema, Gertjan

2004-01-01

A force-velocity relationship in overarm throwing was determined using ball weights varying from 0.2 to 0.8 kg. Seven experienced handball players were filmed at 240 frames per second. Velocity of joints of the upper extremity and ball together with the force on the ball were derived from the data. A statistically significant negative relationship between force and maximal ball velocity, as well as between ball weight and maximal ball velocity was observed. Also, with increase of ball weight the total throwing movement time increased. No significant change in relative timing of the different joints was demonstrated, suggesting that the subjects did not change their “global ”coordination pattern (kinematics) within the tested range of ball weights. A simple model revealed that 67% of ball velocity at ball release was explained by the summation of effects from the velocity of elbow extension and internal rotation of the shoulder. With regard to the upper extremity the internal rotation of the shoulder and elbow extension are two important contributors to the total ball velocity at release. Key Points An inverse relationship between load and velocity and a linear force-velocity exists in overarm throwing with ball weights varying from 0.2 to 0.8 kg. Qualitatively, no changes in coordination pattern (relative timing) occur with increasing ball weight within the tested range of ball weights. The absolute throwing movement time increased with ball weight. Quantitatively, with regard to the upper extremity, the internal rotation of the shoulder and elbow extension are two important contributors to the total ball velocity at release. PMID:24624005

Patterns of Gambling Activities and Gambling Problems Among Italian High School Students: Results from a Latent Class Analysis.

PubMed

De Luigi, Nicola; Gibertoni, Dino; Randon, Emanuela; Scorcu, Antonello E

2018-06-01

This study aims to provide an estimate of the prevalence of gambling among Italian adolescents and a description of their patterns of gambling activities (PGAs) using a latent class analysis on 13 different types of games. A nationwide sample of 10,959 Italian high school students was recruited in 2013. We assessed problem gambling using the South Oaks Gambling Screen: Revisited for Adolescent (SOGS-RA) scale. Approximately half (50.6%) of students reported gambling at least once in the previous year; 5.0% of them were problem gamblers and 9.1% were at-risk gamblers according to their SOGS-RA scores. Eight PGAs were identified, among which heavy players (1.7% of students) could be classified as problem gamblers and broad skill players (2.0%) and lotteries & sports players (2.4%) as "at-risk" players. These high-risk classes were consistently associated with risky behaviours in terms of substance use, school performance, money spent on gambling and family environment; the other five classes identified low-risk players associated with safe behaviours. To the best of our knowledge, this is the first study to identify PGAs among Italian adolescents. Problem gamblers are not a homogeneous group in terms of patterns of gambling activities and are associated with different risk factors, among which environmental factors, such as parents' gambling attitude and behaviour, deserve special attention. The acknowledgment of such patterns and risk factors could be useful in developing sensible public policies addressing prevention strategies and regulatory instruments.

Comparative analysis of gameplay and players emotion in the most popular games from play store

NASA Astrophysics Data System (ADS)

Riwinoto; Mahfud, N.; Lumombo, L.

2018-03-01

The development of the android mobile operating system and the presence of Play Store services poses challenges for developers to produce exciting mobile games. Although publishing games in Play Store is not difficult, in fact developers have to face tough competition to make homemade games can become popular. This study analyzes the gameplay of three popular paid-free games in Play Store that can survive for a period of one year from the top 10 positions in October 2015- November 2016. Analysis performed on 8 elements of the game based on the definition of Fullerton and emotional expression analysis of respondents who appeared while playing the three choosen games. The analysis shows that scarce resources are the main attraction of all three games because they create conflicts, giving constraints and challenges to players. The multiplayer game has a pattern of results and the result makes the opponent become more negative than the player to win. While the single player game is analyzed has a pattern to make the player get positive to win. There are 3 basic emotions that most often appear that is joy, disgust and surprise. Multiplayer games tend to emphasize the emotions of joy players, while single player games tend to bring disgust emotions.

Shoulder injuries in adolescent rugby players

PubMed Central

Hodhody, Ghazal; Mackenzie, Tanya A

2016-01-01

Background Rugby is a high-intensity contact sport, frequently causing shoulder injuries. Between the ages of 12 years to 18 years, academy and county level players are being selected for professional contracts, making this is a critical stage of their career. The present study aimed to describe the patterns of injury in adolescent rugby players with shoulder injuries. Methods Academy and county level rugby players in the target age group, over a 7-year period, were included in the present study. Data collected included the mechanism of injury, position and level of play, radiology and surgical findings, and recurrence rate at a minimum of 2 years post-surgery. Results One hundred and sixty-nine cases adhered to the inclusion criteria, with most cases involving two or more pathologies in the shoulder (54%). Forwards sustained more shoulder injuries than backs, incurring more labral injuries. By contrast, backs had a higher incidence of bony pathology. The mechanism of injury frequently correlated with player positions. There was a 21% injury recurrence rate, with forwards (7%) and higher level academy players (11%) most likely to suffer a recurrence. Conclusions Shoulder injury patterns in this important group of adolescent contact athletes are complex, with recurrence rates being higher than those in older rugby players. PMID:27583014

Split-Step Timing of Professional and Junior Tennis Players

PubMed Central

Leskosek, Bojan; Filipcic, Tjasa

2017-01-01

Abstract The purpose of the study was to determine the timing of a split-step in three categories of tennis players in four groups of strokes. Subjects were divided into three groups: male and female junior, and male professional tennis players. During two tournaments, all matches were recorded with two fixed video cameras. For every stroke, the timing of the split-step between the opponent’s impact point when hitting the ball and the player’s split-step was measured. A two-way analysis of variance (ANOVA) was used to determine the differences between groups of strokes, players and the interaction Player x Stroke Group. A Tukey post-hoc test was employed to determine specific differences. The results revealed differences between players in detecting the opponent’s movement, stroke and ball flight, which were reflected in different split-step timings. Each tennis player has his/her own timing mechanism which they adapt to various game situations. Response times differ significantly depending on the game situation. On average, they are the lowest in the serve, and then gradually rise from the return of the serve to baseline game, reaching the highest values in specific game situations. Players react faster in the first serve than in the second one and in the return of the serve, the response times are lower after the return of the second serve PMID:28210342

'Football is good for your sleep': favorable sleep patterns and psychological functioning of adolescent male intense football players compared to controls.

PubMed

Brand, Serge; Beck, Johannes; Gerber, Markus; Hatzinger, Martin; Holsboer-Trachsler, Edith

2009-11-01

It is commonly assumed that physical activity exerts a favorable impact on sleep, although scientific evidence is lacking. This study investigated the impact of football sports on the sleep patterns of 36 male chronic and intense football players and 34 controls. Participants completed a sleep log for seven consecutive days. Compared to controls, football players reported shorter sleep onset latency, fewer awakenings, higher scores of sleep quality and a lower variability of sleep from weekdays to weekends. The findings suggest that football sports activity is positively associated with both quantitative and qualitative dimensions of sleep.

Countermovement-Jump-Phase Characteristics of Senior and Academy Rugby League Players.

PubMed

McMahon, John J; Murphy, Shannon; Rej, Sophie J E; Comfort, Paul

2017-07-01

Gross measures of countermovement-jump (CMJ) performance are commonly used to track maturational changes in neuromuscular function in rugby league (RL). The purpose of this study was to conduct both a gross and a more detailed temporal-phase analysis of the CMJ performances of senior and academy RL players, to provide greater insight into how neuromuscular function differs between these groups. Twenty senior and 14 academy (under-19) male RL players performed 3 maximal-effort CMJs on a force platform, with forward dynamics subsequently employed to allow gross performance measures and entire kinetic- and kinematic-time curves to be compared between groups. Jump height (JH), reactive strength index modified, concentric displacement, and relative concentric impulse (C-IMP) were the only gross measures that were greater for senior players (d = 0.58-0.91) than for academy players. The relative force- and displacement-time curves were similar between groups, but the relative power- and velocity-time curves were greater (d = 0.59-0.97) for the senior players at 94-96% and 89-100% of the total movement time, respectively. The CMJ distinguished between senior and academy RL players, with seniors demonstrating greater JH through applying a larger C-IMP and thus achieving greater velocity throughout the majority of the concentric phase and at takeoff. Therefore, academy RL players should train to improve triple (ie, ankle, knee, and hip) extension velocity during the CMJ to bring their JH scores in line with those attained by senior players.

Eye movement accuracy determines natural interception strategies.

PubMed

Fooken, Jolande; Yeo, Sang-Hoon; Pai, Dinesh K; Spering, Miriam

2016-11-01

Eye movements aid visual perception and guide actions such as reaching or grasping. Most previous work on eye-hand coordination has focused on saccadic eye movements. Here we show that smooth pursuit eye movement accuracy strongly predicts both interception accuracy and the strategy used to intercept a moving object. We developed a naturalistic task in which participants (n = 42 varsity baseball players) intercepted a moving dot (a "2D fly ball") with their index finger in a designated "hit zone." Participants were instructed to track the ball with their eyes, but were only shown its initial launch (100-300 ms). Better smooth pursuit resulted in more accurate interceptions and determined the strategy used for interception, i.e., whether interception was early or late in the hit zone. Even though early and late interceptors showed equally accurate interceptions, they may have relied on distinct tactics: early interceptors used cognitive heuristics, whereas late interceptors' performance was best predicted by pursuit accuracy. Late interception may be beneficial in real-world tasks as it provides more time for decision and adjustment. Supporting this view, baseball players who were more senior were more likely to be late interceptors. Our findings suggest that interception strategies are optimally adapted to the proficiency of the pursuit system.

Effects of a 6-week junior tennis conditioning program on service velocity.

PubMed

Fernandez-Fernandez, Jaime; Ellenbecker, Todd; Sanz-Rivas, David; Ulbricht, Alexander; Ferrautia, Alexander

2013-01-01

This study examined the effects of a 6-week strength-training program on serve velocity in youth tennis players. Thirty competitive healthy and nationally ranked male junior tennis players (13 years of age) were randomly and equally divided into control and training groups. The training group performed 3 sessions (60-70 min) weekly for 6 weeks, comprising core strength, elastic resistance and medicine ball exercises. Both groups (control and training) also performed a supervised stretching routine at the end of each training session, during the 6 week intervention. Service velocity, service accuracy and shoulder internal/external rotation were assessed initially and at the end of the 6-week conditioning program for both, control and training groups. There was a significant improvement in the serve velocity for the training group (p = 0. 0001) after the intervention, whereas in the control group there were no differences between pre and post-tests (p = 0.29). Serve accuracy was not affected in the training group (p = 0.10), nor in the control group (p = 0.15). Shoulder internal/external rotation ROM significantly improved in both groups, training (p = 0.001) and control (p = 0.0001). The present results showed that a short- term training program for young tennis players, using minimum equipment and effort, can result in improved tennis performance (i.e., serve velocity) and a reduction in the risk of a possible overuse injury, reflected by an improvement in shoulder external/internal range of motion. Key PointsA short-term training program for young tennis players, using minimum equipment and effort, can result in improved tennis performance and a reduction in the risk of a possible overuse injury, reflected by an improvement in shoulder external/internal range of motionA combination of core stabilization, elastic resistance exercises, and upper body plyometric exercises (i.e., medicine ball throws), focussing on the primary muscle groups and stabilizers involved in tennis specific movement patterns, could be appropriate for development tennis playersStretching exercises are recommended in the cool-down phase following matches or training sessions.

Effects of A 6-Week Junior Tennis Conditioning Program on Service Velocity

PubMed Central

Fernandez-Fernandez, Jaime; Ellenbecker, Todd; Sanz-Rivas, david; Ulbricht, Alexander; Ferrautia, lexander

2013-01-01

This study examined the effects of a 6-week strength-training program on serve velocity in youth tennis players. Thirty competitive healthy and nationally ranked male junior tennis players (13 years of age) were randomly and equally divided into control and training groups. The training group performed 3 sessions (60-70 min) weekly for 6 weeks, comprising core strength, elastic resistance and medicine ball exercises. Both groups (control and training) also performed a supervised stretching routine at the end of each training session, during the 6 week intervention. Service velocity, service accuracy and shoulder internal/external rotation were assessed initially and at the end of the 6-week conditioning program for both, control and training groups. There was a significant improvement in the serve velocity for the training group (p = 0. 0001) after the intervention, whereas in the control group there were no differences between pre and post-tests (p = 0.29). Serve accuracy was not affected in the training group (p = 0.10), nor in the control group (p = 0.15). Shoulder internal/external rotation ROM significantly improved in both groups, training (p = 0.001) and control (p = 0.0001). The present results showed that a short- term training program for young tennis players, using minimum equipment and effort, can result in improved tennis performance (i.e., serve velocity) and a reduction in the risk of a possible overuse injury, reflected by an improvement in shoulder external/internal range of motion. Key Points A short-term training program for young tennis players, using minimum equipment and effort, can result in improved tennis performance and a reduction in the risk of a possible overuse injury, reflected by an improvement in shoulder external/internal range of motion A combination of core stabilization, elastic resistance exercises, and upper body plyometric exercises (i.e., medicine ball throws), focussing on the primary muscle groups and stabilizers involved in tennis specific movement patterns, could be appropriate for development tennis players Stretching exercises are recommended in the cool-down phase following matches or training sessions. PMID:24149801

Mental Rotation of Tactical Instruction Displays Affects Information Processing Demand and Execution Accuracy in Basketball.

PubMed

Koopmann, Till; Steggemann-Weinrich, Yvonne; Baumeister, Jochen; Krause, Daniel

2017-09-01

In sports games, coaches often use tactic boards to present tactical instructions during time-outs (e.g., 20 s to 60 s in basketball). Instructions should be presented in a way that enables fast and errorless information processing for the players. The aim of this study was to test the effect of different orientations of visual tactical displays on observation time and execution performance. High affordances in visual-spatial transformation (e.g., mental rotation processes) might impede information processing and might decrease execution performance with regard to the instructed playing patterns. In a within-subjects design with 1 factor, 10 novice students were instructed with visual tactical instructions of basketball playing patterns with different orientations either showing the playing pattern with low spatial disparity to the players' on-court perspective (basket on top) or upside down (basket on bottom). The self-chosen time for watching the pattern before execution was significantly shorter and spatial accuracy in pattern execution was significantly higher when the instructional perspective and the real perspective on the basketball court had a congruent orientation. The effects might be explained by interfering mental rotation processes that are necessary to transform the instructional perspective into the players' actual perspective while standing on the court or imagining themselves standing on the court. According to these results, coaches should align their tactic boards to their players' on-court viewing perspective.

Injury reporting rates and injury concealment patterns differ between high-school cirque performers and basketball players.

PubMed

Long, Ashley S; Ambegaonkar, Jatin P; Fahringer, Patty M

2011-12-01

The performing arts style of cirque has grown in popularity, with high-school participants increasingly practicing this style. Still, little research has examined the injury reporting rates and patterns in this population. Our study aimed to compare injury reporting rates and injury concealment patterns between high-school cirque performers and a peer-group of basketball players. Fifty participants (30 cirque, 20 basketball) completed a 12-item injury history and concealment instrument with chi-squared analyses and Fisher's exact tests comparing groups (p = 0.05). While no group differences (p = 0.36) existed in injuries reported, basketball players were more likely (p = 0.01) to miss participation due to injury than cirque performers. No significant difference existed between participants regarding which healthcare provider they reported to first (p = 0.27), but basketball players reported their injuries to the athletic trainer at higher rates (50%) than cirque performers (20%). A nonsignificant trend (p = 0.08) was noted in promptness to report injury, with more cirque performers (13%) concealing their injuries than basketball players (5%). Several reasons were noted for concealment of injury, with the most common being the belief that the injury would "go away" on its own. Knee injuries were most common in basketball players (23.7%) and back and knee injuries (10.5% each) in cirque performers. Despite similar injury rates, cirque participants concealed injuries more than peer-basketball players. Reasons may include losing performance roles, unfamiliarity and low trust with healthcare providers, ignorance about initially minor-looking injuries, and higher pain tolerance thresholds. Education and communication are essential to allow performing artists to seek healthcare support. Research is needed to appropriately understand and meet the needs of this underserved performing artist population.

Neuromuscular Taping Application in Counter Movement Jump: Biomechanical Insight in a Group of Healthy Basketball Players.

PubMed

Marcolin, Giuseppe; Buriani, Alessandro; Giacomelli, Andrea; Blow, David; Grigoletto, Davide; Gesi, Marco

2017-06-24

Kinesiologic elastic tape is widely used for both clinical and sport applications although its efficacy in enhancing agonistic performance is still controversial. Aim of the study was to verify in a group of healthy basketball players whether a neuromuscular taping application (NMT) on ankle and knee joints could affect the kinematic and the kinetic parameters of the jump, either by enhancing or inhibiting the functional performance. Fourteen healthy male basketball players without any ongoing pathologies at upper limbs, lower limbs and trunk volunteered in the study. They randomly performed 2 sets of 5 counter movement jumps (CMJ) with and without application of Kinesiologic tape. The best 3 jumps of each set were considered for the analysis. The Kinematics parameters analyzed were: knees maximal flexion and ankles maximal dorsiflexion during the push off phase, jump height and take off velocity. Vertical ground reaction force and maximal power expressed in the push off phase of the jump were also investigated. The NMT application in both knees and ankles showed no statistically significant differences in the kinematic and kinetic parameters and did not interfere with the CMJ performance. Bilateral NMT application in the group of healthy male basketball players did not change kinematics and kinetics jump parameters, thus suggesting that its routine use should have no negative effect on functional performance. Similarly, the combined application of the tape on both knees and ankles did not affect in either way jump performance.

Neuromuscular Taping Application in Counter Movement Jump: Biomechanical Insight in a Group of Healthy Basketball Players

PubMed Central

Marcolin, Giuseppe; Buriani, Alessandro; Giacomelli, Andrea; Blow, David; Grigoletto, Davide; Gesi, Marco

2017-01-01

Kinesiologic elastic tape is widely used for both clinical and sport applications although its efficacy in enhancing agonistic performance is still controversial. Aim of the study was to verify in a group of healthy basketball players whether a neuromuscular taping application (NMT) on ankle and knee joints could affect the kinematic and the kinetic parameters of the jump, either by enhancing or inhibiting the functional performance. Fourteen healthy male basketball players without any ongoing pathologies at upper limbs, lower limbs and trunk volunteered in the study. They randomly performed 2 sets of 5 counter movement jumps (CMJ) with and without application of Kinesiologic tape. The best 3 jumps of each set were considered for the analysis. The Kinematics parameters analyzed were: knees maximal flexion and ankles maximal dorsiflexion during the push off phase, jump height and take off velocity. Vertical ground reaction force and maximal power expressed in the push off phase of the jump were also investigated. The NMT application in both knees and ankles showed no statistically significant differences in the kinematic and kinetic parameters and did not interfere with the CMJ performance. Bilateral NMT application in the group of healthy male basketball players did not change kinematics and kinetics jump parameters, thus suggesting that its routine use should have no negative effect on functional performance. Similarly, the combined application of the tape on both knees and ankles did not affect in either way jump performance. PMID:28713536

Injuries in Little League Baseball from 1987 through 1996: Implications for Prevention.

ERIC Educational Resources Information Center

Mueller, Frederick O.; Marshall, Stephen W.; Kirby, Daniel P.

2001-01-01

Examined injury patterns in Little League baseball players over time, using insurance data from 17,221,210 players. Ball-related injuries were the most common. Batters had the greatest number of such injuries. One-quarter of the injuries were considered severe, and 13 players died. Though youth baseball appears to be very safe, there are areas…

Interracial Workplace Cooperation: Evidence from the NBA. NBER Working Paper No. 14749

ERIC Educational Resources Information Center

Price, Joseph; Lefgren, Lars; Tappen, Henry

2009-01-01

Using data from the National Basketball Association (NBA), we examine whether patterns of workplace cooperation occur disproportionately among workers of the same race. We find that, holding constant the composition of teammates on the floor, basketball players are no more likely to complete an assist to a player of the same race than a player of…

How Do Expert Soccer Players Encode Visual Information to Make Decisions in Simulated Game Situations?

ERIC Educational Resources Information Center

Poplu, Gerald; Ripoll, Hubert; Mavromatis, Sebastien; Baratgin, Jean

2008-01-01

The aim of this study was to determine what visual information expert soccer players encode when they are asked to make a decision. We used a repetition-priming paradigm to test the hypothesis that experts encode a soccer pattern's structure independently of the players' physical characteristics (i.e., posture and morphology). The participants…

The within-match patterns of locomotor efficiency during professional soccer match play: Implications for injury risk?

PubMed

Barrett, Steve; Midgley, Adrian; Reeves, Matt; Joel, Tom; Franklin, Ed; Heyworth, Rob; Garrett, Andrew; Lovell, Ric

2016-10-01

The principle aim of the current study was to examine within-match patterns of locomotor efficiency in professional soccer, determined as the ratio between tri-axial accelerometer data (PlayerLoad™) and locomotor activities. Between match variability and determinants of PlayerLoad™ during match play were also assessed. A single cohort, observational study. Tri-axial accelerometer data (PlayerLoad™) was recorded during 86 competitive soccer matches in 63 English championship players (574 match observations). Accelerometer data accumulated (PlayerLoad Vector Magnitude [PLVM]) from the individual-component planes of PlayerLoad™ (anterior-posterior PlayerLoad™ [PLAP], medial-lateral PlayerLoad™ [PLML] and vertical PlayerLoad™ [PLV]), together with locomotor activity (Total Distance Covered [TDC]) were determined in 15-min segments. Locomotor efficiency was calculated using the ratio of PLVM and TDC (PlayerLoad™ per metre). The proportion of variance explaining the within-match trends in PLVM, PLAP, APML, APv, and TDC was determined owing to matches, individual players, and positional role. PLVM, PLAP, APML, APv and TDC reduced after the initial 15-min match period (p=0.001; η(2)=0.22-0.43, large effects). PL:TDC increased in the last 15min of each half (p=0.001; η(2)=0.25, large effect). The variance in PLVM during soccer match-play was explained by individual players (63.9%; p=0.001) and between-match variation (21.6%; p=0.001), but not positional role (14.1%; p=0.364). Locomotor efficiency is lower during the latter stages of each half of competitive soccer match-play, a trend synonymous with observations of increased injury incidence and fatigue in these periods. Locomotor efficiency may be a valuable metric to identify fatigue and heightened injury risk during soccer training and match-play. Copyright © 2015 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

The effect of an early dismissal on player work-rate in a professional soccer match.

PubMed

Carling, Christopher; Bloomfield, Jonathan

2010-01-01

The aim of this study was to examine the effects of an early dismissal (after 5-min play) on work-rate in a professional soccer match. A computerised player tracking system was used to assess the work-rates of seven players who completed the match on a team with 10 players. A minute-by-minute analysis of the remaining 91min following the dismissal was performed for the total distance covered, the distance covered in five categories of movement intensity and the recovery time between high-intensity efforts for each player. The data were calculated for each half and for three equal intervals within each half and profiled against normative data for the same players obtained from the analysis of 15 games in the same season. Following the dismissal, the players covered a greater total distance than normal (p<0.025), particularly in moderate-intensity activities (p<0.01) and had shorter recovery times between high-intensity efforts (p<0.025). In contrast, there was a significant reduction between game halves for total distance covered at both the highest (p<0.025) and lowest running intensities (p<0.01). However, there were no differences in high-intensity activities across the three intervals in the second-half. These findings suggest that in 11 vs. 11, players may not always utilise their full physical potential as this match illustrated an increase in overall work-rate when reduced to 10 players. However, as a team with 10 players is likely to incur higher levels of fatigue, tactical alterations may be necessary and/or players may adopt a pacing strategy to endure the remainder of the match. Copyright (c) 2008 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

A Service Oriented Architecture for Robotic Platforms

DTIC Science & Technology

2011-03-01

Composite patternsidentify combinations of business and integration patterns such as those used in eCommerce applications, 4. Application patterns...systems and oers the same advantages and disadvantages of both layered and CORBA systems. 5One commercial CORBA implementation that the author is...complexity to users of the SOA and Player approaches. The advantage of the SOA approach over the Player approach is through the ESB concept in which we

Caffeine-containing energy drink improves physical performance of elite rugby players during a simulated match.

PubMed

Del Coso, Juan; Ramírez, Juan A; Muñoz, Gloria; Portillo, Javier; Gonzalez-Millán, Cristina; Muñoz, Víctor; Barbero-Álvarez, José C; Muñoz-Guerra, Jesús

2013-04-01

The purpose of this study was to investigate the effectiveness of a caffeine-containing energy drink in enhancing rugby players' physical performance during a simulated match. A second purpose was to determine the urinary caffeine excretion derived from the energy drink intake. In a randomized and counterbalanced order, 26 elite rugby players (mean ± SD for age and body mass, 25 ± 2 y and 93 ± 15 kg) played 2 simulated rugby games (2 × 30 min) 60 min after ingesting (i) 3 mg of caffeine per kilogram of body mass in the form of an energy drink (Fure, ProEnergetics) or (ii) the same drink without caffeine (placebo). During the matches, the individual running distance and the instantaneous speed were measured, and the number of running actions above 20 km·h(-1) (i.e., sprints) were determined, using global positioning system devices. The number of impacts above 5 g during the matches was determined by accelerometry. The ingestion of the energy drink, compared with the placebo, increased the total distance covered during the match (4749 ± 589 vs 5139 ± 475 m, p < 0.05), the running distance covered at more than 20 km·h(-1) (184 ± 38 vs 208 ± 38 m, p < 0.05), and the number of sprints (10 ± 7 vs 12 ± 7, p < 0.05). The ingestion of the energy drink also resulted in a greater overall number of impacts (481 ± 352 vs 641 ± 366, p < 0.05) and a higher postexercise urine caffeine concentration (0.1 ± 0.1 vs 2.4 ± 0.9 μg·mL(-1), p < 0.05). The use of an energy drink with a caffeine dose equivalent to 3 mg·kg(-1) considerably enhanced the movement patterns of rugby players during a simulated match.

Longitudinal Changes in Hip Strength and Range of Motion in Female Youth Soccer Players: Implications for ACL Injury, A Pilot Study.

PubMed

Nguyen, Anh-Dung; Zuk, Emma F; Baellow, Andrea L; Pfile, Kate R; DiStefano, Lindsay J; Boling, Michelle C

2017-09-01

Risk of anterior cruciate ligament (ACL) injuries in young female athletes increases with age, appearing to peak during maturation. Changes in hip muscle strength and range of motion (ROM) during this time may contribute to altered dynamic movement patterns that are known to increase risk of ACL injuries. Understanding the longitudinal changes in hip strength and ROM is needed to develop appropriate interventions to reduce the risk of ACL injuries. To examine the longitudinal changes in hip strength and ROM in female youth soccer players. Longitudinal descriptive study. Field setting. 14 female youth soccer athletes (14.1 ± 1.1 y, 165.8 ± 5.3 cm, 57.5 ± 9.9 kg) volunteered as part of a multiyear risk factor screening project. Clinical measures of hip strength and ROM were collected annually over 3 consecutive years. Passive hip internal rotation (IR), external rotation (ER), abduction (ABD), and adduction (ADD) ROM were measured with a digital inclinometer. Isometric hip ABD and extension (EXT) strength were evaluated using a hand-held dynamometer. Separate repeated-measures ANOVAs compared hip strength and ROM values across 3 consecutive years (P < .05). As youth female soccer players increased in age, there were no changes in normalized hip ABD (P = .830) or EXT strength (P = .062) across 3 consecutive years. Longitudinal changes in hip ROM were observed with increases in hip IR (P = .001) and ABD (P < .001), while hip ADD (P = .009) and ER (P < .001) decreased. Anatomical changes at the hip occur as youth female soccer players increase in age. While there are no changes in hip strength, there is an increase in hip IR and ABD ROM with a concomitant decrease in hip ER and ADD ROM. The resulting asymmetries in hip ROM may decrease the activation and force producing capabilities of the hip muscles during dynamic activities, contributing to altered lower extremity mechanics known to increase the risk of ACL injuries.

Electromyography variables during the golf swing: a literature review.

PubMed

Marta, Sérgio; Silva, Luís; Castro, Maria António; Pezarat-Correia, Pedro; Cabri, Jan

2012-12-01

The aim of the study was to review systematically the literature available on electromyographic (EMG) variables of the golf swing. From the 19 studies found, a high variety of EMG methodologies were reported. With respect to EMG intensity, the right erector spinae seems to be highly activated, especially during the acceleration phase, whereas the oblique abdominal muscles showed moderate to low levels of activation. The pectoralis major, subscapularis and latissimus dorsi muscles of both sides showed their peak activity during the acceleration phase. High muscle activity was found in the forearm muscles, especially in the wrist flexor muscles demonstrating activity levels above the maximal voluntary contraction. In the lower limb higher muscle activity of the trail side was found. There is no consensus on the influence of the golf club used on the neuromuscular patterns described. Furthermore, there is a lack of studies on average golf players, since most studies were executed on professional or low handicap golfers. Further EMG studies are needed, especially on lower limb muscles, to describe golf swing muscle activation patterns and to evaluate timing parameters to characterize neuromuscular patterns responsible for an efficient movement with lowest risk for injury. Copyright © 2012 Elsevier Ltd. All rights reserved.

The relative importance of different perceptual-cognitive skills during anticipation.

PubMed

North, Jamie S; Hope, Ed; Williams, A Mark

2016-10-01

We examined whether anticipation is underpinned by perceiving structured patterns or postural cues and whether the relative importance of these processes varied as a function of task constraints. Skilled and less-skilled soccer players completed anticipation paradigms in video-film and point light display (PLD) format. Skilled players anticipated more accurately regardless of display condition, indicating that both perception of structured patterns between players and postural cues contribute to anticipation. However, the Skill×Display interaction showed skilled players' advantage was enhanced in the video-film condition, suggesting that they make better use of postural cues when available during anticipation. We also examined anticipation as a function of proximity to the ball. When participants were near the ball, anticipation was more accurate for video-film than PLD clips, whereas when the ball was far away there was no difference between viewing conditions. Perceiving advance postural cues appears more important than structured patterns when the ball is closer to the observer, whereas the reverse is true when the ball is far away. Various perceptual-cognitive skills contribute to anticipation with the relative importance of perceiving structured patterns and advance postural cues being determined by task constraints and the availability of perceptual information. Copyright © 2016 Elsevier B.V. All rights reserved.

Evaluation of tactical training in team handball by means of artificial neural networks.

PubMed

Hassan, Amr; Schrapf, Norbert; Ramadan, Wael; Tilp, Markus

2017-04-01

While tactical performance in competition has been analysed extensively, the assessment of training processes of tactical behaviour has rather been neglected in the literature. Therefore, the purpose of this study is to provide a methodology to assess the acquisition and implementation of offensive tactical behaviour in team handball. The use of game analysis software combined with an artificial neural network (ANN) software enabled identifying tactical target patterns from high level junior players based on their positions during offensive actions. These patterns were then trained by an amateur junior handball team (n = 14, 17 (0.5) years)). Following 6 weeks of tactical training an exhibition game was performed where the players were advised to use the target patterns as often as possible. Subsequently, the position data of the game was analysed with an ANN. The test revealed that 58% of the played patterns could be related to the trained target patterns. The similarity between executed patterns and target patterns was assessed by calculating the mean distance between key positions of the players in the game and the target pattern which was 0.49 (0.20) m. In summary, the presented method appears to be a valid instrument to assess tactical training.

The fastest field sport in the world: A case report on 3-dimensional printed hurling gloves to help prevent injury.

PubMed

Harte, Daniel; Paterson, Abby

2017-10-28

Case series. Hand injuries are the most common injury observed in hurling although compliance in wearing protective gloves is reportedly low. To devise a glove that offers comfort, protection and freedom of movement, using the bespoke capabilities of 3-dimensional (3D) printing. Each player's "catching" hand was imaged using a 3D scanner to produce a bespoke glove that they later trialed and provided feedback. Nine players provided feedback. On average, the players favorably rated the glove for the protection offered. The average response on comfort was poor, and no players reported that glove aided performance during play. This feasibility study explores the versatility of 3D printing as a potential avenue to improve player compliance in wearing protective sportswear. Feedback will help refine glove design for future prototypes. Hurling is the primary focus in this study, but knowledge gains should be transferable to other sports that have a high incidence of hand injury. 4. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

Strong correlation of maximal squat strength with sprint performance and vertical jump height in elite soccer players

PubMed Central

Wisloff, U; Castagna, C; Helgerud, J; Jones, R; Hoff, J

2004-01-01

Background: A high level of strength is inherent in elite soccer play, but the relation between maximal strength and sprint and jumping performance has not been studied thoroughly. Objective: To determine whether maximal strength correlates with sprint and vertical jump height in elite male soccer players. Methods: Seventeen international male soccer players (mean (SD) age 25.8 (2.9) years, height 177.3 (4.1) cm, weight 76.5 (7.6) kg, and maximal oxygen uptake 65.7 (4.3) ml/kg/min) were tested for maximal strength in half squats and sprinting ability (0–30 m and 10 m shuttle run sprint) and vertical jumping height. Result: There was a strong correlation between maximal strength in half squats and sprint performance and jumping height. Conclusions: Maximal strength in half squats determines sprint performance and jumping height in high level soccer players. High squat strength did not imply reduced maximal oxygen consumption. Elite soccer players should focus on maximal strength training, with emphasis on maximal mobilisation of concentric movements, which may improve their sprinting and jumping performance. PMID:15155427

Injuries in male and female semi-professional football (soccer) players in Nigeria: prospective study of a National Tournament.

PubMed

Owoeye, Oluwatoyosi Babatunde Alex; Aiyegbusi, Ayoola Ibifubara; Fapojuwo, Oluwaseun Akinleye; Badru, Oluwaseun Abdulganiyu; Babalola, Anike Rasheedat

2017-03-21

Research on the epidemiology of football injuries in Africa is very sparse despite its importance for injury prevention planning in a continent with limited sports medicine resources. The vast majority of studies available in literature were conducted in Europe and only a very few studies have prospectively reported the pattern of football injury in Africa. The purpose of this study was to evaluate the incidence and pattern of injuries in a cohort of male and female semi-professional football players in Nigeria. A prospective cohort design was conducted, in which a total of 756 players with an age range of 18-32 years (356 males and 300 females) from 22 different teams (12 male and 10 female teams), were prospectively followed in a National Football Tournament. Physiotherapists recorded team exposure and injuries. Injuries were documented using the consensus protocol for data collection in studies relating to football injury surveillance. An overall incidence of 113.4 injuries/1000 h (95% CI 93.7-136.0) equivalent to 3.7 injuries/match and time-loss incidence of 15.6 injuries/1000 h were recorded for male players and 65.9 injuries/1000 h (95% CI 48.9-86.8) equivalent to 2.2 injuries/match and time-loss incidence of 7.9 injuries/1000 h were recorded for female players. Male players had a significantly higher risk of injuries [IRR = 1.72 (95% CI 1.23-2.45)]. Injuries mostly affected the lower extremity for both genders (n = 81, 70% and n = 31, 62% for males and females respectively). Lower leg contusion (n = 22, 19%) and knee sprain (n = 9, 18%) were the most common specific injury types for male and female players respectively. Most of the injuries were as a result of contact with another player (n = 102, 88%-males; n = 48, 96%-females). Time-loss injuries were mostly estimated as minimal (n = 11, 69%) for male players and severe (n = 4, 66%) for female players. The overall incidence of injuries among Nigerian semi-professional football players is high but most of the injuries do not result in time-loss. Pattern of injuries is mostly consistent with previous studies. More prospective studies are needed to establish injury prevention initiatives among African players.

Formative Evaluation of a Massively Multi-Player Persistent (MMP) Environment for Asymmetric Warfare Exercises

DTIC Science & Technology

2008-04-01

Initiative acknowledges the dearth of published research on Massively Multiplayer Online Games ((MMOGs), which are based on MMP technology) for...wanting help during the emergency, protesting insufficient aid being delivered in time, escalating to violence , including sniper attacks and attempted... multiplayer environment. The movement control systems were rated "moderately easy" to learn, and ease of movement after learning to use the controls was rated

Games for Social Change: Review of the Potential for Multi Player Online Gaming to Facilitate the Emergence and Growth of Progressive Movements for Social Change within Youth and Community Work

ERIC Educational Resources Information Center

Keating, Paul

2016-01-01

Building on the use of the internet and social media as sites for activism, this paper highlights the emergence of political activism and collective protest in the online gaming environment. Referencing social movement theory and the rapidly evolving capacity of multiplayer online games to facilitate the development of strong group identities and…

Event-based image recognition applied in tennis training assistance

NASA Astrophysics Data System (ADS)

Wawrzyniak, Zbigniew M.; Kowalski, Adam

2016-09-01

This paper presents a concept of a real-time system for individual tennis training assistance. The system is supposed to provide user (player) with information on his strokes accuracy as well as other training quality parameters such as velocity and rotation of the ball during its flight. The method is based on image processing methods equipped with developed explorative analysis of the events and their description by parameters of the movement. There has been presented the concept for further deployment to create a complete system that could assist tennis player during individual training.

Physiologically Modulating Videogames or Simulations which use Motion-Sensing Input Devices

NASA Technical Reports Server (NTRS)

Pope, Alan T. (Inventor); Stephens, Chad L. (Inventor); Blanson, Nina Marie (Inventor)

2014-01-01

New types of controllers allow players to make inputs to a video game or simulation by moving the entire controller itself. This capability is typically accomplished using a wireless input device having accelerometers, gyroscopes, and an infrared LED tracking camera. The present invention exploits these wireless motion-sensing technologies to modulate the player's movement inputs to the videogame based upon physiological signals. Such biofeedback-modulated video games train valuable mental skills beyond eye-hand coordination. These psychophysiological training technologies enhance personal improvement, not just the diversion, of the user.

Competing with lower level opponents decreases intra-team movement synchronization and time-motion demands during pre-season soccer matches.

PubMed

Folgado, Hugo; Duarte, Ricardo; Fernandes, Orlando; Sampaio, Jaime

2014-01-01

This study aimed to quantify the time-motion demands and intra-team movement synchronization during the pre-season matches of a professional soccer team according to the opposition level. Positional data from 20 players were captured during the first half of six pre-season matches of a Portuguese first league team. Time-motion demands were measured by the total distance covered and distance covered at different speed categories. Intra-team coordination was measured by calculating the relative phase of all pairs of outfield players. Afterwards, the percentage of time spent in the -30° to 30° bin (near-in-phase mode of coordination) was calculated for each dyad as a measure of space-time movement synchronization. Movement synchronization data were analyzed for the whole team, according to each dyad average speed and by groups of similar dyadic synchronization tendencies. Then, these data were compared according to the opponent team level (first league; second league; amateurs). Time-motion demands showed no differences in total distance covered per opposition levels, while matches opposing teams of superior level revealed more distance covered at very high intensity. Competing against superior level teams implied more time in synchronized behavior for the overall displacements and displacements at higher intensities. These findings suggest that playing against higher-level opponents (1st league teams) increased time-motion demands at high intensities in tandem with intra-team movement synchronization tendencies.

Morphological and motor characteristics of Croatian first league female football players.

PubMed

Jelaska, Petra Mandić; Katić, Ratko; Jelaska, Igor

2013-05-01

The aim of this study was to determine the structure of morphological and motor characteristics of Croatian first league female football players and their impact on the estimated quality of the players. According to the goal of the research, a sample consisted of 70 Croatian first league female football players. Participants were measured in 18 tests for assessing morphological characteristics, a set of 12 basic motor abilities tests and a set of 7 tests for assessing football-specific motor abilities. Exploratory factor analysis strategy was applied separately to all measured tests: morphological, basic motor abilities and football specific motor abilities. Factor analysis of morphological tests has shown existence of 3 significant latent dimensions that explain 64% of the total variability. Factors are defined as transverse dimensionality of the skeleton and voluminosity (35%), subcutaneous fat tissue (16%) and longitudinal dimensionality of the skeleton (13%). In the area of basic motor abilities, four factors were extracted. The first factor is responsible for the integration of agility and explosive power of legs, i.e. a factor of movement regulation (agility/lower body explosiveness) (23%), the second one defines muscle tone regulation (15%), the third one defines the frequency of leg movements (12%), while the fourth one is recognized as responsible for the manifestation of basic strength, particularly of basic core strength (19%). Two factors were isolated in the space of football-specific motor abilities: football-specific efficiency (53%) and situational football coordination (27%). Furthermore, by use of factor analysis on extracted latent dimensions (morphological, basic and football specific motor abilities) two higher order factors (explaining 87% of common variability) were extracted. They were named morphological-motor factor (54%) and football-specific motor abilities factor (33%). It is assumed that two extracted higher-order factors fully describe morphological and motor status of first league female football players. Furthermore, the linear regression results in latent space showed that the identified factors are very good predictors of female football players quality (delta = 0.959). In doing so, both specific motor abilities factors and the first factor of basic motor abilities as a factor of general motor efficiency have the greatest impact on player quality, and these factors have been identified as most important predictors of player quality in Croatian women's first league and elite female football players in general. Obtained results provide deep insight into the structure of relations between the morphological, motor and specific motor variables and also indicate the importance of such definition of specific motor abilities. Consequently, results explicitly indicate the necessity of early, continuous, and systematic development of football-specific motor abilities in female football players of high competitive level but also, adjusted, to the younger age categories.

The impact of elite labour migration on the identification, selection and development of European soccer players.

PubMed

Maguire, J; Pearton, R

2000-09-01

In this study, we examined sociocultural aspects of the identification, selection and development of elite soccer players as part of wider processes of globalization, particularly worker migration. Patterns of migration were identified among the 704 players who comprised the national squads of the 32 nations contesting the finals of the 1998 World Cup in France. An analysis of the migration patterns within and between the six Confederations into which member nations of FIFA are grouped established the European Federation (UEFA) as soccer's core economy. The study is subsequently focused on Europe and, in particular, upon the import strategies of clubs in the four most popular destination countries - England, Germany, Italy and Spain. It is argued that, in light of European Union deregulation of worker migration between member states and, in particular, the Bosman judgement, European soccer is being reshaped. The identification and selection of elite players are producing migrant patterns that are seen increasingly to impact upon indigenous player development and, potentially, the viability and success of national teams. We argue that, although these developments are contoured in part by global economic factors, economic accounts alone do not provide an adequate understanding of them. A series of interrelated economic, political, cultural and social factors is at work. We conclude with a brief outline of the policy implications of the analysis.

Analysis of male volleyball players' motor activities during a top level match.

PubMed

Mroczek, Dariusz; Januszkiewicz, Aleksander; Kawczyński, Adam S; Borysiuk, Zbigniew; Chmura, Jan

2014-08-01

The present study aims to assess motor activity of volleyball players using an original video recording method developed by the authors. Twenty-eight volleyball players taking part in 4 matches of the Polish Volleyball League were examined. The recorded data were analyzed in view of the mean total distance covered by volleyball players on different court positions during a match, set, and rally. The results showed that volleyball players cover the mean total distance of 1221 ± 327 m (mean ± SD) in a 3-set match, and 1757 ± 462 m in a 4-set match. A statistically significant difference (p ≤ 0.005) was found between the distance covered by the middle blockers and setters, defenders, spikers, and libero players in a match and in a set. The study revealed a tendency to lengthen the distance by the players in the final sets, which is indicative of the extended time of individual rallies. The mean distance covered in a single rally amounted to 10.92 ± 0.9 m in 4 matches (between 9.12 and 12.56 m). Considering the limited size of the field of play, volleyball players cover relatively long distances during a match and individual sets, with the shortest distance covered by middle blockers, and the longest by setters. From a practical application point of view, detailed topographic analysis of a player's movements on the court as well as precise data on the time of activity and rest breaks provide the coach with valuable information on the ways of development of arrhythmic, changing and dynamic training loads.

Mastery in Goal Scoring, T-Pattern Detection, and Polar Coordinate Analysis of Motor Skills Used by Lionel Messi and Cristiano Ronaldo

PubMed Central

Castañer, Marta; Barreira, Daniel; Camerino, Oleguer; Anguera, M. Teresa; Fernandes, Tiago; Hileno, Raúl

2017-01-01

Research in soccer has traditionally given more weight to players' technical and tactical skills, but few studies have analyzed the motor skills that underpin specific motor actions. The objective of this study was to investigate the style of play of the world's top soccer players, Cristiano Ronaldo and Lionel Messi, and how they use their motor skills in attacking actions that result in a goal. We used and improved the easy-to-use observation instrument (OSMOS-soccer player) with 9 criteria, each one expanded to build 50 categories. Associations between these categories were investigated by T-pattern detection and polar coordinate analysis. T-pattern analysis detects temporal structures of complex behavioral sequences composed of simpler or directly distinguishable events within specified observation periods (time point series). Polar coordinate analysis involves the application of a complex procedure to provide a vector map of interrelated behaviors obtained from prospective and retrospective sequential analysis. The T-patterns showed that for both players the combined criteria were mainly between the different aspects of motor skills, namely the use of lower limbs, contact with the ball using the outside of the foot, locomotion, body orientation with respect to the opponent goal line, and the criteria of technical actions and the right midfield. Polar coordinate analysis detected significant associations between the same criteria included in the T-patterns as well as the criteria of turning the body, numerical equality with no pressure, and relative numerical superiority. PMID:28553245

Mastery in Goal Scoring, T-Pattern Detection, and Polar Coordinate Analysis of Motor Skills Used by Lionel Messi and Cristiano Ronaldo.

PubMed

Castañer, Marta; Barreira, Daniel; Camerino, Oleguer; Anguera, M Teresa; Fernandes, Tiago; Hileno, Raúl

2017-01-01

Research in soccer has traditionally given more weight to players' technical and tactical skills, but few studies have analyzed the motor skills that underpin specific motor actions. The objective of this study was to investigate the style of play of the world's top soccer players, Cristiano Ronaldo and Lionel Messi, and how they use their motor skills in attacking actions that result in a goal. We used and improved the easy-to-use observation instrument (OSMOS-soccer player) with 9 criteria, each one expanded to build 50 categories. Associations between these categories were investigated by T-pattern detection and polar coordinate analysis. T-pattern analysis detects temporal structures of complex behavioral sequences composed of simpler or directly distinguishable events within specified observation periods (time point series). Polar coordinate analysis involves the application of a complex procedure to provide a vector map of interrelated behaviors obtained from prospective and retrospective sequential analysis. The T-patterns showed that for both players the combined criteria were mainly between the different aspects of motor skills, namely the use of lower limbs, contact with the ball using the outside of the foot, locomotion, body orientation with respect to the opponent goal line, and the criteria of technical actions and the right midfield. Polar coordinate analysis detected significant associations between the same criteria included in the T-patterns as well as the criteria of turning the body, numerical equality with no pressure, and relative numerical superiority.

The effect of model uncertainty on cooperation in sensorimotor interactions

PubMed Central

Grau-Moya, J.; Hez, E.; Pezzulo, G.; Braun, D. A.

2013-01-01

Decision-makers have been shown to rely on probabilistic models for perception and action. However, these models can be incorrect or partially wrong in which case the decision-maker has to cope with model uncertainty. Model uncertainty has recently also been shown to be an important determinant of sensorimotor behaviour in humans that can lead to risk-sensitive deviations from Bayes optimal behaviour towards worst-case or best-case outcomes. Here, we investigate the effect of model uncertainty on cooperation in sensorimotor interactions similar to the stag-hunt game, where players develop models about the other player and decide between a pay-off-dominant cooperative solution and a risk-dominant, non-cooperative solution. In simulations, we show that players who allow for optimistic deviations from their opponent model are much more likely to converge to cooperative outcomes. We also implemented this agent model in a virtual reality environment, and let human subjects play against a virtual player. In this game, subjects' pay-offs were experienced as forces opposing their movements. During the experiment, we manipulated the risk sensitivity of the computer player and observed human responses. We found not only that humans adaptively changed their level of cooperation depending on the risk sensitivity of the computer player but also that their initial play exhibited characteristic risk-sensitive biases. Our results suggest that model uncertainty is an important determinant of cooperation in two-player sensorimotor interactions. PMID:23945266

A biomechanical investigation of right-forward lunging step among badminton players.

PubMed

Mei, Qichang; Gu, Yaodong; Fu, Fengqin; Fernandez, Justin

2017-03-01

This study presents the kinematics and plantar pressure characteristics of eight elite national-level badminton athletes and eight recreational college-level badminton players while performing a right-forward lunge movement in a laboratory-simulated badminton court. The hypothesis was that recreational players would be significantly different from elite players in kinematics and plantar pressure measures. Vicon ® motion capture and Novel ® insole plantar pressure measurement were simultaneously taken to record the lower extremity kinematics and foot loading during stance. Recreational players showed significantly higher peak pressure in the lateral forefoot (P = 0.002) and force time integral in the lateral forefoot (P = 0.013) and other toes (P = 0.005). Elite athletes showed higher peak pressure in the medial forefoot (P = 0.003), hallux (P = 0.037) and force time integral in the medial forefoot (P = 0.009). The difference in landing techniques for the lunge step between elite athletes and recreational players was observed with peak ankle eversion (-38.2°±2.4° for athletes and -11.1°±3.9° for players, P = 0.015); smaller knee range of motion in the coronal and transverse planes, with differences in peak knee adduction (28.9°±6.8° for athletes and 15.7°±6.2° for players, P = 0.031); peak knee internal rotation (20.3°±1.3° for athletes and 11.8°±3.2° for players, P = 0.029) and peak hip flexion (77.3°±4.1° for athletes and 91.3°±9.3° for players, P = 0.037).

Identifying individuality and variability in team tactics by means of statistical shape analysis and multilayer perceptrons.

PubMed

Jäger, Jörg M; Schöllhorn, Wolfgang I

2012-04-01

Offensive and defensive systems of play represent important aspects of team sports. They include the players' positions at certain situations during a match, i.e., when players have to be on specific positions on the court. Patterns of play emerge based on the formations of the players on the court. Recognition of these patterns is important to react adequately and to adjust own strategies to the opponent. Furthermore, the ability to apply variable patterns of play seems to be promising since they make it harder for the opponent to adjust. The purpose of this study is to identify different team tactical patterns in volleyball and to analyze differences in variability. Overall 120 standard situations of six national teams in women's volleyball are analyzed during a world championship tournament. Twenty situations from each national team are chosen, including the base defence position (start configuration) and the two players block with middle back deep (end configuration). The shapes of the defence formations at the start and end configurations during the defence of each national team as well as the variability of these defence formations are statistically analyzed. Furthermore these shapes data are used to train multilayer perceptrons in order to test whether artificial neural networks can recognize the teams by their tactical patterns. Results show significant differences between the national teams in both the base defence position at the start and the two players block with middle back deep at the end of the standard defence situation. Furthermore, the national teams show significant differences in variability of the defence systems and start-positions are more variable than the end-positions. Multilayer perceptrons are able to recognize the teams at an average of 98.5%. It is concluded that defence systems in team sports are highly individual at a competitive level and variable even in standard situations. Artificial neural networks can be used to recognize teams by the shapes of the players' configurations. These findings support the concept that tactics and strategy have to be adapted for the team and need to be flexible in order to be successful. Copyright © 2010 Elsevier B.V. All rights reserved.

The test-retest reliability and criterion validity of a high-intensity, netball-specific circuit test: The Net-Test.

PubMed

Mungovan, Sean F; Peralta, Paula J; Gass, Gregory C; Scanlan, Aaron T

2018-04-12

To examine the test-retest reliability and criterion validity of a high-intensity, netball-specific fitness test. Repeated measures, within-subject design. Eighteen female netball players competing in an international competition completed a trial of the Net-Test, which consists of 14 timed netball-specific movements. Players also completed a series of netball-relevant criterion fitness tests. Ten players completed an additional Net-Test trial one week later to assess test-retest reliability using intraclass correlation coefficient (ICC), typical error of measurement (TEM), and coefficient of variation (CV). The typical error of estimate expressed as CV and Pearson correlations were calculated between each criterion test and Net-Test performance to assess criterion validity. Five movements during the Net-Test displayed moderate ICC (0.84-0.90) and two movements displayed high ICC (0.91-0.93). Seven movements and heart rate taken during the Net-Test held low CV (<5%) with values ranging from 1.7 to 9.5% across measures. Total time (41.63±2.05s) during the Net-Test possessed low CV and significant (p<0.05) correlations with 10m sprint time (1.98±0.12s; CV=4.4%, r=0.72), 20m sprint time (3.38±0.19s; CV=3.9%, r=0.79), 505 Change-of-Direction time (2.47±0.08s; CV=2.0%, r=0.80); and maximum oxygen uptake (46.59±2.58 mLkg -1 min -1 ; CV=4.5%, r=-0.66). The Net-Test possesses acceptable reliability for the assessment of netball fitness. Further, the high criterion validity for the Net-Test suggests a range of important netball-specific fitness elements are assessed in combination. Copyright © 2018 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Incidence and pattern of injuries among adolescent basketball players in Nigeria

PubMed Central

2012-01-01

Background Basketball is the second most popular sport in Nigeria after football and is commonly played by adolescents. Prospective studies on adolescent basketball players in Nigeria are lacking. Such studies will help to develop injury counter-measures. Hence, this study aimed at determining the incidence and pattern of injuries among adolescent basketball players in Nigeria. Methods A prospective observational study involving 141 adolescent basketball players (75 boys and 66 girls; with age range 15 – 18 years) who participated in the 2010 National Finals of the Nigeria Nestlé Milo Basketball Competition. Basketball-related injury data were collected by an assessor during the competition using a standardized basketball injury report form. Data were analyzed using descriptive and inferential statistics. Results A total of 32 injuries were recorded with an incidence of 22.7 injuries per 100 participants same for boys and girls. This is equivalent to 1.1 injury per match for boys and 0.9 injuries per match for girls. Jumping/landing was the most common cause of injury (28.1%, N = 9). Most of the injuries were at the lower extremities (75%, N = 24); with majority at the knee joint (40.6%, N = 13). Ligament sprain was the most common types of injury. The pattern of injuries among boys did not significantly differ from that of girls (P > 0.05). Most injuries (N = 13, 41%) occurred in the offensive half of the court and cryotherapy was the most frequently used treatment modality. Conclusion The overall incidence of match injury among adolescent amateur basketball players during a national competition in Nigeria was 22.7 injuries per 100 participants; equivalence of 1.0 injury per match. The pattern of injuries was similar in both genders and consistent with what has been previously reported in literature for adolescent basketball players. Exercise-based injury prevention programmes aimed at improving core strength and neuromuscular control at the lower limbs may help reduce the incidence of injuries. PMID:22559878

Incidence and pattern of injuries among adolescent basketball players in Nigeria.

PubMed

Owoeye, Oluwatoyosi Babatunde Alex; Akodu, Ashiyat Kehinde; Oladokun, Bayonle Matt; Akinbo, Sunday Rufus Akinwumi

2012-05-04

Basketball is the second most popular sport in Nigeria after football and is commonly played by adolescents. Prospective studies on adolescent basketball players in Nigeria are lacking. Such studies will help to develop injury counter-measures. Hence, this study aimed at determining the incidence and pattern of injuries among adolescent basketball players in Nigeria. A prospective observational study involving 141 adolescent basketball players (75 boys and 66 girls; with age range 15 - 18 years) who participated in the 2010 National Finals of the Nigeria Nestlé Milo Basketball Competition. Basketball-related injury data were collected by an assessor during the competition using a standardized basketball injury report form. Data were analyzed using descriptive and inferential statistics. A total of 32 injuries were recorded with an incidence of 22.7 injuries per 100 participants same for boys and girls. This is equivalent to 1.1 injury per match for boys and 0.9 injuries per match for girls. Jumping/landing was the most common cause of injury (28.1%, N = 9). Most of the injuries were at the lower extremities (75%, N = 24); with majority at the knee joint (40.6%, N = 13). Ligament sprain was the most common types of injury. The pattern of injuries among boys did not significantly differ from that of girls (P > 0.05). Most injuries (N = 13, 41%) occurred in the offensive half of the court and cryotherapy was the most frequently used treatment modality. The overall incidence of match injury among adolescent amateur basketball players during a national competition in Nigeria was 22.7 injuries per 100 participants; equivalence of 1.0 injury per match. The pattern of injuries was similar in both genders and consistent with what has been previously reported in literature for adolescent basketball players. Exercise-based injury prevention programmes aimed at improving core strength and neuromuscular control at the lower limbs may help reduce the incidence of injuries.

Historical Patterns and Variation in Treatment of Injuries in NFL (National Football League) Players and NCAA (National Collegiate Athletic Association) Division I Football Players.

PubMed

McCarty, Eric C; Kraeutler, Matthew J; Langner, Paula; Cook, Shane; Ellis, Byron; Godfrey, Jenna M

We conducted a study to identify and contrast patterns in the treatment of common injuries that occur in National Football League (NFL) players and National Collegiate Athletic Association (NCAA) Division I football players. Orthopedic team physicians for all 32 NFL and 119 NCAA Division I football teams were asked to complete a survey regarding demographics and preferred treatment of a variety of injuries encountered in football players. Responses were received from 31 (97%) of the 32 NFL and 111 (93%) of the 119 NCAA team physicians. Although patellar tendon autograft was the preferred graft choice for both groups of team physicians, the percentage of NCAA physicians who allowed return to football 6 months or less after anterior cruciate ligament reconstruction was significantly (P = .03) higher than that of NFL physicians. Prophylactic knee bracing, which may prevent medial collateral ligament injuries, was used at a significantly (P < .0001) higher rate by NCAA teams (89%) than by NFL teams (28%). Ketorolac injections were given by a significantly (P < .01) higher percentage of NFL teams (93%) than of NCAA teams (62%). Understanding the current trends in the management of these injuries is beneficial in designing studies that may help improve the treatment and prevention of injuries in football players.

The mechanisms and boundary conditions of the Einstellung effect in chess: evidence from eye movements.

PubMed

Sheridan, Heather; Reingold, Eyal M

2013-01-01

In a wide range of problem-solving settings, the presence of a familiar solution can block the discovery of better solutions (i.e., the Einstellung effect). To investigate this effect, we monitored the eye movements of expert and novice chess players while they solved chess problems that contained a familiar move (i.e., the Einstellung move), as well as an optimal move that was located in a different region of the board. When the Einstellung move was an advantageous (but suboptimal) move, both the expert and novice chess players who chose the Einstellung move continued to look at this move throughout the trial, whereas the subset of expert players who chose the optimal move were able to gradually disengage their attention from the Einstellung move. However, when the Einstellung move was a blunder, all of the experts and the majority of the novices were able to avoid selecting the Einstellung move, and both the experts and novices gradually disengaged their attention from the Einstellung move. These findings shed light on the boundary conditions of the Einstellung effect, and provide convergent evidence for Bilalić, McLeod, & Gobet (2008)'s conclusion that the Einstellung effect operates by biasing attention towards problem features that are associated with the familiar solution rather than the optimal solution.

Comparing performance and kinematics of throwing with a circular and whip-like wind up by experienced handball players.

PubMed

van den Tillaar, R; Zondag, A; Cabri, J

2013-12-01

The aim of this study was to compare the performance (throwing velocity of the ball) and kinematics of overarm throwing with the circular and whip-like wind up in elite handball players. Twenty-two elite handball players (11 men and 11 women) conducted both types of throws. The ball release velocity, maximal ball acceleration, maximal velocity of the end points of the five segments and maximal angles, angles at ball release and maximal angular velocities of the 11 joint movements and their timing during the throw were analyzed. Significantly higher ball release velocities (21.9 m/s vs 20.6 m/s) were reached together with higher maximal linear velocities of the end points of all segments and longer throwing time with the circular wind up than with the whip-like wind up. Furthermore, it seems that the timing and amount of maximal angular pelvis rotation was the main contributor to the difference in the maximal ball release velocity between the two wind ups. The findings support the observation that overarm throwing with the circular wind up results in higher ball releases but also a longer throwing movement in comparison to whip-like wind up throws. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Musical instruments of Brazilian capoeira: Historical roots, symbolism, and use

NASA Astrophysics Data System (ADS)

Ilari, Beatriz

2002-11-01

This paper describes the historical roots, symbolism, and uses of musical instruments in capoeira. A martial art form of Afro-Brazilian origin, capoeira is rhythmically performed to music in a roda (i.e., circle). Capoeira is at times defined as a martial art form disguised as dance because it is rooted in the struggles of African slaves. Elements of music, dance, fight, and ritual are part of this unique martial art form, which has two main styles: Angola and Regional. Capoeira styles are important as they determine rhythmic patterns, chant, movement, and musical instrumentation in a roda. The leading instrument in all capoeira styles is the berimbau. The instrument dictates the rhythm and movement of capoeira players in a roda (Ilari, 2001). Made out of a wooden stick, a wire, and a gourd and played with a stick and a coin, the berimbau is considered a sacred instrument due to its association with the cry of the slaves. Other instruments used in capoeira are pandeiros, agogo bells, reco-recos, and atabaques. A discussion regarding the use of these instruments within the context of capoeira will be presented at the conference. The incorporation of these instruments into contemporary Brazilian music will also be considered.

Speed and agility of 12- and 14-year-old elite male basketball players.

PubMed

Jakovljevic, Sasa T; Karalejic, Milivoje S; Pajic, Zoran B; Macura, Marija M; Erculj, Frane F

2012-09-01

The aims of this study were (a) to identify and compare the speed and agility of 12- and 14-year-old elite male basketball players and (b) to investigate relations between speed and agility for both age groups of basketball players, to help coaches to improve their work. Sixty-four players aged 12 (M = 11.98 years, SD = 0.311) and 54 players aged 14 (M = 14.092 years, SD = 0.275) were tested. Three agility tests: agility t-test, zigzag agility drill, and agility run 4 × 15 m and 3 speed tests: 20-m run, 30-m run, and 50-m run were applied. Fourteen-year-old players achieved significantly better results in all speed and agility tests compared with 12-year-old players. The correlation coefficient (r = 0.81, p = 0.001) showed that 12-year-old players have the same ability in the 30- and 50-m runs. The other correlation coefficient (r = 0.59, p = 0.001) indicated that 20- and 30-m runs had inherently different qualities. The correlation coefficients between agility tests were <0.71, and therefore, each test in this group represents a specific task. In 14-year-old players, the correlation coefficients between the speed test results were <0.71. In contrast, the correlation coefficients between the agility tests were >0.71, which means that all the 3 tests represent the same quality. During the speed training of 12-year-old players, it is advisable to focus on shorter running distances, up to 30 m. During the agility training of the same players, it is useful to apply exercises with various complexities. In speed training of the 14-year-old players, the 30- and 50-m runs should be applied, and agility training should include more specific basketball movements and activities.

Match analysis and player characteristics in rugby sevens.

PubMed

Ross, Alex; Gill, Nicholas; Cronin, John

2014-03-01

Rugby sevens is a contact sport contested by two teams of seven players who compete over two 7-min halves, most frequently played in a tournament style. The IRB Sevens World Series is thought of as the preeminent rugby sevens competition in the world and has grown in competitiveness from its inception in 2000. The decision to include rugby sevens in the 2016 Olympics is likely to increase the global profile and participation in the game. Many rugby sevens players concurrently compete in 15-a-side rugby union as backs and loose forwards; however, a continued increase in the popularity of rugby sevens will likely see the emergence of the specialist rugby sevens player. Often thought of as the abbreviated version of rugby union, rugby sevens is played under nearly identical laws and on the same field dimensions as the 15-man code. However, research has shown the movement demands of rugby sevens and rugby union are dissimilar, with rugby sevens players spending a larger proportion of the game running at high intensity (≥ 5 m s(-1)). Given the dissimilarity in match demands in conjunction with differences in the competition structure between the codes, it appears the considerable depth of literature specific to performance in rugby union may be of little value for the preparation of rugby sevens players. Investigations of the physical characteristics of rugby sevens players show backs are lighter and shorter than forwards, while players across all positions possess a lean body composition. International rugby sevens players have similar speed characteristics to rugby union backs across distances of 10-30 m; however, rugby sevens players appear to have superior intermittent aerobic endurance. Despite being of likely importance, little is known of the strength and power characteristics of rugby sevens players. Research into the speed and aerobic endurance characteristics of rugby sevens players has not distinguished between backs and forwards and, as such, it is unclear whether differences exist between the position groups.

The Musculoskeletal Readiness Screening Tool-Injury Predictor for United States Military Academy Preparatory Cadets

DTIC Science & Technology

2015-10-30

predictors of ACL injury.25 189 Several studies investigate the effects of faulty movement and injury 190 prediction for the lower extremity. In 2006...at 40% and 39% of the total injuries, respectively.16 In 2012, 83 193 NCAA Division I football players participated in a survey to assess low back...recent study , firefighters performed the FMS™ and firefighter-specific testing. Two 218 of the musculoskeletal movement variables were predictive of

Enhancing the learning of sport skills through external-focus feedback.

PubMed

Wulf, Gabriele; McConnel, Nathan; Gärtner, Matthias; Schwarz, Andreas

2002-06-01

The authors examined how the effectiveness of feedback for the learning of complex motor skills is affected by the focus of attention it induces. The feedback referred specifically either to body movements (internal focus) or to movement effects (external focus). In Experiment 1, groups of novices and advanced volleyball players (N = 48) practiced "tennis" serves under internal-focus or external-focus feedback conditions in a 2 (expertise) x 2 (feedback type) design. Type of feedback did not differentially affect movement quality, but external-focus feedback resulted in greater accuracy of the serves than internal-focus feedback during both practice and retention, independent of the level of expertise. In Experiment 2, the effects of relative feedback frequency as a function of attentional focus were examined. A 2 (feedback frequency: 100% vs. 33%) x 2 (feedback type) design was used. Experienced soccer players (N = 52) were required to shoot lofted passes at a target. External-focus feedback resulted in greater accuracy than internal-focus feedback did. In addition, reduced feedback frequency was beneficial under internal-focus feedback conditions, whereas 100% and 33% feedback were equally effective under external-focus conditions. The results demonstrate the effectiveness of effect-related, as opposed to movement-related, feedback and also suggest that there is a need to revise current views regarding the role of feedback for motor learning.

Utilization of Practice Session Average Inertial Load to Quantify College Football Injury Risk.

PubMed

Wilkerson, Gary B; Gupta, Ashish; Allen, Jeff R; Keith, Clay M; Colston, Marisa A

2016-09-01

Wilkerson, GB, Gupta, A, Allen, JR, Keith, CM, and Colston, MA. Utilization of practice session average inertial load to quantify college football injury risk. J Strength Cond Res 30(9): 2369-2374, 2016-Relatively few studies have investigated the potential injury prevention value of data derived from recently developed wearable technology for measurement of body mass accelerations during the performance of sport-related activities. The available evidence has been derived from studies focused on avoidance of overtraining syndrome, which is believed to induce a chronically fatigued state that can be identified through monitoring of inertial load accumulation. Reduced variability in movement patterns is also believed to be an important injury risk factor, but no evidence currently exists to guide interpretation of data derived from inertial measurement units (IMUs) in this regard. We retrospectively analyzed archived data for a cohort of 45 National Collegiate Athletic Association Division 1-football bowl subdivision football players who wore IMUs on the upper back during practice sessions to quantify any associations between average inertial load measured during practice sessions and occurrence of musculoskeletal sprains and strains. Both the coefficient of variation for average inertial load and frequent exposure to game conditions were found to be strongly associated with injury occurrence. Having either or both of the 2 risk factors provided strong discrimination between injured and noninjured players (χ = 9.048; p = 0.004; odds ratio = 8.04; 90% CI: 2.39, 27.03). Our findings may facilitate identification of individual football players who are likely to derive the greatest benefit from training activities designed to reduce injury risk through improved adaptability to rapidly changing environmental demands.

Video analysis of concussion injury mechanism in under-18 rugby

PubMed Central

Hendricks, Sharief; O'Connor, Sam; Lambert, Michael; Brown, James C; Burger, Nicholas; Mc Fie, Sarah; Readhead, Clint; Viljoen, Wayne

2016-01-01

Background Understanding the mechanism of injury is necessary for the development of effective injury prevention strategies. Video analysis of injuries provides valuable information on the playing situation and athlete-movement patterns, which can be used to formulate these strategies. Therefore, we conducted a video analysis of the mechanism of concussion injury in junior-level rugby union and compared it with a representative and matched non-injury sample. Methods Injury reports for 18 concussion events were collected from the 2011 to 2013 under-18 Craven Week tournaments. Also, video footage was recorded for all 3 years. On the basis of the injury events, a representative ‘control’ sample of matched non-injury events in the same players was identified. The video footage, which had been recorded at each tournament, was then retrospectively analysed and coded. 10 injury events (5 tackle, 4 ruck, 1 aerial collision) and 83 non-injury events were analysed. Results All concussions were a result of contact with an opponent and 60% of players were unaware of the impending contact. For the measurement of head position on contact, 43% had a ‘down’ position, 29% the ‘up and forward’ and 29% the ‘away’ position (n=7). The speed of the injured tackler was observed as ‘slow’ in 60% of injurious tackles (n=5). In 3 of the 4 rucks in which injury occurred (75%), the concussed player was acting defensively either in the capacity of ‘support’ (n=2) or as the ‘jackal’ (n=1). Conclusions Training interventions aimed at improving peripheral vision, strengthening of the cervical muscles, targeted conditioning programmes to reduce the effects of fatigue, and emphasising safe and effective playing techniques have the potential to reduce the risk of sustaining a concussion injury. PMID:27900149

An Expressive Bodily Movement Repertoire for Marimba Performance, Revealed through Observers' Laban Effort-Shape Analyses, and Allied Musical Features: Two Case Studies

PubMed Central

Broughton, Mary C.; Davidson, Jane W.

2016-01-01

Musicians' expressive bodily movements can influence observers' perception of performance. Furthermore, individual differences in observers' music and motor expertise can shape how they perceive and respond to music performance. However, few studies have investigated the bodily movements that different observers of music performance perceive as expressive, in order to understand how they might relate to the music being produced, and the particular instrument type. In this paper, we focus on marimba performance through two case studies—one solo and one collaborative context. This study aims to investigate the existence of a core repertoire of marimba performance expressive bodily movements, identify key music-related features associated with the core repertoire, and explore how observers' perception of expressive bodily movements might vary according to individual differences in their music and motor expertise. Of the six professional musicians who observed and analyzed the marimba performances, three were percussionists and experienced marimba players. Following training, observers implemented the Laban effort-shape movement analysis system to analyze marimba players' bodily movements that they perceived as expressive in audio-visual recordings of performance. Observations that were agreed by all participants as being the same type of action at the same location in the performance recording were examined in each case study, then across the two studies. A small repertoire of bodily movements emerged that the observers perceived as being expressive. Movements were primarily allied to elements of the music structure, technique, and expressive interpretation, however, these elements appeared to be interactive. A type of body sway movement and more localized sound generating actions were perceived as expressive. These movements co-occurred and also appeared separately. Individual participant data revealed slightly more variety in the types and locations of actions observed, with judges revealing preferences for observing particular types of expressive bodily movements. The particular expressive bodily movements that are produced and perceived in marimba performance appear to be shaped by music-related and sound generating features, musical context, and observer music and motor expertise. With an understanding of bodily movements that are generated and perceived as expressive, embodied music performance training programs might be developed to enhance expressive performer-audience communication. PMID:27630585

An Expressive Bodily Movement Repertoire for Marimba Performance, Revealed through Observers' Laban Effort-Shape Analyses, and Allied Musical Features: Two Case Studies.

PubMed

Broughton, Mary C; Davidson, Jane W

2016-01-01

Musicians' expressive bodily movements can influence observers' perception of performance. Furthermore, individual differences in observers' music and motor expertise can shape how they perceive and respond to music performance. However, few studies have investigated the bodily movements that different observers of music performance perceive as expressive, in order to understand how they might relate to the music being produced, and the particular instrument type. In this paper, we focus on marimba performance through two case studies-one solo and one collaborative context. This study aims to investigate the existence of a core repertoire of marimba performance expressive bodily movements, identify key music-related features associated with the core repertoire, and explore how observers' perception of expressive bodily movements might vary according to individual differences in their music and motor expertise. Of the six professional musicians who observed and analyzed the marimba performances, three were percussionists and experienced marimba players. Following training, observers implemented the Laban effort-shape movement analysis system to analyze marimba players' bodily movements that they perceived as expressive in audio-visual recordings of performance. Observations that were agreed by all participants as being the same type of action at the same location in the performance recording were examined in each case study, then across the two studies. A small repertoire of bodily movements emerged that the observers perceived as being expressive. Movements were primarily allied to elements of the music structure, technique, and expressive interpretation, however, these elements appeared to be interactive. A type of body sway movement and more localized sound generating actions were perceived as expressive. These movements co-occurred and also appeared separately. Individual participant data revealed slightly more variety in the types and locations of actions observed, with judges revealing preferences for observing particular types of expressive bodily movements. The particular expressive bodily movements that are produced and perceived in marimba performance appear to be shaped by music-related and sound generating features, musical context, and observer music and motor expertise. With an understanding of bodily movements that are generated and perceived as expressive, embodied music performance training programs might be developed to enhance expressive performer-audience communication.

Eccentric-Overload Training in Team-Sport Functional Performance: Constant Bilateral Vertical Versus Variable Unilateral Multidirectional Movements.

PubMed

Gonzalo-Skok, Oliver; Tous-Fajardo, Julio; Valero-Campo, Carlos; Berzosa, César; Bataller, Ana Vanessa; Arjol-Serrano, José Luis; Moras, Gerard; Mendez-Villanueva, Alberto

2017-08-01

To analyze the effects of 2 different eccentric-overload training (EOT) programs, using a rotational conical pulley, on functional performance in team-sport players. A traditional movement paradigm (ie, squat) including several sets of 1 bilateral and vertical movement was compared with a novel paradigm including a different exercise in each set of unilateral and multi-directional movements. Forty-eight amateur or semiprofessional team-sport players were randomly assigned to an EOT program including either the same bilateral vertical (CBV, n = 24) movement (squat) or different unilateral multidirectional (VUMD, n = 24) movements. Training programs consisted of 6 sets of 1 exercise (CBV) or 1 set of 6 exercises (VUMD) × 6-10 repetitions with 3 min of passive recovery between sets and exercises, biweekly for 8 wk. Functional-performance assessment included several change-of-direction (COD) tests, a 25-m linear-sprint test, unilateral multidirectional jumping tests (ie, lateral, horizontal, and vertical), and a bilateral vertical-jump test. Within-group analysis showed substantial improvements in all tests in both groups, with VUMD showing more robust adaptations in pooled COD tests and lateral/horizontal jumping, whereas the opposite occurred in CBV respecting linear sprinting and vertical jumping. Between-groups analyses showed substantially better results in lateral jumps (ES = 0.21), left-leg horizontal jump (ES = 0.35), and 10-m COD with right leg (ES = 0.42) in VUMD than in CBV. In contrast, left-leg countermovement jump (ES = 0.26) was possibly better in CBV than in VUMD. Eight weeks of EOT induced substantial improvements in functional-performance tests, although the force-vector application may play a key role to develop different and specific functional adaptations.

Sleep patterns and match performance in elite Australian basketball athletes.

PubMed

Staunton, Craig; Gordon, Brett; Custovic, Edhem; Stanger, Jonathan; Kingsley, Michael

2017-08-01

To assess sleep patterns and associations between sleep and match performance in elite Australian female basketball players. Prospective cohort study. Seventeen elite female basketball players were monitored across two consecutive in-season competitions (30 weeks). Total sleep time and sleep efficiency were determined using triaxial accelerometers for Baseline, Pre-match, Match-day and Post-match timings. Match performance was determined using the basketball efficiency statistic (EFF). The effects of match schedule (Regular versus Double-Header; Home versus Away) and sleep on EFF were assessed. The Double-Header condition changed the pattern of sleep when compared with the Regular condition (F (3,48) =3.763, P=0.017), where total sleep time Post-match was 11% less for Double-Header (mean±SD; 7.2±1.4h) compared with Regular (8.0±1.3h; P=0.007). Total sleep time for Double-Header was greater Pre-match (8.2±1.7h) compared with Baseline (7.1±1.6h; P=0.022) and Match-day (7.3±1.5h; P=0.007). Small correlations existed between sleep metrics at Pre-match and EFF for pooled data (r=-0.39 to -0.22; P≥0.238). Relationships between total sleep time and EFF ranged from moderate negative to large positive correlations for individual players (r=-0.37 to 0.62) and reached significance for one player (r=0.60; P=0.025). Match schedule can affect the sleep patterns of elite female basketball players. A large degree of inter-individual variability existed in the relationship between sleep and match performance; nevertheless, sleep monitoring might assist in the optimisation of performance for some athletes. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Musculoskeletal injuries among Malaysian badminton players.

PubMed

Shariff, A H; George, J; Ramlan, A A

2009-11-01

The purpose of this study was to investigate the pattern of musculoskeletal injuries sustained by Malaysian badminton players. This is a retrospective case notes review of all badminton players who attended the National Sports Institute (NSI) Clinic, Kuala Lumpur, Malaysia, and were diagnosed with musculoskeletal injuries. In a two and a half year period, from January 2005 to June 2007, 469 musculoskeletal injuries were diagnosed among badminton players at the NSI Clinic. The mean age of the players who attended the clinic was 19.2 (range 13-52) years. Approximately 60 percent of the injuries occurred in players younger than 20 years of age. The majority of injuries (91.5 percent) were categorised as mild overuse injury and mostly involved the knee. The majority of the injuries sustained by badminton players in this study were due to overuse, primarily in the knee. The majority of the injuries were diagnosed in younger players and occurred during training/practice sessions. There was no difference in terms of incidence and types of injuries between the genders.

Effects of knowing the task duration on players' pacing patterns during soccer small-sided games.

PubMed

Ferraz, Ricardo; Gonçalves, Bruno; Van Den Tillaar, Roland; Jiménez Sáiz, Sergio; Sampaio, Jaime; Marques, Mário C

2018-01-01

The aim of this study was to identify the influence of prior knowledge of exercise duration on players' pacing patterns during soccer small-sided games. Twenty semi-professional male soccer players participated in this study. In the first game scenario, players were not informed how long they would be required to play the small-sided game and the activity was terminated after 20 min (Unknown Condition). In the second game scenario, players were told that they would play the small-sided game for 10 min, but immediately after completing the 10-min game, they were asked to complete another 10 min (Partially Condition). In the third game scenario, players were instructed that they would play the small-sided game for 20 min and then they completed the 20-min game (Known Condition). The results presented a tendency of higher values in all performance variables in the [0'-10'] min compared with the [10'-20'] min. As the players' previous knowledge about the tasks duration increased, the performance between two moments tended to be similar. Considering the entire 20-min game duration, the Partially Condition of the exercise was the most demanding condition. In conclusion, the knowledge of shorter durations of the exercise seems to lead to an increase of exercise duration demand, and longer exercise durations possibly tend to decrease differences between full knowledge and not knowing the exercise duration.

Dynamics of tactical behaviour in association football when manipulating players' space of interaction.

PubMed

Ric, Angel; Torrents, Carlota; Gonçalves, Bruno; Torres-Ronda, Lorena; Sampaio, Jaime; Hristovski, Robert

2017-01-01

The analysis of positional data in association football allows the spatial distribution of players during matches to be described in order to improve the understanding of tactical-related constraints on the behavioural dynamics of players. The aim of this study was to identify how players' spatial restrictions affected the exploratory tactical behaviour and constrained the perceptual-motor workspace of players in possession of the ball, as well as inter-player passing interactions. Nineteen professional outfield male players were divided into two teams of 10 and 9 players, respectively. The game was played under three spatial constraints: a) players were not allowed to move out of their allocated zones, except for the player in possession of the ball; b) players were allowed to move to an adjacent zone, and; c) non-specific spatial constraints. Positional data was captured using a 5 Hz interpolated GPS tracking system and used to define the configuration states of players for each second in time. The configuration state comprised 37 categories derived from tactical actions, distance from the nearest opponent, distance from the target and movement speed. Notational analysis of players in possession of the ball allowed the mean time of ball possession and the probabilities of passing the ball between players to be calculated. The results revealed that the players' long-term exploratory behaviour decreased and their short-term exploration increased when restricting their space of interaction. Relaxing players' positional constraints seemed to increase the speed of ball flow dynamics. Allowing players to move to an adjacent sub-area increased the probabilities of interaction with the full-back during play build-up. The instability of the coordinative state defined by being free from opponents when players had the ball possession was an invariant feature under all three task constraints. By allowing players to move to adjacent sub-areas, the coordinative state became highly unstable when the distance from the target decreased. Ball location relative to the scoring zone and interpersonal distance constitute key environmental information that constrains the players' coordinative behaviour. Based on our results, dynamic overlap is presented as a good option to capture tactical performance. Moreover, the selected collective (i.e. relational) variables would allow coaches to identify the effects of training drills on teams and players' behaviour. More research is needed considering these type variables to understand how the manipulation of constraints induce a more stable or flexible dynamical structure of tactical behaviour.

Do running speed and shoe cushioning influence impact loading and tibial shock in basketball players?

PubMed Central

Liebenberg, Jacobus; Woo, Jeonghyun; Park, Sang-Kyoon; Yoon, Suk-Hoon; Cheung, Roy Tsz-Hei; Ryu, Jiseon

2018-01-01

Background Tibial stress fracture (TSF) is a common injury in basketball players. This condition has been associated with high tibial shock and impact loading, which can be affected by running speed, footwear condition, and footstrike pattern. However, these relationships were established in runners but not in basketball players, with very little research done on impact loading and speed. Hence, this study compared tibial shock, impact loading, and foot strike pattern in basketball players running at different speeds with different shoe cushioning properties/performances. Methods Eighteen male collegiate basketball players performed straight running trials with different shoe cushioning (regular-, better-, and best-cushioning) and running speed conditions (3.0 m/s vs. 6.0 m/s) on a flat instrumented runway. Tri-axial accelerometer, force plate and motion capture system were used to determine tibial accelerations, vertical ground reaction forces and footstrike patterns in each condition, respectively. Comfort perception was indicated on a 150 mm Visual Analogue Scale. A 2 (speed) × 3 (footwear) repeated measures ANOVA was used to examine the main effects of shoe cushioning and running speeds. Results Greater tibial shock (P < 0.001; η2 = 0.80) and impact loading (P < 0.001; η2 = 0.73–0.87) were experienced at faster running speeds. Interestingly, shoes with regular-cushioning or best-cushioning resulted in greater tibial shock (P = 0.03; η2 = 0.39) and impact loading (P = 0.03; η2 = 0.38–0.68) than shoes with better-cushioning. Basketball players continued using a rearfoot strike during running, regardless of running speed and footwear cushioning conditions (P > 0.14; η2 = 0.13). Discussion There may be an optimal band of shoe cushioning for better protection against TSF. These findings may provide insights to formulate rehabilitation protocols for basketball players who are recovering from TSF. PMID:29770274

The female player does not exist: gender identity relates to differences in player motivations and play styles.

PubMed

Poels, Karolien; De Cock, Nele; Malliet, Steven

2012-11-01

This study addresses the female player of massively multiplayer online (role-playing) games and investigates how gender identity (GI), indicating a person's identification with characteristics that are traditionally defined as masculine or feminine, can be used to explain playing patterns within the female gender group. Results from an online survey (n=466) show that females' player motivations and play styles vary as a function of their GI, indicating that it is a relevant and additional predictor of play behavior and confirming that female play behavior cannot be generalized based on stereotypical male/female conceptions.

Reciprocity on the Hardwood: Passing Patterns among Professional Basketball Players

PubMed Central

Willer, Robb; Sharkey, Amanda; Frey, Seth

2012-01-01

Past theory and research view reciprocal resource sharing as a fundamental building block of human societies. Most studies of reciprocity dynamics have focused on trading among individuals in laboratory settings. But if motivations to engage in these patterns of resource sharing are powerful, then we should observe forms of reciprocity even in highly structured group environments in which reciprocity does not clearly serve individual or group interests. To this end, we investigated whether patterns of reciprocity might emerge among teammates in professional basketball games. Using data from logs of National Basketball Association (NBA) games of the 2008–9 season, we estimated a series of conditional logistic regression models to test the impact of different factors on the probability that a given player would assist another player in scoring a basket. Our analysis found evidence for a direct reciprocity effect in which players who had “received” assists in the past tended to subsequently reciprocate their benefactors. Further, this tendency was time-dependent, with the probability of repayment highest soon after receiving an assist and declining as game time passed. We found no evidence for generalized reciprocity – a tendency to “pay forward” assists – and only very limited evidence for indirect reciprocity – a tendency to reward players who had sent others many assists. These findings highlight the power of reciprocity to shape human behavior, even in a setting characterized by extensive planning, division of labor, quick decision-making, and a focus on inter-group competition. PMID:23236354

Reciprocity on the hardwood: passing patterns among professional basketball players.

PubMed

Willer, Robb; Sharkey, Amanda; Frey, Seth

2012-01-01

Past theory and research view reciprocal resource sharing as a fundamental building block of human societies. Most studies of reciprocity dynamics have focused on trading among individuals in laboratory settings. But if motivations to engage in these patterns of resource sharing are powerful, then we should observe forms of reciprocity even in highly structured group environments in which reciprocity does not clearly serve individual or group interests. To this end, we investigated whether patterns of reciprocity might emerge among teammates in professional basketball games. Using data from logs of National Basketball Association (NBA) games of the 2008-9 season, we estimated a series of conditional logistic regression models to test the impact of different factors on the probability that a given player would assist another player in scoring a basket. Our analysis found evidence for a direct reciprocity effect in which players who had "received" assists in the past tended to subsequently reciprocate their benefactors. Further, this tendency was time-dependent, with the probability of repayment highest soon after receiving an assist and declining as game time passed. We found no evidence for generalized reciprocity - a tendency to "pay forward" assists - and only very limited evidence for indirect reciprocity - a tendency to reward players who had sent others many assists. These findings highlight the power of reciprocity to shape human behavior, even in a setting characterized by extensive planning, division of labor, quick decision-making, and a focus on inter-group competition.

Relative Age Effects in Women's Rugby Union From Developmental Leagues to World Cup Tournaments.

PubMed

Lemez, Srdjan; MacMahon, Clare; Weir, Patricia

2016-01-01

Annual age cohort groupings promote relative age effects (RAEs), which often, inadvertently, create participation and attainment biases between relatively older and younger players within the same age cohort. In a globally evolving sport, women's rugby team selection practices may potentially bypass qualified players as a result of maturational differences. Our study examined the prevalence of RAEs in women's rugby union. Player data (age range = 4-21+ years) were gathered from the 2006 and 2010 Rugby World Cups (n = 498) and from Canadian (n = 1,497) and New Zealand (NZ; n = 13,899) developmental rugby leagues. Although no evidence of an RAE was found in the World Cup samples, chi-square analyses identified some typical and atypical patterns of RAEs at the developmental levels (w ≥ .3). Younger developmental groups displayed a typical RAE patterning with a greater representation of older players (Canadian 13-year-olds, w = .58; NZ 4-year-olds, w = .35), whereas older developmental groups displayed an atypical RAE patterning with a greater representation of younger players (Canadian 19-year-olds, w = .58; NZ 17-year-olds, w = .32). Further, a traditional RAE emerged in the Canadian 11- to 15-year-old age group, χ2(3) = 10.92, p < .05, w = .30. The lack of homogeneity of traditional RAEs across the sample questions the existence of a single, clear RAE in women's rugby. Some evidence of participation inequalities at the developmental levels suggests that further RAE research in more varied sociocultural contexts may be necessary.

The physical characteristics of match-play in English schoolboy and academy rugby union.

PubMed

Read, Dale B; Jones, Ben; Phibbs, Padraic J; Roe, Gregory A B; Darrall-Jones, Joshua; Weakley, Jonathon J S; Till, Kevin

2018-03-01

The aim was to compare the physical characteristics of under-18 academy and schoolboy rugby union competition by position (forwards and backs). Using a microsensor unit, match characteristics were recorded in 66 players. Locomotor characteristics were assessed by maximum sprint speed (MSS) and total, walking, jogging, striding and sprinting distances. The slow component (<2 m · s -1 ) of PlayerLoad TM (PL slow ), which is the accumulated accelerations from the three axes of movement, was analysed as a measure of low-speed activity (e.g., rucking). A linear mixed-model was assessed with magnitude-based inferences. Academy forwards and backs almost certainly and very likely covered greater total distance than school forwards and backs. Academy players from both positions were also very likely to cover greater jogging distances. Academy backs were very likely to accumulate greater PL slow and the academy forwards a likely greater sprinting distance than school players in their respective positions. The MSS, total, walking and sprinting distances were greater in backs (likely-almost certainly), while forwards accumulated greater PL slow (almost certainly) and jogging distance (very likely). The results suggest that academy-standard rugby better prepares players to progress to senior competition compared to schoolboy rugby.

Expertise in complex decision making: the role of search in chess 70 years after de Groot.

PubMed

Connors, Michael H; Burns, Bruce D; Campitelli, Guillermo

2011-01-01

One of the most influential studies in all expertise research is de Groot's (1946) study of chess players, which suggested that pattern recognition, rather than search, was the key determinant of expertise. Many changes have occurred in the chess world since de Groot's study, leading some authors to argue that the cognitive mechanisms underlying expertise have also changed. We decided to replicate de Groot's study to empirically test these claims and to examine whether the trends in the data have changed over time. Six Grandmasters, five International Masters, six Experts, and five Class A players completed the think-aloud procedure for two chess positions. Findings indicate that Grandmasters and International Masters search more quickly than Experts and Class A players, and that both groups today search substantially faster than players in previous studies. The findings, however, support de Groot's overall conclusions and are consistent with predictions made by pattern recognition models. Copyright © 2011 Cognitive Science Society, Inc.

The immediate effect of lumbar spine patterns of neuromuscular joint facilitation in young amateur baseball players.

PubMed

Huo, Ming; Maruyama, Hitoshi; Kaneko, Takasumi; Naito, Daiki; Koiso, Yuta

2013-12-01

[Purpose] The aim of the study was to investigate the changes in baseball pitching velocity, the functional reach test (FR) and the simple reaction times (SRT) in young amateur baseball players after lumbar spine patterns of neuromuscular joint facilitation (NJF) treatment. [Subjects] The subjects were 11 young amateur baseball players. An NJF intervention and a proprioceptive neuromuscular facilitation (PNF) intervention were performed. The interventions were performed one after the other with one week between them. The order of the interventions was completely randomized. [Methods] The baseball pitching velocity, the FR and the SRT were evaluated before and after treatment. [Results] In the NJF group, there were significant differences in baseball pitching velocity, FR and SRT after treatment. In the PNF group, there was a significant difference in SRT after treatment. [Conclusion] NJF intervention shortens the SRT, increases the baseball pitching velocity and FR, and may be recommended to improve performance in baseball players.

Movement Patterns of a U-20 National Women's Soccer Team during Competitive Matches: Influence of Playing Position and Performance in the First Half.

PubMed

Ramos, Guilherme Passos; Nakamura, Fábio Yuzo; Pereira, Lucas Adriano; Junior, Wanderley Brilhante; Mahseredjian, Fábio; Wilke, Carolina Franco; Garcia, Emerson Silami; Coimbra, Cândido Celso

2017-09-01

The aim of this study was to determine the match locomotor characteristics of a sample of U-20 Brazilian female soccer players. Seven international matches were analyzed during the 2015 U-20 South American Championship, using global positioning technology. During a typical match, fullbacks and forwards covered greater distances in high-intensity running and sprinting than central defenders and midfielders (effect size [ES]=1.42-3.69). In the final 15 min of a game, total and high-intensity running distance and player load were ≈20 to 35% (ES=0.41-3.86) lower than in the first 15 min period for midfielders, fullbacks, forwards, and central defenders. Sprinting, and high-intensity running distances, and the frequency of accelerations >2 m . s -2 immediately after the most intense 5-min period declined in forwards (ES=1.78-2.67), fullbacks (ES=1.96-5.25), midfielders (ES=1.66-3.77), and central defenders (ES=1.50-4.22). Maintaining 'high' levels of activity in the first half resulted in ≈19% reductions in the second half for sprinting distance and frequency of accelerations >2 m . s -2 (ES=0.43 and 0.88), while increases in these locomotor activities were observed in situations with 'low' levels of activity (ES=0.64 and 1.12, for sprinting and accelerations >2 m . s -2 , respectively) (within-subject analysis). The data demonstrate that high-intensity efforts are reduced during various phases of international matches and overall activity patterns vary among playing positions. This information could be useful in the development and prescription of sex- and age-specific training regimes. © Georg Thieme Verlag KG Stuttgart · New York.

Effect of Leg Dominance on The Center-of-Mass Kinematics During an Inside-of-the-Foot Kick in Amateur Soccer Players.

PubMed

Zago, Matteo; Motta, Andrea Francesco; Mapelli, Andrea; Annoni, Isabella; Galvani, Christel; Sforza, Chiarella

2014-09-29

Soccer kicking kinematics has received wide interest in literature. However, while the instep-kick has been broadly studied, only few researchers investigated the inside-of-the-foot kick, which is one of the most frequently performed techniques during games. In particular, little knowledge is available about differences in kinematics when kicking with the preferred and non-preferred leg. A motion analysis system recorded the three-dimensional coordinates of reflective markers placed upon the body of nine amateur soccer players (23.0 ± 2.1 years, BMI 22.2 ± 2.6 kg/m2), who performed 30 pass-kicks each, 15 with the preferred and 15 with the non-preferred leg. We investigated skill kinematics while maintaining a perspective on the complete picture of movement, looking for laterality related differences. The main focus was laid on: anatomical angles, contribution of upper limbs in kick biomechanics, kinematics of the body Center of Mass (CoM), which describes the whole body movement and is related to balance and stability. When kicking with the preferred leg, CoM displacement during the ground-support phase was 13% higher (p<0.001), normalized CoM height was 1.3% lower (p<0.001) and CoM velocity 10% higher (p<0.01); foot and shank velocities were about 5% higher (p<0.01); arms were more abducted (p<0.01); shoulders were rotated more towards the target (p<0.01, 6° mean orientation difference). We concluded that differences in motor control between preferred and non-preferred leg kicks exist, particularly in the movement velocity and upper body kinematics. Coaches can use these results to provide effective instructions to players in the learning process, moving their focus on kicking speed and upper body behavior.

The efficacy of a movement control exercise programme to reduce injuries in youth rugby: a cluster randomised controlled trial

PubMed Central

Hislop, M D; Stokes, K A; Williams, S; McKay, C D; England, M; Kemp, S P T

2016-01-01

Background Injuries to youth rugby players have become an increasingly prominent health concern, highlighting the importance of developing and implementing appropriate preventive strategies. A growing body of evidence from other youth sports has demonstrated the efficacy of targeted exercise regimens to reduce injury risk. However, studies have yet to investigate the effect of such interventions in youth contact sport populations like rugby union. Objective To determine the efficacy of an evidence-based movement control exercise programme compared with a sham exercise programme to reduce injury risk in youth rugby players. Exercise programme compliance between trial arms and the effect of coach attitudes on compliance will also be evaluated. Setting School rugby coaches in England will be the target of the researcher intervention, with the effects of the injury prevention programmes being measured in male youth players aged 14–18 years in school rugby programmes over the 2015–2016 school winter term. Methods A cluster-randomised controlled trial with schools randomly allocated to either a movement control exercise programme or a sham exercise programme, both of which are coach-delivered. Injury measures will derive from field-based injury surveillance, with match and training exposure and compliance recorded. A questionnaire will be used to evaluate coach attitudes, knowledge, beliefs and behaviours both prior to and on the conclusion of the study period. Outcome measures Summary injury measures (incidence, severity and burden) will be compared between trial arms, as will the influence of coach attitudes on compliance and injury burden. Additionally, changes in these outcomes through using the exercise programmes will be evaluated. Trial registration number ISRTCNN13422001. PMID:27900148

Performance on the Functional Movement Screen Is Related to Hop Performance But Not to Hip and Knee Strength in Collegiate Football Players.

PubMed

Willigenburg, Nienke; Hewett, Timothy E

2017-03-01

To define the relationship between Functional Movement Screen (FMS) scores and hop performance, hip strength, and knee strength in collegiate football players. Cross-sectional cohort. Freshmen of a Division I collegiate American football team (n = 59). The athletes performed the FMS, and also a variety of hop tests, isokinetic knee strength, and isometric hip strength tasks. We recorded total FMS score, peak strength, and hop performance, and we calculated asymmetries between legs on the different tasks. Spearman correlation coefficients quantified the relationships between these measures, and χ analyses compared the number of athletes with asymmetries on the different tasks. We observed significant correlations (r = 0.38-0.56, P ≤ 0.02) between FMS scores and hop distance but not between FMS scores and hip or knee strength (all P ≥ 0.21). The amount of asymmetry on the FMS test was significantly correlated to the amount of asymmetry on the timed 6-m hop (r = 0.44, P < 0.01) but not to hip or knee strength asymmetries between limbs (all P ≥ 0.34). Functional Movement Screen score was positively correlated to hop distance, and limb asymmetry in FMS tasks was correlated to limb asymmetry in 6-m hop time in football players. No significant correlations were observed between FMS score and hip and knee strength or between FMS asymmetry and asymmetries in hip and knee strength between limbs. These results indicate that a simple hop for distance test may be a time-efficient and cost-efficient alternative to FMS testing in athletes and that functional asymmetries between limbs do not coincide with strength asymmetries.

Movement Demands and Running Intensities of Semi-Professional Rugby League Players during A 9’s Tournament: A Case Study

PubMed Central

Inglis, Paul; Bird, Stephen P.

2017-01-01

The objective of the study was to describe the movement demands and running intensities of semi-professional rugby league players during a rugby league 9’s (RL9’s) tournament. Six semi-professional rugby league players competed in a RL9’s tournament over a two-day period comprising of six games. Movement demands and running intensities were recorded using Global Positioning System (GPS) devices providing data on distance and speeds. Data is presented as mean (95% Confidence Intervals) with changes (≥ 75%) likely to exceed the smallest worthwhile change (0.2) considered practically important. Outside backs performed significantly (p < 0.05) more relative VHSR (3.9 m [3.5-4.3] vs 2.4 m [2.1-2.8]) absolute (97.7 m [81.3-114.1] vs 22.6m [15.8-29.3]) and relative (5.0 m·min-1 [4.2-5.9] vs 1.2 m·min-1 [0.8-1.6]) sprint distance than the forwards. Outside backs also performed significantly (p < 0.05) more absolute (97.7 m [81.3-114.1] vs 43.9 m [27.2-60.7]) and relative (5.0 m·min-1 [4.2-5.9] vs 2.3 m·min-1 [1.4-3.2]) sprint distance than the adjustables. Moderate (0.6 – 1.2) to very large (> 2.0) decreases in performance variables were observed over the two days. The biggest magnitude of change over the two days was seen with very large decreases in relative HSR (- 2.10) and sprint (- 2.14) distance. Between playing groups, the outside backs had the biggest decrease in running intensity with a very large (- 2.32) significant (p < 0.05) decrease in VHSR on day 2 (3.3 m·min-1 [2.5 – 4.1]) compared to day 1 (4.9 m·min-1 [4.4 – 5.4]). Running intensities are decreased during an intensified RL9’s tournament in semi-professional rugby league players. The observed decreases in running performances between playing groups are in agreement with previous research and may support the use of individualized player monitoring and recovery management during a RL9’s tournament-style competition. Key points Running intensities are decreased during an intensified rugby league 9’s tournament in semi-professional rugby league players. Forwards and backs performed significantly less high-intensity sprint efforts on day two than day one of the tournament. Appropriate planning and implementation of recovery strategies between games may reduce the potential effects of residual fatigue. PMID:28344447

The incidence and distribution of stress fractures in elite tennis players

PubMed Central

Maquirriain, J; Ghisi, J P

2006-01-01

Background Modern professional tennis involves powerful movements repeatedly subjecting the musculoskeletal system to heavy mechanical load. Thus tennis players are exposed to high risk of overuse injuries including stress fractures. Objective To determine the incidence and distribution of stress fractures in elite tennis players. Study design Retrospective cohort study. Methods The cohort study population consisted of 139 elite players (mean (SD) age, 20.0 (5.0) years; 48 female, 91 male). Stress fractures were identified and confirmed radiologically from medical records during a two year period. Injuries were analysed according to age, sex, site, severity, delay in diagnosis, and time needed to return to sports. Results 15 players sustained 18 stress fractures, corresponding to an overall case incidence of 12.9% (95% confidence interval (CI), 8.1 to 20.0). The tarsal navicular was most affected (n = 5; 27%), followed by the pars interarticularis (n = 3; 16%), the metatarsals (n = 3; 16%), the tibia (n = 2; 11%) and the lunate (n = 2; 11%). Magnetic resonance imaging showed a greater incidence of “high grade” lesions (94.4%). Stress fracture incidence was significantly higher in juniors (20.3% (95% CI, 11.4 to 33.2)) than in professional players (7.5% (2.8 to 15.6)) (p = 0.045). Conclusions There was a high absolute risk (12.9%) of stress fractures in elite tennis players over a two year period. Junior players were at highest risk. The lesions are a major cause of disruption both of training and of competition. Risk factors should therefore be identified and prevention emphasised. PMID:16632579

The effects of differential and variable training on the quality parameters of a handball throw.

PubMed

Wagner, Herbert; Müller, Erich

2008-01-01

The aim of this study was to undertake a comprehensive temporal, effective, and practical training study (variable and differential learning) that would offer athletes the opportunity to increase their performance, and to analyse the effects by measuring kinematics and quality parameters. Two participants of differing standards--a player of the first Austrian League and an Olympic and World Champion--but of similar anthropometric characteristics were recruited. One of the participants (Austrian League) was tested on five different occasions (pre-test and four retests) to measure the effects of four different training phases using kinematic analysis. The results of the study indicate an increase in ball velocity within the differential training phases (first, second, and fourth phases), different proximal-to-distal sequences of the participants, and a change of movement pattern during training measured by the segment velocities and the angle-time courses.

Physical Performance in Elite Male and Female Team Handball Players.

PubMed

Wagner, Herbert; Fuchs, Patrick; Fusco, Andrea; Fuchs, Philip; Bell, W Jeffrey; Duvillard, Serge P

2018-06-12

Biological differences between men and women are well known; however, literature-addressing knowledge about the influence of sex to specific and general performance in team handball is almost nonexistent. Consequently, the aim of the study was to assess and compare specific and general physical performance in male and female elite team handball players, to determine if the differences are consequential for general compared to specific physical performance characteristics and the relationship between general and specific physical performance. Twelve male and ten female elite team handball players performed a game based performance test, upper- und lower-body strength and power tests, a sprinting test, and an incremental treadmill-running test. Significant differences (P<.05) between male and female players were found for peak oxygen uptake and total running time during the treadmill test, 30m sprinting time, leg extension strength, trunk and shoulder rotation torque, counter movement jump height as well as offense and defense time, ball velocity and jump height in the game based performance test. An interaction (sex × test) was found for time and oxygen uptake and except shoulder rotation torque and ball velocity in females, we found only a low relationship between specific and general physical performance. The results of the study revealed that male players are heavier, taller, faster, stronger, jump higher and have a better aerobic performance. However, female players performed relatively better in the team handball specific tests compared to the general tests. Our findings also suggest that female players should focus more on strength training.

Parasocial interaction with my avatar: effects of interdependent self-construal and the mediating role of self-presence in an avatar-based console game, Wii.

PubMed

Jin, Seung-A Annie; Park, Namkee

2009-12-01

The "self" concept has grown increasingly important in interactive media environments. This study investigated self-related processes in an avatar-based game console, Wii. A key feature of the Wii is its motion-sensing capability that empowers players to manipulate and interact with items on-screen via movement. The present study examined the effects of video game players' self-construal on parasocial interaction with their avatars and feelings of self-presence. In this study, parasocial interaction was operationally defined as the extent of game players' interpersonal involvement with their avatar and the extent to which game players perceive themselves as interacting with the avatar. Self-presence was defined as the degree to which video game players feel as if their avatar on the screen were their real self. Based on an experiment, the study discovered that game players with high interdependent self-construal showed closer parasocial interaction and higher level of self-presence than those with low interdependent self-construal. Results also showed that self-presence mediated the effects of interdependent self-construal on the parasocial relationship with game players' avatars. Thus, the study discovered an important individual difference factor, interdependent self-construal, affecting the degree to which people form a parasocial relationship with their virtual self that is visually manifested in the form of an avatar. In addition, the present study added empirical evidence about the mediating role played by self-presence in avatar-based video games.

Effects of Small-Sided Games vs. Interval Training in Aerobic Fitness and Physical Enjoyment in Young Elite Soccer Players

PubMed Central

Martín, Juan; Lerga, Javier; Sánchez, Felipe; Villagra, Federico; Zulueta, Javier J.

2015-01-01

The purpose of this study was to compare the effects of Small-Sided Games (SSG) vs. Interval Training (IT) in soccer training on aerobic fitness and physical enjoyment in youth elite soccer players during the last 8 weeks of the season. Seventeen U-16 male soccer players (age = 15.5 ± 0.6 years, and 8.5 years of experience) of a Spanish First Division club academy were randomized to 2 different groups for 6 weeks: SSG group (n = 9) and IT group (n = 8). In addition to the usual technical and tactical sessions and competitive games, the SSG group performed 11 sessions with different SSGs, whereas the IT group performed the same number of sessions of IT. Players were tested before and after the 6-week training intervention with a continuous maximal multistage running field test and the counter movement jump test (CMJ). At the end of the study, players answered the physical activity enjoyment scale (PACES). During the study, heart rate (HR) and session perceived effort (sRPE) were assessed. SSGs were as effective as IT in maintaining the aerobic fitness in elite young soccer players during the last weeks of the season. Players in the SSG group declared a greater physical enjoyment than IT (P = 0.006; ES = 1.86 ± 1.07). Coaches could use SSG training during the last weeks of the season as an option without fear of losing aerobic fitness while promoting high physical enjoyment. PMID:26331623

Using budget-friendly methods to analyze sport specific movements

NASA Astrophysics Data System (ADS)

Jackson, Lindsay; Williams, Sarah; Ferrara, Davon

2015-03-01

When breaking down the physics behind sport specific movements, athletes, usually professional, are often assessed in multimillion-dollar laboratories and facilities. Budget-friendly methods, such as video analysis using low-cost cameras, iPhone sensors, or inexpensive force sensors can make this process more accessible to amateur athletes, which in-turn can give insight into injury mechanisms. Here we present a comparison of two methods of determining the forces experienced by a cheerleader during co-education stunting and soccer goalies while side-diving. For the cheerleader, accelerometer measurements were taken by an iPhone 5 and compared to video analysis. The measurements done on the soccer players were taken using FlexiForce force sensors and again compared to video analysis. While these budget-friendly methods could use some refining, they show promise for producing usable measurements for possibly increasing our understanding of injury in amateur players. Furthermore, low-cost physics experiments with sports can foster an active learning environment for students with minimum physics and mathematical background.

Injuries to the Collateral Ligaments of the Metacarpophalangeal Joint of the Thumb, Including Simultaneous Combined Thumb Ulnar and Radial Collateral Ligament Injuries, in National Football League Athletes.

PubMed

Werner, Brian C; Belkin, Nicole S; Kennelly, Steve; Weiss, Leigh; Barnes, Ronnie P; Rodeo, Scott A; Warren, Russell F; Hotchkiss, Robert N

2017-01-01

Thumb collateral ligament injuries occur frequently in the National Football League (NFL). In the general population or in recreational athletes, pure metacarpophalangeal (MCP) abduction or adduction mechanisms yield isolated ulnar collateral ligament (UCL) and radial collateral ligament (RCL) tears, respectively, while NFL athletes may sustain combined mechanism injury patterns. To evaluate the incidence of simultaneous combined thumb UCL and RCL tears among all thumb MCP collateral ligament injuries in NFL athletes on a single team. Case series; Level of evidence, 4. A retrospective review of all thumb injuries on a single NFL team from 1991 to 2014 was performed. All players with a thumb MCP collateral ligament injury were included. Collateral ligament injuries were confirmed by review of both physical examination findings and magnetic resonance imaging. Player demographics, surgical details, and return-to-play data were obtained from the team electronic medical record and surgeons' records. A total of 36 thumbs in 32 NFL players were included in the study, yielding an incidence of 1.6 thumb MCP collateral ligament injuries per year on a single NFL team. Of these, 9 thumbs (25%) had a simultaneous combined UCL and RCL tear injury pattern confirmed on both physical examination and MRI. The remaining 27 thumbs (75%) were isolated UCL injuries. All combined UCL/RCL injuries required surgery due to dysfunction from instability; 63.0% of isolated UCL injuries required surgical repair ( P = .032) due to continued pain and dysfunction from instability. Repair, when required, was delayed until the end of the season. All players with combined UCL/RCL injuries and isolated UCL injuries returned to play professional football the following season. Simultaneous combined thumb UCL and RCL tear is a previously undescribed injury pattern that occurred in 25% of thumb MCP collateral ligament injuries on a single NFL team over a 23-year period. All players with combined thumb UCL/RCL injuries required surgical repair, which was significantly higher compared with players with isolated UCL injuries. Team physicians and hand surgeons treating elite football players with suspected thumb collateral ligament injuries should examine for RCL and UCL instability and consider MRI if any concern exists for a combined ligament injury pattern, as this injury is likely frequently missed.

Prone Hip Extension Muscle Recruitment is Associated with Hamstring Injury Risk in Amateur Soccer.

PubMed

Schuermans, Joke; Van Tiggelen, Damien; Witvrouw, Erik

2017-09-01

'Core stability' is considered essential in rehabilitation and prevention. Particularly with respect to hamstring injury prevention, assessment and training of lumbo-pelvic control is thought to be key. However, supporting scientific evidence is lacking. To explore the importance of proximal neuromuscular function with regard to hamstring injury susceptibility, this study investigated the association between the Prone Hip Extension (PHE) muscle activation pattern and hamstring injury incidence in amateur soccer players. 60 healthy male soccer players underwent a comprehensive clinical examination, comprising a range of motion assessments and the investigation of the posterior chain muscle activation pattern during PHE. Subsequently, hamstring injury incidence was recorded prospectively throughout a 1.5-season monitoring period. Players who were injured presented a PHE activation pattern that differed significantly from those who did not. Contrary to the controls, hamstring activity onset was significantly delayed (p=0.018), resulting in a shifted activation sequence. Players were 8 times more likely to get injured if the hamstring muscles were activated after the lumbar erector spinae instead of vice versa (p=0.009). Assessment of muscle recruitment during PHE demonstrated to be useful in injury prediction, suggesting that neuromuscular coordination in the posterior chain influences hamstring injury vulnerability. © Georg Thieme Verlag KG Stuttgart · New York.

The Linear Quadratic Gaussian Multistage Game with Nonclassical Information Pattern Using a Direct Solution Method

NASA Astrophysics Data System (ADS)

Clemens, Joshua William

Game theory has application across multiple fields, spanning from economic strategy to optimal control of an aircraft and missile on an intercept trajectory. The idea of game theory is fascinating in that we can actually mathematically model real-world scenarios and determine optimal decision making. It may not always be easy to mathematically model certain real-world scenarios, nonetheless, game theory gives us an appreciation for the complexity involved in decision making. This complexity is especially apparent when the players involved have access to different information upon which to base their decision making (a nonclassical information pattern). Here we will focus on the class of adversarial two-player games (sometimes referred to as pursuit-evasion games) with nonclassical information pattern. We present a two-sided (simultaneous) optimization solution method for the two-player linear quadratic Gaussian (LQG) multistage game. This direct solution method allows for further interpretation of each player's decision making (strategy) as compared to previously used formal solution methods. In addition to the optimal control strategies, we present a saddle point proof and we derive an expression for the optimal performance index value. We provide some numerical results in order to further interpret the optimal control strategies and to highlight real-world application of this game-theoretic optimal solution.

The Spawns of Creative Behavior in Team Sports: A Creativity Developmental Framework.

PubMed

Santos, Sara D L; Memmert, Daniel; Sampaio, Jaime; Leite, Nuno

2016-01-01

Developing creativity in team sports players is becoming an increasing focus in sports sciences. The Creativity Developmental Framework is presented to provide an updated science based background. This Framework describes five incremental creative stages (beginner, explorer, illuminati, creator, and rise) and combines them into multidisciplinary approaches embodied in creative assumptions. In the first training stages, the emphasis is placed on the enrollment in diversification, deliberate play and physical literacy approaches grounded in nonlinear pedagogies. These approaches allow more freedom to discover different movement patterns increasing the likelihood of emerging novel, adaptive and functional solutions. In the later stages, the progressive specialization in sports and the differential learning commitment are extremely important to push the limits of the creative progress at higher levels of performance by increasing the range of skills configurations. Notwithstanding, during all developmental stages the teaching games for understanding, a game-centered approach, linked with the constraints-led approach play an important role to boost the tactical creative behavior. Both perspectives might encourage players to explore all actions possibilities (improving divergent thinking) and prevents the standardization in their actions. Overall, considering the aforementioned practice conditions the Creativity Developmental Framework scrutinizes the main directions that lead to a long-term improvement of the creative behavior in team sports. Nevertheless, this framework should be seen as a work in progress to be later used as the paramount reference in creativity training.

The Spawns of Creative Behavior in Team Sports: A Creativity Developmental Framework

PubMed Central

Santos, Sara D. L.; Memmert, Daniel; Sampaio, Jaime; Leite, Nuno

2016-01-01

Developing creativity in team sports players is becoming an increasing focus in sports sciences. The Creativity Developmental Framework is presented to provide an updated science based background. This Framework describes five incremental creative stages (beginner, explorer, illuminati, creator, and rise) and combines them into multidisciplinary approaches embodied in creative assumptions. In the first training stages, the emphasis is placed on the enrollment in diversification, deliberate play and physical literacy approaches grounded in nonlinear pedagogies. These approaches allow more freedom to discover different movement patterns increasing the likelihood of emerging novel, adaptive and functional solutions. In the later stages, the progressive specialization in sports and the differential learning commitment are extremely important to push the limits of the creative progress at higher levels of performance by increasing the range of skills configurations. Notwithstanding, during all developmental stages the teaching games for understanding, a game-centered approach, linked with the constraints-led approach play an important role to boost the tactical creative behavior. Both perspectives might encourage players to explore all actions possibilities (improving divergent thinking) and prevents the standardization in their actions. Overall, considering the aforementioned practice conditions the Creativity Developmental Framework scrutinizes the main directions that lead to a long-term improvement of the creative behavior in team sports. Nevertheless, this framework should be seen as a work in progress to be later used as the paramount reference in creativity training. PMID:27617000

Development of an Agility Test for Badminton Players and Assessment of Its Validity and Test-Retest Reliability.

PubMed

Loureiro, Luiz de França Bahia; de Freitas, Paulo Barbosa

2016-04-01

Badminton requires open and fast actions toward the shuttlecock, but there is no specific agility test for badminton players with specific movements. To develop an agility test that simultaneously assesses perception and motor capacity and examine the test's concurrent and construct validity and its test-retest reliability. The Badcamp agility test consists of running as fast as possible to 6 targets placed on the corners and middle points of a rectangular area (5.6 × 4.2 m) from the start position located in the center of it, following visual stimuli presented in a luminous panel. The authors recruited 43 badminton players (17-32 y old) to evaluate concurrent (with shuttle-run agility test--SRAT) and construct validity and test-retest reliability. Results revealed that Badcamp presents concurrent and construct validity, as its performance is strongly related to SRAT (ρ = 0.83, P < .001), with performance of experts being better than nonexpert players (P < .01). In addition, Badcamp is reliable, as no difference (P = .07) and a high intraclass correlation (ICC = .93) were found in the performance of the players on 2 different occasions. The findings indicate that Badcamp is an effective, valid, and reliable tool to measure agility, allowing coaches and athletic trainers to evaluate players' athletic condition and training effectiveness and possibly detect talented individuals in this sport.

Making neurorehabilitation fun: Multiplayer training via damping forces balancing differences in skill levels.

PubMed

Baur, Kilian; Wolf, Peter; Riener, Robert; Duarte, Jaime E

2017-07-01

Multiplayer environments are thought to increase the training intensity in robot-aided rehabilitation therapy after stroke. We developed a haptic-based environment to investigate the dynamics of two-player training performing time-constrained reaching movements using the ARMin rehabilitation robot. We implemented a challenge level adaptation algorithm that controlled a virtual damping coefficient to reach a desired success rate. We tested the algorithm's effectiveness in regulating the success rate during game play in a simulation with computer-controlled players, in a feasibility study with six unimpaired players, and in a single session with one stroke patient. The algorithm demonstrated its capacity to adjust the damping coefficient to reach three levels of success rate (low [50%], moderate [70%], and high [90%]) during singleplayer and multiplayer training. For the patient - tested in single-player mode at the moderate success rate only - the algorithm showed also promising behavior. Results of the feasibility study showed that to increase the player's willingness to play at a more challenging task condition, the effect of the challenge level adaptation - regardless of being played in single player or multiplayer mode - might be more important than the provision of multiplayer setting alone. Furthermore, the multiplayer setting tends to be a motivating and encouraging therapy component. Based on these results we will optimize and expand the multiplayer training platform and further investigate multiplayer settings in stroke therapy.

Causes of anterior cruciate ligament injuries.

PubMed

Ristić, Vladimir; Ninković, Srdan; Harhaji, Vladimir; Milankov, Miroslav

2010-01-01

In order to prevent anterior cruciate ligament injuries it is necessary to define risk factors and to analyze the most frequent causes of injuries--that being the aim of this study. The study sample consisted of 451 surgically treated patients, including 400 sportsmen (65% of them being active and 35% recreational sportsmen), 29% female and 71% male; of whom 90% were younger than 35. Sports injuries, as the most frequent cause of anterior cruciate ligament injuries, were recorded in 88% of patients (non-contact ones in 78% and contact ones in 22%), injuries occurring in everyday activities in 11% and in traffic in 1%. Among sportsmen, reconstruction of the anterior cruciate ligament was most frequently performed in football players (48%), then in handball players (22%), basketball players (13%), volleyball players (8%), martial arts fighters (4%). However, the injury incidence was the highest among the active basketball players (1 injured among 91 active players). Type of footwear, warming up before the activity, genetic predisposition and everyday therapy did not have a significant influence on getting injured. Anterior cruciate ligament injuries happened three times more often during matches, in the middle and at the end of a match and training session (79%), at landing after the jump or when changing direction of movement (75%) without a contact with other competitors, on dry surfaces (79%), among not so well prepared sportsmen.

Impact of playing American professional football on long-term brain function.

PubMed

Amen, Daniel G; Newberg, Andrew; Thatcher, Robert; Jin, Yi; Wu, Joseph; Keator, David; Willeumier, Kristen

2011-01-01

The authors recruited 100 active and former National Football League players, representing 27 teams and all positions. Players underwent a clinical history, brain SPECT imaging, qEEG, and multiple neuropsychological measures, including MicroCog. Relative to a healthy-comparison group, players showed global decreased perfusion, especially in the prefrontal, temporal, parietal, and occipital lobes, and cerebellar regions. Quantitative EEG findings were consistent, showing elevated slow waves in the frontal and temporal regions. Significant decreases from normal values were found in most neuropsychological tests. This is the first large-scale brain-imaging study to demonstrate significant differences consistent with a chronic brain trauma pattern in professional football players.

Computer games and fine motor skills.

PubMed

Borecki, Lukasz; Tolstych, Katarzyna; Pokorski, Mieczyslaw

2013-01-01

The study seeks to determine the influence of computer games on fine motor skills in young adults, an area of incomplete understanding and verification. We hypothesized that computer gaming could have a positive influence on basic motor skills, such as precision, aiming, speed, dexterity, or tremor. We examined 30 habitual game users (F/M - 3/27; age range 20-25 years) of the highly interactive game Counter Strike, in which players impersonate soldiers on a battlefield, and 30 age- and gender-matched subjects who declared never to play games. Selected tests from the Vienna Test System were used to assess fine motor skills and tremor. The results demonstrate that the game users scored appreciably better than the control subjects in all tests employed. In particular, the players did significantly better in the precision of arm-hand movements, as expressed by a lower time of errors, 1.6 ± 0.6 vs. 2.8 ± 0.6 s, a lower error rate, 13.6 ± 0.3 vs. 20.4 ± 2.2, and a shorter total time of performing a task, 14.6 ± 2.9 vs. 32.1 ± 4.5 s in non-players, respectively; p < 0.001 all. The findings demonstrate a positive influence of computer games on psychomotor functioning. We submit that playing computer games may be a useful training tool to increase fine motor skills and movement coordination.

Event-Related Beta EEG Changes During Active, Passive Movement and Functional Electrical Stimulation of the Lower Limb.

PubMed

Qiu, Shuang; Yi, Weibo; Xu, Jiapeng; Qi, Hongzhi; Du, Jingang; Wang, Chunfang; He, Feng; Ming, Dong

2016-02-01

A number of electroencephalographic (EEG) studies have reported on event-related desynchronization/synchronization (ERD/ERS) during active movements, passive movements, and the movements induced by functional electrical stimulation (FES). However, the quantitative differences in ERD values and affected frequency bands associated with the lower limb have not been discussed. The goal of this paper was to quantitatively compare the ERD patterns during active movement, passive movement and FES-induced movement of the lower limb. 64-channel EEG signals were recorded to investigate the brain oscillatory patterns during active movement, passive movement and FES-induced movement of the lower limb in twelve healthy subjects. And passive movement and FES-induced movement were also performed in a hemiplegic stroke patient. For healthy subjects, FES-induced movement presented significantly higher characteristic frequency of central beta ERD while there was no significant difference in ERD values compared with active or passive movement. Meanwhile, beta ERD values of FES-induced movement were significantly correlated with those of active movement, and spatial distribution of beta ERD pattern for FES-induced movement was more correlated with that for active movement. In addition, the stroke patient presented central ERD patterns during FES-induced movement, while no ERD with similar frequencies could be found during passive movement. This work implies that the EEG oscillatory pattern under FES-induced movement tends more towards active movement instead of passive movement. The quantification of ERD patterns could be expected as a potential technique to evaluate the brain response during FES-induced movement.

Do force-time and power-time measures in a loaded jump squat differentiate between speed performance and playing level in elite and elite junior rugby union players?

PubMed

Hansen, Keir T; Cronin, John B; Pickering, Stuart L; Douglas, Lee

2011-09-01

The purpose of this study was to investigate the discriminative ability of rebound jump squat force-time and power-time measures in differentiating speed performance and competition level in elite and elite junior rugby union players. Forty professional rugby union players performed 3 rebound jump squats with an external load of 40 kg from which a number of force-time and power-time variables were acquired and analyzed. Additionally, players performed 3 sprints over 30 m with timing gates at 5, 10, and 30 m. Significant differences (p < 0.05) between the fastest 20 and slowest 20 athletes, and elite (n = 25) and elite junior (n = 15) players in speed and force-time and power-time variables were determined using independent sample t-tests. The fastest and slowest sprinters over 10 m differed in peak power (PP) expressed relative to body weight. Over 30 m, there were significant differences in peak velocity and relative PP and rate of power development. There was no significant difference in speed over any distance between elite and elite junior rugby union players; however, a number of force and power variables including peak force, PP, force at 100 milliseconds from minimum force, and force and impulse 200 milliseconds from minimum force were significantly (p < 0.05) different between playing levels. Although only power values expressed relative to body weight were able to differentiate speed performance, both absolute and relative force and power values differentiated playing levels in professional rugby union players. For speed development in rugby union players, training strategies should aim to optimize the athlete's power to weight ratio, and lower body resistance training should focus on movement velocity. For player development to transition elite junior players to elite status, adding lean mass is likely to be most beneficial.

Are poker players all the same? Latent class analysis.

PubMed

Dufour, Magali; Brunelle, Natacha; Roy, Élise

2015-06-01

Poker is the gambling game that is currently gaining the most in popularity. However, there is little information on poker players' characteristics and risk factors. Furthermore, the first studies described poker players, often recruited in universities, as an homogeneous group who played in only one of the modes (land based or on the Internet). This study aims to identify, through latent class analyses, poker player subgroups. A convenience sample of 258 adult poker players was recruited across Quebec during special events or through advertising in various media. Participants filled out a series of questionnaires (Canadian Problem Gambling Index, Beck Depression, Beck Anxiety, erroneous belief and alcohol/drug consumption). The latent class analysis suggests that there are three classes of poker players. Class I (recreational poker players) includes those who have the lowest probability of engaging intensively in different game modes. Participants in class II (Internet poker players) all play poker on the Internet. This class includes the highest proportion of players who consider themselves experts or professionals. They make a living in part or in whole from poker. Class III (multiform players) includes participants with the broadest variety of poker patterns. This group is complex: these players are positioned halfway between professional and recreational players. Results indicate that poker players are not an homogeneous group identified simply on the basis of the form of poker played. The specific characteristics associated with each subgroup points to vulnerabilities that could potentially be targeted for preventive interventions.

Modifying patterns of movement in people with low back pain -does it help? A systematic review.

PubMed

Laird, Robert A; Kent, Peter; Keating, Jennifer L

2012-09-07

Physiotherapy for people with low back pain frequently includes assessment and modification of lumbo-pelvic movement. Interventions commonly aim to restore normal movement and thereby reduce pain and improve activity limitation. The objective of this systematic review was to investigate: (i) the effect of movement-based interventions on movement patterns (muscle activation, lumbo-pelvic kinematics or postural patterns) of people with low back pain (LBP), and (ii) the relationship between changes in movement patterns and subsequent changes in pain and activity limitation. MEDLINE, Cochrane Central, EMBASE, AMI, CINAHL, Scopus, AMED, ISI Web of Science were searched from inception until January 2012. Randomised controlled trials or controlled clinical trials of people with LBP were eligible for inclusion. The intervention must have been designed to influence (i) muscle activity patterns, (ii) lumbo-pelvic kinematic patterns or (iii) postural patterns, and included measurement of such deficits before and after treatment, to allow determination of the success of the intervention on the lumbo-pelvic movement. Twelve trials (25% of retrieved studies) met the inclusion criteria. Two reviewers independently identified, assessed and extracted data. The PEDro scale was used to assess method quality. Intervention effects were described using standardised differences between group means and 95% confidence intervals. The included trials showed inconsistent, mostly small to moderate intervention effects on targeted movement patterns. There was considerable heterogeneity in trial design, intervention type and outcome measures. A relationship between changes to movement patterns and improvements in pain or activity limitation was observed in one of six studies on muscle activation patterns, one of four studies that examined the flexion relaxation response pattern and in two of three studies that assessed lumbo-pelvic kinematics or postural characteristics. Movement-based interventions were infrequently effective for changing observable movement patterns. A relationship between changes in movement patterns and improvement in pain or activity limitation was also infrequently observed. No independent studies confirm any observed relationships. Challenges for future research include defining best methods for measuring (i) movement aberrations, (ii) improvements in movements, and (iii) the relationship between changes in how people move and associated changes in other health indicators such as activity limitation.

Neuromechanical evidence of improved neuromuscular control around knee joint in volleyball players.

PubMed

Masci, Ilaria; Vannozzi, Giuseppe; Gizzi, Leonardo; Bellotti, Pasquale; Felici, Francesco

2010-02-01

The aim of the present work was to verify that skilled volleyball players present specific adaptations in both neuromuscular control and movement biomechanics, showing an improved neuromuscular control around the knee joint than in non-jumper athletes. Seven male volleyball players and seven male non-jumper athletes were recruited for this study. The following tests were performed in a random order: single countermovement jump (CMJ), single squat jump. At the end of the series, subjects performed a repetitive CMJ test. Electromyographic signals were recorded from vastus lateralis and biceps femoris muscles on both sides. Ground reaction forces and moments were measured with a force plate. Volleyball athletes performed better in all tests and were more resistant to fatigue than non-jumper athletes. Furthermore, volleyball athletes showed a reduced co-activation of knee flexor/extensor muscles. The present results seem to stand for a neural adaptation of the motor control scheme to training.

Speech recovery and language plasticity can be facilitated by Sensori-Motor Fusion training in chronic non-fluent aphasia. A case report study.

PubMed

Haldin, Célise; Acher, Audrey; Kauffmann, Louise; Hueber, Thomas; Cousin, Emilie; Badin, Pierre; Perrier, Pascal; Fabre, Diandra; Perennou, Dominic; Detante, Olivier; Jaillard, Assia; Lœvenbruck, Hélène; Baciu, Monica

2017-11-17

The rehabilitation of speech disorders benefits from providing visual information which may improve speech motor plans in patients. We tested the proof of concept of a rehabilitation method (Sensori-Motor Fusion, SMF; Ultraspeech player) in one post-stroke patient presenting chronic non-fluent aphasia. SMF allows visualisation by the patient of target tongue and lips movements using high-speed ultrasound and video imaging. This can improve the patient's awareness of his/her own lingual and labial movements, which can, in turn, improve the representation of articulatory movements and increase the ability to coordinate and combine articulatory gestures. The auditory and oro-sensory feedback received by the patient as a result of his/her own pronunciation can be integrated with the target articulatory movements they watch. Thus, this method is founded on sensorimotor integration during speech. The SMF effect on this patient was assessed through qualitative comparison of language scores and quantitative analysis of acoustic parameters measured in a speech production task, before and after rehabilitation. We also investigated cerebral patterns of language reorganisation for rhyme detection and syllable repetition, to evaluate the influence of SMF on phonological-phonetic processes. Our results showed that SMF had a beneficial effect on this patient who qualitatively improved in naming, reading, word repetition and rhyme judgment tasks. Quantitative measurements of acoustic parameters indicate that the patient's production of vowels and syllables also improved. Compared with pre-SMF, the fMRI data in the post-SMF session revealed the activation of cerebral regions related to articulatory, auditory and somatosensory processes, which were expected to be recruited by SMF. We discuss neurocognitive and linguistic mechanisms which may explain speech improvement after SMF, as well as the advantages of using this speech rehabilitation method.

Kinematic Analysis of Line-Out Throwing in Elite International Rugby Union

PubMed Central

Sayers, Mark G.L.

2011-01-01

The rugby union line-out is a key aspect of game play and involves players from both teams contesting for the ball after it has been thrown in from the side line. Successful lines-out throws require the ball to be delivered accurately to the hands of a jumping and/or lifted team mate (approximately 3-3.5 m off the ground) over distances of between 5- 18 m. Previous research has suggested considerable inter and intra-individual differences in the throwing techniques of international level players. Accordingly, this project investigated the interrelationships between accuracy and the line-out throwing characteristics of three elite international rugby players, and then analyzed whether these changed for throws over increasing length. Three-dimensional (3D) data were developed from video footage (50 Hz) of three elite international subjects for 30 throws over three distances (6 m, 10 m, and 15 m). Results showed notable differences between subjects in many variables at each of the key throw phases. However, several variables such as the degree of trunk flexion at the end of the backswing and at ball release, coupled with elbow flexion angle at ball release remained constant as throw length increased. All subjects exhibited high levels of consistency in movement patterns across all throw lengths. Findings indicated that these high performance line-out throwers shared several common characteristics that will provide useful guides in the development of training programs. Key points A key aspect of this research was the assessment of throwing accuracy using a functional throwing task that mimicked normal performance. Although individual differences in throwing technique occurred, several technical aspects of the throw were common to each of these elite international players. Subjects tended to be extremely consistent in the way they positioned the ball at the end of the backswing, and had very consistent elbow (flexion) and shoulder (flexion and abduction) angles at both the end of the backswing and at ball release. In addition, throwers kept the trunk close to upright during the throw with minimal trunk flexion or extension regardless of throw distance. To throw for longer distances participants tended to increase the involvement of the legs. PMID:24150632

Match-play demands of elite youth Gaelic football using global positioning system tracking.

PubMed

Reilly, Brian; Akubat, Ibrahim; Lyons, Mark; Collins, D Kieran

2015-04-01

Global positioning systems (GPS) technology has made athlete-tracking a convenient and accepted technique to specify movement patterns and physical demands in sport. The purpose of this study was to examine positional demands of elite youth Gaelic football match-play using portable GPS technology to examine movement patterns and heart rates across match periods. Fifty-six elite youth male Gaelic footballers (age, 15 ± 0.66 years) fitted with portable 4-Hz GPS units were observed during 6 competitive matches (60 minutes). Data provided from the GPS unit included total distance, high-intensity (≥17·km·h(-1)) distance, sprint (≥22 km·h(-1)) distance, and total number of sprints. Heart rate was monitored continuously throughout the games. Players covered a mean distance of 5732 ± 1047 m, and the mean intensity of match-play was 85% of the peak heart rate. There was a significant (p = 0.028) drop in the total distance covered in the second half (2783 ± 599 m) compared with the first half (2948 ± 580 m). In particular, there is a noticeable drop in the distance covered in the third quarter of the game (after half-time), which has implications for re-warming up at the end of the half-time interval. There was a highly significant (p < .001) difference in the distance traveled across the 5 positional groups with midfielders covering the greatest total distance (6740 ± 384 m). The significant differences found with respect to positional groups support the implementation of individual, position-specific strength and conditioning programs.

Korean American males' interracial contact experiences during serious leisure activity

Treesearch

KangJae Jerry Lee; David Scott

2012-01-01

This study investigated serious leisure among Korean Americans and examined the ways in which Koreans' marginalized status impact their pursuit of serious leisure and participation patterns in the context of recreational sports. Face-to-face, in-depth, and semi-structured interviews were conducted with 11 Korean basketball players and 4 soccer players.

Jump Landing Characteristics Predict Lower Extremity Injuries in Indoor Team Sports.

PubMed

van der Does, H T D; Brink, M S; Benjaminse, A; Visscher, C; Lemmink, K A P M

2016-03-01

The aim of this study is to investigate the predictive value of landing stability and technique to gain insight into risk factors for ankle and knee injuries in indoor team sport players. Seventy-five male and female basketball, volleyball or korfball players were screened by measuring landing stability after a single-leg jump landing and landing technique during a repeated counter movement jump by detailed 3-dimensional kinematics and kinetics. During the season 11 acute ankle injuries were reported along with 6 acute and 7 overuse knee injuries by the teams' physical therapist. Logistic regression analysis showed less landing stability in the forward and diagonal jump direction (OR 1.01-1.10, p≤0.05) in players who sustained an acute ankle injury. Furthermore landing technique with a greater ankle dorsiflexion moment increased the risk for acute ankle injury (OR 2.16, p≤0.05). A smaller knee flexion moment and greater vertical ground reaction force increased the risk of an overuse knee injury (OR 0.29 and 1.13 respectively, p≤0.05). Less one-legged landing stability and suboptimal landing technique were shown in players sustaining an acute ankle and overuse knee injury compared to healthy players. Determining both landing stability and technique may further guide injury prevention programs. © Georg Thieme Verlag KG Stuttgart · New York.

Exploring Team Passing Networks and Player Movement Dynamics in Youth Association Football

PubMed Central

Coutinho, Diogo; Santos, Sara; Lago-Penas, Carlos; Jiménez, Sergio; Sampaio, Jaime

2017-01-01

Understanding how youth football players base their game interactions may constitute a solid criterion for fine-tuning the training process and, ultimately, to achieve better individual and team performances during competition. The present study aims to explore how passing networks and positioning variables can be linked to the match outcome in youth elite association football. The participants included 44 male elite players from under-15 and under-17 age groups. A passing network approach within positioning-derived variables was computed to identify the contributions of individual players for the overall team behaviour outcome during a simulated match. Results suggested that lower team passing dependency for a given player (expressed by lower betweenness network centrality scores) and high intra-team well-connected passing relations (expressed by higher closeness network centrality scores) were related to better outcomes. The correlation between the dyads’ positioning regularity and the passing density showed a most likely higher correlation in under-15 (moderate effect), indicating a possible more dependence of the ball position rather than in the under-17 teams (small/unclear effects). Overall, this study emphasizes the potential of coupling notational analyses with spatial-temporal relations to produce a more functional and holistic understanding of teams’ sports performance. Also, the social network analysis allowed to reveal novel key determinants of collective performance. PMID:28141823

Specific physiological and biomechanical performance in elite, sub-elite and in non-elite male team handball players.

PubMed

Wagner, Herbert; Fuchs, Philip X; von Duvillard, Serge P

2018-01-01

Team handball is a dynamic sport game that is played professionally in numerous countries. However, knowledge about training and competition is based mostly on practical experience due to limited scientific studies. Consequently, the aims of our study were to compare specific physiological and biomechanical performance in elite, sub-elite and in non-elite male team handball players. Thirty-six elite, sub-elite and non-elite male team handball players performed a game based performance test, upper-body and lower-body strength tests, 30-m sprint test, counter movement jump test and an incremental treadmill running test. Significant differences (P<0.05) were found for the peak oxygen uptake, heart rate, offense and defense time, jump height and ball velocity during the jump throw in the game based performance test, maximal oxygen uptake in the incremental treadmill running test as well as in maximal leg strength and leg explosive strength in the isometric strength test. Elite male players have an enhanced specific agility, a better throwing performance, a higher team handball specific oxygen uptake and higher leg strength compared to sub-elite and non-elite players. Based on these results we recommend that training in team handball should focus on game based training methods to improve performance in specific agility, endurance and technique.

Coordination and variability in the elite female tennis serve.

PubMed

Whiteside, David; Elliott, Bruce Clifford; Lay, Brendan; Reid, Machar

2015-01-01

Enhancing the understanding of coordination and variability in the tennis serve may be of interest to coaches as they work with players to improve performance. The current study examined coordinated joint rotations and variability in the lower limbs, trunk, serving arm and ball location in the elite female tennis serve. Pre-pubescent, pubescent and adult players performed maximal effort flat serves while a 22-camera 500 Hz motion analysis system captured three-dimensional body kinematics. Coordinated joint rotations in the lower limbs and trunk appeared most consistent at the time players left the ground, suggesting that they coordinate the proximal elements of the kinematic chain to ensure that they leave the ground at a consistent time, in a consistent posture. Variability in the two degrees of freedom at the elbow became significantly greater closer to impact in adults, possibly illustrating the mechanical adjustments (compensation) these players employed to manage the changing impact location from serve to serve. Despite the variable ball toss, the temporal composition of the serve was highly consistent and supports previous assertions that players use the location of the ball to regulate their movement. Future work should consider these associations in other populations, while coaches may use the current findings to improve female serve performance.

An equilibrium-point model of electromyographic patterns during single-joint movements based on experimentally reconstructed control signals.

PubMed

Latash, M L; Goodman, S R

1994-01-01

The purpose of this work has been to develop a model of electromyographic (EMG) patterns during single-joint movements based on a version of the equilibrium-point hypothesis, a method for experimental reconstruction of the joint compliant characteristics, the dual-strategy hypothesis, and a kinematic model of movement trajectory. EMG patterns are considered emergent properties of hypothetical control patterns that are equally affected by the control signals and peripheral feedback reflecting actual movement trajectory. A computer model generated the EMG patterns based on simulated movement kinematics and hypothetical control signals derived from the reconstructed joint compliant characteristics. The model predictions have been compared to published recordings of movement kinematics and EMG patterns in a variety of movement conditions, including movements over different distances, at different speeds, against different-known inertial loads, and in conditions of possible unexpected decrease in the inertial load. Changes in task parameters within the model led to simulated EMG patterns qualitatively similar to the experimentally recorded EMG patterns. The model's predictive power compares it favourably to the existing models of the EMG patterns. Copyright © 1994. Published by Elsevier Ltd.

Ground reaction forces and knee kinetics during single and repeated badminton lunges.

PubMed

Lam, Wing Kai; Ding, Rui; Qu, Yi

2017-03-01

Repeated movement (RM) lunge that frequently executed in badminton might be used for footwear evaluation. This study examined the influence of single movement (SM) and RM lunges on the ground reaction forces (GRFs) and knee kinetics during the braking phase of a badminton lunge step. Thirteen male university badminton players performed left-forward lunges in both SM and RM sessions. Force platform and motion capturing system were used to measure GRFs and knee kinetics variables. Paired t-test was performed to determine any significant differences between SM and RM lunges regarding mean and coefficient of variation (CV) in each variable. The kinetics results indicated that compared to SM lunges, the RM lunges had shorter contact time and generated smaller maximum loading rate of impact force, peak knee anterior-posterior force, and peak knee sagittal moment but generated larger peak horizontal resultant forces (Ps < 0.05). Additionally, the RM lunges had lower CV for peak knee medial-lateral and vertical forces (Ps < 0.05). These results suggested that the RM testing protocols had a distinct loading response and adaptation pattern during lunge and that the RM protocol showed higher within-trial reliability, which may be beneficial for the knee joint loading evaluation under different interventions.

Evolution of altruism in spatial prisoner's dilemma: Intra- and inter-cellular interactions

NASA Astrophysics Data System (ADS)

Yokoi, Hiroki; Uehara, Takashi; Sakata, Tomoyuki; Naito, Hiromi; Morita, Satoru; Tainaka, Kei-ichi

2014-12-01

Iterated prisoner's dilemma game is carried out on lattice with “colony” structure. Each cell is regarded as a colony which contains plural players with an identical strategy. Both intra- and inter-cellular interactions are assumed. In the former a player plays with all other players in the same colony, while in the latter he plays with one player each from adjacent colonies. Spatial patterns among four typical strategies exhibit various dynamics and winners. Both theory and simulation reveal that All Cooperation (AC) wins, when the members of colony or the intensity of noise increases. This result explains the evolution of altruism in animal societies, even though errors easily occur in animal communications.

Dynamics of tactical behaviour in association football when manipulating players' space of interaction

PubMed Central

Torrents, Carlota; Gonçalves, Bruno; Torres-Ronda, Lorena; Sampaio, Jaime; Hristovski, Robert

2017-01-01

The analysis of positional data in association football allows the spatial distribution of players during matches to be described in order to improve the understanding of tactical-related constraints on the behavioural dynamics of players. The aim of this study was to identify how players’ spatial restrictions affected the exploratory tactical behaviour and constrained the perceptual-motor workspace of players in possession of the ball, as well as inter-player passing interactions. Nineteen professional outfield male players were divided into two teams of 10 and 9 players, respectively. The game was played under three spatial constraints: a) players were not allowed to move out of their allocated zones, except for the player in possession of the ball; b) players were allowed to move to an adjacent zone, and; c) non-specific spatial constraints. Positional data was captured using a 5 Hz interpolated GPS tracking system and used to define the configuration states of players for each second in time. The configuration state comprised 37 categories derived from tactical actions, distance from the nearest opponent, distance from the target and movement speed. Notational analysis of players in possession of the ball allowed the mean time of ball possession and the probabilities of passing the ball between players to be calculated. The results revealed that the players’ long-term exploratory behaviour decreased and their short-term exploration increased when restricting their space of interaction. Relaxing players’ positional constraints seemed to increase the speed of ball flow dynamics. Allowing players to move to an adjacent sub-area increased the probabilities of interaction with the full-back during play build-up. The instability of the coordinative state defined by being free from opponents when players had the ball possession was an invariant feature under all three task constraints. By allowing players to move to adjacent sub-areas, the coordinative state became highly unstable when the distance from the target decreased. Ball location relative to the scoring zone and interpersonal distance constitute key environmental information that constrains the players’ coordinative behaviour. Based on our results, dynamic overlap is presented as a good option to capture tactical performance. Moreover, the selected collective (i.e. relational) variables would allow coaches to identify the effects of training drills on teams and players’ behaviour. More research is needed considering these type variables to understand how the manipulation of constraints induce a more stable or flexible dynamical structure of tactical behaviour. PMID:28708868

Gender differences in game responses during badminton match play.

PubMed

Fernandez-Fernandez, Jaime; de la Aleja Tellez, Jose G; Moya-Ramon, Manuel; Cabello-Manrique, David; Mendez-Villanueva, Alberto

2013-09-01

The aim of this study was to evaluate possible gender differences in match play activity pattern [rally duration, rest time between rallies, effective playing time, and strokes performed during a rally] and exercise intensity (heart rate [HR], blood lactate [La], and subjective ratings of perceived exertion [RPE]) during 9 simulated badminton matches in male (n = 8) and female (n = 8) elite junior (16.0 ± 1.4 years) players. Results showed significant differences (all p < 0.05; effect size (ES) = 0.80-1.56) between male and female players in the activity pattern of match play, with male players engaged in longer rallies (6.8 ± 4.8 vs. 5.7 ± 3.1 seconds), executing more strokes per rally (6.4 ± 4.8 vs. 4.7 ± 2.8) and resting more between rallies (10.5 ± 8.8 vs. 8.8 ± 7.2 seconds) than female players. No clear differences (all p > 0.05; ES = -0.33 to 0.08) were observed between female or male players in average HR (174 ± 7 vs. 170 ± 9 b·min(-1)), %HRmax (89.2 ± 4.0% vs. 85.9 ± 4.3%), La (2.5 ± 1.3 vs. 3.2 ± 1.8 mmol·L(-1)), and RPE values (14.2 ± 1.9 vs. 14.6 ± 1.8) during match play, although male players spent more time (moderate effect sizes) at intensities between 81 and 90% HRmax (35.3 ± 17.9 vs. 25.3 ± 13.6; p < 0.05; ES = 0.64) in the second game. There seemed to be a trend toward an increased playing intensity (i.e., higher HR, La, and RPE) from the first to the second game, highlighting the higher exercise intensity experienced during the last part of the match. The clear between-gender differences in activity patterns induced only slightly different physiological responses.

Negative Influence of Motor Impairments on Upper Limb Movement Patterns in Children with Unilateral Cerebral Palsy. A Statistical Parametric Mapping Study

PubMed Central

Simon-Martinez, Cristina; Jaspers, Ellen; Mailleux, Lisa; Desloovere, Kaat; Vanrenterghem, Jos; Ortibus, Els; Molenaers, Guy; Feys, Hilde; Klingels, Katrijn

2017-01-01

Upper limb three-dimensional movement analysis (UL-3DMA) offers a reliable and valid tool to evaluate movement patterns in children with unilateral cerebral palsy (uCP). However, it remains unknown to what extent the underlying motor impairments explain deviant movement patterns. Such understanding is key to develop efficient rehabilitation programs. Although UL-3DMA has been shown to be a useful tool to assess movement patterns, it results in a multitude of data, challenging the clinical interpretation and consequently its implementation. UL-3DMA reports are often reduced to summary metrics, such as average or peak values per joint. However, these metrics do not take into account the continuous nature of the data or the interdependency between UL joints, and do not provide phase-specific information of the movement pattern. Moreover, summary metrics may not be sensitive enough to estimate the impact of motor impairments. Recently, Statistical Parametric Mapping (SPM) was proposed to overcome these problems. We collected UL-3DMA of 60 children with uCP and 60 typically developing children during eight functional tasks and evaluated the impact of spasticity and muscle weakness on UL movement patterns. SPM vector field analysis was used to analyze movement patterns at the level of five joints (wrist, elbow, shoulder, scapula, and trunk). Children with uCP showed deviant movement patterns in all joints during a large percentage of the movement cycle. Spasticity and muscle weakness negatively impacted on UL movement patterns during all tasks, which resulted in increased wrist flexion, elbow pronation and flexion, increased shoulder external rotation, decreased shoulder elevation with a preference for movement in the frontal plane and increased trunk internal rotation. Scapular position was altered during movement initiation, although scapular movements were not affected by muscle weakness or spasticity. In conclusion, we identified pathological movement patterns in children with uCP and additionally mapped the negative impact of spasticity and muscle weakness on these movement patterns, providing useful insights that will contribute to treatment planning. Last, we also identified a subset of the most relevant tasks for studying UL movements in children with uCP, which will facilitate the interpretation of UL-3DMA data and undoubtedly contribute to its clinical implementation. PMID:29051729

Drinking by professional Australian Football League (AFL) players: prevalence and correlates of risk.

PubMed

Dietze, Paul M; Fitzgerald, John L; Jenkinson, Rebecca A

2008-11-03

To examine self-reported patterns of alcohol consumption and experience of alcohol-related harms among professional Australian Football League (AFL) players. Cross-sectional survey of player alcohol consumption and self-reported alcohol-related harms among members of all 16 professional AFL clubs. Data relating to the 2006 football year were collected between 25 July and 30 August 2006 at regular football training sessions using a self-administered structured questionnaire. Risky/high-risk drinking for long- and short-term harm at different times of the year; Alcohol Use Disorders Identification Test (AUDIT) score. 582 AFL players completed the questionnaire (an 83% response rate). Alcohol consumption varied at different times of the year. During the playing season (approximately 22 weeks), the level of risky/high-risk consumption for long-term harm in AFL players (11/564 [2%]) was typically lower than in age-matched Australian men in the general population (15%). However, risky/high-risk consumption for long-term harm was higher in AFL players during the end-of-season period (approximately 2 weeks) (303/561 [54%]) and vacation period (6-8 weeks) (231/559 [41%]) than in age-matched Australian men. Risky/high-risk drinking for short-term harm on a monthly basis was frequent at all times of the year (eg, 395/560 [71%] in the pre-season period). The mean AUDIT score was 8.8 (95% CI, 8.4 to 9.1; range, 0 to 36). Reports of harmful effects of drinking and negative consequences, such as getting involved in a fight (physical or verbal) while drinking (146/556 [26%]), were common. Risky/high-risk consumption for short-term harm on a monthly basis was associated with a variety of player characteristics, such as usually drinking in public locations (odds ratio, 1.55 [95% CI, 1.02 to 2.35]). AUDIT score was associated with variables such as marital status, with married players scoring more than two points lower (95% CI, - 3.58 to - 0.58) than single players. Formal club rules on alcohol consumption had little effect on outcome measures. Drinking among AFL players is intricately related to time of year. This seasonal drinking pattern requires the development of specific club and league strategies to minimise drinking-related harms to players.

Revising superior planning performance in chess players: the impact of time restriction and motivation aspects.

PubMed

Unterrainer, Josef Martin; Kaller, Christoph Philipp; Leonhart, Rainer; Rahm, Benjamin

2011-01-01

In a previous study (Unterrainer, Kaller, Halsband, & Rahm, 2006), chess players outperformed non-chess players in the Tower of London planning task but exhibited disproportionately longer processing times. This pattern of results raises the question of whether chess players' planning capabilities are superior or whether the results reflect differences in the speed-accuracy trade-off between the groups, possibly attributable to sports motivation. The present study was designed to disambiguate these alternative suggestions by implementing various constraints on planning time and by assessing self-reported motivation. In contrast to the previous study, chess players' performance was not superior, independently of whether problems had to be solved with (Experiment 1) or without (Experiment 2) time limits. As expected, chess players reported higher overall trait and state motivation scores across both experiments. These findings revise the notion of superior planning performance in chess players. In consequence, they do not conform with the assumption of a general transfer of chess-related planning expertise to other cognitive domains, instead suggesting that superior performance may be possible only under specific circumstances such as receiving competitive instructions.

Long-term movement patterns of a coral reef predator

NASA Astrophysics Data System (ADS)

Heupel, M. R.; Simpfendorfer, C. A.

2015-06-01

Long-term monitoring is required to fully define periodicity and patterns in animal movement. This is particularly relevant for defining what factors are driving the presence, location, and movements of individuals. The long-term movement and space use patterns of grey reef sharks, Carcharhinus amblyrhynchos, were examined on a whole of reef scale in the southern Great Barrier Reef to define whether movement and activity space varied through time. Twenty-nine C. amblyrhynchos were tracked for over 2 years to define movement patterns. All individuals showed high residency within the study site, but also had high roaming indices. This indicated that individuals remained in the region and used all of the monitored habitat (i.e., the entire reef perimeter). Use of space was consistent through time with high reuse of areas most of the year. Therefore, individuals maintained discrete home ranges, but undertook broader movements around the reef at times. Mature males showed greatest variation in movement with larger activity spaces and movement into new regions during the mating season (August-September). Depth use patterns also differed, suggesting behaviour or resource requirements varied between sexes. Examination of the long-term, reef-scale movements of C. amblyrhynchos has revealed that reproductive activity may play a key role in space use and activity patterns. It was unclear whether mating behaviour or an increased need for food to sustain reproductive activity and development played a greater role in these patterns. Reef shark movement patterns are becoming more clearly defined, but research is still required to fully understand the biological drivers for the observed patterns.

Movement Pattern Variability in Stone Knapping: Implications for the Development of Percussive Traditions

PubMed Central

Rein, Robert; Nonaka, Tetsushi; Bril, Blandine

2014-01-01

The earliest direct evidence for tool-use by our ancestors are 2.6 million year old stone tools from Africa. These earliest artifacts show that, already, early hominins had developed the required advanced movement skills and cognitive capacities to manufacture stone tools. Currently, it is not well understood, however, which specific movement skills are required for successful stone knapping and accordingly it is unknown how these skills emerged during early hominin evolution. In particular, it is not clear which striking movements are indicative of skilled performance, how striking movement patterns vary with task and environmental constraints, and how movement patterns are passed on within social groups. The present study addresses these questions by investigating striking movement patterns and striking variability in 18 modern stone knappers (nine experienced and nine novices). The results suggest that no single movement pattern characterizes successful stone knapping. Participants showed large inter-individual movement variability of the elementary knapping action irrespective of knapping experience and knapping performance. Changes in task- and environmental constraints led knappers to adapt their elementary striking actions using a combination of individual and common strategies. Investigation of striking pattern similarities within social groups showed only partial overlap of striking patterns across related individuals. The results therefore suggest that striking movement patterns in modern stone knappers are largely specific to the individual and movement variability is not indicative of knapping performance. The implications of these results for the development of percussive traditions are discussed. PMID:25426630

Fatigue Responses in Various Muscle Groups in Well-Trained Competitive Male Players after a Simulated Soccer Game

PubMed Central

Fransson, Dan; Vigh-Larsen, Jeppe Foged; Fatouros, Ioannis G.; Krustrup, Peter; Mohr, Magni

2018-01-01

Abstract We examined the degree of post-game fatigue and the recovery pattern in various leg and upper-body muscle groups after a simulated soccer game. Well-trained competitive male soccer players (n = 12) participated in the study. The players completed the Copenhagen Soccer Test, a 2 x 45 min simulated soccer protocol, following baseline measures of maximal voluntary contractions of multiple muscle groups and systemic markers of muscle damage and inflammation at 0, 24 and 48 h into recovery. All muscle groups had a strength decrement (p ≤ 0.05) at 0 h post-match with knee flexors (14 ± 3%) and hip abductors (6 ± 1%) demonstrating the largest and smallest impairment. However, 24 h into recovery all individual muscles had recovered. When pooled in specific muscle groups, the trunk muscles and knee joint muscles presented the largest decline 0 h post-match, 11 ± 2% for both, with the performance decrement still persistent (4 ± 1%, p ≤ 0.05) for trunk muscles 24 h into recovery. Large inter-player variations were observed in game-induced fatigue and recovery patterns in the various muscle groups. Markers of muscle damage and inflammation peaked 0 h post-match (myoglobin) and 24 h into recovery (creatine kinase), respectively, but thereafter returned to baseline. Intermittent test performance correlated with creatine kinase activity 24 h after the Copenhagen Soccer Test (r = -0.70; p = 0.02). In conclusion, post-game fatigue is evident in multiple muscle groups with knee flexors showing the greatest performance decrement. Fatigue and recovery patterns vary markedly between muscle groups and players, yet trunk muscles display the slowest recovery. PMID:29599862

Fatigue Responses in Various Muscle Groups in Well-Trained Competitive Male Players after a Simulated Soccer Game.

PubMed

Fransson, Dan; Vigh-Larsen, Jeppe Foged; Fatouros, Ioannis G; Krustrup, Peter; Mohr, Magni

2018-03-01

We examined the degree of post-game fatigue and the recovery pattern in various leg and upper-body muscle groups after a simulated soccer game. Well-trained competitive male soccer players (n = 12) participated in the study. The players completed the Copenhagen Soccer Test, a 2 x 45 min simulated soccer protocol, following baseline measures of maximal voluntary contractions of multiple muscle groups and systemic markers of muscle damage and inflammation at 0, 24 and 48 h into recovery. All muscle groups had a strength decrement ( p ≤ 0.05) at 0 h post-match with knee flexors (14 ± 3%) and hip abductors (6 ± 1%) demonstrating the largest and smallest impairment. However, 24 h into recovery all individual muscles had recovered. When pooled in specific muscle groups, the trunk muscles and knee joint muscles presented the largest decline 0 h post-match, 11 ± 2% for both, with the performance decrement still persistent (4 ± 1%, p ≤ 0.05) for trunk muscles 24 h into recovery. Large inter-player variations were observed in game-induced fatigue and recovery patterns in the various muscle groups. Markers of muscle damage and inflammation peaked 0 h post-match (myoglobin) and 24 h into recovery (creatine kinase), respectively, but thereafter returned to baseline. Intermittent test performance correlated with creatine kinase activity 24 h after the Copenhagen Soccer Test (r = -0.70; p = 0.02). In conclusion, post-game fatigue is evident in multiple muscle groups with knee flexors showing the greatest performance decrement. Fatigue and recovery patterns vary markedly between muscle groups and players, yet trunk muscles display the slowest recovery.

Tales of the Unexpected: Coping among Female Collegiate Volleyball Players

ERIC Educational Resources Information Center

Holt, Nicholas L.; Berg, Kylie-Joy; Tamminen, Katherine A.

2007-01-01

The purpose of this study was to examine patterns of appraisal, coping, and coping effectiveness in sport. Ten players from a collegiate female volleyball team were interviewed on two occasions, first in the week before a provincial final playoff tournament and in the week following the tournament. Data were transcribed verbatim and subjected to…

Player Preferences and Social Harm: An Analysis of the Relationships between Player Characteristics, Gambling Modes, and Problem Gambling

ERIC Educational Resources Information Center

Young, Martin; Stevens, Matthew

2009-01-01

To explore the structure of gambling participation and its association with problem gambling, we draw upon Caillois's distinction between games based on competition (i.e. "agon") and those based on chance (i.e. "alea"). The idea that "alea" and "agon" are socially patterned and associated with differing…

What Skills and Tactics Are Needed to Play Adult Pick-Up Basketball Games?

ERIC Educational Resources Information Center

Wang, Jianyu; Liu, Wenhao; Moffit, Jeffrey

2010-01-01

The purpose of this study was to examine skill levels and performance patterns of regular players of pick-up basketball games. By a survey, 65 participants were identified as regular players and participated in the study. An observational instrument used to analyze game performance of the participants was developed and both content and construct…

Recall of briefly presented chess positions and its relation to chess skill.

PubMed

Gong, Yanfei; Ericsson, K Anders; Moxley, Jerad H

2015-01-01

Individual differences in memory performance in a domain of expertise have traditionally been accounted for by previously acquired chunks of knowledge and patterns. These accounts have been examined experimentally mainly in chess. The role of chunks (clusters of chess pieces recalled in rapid succession during recall of chess positions) and their relations to chess skill are, however, under debate. By introducing an independent chunk-identification technique, namely repeated-recall technique, this study identified individual chunks for particular chess players. The study not only tested chess players with increasing chess expertise, but also tested non-chess players who should not have previously acquired any chess related chunks in memory. For recall of game positions significant differences between players and non-players were found in virtually all the characteristics of chunks recalled. Size of the largest chunks also correlates with chess skill within the group of rated chess players. Further research will help us understand how these memory encodings can explain large differences in chess skill.

Recall of Briefly Presented Chess Positions and Its Relation to Chess Skill

PubMed Central

Moxley, Jerad H.

2015-01-01

Individual differences in memory performance in a domain of expertise have traditionally been accounted for by previously acquired chunks of knowledge and patterns. These accounts have been examined experimentally mainly in chess. The role of chunks (clusters of chess pieces recalled in rapid succession during recall of chess positions) and their relations to chess skill are, however, under debate. By introducing an independent chunk-identification technique, namely repeated-recall technique, this study identified individual chunks for particular chess players. The study not only tested chess players with increasing chess expertise, but also tested non-chess players who should not have previously acquired any chess related chunks in memory. For recall of game positions significant differences between players and non-players were found in virtually all the characteristics of chunks recalled. Size of the largest chunks also correlates with chess skill within the group of rated chess players. Further research will help us understand how these memory encodings can explain large differences in chess skill. PMID:25774693

Relationship Between Motor Variability, Accuracy, and Ball Speed in the Tennis Serve

PubMed Central

Antúnez, Ruperto Menayo; Hernández, Francisco Javier Moreno; García, Juan Pedro Fuentes; Vaíllo, Raúl Reina; Arroyo, Jesús Sebastián Damas

2012-01-01

The main objective of this study was to analyze the motor variability in the performance of the tennis serve and its relationship to performance outcome. Seventeen male tennis players took part in the research, and they performed 20 serves. Linear and non-linear variability during the hand movement was measured by 3D Motion Tracking. Ball speed was recorded with a sports radar gun and the ball bounces were video recorded to calculate accuracy. The results showed a relationship between the amount of variability and its non-linear structure found in performance of movement and the outcome of the serve. The study also found that movement predictability correlates with performance. An increase in the amount of movement variability could affect the tennis serve performance in a negative way by reducing speed and accuracy of the ball. PMID:23486998

Associations between tongue movement pattern consistency and formant movement pattern consistency in response to speech behavioral modificationsa)

PubMed Central

Mefferd, Antje S.

2016-01-01

The degree of speech movement pattern consistency can provide information about speech motor control. Although tongue motor control is particularly important because of the tongue's primary contribution to the speech acoustic signal, capturing tongue movements during speech remains difficult and costly. This study sought to determine if formant movements could be used to estimate tongue movement pattern consistency indirectly. Two age groups (seven young adults and seven older adults) and six speech conditions (typical, slow, loud, clear, fast, bite block speech) were selected to elicit an age- and task-dependent performance range in tongue movement pattern consistency. Kinematic and acoustic spatiotemporal indexes (STI) were calculated based on sentence-length tongue movement and formant movement signals, respectively. Kinematic and acoustic STI values showed strong associations across talkers and moderate to strong associations for each talker across speech tasks; although, in cases where task-related tongue motor performance changes were relatively small, the acoustic STI values were poorly associated with kinematic STI values. These findings suggest that, depending on the sensitivity needs, formant movement pattern consistency could be used in lieu of direct kinematic analysis to indirectly examine speech motor control. PMID:27908069

Effects of Strength Training Combined with Specific Plyometric exercises on body composition, vertical jump height and lower limb strength development in elite male handball players: a case study.

PubMed

Carvalho, Alberto; Mourão, Paulo; Abade, Eduardo

2014-06-28

The purpose of the present study was to identify the effects of a strength training program combined with specific plyometric exercises on body composition, vertical jump (VJ) height and strength development of lower limbs in elite male handball players. A 12-week program with combined strength and specific plyometric exercises was carried out for 7 weeks. Twelve elite male handball players (age: 21.6 ± 1.73) competing in the Portuguese Major League participated in the study. Besides the anthropometric measurements, several standardized jump tests were applied to assess VJ performance together with the strength development of the lower limbs in an isokinetic setting. No significant changes were found in body circumferences and diameters. Body fat content and fat mass decreased by 16.4 and 15.7% respectively, while lean body mass increased by 2.1%. Despite small significance, there was in fact an increase in squat jump (SJ), counter movement jump (CMJ) and 40 consecutive jumps after the training period (6.1, 3.8 and 6.8%, respectively). After the applied protocol, peak torque increased in lower limb extension and flexion in the majority of the movements assessed at 90ºs-1. Consequently, it is possible to conclude that combining general strength-training with plyometric exercises can not only increase lower limb strength and improve VJ performance but also reduce body fat content.

Effects of Strength Training Combined with Specific Plyometric exercises on body composition, vertical jump height and lower limb strength development in elite male handball players: a case study

PubMed Central

Carvalho, Alberto; Mourão, Paulo; Abade, Eduardo

2014-01-01

The purpose of the present study was to identify the effects of a strength training program combined with specific plyometric exercises on body composition, vertical jump (VJ) height and strength development of lower limbs in elite male handball players. A 12-week program with combined strength and specific plyometric exercises was carried out for 7 weeks. Twelve elite male handball players (age: 21.6 ± 1.73) competing in the Portuguese Major League participated in the study. Besides the anthropometric measurements, several standardized jump tests were applied to assess VJ performance together with the strength development of the lower limbs in an isokinetic setting. No significant changes were found in body circumferences and diameters. Body fat content and fat mass decreased by 16.4 and 15.7% respectively, while lean body mass increased by 2.1%. Despite small significance, there was in fact an increase in squat jump (SJ), counter movement jump (CMJ) and 40 consecutive jumps after the training period (6.1, 3.8 and 6.8%, respectively). After the applied protocol, peak torque increased in lower limb extension and flexion in the majority of the movements assessed at 90ºs-1. Consequently, it is possible to conclude that combining general strength-training with plyometric exercises can not only increase lower limb strength and improve VJ performance but also reduce body fat content. PMID:25114739

The ingestion of a caffeinated energy drink improves jump performance and activity patterns in elite badminton players.

PubMed

Abian, Pablo; Del Coso, Juan; Salinero, Juan José; Gallo-Salazar, Cesar; Areces, Francisco; Ruiz-Vicente, Diana; Lara, Beatriz; Soriano, Lidon; Muñoz, Victor; Abian-Vicen, Javier

2015-01-01

The aim of this study was to investigate the effectiveness of a caffeine-containing energy drink to enhance physical and match performance in elite badminton players. Sixteen male and elite badminton players (25.4 ± 7.3 year; 71.8 ± 7.9 kg) participated in a double-blind, placebo-controlled and randomised experiment. On two different sessions, badminton players ingested 3 mg of caffeine per kg of body mass in the form of an energy drink or the same drink without caffeine (placebo). After 60 min, participants performed the following tests: handgrip maximal force production, smash jump without and with shuttlecock, squat jump, countermovement jump and the agility T-test. Later, a 45-min simulated badminton match was played. Players' number of impacts and heart rate was measured during the match. The ingestion of the caffeinated energy drink increased squat jump height (34.5 ± 4.7 vs. 36.4 ± 4.3 cm; P < 0.05), squat jump peak power (P < 0.05), countermovement jump height (37.7 ± 4.5 vs. 39.5 ± 5.1 cm; P < 0.05) and countermovement jump peak power (P < 0.05). In addition, an increased number of total impacts was found during the badminton match (7395 ± 1594 vs. 7707 ± 2033 impacts; P < 0.05). In conclusion, the results show that the use of caffeine-containing energy drink may be an effective nutritional aid to increase jump performance and activity patterns during game in elite badminton players.

Little AI: Playing a constructivist robot

NASA Astrophysics Data System (ADS)

Georgeon, Olivier L.

Little AI is a pedagogical game aimed at presenting the founding concepts of constructivist learning and developmental Artificial Intelligence. It primarily targets students in computer science and cognitive science but it can also interest the general public curious about these topics. It requires no particular scientific background; even children can find it entertaining. Professors can use it as a pedagogical resource in class or in online courses. The player presses buttons to control a simulated "baby robot". The player cannot see the robot and its environment, and initially ignores the effects of the commands. The only information received by the player is feedback from the player's commands. The player must learn, at the same time, the functioning of the robot's body and the structure of the environment from patterns in the stream of commands and feedback. We argue that this situation is analogous to how infants engage in early-stage developmental learning (e.g., Piaget (1937), [1]).

Hypoconnectivity and hyperfrontality in retired American football players.

PubMed

Hampshire, Adam; MacDonald, Alex; Owen, Adrian M

2013-10-17

Recent research has raised concerns about the long-term neurological consequences of repetitive concussive and sub-concussive injuries in professional players of American Football. Despite this interest, the neural and psychological status of retired players remains unknown. Here, we evaluated the performances and brain activation patterns of retired National Football League players (NFL alumni) relative to controls using an fMRI-optimised neuropsychological test of executive function. Behaviourally, the NFL alumni showed only modest performance deficits on the executive task. By contrast, they showed pronounced hyperactivation and hypoconnectivity of the dorsolateral frontal and frontopolar cortices. Critically, abnormal frontal-lobe function was correlated with the number of times that NFL alumni reported having been removed from play after head injury and was evident in individual players. These results support the hypothesis that NFL alumni have a heightened probability of developing executive dysfunction and suggest that fMRI provides the most sensitive biomarker of the underlying neural abnormality.

Hypoconnectivity and Hyperfrontality in Retired American Football Players

NASA Astrophysics Data System (ADS)

Hampshire, Adam; MacDonald, Alex; Owen, Adrian M.

2013-10-01

Recent research has raised concerns about the long-term neurological consequences of repetitive concussive and sub-concussive injuries in professional players of American Football. Despite this interest, the neural and psychological status of retired players remains unknown. Here, we evaluated the performances and brain activation patterns of retired National Football League players (NFL alumni) relative to controls using an fMRI-optimised neuropsychological test of executive function. Behaviourally, the NFL alumni showed only modest performance deficits on the executive task. By contrast, they showed pronounced hyperactivation and hypoconnectivity of the dorsolateral frontal and frontopolar cortices. Critically, abnormal frontal-lobe function was correlated with the number of times that NFL alumni reported having been removed from play after head injury and was evident in individual players. These results support the hypothesis that NFL alumni have a heightened probability of developing executive dysfunction and suggest that fMRI provides the most sensitive biomarker of the underlying neural abnormality.

On the complexity of classical guitar playing: functional adaptations to task constraints.

PubMed

Heijink, Hank; Meulenbroek, Ruud G J

2002-12-01

The authors performed a behavioral study of the complexity of left-hand finger movements in classical guitar playing. Six professional guitarists played movement sequences in a fixed tempo. Left-hand finger movements were recorded in 3 dimensions, and the guitar sound was recorded synchronously. Assuming that performers prefer to avoid extreme joint angles when moving, the authors hypothesized 3 complexity factors. The results showed differential effects of the complexity factors on the performance measures and on participants' judgments of complexity. The results demonstrated that keeping the joints in the middle of their range is an important principle in guitar playing, and players exploit the available tolerance in timing and placement of the left-hand fingers to control the acoustic output variability.

Increasing motivation in robot-aided arm rehabilitation with competitive and cooperative gameplay

PubMed Central

2014-01-01

Background Several strategies have been proposed to improve patient motivation and exercise intensity during robot-aided stroke rehabilitation. One relatively unexplored possibility is two-player gameplay, allowing subjects to compete or cooperate with each other to achieve a common goal. In order to explore the potential of such games, we designed a two-player game played using two ARMin arm rehabilitation robots. Methods The game was an air-hockey task displayed on a computer monitor and controlled using shoulder movements in the ARMin robot. Three game modes were tested: single-player (competing against computer), competitive (competing against human), and cooperative (cooperating with human against computer). All modes were played by 30 unimpaired subjects and 8 impaired chronic stroke subjects. The subjects filled out the Intrinsic Motivation Inventory questionnaire after each game mode, as well as a final questionnaire about game preferences and their personality. Results Nearly all unimpaired subjects preferred playing the two-player game modes to the single-player one, as they enjoyed talking and interacting with another person. However, there were two distinct player groups: one liked the competitive mode but not the cooperative mode while the other liked the cooperative but not the competitive mode. Unimpaired subjects who liked the competitive mode also put significantly more effort into it than into the other modes. Results from impaired subjects were similar, with even impaired subjects over 60 years old enjoying competitive gameplay. The subjects’ personalities roughly predicted which mode they would prefer, which was especially evident in a poorly-matched impaired pair that preferred the single-player mode. Conclusions Results indicate great potential for two-player rehabilitation games, in the form of greater enjoyment as well as potentially more intensive exercise compared to single-player games. However, the right game type needs to be chosen for each subject depending on skill and personality, along with selecting an appropriate co-player. Further studies with patients that are currently enrolled in rehabilitation programs are recommended, and the subjective measures used in our study should be augmented with objective measures such as electromyography. PMID:24739255

Increasing motivation in robot-aided arm rehabilitation with competitive and cooperative gameplay.

PubMed

Novak, Domen; Nagle, Aniket; Keller, Urs; Riener, Robert

2014-04-16

Several strategies have been proposed to improve patient motivation and exercise intensity during robot-aided stroke rehabilitation. One relatively unexplored possibility is two-player gameplay, allowing subjects to compete or cooperate with each other to achieve a common goal. In order to explore the potential of such games, we designed a two-player game played using two ARMin arm rehabilitation robots. The game was an air-hockey task displayed on a computer monitor and controlled using shoulder movements in the ARMin robot. Three game modes were tested: single-player (competing against computer), competitive (competing against human), and cooperative (cooperating with human against computer). All modes were played by 30 unimpaired subjects and 8 impaired chronic stroke subjects. The subjects filled out the Intrinsic Motivation Inventory questionnaire after each game mode, as well as a final questionnaire about game preferences and their personality. Nearly all unimpaired subjects preferred playing the two-player game modes to the single-player one, as they enjoyed talking and interacting with another person. However, there were two distinct player groups: one liked the competitive mode but not the cooperative mode while the other liked the cooperative but not the competitive mode. Unimpaired subjects who liked the competitive mode also put significantly more effort into it than into the other modes. Results from impaired subjects were similar, with even impaired subjects over 60 years old enjoying competitive gameplay. The subjects' personalities roughly predicted which mode they would prefer, which was especially evident in a poorly-matched impaired pair that preferred the single-player mode. Results indicate great potential for two-player rehabilitation games, in the form of greater enjoyment as well as potentially more intensive exercise compared to single-player games. However, the right game type needs to be chosen for each subject depending on skill and personality, along with selecting an appropriate co-player. Further studies with patients that are currently enrolled in rehabilitation programs are recommended, and the subjective measures used in our study should be augmented with objective measures such as electromyography.

Comparison of Ball-And-Racket Impact Force in Two-Handed Backhand Stroke Stances for Different-Skill-Level Tennis Players.

PubMed

Lo, Kuo-Cheng; Hsieh, Yung-Chun

2016-06-01

This study compared the kinetic roles of the upper extremities in racket impact force generation between the open stance (OS) and square stance (SS) for tennis players with different skill levels in two-handed backhand strokes. Twelve male tennis players were divided into an advanced group (AG) (L3-L2 skill level) and intermediate group (IG) (L7-L6 skill level), and their data were used in a three-dimensional kinetic analysis. Their motions were captured using 21 reflective markers attached to anatomic landmarks for two-handed backhand stroke motion data collection. During the acceleration phase, significant differences were not observed between both stances, but they were observed between the groups with different skill levels for the force of the upper extremities (p = 0.027). The joint forces were significantly lower in the AG than in the IG. Players performing the SS had significantly larger pronation and supination of the wrist joint moment than those in the OS (p = 0.032) during the acceleration phase, irrespective of the playing level. Higher internal rotation moment after impact was observed at each joint, particularly among young intermediate tennis players, regardless of their stance. The AG demonstrated a higher joint force and moment at every joint compared with the IG at impact. Moreover, the AG demonstrated superior stroke efficiency and effectively reduced joint moment after impact and sports injury. Key pointsAdvanced players, regardless of open stance or square stance, have larger joint force and moment at each joint before ball impact resulting in better stroke efficiency and reduced chance of injury.Intermediate players, regardless of stance, have higher internal rotation moment at each joint instead of larger joint force as compared to advanced players before ball impact. The higher internal rotation moment will induce higher joint impact force which makes the player injury-prone.Young intermediate tennis players may want to avoid excessive follow-through movement after ball impact to prevent injury in their early career.

The Overarm-Throwing Pattern among U-14 ASA Female Softball Players: A Comparative Study of Gender, Culture, and Experience

ERIC Educational Resources Information Center

Petranek, Laura Jones; Barton, Gina V.

2011-01-01

A developmental description of overarm-throwing characteristics of U-14 female ASA softball players is presented here. Comparisons were made between these athletes and teens of similar age in the United States (Runion, Roberton, & Langendorfer, 2003) and in Germany (Ehl, Roberton, & Langendorfer, 2005). A majority of the softball players…

The Endpoint Hypothesis: A Topological-Cognitive Assessment of Geographic Scale Movement Patterns

NASA Astrophysics Data System (ADS)

Klippel, Alexander; Li, Rui

Movement patterns of individual entities at the geographic scale are becoming a prominent research focus in spatial sciences. One pertinent question is how cognitive and formal characterizations of movement patterns relate. In other words, are (mostly qualitative) formal characterizations cognitively adequate? This article experimentally evaluates movement patterns that can be characterized as paths through a conceptual neighborhood graph, that is, two extended spatial entities changing their topological relationship gradually. The central questions addressed are: (a) Do humans naturally use topology to create cognitive equivalent classes, that is, is topology the basis for categorizing movement patterns spatially? (b) Are ‘all’ topological relations equally salient, and (c) does language influence categorization. The first two questions are addressed using a modification of the endpoint hypothesis stating that: movement patterns are distinguished by the topological relation they end in. The third question addresses whether language has an influence on the classification of movement patterns, that is, whether there is a difference between linguistic and non-linguistic category construction. In contrast to our previous findings we were able to document the importance of topology for conceptualizing movement patterns but also reveal differences in the cognitive saliency of topological relations. The latter aspect calls for a weighted conceptual neighborhood graph to cognitively adequately model human conceptualization processes.

Catastrophic rugby injuries of the spinal cord: changing patterns of injury.

PubMed Central

Scher, A T

1991-01-01

In reports from the UK and New Zealand, it is noted that the incidence of rugby injuries to the cervical spinal cord has dropped and that the percentage of players injured in the tackle has similarly decreased. In contrast, this does not appear to be the pattern in South Africa and an analysis has therefore been made of 40 rugby players sustaining injuries to the spinal cord during the period 1985 to 1989. The radiological appearances on admission have been correlated with the circumstances of injury, associated orthopaedic injuries and neurological deficits. The tackle was responsible for the majority of injuries, causing more than the scrum. Tackles were also responsible for more cases of complete, permanent quadriplegia than the scrum. The commonest cause of injury in players being tackled was the high tackle around the neck, while the commonest cause of injury in players making the tackle was the dive tackle. This survey has shown that the tackle is now the major cause of spinal cord injury in South African rugby, in contrast to earlier analyses in which the scrum was identified as the most common cause. Images Figure 1 Figure 2 PMID:1913034

Creating Time: Social Collaboration in Music Improvisation.

PubMed

Walton, Ashley E; Washburn, Auriel; Langland-Hassan, Peter; Chemero, Anthony; Kloos, Heidi; Richardson, Michael J

2018-01-01

Musical collaboration emerges from the complex interaction of environmental and informational constraints, including those of the instruments and the performance context. Music improvisation in particular is more like everyday interaction in that dynamics emerge spontaneously without a rehearsed score or script. We examined how the structure of the musical context affords and shapes interactions between improvising musicians. Six pairs of professional piano players improvised with two different backing tracks while we recorded both the music produced and the movements of their heads, left arms, and right arms. The backing tracks varied in rhythmic and harmonic information, from a chord progression to a continuous drone. Differences in movement coordination and playing behavior were evaluated using the mathematical tools of complex dynamical systems, with the aim of uncovering the multiscale dynamics that characterize musical collaboration. Collectively, the findings indicated that each backing track afforded the emergence of different patterns of coordination with respect to how the musicians played together, how they moved together, as well as their experience collaborating with each other. Additionally, listeners' experiences of the music when rating audio recordings of the improvised performances were related to the way the musicians coordinated both their playing behavior and their bodily movements. Accordingly, the study revealed how complex dynamical systems methods (namely recurrence analysis) can capture the turn-taking dynamics that characterized both the social exchange of the music improvisation and the sounds of collaboration more generally. The study also demonstrated how musical improvisation provides a way of understanding how social interaction emerges from the structure of the behavioral task context. Copyright © 2017 Cognitive Science Society, Inc.

Associations Between Rate of Force Development Metrics and Throwing Velocity in Elite Team Handball Players: a Short Research Report

PubMed Central

Marques, Mário C.; Saavedra, Francisco J.; Abrantes, Catarina; Aidar, Felipe J.

2011-01-01

Performance assessment has become an invaluable component of monitoring participant’s development in distinct sports, yet limited and contradictory data are available in trained subjects. The purpose of this study was to examine the relationship between ball throwing velocity during a 3-step running throw in elite team handball players and selected measures of rate of force development like force, power, velocity, and bar displacement during a concentric only bench press exercise in elite male handball players. Fitteen elite senior male team handball players volunteered to participate. Each volunteer had power and bar velocity measured during a concentric only bench press test with 25, 35, and 45 kg as well as having one-repetition maximum strength determined. Ball throwing velocity was evaluated with a standard 3-step running throw using a radar gun. The results of this study indicated significant associations between ball velocity and time at maximum rate of force development (0, 66; p<0.05) and rate of force development at peak force (0,56; p<0.05) only with 25kg load. The current research indicated that ball velocity was only median associated with maximum rate of force development with light loads. A training regimen designed to improve ball-throwing velocity in elite male team handball players should emphasize bench press movement using light loads. PMID:23487363

Sensitivity of monthly heart rate and psychometric measures for monitoring physical performance in highly trained young handball players.

PubMed

Buchheit, M

2015-05-01

The aim of the present study was to examine whether monthly resting heart rate (HR), HR variability (HRV) and psychometric measures can be used to monitor changes in physical performance in highly-trained adolescent handball players. Data were collected in 37 adolescent players (training 10±2.1 h.wk(-1)) on 11 occasions from September to May during the in-season period, and included an estimation of training status (resting HR and HRV, the profile of mood state (POMS) questionnaire), and 3 physical performance tests (a 10-m sprint, a counter movement jump and a graded aerobic intermittent test, 30-15 Intermittent Fitness Test). The sensitivity of HR and psychometric measures to changes in physical performance was poor (< 20%), irrespective of the training status markers and the performance measures. The specificity was however strong (> 75%), irrespective of the markers and the performance measures. Finally, the difference in physical performance between players with better vs. worse estimated training status were all almost certainly trivial. The present results highlight the limitation of monthly measures of resting HR, HRV and perceived mood and fatigue for predicting in-season changes in physical performance in highly-trained adolescent handball players. This suggests that more frequent monitoring might be required, and/or that other markers might need to be considered. © Georg Thieme Verlag KG Stuttgart · New York.

Associations between rate of force development metrics and throwing velocity in elite team handball players: a short research report.

PubMed

Marques, Mário C; Saavedra, Francisco J; Abrantes, Catarina; Aidar, Felipe J

2011-09-01

Performance assessment has become an invaluable component of monitoring participant's development in distinct sports, yet limited and contradictory data are available in trained subjects. The purpose of this study was to examine the relationship between ball throwing velocity during a 3-step running throw in elite team handball players and selected measures of rate of force development like force, power, velocity, and bar displacement during a concentric only bench press exercise in elite male handball players. Fitteen elite senior male team handball players volunteered to participate. Each volunteer had power and bar velocity measured during a concentric only bench press test with 25, 35, and 45 kg as well as having one-repetition maximum strength determined. Ball throwing velocity was evaluated with a standard 3-step running throw using a radar gun. The results of this study indicated significant associations between ball velocity and time at maximum rate of force development (0, 66; p<0.05) and rate of force development at peak force (0,56; p<0.05) only with 25kg load. The current research indicated that ball velocity was only median associated with maximum rate of force development with light loads. A training regimen designed to improve ball-throwing velocity in elite male team handball players should emphasize bench press movement using light loads.

HIP AND GLENOHUMERAL PASSIVE RANGE OF MOTION IN COLLEGIATE SOFTBALL PLAYERS

PubMed Central

Plummer, Hillary; Brambeck, Allison

2016-01-01

Background and Purpose Range of motion deficits at the hip and glenohumeral joint (GHJ) may contribute to the incidence of injury in softball players. With injury in softball players on the rise, softball related studies in the literature are important. The purpose of this study was to examine hip and GHJ passive range of motion (PROM) patterns in collegiate softball players. Hypothesis It was hypothesized that the position players would exhibit significantly different PROM patterns than pitchers. Additionally, position players would exhibit significantly different side-to-side differences in PROM for both the hip and GHJ compared to pitchers. Study Design Prospective cohort study. Methods Forty-nine collegiate softball players (19.63 ± 1.15 years; 170.88 ± 8.08 cm; 72.96 ± 19.41 kg) participated. Passive hip and GHJ internal (IR) and external rotation (ER) measures were assessed. Glenohumeral PROM was measured with the participants supine with the arm abducted to 90 °. The measurements were recorded when the scapula began to move or a firm capsular end-feel was achieved. The hip was positioned in 90 ° of flexion and passively rotated until a capsular end-feel was achieved. Total PROM was calculated by taking the sum of IR and ER for both the hip and GHJ. Results No significant side-to-side PROM differences were observed in pitchers, at the GHJ or hip joint. Position players throwing side hip IR was significantly greater than the non-throwing side hip (p = 0.002). The non-throwing side hip had significantly greater ER compared to the throwing side hip (p = 0.002). When examining side-to-side differences at the GHJ, IR was significantly greater in the non-throwing shoulder (p = 0.047). No significant differences in total range of motion of the hip and GHJ were observed. Conclusion In the current study, position players displayed side-to-side differences in hip and GHJ IR PROM while no statistically significant differences were observed in the softball pitchers. The findings of the current study add to the body of literature related to PROM in throwing athletes, additionally these are the first hip IR and ER PROM data presented in softball players. Level of Evidence Level 3 PMID:27757286

Stimulus generalization as a mechanism for learning to trust

PubMed Central

FeldmanHall, Oriel; Dunsmoor, Joseph E.; Tompary, Alexa; Hunter, Lindsay E.; Todorov, Alexander; Phelps, Elizabeth A.

2018-01-01

How do humans learn to trust unfamiliar others? Decisions in the absence of direct knowledge rely on our ability to generalize from past experiences and are often shaped by the degree of similarity between prior experience and novel situations. Here, we leverage a stimulus generalization framework to examine how perceptual similarity between known individuals and unfamiliar strangers shapes social learning. In a behavioral study, subjects play an iterative trust game with three partners who exhibit highly trustworthy, somewhat trustworthy, or highly untrustworthy behavior. After learning who can be trusted, subjects select new partners for a second game. Unbeknownst to subjects, each potential new partner was parametrically morphed with one of the three original players. Results reveal that subjects prefer to play with strangers who implicitly resemble the original player they previously learned was trustworthy and avoid playing with strangers resembling the untrustworthy player. These decisions to trust or distrust strangers formed a generalization gradient that converged toward baseline as perceptual similarity to the original player diminished. In a second imaging experiment we replicate these behavioral gradients and leverage multivariate pattern similarity analyses to reveal that a tuning profile of activation patterns in the amygdala selectively captures increasing perceptions of untrustworthiness. We additionally observe that within the caudate adaptive choices to trust rely on neural activation patterns similar to those elicited when learning about unrelated, but perceptually familiar, individuals. Together, these findings suggest an associative learning mechanism efficiently deploys moral information encoded from past experiences to guide future choice. PMID:29378964

Discovering loose group movement patterns from animal trajectories

USGS Publications Warehouse

Wang, Yuwei; Luo, Ze; Xiong, Yan; Prosser, Diann J.; Newman, Scott H.; Takekawa, John Y.; Yan, Baoping

2015-01-01

The technical advances of positioning technologies enable us to track animal movements at finer spatial and temporal scales, and further help to discover a variety of complex interactive relationships. In this paper, considering the loose gathering characteristics of the real-life groups' members during the movements, we propose two kinds of loose group movement patterns and corresponding discovery algorithms. Firstly, we propose the weakly consistent group movement pattern which allows the gathering of a part of the members and individual temporary leave from the whole during the movements. To tolerate the high dispersion of the group at some moments (i.e. to adapt the discontinuity of the group's gatherings), we further scheme the weakly consistent and continuous group movement pattern. The extensive experimental analysis and comparison with the real and synthetic data shows that the group pattern discovery algorithms proposed in this paper are similar to the the real-life frequent divergences of the members during the movements, can discover more complete memberships, and have considerable performance.

Nutritional Status and Daytime Pattern of Protein Intake on Match, Post-Match, Rest and Training Days in Senior Professional and Youth Elite Soccer Players.

PubMed

Bettonviel A, E O; Brinkmans N, Y J; Russcher, Kris; Wardenaar, Floris C; Witard, Oliver C

2016-06-01

The nutritional status of elite soccer players across match, postmatch, training and rest days has not been defined. Recent evidence suggests the pattern of dietary protein intake impacts the daytime turnover of muscle proteins and, as such, influences muscle recovery. We assessed the nutritional status and daytime pattern of protein intake in senior professional and elite youth soccer players and compared findings against published recommendations. Fourteen senior professional (SP) and 15 youth elite (YP) soccer players from the Dutch premier division completed nutritional assessments using a 24-hr web-based recall method. Recall days consisted of a match, postmatch, rest, and training day. Daily energy intake over the 4-day period was similar between SP (2988 ± 583 kcal/day) and YP (2938 ± 465 kcal/day; p = .800). Carbohydrate intake over the combined 4-day period was lower in SP (4.7 ± 0.7 g·kg-1 BM·day-1) vs. YP (6.0 ± 1.5 g·kg-1 BM·day-1, p = .006) and SP failed to meet recommended carbohydrate intakes on match and training days. Conversely, recommended protein intakes were met for SP (1.9 ± 0.3 g·kg-1 BM·day-1) and YP (1.7 ± 0.4 g·kg-1 BM·day-1), with no differences between groups (p = .286). Accordingly, both groups met or exceeded recommended daily protein intakes on individual match, postmatch, rest and training days. A similar "balanced" daytime pattern of protein intake was observed in SP and YP. To conclude, SP increased protein intake on match and training days to a greater extent than YP, however at the expense of carbohydrate intake. The daytime distribution of protein intake for YP and SP aligned with current recommendations of a balanced protein meal pattern.

Set as an instance of a real-world visual-cognitive task.

PubMed

Nyamsuren, Enkhbold; Taatgen, Niels A

2013-01-01

Complex problem solving is often an integration of perceptual processing and deliberate planning. But what balances these two processes, and how do novices differ from experts? We investigate the interplay between these two in the game of SET. This article investigates how people combine bottom-up visual processes and top-down planning to succeed in this game. Using combinatorial and mixed-effect regression analysis of eye-movement protocols and a cognitive model of a human player, we show that SET players deploy both bottom-up and top-down processes in parallel to accomplish the same task. The combination of competition and cooperation of both types of processes is a major factor of success in the game. Finally, we explore strategies players use during the game. Our findings suggest that within-trial strategy shifts can occur without the need of explicit meta-cognitive control, but rather implicitly as a result of evolving memory activations. Copyright © 2012 Cognitive Science Society, Inc.

Torque-angle-velocity Relationships and Muscle Performance of Professional and Youth Soccer Players.

PubMed

Mazuquin, B F; Dela Bela, L F; Pelegrinelli, A R M; Dias, J M; Carregaro, R L; Moura, F A; Selfe, J; Richards, J; Brown, L E; Cardoso, J R

2016-11-01

Soccer matches consist of a variety of different activities, including repeated sprints. Time to attain velocity (TTAV), load range (LR) and the torque-angle-velocity relationship (TAV 3D ) represent an important measurement of muscle performance, however there are few related studies. The aim of this study was to compare these outcomes between soccer players of different age category. 17 professional (PRO) and 17 under-17 (U17) soccer players were assessed for concentric knee flexion/extension at 60, 120 and 300°/s. For the extensor muscles, differences were found in favor of the U17 group for TTAV and LR outcomes at 120°/s, however, the PRO group maintained higher torques in both movement directions in comparison to the U17 in TAV 3D evaluation. These results suggest that muscle performance of the PRO group is more efficient than the U17 group. © Georg Thieme Verlag KG Stuttgart · New York.

Draft-camp predictors of subsequent career success in the Australian Football League.

PubMed

Burgess, Darren; Naughton, Geraldine; Hopkins, Will

2012-11-01

The National Draft Camp results are generally considered to be important for informing talent scouts about the physical performance capacities of talented young Australian Rules Football (AFL) players. The purpose of this project was to determine magnitude of associations between five year career success in the AFL and physical draft camp tests, final draft selection order and previous match physical performance. Physical testing data of 99 players from the National Under 18 (U 18) competition were retrospectively analysed across 2002 and 2003 National Draft Camps. Physical match data was collected on these players and links with subsequent early career success (AFL games played) were explored. TrakPerformance Software was used to quantify the movement of 92 players during competitive games of the National U 18 Championships. Linear modelling using results from draft camp data involving 95 U 18 players, along with final draft selection order, was used to predict five year career success in senior AFL. Multiple U 18 match variables demonstrated large associations (sprints/min=43% more games, % sprint=43% more games) with five year career success in AFL. Final draft order and single variable predictors had moderate associations with career success. Neither U 18 matches nor draft camp testing was predictive of injuries incurring over the five years. Variability in senior AFL career success had a large association with a combination of match physical variables and draft test results. The objective data available should be considered in the selection of prospective player success. Copyright © 2012 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Movement Pattern and Parameter Learning in Children: Effects of Feedback Frequency

ERIC Educational Resources Information Center

Goh, Hui-Ting; Kantak, Shailesh S.; Sullivan, Katherine J.

2012-01-01

Reduced feedback during practice has been shown to be detrimental to movement accuracy in children but not in young adults. We hypothesized that the reduced accuracy is attributable to reduced movement parameter learning, but not pattern learning, in children. A rapid arm movement task that required the acquisition of a motor pattern scaled to…

Conducting Expressively: Navigating Seven Misconceptions That Inhibit Meaningful Connection to Ensemble and Sound

ERIC Educational Resources Information Center

Snyder, Courtney

2016-01-01

When expressivity (ignited by imagination) is incorporated into the learning process for both the conductor (teacher) and player (student), the qualities of movement, communication, instruction, and ensemble sound all change for the better, often with less work. Expressive conducting allows the conductor to feel more connected to the music and the…

Integration of Active Video Games in Extracurricular Activity at Schools

ERIC Educational Resources Information Center

Lee, Jung Eun; Huang, Charles; Pope, Zachary; Gao, Zan

2015-01-01

Active video games require players to be physically active. Dance Dance Revolution (DDR) is an interactive dancing game that requires fast-foot movement coordinated with energetic music and visuals. The Wii and Xbox Kinect games have also become good active video games for the promotion of physical activity participation. These games are much more…

Are professional handball players at risk for developing a glenohumeral internal rotation deficit in their dominant arm?

PubMed

Seabra, Pedro; Van Eck, Carola F; Sá, Márcia; Torres, João

2017-05-01

Overhead athletes, such as baseball players, have been shown to have adaptive changes in the shoulder range of motion (ROM) of their dominant arm. Professional handball players are a unique subtype of overhead athletes with very different demands from baseball players. The aim of this study was to determine if professional handball players demonstrate differences in shoulder ROM between their dominant and non-dominant arm and try to relate them with new variables. Fifty professional male handball players were included and completed a questionnaire regarding age at which they started to play, number of hours they practice a week, field position and arm dominance. ROM measurements were performed including forward flexion (FF), external rotation with the shoulder in abduction (ABER) and with adducted arm (ADER) and internal rotation with shoulder in abduction (IR). Statistical analysis was performed to determine differences in ROM between the dominant and non-dominant shoulder and if there is a relationship between these differences and shoulder load or field position. The dominant arm showed decreased internal rotation (47 vs. 56 degrees, p < 0.001) and increased external rotation both with the arm abducted (99 vs. 88 degrees, p < 0.001) and at the side (62 vs 57 degrees, p = 0.001). This was not correlated with shoulder load for any movement (FF, p = 0.980; ABER, p = 0.741; ADER, p = 0.803; IR, p = 0.085) but was dependent on field position with first line players showing the highest internal rotation deficit (13 degrees vs. 6-7 degrees in the other field positions, p = 0.013). This study showed that professional male handball players with a first line position have a significant risk for developing a glenohumeral internal rotation deficit, similar to the phenomenon seen in baseball pitchers.

The World (of Warcraft) through the eyes of an expert.

PubMed

Marzouki, Yousri; Dusaucy, Valériane; Chanceaux, Myriam; Mathôt, Sebastiaan

2017-01-01

Negative correlations between pupil size and the tendency to look at salient locations were found in recent studies (e.g., Mathôt et al., 2015). It is hypothesized that this negative correlation might be explained by the mental effort put by participants in the task that leads in return to pupil dilation. Here we present an exploratory study on the effect of expertise on eye-movement behavior. Because there is no available standard tool to evaluate WoW players' expertise, we built an off-game questionnaire testing players' knowledge about WoW and acquired skills through completed raids, highest rated battlegrounds, Skill Points, etc. Experts ( N  = 4) and novices ( N  = 4) in the massively multiplayer online role-playing game World of Warcraft (WoW) viewed 24 designed video segments from the game that differ in regards with their content (i.e, informative locations) and visual complexity (i.e, salient locations). Consistent with previous studies, we found a negative correlation between pupil size and the tendency to look at salient locations (experts, r  =  - .17, p  < .0001, and novices, r  =  - .09, p  < .0001). This correlation has been interpreted in terms of mental effort: People are inherently biased to look at salient locations (sharp corners, bright lights, etc.), but are able (i.e., experts) to overcome this bias if they invest sufficient mental effort. Crucially, we observed that this correlation was stronger for expert WoW players than novice players ( Z  =  - 3.3, p  = .0011). This suggests that experts learned to improve control over eye-movement behavior by guiding their eyes towards informative, but potentially low-salient areas of the screen. These findings may contribute to our understanding of what makes an expert an expert.

Improving fitness of elite handball players: small-sided games vs. high-intensity intermittent training.

PubMed

Iacono, Antonio Dello; Eliakim, Alon; Meckel, Yoav

2015-03-01

The present study was designed to compare the effects of high-intensity intermittent training (HIIT) and small-sided games (SSGs) training on fitness variables of elite handball players. Eighteen highly trained players (mean age ± SD: 25.6 ± 0.5 years) were assigned to either HIIT or SSGs group training protocols twice per week for 8 weeks. The HIIT consisted of 12-24 × 15 seconds of high-intensity runs interspersed by 15 seconds of recovery. The SSGs training consisted of 3 against 3 small-sided handball games. Both training methods were matched for exercise duration and recovery at each training session. Before and after 8-week training, the following fitness variables were assessed-speed: 10- and 20-m sprint time, agility: handball agility specific test (HAST), upper arm strength: 1 repetition maximum (1RM) bench press test, lower limb power: counter-movement jump tests with (CMJarm) and without (CMJ) arm movement, and aerobic fitness (yo-yo intermittent recovery test level 1 [YYIRTL1]). Significant improvement was found in the YYIRTL1 (23.3 and 26.3%, respectively), 10-m sprint (2.3 and 4.1%, respectively) and 20-m sprint (2.1 and 4%, respectively), HAST (1.1 and 2.2%, respectively), 1RM bench press (6.8 and 12.3%, respectively), CMJ (7.4 and 10.8%, respectively), and CMJarm (6.4 and 8.9%, respectively) following training in both groups (p ≤ 0.05 for all). There was a significantly greater improvement in 10- and 20-m sprint, HAST, 1RM, CMJ, and CMJarm following the SSGs training compared with the HIIT (p ≤ 0.05 for all). These results indicated that both HIIT and SSGs are effective training methods for fitness development among elite adult handball players. However, SSGs training may be considered as the preferred training regimen for improving handball-specific fitness variables during the in-season period.

Physical Demands of Representative Match-Play in Adolescent Rugby Union.

PubMed

Read, Dale B; Jones, Ben; Phibbs, Padraic J; Roe, Gregory A B; Darrall-Jones, Joshua D; Weakley, Jonathon J S; Till, Kevin

2017-05-01

Read, DB, Jones, B, Phibbs, PJ, Roe, GAB, Darrall-Jones, J, Weakley, JJS, and Till, K. Physical demands of representative match-play in adolescent rugby union. J Strength Cond Res 31(5): 1290-1296, 2017-The purpose of this study was to quantify the physical demands of representative adolescent rugby union match-play and investigate the difference between playing positions and age groups. Players (n = 112) were classified into 6 groups by playing position (forwards and backs) and age group (U16, U18, and U20). The physical demands were measured using microsensor-based technology and analyzed using magnitude-based inferences to assess practical importance. Backs had a greater relative distance (except U16s) and a greater high-speed running distance per minute than forwards, with the magnitude of difference between the positions becoming larger in older age groups. Forwards had higher values of PlayerLoad (PL) per minute (accumulated accelerations from the 3 axes of movement) and PL slow per minute (accumulated accelerations from the 3 axes of movement where velocity is <2 m·s) than backs at all age groups. Relative distance, low-, and high-speed running per minute all had a trend to be lower in older age groups for both positions. PlayerLoad per minute was greater in U18 than that in U16 and U20 for both positions. PlayerLoad slow per minute was greater for older age groups besides the U18 and U20 comparisons, which were unclear. The contrasts in physical demands experienced by different positions reinforce the need for greater exposure to sprinting and collision-based activity for backs and forwards, respectively. Given PL metrics peak at U18 and locomotor demands seem to be lower in older ages, the demands of representative adolescent rugby union do not seem to be greater at U20 as expected.

Dissecting the links between cerebellum and dystonia.

PubMed

Malone, Ailish; Manto, Mario; Hass, Chris

2014-12-01

Dystonia is a common movement disorder characterized by sustained muscle contractions. These contractions generate twisting and repetitive movements or typical abnormal postures, often exacerbated by voluntary movement. Dystonia can affect almost all the voluntary muscles. For several decades, the discussion on the pathogenesis has been focused on basal ganglia circuits, especially striatal networks. So far, although dystonia has been observed in some forms of ataxia such as dominant ataxias, the link between the cerebellum and dystonia has remained unclear. Recent human studies and experimental data mainly in rodents show that the cerebellum circuitry could also be a key player in the pathogenesis of some forms of dystonia. In particular, studies based on behavioral adaptation paradigm shed light on the links between dystonia and cerebellum. The spectrum of movement disorders in which the cerebellum is implicated is continuously expanding, and manipulation of cerebellar circuits might even emerge as a candidate therapy in the coming years.

Movement patterns of limb coordination in infant rolling.

PubMed

Kobayashi, Yoshio; Watanabe, Hama; Taga, Gentaro

2016-12-01

Infants must perform dynamic whole-body movements to initiate rolling, a key motor skill. However, little is known regarding limb coordination and postural control in infant rolling. To address this lack of knowledge, we examined movement patterns and limb coordination during rolling in younger infants (aged 5-7 months) that had just begun to roll and in older infants (aged 8-10 months) with greater rolling experience. Due to anticipated difficulty in obtaining measurements over the second half of the rolling sequence, we limited our analysis to the first half. Ipsilateral and contralateral limbs were identified on the basis of rolling direction and were classified as either a stationary limb used for postural stability or a moving limb used for controlled movement. We classified the observed movement patterns by identifying the number of stationary limbs and the serial order of combinational limb movement patterns. Notably, older infants performed more movement patterns that involved a lower number of stationary limbs than younger infants. Despite the wide range of possible movement patterns, a small group of basic patterns dominated in both age groups. Our results suggest that the fundamental structure of limb coordination during rolling in the early acquisition stages remains unchanged until at least 8-10 months of age. However, compared to younger infants, older infants exhibited a greater ability to select an effective rotational movement by positioning themselves with fewer stationary limbs and performing faster limb movements.

Exploring children's movement characteristics during virtual reality video game play.

PubMed

Levac, Danielle; Pierrynowski, Michael R; Canestraro, Melissa; Gurr, Lindsay; Leonard, Laurean; Neeley, Christyann

2010-12-01

There is increasing interest in the use of commercially-available virtual reality video gaming systems within pediatric rehabilitation, yet little is known about the movement characteristics of game play. This study describes quantity and quality of movement during Nintendo Wii and Wii Fit game play, explores differences in these movement characteristics between games and between novice and experienced players, and investigates whether motivation to succeed at the game impacts movement characteristics. Thirty-eight children (aged 7-12) with and without previous game experience played Wii (boxing and tennis) and Wii Fit (ski slalom and soccer heading) games. Force plate data provided center of pressure displacement (quantity) and processed pelvis motion indicated smoothness of pelvic movement (quality). Children rated their motivation to succeed at each game. Movement quantity and quality differed between games (p<.001). Children with previous experience playing Wii Fit games demonstrated greater movement quantity during Wii Fit game play (p<.001); quality of movement did not differ between groups. Motivation to succeed did not influence the relationship between experience and outcomes. Findings enhance clinical understanding of this technology and inform the development of research questions to explore its potential to improve movement skills in children with motor impairments. Copyright © 2010 Elsevier B.V. All rights reserved.

The effects of time pressure on chess skill: an investigation into fast and slow processes underlying expert performance.

PubMed

van Harreveld, Frenk; Wagenmakers, Eric-Jan; van der Maas, Han L J

2007-09-01

The ability to play chess is generally assumed to depend on two types of processes: slow processes such as search, and fast processes such as pattern recognition. It has been argued that an increase in time pressure during a game selectively hinders the ability to engage in slow processes. Here we study the effect of time pressure on expert chess performance in order to test the hypothesis that compared to weak players, strong players depend relatively heavily on fast processes. In the first study we examine the performance of players of various strengths at an online chess server, for games played under different time controls. In a second study we examine the effect of time controls on performance in world championship matches. Both studies consistently show that skill differences between players become less predictive of the game outcome as the time controls are tightened. This result indicates that slow processes are at least as important for strong players as they are for weak players. Our findings pose a challenge for current theorizing in the field of expertise and chess.

Abnormal motor patterns in the framework of the equilibrium-point hypothesis: a cause for dystonic movements?

PubMed

Latash, M L; Gutman, S R

1994-01-01

Until now, the equilibrium-point hypothesis (lambda model) of motor control has assumed nonintersecting force-length characteristics of the tonic stretch reflex for individual muscles. Limited data from animal experiments suggest, however, that such intersections may occur. We have assumed the possibility of intersection of the characteristics of the tonic stretch reflex and performed a computer simulation of movement trajectories and electromyographic patterns. The simulation has demonstrated, in particular, that a transient change in the slope of the characteristic of an agonist muscle may lead to temporary movement reversals, hesitations, oscillations, and multiple electromyographic bursts that are typical of movements of patients with dystonia. The movement patterns of three patients with idiopathic dystonia during attempts at fast single-joint movements (in the elbow, wrist, and ankle) were recorded and compared with the results of the computer simulation. This approach considers that motor disorders in dystonia result from faulty control patterns that may not correlate with any morphological or neurophysiological changes. It provides a basis for the high variability of dystonic movements. The uniqueness of abnormal motor patterns in dystonia, that precludes statistical analysis across patients, may result from subtle differences in the patterns of intersecting characteristics of the tonic stretch reflex. The applicability of our analysis to disordered multijoint movement patterns is discussed.

Alterations in echocardiographic and electrocardiographic features in Japanese professional soccer players: comparison to African-Caucasian ethnicities.

PubMed

Kervio, Gaëlle; Pelliccia, Antonio; Nagashima, Junzo; Wilson, Mathew G; Gauthier, Jean; Murayama, Masahiro; Uzan, Laurent; Ville, Nathalie; Carré, François

2013-10-01

Scarce data are available regarding the electrocardiographic (ECG) and echocardiographic changes in athletes of Asian origin. We investigate the ECG and echocardiographic patterns in Japanese (J) compared with African-Caribbean (AC) and Caucasian (C) athletes. A total of 282 professional soccer players (68 J, 96 AC and 118 C) matched for age, gender, sport and level of achievement was examined. ECGs were without alterations in 62% of J (versus 69% of C, p = non significant and 44% of AC, p < 0.001). The most common alterations in J were sinus bradycardia (69%), incomplete right bundle branch block (RBBB; 43%), early repolarization (18%), isolated increase in R/S-wave (10%), Q-waves (9%). Remarkably, no J athlete showed deeply T-wave inversion, in contrast to 6% of AC (p < 0.05). Occasionally, J showed J-point upward/domed ST-elevation with inverted/biphasic T-wave (6% versus 16.5% in AC, p < 0.01). J demonstrated larger left ventricular (LV) cavity compared with AC and C players (55.2 ± 3.3 versus 52.2 ± 3.8 and 53.9 ± 3.7 mm, respectively, p < 0.01), with an important subset ( > 4%) presenting a markedly enlarged cavity (>60 mm), in the presence of normal systolic/diastolic function and no segmental abnormalities. Therefore, J showed a more eccentric remodelling compared with AC and C (relative wall thickness: 0.31 ± 0.05, 0.38 ± 0.06 and 0.36 ± 0.06, respectively, p < 0.01). J players show the most eccentric LV remodelling compared with C and AC players. In association, certain training-related ECG patterns, i.e. sinus bradycardia and isolated increase in R/S-wave voltage, are present in a larger proportion of J players than previously described in C players. Conversely, no J athlete showed deeply T-wave inversion, as commonly found in AC and occasionally in C.

Fluctuations in Activity Demands Across Game Quarters in Professional and Semiprofessional Male Basketball.

PubMed

Scanlan, Aaron T; Tucker, Patrick S; Dascombe, Ben J; Berkelmans, Daniel M; Hiskens, Matthew I; Dalbo, Vincent J

2015-11-01

Examination of activity demands and stoppage durations across game periods provides useful insight concerning fatigue, tactical strategies, and playing pace in team sports such as basketball. Therefore, the aims of this study were to quantify and compare game activity fluctuations across quarters in professional and semiprofessional basketball players. Video-based time-motion analyses were conducted across multiple games. Frequencies, total durations (in seconds), total distances (in meters), and mean velocities (in meters per second) were calculated for low-intensity movement (≤3 m·s), high-intensity movement (>3 m·s), shuffling, and dribbling activity. Frequencies were determined for jumping and upper-body activity; stoppage durations were also calculated. Separate repeated-measures analysis of variance and Cohen's d were used to identify significant differences and quantify the effect sizes between game quarters for all outcome measures, respectively. Pearson correlation analyses were performed to determine the relationship between stoppage duration and all activity measures. The results showed significantly (p ≤ 0.05) reduced dribbling (3.09 ± 0.03 m·s vs. 2.81 ± 0.01 m·s) and total (2.22 ± 0.04 m·s vs. 2.09 ± 0.03 m·s) activity velocities during the third compared with the first quarter in professional players. Furthermore, effect size analyses showed greater decreases in high-intensity (professional: d = 1.7-5.4; semiprofessional: d = 0.3-1.7), shuffling (professional: d = 2.3-3.2; semiprofessional: d = 1.4-2.1), and total (professional: d = 1.0-4.9; semiprofessional: d = 0.3-0.8) activity and increases in dribbling (professional: d = 1.4-4.7; semiprofessional: d = 2.5-2.8) with game progression in professional players. In semiprofessional players, stoppage duration was significantly (p ≤ 0.05) related to various low-intensity (R = 0.64-0.72), high-intensity (R = 0.65-0.72), and total (R = 0.63-0.73) activity measures. Although not directly measured, the observed game activity fluctuations were likely because of a combination of physiological (e.g., muscle glycogen depletion, dehydration), tactical (e.g., ball control, game pace), and game-related (e.g., time-outs, player fouls) factors. Basketball coaches can use the provided data to (a) develop more precise training plans and management strategies, (b) elevate semiprofessional player performance closer to the professional level, and (c) incorporate tactical strategies to maximize the benefits of stoppages.

Movement and Movement Patterns of Early Childhood.

ERIC Educational Resources Information Center

Sinclair, Caroline B.

This study was undertaken to determine the progressive development in movement and movement patterns (coordinated movements of body parts used involuntarily to achieve an objective) of children 2- to 6-years-old, to identify general characteristics which may be studied for appraisal of growth and development, and to study variations in movement…

Racquet sports--patterns of injury presenting to a sports injury clinic.

PubMed Central

Chard, M D; Lachmann, S M

1987-01-01

In an 8-year retrospective study, 631 injuries due to the racquet sports of squash (59%), tennis (21%) and badminton (20%) were seen in a sports injury clinic, males predominating (58 to 66%). The proportion of squash injuries was higher than expected and probably relates to higher physical stress and risk of contact in this sport. Also they occurred mainly in persons over 25 years (59%) i.e. the reverse for sport in general. Acute traumatic injuries were seen especially in squash players, a majority affecting the knee, lumbar region, muscles and ankle. Tennis injuries differed most with lateral epicondylitis, patello-femoral pain and lumbar disc prolapse being relatively common. The badminton injury pattern overlapped the others. Lower limb injuries predominated in all three. Detailed assessment of 106 cases showed many to be new, infrequent, social players. Poor warm-up was a common factor in new and established players. The importance of these findings is discussed. PMID:3435816

A comparison of take-off dynamics during three different spikes, block and counter-movement jump in female volleyball players.

PubMed

Kabacinski, Jaroslae; Dworak, Lecholslaw B; Murawa, Michal; Ostarello, John; Rzepnicka, Agata; Maczynski, Jacek

2016-12-01

The purpose of the study was to compare the take-off dynamics in counter-movement jump (CMJ), volleyball block and spikes. Twelve professional female players, representing the highest volleyball league in Poland, participated in the laboratory tests. A force platform was used to record ground reaction force (GRF) during take-off phase in CMJ test, block from a run-up and spikes: front row attack, slide attack, back row attack. Vertical (v) GRF (peak: Rmax and integral mean: ), impulse of vGRF (J) and mechanical power (peak: Pmax and integral mean:

) were analyzed. Significant differences (P<0.05) of values of the dynamic parameters (Rmax, , J, Pmax, and

) were found between CMJ, block from a run-up and three different technique spikes. The highest values were recorded during take-off in the back row attack: peak vGRF (2.93±0.05 BW), integral mean vGRF (1.90±0.08 BW), impulse of vGRF (354±40 Ns), peak power (5320±918 W) and integral mean power (3604±683 W). Peak power (2608±217 W) and integral mean power (1417±94 W) were determined in CMJ test to evaluate the force-velocity capabilities of the players. In terms of GRF and the mechanical power, high level of dynamics in take-off influences positively the jumping height and significantly increases the effectiveness of attacks during spike of the ball over the block of the opponent.

A prospective cohort study identifying risk factors for shoulder injuries in adolescent elite handball players: the Karolinska Handball Study (KHAST) study protocol.

PubMed

Asker, Martin; Waldén, Markus; Källberg, Henrik; Holm, Lena W; Skillgate, Eva

2017-11-22

Handball is a physical contact sport that includes frequent overhead throwing, and this combination leads to a high rate of shoulder injuries. Several factors have been associated with shoulder injuries in overhead athletes, but strong scientific evidence is lacking for most suggested risk factors. We therefore designed the Karolinska Handball Study (KHAST) with the aim to identify risk factors for shoulder injuries in adolescent male and female elite handball players studying at handball-profiled secondary schools in Sweden. Secondary objectives are to investigate whether shoulder function changes during the competition season and whether the physical profile of the players changes during their time in secondary school. Players aged 15 to 19 years were included during the pre-season period of the 2014-2015 and the 2015-2016 seasons. At inclusion, players signed informed consent and filled in a questionnaire regarding playing position, playing level, previous handball experience, history of shoulder problems and athletic identity. Players also completed a detailed test battery at baseline evaluating the shoulder, neck and trunk. Players were then prospectively monitored weekly during the 2014-2015 and/or 2015-2016 competitive seasons regarding injuries and training/match workload. Results from the annual routine physical tests in the secondary school curriculum including bench press, deep squat, hand grip strength, clean lifts, squat jumps, counter movement jumps, <30 m sprints, chins, dips and Cooper's test will be collected until the end of the competitive season 2017-2018. The primary outcome is the incidence of shoulder injuries and shoulder problems. The secondary outcome is the prevalence of shoulder injuries and shoulder problems. Shoulder problems are frequent among handball players and a reduction of these injuries is therefore warranted. However, in order to introduce appropriate preventive measures, a detailed understanding of the underlying risk factors is needed. Our study has a high potential to identify important risk factors for shoulder injuries in adolescent elite handball players owing to a large study sample, a high response rate, data collection during consecutive seasons, and recording of potential confounding factors.

Fine motor skills in adult Tourette patients are task-dependent.

PubMed

Neuner, Irene; Arrubla, Jorge; Ehlen, Corinna; Janouschek, Hildegard; Nordt, Carlos; Fimm, Bruno; Schneider, Frank; Shah, N Jon; Kawohl, Wolfram

2012-10-11

Tourette syndrome is a neuropsychiatric disorder characterized by motor and phonic tics. Deficient motor inhibition underlying tics is one of the main hypotheses in its pathophysiology. Therefore the question arises whether this supposed deficient motor inhibition affects also voluntary movements. Despite severe motor tics, different personalities who suffer from Tourette perform successfully as neurosurgeon, pilot or professional basketball player. For the investigation of fine motor skills we conducted a motor performance test battery in an adult Tourette sample and an age matched group of healthy controls. The Tourette patients showed a significant lower performance in the categories steadiness of both hands and aiming of the right hand in comparison to the healthy controls. A comparison of patients' subgroup without comorbidities or medication and healthy controls revealed a significant difference in the category steadiness of the right hand. Our results show that steadiness and visuomotor integration of fine motor skills are altered in our adult sample but not precision and speed of movements. This alteration pattern might be the clinical vignette of complex adaptations in the excitability of the motor system on the basis of altered cortical and subcortical components. The structurally and functionally altered neuronal components could encompass orbitofrontal, ventrolateral prefrontal and parietal cortices, the anterior cingulate, amygdala, primary motor and sensorimotor areas including altered corticospinal projections, the corpus callosum and the basal ganglia.

The Effect of a Novel Movement Strategy in Decreasing ACL Risk Factors in Female Adolescent Soccer Players: A Randomized Controlled Trial

PubMed Central

Celebrini, Richard G.; Eng, Janice J.; Miller, William C.; Ekegren, Christina L.; Johnston, James D.; Depew, Thomas A.; MacIntyre, Donna L.

2015-01-01

Objective To determine the effect of a novel movement strategy incorporated within a soccer warm-up on biomechanical risk factors for ACL injury during three sport-specific movement tasks. Design Single-blind, randomized controlled clinical trial. Setting Laboratory setting. Participants 20 top-tier female teenage soccer players. Interventions Subjects were randomized to the Core Position and Control movement strategy (Core-PAC) warm-up or standard warm-up which took place prior to their regular soccer practice over a 6-week period. The Core-PAC focuses on getting the centre of mass closer to the plant foot or base of support. Main Outcome Measures Peak knee flexion angle and abduction moments during a side-hop (SH), side-cut (SC) and unanticipated side-cut (USC) task after the 6-weeks with (intervention group only) and without a reminder to use the Core-PAC strategy. Results The Core-PAC group increased peak flexion angles during the SH task (Mean difference = 6.2°, 95% CI: 1.9–10.5°, effect size = 1.01, P = 0.034) after the 6-week warm-up program without a reminder. In addition, the Core-PAC group demonstrated increased knee flexion angles for the side-cut (Mean difference = 8.5°, 95% CI: 4.8–12.2°, ES = 2.02, P = 0.001) and side-hop (Mean difference = 10.0°, 95% CI: 5.7–14.3°, ES = 1.66, P = 0.001) task after a reminder. No changes in abduction moments were found. Conclusions The results of this study suggest that the Core-PAC may be one method of modifying high-risk soccer-specific movements and can be implemented within a practical, team-based soccer warm-up. The results should be interpreted with caution due to the small sample size. PMID:24184850

Tennis players show a lower coactivation of the elbow antagonist muscles during isokinetic exercises.

PubMed

Bazzucchi, Ilenia; Riccio, Maria Elena; Felici, Francesco

2008-10-01

Previous studies have suggested that muscle coactivation could be reduced by a recurrent activity (training, daily activities). If this was correct, skilled athletes should show a specific muscle activation pattern with a low level of coactivation of muscles which are typically involved in their discipline. In particular, the aim of this study was to verify the hypothesis that the amount of antagonist activation of biceps brachii (BB) and triceps brachii (TB) is different between tennis players and non-players individuals during maximal isokinetic contractions. Ten young healthy men and eight male tennis players participated in the study. The surface electromyographic signals (sEMG) were recorded from the BB and TB muscles during three maximal voluntary isometric contractions (MVC) of elbow flexors and extensors and a set of three maximal elbow flexions and extensions at 15 degrees , 30 degrees , 60 degrees , 120 degrees , 180 degrees and 240 degrees /s. Normalized root mean square (RMS) of sEMG was calculated as an index of sEMG amplitude. Antagonist activation (%RMSmax) of TB was significantly lower in tennis players (from 14.0+/-7.9% at MVC to 16.3+/-8.9% at 240 degrees /s) with respect to non-players (from 27.7+/-19.7% at MVC to 38.7+/-17.6% at 240 degrees /s) at all angular velocities. Contrary to non-players, tennis players did not show any difference in antagonist activation between BB and TB muscles. Tennis players, with a constant practice in controlling forces around the elbow joint, learn how to reduce coactivation of muscles involved in the control of this joint. This has been shown by the lower antagonist muscular activity of triceps brachii muscle during isokinetic elbow flexion found in tennis players with respect to non-players.

Preparation time influences ankle and knee joint control during dynamic change of direction movements.

PubMed

Fuerst, Patrick; Gollhofer, Albert; Gehring, Dominic

2017-04-01

The influence of preparation time on ankle joint biomechanics during highly dynamic movements is largely unknown. The aim of this study was to evaluate the impact of limited preparation time on ankle joint loading during highly dynamic run-and-cut movements. Thirteen male basketball players performed 45°-sidestep-cutting and 180°-turning manoeuvres in reaction to light signals which appeared during the approach run. Both movements were executed under (1) an easy condition, in which the light signal appeared very early, (2) a medium condition and (3) a hard condition with very little time to prepare the movements. Maximum ankle inversion angles, moments and velocities during ground contact, as well as EMG signals of three lower extremity muscles, were analysed. In 180°-turning movements, reduced preparation time led to significantly increased maximum ankle inversion velocities. Muscular activation levels, however, did not change. Increased inversion velocities, without accompanying changes in muscular activation, may have the potential to destabilise the ankle joint when less preparation time is available. This may result in a higher injury risk during turning movements and should therefore be considered in ankle injury research and the aetiology of ankle sprains.

The Evolving Treatment Patterns of NCAA Division I Football Players by Orthopaedic Team Physicians Over the Past Decade, 2008-2016.

PubMed

Carver, Trevor J; Schrock, John B; Kraeutler, Matthew J; McCarty, Eric C

Previous studies have analyzed the treatment patterns used to manage injuries in National Collegiate Athletic Association (NCAA) Division I football players. Treatment patterns used to manage injuries in NCAA Division I football players will have changed over the study period. Descriptive epidemiology study. Level 5. The head orthopaedic team physicians for all 128 NCAA Division I football teams were asked to complete a survey containing questions regarding experience as team physician, medical coverage of the team, reimbursement issues, and treatment preferences for some of the most common injuries occurring in football players. Responses from the current survey were compared with responses from the same survey sent to NCAA Division I team physicians in 2008. Responses were received from 111 (111/119, 93%) NCAA Division I orthopaedic team physicians in 2008 and 115 (115/128, 90%) orthopaedic team physicians between April 2016 and April 2017. The proportion of team physicians who prefer a patellar tendon autograft for primary anterior cruciate ligament reconstruction (ACLR) increased from 67% in 2008 to 83% in 2016 ( P < 0.001). The proportion of team physicians who perform anterior shoulder stabilization arthroscopically increased from 69% in 2008 to 93% in 2016 ( P < 0.0001). Of team physicians who perform surgery for grade III posterior cruciate ligament (PCL) injuries, the proportion who use the arthroscopic single-bundle technique increased from 49% in 2008 to 83% in 2016 ( P < 0.0001). The proportion of team physicians who use Toradol injections prior to a game to help with nagging injuries decreased from 62% in 2008 to 26% in 2016 ( P < 0.0001). Orthopaedic physicians changed their injury treatment preferences for NCAA Division I football players over the study period. In particular, physicians have changed their preferred techniques for ACLR, anterior shoulder stabilization, and PCL reconstruction. Physicians have also become more conservative with pregame Toradol injections. These opinions may help guide treatment decisions and lead to better care of all athletes.

Tactile Cueing for Target Acquisition and Identification

DTIC Science & Technology

2005-09-01

method of coding tactile information, and the method of presenting elevation information were studied. Results: Subjects were divided into video game experienced...VGP) subjects and non- video game (NVGP) experienced subjects. VGPs showed a significantly lower’ target acquisition time with the 12...that video game players performed better with the highest level of tactile resolution, while non- video game players performed better with simpler pattern and a lower resolution display.

Players Off the Field. How Jim Delany and Roy Kramer Took over Big-Time College Sports.

ERIC Educational Resources Information Center

Suggs, Welch

2000-01-01

Traces the history of the college football bowl system and describes the movement toward replacing the bowl game system with a national championship playoff system. Focuses on the roles of J. Delany, commission of the Big Ten Conference and R. Kramer, commissioner of the Southeastern Conference, in perpetuating the current college football bowl…

Top-Level Players' Visual Control of Interceptive Actions: Bootsma and Van Wieringen (1990) 20 Years Later

ERIC Educational Resources Information Center

Bootsma, Reinoud J.; Fernandez, Laure; Morice, Antoine H. P.; Montagne, Gilles

2010-01-01

Using a two-step approach, Van Soest et al. (2010) recently questioned the pertinence of the conclusions drawn by Bootsma and Van Wieringen (1990) with respect to the visual regulation of an exemplary rapid interceptive action: the attacking forehand drive in table tennis. In the first step, they experimentally compared the movement behaviors of…

U.S. Indian Policy, 1865-1890: As Illuminated through the Lives of Charles A. Eastman and Elaine Goodale Eastman

ERIC Educational Resources Information Center

Eick, Gretchen Cassel

2008-01-01

This article lays out U.S. Indian policy in the Great Plains during the twenty-five years after the Civil War by examining chronologically specific "players" that shaped and reshaped that policy: the U.S. Army, the President and Interior Department, Congress, religious organizations, whites in the Indian reform movement, settlers surging…

The relationship between movement speed and duration during soccer matches.

PubMed

Roecker, Kai; Mahler, Hubert; Heyde, Christian; Röll, Mareike; Gollhofer, Albert

2017-01-01

The relationship between the time duration of movement (t(dur)) and related maximum possible power output has been studied and modeled under many conditions. Inspired by the so-called power profiles known for discontinuous endurance sports like cycling, and the critical power concept of Monod and Scherrer, the aim of this study was to evaluate the numerical characteristics of the function between maximum horizontal movement velocity (HSpeed) and t(dur) in soccer. To evaluate this relationship, GPS data from 38 healthy soccer players and 82 game participations (≥30 min active playtime) were used to select maximum HSpeed for 21 distinct t(dur) values (between 0.3 s and 2,700 s) based on moving medians with an incremental t(dur) window-size. As a result, the relationship between HSpeed and Log(t(dur)) appeared reproducibly as a sigmoidal decay function, and could be fitted to a five-parameter equation with upper and lower asymptotes, and an inflection point, power and decrease rate. Thus, the first three parameters described individual characteristics if evaluated using mixed-model analysis. This study shows for the first time the general numerical relationship between t(dur) and HSpeed in soccer games. In contrast to former descriptions that have evaluated speed against power, HSpeed against t(dur) always yields a sigmoidal shape with a new upper asymptote. The evaluated curve fit potentially describes the maximum moving speed of individual players during the game, and allows for concise interpretations of the functional state of team sports athletes.

The relationship between movement speed and duration during soccer matches

PubMed Central

Mahler, Hubert; Heyde, Christian; Röll, Mareike; Gollhofer, Albert

2017-01-01

The relationship between the time duration of movement (t(dur)) and related maximum possible power output has been studied and modeled under many conditions. Inspired by the so-called power profiles known for discontinuous endurance sports like cycling, and the critical power concept of Monod and Scherrer, the aim of this study was to evaluate the numerical characteristics of the function between maximum horizontal movement velocity (HSpeed) and t(dur) in soccer. To evaluate this relationship, GPS data from 38 healthy soccer players and 82 game participations (≥30 min active playtime) were used to select maximum HSpeed for 21 distinct t(dur) values (between 0.3 s and 2,700 s) based on moving medians with an incremental t(dur) window-size. As a result, the relationship between HSpeed and Log(t(dur)) appeared reproducibly as a sigmoidal decay function, and could be fitted to a five-parameter equation with upper and lower asymptotes, and an inflection point, power and decrease rate. Thus, the first three parameters described individual characteristics if evaluated using mixed-model analysis. This study shows for the first time the general numerical relationship between t(dur) and HSpeed in soccer games. In contrast to former descriptions that have evaluated speed against power, HSpeed against t(dur) always yields a sigmoidal shape with a new upper asymptote. The evaluated curve fit potentially describes the maximum moving speed of individual players during the game, and allows for concise interpretations of the functional state of team sports athletes. PMID:28742832

Effect of a gluteal activation warm-up on explosive exercise performance.

PubMed

Parr, Matt; Price, Phil Db; Cleather, Daniel J

2017-01-01

To evaluate the effect of a gluteal activation warm-up on the performance of an explosive exercise (the high hang pull (HHP)). Seventeen professional rugby union players performed one set of three HHPs (with 80% of their one repetition maximum load) following both a control and activation warm-up. Peak electrical activity of the gluteus maximus and medius was quantified using electromyography (EMG). In addition, the kinematics and kinetics of nine players was also recorded using force plate and motion capture technology. These data were analysed using a previously described musculoskeletal model of the right lower limb in order to provide estimates of the muscular force expressed during the movement. The mean peak EMG activity of the gluteus maximus was significantly lower following the activation warm-up as compared with the control (p<0.05, effect size d=0.30). There were no significant differences in the mean peak estimated forces in gluteus maximus and medius, the quadriceps or hamstrings (p=0.053), although there was a trend towards increased force in gluteus maximus and hamstrings following the activation warm-up. There were no differences between the ground reaction forces following the two warm-ups. This study suggests that a gluteal activation warm-up may facilitate recruitment of the gluteal musculature by potentiating the glutes in such a way that a smaller neural drive evokes the same or greater force production during movement. This could in turn potentially improve movement quality.

Longitudinal Study of Repeated Sprint Performance in Youth Soccer Players of Contrasting Skeletal Maturity Status

PubMed Central

Valente-dos-Santos, João; Coelho-e-Silva, Manuel J.; Severino, Vítor; Duarte, João; Martins, Raúl S.; Figueiredo, António J.; Seabra, André T.; Philippaerts, Renaat M.; Cumming, Sean P; Elferink-Gemser, Marije; Malina, Robert M.

2012-01-01

The purpose of the study was to evaluate the developmental changes in performance in a repeated-sprint ability (RSA) test in young soccer players of contrasting maturity status. A total of 83 regional level Portuguese youth soccer players, aged 11-13 years at baseline was assessed annually. Stature, body mass, 7x34.2-m sprint protocol (25-s active recovery), 20-m multi-stage continuous shuttle endurance run and counter-movement jump (CMJ) without the use of the arms were measured. Fat-free mass (FFM) was determined by age and gender-specific formulas. Developmental changes in total sprint time across ages were predicted using multilevel modeling. Corresponding measurements were performed on an independent cross-sectional subsample of 52 youth soccer players 11-17 years to evaluate the predictive model. CA, CA2, maturational status (SA-CA), body size (mass and stature), FFM, aerobic endurance, lower limb explosive strength and annual volume training significantly improved the statistical fit of the RSA multilevel model. In ‘late’ maturing athletes, the best model for predicting change in RSA was expressed by the following equation: 86.54 - 2.87 x CA + 0.05 x CA2 - 0.25 x FFM + 0.15 x body mass + 0.05 x stature - 0.05 x aerobic endurance - 0.09 x lower limb explosive strength - 0.01 x annual volume training. The best fitting models for players who were ‘on time’ and ‘early’ maturing were identical to the best model for late maturing players, less 0.64 seconds and 1.74 seconds, respectively. Multilevel modeling provided performance curves that permitted the prediction of individual RSA performance across adolescent years in regional level soccer players. Key pointsRepeated-sprint ability tests are a valuable sport-specific field test of sprint performance in youth soccer players. Here, the test had reasonable reliability and can be useful to trainers and coaches in the assessment of young athletes and in monitoring changes over time.The total sprint time of youth soccer players advanced in biological maturation improves more, on average, than that of players who are on time (average) and late in maturation. The performance difference between early and late maturing players is consistent after about 13 years of age.Multilevel modeling is a promising statistical technique for analyzing the development of functional capacity in a sport. It has the potential to provide useful information to assist trainers and coaches in evaluating and facilitating the development of individual players. PMID:24149342

An evaluation of end-point trajectory planning during skilled kicking.

PubMed

Ford, Paul; Hodges, Nicola J; Mark Williams, A

2009-01-01

There is evidence that actions are planned by anticipation of their external effects, with the strength of this effect being dependent on the amount of prior practice. In Experiment 1, skilled soccer players performed a kicking task under four conditions: planning in terms of an external action effect (i.e., ball trajectory) or in terms of body movements, either with or without visual error feedback. When feedback was withheld, a ball focus resulted in more accurate outcomes than a body focus. When visual feedback was allowed, there was no difference between these two conditions. In Experiment 2, both skilled and novice soccer players were tested with the addition of a control condition and in the absence of visual feedback. For both groups there was evidence that a ball focus was more beneficial for performance than a body focus, particularly in terms of movement kinematics where correlations across the joints were generally higher for body rather than ball planning. Most skilled participants reported that ball planning felt more normal than body planning. These experiments provide some evidence that actions are planned in terms of their external action effects, supporting the common-coding hypothesis of action planning.

The price of racial bias: intergroup negotiations in the ultimatum game.

PubMed

Kubota, Jennifer T; Li, Jian; Bar-David, Eyal; Banaji, Mahzarin R; Phelps, Elizabeth A

2013-12-01

Existing stereotypes about Black Americans may influence perceptions of intent during financial negotiations. In this study, we explored whether the influence of race on economic decisions extends to choices that are costly to the decision maker. We investigated whether racial group membership contributes to differential likelihood of rejection of objectively equal unfair monetary offers. In the Ultimatum Game, players accept or reject proposed splits of money. Players keep accepted splits, but if a player rejects an offer, both the player and the proposer receive nothing. We found that participants accepted more offers and lower offer amounts from White proposers than from Black proposers, and that this pattern was accentuated for participants with higher implicit race bias. These findings indicate that participants are willing to discriminate against Black proposers even at a cost to their own financial gain.

The Price of Racial Bias: Intergroup Negotiations in the Ultimatum Game

PubMed Central

Kubota, Jennifer T.; Li, Jian; Bar-David, Eyal; Banaji, Mahzarin R.; Phelps, Elizabeth A.

2014-01-01

Existing stereotypes about Black Americans may influence perceptions of intent during financial negotiations. In this study, we explored whether the influence of race on economic decisions extends to choices that are costly to the decision maker. We investigated whether racial group membership contributes to differential likelihood of rejection of objectively equal unfair monetary offers. In the Ultimatum Game, players accept or reject proposed splits of money. Players keep accepted splits, but if a player rejects an offer, both the player and the proposer receive nothing. We found that participants accepted more offers and lower offer amounts from White proposers than from Black proposers, and that this pattern was accentuated for participants with higher implicit race bias. These findings indicate that participants are willing to discriminate against Black proposers even at a cost to their own financial gain. PMID:24121413

The locomotor activity of soccer players based on playing positions during the 2010 World Cup.

PubMed

Soroka, Andrzej

2018-06-01

The aim of this study was to define the locomotor activity of footballer players during the 2010 World Cup and to assess what differences existed among different playing positions. Research was conducted using research material collected from the Castrol Performance Index, a kinematic game analysis system that records player movements during a game by use of semi-automatic cameras. A total of 599 players who participated in the championships were analyzed. The results were evaluated using one-way analysis of variance (ANOVA) and a post-hoc test that calculated the Honestly Significant Difference (HSD) in order to determine which mean values significantly differed among the player positions. It was found that midfielders covered on average the largest distance during a match (10,777.6 m, P<0.001) as well as performing the most locomotor activity at high and sprint intensities (2936.8 m and 108.4 m, respectively). Additionally, midfielders also spent the largest amount of time at performing at a high intensity (10.6%). Strikers also featured high levels of the above parameters; the total length of distance covered with high intensities was found to be on average 2586.7 m, the distance covered at sprint intensity was 105 m. The footballers, playing at the championship level feature excellent locomotor preparation. This fact is undoubtedly supported by the aerobic training of high intensity. Such training allows footballers to extend the distance they cover during the match, increase the intensity of locomotor activities and sprint speed distance.

Posterior tibial slope as a risk factor for anterior cruciate ligament rupture in soccer players.

PubMed

Senişik, Seçkin; Ozgürbüz, Cengizhan; Ergün, Metin; Yüksel, Oğuz; Taskiran, Emin; Işlegen, Cetin; Ertat, Ahmet

2011-01-01

Anterior cruciate ligament (ACL) is the primary stabilizer of the knee. An impairment of any of the dynamic or static stability providing factors can lead to overload on the other factors and ultimately to deterioration of knee stability. This can result in anterior tibial translation and rupture of the ACL. The purpose of this study was to examine the influence of tibial slope on ACL injury risk on soccer players. A total of 64 elite soccer players and 45 sedentary controls were included in this longitudinal and controlled study. The angle between the tibial mid-diaphysis line and the line between the anterior and posterior edges of the medial tibial plateau was measured as the tibial slope via lateral radiographs. Individual player exposure, and injuries sustained by the participants were prospectively recorded. Eleven ACL injuries were documented during the study period. Tibial slope was not different between soccer players and sedentary controls. Tibial slope in the dominant and non-dominant legs was greater for the injured players compared to the uninjured players. The difference reached a significant level only for the dominant legs (p < 0.001). While the tibial slopes of the dominant and non-dominant legs were not different on uninjured players (p > 0.05), a higher tibial slope was observed in dominant legs of injured players (p < 0.05). Higher tibial slope on injured soccer players compared to the uninjured ones supports the idea that the tibial slope degree might be an important risk factor for ACL injury. Key pointsDominant legs' tibial slopes of the injured players were significantly higher compared to the uninjured players (p < 0.001).Higher tibial slope was determined in dominant legs compared to the non-dominant side, for the injured players (p = 0.042). Different tibial slope measures in dominant and non-dominant legs might be the result of different loading and/or adaptation patterns in soccer.

Inducing any virtual two-dimensional movement in humans by applying muscle tendon vibration.

PubMed

Roll, Jean-Pierre; Albert, Frédéric; Thyrion, Chloé; Ribot-Ciscar, Edith; Bergenheim, Mikael; Mattei, Benjamin

2009-02-01

In humans, tendon vibration evokes illusory sensation of movement. We developed a model mimicking the muscle afferent patterns corresponding to any two-dimensional movement and checked its validity by inducing writing illusory movements through specific sets of muscle vibrators. Three kinds of illusory movements were compared. The first was induced by vibration patterns copying the responses of muscle spindle afferents previously recorded by microneurography during imposed ankle movements. The two others were generated by the model. Sixteen different vibratory patterns were applied to 20 motionless volunteers in the absence of vision. After each vibration sequence, the participants were asked to name the corresponding graphic symbol and then to reproduce the illusory movement perceived. Results showed that the afferent patterns generated by the model were very similar to those recorded microneurographically during actual ankle movements (r=0.82). The model was also very efficient for generating afferent response patterns at the wrist level, if the preferred sensory directions of the wrist muscle groups were first specified. Using recorded and modeled proprioceptive patterns to pilot sets of vibrators placed at the ankle or wrist levels evoked similar illusory movements, which were correctly identified by the participants in three quarters of the trials. Our proprioceptive model, based on neurosensory data recorded in behaving humans, should then be a useful tool in fields of research such as sensorimotor learning, rehabilitation, and virtual reality.

Creatine supplementation in high school football players.

PubMed

McGuine, T A; Sullivan, J C; Bernhardt, D T

2001-10-01

To describe creatine supplementation patterns and behaviors associated with creatine supplementation in high school football players. A cross-sectional, multisite, anonymous, descriptive survey was conducted between October 1999 and February 2000. 37 public high schools in Wisconsin. A total of 1,349 high school football players, grades 9-12. Self-reported prevalence of creatine use, as well as perceived benefits and risks. In addition, sources of information and influence regarding creatine supplementation were assessed. 30% of the respondents reported using creatine. Creatine use was lowest in the 9th grade (10.4%) and highest in the 12th grade (50.5%). 41% of the players at small schools stated they used creatine compared with 29% of the players in large schools. Enhanced recovery following a workout was the most likely perceived benefit of creatine supplementation, while dehydration was cited most often as a risk of creatine use. Users were encouraged to take creatine most often by their friends while their parents discouraged creatine use. Creatine use is widespread in high school football players. High school football players who use creatine may not be aware of the risks and benefits associated with creatine supplementation. Sports medicine professionals who work with this population need to educate athletes, coaches, and parents about the use of creatine as a performance-enhancing supplement.

Fusing visual and behavioral cues for modeling user experience in games.

PubMed

Shaker, Noor; Asteriadis, Stylianos; Yannakakis, Georgios N; Karpouzis, Kostas

2013-12-01

Estimating affective and cognitive states in conditions of rich human-computer interaction, such as in games, is a field of growing academic and commercial interest. Entertainment and serious games can benefit from recent advances in the field as, having access to predictors of the current state of the player (or learner) can provide useful information for feeding adaptation mechanisms that aim to maximize engagement or learning effects. In this paper, we introduce a large data corpus derived from 58 participants that play the popular Super Mario Bros platform game and attempt to create accurate models of player experience for this game genre. Within the view of the current research, features extracted both from player gameplay behavior and game levels, and player visual characteristics have been used as potential indicators of reported affect expressed as pairwise preferences between different game sessions. Using neuroevolutionary preference learning and automatic feature selection, highly accurate models of reported engagement, frustration, and challenge are constructed (model accuracies reach 91%, 92%, and 88% for engagement, frustration, and challenge, respectively). As a step further, the derived player experience models can be used to personalize the game level to desired levels of engagement, frustration, and challenge as game content is mapped to player experience through the behavioral and expressivity patterns of each player.

Game-Based Approaches' Pedagogical Principles: Exploring Task Constraints in Youth Soccer.

PubMed

Serra-Olivares, Jaime; González-Víllora, Sixto; García-López, Luis Miguel; Araújo, Duarte

2015-06-27

This study tested the use of two pedagogical principles of Game-based approaches, representation and exaggeration, in the context of game performance of U10 soccer players. Twenty-one players participated in two 3 vs. 3 small-sided games. The first small-sided game was modified by representation. The second small-sided game was modified by enhancing the penetration of the defense tactical problem for invasion games. Decision-making and execution were assessed using the Game Performance Evaluation Tool. No significant differences were observed between games in the number of decision-making units related to keeping possession, nor in those related to penetrating the defense. No significant differences were observed in any execution ability (ball control, passing, dribbling and get free movements). The findings suggested that both games could provide similar degeneracy processes to the players for skill acquisition (specific and contextualized task constraints in which they could develop their game performance and the capability to achieve different outcomes in varying contexts). Probably both games had similar learner-environment dynamics leading players to develop their capabilities for adapting their behaviours to the changing performance situations. More research is necessary, from the ecological dynamics point of view, to determine how we should use small-sided games in Game-based approaches.

Throwing velocity and kinematics in elite male water polo players.

PubMed

Melchiorri, G; Padua, E; Padulo, J; D'Ottavio, S; Campagna, S; Bonifazi, M

2011-12-01

Fifty-three members of the Italian Men Water Polo Team were filmed using two synchronized cameras, while they were shooting a goal. Considering the differences in body mass, height, training strategies and the technical-tactical features of the players, the aims of this study were to employ video-analysis techniques in order to investigate selected kinematic parameters in water polo throwing, and to provide comprehensive quantitative information on the throwing movement in relation to the different team player positions. Video analysis was used to estimate the elbow angle at release, the shoulder angle at follow through, the back and head height at ball release, trunk rotation angle and ball velocity at release. Ball release velocities ranged from 21.0 to 29.8 m/s (average value 25.3±1.4 m/s), for field players. Goal keepers show the lowest team values (average 21.7±0.3 m/s). Similar to previous study results, ball release was typically reached just prior to the elbow approaching full extension (151.6±3.6°), and the follow through shoulder angle was 143±5.9°. No significant statistical difference was recorded between injured and non-injured athletes. No positive association was demonstrated between physical characteristics (body mass and height) and ball velocity.

Changes in practice task constraints shape decision-making behaviours of team games players.

PubMed

Correia, Vanda; Araújo, Duarte; Duarte, Ricardo; Travassos, Bruno; Passos, Pedro; Davids, Keith

2012-05-01

This study examined the effects of manipulating relative positioning between defenders (initial distance apart) on emergent decision-making and actions in a 1 vs. 2 rugby union performance sub-phase. Twelve experienced youth players performed 80 trials of a 1 (attacker) vs. 2 (defenders) practice task in which the starting distance between defenders was systematically decreased. Movement displacement trajectories of participants were video recorded to obtain 2D positional data. The independent variable was the starting distance between defenders and dependent variables were: (i) performance outcome (try or tackle), (ii) mean speed of all players during performance, and (iii), time between the first crossover and the end of the trial. Repeated measures ANOVA was used to compare the effects of different starting distances on performance. Shorter starting distances between defenders were associated with a higher frequency of effective tackle outcomes, lower mean speeds of all participants, and a greater time period between the first crossover and the end of the trial. Decision-making behaviours emerged as a function of changes in participants' spatial location during performance. This observation supports the importance of manipulating key spatial-temporal variables in designing representative practice task constraints that induce functional player-environment interactions in team sports training. Copyright © 2011 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Game-Based Approaches’ Pedagogical Principles: Exploring Task Constraints in Youth Soccer

PubMed Central

Serra-Olivares, Jaime; González-Víllora, Sixto; García-López, Luis Miguel; Araújo, Duarte

2015-01-01

This study tested the use of two pedagogical principles of Game-based approaches, representation and exaggeration, in the context of game performance of U10 soccer players. Twenty-one players participated in two 3 vs. 3 small-sided games. The first small-sided game was modified by representation. The second small-sided game was modified by enhancing the penetration of the defense tactical problem for invasion games. Decision-making and execution were assessed using the Game Performance Evaluation Tool. No significant differences were observed between games in the number of decision-making units related to keeping possession, nor in those related to penetrating the defense. No significant differences were observed in any execution ability (ball control, passing, dribbling and get free movements). The findings suggested that both games could provide similar degeneracy processes to the players for skill acquisition (specific and contextualized task constraints in which they could develop their game performance and the capability to achieve different outcomes in varying contexts). Probably both games had similar learner-environment dynamics leading players to develop their capabilities for adapting their behaviours to the changing performance situations. More research is necessary, from the ecological dynamics point of view, to determine how we should use small-sided games in Game-based approaches. PMID:26240668

Effects of plyometric training on soccer players

PubMed Central

Wang, Ying-Chun; Zhang, Na

2016-01-01

Plyometric training (PT) is a technique used to increase strength and explosiveness. It consists of physical exercises in which muscles exert maximum force at short intervals to increase dynamic performances. In such a training, muscles undergo a rapid elongation followed by an immediate shortening (stretch-shortening contraction), utilizing the elastic energy stored during the stretching phase. There is consensus on the fact that when used, PT contributes to improvement in vertical jump performance, acceleration, leg strength, muscular power, increase of joint awareness and overall sport-specific skills. Consequently, PT which was primarily used by martial artists, sprinters and high jumpers to improve performances has gained in popularity and has been used by athletes in all types of sports. However, although PT has been shown to increase performance variables in many sports, little scientific information is currently available to determine whether PT actually enhances skill performance in soccer players, considering that soccer is an extremely demanding sport. Soccer players require dynamic muscular performance for fighting at all levels of training status, including rapid movements such as acceleration and deceleration of the body, change of direction, vertical and horizontal jumps, endurance, speed as well as power for kicking and tackling. In this review we discussed the effects of PT on soccer players by considering gender and age categories. PMID:27446242

Aerobic conditioning for team sport athletes.

PubMed

Stone, Nicholas M; Kilding, Andrew E

2009-01-01

Team sport athletes require a high level of aerobic fitness in order to generate and maintain power output during repeated high-intensity efforts and to recover. Research to date suggests that these components can be increased by regularly performing aerobic conditioning. Traditional aerobic conditioning, with minimal changes of direction and no skill component, has been demonstrated to effectively increase aerobic function within a 4- to 10-week period in team sport players. More importantly, traditional aerobic conditioning methods have been shown to increase team sport performance substantially. Many team sports require the upkeep of both aerobic fitness and sport-specific skills during a lengthy competitive season. Classic team sport trainings have been shown to evoke marginal increases/decreases in aerobic fitness. In recent years, aerobic conditioning methods have been designed to allow adequate intensities to be achieved to induce improvements in aerobic fitness whilst incorporating movement-specific and skill-specific tasks, e.g. small-sided games and dribbling circuits. Such 'sport-specific' conditioning methods have been demonstrated to promote increases in aerobic fitness, though careful consideration of player skill levels, current fitness, player numbers, field dimensions, game rules and availability of player encouragement is required. Whilst different conditioning methods appear equivalent in their ability to improve fitness, whether sport-specific conditioning is superior to other methods at improving actual game performance statistics requires further research.

Individual Movement Strategies Revealed through Novel Clustering of Emergent Movement Patterns

NASA Astrophysics Data System (ADS)

Valle, Denis; Cvetojevic, Sreten; Robertson, Ellen P.; Reichert, Brian E.; Hochmair, Hartwig H.; Fletcher, Robert J.

2017-03-01

Understanding movement is critical in several disciplines but analysis methods often neglect key information by adopting each location as sampling unit, rather than each individual. We introduce a novel statistical method that, by focusing on individuals, enables better identification of temporal dynamics of connectivity, traits of individuals that explain emergent movement patterns, and sites that play a critical role in connecting subpopulations. We apply this method to two examples that span movement networks that vary considerably in size and questions: movements of an endangered raptor, the snail kite (Rostrhamus sociabilis plumbeus), and human movement in Florida inferred from Twitter. For snail kites, our method reveals substantial differences in movement strategies for different bird cohorts and temporal changes in connectivity driven by the invasion of an exotic food resource, illustrating the challenge of identifying critical connectivity sites for conservation in the presence of global change. For human movement, our method is able to reliably determine the origin of Florida visitors and identify distinct movement patterns within Florida for visitors from different places, providing near real-time information on the spatial and temporal patterns of tourists. These results emphasize the need to integrate individual variation to generate new insights when modeling movement data.

PA03.05. Masha taila as a preventive measure in gulpha marma injuries.

PubMed Central

Dhaded, Rajani; Kulkarni, BG

2013-01-01

Purpose: In Basketball game Gulpha Marma injuries are common. Wrong landing causes inflammation & tearing of ligament resulting into sprain. Prevention can be carried out by protective wears like Ankelet,crape bandge which gives temporary recovery. Assessment and evaluation of the application of Masha Taila as a Snehana and Avagaha Sweda as a preventive measure for Gulpha Marma injuries. Method: 30 players with Normal ankle joint (Group A) & 30 players with Ankle sprain (1st degree) of Basketball players (Group B) were taken with age group 13 to 25 yrs. Goniometer to measure Range of motion (R.O.M.), pain analog scale for pain gradation. Result: Group A and B were compared with their control groups. The statistical result for normal dorsiflexion was 0.0007 degree, plantar flexion 0.001 degree, dorsi flexion of ankle sprain players 0.002 degree, plantar flexion 0.03 degree. The measurement of ROM of all players increased by 510 times indicating increased joint flexibility, based on ROM Mash taila proved to be a preventive measure. Pain analog scale for group B players indicated moderate pain at 0 day,reduced by 50% on 15th day and completely reduced on 30th day. Conclusion: “Prevention is better than cure”. As a preventive aspect the application of Masha Taila in normal ankle joint as Snehan & Swedan with warm water increases flexibility of joint and muscle strength. In sprained joint the same Taila application relives pain and regains its movements, this recovery and strength of joints happens because of reduce adhesion & influence the direction of new collage fibres in the healing process. It eliminates toxic accumulation from secondary muscle spasm. These Marma being the vital points must be prevented by applying Snehan & Swedan before starting the game just as warm up.

Free-Weight Augmentation With Elastic Bands Improves Bench Press Kinematics in Professional Rugby Players.

PubMed

García-López, David; Hernández-Sánchez, Sonsoles; Martín, Esperanza; Marín, Pedro J; Zarzosa, Fernando; Herrero, Azael J

2016-09-01

García-López, D, Hernández-Sánchez, S, Martín, E, Marín, PJ, Zarzosa, F, and Herrero, AJ. Free-weight augmentation with elastic bands improves bench press kinematics in professional rugby players. J Strength Cond Res 30(9): 2493-2499, 2016-This study aimed to investigate the effects of combining elastic bands to free weight resistance (EB + FWR) on the acceleration-deceleration and velocity profiles of the bench press in professional rugby players and recreationally trained subjects. Sixteen male subjects (8 rugby players and 8 recreationally trained subjects) were randomly assigned to complete 2 experimental conditions in a crossover fashion: EB + FWR and FWR. In both conditions, subjects performed 1 bench press set to volitional exhaustion with a load equivalent to the 85% of 1 repetition maximum (1RM). In the EB + FWR condition, the contribution of elastic resistance was approximately 20% of the selected load (85% 1RM). Results indicate that EB + FWR condition increased significantly the range of concentric movement in which the barbell is accelerated. This increase was significantly higher in rugby players (35%) in comparison with recreationally trained subjects (13%). Maximal velocity was also increased in EB + FWR (17%), when compared with FWR condition. These results suggest that when combined with variable resistance (i.e., EB), the external resistance seems to be more evenly distributed over the full range of motion, decreasing the need for dramatic deceleration at the end of the concentric phase. The present data also indicate that the kinematic benefits of an EB + FWR approach seems to be more prominent in athletes from modalities in which high level of strength and power are required (i.e., rugby players).

Understanding eye movements in face recognition using hidden Markov models.

PubMed

Chuk, Tim; Chan, Antoni B; Hsiao, Janet H

2014-09-16

We use a hidden Markov model (HMM) based approach to analyze eye movement data in face recognition. HMMs are statistical models that are specialized in handling time-series data. We conducted a face recognition task with Asian participants, and model each participant's eye movement pattern with an HMM, which summarized the participant's scan paths in face recognition with both regions of interest and the transition probabilities among them. By clustering these HMMs, we showed that participants' eye movements could be categorized into holistic or analytic patterns, demonstrating significant individual differences even within the same culture. Participants with the analytic pattern had longer response times, but did not differ significantly in recognition accuracy from those with the holistic pattern. We also found that correct and wrong recognitions were associated with distinctive eye movement patterns; the difference between the two patterns lies in the transitions rather than locations of the fixations alone. © 2014 ARVO.

Convergence of marine megafauna movement patterns in coastal and open oceans.

PubMed

Sequeira, A M M; Rodríguez, J P; Eguíluz, V M; Harcourt, R; Hindell, M; Sims, D W; Duarte, C M; Costa, D P; Fernández-Gracia, J; Ferreira, L C; Hays, G C; Heupel, M R; Meekan, M G; Aven, A; Bailleul, F; Baylis, A M M; Berumen, M L; Braun, C D; Burns, J; Caley, M J; Campbell, R; Carmichael, R H; Clua, E; Einoder, L D; Friedlaender, Ari; Goebel, M E; Goldsworthy, S D; Guinet, C; Gunn, J; Hamer, D; Hammerschlag, N; Hammill, M; Hückstädt, L A; Humphries, N E; Lea, M-A; Lowther, A; Mackay, A; McHuron, E; McKenzie, J; McLeay, L; McMahon, C R; Mengersen, K; Muelbert, M M C; Pagano, A M; Page, B; Queiroz, N; Robinson, P W; Shaffer, S A; Shivji, M; Skomal, G B; Thorrold, S R; Villegas-Amtmann, S; Weise, M; Wells, R; Wetherbee, B; Wiebkin, A; Wienecke, B; Thums, M

2018-03-20

The extent of increasing anthropogenic impacts on large marine vertebrates partly depends on the animals' movement patterns. Effective conservation requires identification of the key drivers of movement including intrinsic properties and extrinsic constraints associated with the dynamic nature of the environments the animals inhabit. However, the relative importance of intrinsic versus extrinsic factors remains elusive. We analyze a global dataset of ∼2.8 million locations from >2,600 tracked individuals across 50 marine vertebrates evolutionarily separated by millions of years and using different locomotion modes (fly, swim, walk/paddle). Strikingly, movement patterns show a remarkable convergence, being strongly conserved across species and independent of body length and mass, despite these traits ranging over 10 orders of magnitude among the species studied. This represents a fundamental difference between marine and terrestrial vertebrates not previously identified, likely linked to the reduced costs of locomotion in water. Movement patterns were primarily explained by the interaction between species-specific traits and the habitat(s) they move through, resulting in complex movement patterns when moving close to coasts compared with more predictable patterns when moving in open oceans. This distinct difference may be associated with greater complexity within coastal microhabitats, highlighting a critical role of preferred habitat in shaping marine vertebrate global movements. Efforts to develop understanding of the characteristics of vertebrate movement should consider the habitat(s) through which they move to identify how movement patterns will alter with forecasted severe ocean changes, such as reduced Arctic sea ice cover, sea level rise, and declining oxygen content.

Glial activation in the collagenase model of nociception associated with osteoarthritis.

PubMed

Adães, Sara; Almeida, Lígia; Potes, Catarina S; Ferreira, Ana Rita; Castro-Lopes, José M; Ferreira-Gomes, Joana; Neto, Fani L

2017-01-01

Background Experimental osteoarthritis entails neuropathic-like changes in dorsal root ganglia (DRG) neurons. Since glial activation has emerged as a key player in nociception, being reported in numerous models of neuropathic pain, we aimed at evaluating if glial cell activation may also occur in the DRG and spinal cord of rats with osteoarthritis induced by intra-articular injection of collagenase. Methods Osteoarthritis was induced by two injections, separated by three days, of 500 U of type II collagenase into the knee joint of rats. Movement-induced nociception was evaluated by the Knee-Bend and CatWalk tests during the following six weeks. Glial fibrillary acidic protein (GFAP) expression in satellite glial cells of the DRG was assessed by immunofluorescence and Western Blot analysis; the pattern of GFAP and activating transcription factor-3 (ATF-3) expression was also compared through double immunofluorescence analysis. GFAP expression in astrocytes and IBA-1 expression in microglia of the L3-L5 spinal cord segments was assessed by immunohistochemistry and Western Blot analysis. The effect of the intrathecal administration of fluorocitrate, an inhibitor of glial activation, on movement-induced nociception was evaluated six weeks after the first collagenase injection. Results GFAP expression in satellite glial cells of collagenase-injected animals was significantly increased six weeks after osteoarthritis induction. Double immunofluorescence showed GFAP upregulation in satellite glial cells surrounding ATF-3-positive neurons. In the spinal cord of collagenase-injected animals, an ipsilateral upregulation of GFAP and IBA-1 was also observed. The inhibition of glial activation with fluorocitrate decreased movement- and loading-induced nociception. Conclusion Collagenase-induced knee osteoarthritis leads to the development of nociception associated with movement of the affected joint and to the activation of glial cells in both the DRG and the spinal cord. Inhibition of glial cell activation by fluorocitrate decreases these osteoarthritis-associated nociceptive behaviours. These results suggest that glial cell activation may play a role in the development of chronic pain in this experimental model of osteoarthritis.

Roles of Social Movement Organizations for Securing Workers' Safety in Korea: A Case Study of Abolition of the 30-Minute Delivery Guarantee Program in Pizza Delivery Service.

PubMed

Park, Ji-Eun; Kim, Myoung-Hee

2016-07-01

Many restaurants in Korea maintain quick-delivery service programs to satisfy customers. This service allows delivery workers limited time to deliver, which frequently put them in danger. Most of the workers are young, work part-time, and are rarely organized into trade unions. In this article, through a case study of the social movement to abolish the 30-minute delivery guarantee program of pizza companies in Korea, we argue that social movements involving social movement organizations (SMOs) and individual citizens could serve as a means to rectify this problem. We show how the SMOs developed and expanded the movement using a framing perspective and how the general public became involved through social media. Data was collected via online searching. Interview scripts from key players of SMOs and unofficial documents they provided were also reviewed. Three SMOs primarily led the movement, successfully forming a frame that emphasized social responsibility. SMOs also utilized social media to link their standing frame with unmobilized citizens and to expand the movement. We identified contributing factors and limitations of the movement and drew lessons that could be applied to other sectors where workers are in vulnerable positions. © The Author(s) 2016.

Lower extremity muscle function of front row rugby union scrummaging.

PubMed

Yaghoubi, Mostafa; Lark, Sally D; Page, Wyatt H; Fink, Philip W; Shultz, Sarah P

2018-05-16

A rugby scrum's front row must act uniformly to transfer maximal horizontal force and improve performance. This study investigated the muscle activation patterns of lower extremity muscles in front row forwards during live and machine scrums at professional and amateur levels. Electromyography was collected bilaterally on vastus lateralis, rectus femoris and gastrocnemius muscles of 75 male rugby prop players during live and machine scrums. ANOVAs compared muscle reaction time, rate of change in muscle amplitude and muscle amplitude between groups and conditions. Cross-correlation analysis explored muscle synchronicity. There were significantly greater rates of change in each muscle amplitude in professional players than amateur players. Additionally, there was significantly quicker muscle reaction time in all muscles, and greater amplitude in vastus lateralis and gastrocnemius, during the live scrum vs. machine condition. The professional props produced more synchronised muscle activation than amateur players and all players produced more synchronised muscle activation against the scrum machine vs. live scrummage. The results indicate a higher skill proficiency and muscle synchronicity in professional players. While scrum machine training is ideally suited for functional muscle strengthening during practice, to truly simulate the requirements of the scrum, training should incorporate the live situation as much as possible.

Social network analysis of the movement of poultry to and from live bird markets in Bali and Lombok, Indonesia.

PubMed

Kurscheid, J; Stevenson, M; Durr, P A; Toribio, J-A L M L; Kurscheid, S; Ambarawati, I G A A; Abdurrahman, M; Fenwick, S

2017-12-01

Highly pathogenic avian influenza H5N1 has resulted in large losses to the Indonesian poultry sector. Evidence suggests that live bird markets (LBMs) play an important role in the epidemiology of the disease. Knowledge of the frequency and type of contact between the various poultry market players should allow animal health authorities to develop a better understanding of factors influencing virus transmission between Indonesian villages. A questionnaire-based cross-sectional survey was conducted in 17 LBMs on the neighbouring Indonesian islands of Bali and Lombok to investigate the movement patterns of poultry to and from markets. Using social network analyses, a network of contacts was created for each island from a total of 413 live poultry traders and 134 customers. Individual nodes with high degree and/or betweenness were identified in each network. The Lombok network was more dense and connected than the Bali network indicating that disease transmission would be more efficient in the Lombok network. Our findings indicate that whilst live poultry are typically transported over relatively short distances of approximately 10 km, it is not uncommon for traders and customers to travel in excess of 100 km to buy or sell poultry, which may facilitate the spread of disease over a large geographical area. This study highlights the different roles markets play in poultry movement networks and their potential for disease dissemination. The identification of highly influential market nodes allows authorities to target HPAI surveillance activities to locations where disease is more likely to be present, which is crucial in low-resource settings. © 2017 Blackwell Verlag GmbH.

Chess knowledge predicts chess memory even after controlling for chess experience: Evidence for the role of high-level processes.

PubMed

Lane, David M; Chang, Yu-Hsuan A

2018-04-01

The expertise effect in memory for chess positions is one of the most robust effects in cognitive psychology. One explanation of this effect is that chess recall is based on the recognition of familiar patterns and that experts have learned more and larger patterns. Template theory and its instantiation as a computational model are based on this explanation. An alternative explanation is that the expertise effect is due, in part, to stronger players having better and more conceptual knowledge, with this knowledge facilitating memory performance. Our literature review supports the latter view. In our experiment, a sample of 79 chess players were given a test of memory for chess positions, a test of declarative chess knowledge, a test of fluid intelligence, and a questionnaire concerning the amount of time they had played nontournament chess and the amount of time they had studied chess. We determined the numbers of tournament games the players had played from chess databases. Chess knowledge correlated .67 with chess memory and accounted for 16% of the variance after controlling for chess experience. Fluid intelligence accounted for an additional 13% of the variance. These results support the conclusion that both high-level conceptual processing and low-level recognition of familiar patterns play important roles in memory for chess positions.

Coordination analysis of players' distribution in football using cross-correlation and vector coding techniques.

PubMed

Moura, Felipe Arruda; van Emmerik, Richard E A; Santana, Juliana Exel; Martins, Luiz Eduardo Barreto; Barros, Ricardo Machado Leite de; Cunha, Sergio Augusto

2016-12-01

The purpose of this study was to investigate the coordination between teams spread during football matches using cross-correlation and vector coding techniques. Using a video-based tracking system, we obtained the trajectories of 257 players during 10 matches. Team spread was calculated as functions of time. For a general coordination description, we calculated the cross-correlation between the signals. Vector coding was used to identify the coordination patterns between teams during offensive sequences that ended in shots on goal or defensive tackles. Cross-correlation showed that opponent teams have a tendency to present in-phase coordination, with a short time lag. During offensive sequences, vector coding results showed that, although in-phase coordination dominated, other patterns were observed. We verified that during the early stages, offensive sequences ending in shots on goal present greater anti-phase and attacking team phase periods, compared to sequences ending in tackles. Results suggest that the attacking team may seek to present a contrary behaviour of its opponent (or may lead the adversary behaviour) in the beginning of the attacking play, regarding to the distribution strategy, to increase the chances of a shot on goal. The techniques allowed detecting the coordination patterns between teams, providing additional information about football dynamics and players' interaction.

The Specificity of Rugby Union Training Sessions in Preparation for Match Demands.

PubMed

Campbell, Patrick G; Peake, Jonathan M; Minett, Geoffrey M

2018-04-01

Investigations into the specificity of rugby union training practices in preparation for competitive demands have predominantly focused on physical and physiological demands. The evaluation of the contextual variance in perceptual strain or skill requirements between training and matches in rugby union is unclear, yet holistic understanding may assist to optimize training design. This study evaluated the specificity of physical, physiological, perceptual, and skill demands of training sessions compared with competitive match play in preprofessional, elite club rugby union. Global positioning system devices, video capture, heart rate, and session ratings of perceived exertion were used to assess movement patterns, skill completions, physiologic, and perceptual responses, respectively. Data were collected across a season (training sessions n = 29; matches n = 14). Participants (n = 32) were grouped in playing positions as: outside backs, centers, halves, loose forwards, lock forwards, and front row forwards. Greater total distance, low-intensity activity, maximal speed, and meters per minute were apparent in matches compared with training in all positions (P < .02; d > 0.90). Similarly, match heart rate and session ratings of perceived exertion responses were higher than those recorded in training (P < .05; d > 0.8). Key skill completions for forwards (ie, scrums, rucks, and lineouts) and backs (ie, kicks) were greater under match conditions than in training (P < .001; d > 1.50). Considerable disparities exist between the perceptual, physiological, and key skill demands of competitive matches versus training sessions in preprofessional rugby union players. Practitioners should consider the specificity of training tasks for preprofessional rugby players to ensure the best preparation for match demands.

From degree-correlated to payoff-correlated activity for an optimal resolution of social dilemmas

NASA Astrophysics Data System (ADS)

Aleta, Alberto; Meloni, Sandro; Perc, Matjaž; Moreno, Yamir

2016-12-01

An active participation of players in evolutionary games depends on several factors, ranging from personal stakes to the properties of the interaction network. Diverse activity patterns thus have to be taken into account when studying the evolution of cooperation in social dilemmas. Here we study the weak prisoner's dilemma game, where the activity of each player is determined in a probabilistic manner either by its degree or by its payoff. While degree-correlated activity introduces cascading failures of cooperation that are particularly severe on scale-free networks with frequently inactive hubs, payoff-correlated activity provides a more nuanced activity profile, which ultimately hinders systemic breakdowns of cooperation. To determine optimal conditions for the evolution of cooperation, we introduce an exponential decay to payoff-correlated activity that determines how fast the activity of a player returns to its default state. We show that there exists an intermediate decay rate at which the resolution of the social dilemma is optimal. This can be explained by the emerging activity patterns of players, where the inactivity of hubs is compensated effectively by the increased activity of average-degree players, who through their collective influence in the network sustain a higher level of cooperation. The sudden drops in the fraction of cooperators observed with degree-correlated activity therefore vanish, and so does the need for the lengthy spatiotemporal reorganization of compact cooperative clusters. The absence of such asymmetric dynamic instabilities thus leads to an optimal resolution of social dilemmas, especially when the conditions for the evolution of cooperation are strongly adverse.

Multiparametric MRI changes persist beyond recovery in concussed adolescent hockey players

PubMed Central

Manning, Kathryn Y.; Schranz, Amy; Bartha, Robert; Dekaban, Gregory A.; Barreira, Christy; Brown, Arthur; Fischer, Lisa; Asem, Kevin; Doherty, Timothy J.; Fraser, Douglas D.; Holmes, Jeff

2017-01-01

Objective: To determine whether multiparametric MRI data can provide insight into the acute and long-lasting neuronal sequelae after a concussion in adolescent athletes. Methods: Players were recruited from Bantam hockey leagues in which body checking is first introduced (male, age 11–14 years). Clinical measures, diffusion metrics, resting-state network and region-to-region functional connectivity patterns, and magnetic resonance spectroscopy absolute metabolite concentrations were analyzed from an independent, age-matched control group of hockey players (n = 26) and longitudinally in concussed athletes within 24 to 72 hours (n = 17) and 3 months (n = 14) after a diagnosed concussion. Results: There were diffusion abnormalities within multiple white matter tracts, functional hyperconnectivity, and decreases in choline 3 months after concussion. Tract-specific spatial statistics revealed a large region along the superior longitudinal fasciculus with the largest decreases in diffusivity measures, which significantly correlated with clinical deficits. This region also spatially intersected with probabilistic tracts connecting cortical regions where we found acute functional connectivity changes. Hyperconnectivity patterns at 3 months after concussion were present only in players with relatively less severe clinical outcomes, higher choline concentrations, and diffusivity indicative of relatively less axonal disruption. Conclusions: Changes persisted well after players' clinical scores had returned to normal and they had been cleared to return to play. Ongoing white matter maturation may make adolescent athletes particularly vulnerable to brain injury, and they may require extended recovery periods. The consequences of early brain injury for ongoing brain development and risk of more serious conditions such as second impact syndrome or neural degenerative processes need to be elucidated. PMID:29070666

Match injuries in English youth academy and schools rugby union: an epidemiological study.

PubMed

Palmer-Green, Deborah S; Stokes, Keith A; Fuller, Colin W; England, Michael; Kemp, Simon P T; Trewartha, Grant

2013-04-01

Numerous injury epidemiology studies have reported injury patterns in senior rugby union, but investigations in youth rugby are limited. To describe the nature of injuries resulting from match play within the English youth rugby union, including a comparison between 2 levels of play within the same age group: professional academy versus school rugby. Cohort study; Level of evidence, 2. A 2-season (2006-2007 and 2007-2008) study obtained information on injuries sustained in male youth rugby union players (age, 16-18 years) from 12 English Premiership academies (n = 250) and 7 schools (n = 222). Match exposure (player-hours) and injury details were recorded. Match injury incidence was 47 per 1000 player-hours for the academy and 35 per 1000 player-hours for the school groups; these rates were statistically different (P = .026). The most common injury site was the lower limb and the most common injury type was a ligament sprain, with injuries to the knee and shoulder region resulting in the greatest burden of injury for both groups. The tackle event was the most common cause of match injury for both academy (51% of injuries) and school (57% of injuries) groups. Overall, the incidence of injury for youth rugby was lower than for previous studies in senior rugby, but injury patterns (location, type) and causes were similar. The study confirmed that match injury incidence was significantly greater in elite academy youth rugby union than schools rugby. The results suggest that the specific focus for injury risk management in youth rugby should be on players' tackle technique and prevention strategies for knee and shoulder injuries.

Seasonal Mood Disturbances in Collegiate Hockey Players

PubMed Central

Rosen, Lionel W.; Shafer, Christine L.; Smokler, Carol; Carrier, David; McKeag, Douglas B.

1996-01-01

Objective: The purpose of this paper is to: 1) describe the seasonal affective disorder syndrome using a case illustration, 2) provide a simple and reliable method for identifying seasonal affective disorder, and 3) provide data as to the prevalence of the syndrome in a subset of collegiate hockey players. Design and Setting: Collegiate hockey players were selected, because their practices begin in the fall and play is completed in the spring. The teams selected for participation were from the far Northwest and the upper Midwest regions. Subjects: Sixty-eight Division I hockey players volunteered for the study. The three teams from which the subjects were chosen were located above latitude 42°/45' north. Subjects were from the northern latitudes. Measurements: The Seasonal Pattern Assessment Questionnaire was used to screen for seasonality. A sample of the athletes was also examined using the Hamilton Rating Scale for Depression together with the Diagnostic and Statistical Manual of Mental Disorders (4th ed) criteria for Seasonal Pattern Specifier. Results: Thirty-three (51%) were asymptomatic, 7 (11%) met the criteria for seasonal affective disorder, and 25 (39%) hockey players scored in the range that could classify them as candidates for subsyndromal seasonal affective disorder. Conclusions: The prevalence of seasonal affective disorder among our sample approximated the national norm for the northern latitudes. However, the prevalence of subsyndromal seasonal affective disorder in our population was 25% compared to 13% reported nationally. Light therapy has been shown to reverse the effects of the disorders; however, further research needs to be conducted to determine its acceptance and effectiveness by the athletic population. PMID:16558403

Movement pattern recognition in basketball free-throw shooting.

PubMed

Schmidt, Andrea

2012-04-01

The purpose of the present study was to analyze the movement patterns of free-throw shooters in basketball at different skill levels. There were two points of interest. First, to explore what information can be drawn from the movement pattern and second, to examine the methodological possibilities of pattern analysis. To this end, several qualitative and quantitative methods were employed. The resulting data were converged in a triangulation. Using a special kind of ANN named Dynamically Controlled Networks (DyCoN), a 'complex feature' consisting of several isolated features (angle displacements and velocities of the articulations of the kinematic chain) was calculated. This 'complex feature' was displayed by a trajectory combining several neurons of the network, reflecting the devolution of the twelve angle measures over the time course of each shooting action. In further network analyses individual characteristics were detected, as well as movement phases. Throwing patterns were successfully classified and the stability and variability of the realized pattern were established. The movement patterns found were clearly individually shaped as well as formed by the skill level. The triangulation confirmed the individual movement organizations. Finally, a high stability of the network methods was documented. Copyright © 2012. Published by Elsevier B.V.

Is having similar eye movement patterns during face learning and recognition beneficial for recognition performance? Evidence from hidden Markov modeling.

PubMed

Chuk, Tim; Chan, Antoni B; Hsiao, Janet H

2017-12-01

The hidden Markov model (HMM)-based approach for eye movement analysis is able to reflect individual differences in both spatial and temporal aspects of eye movements. Here we used this approach to understand the relationship between eye movements during face learning and recognition, and its association with recognition performance. We discovered holistic (i.e., mainly looking at the face center) and analytic (i.e., specifically looking at the two eyes in addition to the face center) patterns during both learning and recognition. Although for both learning and recognition, participants who adopted analytic patterns had better recognition performance than those with holistic patterns, a significant positive correlation between the likelihood of participants' patterns being classified as analytic and their recognition performance was only observed during recognition. Significantly more participants adopted holistic patterns during learning than recognition. Interestingly, about 40% of the participants used different patterns between learning and recognition, and among them 90% switched their patterns from holistic at learning to analytic at recognition. In contrast to the scan path theory, which posits that eye movements during learning have to be recapitulated during recognition for the recognition to be successful, participants who used the same or different patterns during learning and recognition did not differ in recognition performance. The similarity between their learning and recognition eye movement patterns also did not correlate with their recognition performance. These findings suggested that perceptuomotor memory elicited by eye movement patterns during learning does not play an important role in recognition. In contrast, the retrieval of diagnostic information for recognition, such as the eyes for face recognition, is a better predictor for recognition performance. Copyright © 2017 Elsevier Ltd. All rights reserved.

Injury incidence in a Premier League youth soccer academy using the consensus statement: a prospective cohort study

PubMed Central

Renshaw, Andrew

2016-01-01

Background There is an established risk of injury to young athletes exposed to high training loads. Identifying and monitoring injury risk is essential to aid prevention. The aim of this study was to use the consensus statement to determine the incidence and pattern of injury in 1 English Premier League soccer academy during 1 season. Methods A prospective cohort study included 181 elite academy soccer players during the 2012–2013 season. Players were divided into 5 age groups between 9 and 18 years. The number, type and incidence of injuries were recorded during matches and training. Incidence was calculated per 1000 hours of exposure. Results 127 injuries occurred during 29 346 hours of soccer exposure. 72% of injuries were non-contact related. Under (U)18 players sustained the highest number of match injuries. U12–14 players sustained the highest number of training injuries and injuries overall. U16 players sustained the highest number of severe injuries, and U18 players sustained the highest number of moderate injuries. U18 players sustained the highest number of injuries/1000 hours of training and overall. U15 players sustained the highest number of injuries/1000 hours of matches, the highest number of recurrent injuries and the highest incidence of recurrence. The most common injuries were muscle injuries in U15 and U18 players. The most common injury location was the anterior thigh, with the majority of these occurring in training. Conclusions Using the consensus statement, this study used a repeatable method to identify the injury profile of elite academy-level soccer players. PMID:27900186

The expert advantage in dynamic pattern recall persists across both attended and unattended display elements.

PubMed

Gorman, Adam D; Abernethy, Bruce; Farrow, Damian

2013-07-01

We examined how differences in attention influence how expert and novice basketball players encode into memory the specific structural information contained within patterns of play from their sport. Our participants were primed during a typical recall task to focus attention on either attacking or defending player formations before being asked to recall the attended or unattended portion of the pattern. Adherence to the instructional set was confirmed through an analysis of gaze distributions. Recall performance was superior for the experts relative to the novices across both the attended and unattended attacking and defensive pattern structures. Expert recall of attacker positions was unchanged with and without attention, whereas recall accuracy for the positions of defenders diminished without attention, as did the novices' recall of both attack and defense formations. The findings suggest that experienced performers are better than novices at encoding the elements from a complex and dynamic pattern in the absence of focused attention, with this advantage being especially evident in relation to the recall of attacking structure. Some revision of long-term memory theories of expertise will be necessary to accommodate these findings.

What Performance Analysts Need to Know About Research Trends in Association Football (2012-2016): A Systematic Review.

PubMed

Sarmento, Hugo; Clemente, Filipe Manuel; Araújo, Duarte; Davids, Keith; McRobert, Allistair; Figueiredo, António

2018-04-01

Evolving patterns of match analysis research need to be systematically reviewed regularly since this area of work is burgeoning rapidly and studies can offer new insights to performance analysts if theoretically and coherently organized. The purpose of this paper was to conduct a systematic review of published articles on match analysis in adult male football, identify and organize common research topics, and synthesize the emerging patterns of work between 2012 and 2016, according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. The Web of Science database was searched for relevant published studies using the following keywords: 'football' and 'soccer', each one associated with the terms 'match analysis', 'performance analysis', 'notational analysis', 'game analysis', 'tactical analysis' and 'patterns of play'. Of 483 studies initially identified, 77 were fully reviewed and their outcome measures extracted and analyzed. Results showed that research mainly focused on (1) performance at set pieces, i.e. corner kicks, free kicks, penalty kicks; (2) collective system behaviours, captured by established variables such as team centroid (geometrical centre of a set of players) and team dispersion (quantification of how far players are apart), as well as tendencies for team communication (establishing networks based on passing sequences), sequential patterns (predicting future passing sequences), and group outcomes (relationships between match-related statistics and final match scores); and (3) activity profile of players, i.e. playing roles, effects of fatigue, substitutions during matches, and the effects of environmental constraints on performance, such as heat and altitude. From the previous review, novel variables were identified that require new measurement techniques. It is evident that the complexity engendered during performance in competitive soccer requires an integrated approach that considers multiple aspects. A challenge for researchers is to align these new measures with the needs of the coaches through a more integrated relationship between coaches and researchers, to produce practical and usable information that improves player performance and coach activity.

Action Video Games Improve Direction Discrimination of Parafoveal Translational Global Motion but Not Reaction Times.

PubMed

Pavan, Andrea; Boyce, Matthew; Ghin, Filippo

2016-10-01

Playing action video games enhances visual motion perception. However, there is psychophysical evidence that action video games do not improve motion sensitivity for translational global moving patterns presented in fovea. This study investigates global motion perception in action video game players and compares their performance to that of non-action video game players and non-video game players. Stimuli were random dot kinematograms presented in the parafovea. Observers discriminated the motion direction of a target random dot kinematogram presented in one of the four visual quadrants. Action video game players showed lower motion coherence thresholds than the other groups. However, when the task was performed at threshold, we did not find differences between groups in terms of distributions of reaction times. These results suggest that action video games improve visual motion sensitivity in the near periphery of the visual field, rather than speed response. © The Author(s) 2016.

Habituation of 10-year-old hockey players to treadmill skating.

PubMed

Lockwood, Kelly L; Frost, Gail

2007-05-01

This study assessed changes in selected physiological and kinematic variables over 6 weeks of treadmill skating in an effort to understand the process of habituation to this novel training modality. Seven male, Atom-A hockey players who were injury-free and had no previous treadmill skating experience participated in the study. Players performed four 1-min skating bouts at progressively increasing speeds, each week, for 6 weeks. One speed (10.5 km/h) was repeated weekly to allow for assessment of the habituation process. Our criteria for habituation were: a decrease in stride rate, heart rate and rating of perceived exertion, and an increase in stride length, trunk angle and vertical movement of the centre of mass, leading to a plateau, over the course of the 6-week study. Significant decreases were seen in stride rate, heart rate and ratings of perceived exertion, and significant increases were found in stride length. Some of these changes were evident after only one week of training and all were present by week 4. After 6 weeks (24 min) of exposure to treadmill skating, all participants displayed a visibly more efficient skating style.

Multiple player tracking in sports video: a dual-mode two-way bayesian inference approach with progressive observation modeling.

PubMed

Xing, Junliang; Ai, Haizhou; Liu, Liwei; Lao, Shihong

2011-06-01

Multiple object tracking (MOT) is a very challenging task yet of fundamental importance for many practical applications. In this paper, we focus on the problem of tracking multiple players in sports video which is even more difficult due to the abrupt movements of players and their complex interactions. To handle the difficulties in this problem, we present a new MOT algorithm which contributes both in the observation modeling level and in the tracking strategy level. For the observation modeling, we develop a progressive observation modeling process that is able to provide strong tracking observations and greatly facilitate the tracking task. For the tracking strategy, we propose a dual-mode two-way Bayesian inference approach which dynamically switches between an offline general model and an online dedicated model to deal with single isolated object tracking and multiple occluded object tracking integrally by forward filtering and backward smoothing. Extensive experiments on different kinds of sports videos, including football, basketball, as well as hockey, demonstrate the effectiveness and efficiency of the proposed method.

Performance nutrition guidelines for international rugby sevens tournaments.

PubMed

Dziedzic, Christine E; Higham, Dean G

2014-06-01

Rugby sevens is an abbreviated version of rugby union, played by teams of seven players over 7-min halves. International competitions are usually played in a tournament format. While shorter in duration, the movement demands of rugby sevens per min of match time are greater than rugby union, resulting in an accentuated load on players. This load can be repeated up to six times over a typical 2- or 3-day competition period. The potential cumulative effect of inadequate carbohydrate, protein and/or fluid intake over the course of a tournament is the greatest nutrition-related concern for players. Nutritional strategies before and during competition are suggested to replenish substrate stores, maintain fluid balance and promote recovery between matches. The use of ergogenic aids known to enhance intermittent, high-intensity activity and/or the execution of motor skills may be advantageous to rugby sevens performance and is discussed. This review provides a best-practice model of nutritional support for international rugby sevens competition based on our current understanding of the sport combined with pragmatic guidelines and considerations for the practitioner.

ARC-2010-AD10-0106-015

NASA Image and Video Library

2010-06-07

Stephen Beitashour, a professional soccer player from the San Jose Earthquakes, was asked to demonstrate kicking the ball for his student audience. With the increased globalization of soccer, more young people are playing the sport and developing motor skills to compete effectively. To enhance their skills, students in the United States and Canada recently were given the opportunity to discuss with a NASA scientist the aerodynamics of the newly designed soccer ball. To help student soccer players better understand the movement of the ball, NASA scientists at the Fluid Mechanics Laboratory at NASA’s Ames Research Center, Moffett Field, Calif., recently tested the performance of the Jabulani design, and compared it to the 2006 design. Included in this study was Rabi Mehta who had done previous tests on tennis and cricket balls in wind tunnels.

The effect of biological movement variability on the performance of the golf swing in high- and low-handicapped players.

PubMed

Bradshaw, Elizabeth J; Keogh, Justin W L; Hume, Patria A; Maulder, Peter S; Nortje, Jacques; Marnewick, Michel

2009-06-01

The purpose of this study was to examine the role of neuromotor noise on golf swing performance in high- and low-handicap players. Selected two-dimensional kinematic measures of 20 male golfers (n=10 per high- or low-handicap group) performing 10 golf swings with a 5-iron club was obtained through video analysis. Neuromotor noise was calculated by deducting the standard error of the measurement from the coefficient of variation obtained from intra-individual analysis. Statistical methods included linear regression analysis and one-way analysis of variance using SPSS. Absolute invariance in the key technical positions (e.g., at the top of the backswing) of the golf swing appears to be a more favorable technique for skilled performance.

Ulnar nerve entrapment in a French horn player.

PubMed

Hoppmann, R A

1997-10-01

Nerve entrapment syndromes are frequent among musicians. Because of the demands on the musculoskeletal system and the great agility needed to per-form, musicians often present with vague complaints early in the course of entrapment, which makes the diagnosis a challenge for the clinician. Presented here is such a case of ulnar nerve entrapment at the left elbow of a French horn player. This case points out some of the difficulties in establishing a diagnosis of nerve entrapment in musicians. It also supports the theory that prolonged elbow flexion and repetitive finger movement contribute to the development of ulnar entrapment at the elbow. Although surgery is not required for most of the musculoskeletal problems of musicians, release of an entrapped nerve refractory to conservative therapy may be career-saving for the musician.

The Efficacy of Exergames Played Proximally and over the Internet on Cognitive Functioning for Online Physical Education

ERIC Educational Resources Information Center

Kooiman, Brian J.; Sheehan, Dwayne P.

2014-01-01

Exergames (active video games that require kinesthetic movement) played in proximity to other players or against a gaming machine have been linked to positive increases in cognitive functioning. This study tested to see if remote exergame play over the Internet had an impact similar to exergames that are played in proximity. The study shows that…

Grassroots Activists and the Three Branches of Government: "Key Players in the Civil Rights Movement"

ERIC Educational Resources Information Center

Brown, Elizabeth; Silvestri, Linda

2014-01-01

In order to understand the complex workings of the three branches of American government, young citizens need early exposure in the elementary years to hands-on lessons that include real life examples and opportunities for students to apply what they have learned. To that end, the authors designed a five-day, inquiry-based unit for fourth grade…

Futsal World Cup: Differences Created by Winning, Losing and Drawing Variables in Scored Goals and Offensive Variations

ERIC Educational Resources Information Center

Balyan, Melih; Vural, Faik

2018-01-01

Futsal, which can be defined as a new sports branch compared to football, has some shortcomings in comparison with football as well according to the studies carried out. Studies have rather focused on the movement characteristics of futsal players during the game and the physiological effects of games. On the other hand, there are only a limited…

Effects of prophylactic knee bracing on knee joint kinetics and kinematics during netball specific movements.

PubMed

Sinclair, Jonathan K; Vincent, Hayley; Richards, Jim D

2017-01-01

To investigate the effects of a prophylactic knee brace on knee joint kinetics and kinematics during netball specific movements. Repeated measures. Laboratory. Twenty university first team level female netball players. Participants performed three movements, run, cut and vertical jump under two conditions (brace and no-brace). 3-D knee joint kinetics and kinematics were measured using an eight-camera motion analysis system. Knee joint kinetics and kinematics were examined using 2 × 3 repeated measures ANOVA whilst the subjective ratings of comfort and stability were investigated using chi-squared tests. The results showed no differences (p > 0.05) in knee joint kinetics. However the internal/external rotation range of motion was significantly (p < 0.05) reduced when wearing the brace in all movements. The subjective ratings of stability revealed that netballers felt that the knee brace improved knee stability in all movements. Further study is required to determine whether reductions in transverse plane knee range of motion serve to attenuate the risk from injury in netballers. Copyright © 2016 Elsevier Ltd. All rights reserved.

There Is Time for Calculation in Speed Chess, and Calculation Accuracy Increases With Expertise.

PubMed

Chang, Yu-Hsuan A; Lane, David M

2016-01-01

The recognition-action theory of chess skill holds that expertise in chess is due primarily to the ability to recognize familiar patterns of pieces. Despite its widespread acclaim, empirical evidence for this theory is indirect. One source of indirect evidence is that there is a high correlation between speed chess and standard chess. Assuming that there is little or no time for calculation in speed chess, this high correlation implies that calculation is not the primary factor in standard chess. Two studies were conducted analyzing 100 games of speed chess. In Study 1, we examined the distributions of move times, and the key finding was that players often spent considerable time on a few moves. Moreover, stronger players were more likely than weaker players to do so. Study 2 examined skill differences in calculation by examining poor moves. The stronger players made proportionally fewer blunders (moves that a 2-ply search would have revealed to be errors). Overall, the poor moves made by the weaker players would have required a less extensive search to be revealed as poor moves than the poor moves made by the stronger players. Apparently, the stronger players are searching deeper and more accurately. These results are difficult to reconcile with the view that speed chess does not allow players time to calculate extensively and call into question the assertion that the high correlation between speed chess and standard chess supports recognition-action theory.

Physical and Physiological Demands of Experienced Male Basketball Players During a Competitive Game.

PubMed

Puente, Carlos; Abián-Vicén, Javier; Areces, Francisco; López, Roberto; Del Coso, Juan

2017-04-01

Puente, C, Abián-Vicén, J, Areces, F, López, R, and Del Coso, J. Physical and physiological demands of experienced male basketball players during a competitive game. J Strength Cond Res 31(4): 956-962, 2017-The aim of this investigation was to analyze the physical and physiological demands of experienced basketball players during a real and competitive game. Twenty-five well-trained basketball players (8 guards, 8 forwards, and 9 centers) played a competitive game on an outdoor court. Instantaneous running speeds, the number of body impacts above 5 g, and the number of accelerations and decelerations were assessed by means of a 15-Hz global Positioning System accelerometer unit. Individual heart rate was also recorded using heart rate monitors. As a group mean, the basketball players covered 82.6 ± 7.8 m·min during the game with a mean heart rate of 89.8 ± 4.4% of maximal heart rate. Players covered 3 ± 3% of the total distance running at above 18 km·h and performed 0.17 ± 0.13 sprints per minute. The number of body impacts was 8.2 ± 1.8 per minute of play. The running pace of forwards was higher than that of centers (86.8 ± 6.2 vs. 76.6 ± 6.0 m·min; p ≤ 0.05). The maximal speed obtained during the game was significantly higher for guards than that for centers (24.0 ± 1.6 km·h vs. 21.3 ± 1.6 km·h; p ≤ 0.05). Centers performed a lower number of accelerations/decelerations than guards and forwards (p ≤ 0.05). In conclusion, the extraordinary rates of specific movements performed by these experienced basketball players indicate the high physiological demands necessary to be able to compete in this sport. The centers were the basketball players who showed lower physiological demands during a game, whereas there were no differences between guards and forwards. These results can be used by coaches to adapt basketball training programs to the specific demands of each playing position.

Eye Movements during Silent and Oral Reading in a Regular Orthography: Basic Characteristics and Correlations with Childhood Cognitive Abilities and Adolescent Reading Skills

PubMed Central

Krieber, Magdalena; Bartl-Pokorny, Katrin D.; Pokorny, Florian B.; Zhang, Dajie; Landerl, Karin; Körner, Christof; Pernkopf, Franz; Pock, Thomas; Einspieler, Christa; Marschik, Peter B.

2017-01-01

The present study aimed to define differences between silent and oral reading with respect to spatial and temporal eye movement parameters. Eye movements of 22 German-speaking adolescents (14 females; mean age = 13;6 years;months) were recorded while reading an age-appropriate text silently and orally. Preschool cognitive abilities were assessed at the participants’ age of 5;7 (years;months) using the Kaufman Assessment Battery for Children. The participants’ reading speed and reading comprehension at the age of 13;6 (years;months) were determined using a standardized inventory to evaluate silent reading skills in German readers (Lesegeschwindigkeits- und -verständnistest für Klassen 6–12). The results show that (i) reading mode significantly influenced both spatial and temporal characteristics of eye movement patterns; (ii) articulation decreased the consistency of intraindividual reading performances with regard to a significant number of eye movement parameters; (iii) reading skills predicted the majority of eye movement parameters during silent reading, but influenced only a restricted number of eye movement parameters when reading orally; (iv) differences with respect to a subset of eye movement parameters increased with reading skills; (v) an overall preschool cognitive performance score predicted reading skills at the age of 13;6 (years;months), but not eye movement patterns during either silent or oral reading. However, we found a few significant correlations between preschool performances on subscales of sequential and simultaneous processing and eye movement parameters for both reading modes. Overall, the findings suggest that eye movement patterns depend on the reading mode. Preschool cognitive abilities were more closely related to eye movement patterns of oral than silent reading, while reading skills predicted eye movement patterns during silent reading, but less so during oral reading. PMID:28151950

Feeding & Motor Functioning: Start at the Hips to Get to the Lips

ERIC Educational Resources Information Center

Donato, Jessica; Fox, Cathy; Mormon, Johnnie; Mormon, Mike

2008-01-01

Swallowing is one of the most complex movement patterns that people must use accurately throughout the day and night from the time they are born. These movement patterns are very closely integrated with breathing and movement of food through the aerodigestive tract. Malalignment or dysfunction in any part of these integrated patterns and systems…

Patterns of Movement in Foster Care: An Optimal Matching Analysis

PubMed Central

Havlicek, Judy

2011-01-01

Placement instability remains a vexing problem for child welfare agencies across the country. This study uses child welfare administrative data to retrospectively follow the entire placement histories (birth to age 17.5) of 474 foster youth who reached the age of majority in the state of Illinois and to search for patterns in their movement through the child welfare system. Patterns are identified through optimal matching and hierarchical cluster analyses. Multiple logistic regression is used to analyze administrative and survey data in order to examine covariates related to patterns. Five distinct patterns of movement are differentiated: Late Movers, Settled with Kin, Community Care, Institutionalized, and Early Entry. These patterns suggest high but variable rates of movement. Implications for child welfare policy and service provision are discussed. PMID:20873020

Effects of heavy episodic drinking on physical performance in club level rugby union players.

PubMed

Prentice, Christopher; Stannard, Stephen R; Barnes, Matthew J

2015-05-01

This study investigated the effects of acute alcohol consumption, in a natural setting, on exercise performance in the 2 days after the drinking episode. Additionally, alcohol related behaviours of this group of rugby players were identified. Prospective cohort study. Nineteen male club rugby players volunteered for this study. Measures of counter movement jump, maximal lower body strength, repeated sprint ability and hydration were made 2 days before and in the 2 days following heavy episodic alcohol consumption. Participants completed a questionnaire at each time point so that alcohol consumption and sleep hours from the previous 24 h period could be quantified. Additionally, participants completed the Alcohol Use Disorders Test (AUDIT) prior to completing baseline measures of performance. Reported alcohol consumption ranged from 6 to >20 standard drinks (mean category scale score=11-19 standard drinks). A significant decrease in sleep hours (p=0.01) was reported after the drinking episode with participants reporting 1-3 h for the night. A significant reduction (-1.8±1.5 cm) in counter movement jump (p<0.01) the morning after the drinking episode was observed; no other measures were altered at any time point compared to baseline (p>0.05). AUDIT scores for this group (18.2±4.3) indicate regular alcohol consumption at a hazardous level. Heavy episodic alcohol use, and associated reduced sleep hours, results in a reduction in lower body power output but not other measures of anaerobic performance the morning after a drinking session. Full recovery from this behaviour is achieved by 2 days post drinking episode. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Combined individual scrummaging kinetics and muscular power predict competitive team scrum success.

PubMed

Green, Andrew; Dafkin, Chloe; Kerr, Samantha; McKinon, Warrick

2017-09-01

Scrummaging is a major component of Rugby Union gameplay. Successful scrummaging is dependent on the coordination of the forward players and the strength of the eight individuals. The study aim was to determine whether individual scrummaging kinetics and other candidate factors associated with scrummaging performance discriminate team scrum performances. Sixteen club-level forwards (stature: 1.80 ± 0.1 m; mass: 99.0 ± 18.2 kg) were initially divided into two scrummaging packs. A total of 10 various scrum permutations were tested, where players were randomly swapped between the two packs. Winning scrums were determined by two observers on opposite sides of the scrum. Fatigue (100 mm visual analogue scale (VAS)) and scrummaging effort (6-20 rating of perceived exertion (RPE)) were assessed following each scrum contest. Individual scrummaging kinetics were acquired through an instrumented scrum ergometer and muscular power indicated through vertical jump heights. Student's t-tests were used to differentiate between winning and losing scrum packs. VAS and RPE were assessed using repeated measures ANOVAs. Winning scrum packs had significantly larger combined force magnitudes (p < .002), regardless of the player contribution calculations. Additionally, winning packs had less individual movement (p = .033) and higher combined vertical jump heights (p < .001) but were not significantly heavier (p = .759) than losing scrum packs. While perceived VAS and RPE values progressively increased (p < .001), no differences in the individual scrum magnitudes were observed between the 1st and 10th scrum (p = .418). The results indicated that the combination of individual forces, variation in movement and factors related to scrummaging performance, such as vertical jump height, were associated with team scrummaging success.

Strategy of arm movement control is determined by minimization of neural effort for joint coordination.

PubMed

Dounskaia, Natalia; Shimansky, Yury

2016-06-01

Optimality criteria underlying organization of arm movements are often validated by testing their ability to adequately predict hand trajectories. However, kinematic redundancy of the arm allows production of the same hand trajectory through different joint coordination patterns. We therefore consider movement optimality at the level of joint coordination patterns. A review of studies of multi-joint movement control suggests that a 'trailing' pattern of joint control is consistently observed during which a single ('leading') joint is rotated actively and interaction torque produced by this joint is the primary contributor to the motion of the other ('trailing') joints. A tendency to use the trailing pattern whenever the kinematic redundancy is sufficient and increased utilization of this pattern during skillful movements suggests optimality of the trailing pattern. The goal of this study is to determine the cost function minimization of which predicts the trailing pattern. We show that extensive experimental testing of many known cost functions cannot successfully explain optimality of the trailing pattern. We therefore propose a novel cost function that represents neural effort for joint coordination. That effort is quantified as the cost of neural information processing required for joint coordination. We show that a tendency to reduce this 'neurocomputational' cost predicts the trailing pattern and that the theoretically developed predictions fully agree with the experimental findings on control of multi-joint movements. Implications for future research of the suggested interpretation of the trailing joint control pattern and the theory of joint coordination underlying it are discussed.

Movement patterns of Tenebrio beetles demonstrate empirically that correlated-random-walks have similitude with a Lévy walk.

PubMed

Reynolds, Andy M; Leprêtre, Lisa; Bohan, David A

2013-11-07

Correlated random walks are the dominant conceptual framework for modelling and interpreting organism movement patterns. Recent years have witnessed a stream of high profile publications reporting that many organisms perform Lévy walks; movement patterns that seemingly stand apart from the correlated random walk paradigm because they are discrete and scale-free rather than continuous and scale-finite. Our new study of the movement patterns of Tenebrio molitor beetles in unchanging, featureless arenas provides the first empirical support for a remarkable and deep theoretical synthesis that unites correlated random walks and Lévy walks. It demonstrates that the two models are complementary rather than competing descriptions of movement pattern data and shows that correlated random walks are a part of the Lévy walk family. It follows from this that vast numbers of Lévy walkers could be hiding in plain sight.

The role of insect dispersal and migration in population processes

NASA Technical Reports Server (NTRS)

Rabb, R. L.; Stinner, R. E.

1979-01-01

Movement functions in the population dynamics of insects are discussed. Modes of movement, movement from a population view, and population patterns are described and predicted. A wide-area of spatial and temporal patterns are presented.

An equilibrium-point model for fast, single-joint movement: I. Emergence of strategy-dependent EMG patterns.

PubMed

Latash, M L; Gottlieb, G L

1991-09-01

We describe a model for the regulation of fast, single-joint movements, based on the equilibrium-point hypothesis. Limb movement follows constant rate shifts of independently regulated neuromuscular variables. The independently regulated variables are tentatively identified as thresholds of a length sensitive reflex for each of the participating muscles. We use the model to predict EMG patterns associated with changes in the conditions of movement execution, specifically, changes in movement times, velocities, amplitudes, and moments of limb inertia. The approach provides a theoretical neural framework for the dual-strategy hypothesis, which considers certain movements to be results of one of two basic, speed-sensitive or speed-insensitive strategies. This model is advanced as an alternative to pattern-imposing models based on explicit regulation of timing and amplitudes of signals that are explicitly manifest in the EMG patterns.

Knee injuries in women collegiate rugby players.

PubMed

Levy, A S; Wetzler, M J; Lewars, M; Laughlin, W

1997-01-01

We evaluated the prevalence and patterns of knee injuries in 810 women collegiate rugby players. Injuries that resulted in players missing at least one game were recorded and a questionnaire was used to delineate players' rugby and knee injury history. There were 76 total knee injuries in 58,296 exposures. This resulted in a 1.3 knee injury rate per 1000 exposures. Twenty-one anterior cruciate ligament tears were reported for a 0.36 incidence per 1000 exposures. Other injuries included meniscal tears (25), medical collateral ligament sprains (23), patellar dislocations (5), and posterior cruciate ligament tears (2). Sixty-one percent of the medial collateral ligament sprains occurred in rugby forwards and 67% of anterior cruciate ligament tears occurred in rugby backs. All other injuries occurred with equal frequency in backs and forwards. This study demonstrates that knee injury rates in women's collegiate rugby are similar to those reported for other women's collegiate sports. The overall rate of anterior cruciate ligament injury in women's rugby, however, is slightly higher than that reported for women soccer and basketball players.

Incidence and Nature of Medical Attendance Injuries in English Community Rugby Union

PubMed Central

Roberts, Simon P.; Trewartha, Grant; England, Mike; Stokes, Keith A.

2014-01-01

Background: Previous research has identified injury patterns during community-level rugby union match play, but none have investigated the frequency and reasons for on-field injury management. Purpose: To establish the frequency, reasons, and patterns of on-field injury management in English community rugby, including differences between different levels of play. Study Design: Descriptive epidemiology study. Methods: Over 3 seasons, injury information was collected from 46 (2009-2010), 67 (2010-2011), and 76 (2011-2012) English community clubs (Rugby Football Union [RFU] levels 3-9). Club injury management staff reported information for all medical attendances during match play, including details on the injury site and type, playing position (seasons 2010-2011 and 2011-2012 only), and whether the player was removed from play. Clubs were subdivided into groups A (RFU levels 3 and 4 [mainly semiprofessional]; n = 39), B (RFU levels 5 and 6 [mainly amateur]; n = 71), and C (RFU levels 7-9 [social and recreational]; n = 79) to differentiate playing levels. Results: The overall medical attendance incidence was 229 per 1000 player-match hours (95% CI, 226-232), with 45 players removed per 1000 player-match hours (95% CI, 44-46). Attendance incidence for group A (294 per 1000 player-match hours; 95% CI, 287-301) was higher compared with group B (213; 95% CI, 208-218; P < .001) and C (204; 95% CI, 200-209; P < .001). There was a higher incidence of attendances to forwards (254; 95% CI, 249-259) compared with backs (191; 95% CI, 187-196; P < .001). The head was the most common specific site of injury (55 per 1000 player-match hours; 95% CI, 53-57) but the lower limb region overall accounted for most attendances (87; 95% CI, 85-89) and the greatest chance of removal from the pitch (22; 95% CI, 21-23). Conclusion: With the likelihood of 1 injury for each team per match severe enough for the player to leave the pitch and with at least 1 attendance for a head injury per match, there is clear evidence that pitch side staff should be trained to recognize potentially serious injuries. PMID:26535294

The Effect of Core Stability Training on Functional Movement Patterns in Collegiate Athletes.

PubMed

Bagherian, Sajad; Ghasempoor, Khodayar; Rahnama, Nader; Wikstrom, Erik A

2018-02-06

Pre-participation examinations are the standard approach for assessing poor movement quality that would increase musculoskeletal injury risk. However, little is known about how core stability influences functional movement patterns. The primary purpose of this study was to determine the effect of an 8-week core stability program on functional movement patterns in collegiate athletes. The secondary purpose was to determine if the core stability training program would be more effective in those with worse movement quality (i.e. ≤14 baseline FMS score). Quasi-experimental design. Athletic Training Facility. One-hundred collegiate athletes. Functional movement patterns included the Functional Movement Screen (FMS), Lateral step down (LSD) and Y balance test (YBT) and were assessed before and after the 8-week program. Participants were placed into 1 of the 2 groups: intervention and control. The intervention group was required to complete a core stability training program that met 3 times per week for 8-week. Significant group x time interactions demonstrated improvements in FMS, LSD and YBT scores in the experimental group relative to the control group (p<0.001). Independent sample t-tests demonstrate that change scores were larger (greater improvement) for the FMS total score and Hurdle step (p<0.001) in athletes with worse movement quality. An 8-week core stability training program enhances functional movement patterns and dynamic postural control in collegiate athletes. The benefits are more pronounced in collegiate athletes with poor movement quality.

Shoe drop reduction influences the lower limb biomechanics of children tennis players during an open stance forehand: A longitudinal study.

PubMed

Herbaut, Alexis; Simoneau-Buessinger, Emilie; Barbier, Franck; Gillet, Christophe; Roux, Maxime; Guéguen, Nils; Chavet, Pascale

2017-11-01

Compared to traditional tennis shoes, using 0-drop shoes was shown to induce an immediate switch from rear- to forefoot strike pattern to perform an open stance tennis forehand for 30% of children tennis players. The purpose of the study was to examine the long-term effects of a gradual reduction in the shoe drop on the biomechanics of children tennis players performing open stance forehands. Thirty children tennis players participated in 2 laboratory biomechanical test sessions (intermediate: +4 months and final: +8 months) after an inclusion visit where they were randomly assigned to control (CON) or experimental (EXP) group. CON received 12-mm-drop shoes twice, whereas EXP received 8 mm then 4-mm-drop shoes. Strike index indicated that all CON were rearfoot strikers in intermediate and final test sessions. All EXP were rearfoot strikers in intermediate test session, but half the group switched towards a forefoot strike pattern in final test session. This switch resulted in a decreased loading rate of the ground reaction force (-73%, p = .005) but increased peak ankle plantarflexors moment (+47%, p = .050) and peak ankle power absorption (+107%, p = .005) for these participants compared with CON. Biomechanical changes associated with the long-term use of partial minimalist shoes suggest a reduction in heel compressive forces but an increase in Achilles tendon tensile forces.

Evolutionary games and spatial chaos

NASA Astrophysics Data System (ADS)

Nowak, Martin A.; May, Robert M.

1992-10-01

MUCH attention has been given to the Prisoners' Dilemma as a metaphor for the problems surrounding the evolution of coopera-tive behaviour1-6. This work has dealt with the relative merits of various strategies (such as tit-for-tat) when players who recognize each other meet repeatedly, and more recently with ensembles of strategies and with the effects of occasional errors. Here we neglect all strategical niceties or memories of past encounters, considering only two simple kinds of players: those who always cooperate and those who always defect. We explore the consequences of placing these players in a two-dimensional spatial array: in each round, every individual 'plays the game' with the immediate neighbours; after this, each site is occupied either by its original owner or by one of the neighbours, depending on who scores the highest total in that round; and so to the next round of the game. This simple, and purely deterministic, spatial version of the Prisoners' Dilemma, with no memories among players and no strategical elaboration, can generate chaotically changing spatial patterns, in which cooperators and defectors both persist indefinitely (in fluctuating proportions about predictable long-term averages). If the starting configurations are sufficiently symmetrical, these ever-changing sequences of spatial patterns-dynamic fractals-can be extraordinarily beautiful, and have interesting mathematical properties. There are potential implications for the dynamics of a wide variety of spatially extended systems in physics and biology.

Coarse-scale movement patterns of a small-bodied fish inhabiting a desert stream

USGS Publications Warehouse

Dzul, M.C.; Quist, M.C.; Dinsmore, S.J.; Gaines, D.B.; Bower, M.R.

2013-01-01

Located on the floor of Death Valley (CA, USA), Salt Creek harbors a single fish species, the Salt Creek pupfish, Cyprinodon salinus salinus, which has adapted to this extremely harsh environment. Salt Creek is fed by an underground spring and is comprised of numerous pools, runs, and marshes that exhibit substantial variability in temperature, salinity, and dissolved oxygen concentrations. In addition, the wetted area of Salt Creek is reduced throughout the summer months due to high rates of evaporation, with some reaches drying completely. Therefore, it seems logical that short- and long-term movement patterns may play an important role in Salt Creek pupfish population dynamics. The objective of this study was to describe coarse-scale movements of Salt Creek pupfish in Salt Creek during their breeding season from March to May. Sex ratios and length–frequency distributions varied spatially within Salt Creek, suggesting population segregation during the breeding season. Long-distance movements were generally rare, although two fish moved more than 1.2 km. Movement in upstream reaches was rare or absent, in contrast to the greater movement observed in downstream reaches (29% of recaptures). Temporal trends and demographic patterns in movement were not observed. Because the two most downstream habitats dry up in the summer, our results indicate that coarse-scale movements that re-populate downstream reaches likely occur during other times of year. Consequently, the importance of small- and large-scale movements is influenced by season. Further assessment of Salt Creek movement patterns conducted during other times of year may better illuminate long-distance movement patterns and source-sink dynamics.

Effects of Environmental Context on Physiological Response During Team Handball Small Sided Games.

PubMed

Bělka, Jan; Hulka, Karel; Machová, Iva; Šafář, Michal; Weisser, Radim; Bellar, David M; Hoover, Donald L; Judge, Lawrence W

2017-01-01

This study examined the distance covered and physiological effects of altering the number of players during small-sided games (SSG) in team handball. Twelve professional female handball players [24.6±3.7 years, 172±6.2 cm, 68.2 ± 9.9kg, 22.7 ± 2 kg/m 2 ] participated in this study. The SSG were played, first with five on each side (SSG 5), then four (SSG 4), then three (SSG 3). Each game was four minutes long, followed by three minutes of rest. The distance covered and time spent in four speed zones (based on player movement speed) were selected for analysis: Zone 1 (0-1.4 m/s), Zone 2 (1.5-3.4 m/s), Zone 3 (3.5-5.2 m/s), and Zone 4 (>5.2 m/s). Statistically significant differences were found in Zone 2, between conditions SSG 3 and SSG 4 (p=.049,ω 2 = .32). The highest average heart rate (HR) occurred during SSG 3. Average HR between SSG 3 (89.7 % HRmax) and SSG 5 (87.8 % HRmax) (p= .04, ω2= .26) were also significantly different. Participant HR response between the speed zones was not statistically significant. HR response was negatively correlated with the number of players within the SSG condition. Statistically significant results were found for RPE between SSG 3 and the other two SSG conditions (SSG 4, p = .01, and SSG 5, p = .00). These results indicate that changing the number of SSG players can be used to manipulate the physiological response during handball training.

Effects of Environmental Context on Physiological Response During Team Handball Small Sided Games

PubMed Central

BĚLKA, JAN; HULKA, KAREL; MACHOVÁ, IVA; ŠAFÁŘ, MICHAL; WEISSER, RADIM; BELLAR, DAVID M.; HOOVER, DONALD L; JUDGE, LAWRENCE W.

2017-01-01

This study examined the distance covered and physiological effects of altering the number of players during small-sided games (SSG) in team handball. Twelve professional female handball players [24.6±3.7 years, 172±6.2 cm, 68.2 ± 9.9kg, 22.7 ± 2 kg/m2] participated in this study. The SSG were played, first with five on each side (SSG 5), then four (SSG 4), then three (SSG 3). Each game was four minutes long, followed by three minutes of rest. The distance covered and time spent in four speed zones (based on player movement speed) were selected for analysis: Zone 1 (0–1.4 m/s), Zone 2 (1.5–3.4 m/s), Zone 3 (3.5–5.2 m/s), and Zone 4 (>5.2 m/s). Statistically significant differences were found in Zone 2, between conditions SSG 3 and SSG 4 (p=.049,ω2= .32). The highest average heart rate (HR) occurred during SSG 3. Average HR between SSG 3 (89.7 % HRmax) and SSG 5 (87.8 % HRmax) (p= .04, ω2= .26) were also significantly different. Participant HR response between the speed zones was not statistically significant. HR response was negatively correlated with the number of players within the SSG condition. Statistically significant results were found for RPE between SSG 3 and the other two SSG conditions (SSG 4, p = .01, and SSG 5, p = .00). These results indicate that changing the number of SSG players can be used to manipulate the physiological response during handball training. PMID:29399252

The physical demands of Super 14 rugby union.

PubMed

Austin, Damien; Gabbett, Tim; Jenkins, David

2011-05-01

The purpose of the present study was to describe the match-play demands of professional rugby union players competing in Super 14 matches during the 2008 and 2009 seasons. The movements of 20 players from Super 14 rugby union team during the 2008 and 2009 seasons were video recorded. Using time-motion analysis (TMA), five players from four positional groups (front-row forwards, back-row forwards, inside backs and outside backs) were assessed. Players covered between 4218 m and 6389 m during the games. The maximum distances covered in a game by the four groups were: front row forwards (5139 m), back row forwards, (5422 m), inside backs (6389 m) and outside backs (5489 m). The back row forwards spent the greatest amount of time in high-intensity exercise (1190 s), followed by the front row forwards (1015 s), the inside backs (876 s) and the outside backs (570 s). Average distances covered in individual sprint efforts were: front row forwards (16 m), back row forwards (14 m), inside backs (17 m) and outside backs (18 m). Work to rest ratios of 1:4, 1:4, 1:5, and 1:6 were found for the front row and back row forwards, and inside and outside backs respectively. The Super 14 competition during 2008 and 2009, have resulted in an increase in total high-intensity activities, sprint frequency, and work to rest ratios across all playing positions. For players and teams to remain competitive in Super 14 rugby, training (including recovery practices) should reflect these current demands. Copyright © 2011 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Contemporary movements and tectonics on Canada's west coast: A discussion

NASA Astrophysics Data System (ADS)

Riddihough, Robin P.

1982-06-01

Evidence from published tidal records and geodetic relevelling data in British Columbia indicates that there is a consistent pattern of contemporary uplift on the outer coast (2 mm/yr) and subsidence on the inner coast (1-2 mm/yr). The zero uplift contour or "hinge-line" runs through Hecate Strait, Georgia Strait and Victoria. This pattern continues southwards into Washington State but is interrupted to the north by considerable uplift in southeastern Alaska. Although glacio-isostatic recovery has dominated vertical movements in the region over the last 10,000 years, the distribution and trend of the observed contemporary movements are not compatible with the pattern to be expected from this source and are most probably tectonic in origin. There is, however, no clear distinction between the movements seen opposite the Queen Charlotte transform margin and the Vancouver Island convergent margin. Comparison with movements observed at other active plate margins show that the pattern is essentially similar to that seen in association with subduction and convergence. The paradox that the vertical movement rates are much too great to explain observed geology and topography may be soluble by assuming that discontinuous lateral shifts of the movement pattern occur on a scale of hundreds of thousands of years.

Independent digit movements and precision grip patterns in 1-5-month-old human infants: hand-babbling, including vacuous then self-directed hand and digit movements, precedes targeted reaching.

PubMed

Wallace, Patricia S; Whishaw, Ian Q

2003-01-01

Previous work has described human reflexive grasp patterns in early infancy and visually guided reaching and grasping in late infancy. There has been no examination of hand movements in the intervening period. This was the purpose of the present study. We video recorded the spontaneous hand and digit movements made by alert infants over their first 5 months of age. Over this period, spontaneous hand and digit movements developed from fists to almost continuous, vacuous movements and then to self-directed grasping movements. Amongst the many hand and digit movements observed, four grasping patterns emerged during this period: fists, pre-precision grips associated with numerous digit postures, precision grips including the pincer grasp, and self-directed grasps. The finding that a wide range of independent digit movements and grasp patterns are displayed spontaneously by infants within their first 5 months of age is discussed in relation to the development of the motor system, including the suggestion that direct connections of the pyramidal tract are functional relatively early in infancy. It is also suggested that hand babbling, consisting of first vacuous and then self-directed movements, is preparatory to targeted reaching.

Suitability of FIFA's "The 11" Training Programme for Young Football Players - Impact on Physical Performance.

PubMed

Kilding, Andrew E; Tunstall, Helen; Kuzmic, Dejan

2008-01-01

There is a paucity of evidence regarding the use of injury prevention programmes for preadolescents participating in sport. "The 11 "injury prevention programme was developed by FIFA's medical research centre (F-MARC) to help reduce the risk of injury in football players aged 14 years and over. The aim of this study was to determine the suitability and effectiveness of "The 11 "for younger football players. Twenty-four [12 experimental (EXP), 12 control (CON)] young football players (age 10.4 ± 1.4 yr) participated. The EXP group followed "The 11 "training programme 5 days per week, for 6 weeks, completing all but one of the 10 exercises. Prior to, and after the intervention, both EXP and CON groups performed a battery of football-specific physical tests. Changes in performance scores within each group were compared using independent t-tests (p ≤ 0.05). Feedback was also gathered on the young players' perceptions of "The 11". No injuries occurred during the study in either group. Compliance to the intervention was 72%. Measures of leg power (3 step jump and counter-movement jump) increased significantly (3.4 and 6.0% respectively, p < 0.05). Speed over 20 m improved by 2% (p < 0.05). Most players considered "The 11 "beneficial but not enjoyable in the prescribed format. Given the observed improvements in the physical abilities and the perceived benefits of "The 11", it would appear that a modified version of the programme is appropriate and should be included in the training of young football players, for both physical development and potential injury prevention purposes, as well as to promote fair play. To further engage young football players in such a programme, some modification to "The 11 "should be considered. Key pointsChildren who participate in recreational and competitive sports, especially football, are susceptible to injury.There is a need for the design and assessment of injury prevention programmes for children.The 11 "improves essential physical performance characteristics and has the potential to reduce the risk of injury.It may be prudent to implement a 'child-friendly' version of "The 11", to enhance long-term programme adherence and to ensure progressive physical development of players.

Prospective Player-Reported Injuries in Female Youth Fast-Pitch Softball Players.

PubMed

Smith, Matthew V; Davis, Randi; Brophy, Robert H; Prather, Heidi; Garbutt, Jane; Wright, Rick W

2015-01-01

There is a scarcity of literature evaluating injuries in youth fast-pitch softball players. To perform a descriptive analysis of player-reported injuries in youth fast-pitch softball position players and pitchers during a single select-level season. Prospective observation cohort study. Level 3. Ninety-eight athletes (48 pitchers, 50 position players) were followed for a single select fast-pitch softball season. Study participants completed web-based surveys every 3 weeks reporting injuries related to participation in fast-pitch softball. Injury was defined as pain causing cessation of participation in the current game or practice that prevents the player's return to that session or any pain that causes cessation of a player's customary participation on the day after the day of onset. The median age of the study participants was 14 years (range, 9-18 years). There were 49 reported injuries in 98 athletes. The average age was 13 years for those not injured and 14 years for those who were injured (P < 0.02). There were 31 injuries that were not related to pitching: 19 occurred in position players and 12 occurred in pitchers; 70% of these injuries were to the lower extremity. The proportion of injuries not related to pitching was significantly greater than the proportion of injuries related to pitching (P < 0.02). Eighteen injuries among the 48 pitchers (38%) were directly attributed to pitching. Among the 18 pitching injuries, 11 (61%) involved the shoulder. The majority (78%) of injuries related to pitching occurred in the first 6 weeks of the season. There was a high incidence of injury in this prospective cohort of youth select-level fast-pitch softball players. Better off-season and preseason conditioning may be a key factor for reducing pitching injuries. Recognition of injury patterns in fast-pitch softball players is critical to developing strategies to keep these athletes competing safely. © 2015 The Author(s).

Computer mouse movement patterns: A potential marker of mild cognitive impairment.

PubMed

Seelye, Adriana; Hagler, Stuart; Mattek, Nora; Howieson, Diane B; Wild, Katherine; Dodge, Hiroko H; Kaye, Jeffrey A

2015-12-01

Subtle changes in cognitively demanding activities occur in MCI but are difficult to assess with conventional methods. In an exploratory study, we examined whether patterns of computer mouse movements obtained from routine home computer use discriminated between older adults with and without MCI. Participants were 42 cognitively intact and 20 older adults with MCI enrolled in a longitudinal study of in-home monitoring technologies. Mouse pointer movement variables were computed during one week of routine home computer use using algorithms that identified and characterized mouse movements within each computer use session. MCI was associated with making significantly fewer total mouse moves ( p <.01), and making mouse movements that were more variable, less efficient, and with longer pauses between movements ( p <.05). Mouse movement measures were significantly associated with several cognitive domains ( p 's<.01-.05). Remotely monitored computer mouse movement patterns are a potential early marker of real-world cognitive changes in MCI.

Altered movement patterns and muscular activity during single and double leg squats in individuals with anterior cruciate ligament injury.

PubMed

Trulsson, Anna; Miller, Michael; Hansson, Gert-Åke; Gummesson, Christina; Garwicz, Martin

2015-02-13

Individuals with Anterior Cruciate Ligament (ACL) injury often show altered movement patterns, suggested to be partly due to impaired sensorimotor control. Here, we therefore aimed to assess muscular activity during movements often used in ACL-rehabilitation and to characterize associations between deviations in muscular activity and specific altered movement patterns, using and further exploring the previously developed Test for substitution Patterns (TSP). Sixteen participants (10 women) with unilateral ACL rupture performed Single and Double Leg Squats (SLS; DLS). Altered movement patterns were scored according to TSP, and Surface Electromyography (SEMG) was recorded bilaterally in six hip, thigh and shank muscles. To quantify deviations in muscular activity, SEMG ratios were calculated between homonymous muscles on injured and non-injured sides, and between antagonistic muscles on the same side. Correlations between deviations of injured/non-injured side SEMG ratios and specific altered movement patterns were calculated. Injured/non-injured ratios were low at transition from knee flexion to extension in quadriceps in SLS, and in quadriceps and hamstrings in DLS. On injured side, the quadriceps/hamstrings ratio prior to the beginning of DLS and end of DLS and SLS, and tibialis/gastrocnemius ratio at end of DLS were lower than on non-injured side. Correlations were found between specific altered movement patterns and deviating muscular activity at transition from knee flexion to extension in SLS, indicating that the more deviating the muscular activity on injured side, the more pronounced the altered movement pattern. "Knee medial to supporting foot" correlated to lower injured/non-injured ratios in gluteus medius (rs = -0.73, p = 0.001), "lateral displacement of hip-pelvis-region" to lower injured/non-injured ratios in quadriceps (rs = -0.54, p = 0.03) and "displacement of trunk" to higher injured/non-injured ratios in gluteus medius (rs = 0.62, p = 0.01). Deviations in muscular activity between injured and non-injured sides and between antagonistic muscular activity within injured as compared to non-injured sides indicated specific alterations in sensorimotor control of the lower limb in individuals with ACL rupture. Also, correlations between deviating muscular activity and specific altered movement patterns were suggested as indications of altered sensorimotor control. We therefore advocate that quantitative assessments of altered movement patterns should be considered in ACL-rehabilitation.

Phase separation driven by density-dependent movement: A novel mechanism for ecological patterns.

PubMed

Liu, Quan-Xing; Rietkerk, Max; Herman, Peter M J; Piersma, Theunis; Fryxell, John M; van de Koppel, Johan

2016-12-01

Many ecosystems develop strikingly regular spatial patterns because of small-scale interactions between organisms, a process generally referred to as spatial self-organization. Self-organized spatial patterns are important determinants of the functioning of ecosystems, promoting the growth and survival of the involved organisms, and affecting the capacity of the organisms to cope with changing environmental conditions. The predominant explanation for self-organized pattern formation is spatial heterogeneity in establishment, growth and mortality, resulting from the self-organization processes. A number of recent studies, however, have revealed that movement of organisms can be an important driving process creating extensive spatial patterning in many ecosystems. Here, we review studies that detail movement-based pattern formation in contrasting ecological settings. Our review highlights that a common principle, where movement of organisms is density-dependent, explains observed spatial regular patterns in all of these studies. This principle, well known to physics as the Cahn-Hilliard principle of phase separation, has so-far remained unrecognized as a general mechanism for self-organized complexity in ecology. Using the examples presented in this paper, we explain how this movement principle can be discerned in ecological settings, and clarify how to test this mechanism experimentally. Our study highlights that animal movement, both in isolation and in unison with other processes, is an important mechanism for regular pattern formation in ecosystems. Copyright © 2016 Elsevier B.V. All rights reserved.

Differences in Neuromuscular Strategies Between Landing and Cutting Tasks in Female Basketball and Soccer Athletes

PubMed Central

Cowley, Hanni R; Ford, Kevin R; Myer, Gregory D; Kernozek, Thomas W; Hewett, Timothy E

2006-01-01

Context: High school female athletes are most likely to sustain a serious knee injury during soccer or basketball, 2 sports that often involve a rapid deceleration before a change of direction or while landing from a jump. Objective: To determine if female high school basketball and soccer players show neuromuscular differences during landing and cutting tasks and to examine neuromuscular differences between tasks and between dominant and nondominant sides. Design: A 3-way mixed factorial design investigating the effects of sport (basketball, soccer), task (jumping, cutting), and side (dominant, nondominant). Setting: Laboratory. Patients or Other Participants: Thirty high school female athletes who listed either basketball or soccer as their only sport of participation (basketball: n = 15, age = 15.1 ± 1.7 years, experience = 6.9 ± 2.2 years, height = 165.3 ± 7.9 cm, mass = 61.8 ± 9.3 kg; soccer: n = 15, age = 14.8 ± 0.8 years, experience = 8.8 ± 2.5 years, height = 161.8 ± 4.1 cm, mass = 54.6 ± 7.6 kg). Main Outcome Measure(s): Ground reaction forces, stance time, valgus angles, and valgus moments were assessed during (1) a drop vertical jump with an immediate maximal vertical jump and (2) an immediate side-step cut at a 45° angle. Results: Basketball athletes had greater ground reaction forces (P < .001) and decreased stance time (P < .001) during the drop vertical jump, whereas soccer players had greater ground reaction forces (P <.001) and decreased stance time (P < .001) during the cut. Subjects in both sports had greater valgus angles (initial contact and maximum, P = .02 and P = .012, respectively) during cutting than during the drop vertical jump. Greater valgus moments (P = .006) were noted on the dominant side during cutting. Conclusions: Our subjects demonstrated differences in ground reaction forces and stance times during 2 movements associated with noncontact anterior cruciate ligament injuries. Knee valgus moment and angle were significantly influenced by the type of movement performed. Sport-specific neuromuscular training may be warranted, with basketball players focusing on jumping and landing and soccer players focusing on unanticipated cutting maneuvers. PMID:16619097

Increased distance of shooting on basketball jump shot.

PubMed

Okazaki, Victor Hugo Alves; Rodacki, André Luiz Félix

2012-01-01

The present study analyzed the effect of increased distance on basketball jump shot outcome and performance. Ten male expert basketball players were filmed and a number of kinematic variables analyzed during jump shot that were performed from three conditions to represent close, intermediate and far distances (2.8, 4.6, and 6.4m, respectively). Shot accuracy decreased from 59% (close) to 37% (far), in function of the task constraints (p < 0.05). Ball release height decreased (p < 0.05) from 2.46 m (close) to 2.38m (intermediate) and to 2.33m (long). Release angle also decreased (p < 0.05) when shot was performed from close (78.92°) in comparison to intermediate distances (65.60°). While, ball release velocity increased (p < 0.05) from 4.39 m/s (close) to 5.75 m·s(-1) (intermediate) to 6.89 m·s(-1) (far). These changes in ball release height, angle and velocity, related to movement performance adaptations were suggested as the main factors that influence jump shot accuracy when distance is augmented. Key pointsThe increased distance leads to greater spatial con-straint over shot movement that demands an adapta-tion of the movement for the regulation of the accu-racy and the impulse generation to release the ball.The reduction in balls release height and release angle, in addition to the increase in balls release ve-locity, were suggested as the main factors that de-creased shot accuracy with the distance increased.Players should look for release angles of shooting that provide an optimal balls release velocity to im-prove accuracy.

Selected Cognitive Abilities in Elite Youth Soccer Players

PubMed Central

Baláková, Veronika; Boschek, Petr; Skalíková, Lucie

2015-01-01

The identification of talent in soccer is critical to various programs. Although many research findings have been presented, there have been only a few attempts to assess their validity. The aim of this study was to determine the relationship between talent and achievement variables in the Vienna Test System. The participants were 91 Czech soccer players, representing four youth soccer teams, who were born in the year 2000. These boys were divided into two groups according to their coaches’ assessments using a TALENT questionnaire. A two-factor model (component 1: “kinetic finesse”; component 2: “mental strength”) was designed to interpret the responses of the coaches on the questionnaire. The Vienna Test System was used to determine the level of players’ cognitive abilities. In total, the subjects performed seven tests in the following order: Raven’s Standard Progressive Matrices (SPM), a reaction test (RT), a determination test (DT), a visual pursuit test (LVT), a Corsi Block-Tapping Test (CORSI), a time/movement anticipation test (ZBA), and a peripheral perception test (PP). To analyze the relationship between talent and achievement variables within the Vienna Test System, correlation analyses were performed. The results revealed that the talented group attained significantly better results on only 1 of the 16 variables, which was ZBA2: movement anticipation - deviation of movement median (r = .217, p = .019). A comparison of the two talent components showed that component 1 (“kinetic finesse”) was a more significant factor than component 2 (“mental strength”). Although we observed statistically significant correlations, their actual significance remains questionable; thus, further research is required. PMID:26839627

How multi segmental patterns deviate in spastic diplegia from typical developed.

PubMed

Zago, Matteo; Sforza, Chiarella; Bona, Alessia; Cimolin, Veronica; Costici, Pier Francesco; Condoluci, Claudia; Galli, Manuela

2017-10-01

The relationship between gait features and coordination in children with Cerebral Palsy is not sufficiently analyzed yet. Principal Component Analysis can help in understanding motion patterns decomposing movement into its fundamental components (Principal Movements). This study aims at quantitatively characterizing the functional connections between multi-joint gait patterns in Cerebral Palsy. 65 children with spastic diplegia aged 10.6 (SD 3.7) years participated in standardized gait analysis trials; 31 typically developing adolescents aged 13.6 (4.4) years were also tested. To determine if posture affects gait patterns, patients were split into Crouch and knee Hyperextension group according to knee flexion angle at standing. 3D coordinates of hips, knees, ankles, metatarsal joints, pelvis and shoulders were submitted to Principal Component Analysis. Four Principal Movements accounted for 99% of global variance; components 1-3 explained major sagittal patterns, components 4-5 referred to movements on frontal plane and component 6 to additional movement refinements. Dimensionality was higher in patients than in controls (p<0.01), and the Crouch group significantly differed from controls in the application of components 1 and 4-6 (p<0.05), while the knee Hyperextension group in components 1-2 and 5 (p<0.05). Compensatory strategies of children with Cerebral Palsy (interactions between main and secondary movement patterns), were objectively determined. Principal Movements can reduce the effort in interpreting gait reports, providing an immediate and quantitative picture of the connections between movement components. Copyright © 2017 Elsevier Ltd. All rights reserved.

Modern Multi-line Slot Machine Games: The Effect of Lines Wagered on Winners, Losers, Bonuses, and Losses Disguised as Wins.

PubMed

Harrigan, K; Dixon, M; Brown, D

2015-06-01

We simulated the commercially available multi-line slot machine game "Money Storm," including its bonus wins. Our results show that after a specified amount of time (such as 1 or 50 h), when players played a single line, there were marked differences between one player and the next-a few won a lot, others lost far more than average. When playing 20 lines there were fewer big winners and fewer players quickly losing a large percentage of their money. We simulated a Gambler's Ruin scenario whereby players arrived with $100 and made $1 wagers until broke. Again we saw a reduction in the variability among player as the number of lines wagered increased, fewer players lost their entire bankroll quickly, and fewer players had big wins. The bonus wins in Money Storm contribute approximately 24% to the payback of the game, and our simulations of bonus wins shows that with 20 lines wagered the players spend approximately 11% of their time in bonus wins. With one line wagered, there are no losses disguised as wins while with 20 lines wagered the majority of hits are losses disguised as wins. Players using multi-line machines can thus tune the characteristics of the machine gambling experience to match their preferred pattern, though most seem in practice to bet on the most possible lines. Our results serve to inform researchers, counsellors, gamblers and others about how slot machines are designed, and the effect that wagering on multiple lines has on short-term and long-term play, bonus wins, and losses disguised as wins.

Identifying the processes underpinning anticipation and decision-making in a dynamic time-constrained task.

PubMed

Roca, André; Ford, Paul R; McRobert, Allistair P; Mark Williams, A

2011-08-01

A novel, representative task was used to examine skill-based differences in the perceptual and cognitive processes underlying performance on a dynamic, externally paced task. Skilled and less skilled soccer players were required to move and interact with life-size, action sequences involving 11 versus 11 soccer situations filmed from the perspective of a central defender in soccer. The ability of participants to anticipate the intentions of their opponents and to make decisions about how they should respond was measured across two separate experiments. In Experiment 1, visual search behaviors were examined using an eye-movement registration system. In Experiment 2, retrospective verbal reports of thinking were gathered from a new sample of skilled and less skilled participants. Skilled participants were more accurate than less skilled participants at anticipating the intentions of opponents and in deciding on an appropriate course of action. The skilled players employed a search strategy involving more fixations of shorter duration in a different sequential order and toward more disparate and informative locations in the display when compared with the less skilled counterparts. The skilled players generated a greater number of verbal report statements with a higher proportion of evaluation, prediction, and planning statements than the less skilled players, suggesting they employed more complex domain-specific memory representations to solve the task. Theoretical, methodological, and practical implications are discussed.

Context-aware pattern discovery for moving object trajectories

NASA Astrophysics Data System (ADS)

Sharif, Mohammad; Asghar Alesheikh, Ali; Kaffash Charandabi, Neda

2018-05-01

Movement of point objects are highly sensitive to the underlying situations and conditions during the movement, which are known as contexts. Analyzing movement patterns, while accounting the contextual information, helps to better understand how point objects behave in various contexts and how contexts affect their trajectories. One potential solution for discovering moving objects patterns is analyzing the similarities of their trajectories. This article, therefore, contextualizes the similarity measure of trajectories by not only their spatial footprints but also a notion of internal and external contexts. The dynamic time warping (DTW) method is employed to assess the multi-dimensional similarities of trajectories. Then, the results of similarity searches are utilized in discovering the relative movement patterns of the moving point objects. Several experiments are conducted on real datasets that were obtained from commercial airplanes and the weather information during the flights. The results yielded the robustness of DTW method in quantifying the commonalities of trajectories and discovering movement patterns with 80 % accuracy. Moreover, the results revealed the importance of exploiting contextual information because it can enhance and restrict movements.

Multi-Dimensional Pattern Discovery of Trajectories Using Contextual Information

NASA Astrophysics Data System (ADS)

Sharif, M.; Alesheikh, A. A.

2017-10-01

Movement of point objects are highly sensitive to the underlying situations and conditions during the movement, which are known as contexts. Analyzing movement patterns, while accounting the contextual information, helps to better understand how point objects behave in various contexts and how contexts affect their trajectories. One potential solution for discovering moving objects patterns is analyzing the similarities of their trajectories. This article, therefore, contextualizes the similarity measure of trajectories by not only their spatial footprints but also a notion of internal and external contexts. The dynamic time warping (DTW) method is employed to assess the multi-dimensional similarities of trajectories. Then, the results of similarity searches are utilized in discovering the relative movement patterns of the moving point objects. Several experiments are conducted on real datasets that were obtained from commercial airplanes and the weather information during the flights. The results yielded the robustness of DTW method in quantifying the commonalities of trajectories and discovering movement patterns with 80 % accuracy. Moreover, the results revealed the importance of exploiting contextual information because it can enhance and restrict movements.

Ultrasound assessment of the posterior circumflex humeral artery in elite volleyball players: Aneurysm prevalence, anatomy, branching pattern and vessel characteristics.

PubMed

van de Pol, Daan; Maas, Mario; Terpstra, Aart; Pannekoek-Hekman, Marja; Alaeikhanehshir, Sena; Kuijer, P Paul F M; Planken, R Nils

2017-03-01

To determine the prevalence of posterior circumflex humeral artery (PCHA) aneurysms and vessel characteristics of the PCHA and deep brachial artery (DBA) in elite volleyball players. Two-hundred and eighty players underwent standardized ultrasound assessment of the dominant arm by a vascular technologist. Assessment included determination of PCHA aneurysms (defined as segmental vessel dilatation ≥150 %), PCHA and DBA anatomy, branching pattern, vessel course and diameter. The PCHA and DBA were identified in 100 % and 93 % (260/280) of cases, respectively. The prevalence of PCHA aneurysms was 4.6 % (13/280). All aneurysms were detected in proximal PCHA originating from the axillary artery (AA). The PCHA originated from the AA in 81 % of cases (228/280), and showed a curved course dorsally towards the humeral head in 93 % (211/228). The DBA originated from the AA in 73 % of cases (190/260), and showed a straight course parallel to the AA in 93 % (177/190). PCHA aneurysm prevalence in elite volleyball players is high and associated with a specific branching type: a PCHA that originates from the axillary artery. Radiologists should have a high index of suspicion for this vascular overuse injury. For the first time vessel characteristics and reference values are described to facilitate ultrasound assessment. • Prevalence of PCHA aneurysms is 4.6 % among elite volleyball players. • All aneurysms are in proximal PCHA that originates directly from AA. • Vessel characteristics and reference values are described to facilitate US assessment. • Mean PCHA and DBA diameters can be used as reference values. • Radiologists need a high index of suspicion for this vascular overuse injury.

Is there a relationship between the playing position of soccer players and their food and macronutrient intake?

PubMed

Iglesias-Gutiérrez, Eduardo; García, Angela; García-Zapico, Pedro; Pérez-Landaluce, Javier; Patterson, Angeles M; García-Rovés, Pablo Miguel

2012-04-01

Many authors have proposed the necessity of the design and implementation of dietary and nutrition education programs for soccer players, although little information is available about the determinants of food selection and nutrient intake. The aim of this study was to evaluate the nutritional intake and eating patterns of soccer players according to their playing position in the team. Eighty-seven young male soccer players (aged 16-21 years) were recruited from the junior teams of a Spanish First Division Soccer League Club and divided into 6 positional categories (goalkeepers, full-backs, centre-backs, midfielders, wingers, and forwards). Body composition (height, weight, and body fat), performance in soccer-specific tests (jumping, sprinting, and intermittent endurance), and dietary intake (weighed food intake method) were assessed. A spontaneous higher carbohydrate intake was observed for full-backs, midfielders, and wingers (g·kg(-1) body mass: 4.9 ± 1.0, 4.9 ± 1.3, 4.9 ± 0.8; % of energy intake: 47 ± 5, 46 ± 6, 46 ± 4), compared with goalkeepers and centre-backs (g·kg(-1) of body mass: 3.9 ± 1.0, 4.3 ± 1.1; % of energy intake: 44 ± 3, 42 ± 4). These differences were related to food selection patterns, and a higher contribution to daily energy intake of cereals, derivatives, and potatoes was observed between full-backs compared with goalkeepers and centre-backs (33% vs. 27% and 25%). The magnitude of these differences is limited considering the whole diet, and an inadequate nutrient intake were observed in most individuals of every group. The design and implementation of nutrition intervention programs, taking into consideration positional differences in nutritional intake, would be useful for these players.

Multiparametric MRI changes persist beyond recovery in concussed adolescent hockey players.

PubMed

Manning, Kathryn Y; Schranz, Amy; Bartha, Robert; Dekaban, Gregory A; Barreira, Christy; Brown, Arthur; Fischer, Lisa; Asem, Kevin; Doherty, Timothy J; Fraser, Douglas D; Holmes, Jeff; Menon, Ravi S

2017-11-21

To determine whether multiparametric MRI data can provide insight into the acute and long-lasting neuronal sequelae after a concussion in adolescent athletes. Players were recruited from Bantam hockey leagues in which body checking is first introduced (male, age 11-14 years). Clinical measures, diffusion metrics, resting-state network and region-to-region functional connectivity patterns, and magnetic resonance spectroscopy absolute metabolite concentrations were analyzed from an independent, age-matched control group of hockey players (n = 26) and longitudinally in concussed athletes within 24 to 72 hours (n = 17) and 3 months (n = 14) after a diagnosed concussion. There were diffusion abnormalities within multiple white matter tracts, functional hyperconnectivity, and decreases in choline 3 months after concussion. Tract-specific spatial statistics revealed a large region along the superior longitudinal fasciculus with the largest decreases in diffusivity measures, which significantly correlated with clinical deficits. This region also spatially intersected with probabilistic tracts connecting cortical regions where we found acute functional connectivity changes. Hyperconnectivity patterns at 3 months after concussion were present only in players with relatively less severe clinical outcomes, higher choline concentrations, and diffusivity indicative of relatively less axonal disruption. Changes persisted well after players' clinical scores had returned to normal and they had been cleared to return to play. Ongoing white matter maturation may make adolescent athletes particularly vulnerable to brain injury, and they may require extended recovery periods. The consequences of early brain injury for ongoing brain development and risk of more serious conditions such as second impact syndrome or neural degenerative processes need to be elucidated. Copyright © 2017 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.

Injury in the national basketball association: a 17-year overview.

PubMed

Drakos, Mark C; Domb, Benjamin; Starkey, Chad; Callahan, Lisa; Allen, Answorth A

2010-07-01

Injury patterns in elite athletes over long periods continue to evolve. The goal of this study was to review of the injuries and medical conditions afflicting athletes competing in the National Basketball Association (NBA) over a 17-year period. Descriptive epidemiological study. Injuries and player demographic information were reported by each team's athletic trainer. Criteria for reportable injuries were those that resulted in (1) physician referral, (2) a practice or game being missed, or (3) emergency care. The demographics, frequency of injury, time lost, and game exposures were tabulated, and game-related injury rates and 95% confidence intervals were calculated. A total of 1094 players appeared in the database 3843 times (3.3 ± 2.6 seasons). Lateral ankle sprains were the most frequent orthopaedic injury (n, 1658; 13.2%), followed by patellofemoral inflammation (n, 1493; 11.9%), lumbar strains (n, 999; 7.9%), and hamstring strains (n, 413; 3.3%). The most games missed were related to patellofemoral inflammation (n, 10 370; 17.5%), lateral ankle sprains (n, 5223; 8.8%), knee sprains (n, 4369; 7.4%), and lumbar strains (n, 3933; 6.6%). No correlations were found between injury rate and player demographics, including age, height, weight, and NBA experience. Professional athletes in the NBA experience a high rate of game-related injuries. Patellofemoral inflammation is the most significant problem in terms of days lost in competition, whereas ankle sprains are the most common injury. True ligamentous injuries of the knee were surprisingly rare. Importantly, player demographics were not correlated with injury rates. Further investigation is necessary regarding the consequences and sport-specific treatment of various injuries in NBA players. Knowledge of these injury patterns can help to guide treatments and provide more accurate guidelines for an athlete to return to play.

Game Demands of Seven-A-Side Soccer in Young Players.

PubMed

Barbero-Alvarez, José C; Gómez-López, Maite; Castagna, Carlo; Barbero-Alvarez, Verónica; Romero, David V; Blanchfield, Anthony W; Nakamura, Fábio Y

2017-07-01

Barbero-Alvarez, JC, Gómez-López, M, Castagna, C, Barbero-Alvarez, V, Romero, DV, Blanchfield, AW, and Nakamura, FY. Game demands of seven-a-side soccer in young players. J Strength Cond Res 31(7): 1771-1779, 2017-The aim of this study was to examine the activity patterns and physiological demands of 7-a-side youth soccer matches across 2 chronological age categories (U12 and U14). Twenty-two soccer players of a national youth soccer academy were investigated. Players of each age category performed 2 training matches (2 × 25 minutes) and were monitored by global positioning system and heart rate monitor units. Players of both categories covered similar total distance (5,348 ± 307 m), at similar mean heart rate values (86 ± 4% of maximum). However, the number of high-intensity runs (82.5 ± 17.4 vs. 69.7 ± 15.2) and total distance covered during sprints (264 ± 207 vs. 128 ± 74 m) were significantly (p ≤ 0.05) higher in U14 compared with U12. The results suggest a highly demanding nature of 7-a-side soccer for skilled players, with physical maturity possibly influencing the match-related high-intensity performance at these ages.

A Model for Comparing Game Theory and Artificial Intelligence Decision Making Processes

DTIC Science & Technology

1989-12-01

I V. Re-visions to PALANTIR Program .. .. .... .... .... ..... 20 4.1 Rewritten in the C Programming Lanigiiage...The PALANTIR , created by Capt Robert Palmer, had two uses: to train per- sonnel on the use of satellites and to provide insight into the movements...zero-sum game theory approach to reach decisions (11:23). This approach is discussed further in Chapter 2. 2 Although PALANTIR used game theory players

Who Networks? The Social Psychology of Virtual Communities

DTIC Science & Technology

2004-06-01

virtual life: the open side - characterized by communities of interest, civil society movements, virtual “states,” and 4 online gaming communities...network of people hailing from Sicily. Sometimes the offline/ online similari- ties mesh even more, as when a gaming society in a small Swedish town...Commercially owned and regulated graphics-based Massively Multi- Player Gaming Communities (EverQuest, The Matrix Online ®, etc.) • UseNET

The effect of ankle bracing on knee kinetics and kinematics during volleyball-specific tasks.

PubMed

West, T; Ng, L; Campbell, A

2014-12-01

The purpose of this study was to examine the effects of ankle bracing on knee kinetics and kinematics during volleyball tasks. Fifteen healthy, elite, female volleyball players performed a series of straight-line and lateral volleyball tasks with no brace and when wearing an ankle brace. A 14-camera Vicon motion analysis system and AMTI force plate were used to capture the kinetic and kinematic data. Knee range of motion, peak knee anterior-posterior and medial-lateral shear forces, and peak ground reaction forces that occurred between initial contact with the force plate and toe off were compared using paired sample t-tests between the braced and non-braced conditions (P < 0.05). The results revealed no significant effect of bracing on knee kinematics or ground reaction forces during any task or on knee kinetics during the straight-line movement volleyball tasks. However, ankle bracing was demonstrated to reduce knee lateral shear forces during all of the lateral movement volleyball tasks. Wearing the Active Ankle T2 brace will not impact knee joint range of motion and may in fact reduce shear loading to the knee joint in volleyball players. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Effects of forefoot bending stiffness of badminton shoes on agility, comfort perception and lower leg kinematics during typical badminton movements.

PubMed

Park, Sang-Kyoon; Lam, Wing-Kai; Yoon, Sukhoon; Lee, Ki-Kwang; Ryu, Jiseon

2017-09-01

This study investigated whether an increase in the forefoot bending stiffness of a badminton shoe would positively affect agility, comfort and biomechanical variables during badminton-specific movements. Three shoe conditions with identical shoe upper and sole designs with different bending stiffness (Flexible, Regular and Stiff) were used. Elite male badminton players completed an agility test on a standard badminton court involving consecutive lunges in six directions, a comfort test performed by a pair of participants conducting a game-like practice trial and a biomechanics test involving a random assignment of consecutive right forward lunges. No significant differences were found in agility time and biomechanical variables among the three shoes. The players wearing the shoe with a flexible forefoot outsole demonstrated a decreased perception of comfort in the forefoot cushion compared to regular and stiffer conditions during the comfort test (p < 0.05). The results suggested that the modification of forefoot bending stiffness would influence individual perception of comfort but would not influence performance and lower extremity kinematics during the tested badminton-specific tasks. It was concluded that an optimisation of forefoot structure and materials in badminton shoes should consider the individual's perception to maximise footwear comfort in performance.

Exploratory Movement Generates Higher-Order Information That Is Sufficient for Accurate Perception of Scaled Egocentric Distance

PubMed Central

Mantel, Bruno; Stoffregen, Thomas A.; Campbell, Alain; Bardy, Benoît G.

2015-01-01

Body movement influences the structure of multiple forms of ambient energy, including optics and gravito-inertial force. Some researchers have argued that egocentric distance is derived from inferential integration of visual and non-visual stimulation. We suggest that accurate information about egocentric distance exists in perceptual stimulation as higher-order patterns that extend across optics and inertia. We formalize a pattern that specifies the egocentric distance of a stationary object across higher-order relations between optics and inertia. This higher-order parameter is created by self-generated movement of the perceiver in inertial space relative to the illuminated environment. For this reason, we placed minimal restrictions on the exploratory movements of our participants. We asked whether humans can detect and use the information available in this higher-order pattern. Participants judged whether a virtual object was within reach. We manipulated relations between body movement and the ambient structure of optics and inertia. Judgments were precise and accurate when the higher-order optical-inertial parameter was available. When only optic flow was available, judgments were poor. Our results reveal that participants perceived egocentric distance from the higher-order, optical-inertial consequences of their own exploratory activity. Analysis of participants’ movement trajectories revealed that self-selected movements were complex, and tended to optimize availability of the optical-inertial pattern that specifies egocentric distance. We argue that accurate information about egocentric distance exists in higher-order patterns of ambient energy, that self-generated movement can generate these higher-order patterns, and that these patterns can be detected and used to support perception of egocentric distance that is precise and accurate. PMID:25856410

Retention of movement pattern changes after a lower extremity injury prevention program is affected by program duration.

PubMed

Padua, Darin A; DiStefano, Lindsay J; Marshall, Stephen W; Beutler, Anthony I; de la Motte, Sarah J; DiStefano, Michael J

2012-02-01

Changes in movement patterns have been repeatedly observed immediately after completing a lower extremity injury prevention program. However, it is not known if movement pattern changes are maintained after discontinuing the training program. The ability to maintain movement pattern changes after training has ceased may be influenced by the program's duration. The authors hypothesized that among individuals who completed either a 3-month or 9-month training program and who demonstrated immediate movement pattern changes, only those who completed the 9-month training program would maintain movement pattern changes after a 3-month period of no longer performing the exercises. Cohort study; Level of evidence, 2. A total of 140 youth soccer athletes from 15 separate teams volunteered to participate. Athletes' movement patterns were assessed using the Landing Error Scoring System (LESS) at pretest, posttest, and 3 months after ceasing the program (retention test). Eighty-four of the original 140 participants demonstrated improvements in their LESS scores between pretest and posttest (change in LESS score >0) and were included in the final analyses for this study (n = 84; 20 boys and 64 girls; mean age, 14 ± 2 years; age range, 11-17 years). Teams performed 3-month (short-duration group) and 9-month (extended-duration group) injury prevention programs. The exercises performed were identical for both groups. Teams performed the programs as part of their normal warm-up routine. Although both groups improved their total LESS scores from pretest to posttest, only the extended-duration training group retained their improvements 3 months after ceasing the injury prevention program (F(2,137) = 3.38; P = .04). Results suggest that training duration may be an important factor to consider when designing injury prevention programs that facilitate long-term changes in movement control.

Losing dexterity: patterns of impaired coordination of finger movements in musician’s dystonia

PubMed Central

Furuya, Shinichi; Tominaga, Kenta; Miyazaki, Fumio; Altenmüller, Eckart

2015-01-01

Extensive training can bring about highly-skilled action, but may also impair motor dexterity by producing involuntary movements and muscular cramping, as seen in focal dystonia (FD) and tremor. To elucidate the underlying neuroplastic mechanisms of FD, the present study addressed the organization of finger movements during piano performance in pianists suffering from the condition. Principal component (PC) analysis identified three patterns of fundamental joint coordination constituting finger movements in both patients and controls. The first two coordination patterns described less individuated movements between the “dystonic” finger and key-striking fingers for patients compared to controls. The third coordination pattern, representing the individuation of movements between the middle and ring fingers, was evident during a sequence of strikes with these fingers in controls, which was absent in the patients. Consequently, rhythmic variability of keystrokes was more pronounced during this sequence of strikes for the patients. A stepwise multiple-regression analysis further identified greater variability of keystrokes for individuals displaying less individuated movements between the affected and striking fingers. The findings suggest that FD alters dexterous joint coordination so as to lower independent control of finger movements, and thereby degrades fine motor control. PMID:26289433

The usefulness of GPS telemetry to study wolf circadian and social activity

USGS Publications Warehouse

Merrill, S.B.; David, Mech L.

2003-01-01

This study describes circadian and social movement patterns of 9 wolves and illustrates capabilities and limitations of Global Positioning System (GPS) telemetry for analysis of animal activity patterns. Wolves were studied at the Camp Ripley National Guard Training Site in Little Falls, Minnesota, and were captured via helicopter net-gunning. All study wolves showed nocturnal movement patterns regardless of time of year. One wolf's movement pattern switched to diurnal when he conducted an extraterritorial foray from his natal territory. All data sets with GPS intervals ???1 hour (n = 4) showed crepuscular movement peaks. We identified patterns of den visitation and attendance, estimated minimum distances traveled and minimum rates of movement, and observed that GPS location intervals may affect perceived rates of wolf travel. Global Positioning System telemetry was useful in determining when pack members were traveling together or apart and how long a breeding female wolf spent near her pups (e.g., 10-month-old pups were left unattended by their mother for as long as 17 days).

Passive Transport Disrupts Grid Signals in the Parahippocampal Cortex.

PubMed

Winter, Shawn S; Mehlman, Max L; Clark, Benjamin J; Taube, Jeffrey S

2015-10-05

Navigation is usually thought of relative to landmarks, but neural signals representing space also use information generated by an animal's movements. These signals include grid cells, which fire at multiple locations, forming a repeating grid pattern. Grid cell generation depends upon theta rhythm, a 6-10 Hz electroencephalogram (EEG) oscillation that is modulated by the animals' movement velocity. We passively moved rats in a clear cart to eliminate motor related self-movement cues that drive moment-to-moment changes in theta rhythmicity. We found that passive movement maintained theta power and frequency at levels equivalent to low active movement velocity, spared overall head-direction (HD) cell characteristics, but abolished both velocity modulation of theta rhythmicity and grid cell firing patterns. These results indicate that self-movement motor cues are necessary for generating grid-specific firing patterns, possibly by driving velocity modulation of theta rhythmicity, which may be used as a speed signal to generate the repeating pattern of grid cells. Copyright © 2015 Elsevier Ltd. All rights reserved.

Passive Transport Disrupts Grid Signals in the Parahippocampal Cortex

PubMed Central

Winter, Shawn S.; Mehlman, Max L.; Clark, Benjamin J.; Taube, Jeffrey S.

2015-01-01

Summary Navigation is usually thought of relative to landmarks, but neural signals representing space also use information generated by an animal’s movements. These signals include grid cells, which fire at multiple locations forming a repeating grid pattern. Grid cell generation depends upon theta rhythm, a 6-10 Hz EEG oscillation that is modulated by the animals’ movement velocity. We passively moved rats in a clear cart to eliminate motor related self-movement cues that drive moment-to-moment changes in theta rhythmicity. We found that passive movement maintained theta power and frequency at levels equivalent to low active movement velocity, spared overall HD cell characteristics, and abolished velocity modulation of theta rhythmicity and grid cell firing patterns. These results indicate that self-movement motor cues are necessary for generating grid-specific firing patterns, possibly by driving velocity modulation of theta rhythmicity. Velocity modulation of theta may be used as a speed signal to generate the repeating pattern of grid cells. PMID:26387719

Time series association learning

DOEpatents

Papcun, George J.

1995-01-01

An acoustic input is recognized from inferred articulatory movements output by a learned relationship between training acoustic waveforms and articulatory movements. The inferred movements are compared with template patterns prepared from training movements when the relationship was learned to regenerate an acoustic recognition. In a preferred embodiment, the acoustic articulatory relationships are learned by a neural network. Subsequent input acoustic patterns then generate the inferred articulatory movements for use with the templates. Articulatory movement data may be supplemented with characteristic acoustic information, e.g. relative power and high frequency data, to improve template recognition.

Individual-level movement bias leads to the formation of higher-order social structure in a mobile group of baboons.

PubMed

Bonnell, Tyler R; Clarke, Parry M; Henzi, S Peter; Barrett, Louise

2017-07-01

In mobile social groups, influence patterns driving group movement can vary between democratic and despotic. The arrival at any single pattern of influence is thought to be underpinned by both environmental factors and group composition. To identify the specific patterns of influence driving travel decision-making in a chacma baboon troop, we used spatially explicit data to extract patterns of individual movement bias. We scaled these estimates of individual-level bias to the level of the group by constructing an influence network and assessing its emergent structural properties. Our results indicate that there is heterogeneity in movement bias: individual animals respond consistently to particular group members, and higher-ranking animals are more likely to influence the movement of others. This heterogeneity resulted in a group-level network structure that consisted of a single core and two outer shells. Here, the presence of a core suggests that a set of highly interdependent animals drove routine group movements. These results suggest that heterogeneity at the individual level can lead to group-level influence structures, and that movement patterns in mobile social groups can add to the exploration of both how these structures develop (i.e. mechanistic aspects) and what consequences they have for individual- and group-level outcomes (i.e. functional aspects).

Individual-level movement bias leads to the formation of higher-order social structure in a mobile group of baboons

PubMed Central

Clarke, Parry M.; Henzi, S. Peter; Barrett, Louise

2017-01-01

In mobile social groups, influence patterns driving group movement can vary between democratic and despotic. The arrival at any single pattern of influence is thought to be underpinned by both environmental factors and group composition. To identify the specific patterns of influence driving travel decision-making in a chacma baboon troop, we used spatially explicit data to extract patterns of individual movement bias. We scaled these estimates of individual-level bias to the level of the group by constructing an influence network and assessing its emergent structural properties. Our results indicate that there is heterogeneity in movement bias: individual animals respond consistently to particular group members, and higher-ranking animals are more likely to influence the movement of others. This heterogeneity resulted in a group-level network structure that consisted of a single core and two outer shells. Here, the presence of a core suggests that a set of highly interdependent animals drove routine group movements. These results suggest that heterogeneity at the individual level can lead to group-level influence structures, and that movement patterns in mobile social groups can add to the exploration of both how these structures develop (i.e. mechanistic aspects) and what consequences they have for individual- and group-level outcomes (i.e. functional aspects). PMID:28791140

The effect of a novel movement strategy in decreasing ACL risk factors in female adolescent soccer players

PubMed Central

Celebrini, Richard G.; Eng, Janice J.; Miller, William C.; Ekegren, Christina L.; Johnston, James D.; MacIntyre, Donna L.

2015-01-01

There is a need to investigate the effect of specific movement strategies in reducing biomechanical risk factors for ACL injury in young female athletes. The purpose of this study was 1) to determine the feasibility of implementing a novel movement strategy (Core-PAC) into a team warm-up prior to soccer training based on subject compliance and integration of the Core-PAC into the warm-up and 2) to determine whether the Core-PAC would improve peak knee flexion angles and peak abduction moments at the knee during a side-cut (SC) and an unanticipated side-cut (USC) prior to kicking a soccer ball, and a side-hop (SH) task after immediate instruction and after a four-week training program. A convenience sample of ten 14–16 year old female soccer players were instructed in the Core-PAC immediately after baseline testing and during a training program consisting of a 20-minute warm-up, two-times per week. The Core-PAC was understood and accepted by the subjects and incorporated into their warm-up activities with good compliance. After the immediate instruction, there were significant increases in peak knee flexion angles of a mean 6.4° during the SC (p = 0.001), 3.5° during the USC (p = 0.007), and 5.8° during the SH (p < 0.001) tasks. Peak knee abduction moments decreased by a mean of 0.25 Nm/kg during the SC (p < 0.03), 0.17 Nm/kg during the USC (p = 0.05), and 0.27 Nm/kg during the SH (p = 0.04) tasks. After the 4-week training program, some individuals showed improvement. The results of this study suggest that the Core-PAC may be one method of modifying high-risk movements for ACL injury such as side-cutting and single-leg landing. PMID:22210470

Step selection techniques uncover the environmental predictors of space use patterns in flocks of Amazonian birds.

PubMed

Potts, Jonathan R; Mokross, Karl; Stouffer, Philip C; Lewis, Mark A

2014-12-01

Understanding the behavioral decisions behind animal movement and space use patterns is a key challenge for behavioral ecology. Tools to quantify these patterns from movement and animal-habitat interactions are vital for transforming ecology into a predictive science. This is particularly important in environments undergoing rapid anthropogenic changes, such as the Amazon rainforest, where animals face novel landscapes. Insectivorous bird flocks are key elements of avian biodiversity in the Amazonian ecosystem. Therefore, disentangling and quantifying the drivers behind their movement and space use patterns is of great importance for Amazonian conservation. We use a step selection function (SSF) approach to uncover environmental drivers behind movement choices. This is used to construct a mechanistic model, from which we derive predicted utilization distributions (home ranges) of flocks. We show that movement decisions are significantly influenced by canopy height and topography, but depletion and renewal of resources do not appear to affect movement significantly. We quantify the magnitude of these effects and demonstrate that they are helpful for understanding various heterogeneous aspects of space use. We compare our results to recent analytic derivations of space use, demonstrating that the analytic approximation is only accurate when assuming that there is no persistence in the animals' movement. Our model can be translated into other environments or hypothetical scenarios, such as those given by proposed future anthropogenic actions, to make predictions of spatial patterns in bird flocks. Furthermore, our approach is quite general, so could potentially be used to understand the drivers of movement and spatial patterns for a wide variety of animal communities.

Step selection techniques uncover the environmental predictors of space use patterns in flocks of Amazonian birds

PubMed Central

Potts, Jonathan R; Mokross, Karl; Stouffer, Philip C; Lewis, Mark A

2014-01-01

Understanding the behavioral decisions behind animal movement and space use patterns is a key challenge for behavioral ecology. Tools to quantify these patterns from movement and animal–habitat interactions are vital for transforming ecology into a predictive science. This is particularly important in environments undergoing rapid anthropogenic changes, such as the Amazon rainforest, where animals face novel landscapes. Insectivorous bird flocks are key elements of avian biodiversity in the Amazonian ecosystem. Therefore, disentangling and quantifying the drivers behind their movement and space use patterns is of great importance for Amazonian conservation. We use a step selection function (SSF) approach to uncover environmental drivers behind movement choices. This is used to construct a mechanistic model, from which we derive predicted utilization distributions (home ranges) of flocks. We show that movement decisions are significantly influenced by canopy height and topography, but depletion and renewal of resources do not appear to affect movement significantly. We quantify the magnitude of these effects and demonstrate that they are helpful for understanding various heterogeneous aspects of space use. We compare our results to recent analytic derivations of space use, demonstrating that the analytic approximation is only accurate when assuming that there is no persistence in the animals' movement. Our model can be translated into other environments or hypothetical scenarios, such as those given by proposed future anthropogenic actions, to make predictions of spatial patterns in bird flocks. Furthermore, our approach is quite general, so could potentially be used to understand the drivers of movement and spatial patterns for a wide variety of animal communities. PMID:25558353

Neuroleptic-induced movement disorders in a naturalistic schizophrenia population: diagnostic value of actometric movement patterns.

PubMed

Janno, Sven; Holi, Matti M; Tuisku, Katinka; Wahlbeck, Kristian

2008-04-18

Neuroleptic-induced movement disorders (NIMDs) have overlapping co-morbidity. Earlier studies have described typical clinical movement patterns for individual NIMDs. This study aimed to identify specific movement patterns for each individual NIMD using actometry. A naturalistic population of 99 schizophrenia inpatients using conventional antipsychotics and clozapine was evaluated. Subjects with NIMDs were categorized using the criteria for NIMD found in the Diagnostic and Statistical Manual for Mental Disorders - Fourth Edition (DSM-IV).Two blinded raters evaluated the actometric-controlled rest activity data for activity periods, rhythmical activity, frequencies, and highest acceleration peaks. A simple subjective question was formulated to test patient-based evaluation of NIMD. The patterns of neuroleptic-induced akathisia (NIA) and pseudoakathisia (PsA) were identifiable in actometry with excellent inter-rater reliability. The answers to the subjective question about troubles with movements distinguished NIA patients from other patients rather well. Also actometry had rather good screening performances in distinguishing akathisia from other NIMD. Actometry was not able to reliably detect patterns of neuroleptic-induced parkinsonism and tardive dyskinesia. The present study showed that pooled NIA and PsA patients had a different pattern in lower limb descriptive actometry than other patients in a non-selected sample. Careful questioning of patients is a useful method of diagnosing NIA in a clinical setting.

Functional MRI reveals expert-novice differences during sport-related anticipation.

PubMed

Wright, Michael J; Bishop, Daniel T; Jackson, Robin C; Abernethy, Bruce

2010-01-27

We examined the effect of expertise on cortical activation during sports anticipation using functional MRI. In experiment 1, recreational players predicted badminton stroke direction and the pattern of active clusters was consistent with a proposed perception-of-action network. This pattern was not replicated in a stimulus-matched, action-unrelated control task. In experiment 2, players of three different skill levels anticipated stroke direction from clips occluded either 160 ms before or 80 ms after racquet-shuttle contact. Early-occluded sequences produced more activation than late-occluded sequences overall, in most cortical regions of interest, but experts showed an additional enhancement in medial, dorsolateral and ventrolateral frontal cortex. Anticipation in open-skill sports engages cortical areas integral to observing and understanding others' actions; such activity is enhanced in experts.

Do players and staff sleep more during the pre- or competitive season of elite rugby league?

PubMed

Caia, Johnpaul; Scott, Tannath J; Halson, Shona L; Kelly, Vincent G

2017-09-01

This study establishes the sleep behaviour of players and staff during the pre- and competitive seasons of elite rugby league. For seven days during both the pre- and competitive seasons, seven rugby league players and nine full-time staff from one professional Australian rugby league club had their sleep monitored via wrist actigraphy and self-report sleep diaries. Two-way repeated measures analysis of variance determined differences between the pre- and competitive season in players and staff, with effect sizes (ES) used to interpret the practical magnitude of differences. Findings show an earlier bed time and wake time for players (-34 min, ES = 1.5; ±0.5 and -39 min, 2.1; ±0.5 respectively) and staff (-29 min, ES = 0.8; ±0.3 and -35 min, ES = 1.7; ±0.4 respectively) during pre-season when compared to the competitive season. Despite this, no differences were seen when considering the amount of time in bed, sleep duration or sleep efficiency obtained between the pre- and competitive seasons. Our results suggest that early morning training sessions scheduled during pre-season advances wake time in elite rugby league. However, both players and staff can aim to avoid reductions in sleep duration and sleep efficiency with subsequent adjustment of night time sleep patterns. This may be particularly pertinent for staff, who wake earlier than players during both the pre- and competitive seasons.

Injury Pattern in Icelandic Elite Male Handball Players.

PubMed

Rafnsson, Elis Thor; Valdimarsson, Örnólfur; Sveinsson, Thorarinn; Árnason, Árni

2017-10-10

To examine the incidence, type, location, and severity of injuries in Icelandic elite male handball players and compare across factors like physical characteristics and playing position. Prospective cohort study. The latter part of the preseason and the competitive season of Icelandic male handball. Eleven handball teams (185 players) from the 2 highest divisions in Iceland participated in the study. Six teams (109 players) completed the study. Injuries were recorded by the players under supervision from their team physiotherapists or coaches. Coaches recorded training exposure, and match exposure was obtained from the Icelandic and European Handball Federations. The players directly recorded potential risk factors, such as age, height, weight, previous injuries, and player position. Injury incidence and injury location and number of injury days. Recorded time-loss injuries were 86, of which 53 (62%) were acute and 33 (38%) were due to overuse. The incidence of acute injuries was 15.0 injuries/1000 hours during games and 1.1 injuries/1000 hours during training sessions. No significant difference was found in injury incidence between teams, but number of injury days did differ between teams (P = 0.0006). Acute injuries were most common in knees (26%), ankles (19%), and feet/toes (17%), but overuse injuries occurred in low back/pelvic region (39%), shoulders (21%), and knees (21%). Previous knee injuries were the only potential risk factor found for knee injury. The results indicate a higher rate of overuse injuries in low back/pelvic region and shoulders than in comparable studies.

Movement characteristics of persons with prader-willi syndrome rising from supine.

PubMed

Belt, A B; Hertel, T A; Mante, J R; Marks, T; Rockett, V L; Wade, C; Clayton-Krasinski, D

2001-01-01

The purposes of this study were to: 1) determine if previously published descriptors of the supine to stand rising task in healthy individuals could be applied to the movements of persons with Prader-Willi Syndrome (PWS); and 2) assess upper extremity (UE), axial region (AX), and lower extremity (LE) movements among subjects with PWS compared with controls. Nine subjects with PWS (seven-36 years of age) and matched controls were videotaped performing 10 rising trials. The UE, AX, and LE movements were classified using published descriptors. Occurrence frequencies of movement patterns, duration of movement, and the relationships among body region movement score, BMI, and age were determined. Subjects with PWS utilized developmentally less advanced asymmetrical rising patterns, took longer to rise, and demonstrated less within subject variability than controls. Categorical descriptors, with minor modifications, can be used to describe rising movements in persons with PWS. Knowledge of successful rising patterns may assist PTs when examining or planning intervention strategies for teaching the rising task.