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Sample records for quadriceps femoris influences

  1. New aspects of the influence of quadriceps femoris muscle stimulation course on functional capabilities of the organism.

    PubMed

    Arkov, V V; Abramova, T F; Nikitina, T M; Afanasjeva, D A; Anosova, A A; Milenina, A I; Tonevitsky, A G

    2010-08-01

    We studied the effect of a course of electrical stimulation of the quadriceps femoris muscle with submaximal contraction under biofeedback conditions on functional capabilities of the organism. In addition to the known effects, electrostimulation course modulated the content of intra- and extracellular fluid and increases MDA content and creatine phosphokinase activity, which can be a manifestation of overtreatment. Impairment of body static balance after the course was revealed. Thus, monitoring of the effects of electrostimulation is required during the course.

  2. Foam Rolling of Quadriceps Decreases Biceps Femoris Activation.

    PubMed

    Cavanaugh, Mark Tyler; Aboodarda, Saied Jalal; Hodgson, Daniel; Behm, David George

    2016-09-06

    Foam rolling has been shown to increase range of motion without subsequent performance impairments of the rolled muscle, however, there are no studies examining rolling effects on antagonist muscles. The objective of this study was to determine whether foam rolling the hamstrings and/or quadriceps would affect hamstrings and quadriceps activation in men and women. Recreationally active men (n=10, 25 ± 4.6 years, 180.1 ± 4.4 cm, 86.5 ± 15.7 kg) and women (n=8, 21.75 ± 3.2 years, 166.4 ± 8.8 cm, 58.9 ± 7.9 kg) had surface electromyographic activity analyzed in the dominant vastus lateralis (VL), vastus medialis (VM), and biceps femoris (BF) muscles upon a single leg landing from a hurdle jump under four conditions. Conditions included rolling of the hamstrings, quadriceps, both muscle groups and a control session. BF activation significantly decreased following quadriceps foam rolling (F(1,16) = 7.45, p = 0.015, -8.9%). There were no significant changes in quadriceps activation following hamstrings foam rolling. This might be attributed to the significantly greater levels of perceived pain with quadriceps rolling applications (F(1,18) = 39.067, p < 0.001, 98.2%). There were no sex-based changes in activation following foam rolling for VL (F(6,30) = 1.31, p = 0.283) VM (F(6,30) = 1.203, p = 0.332) or BF (F(6,36) = 1.703, p = 0.199). Antagonist muscle activation may be altered following agonist foam rolling, however, it can be suggested that any changes in activation are likely a result of reciprocal inhibition due to increased agonist pain perception.

  3. Optimal Burst Duration During a Facilitated Quadriceps Femoris Contraction

    PubMed Central

    McLoda, Todd A.; Carmack, Jennifer A.

    2000-01-01

    Objective: To determine the most efficient burst duty cycle for eliciting an involuntary quadriceps femoris contraction in healthy subjects. This information will allow clinicians to make an informed decision about the optimal burst duty cycle based upon a specific treatment goal. The logical goal for such a treatment choice is to enhance motor unit recruitment in an effort to maintain postoperative or postinjury strength, when voluntary contractions may be less effective. Design and Setting: Single-group and 5-measures design. All tests were performed in a university laboratory. Subjects: Forty-eight healthy subjects (27 men and 21 women; mean age, 26.4 ± 8.5 years) performed a maximal voluntary isometric contraction (MVIC) on an isokinetic device and received neuromuscular electrical stimulation (NMES) at 5 different burst duty cycles. Measurements: Subjects first performed an MVIC for knee extension on an isokinetic dynamometer at 60° of knee flexion. NMES surface electrodes were applied to the quadriceps muscle of each subject's dominant leg. The values for the NMES were 2500-Hz carrier frequency, 50-bursts-per-second treatment frequency, amplitude increased to maximum tolerance, and burst duty cycle set to each of the 5 comparison values. The peak isometric force generated by each of the 5 nonvolitional contractions was recorded, along with the maximal charge per burst tolerated by each subject. Force generated was described as percentage of MVIC. Efficiency was the amount of force per burst charge. Results: The mean MVIC achieved by the subjects was 553.8 newtons (N). The average force per burst charge generated at 10% burst duty cycle was 132.9 N; at 30%, 104.2 N; at 50%, 93.1 N; at 70%, 52.9 N; and at 90%, 41.3 N. The average efficiency (force per millicoulombs [mC]) at 10% burst duty cycle was the highest at 6.49 N/mC and at 90% was the lowest at 1.05 N/mC. Conclusions: A burst duty cycle of 10% was the most efficient ratio of burst duration to

  4. Continuous Femoral Nerve Blocks: Decreasing Local Anesthetic Concentration to Minimize Quadriceps Femoris Weakness

    PubMed Central

    Bauer, Maria; Wang, Lu; Onibonoje, Olusegun K.; Parrett, Chad; Sessler, Daniel I.; Mounir-Soliman, Loran; Zaky, Sherif; Krebs, Viktor; Buller, Leonard T.; Donohue, Michael C.; Stevens-Lapsley, Jennifer E.; Ilfeld, Brian M.

    2012-01-01

    Background Whether decreasing the local anesthetic concentration during a continuous femoral nerve block results in less quadriceps weakness remains unknown. Methods Preoperatively, bilateral femoral perineural catheters were inserted in patients undergoing bilateral knee arthroplasty (n = 36) at a single clinical center. Postoperatively, right-sided catheters were randomly assigned to receive perineural ropivacaine of either 0.1% (basal 12 mL/h; bolus 4 mL) or 0.4% (basal 3 mL/h; bolus 1 mL), with the left catheter receiving the alternative concentration/rate in an observer- and subject-masked fashion. The primary endpoint was the maximum voluntary isometric contraction of the quadriceps femoris muscles the morning of postoperative day 2. Equivalence of treatments would be concluded if the 95% confidence interval for the difference fell within the interval of −20% to 20%. Secondary endpoints included active knee extension, passive knee flexion, tolerance to cutaneous electrical current applied over the distal quadriceps tendon, dynamic pain scores, opioid requirements, and ropivacaine consumption. Results Quadriceps maximum voluntary isometric contraction for limbs receiving 0.1% ropivacaine was a mean (SD) of 13 (8) N·m, versus 12 (8) N·m for limbs receiving 0.4% [intra-subject difference of 3 (40) percentage points; 95% CI −10 to 17; p = 0.63]. Because the 95% confidence interval fell within prespecified tolerances, we conclude that the effect of the two concentrations were equivalent. Similarly, there were no statistically significant differences in secondary endpoints. Conclusions For continuous femoral nerve blocks, we found no evidence that local anesthetic concentration and volume influence block characteristics, suggesting that local anesthetic dose (mass) is the primary determinant of perineural infusion effects. PMID:22293719

  5. Hemipelvectomy for Buttock Tumors Utilizing an Anterior Myocutaneous Flap of Quadriceps Femoris Muscle

    PubMed Central

    Sugarbaker, Paul H.; Chretien, Paul A.

    1983-01-01

    Hemipelvectomy utilizing an anterior myocutaneous flap is indicated for aggressive tumors of the buttock and proximal portion of the posterior thigh. A large operative defect created posteriorly by amputation of the lower extremity, hemipelvis, and buttock is covered by a myocutaneous flap of quadriceps femoris muscle and overlying skin and subcutaneous tissue. The superficial femoral artery is preserved to sustain the myocutaneous flap. ImagesFig. 2A,B,C.Fig. 2A,B,C. PMID:6848048

  6. Evaluation of Electromyographic Biofeedback for the Quadriceps Femoris: A Systematic Review

    PubMed Central

    Wasielewski, Noah J.; Parker, Tonya M.; Kotsko, Kevin M.

    2011-01-01

    Objective: To critically review evidence for the effectiveness of electromyographic biofeedback (EMGB) of the quadriceps femoris muscle in treating various knee conditions. Data Sources: Databases used to locate randomized controlled trials included PubMed (1980–2010), Cumulative Index of Nursing and Allied Health Literature (CINAHL, 1995–2007), Web of Science (1986–2010), SPORTDiscus (1990–2007), and Physiotherapy Evidence Database (PEDro). Key words were knee and biofeedback. Study Selection: The criteria for selection were clinical randomized controlled trials in which EMGB of the quadriceps femoris was used for various knee conditions of musculoskeletal origin. Trials were excluded because of research designs other than randomized controlled trials, articles published in a non-English language, inclusion of healthy research participants, inability to identify EMGB as the source of clinical improvement, and lack of pain, functional outcome, or quadriceps torque as outcome measures. Data Extraction: Twenty specific data points were abstracted from each clinical trial under the broad categories of attributes of the patient and injury, treatment variables for the EMGB group, treatment variables for the control group, and attributes of the research design. Data Synthesis: Eight trials yielded a total of 319 participants with patellofemoral pain syndrome (n = 86), anterior cruciate ligament reconstruction (n = 52), arthroscopic surgery (n = 91), or osteoarthritis (n = 90). The average methodologic score of the included studies was 4.6/10 based on PEDro criteria. Pooled analyses demonstrated heterogeneity of the included studies, rendering the interpretation of the pooled data inappropriate. The EMGB appeared to benefit short-term postsurgical pain or quadriceps strength in 3 of 4 postsurgical investigations but was ineffective for chronic knee conditions such as patellofemoral pain and osteoarthritis in all 4 studies. Because the findings are based on limited

  7. Measurement of the quadriceps femoris muscle using magnetic resonance and ultrasound imaging.

    PubMed Central

    Walton, J M; Roberts, N; Whitehouse, G H

    1997-01-01

    OBJECTIVES: To define a method for measurement of the cross sectional area and volume of the quadriceps femoris muscle using magnetic resonance imaging (MRI) in conjunction with stereology, and to compare the results of measurements obtained by the MRI method with those obtained by the conventional method of static B-mode ultrasound in order to evaluate whether MRI is a reliable alternative to ultrasound. METHODS: A preliminary MRI study was undertaken on a single female volunteer in order to optimise the scanning technique and sampling design for estimating the muscle volume using the Cavalieri method. Ten healthy volunteers participated in the method comparison study. Each volunteer underwent static B-mode ultrasonography, immediately followed by MRI. The cross sectional area of the quadriceps femoris was estimated at the junction of the proximal one third and distal two thirds of the thigh, and seven systematic sections of the thigh were obtained in order to estimate muscle volume by both modalities. RESULTS: Seven sections through the muscle are required to achieve a coefficient of error of 4-5%. There was no significant difference in the cross sectional area estimates or volume estimates when ultrasound and MRI were compared. CONCLUSION: Muscle cross sectional area and volume can be measured without bias by MRI in conjunction with stereological methods and the method is a reliable alternative to static B-mode ultrasound for this purpose. Images Figure 1 Figure 4 Figure 5 PMID:9132215

  8. Intra- and intermuscular variation in human quadriceps femoris architecture assessed in vivo

    PubMed Central

    Blazevich, Anthony J; Gill, Nicholas D; Zhou, Shi

    2006-01-01

    Despite the functional importance of the human quadriceps femoris in movements such as running, jumping, lifting and climbing, and the known effects of muscle architecture on muscle function, no research has fully described the complex architecture of this muscle group. We used ultrasound imaging techniques to measure muscle thickness, fascicle angle and fascicle length at multiple regions of the four quadriceps muscles in vivo in 31 recreationally active, but non-strength-trained adult men and women. Our analyses revealed a reasonable similarity in the superficial quadriceps muscles, which is suggestive of functional similarity (at least during the uni-joint knee extension task) given that they act via a common tendon. The deep vastus intermedius (VI) is architecturally dissimilar and therefore probably serves a different function(s). Architecture varies significantly along the length of the superficial muscles, which has implications for the accuracy of models that assume a constant intramuscular architecture. It might also have consequences for the efficiency of intra- and intermuscular force transmission. Our results provide some evidence that subjects with a given architecture of one superficial muscle, relative to the rest of the subject sample, also have a similar architecture in other superficial muscles. However, this is not necessarily true for vastus lateralis (VL), and was not the case for VI. Therefore, the relative architecture of one muscle cannot confidently be used to estimate the relative architecture of another. To confirm this, we calculated a value of whole quadriceps architecture by four different methods. Regardless of the method used, we found that the absolute or relative architecture of one muscle could not be used as an indicator of whole quadriceps architecture, although vastus medialis, possibly in concert with VL and the anterior portion of VI, could be used to provide a useful snapshot. Importantly, our estimates of whole quadriceps

  9. Angle- and gender-specific quadriceps femoris muscle recruitment and knee extensor torque.

    PubMed

    Pincivero, Danny M; Salfetnikov, Yuliya; Campy, Robert M; Coelho, Alan J

    2004-11-01

    The objectives were to examine knee angle-, and gender-specific knee extensor torque output and quadriceps femoris (QF) muscle recruitment during maximal effort, voluntary contractions. Fourteen young adult men and 15 young adult women performed three isometric maximal voluntary contractions (MVC), in a random order, with the knee at 0 degrees (terminal extension), 10 degrees, 30 degrees, 50 degrees, 70 degrees, and 90 degrees flexion. Knee extensor peak torque (PT), and average torque (AT) were expressed in absolute (N m), relative (N m kg(-1)) and allometric-modeled (N m kg(-n)) units. Vastus medialis (VM), vastus lateralis (VL), and rectus femoris (RF) muscle EMG signals were full-wave rectified and integrated over the middle 3 s of each contraction, averaged over the three trials at each knee angle, and normalized to the activity recorded at 0 degrees. Muscle recruitment efficiency was calculated as the ratio of the normalized EMG of each muscle to the allometric-modeled average torque (normalized to the values at 0 degrees flexion), and expressed as a percent. Men generated significantly greater knee extensor PT and AT than women in absolute, relative and allometric-modeled units. Absolute and relative PT and AT were significantly highest at 70 degrees, while allometric-modeled values were observed to increase significantly across knee joint angles 10-90 degrees. VM EMG was significantly greater than the VL and RF muscles across all angles, and followed a similar pattern to absolute knee extensor torque. Recruitment efficiency improved across knee joint angles 10-90 degrees and was highest for the VL muscle. VM recruitment efficiency improved more than the VL and RF muscles across 70-90 degrees flexion. The findings demonstrate angle-, and gender-specific responses of knee extensor torque to maximal-effort contractions, while superficial QF muscle recruitment was most efficient at 90 degrees, and less dependent on gender.

  10. Effects of prolonged patellar tendon vibration on force steadiness in quadriceps femoris during force-matching task.

    PubMed

    Saito, Akira; Ando, Ryosuke; Akima, Hiroshi

    2016-01-01

    The quadriceps femoris (QF) muscle group plays an essential role in human movement, such as standing, walking and running. The ability to maintain a steady force during physical activity of the human lower limb is important for mobility, postural control and balance. Although prolonged mechanical vibration of the muscle-tendon unit can moderate the efficacy of synaptic input from Ia afferent onto the α-motor neuron pathway, the effect of prolonged tendon vibration on fluctuations of knee extensor force has received little attention. The purpose of the present study was to examine the effects of prolonged patellar tendon vibration on the force steadiness of the QF muscle. Nine healthy men performed a submaximal force-matching task involving isometric knee extension before and after patellar tendon vibration or quiet seated rest (n = 7, control condition) for 30 min. The target force was 2.5, 10 and 30 % of maximal voluntary contraction (MVC). Surface electromyography (EMG) of the four QF synergists was recorded and normalized to EMG amplitude during the MVC. The knee extension force and the EMG amplitude of vastus medialis during the MVC were significantly reduced after the vibration, but did not significantly decrease in the control condition. Fluctuations of force and normalized EMG of individual QF muscles at each submaximal force level did not significantly change after the vibration. We conclude that prolonged patellar tendon vibration does not influence the force steadiness of the QF muscle during an isometric force-matching task.

  11. Analysis of three different equations for predicting quadriceps femoris muscle strength in patients with COPD *

    PubMed Central

    Nellessen, Aline Gonçalves; Donária, Leila; Hernandes, Nidia Aparecida; Pitta, Fabio

    2015-01-01

    Abstract Objective: To compare equations for predicting peak quadriceps femoris (QF) muscle force; to determine the agreement among the equations in identifying QF muscle weakness in COPD patients; and to assess the differences in characteristics among the groups of patients classified as having or not having QF muscle weakness by each equation. Methods: Fifty-six COPD patients underwent assessment of peak QF muscle force by dynamometry (maximal voluntary isometric contraction of knee extension). Predicted values were calculated with three equations: an age-height-weight-gender equation (Eq-AHWG); an age-weight-gender equation (Eq-AWG); and an age-fat-free mass-gender equation (Eq-AFFMG). Results: Comparison of the percentage of predicted values obtained with the three equations showed that the Eq-AHWG gave higher values than did the Eq-AWG and Eq-AFFMG, with no difference between the last two. The Eq-AHWG showed moderate agreement with the Eq-AWG and Eq-AFFMG, whereas the last two also showed moderate, albeit lower, agreement with each other. In the sample as a whole, QF muscle weakness (< 80% of predicted) was identified by the Eq-AHWG, Eq-AWG, and Eq-AFFMG in 59%, 68%, and 70% of the patients, respectively (p > 0.05). Age, fat-free mass, and body mass index are characteristics that differentiate between patients with and without QF muscle weakness. Conclusions: The three equations were statistically equivalent in classifying COPD patients as having or not having QF muscle weakness. However, the Eq-AHWG gave higher peak force values than did the Eq-AWG and the Eq-AFFMG, as well as showing greater agreement with the other equations. PMID:26398750

  12. Comparison of EMG activity between maximal manual muscle testing and cybex maximal isometric testing of the quadriceps femoris.

    PubMed

    Lin, Hui-Ting; Hsu, Ar-Tyan; Chang, Jia-Hao; Chien, Chi-Sheng; Chang, Guan-Liang

    2008-02-01

    Two methods have been used to produce a maximal voluntary isometric contraction (MVIC) of the superficial quadriceps femoris muscles for normalization of electromyographic (EMG) data. The purposes of this study were to compare the myoelectic activity of MVIC of manual muscle testing (MMT) versus Cybex maximal isometric testing. Eighteen normal subjects were recruited. MMT and Cybex testing for MVIC of the dominant leg were performed. EMG activities of the vastus medialis, vastus lateralis and rectus femoris were recorded during MMT and Cybex trials. EMG amplitude and median frequency obtained from the two methods (MMT and Cybex testing) were used for statistical analysis of these three muscles. Statistically, the difference in the mean of the EMG signal amplitude and median frequency between MMT and Cybex testing were not significant. Considering cost and time, MMT for MVIC technique appears to be reliable and highly valuable.

  13. Effect of eccentric exercise with reduced muscle glycogen on plasma interleukin-6 and neuromuscular responses of musculus quadriceps femoris.

    PubMed

    Gavin, James P; Myers, Stephen D; Willems, Mark E T

    2016-07-01

    Eccentric exercise can result in muscle damage and interleukin-6 (IL-6) secretion. Glycogen availability is a potent stimulator of IL-6 secretion. We examined effects of eccentric exercise in a low-glycogen state on neuromuscular function and plasma IL-6 secretion. Twelve active men (23 ± 4 yr, 179 ± 5 cm, 77 ± 10 kg, means ± SD) completed two downhill treadmill runs (gradient, -12%, 5 × 8 min; speed, 12.1 ± 1.1 km/h) with normal (NG) and reduced muscle glycogen (RG) in randomized order and at least 6 wk apart. Muscle glycogen was reduced using an established cycling protocol until exhaustion and dietary manipulation the evening before the morning run. Physiological responses were measured up to 48 h after the downhill runs. During recovery, force deficits of musculus quadriceps femoris by maximal isometric contractions were similar. Changes in low-frequency fatigue were larger with RG. Voluntary activation and plasma IL-6 levels were similar in recovery between conditions. It is concluded that unaccustomed, damaging eccentric exercise with low muscle glycogen of the m. quadriceps femoris 1) exacerbated low-frequency fatigue but 2) had no additional effect on IL-6 secretion. Neuromuscular impairment after eccentric exercise with low muscle glycogen appears to have a greater peripheral component in early recovery.

  14. Effects of combined application of progressive resistance training and Russian electrical stimulation on quadriceps femoris muscle strength in elderly women with knee osteoarthritis.

    PubMed

    Park, Seong Hoon; Hwangbo, Gak

    2015-03-01

    [Purpose] The aim of this study was to investigate the effects of combined application of progressive resistance training and Russian electrical stimulation on quadriceps femoris muscle strength in elderly women with osteoarthritis of the knee. [Subjects] Thirty women over 65 years of age diagnosed with knee osteoarthritis participated in the present study. The subjects were randomly assigned to a control group (n=10), a progressive resistance training group (n=10), or a Russian electrical stimulation group (n=10). [Methods] Each group was treated 3 times weekly for 8 weeks, and each session lasted 45 minutes. Muscle strength was assessed by measuring the peak torque of the quadriceps femoris muscle. Outcome measurements were performed at baseline and at the fourth and eighth weeks of the treatment period. [Results] All groups showed significant intragroup differences in the quadriceps femoris muscle peak torque after the treatment intervention. There were significant intergroup differences between the Russian electrical stimulation group and the other groups. [Conclusion] The results of this study suggest that combined application of progressive resistance training and Russian electrical stimulation can be effective in strengthening the quadriceps femoris muscle in elderly women with knee osteoarthritis.

  15. How can we strengthen the quadriceps femoris in patients with patellofemoral pain syndrome?

    PubMed Central

    Kaya, Defne; Doral, Mahmut Nedim; Callaghan, Michael

    2012-01-01

    Summary Purpose: the aim of this article was to review the clinical approach of quadriceps strengthening programmes. Methods: a literature search was carried out from 1980 up to September 2011. Eligible studies were those that: (1) evaluated the patients with patellofemoral pain syndrome (not healthy or asymptomatic subjects) (2) examined the effect of kinetic chain exercises (3) examined the effect of weight-bearing exercises (4) compared the effect of the combined exercises programme in the treatment of patients with patellofemoral pain syndrome. Results and conclusion: patients with patellofemoral pain syndrome may tolerate a closed kinetic chain exercises programme better than open kinetic chain. Weight-bearing and non-weight-bearing quadriceps exercises can significantly improve subjective and clinical outcomes in patients with patellofemoral pain syndrome. Combining treatments as an initial approach to treating patellofemoral pain but developing individualized more functional, global treatments are essential. PMID:23738270

  16. Does sensorimotor cortex activity change with quadriceps femoris torque output? A human electroencephalography study.

    PubMed

    Fry, A; Vogt, T; Folland, J P

    2014-09-05

    Encoding muscular force output during voluntary contractions is widely perceived to result, at least in part, from modulations in neuronal activity within the sensorimotor cortex. However the underlying electrophysiological phenomena associated with increased force output remains unclear. This study directly assessed sensorimotor cortex activity using electroencephalography (EEG) in humans performing isometric knee-extensions at a range of discrete torque levels. Fifteen healthy males (age 24 (s=5) years) completed one familiarization and one experimental trial. Participants performed a cyclic series of 60 isometric knee-extension contractions with the right leg, including 15 contractions of a 5-s duration at each of four discrete torque levels: 15%, 30%, 45% and 60% of maximal voluntary torque (MVT). Isometric knee-extension torque, quadriceps electromyography and EEG were recorded at rest and throughout all the contractions. EEG (0.5-50 Hz) was collected using a 32-channel active-electrode cap. A voxel-based low-resolution brain electromagnetic tomography (LORETA) analysis calculated cortical activation within the sensorimotor cortex (one of 27 MNI coordinates) for the entire 0.5-50-Hz range (cortical current density (CCD)), as well as for each constituent frequency band in this range (delta, theta, alpha, beta and gamma). Gamma band (30-50 Hz) cortical activity increased with contraction torque (analysis of variance [ANOVA], P=0.03). Conversely, activity within the other frequency bands was not modulated by torque (P≥0.09), nor was overall CCD (P=0.11). Peripheral neuromuscular activation (quadriceps electromyography (EMG) amplitude) demonstrated distinct increases between each torque level (P<0.01). In conclusion, sensorimotor cortical activity within the gamma band demonstrated an overall increase with contraction torque, whereas both CCD and each of the other constituent frequency bands were not modulated by increments in torque magnitude during isometric

  17. The effect of local skin cooling before a sustained, submaximal isometric contraction on fatigue and isometric quadriceps femoris performance: A randomized controlled trial.

    PubMed

    Hohenauer, Erich; Cescon, Corrado; Deliens, Tom; Clarys, Peter; Clijsen, Ron

    2017-04-01

    The central- and peripheral mechanisms by which heat strain limits physical performance are not fully elucidated. Nevertheless, pre-cooling is often used in an attempt to improve subsequent performance. This study compared the effects of pre-cooling vs. a pre-thermoneutral application on central- and peripheral fatigue during 60% of isometric maximum voluntary contraction (MVC) of the right quadriceps femoris muscle. Furthermore, the effects between a pre-cooling and a pre-thermoneutral application on isometric MVC of the right quadriceps femoris muscle and subjective ratings of perceived exertion (RPE) were investigated. In this randomized controlled trial, 18 healthy adults voluntarily participated. The participants received either a cold (experimental) application (+8°C) or a thermoneutral (control) application (+32°C) for 20min on their right thigh (one cuff). After the application, central (fractal dimension - FD) and peripheral (muscle fiber conduction velocity - CV) fatigue was estimated using sEMG parameters during 60% of isometric MVC. Surface EMG signals were detected from the vastus medialis and lateralis using bidimensional arrays. Immediately after the submaximal contraction, isometric MVC and RPE were assessed. Participants receiving the cold application were able to maintain a 60% isometric MVC significantly longer when compared to the thermoneutral group (mean time: 78 vs. 46s; p=0.04). The thermoneutral application had no significant impact on central fatigue (p>0.05) compared to the cold application (p=0.03). However, signs of peripheral fatigue were significantly higher in the cold group compared to the thermoneutral group (p=0.008). Pre-cooling had no effect on isometric MVC of the right quadriceps muscle and ratings of perceived exertion. Pre-cooling attenuated central fatigue and led to significantly longer submaximal contraction times compared to the pre-thermoneutral application. These findings support the use of pre-cooling procedures

  18. Voluntary activation failure is detectable in some myositis patients with persisting quadriceps femoris weakness: an observational study

    PubMed Central

    Molloy, Catherine B; Al-Omar, Ahmed O; Edge, Kathryn T; Cooper, Robert G

    2006-01-01

    This cross-sectional, observational study was undertaken to examine whether voluntary activation failure could contribute to the persisting weakness observed in some patients with treated idiopathic inflammatory myositis. In 20 patients with myositis of more than six months' duration (5 males, 15 females; mean [± 1 SD] age 53 [11] years) and 102 normal subjects (44 males, 58 females; mean age 32 [8] years), isometric maximum voluntary contractions (MVCs) of the dominant quadriceps femoris (QF) were quantified. Absolute MVC results of normal subjects and patients were then normalised with respect to lean body mass (force per units of lean body mass), giving a result in Newtons per kilogram. Based on mass-normalised force data of normal subjects, patients were arbitrarily stratified into "weak" and "not weak" subgroups. During further MVC attempts, the "twitch interpolation" technique was used to assess whether the QF voluntary activation of patients was complete. This technique relies on the fact that, because muscle activation is incomplete during submaximal voluntary contractions, electrical stimulation of the muscle can induce force increments superimposed on the submaximal voluntary force being generated. No between-gender differences were seen in the mass-normalised MVC results of healthy subjects, so the gender-combined results of 6.6 (1.5) N/kg were used for patient stratification. No between-gender difference was found for mass-normalised MVCs in patients: males 5.4 (3.2) and females 3.0 (1.7) N/kg (p > 0.05). Mass-normalised MVCs of male patients were as great as those of normal subjects (p > 0.05), but mass-normalised MVCs of female patients were significantly smaller than those of the normal subjects (p < 0.001). Only one of the six "not weak" patients exhibited interpolated twitches during electrical stimulation, but six of the 14 "weak" patients did, the biggest twitches being seen in the weakest patient. That interpolated twitches can be induced in

  19. [Amino acid composition of the rat quadriceps femoris muscle after a flight on the Kosmos-936 biosatellite].

    PubMed

    Vlasova, T F; Miroshnikova, E B; Poliakov, V V; Murugova, T P

    1982-01-01

    The amino acid composition of the quadriceps muscle of rats flown onboard the biosatellite Cosmos-936 and exposed to the ground-based synchronous control experiment was studied. The weightless rats showed changes in the amino acid concentration in the quadriceps muscle. The centrifuged flight and synchronous rats displayed an accumulation of free amino acids in the above muscle.

  20. The dependence between clinical condition and value of the maximum force in the quadriceps femoris muscle during MVC test in patients with knee osteoarthritis.

    PubMed

    Nowak, Karina; Sobota, Grzegorz; Bacik, Bogdan; Hajduk, Grzegorz; Kusz, Damian

    2012-01-01

    The aim of this study was to check whether there was a correlation between the value of the maximum developed torque of the quadriceps femoris muscle and subjective evaluation of a patient's pain which is measured by the VAS. Also evaluated were changes in the muscle torque value and KSS scale over time. For examining patient's condition use was made of a KSS scale (knee score: pain, range of motion, stability of joint and limb axis) before the surgery and in weeks 6 and 12, as well as 6 months after surgery. It was found to be constantly improving in comparison with the condition before the surgery. This is confirmed by a significant statistical value difference of KSS scale. The surgery substantially increases the quality of live and function recurrence.

  1. Event-related differences in the cross-sectional areas and torque generation capabilities of quadriceps femoris and hamstrings in male high school athletes.

    PubMed

    Hoshikawa, Yoshihiro; Muramatsu, Masataka; Iida, Tomomi; Uchiyama, Akiko; Nakajima, Yoshiharu; Kanehisa, Hiroaki

    2010-01-01

    This study investigated the event-related differences in the cross-sectional areas (CSAs) and torque generation capabilities of the quadriceps femoris (QF) and hamstrings (HAM) in male high school athletes. Subjects were soccer players (n=32), volleyball players (21), rowers (29), karate athletes (18), sumo wrestlers (15), sprinters (22), throwers (16), and nonathletes (20). The CSAs of QF and HAM at the mid-thigh were determined using magnetic resonance imaging. In addition, isokinetic torques during knee extension and flexion were determined at a pre-set velocity of 1.05 rad/s. The CSAs of the two muscle groups and torques developed in the two motions were significantly related to the two-third power of lean body mass (LBM(2/3)) and the product of CSA and femur length (CSA*fl), calculated as an index of muscle volume, respectively. CSA relative to LBM(2/3) for QF did not differ among the groups, but that for HAM was higher in sprinters, soccer players, throwers, and karate athletes than in sumo wrestlers, rowers, volleyball players, and nonathletes. Knee extension torque relative to the CSA*fl of QF was higher in karate athletes, soccer players, and rowers than in nonathletes, but the corresponding value for knee flexion did not differ among groups. Thus, the present study indicated that, at least in male high school athletes, the event-related differences in LBM and the muscularity of QF and HAM produced the corresponding differences in the CSAs of the reciprocal muscle groups and knee extension and flexion torques, respectively. However, specific profiles related to competitive and/or training styles exist in HAM CSA and knee extension torque, which cannot be explained by the magnitude of LBM and QF CSA, respectively.

  2. Kinesiology Taping does not Modify Electromyographic Activity or Muscle Flexibility of Quadriceps Femoris Muscle: A Randomized, Placebo-Controlled Pilot Study in Healthy Volleyball Players

    PubMed Central

    Halski, Tomasz; Dymarek, Robert; Ptaszkowski, Kuba; Słupska, Lucyna; Rajfur, Katarzyna; Rajfur, Joanna; Pasternok, Małgorzata; Smykla, Agnieszka; Taradaj, Jakub

    2015-01-01

    Background Kinesiology taping (KT) is a popular method of supporting professional athletes during sports activities, traumatic injury prevention, and physiotherapeutic procedures after a wide range of musculoskeletal injuries. The effectiveness of KT in muscle strength and motor units recruitment is still uncertain. The objective of this study was to assess the effect of KT on surface electromyographic (sEMG) activity and muscle flexibility of the rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM) muscles in healthy volleyball players. Material/Methods Twenty-two healthy volleyball players (8 men and 14 women) were included in the study and randomly assigned to 2 comparative groups: “kinesiology taping” (KT; n=12; age: 22.30±1.88 years; BMI: 22.19±4.00 kg/m2) in which KT application over the RF muscle was used, and “placebo taping” (PT; n=10; age: 21.50±2.07 years; BMI: 22.74±2.67 kg/m2) in which adhesive nonelastic tape over the same muscle was used. All subjects were analyzed for resting sEMG activity of the VL and VM muscles, resting and functional sEMG activity of RF muscle, and muscle flexibility of RF muscle. Results No significant differences in muscle flexibility of the RF muscle and sEMG activity of the RF, VL, and VM muscles were registered before and after interventions in both groups, and between the KT and PT groups (p>0.05). Conclusions The results show that application of the KT to the RF muscle is not useful to improve sEMG activity. PMID:26232122

  3. Influence of angular velocity on vastus lateralis and rectus femoris oxygenation dynamics during knee extension exercises.

    PubMed

    Denis, Romain; Wilkinson, Jennifer; De Vito, Giuseppe

    2011-09-01

    The purpose of this study was to investigate whether changes in angular velocity would alter vastus lateralis (VL) and rectus femoris (RF) oxygenation status during maximal isokinetic knee extension exercises. Eleven recreationally active male participants randomly performed ten maximal knee extensions at 30, 60, 120 and 240° s(-1). Tissue oxygenation index (TOI) and total haemoglobin concentration ([tHb]) were acquired from the VL and RF muscles by means of near-infrared spectroscopy (NIRS). Breath-by-breath pulmonary oxygen consumption (VO(2p)) was recorded throughout the tests. Peak torque and VO(2p) significantly decreased as a function of velocity (P<0·05). Interestingly, RF and VL TOI significantly increased as a function of velocity (P<0·05), whereas [tHb] significantly decreased as a function of velocity (P<0·05). A greater number of muscle fibre recruited at slow velocity, where the torque and VO(2p) were the highest, might explain the lower VL and RF TOI observed herein. Furthermore, the increase in local blood flow (suggested by [tHb] changes) during isokinetic knee extension exercises performed at slow angular velocity might have been induced by a higher intramuscular pressure during the contraction phases as well as a greater microcirculatory vasodilatation during relaxation phases. Implementing slow-velocity isokinetic exercises in rehabilitation or other training programmes could delay the short-term anoxia generated by such exercises and result in muscle metabolism enhancement.

  4. Reduced biceps femoris myoelectrical activity influences eccentric knee flexor weakness after repeat sprint running.

    PubMed

    Timmins, R G; Opar, D A; Williams, M D; Schache, A G; Dear, N M; Shield, A J

    2014-08-01

    The aim of this study was to determine whether declines in knee flexor strength following overground repeat sprints were related to changes in hamstrings myoelectrical activity. Seventeen recreationally active men completed maximal isokinetic concentric and eccentric knee flexor strength assessments at 180°/s before and after repeat sprint running. Myoelectrical activity of the biceps femoris (BF) and medial hamstrings (MHs) was measured during all isokinetic contractions. Repeated measures mixed model [fixed factors = time (pre- and post-repeat sprint) and leg (dominant and nondominant), random factor = participants] design was fitted with the restricted maximal likelihood method. Repeat sprint running resulted in significant declines in eccentric, and concentric, knee flexor strength (eccentric = 26 ± 4 Nm, 15% P < 0.001; concentric 11 ± 2 Nm, 10% P < 0.001). Eccentric BF myoelectrical activity was significantly reduced (10%; P = 0.035). Concentric BF and all MH myoelectrical activity were not altered. The declines in maximal eccentric torque were associated with the change in eccentric BF myoelectrical activity (P = 0.013). Following repeat sprint running, there were preferential declines in the myoelectrical activity of the BF, which explained declines in eccentric knee flexor strength.

  5. Musculotendon variability influences tissue strains experienced by the biceps femoris long head muscle during high-speed running.

    PubMed

    Fiorentino, Niccolo M; Blemker, Silvia S

    2014-10-17

    The hamstring muscles frequently suffer injury during high-speed running, though the factors that make an individual more susceptible to injury remain poorly understood. The goals of this study were to measure the musculotendon dimensions of the biceps femoris long head (BFlh) muscle, the hamstring muscle injured most often, and to use computational models to assess the influence of variability in the BFlh's dimensions on internal tissue strains during high-speed running. High-resolution magnetic resonance (MR) images were acquired over the thigh in 12 collegiate athletes, and musculotendon dimensions were measured in the proximal free tendon/aponeurosis, muscle and distal free tendon/aponeurosis. Finite element meshes were generated based on the average, standard deviation and range of BFlh dimensions. Simulation boundary conditions were defined to match muscle activation and musculotendon length change in the BFlh during high-speed running. Muscle and connective tissue dimensions were found to vary between subjects, with a coefficient of variation (CV) of 17±6% across all dimensions. For all simulations peak local strain was highest along the proximal myotendinous junction, which is where injury typically occurs. Model variations showed that peak local tissue strain increased as the proximal aponeurosis width narrowed and the muscle width widened. The aponeurosis width and muscle width variation models showed that the relative dimensions of these structures influence internal muscle tissue strains. The results of this study indicate that a musculotendon unit's architecture influences its strain injury susceptibility during high-speed running.

  6. Influence of extended aging on beef quality characteristics and sensory perception of steaks from the biceps femoris and semimembranosus.

    PubMed

    Colle, M J; Richard, R P; Killinger, K M; Bohlscheid, J C; Gray, A R; Loucks, W I; Day, R N; Cochran, A S; Nasados, J A; Doumit, M E

    2016-09-01

    The objective was to determine the influence of post-fabrication aging (2, 14, 21, 42, and 63days) on beef quality characteristics and consumer sensory perception of biceps femoris (BF) and semimembranosus (SM) steaks. Lipid oxidation and aerobic plate counts increased (P<0.05) with longer aging periods and retail display times. An aging period by day of retail display interaction (P<0.05) was observed for a* and b* values of the BF and SM. Warner-Bratzler shear force values decreased (P<0.05) with longer aging for the SM, while no difference was observed for the BF. Consumer panel results revealed that longer aging periods increased (P<0.05) acceptability of the SM, tenderness of both muscles, and tended to increase (P=0.07) juiciness of the SM. Our results show that extended aging reduces retail color stability yet has positive effects on consumer perception of tenderness of both muscles and overall acceptability of the SM.

  7. Rectus femoris muscle injuries in football: a clinically relevant review of mechanisms of injury, risk factors and preventive strategies.

    PubMed

    Mendiguchia, Jurdan; Alentorn-Geli, Eduard; Idoate, Fernando; Myer, Gregory D

    2013-04-01

    Quadriceps muscle strains frequently occur in sports that require repetitive kicking and sprinting, and are common in football in its different forms around the world. This paper is a review of aetiology, mechanism of injury and the natural history of rectus femoris injury. Investigating the mechanism and risk factors for rectus femoris muscle injury aims to allow the development of a framework for future initiatives to prevent quadriceps injury in football players.

  8. Influence of step rate and quadriceps load distribution on patellofemoral cartilage contact pressures during running.

    PubMed

    Lenhart, Rachel L; Smith, Colin R; Vignos, Michael F; Kaiser, Jarred; Heiderscheit, Bryan C; Thelen, Darryl G

    2015-08-20

    Interventions used to treat patellofemoral pain in runners are often designed to alter patellofemoral mechanics. This study used a computational model to investigate the influence of two interventions, step rate manipulation and quadriceps strengthening, on patellofemoral contact pressures during running. Running mechanics were analyzed using a lower extremity musculoskeletal model that included a knee with six degree-of-freedom tibiofemoral and patellofemoral joints. An elastic foundation model was used to compute articular contact pressures. The lower extremity model was scaled to anthropometric dimensions of 22 healthy adults, who ran on an instrumented treadmill at 90%, 100% and 110% of their preferred step rate. Numerical optimization was then used to predict the muscle forces, secondary tibiofemoral kinematics and all patellofemoral kinematics that would generate the measured primary hip, knee and ankle joint accelerations. Mean and peak patella contact pressures reached 5.0 and 9.7MPa during the midstance phase of running. Increasing step rate by 10% significantly reduced mean contact pressures by 10.4% and contact area by 7.4%, but had small effects on lateral patellar translation and tilt. Enhancing vastus medialis strength did not substantially affect pressure magnitudes or lateral patellar translation, but did shift contact pressure medially toward the patellar median ridge. Thus, the model suggests that step rate tends to primarily modulate the magnitude of contact pressure and contact area, while vastus medialis strengthening has the potential to alter mediolateral pressure locations. These results are relevant to consider in the design of interventions used to prevent or treat patellofemoral pain in runners.

  9. An Acute Bout of Quadriceps Muscle Stretching has no Influence on Knee Joint Proprioception.

    PubMed

    Torres, Rui; Duarte, José Alberto; Cabri, Jan Mh

    2012-10-01

    The main objective of this study was to determine if an acute bout of static stretching of the quadriceps muscle affects the sense of joint position, the threshold to detect passive movement, and the sense of force. Thirty young, healthy men (age : 22.1 ± 2.7 years) were randomly divided into two groups. The Stretching Group (n=15) underwent stretching of the dominant quadriceps muscle, which comprised ten passive stretches lasting 30 seconds each, while the Control Group (n=15) remained seated for the same length of time. A repeated-measures analysis of variance was used to establish intragroup differences over time, and an independent sample t-test was used to compare the dependent variables between groups at each moment. None of the measurements revealed any significant change between both groups in each assessment moment or between moments within groups (p>0.05). This study demonstrated that static quadriceps muscle stretching has no effect on the sense of knee joint position, threshold to detect passive movement, and force sense, suggesting that stretching does not have appreciable effect on the spindle firing characteristics and tendon organs activation.

  10. [Paragliding-associated bilateral partial rupture of the rectus femoris muscle].

    PubMed

    Schulze Bertelsbeck, D; Veelken, D

    2004-12-01

    Pain in the thigh or groin due to a rupture of the rectus femoris muscle is rather uncommon. We report on a patient with a bilateral rupture of the rectus femoris muscle that occurred due to a landing maneuver while para-gliding. The diagnosis was confirmed by ultrasound and MRI. Additionally, an old unilateral anterior cruciate ligament rupture was present. As a functional deficit of the quadriceps muscle could not be observed, a primarily conservative treatment seems to be appropriate.

  11. Quadriceps and Hamstrings Coactivation During Common Therapeutic Exercises

    PubMed Central

    Begalle, Rebecca L.; DiStefano, Lindsay J.; Blackburn, Troy; Padua, Darin A.

    2012-01-01

    Context Anterior tibial shear force and knee valgus moment increase anterior cruciate ligament (ACL) loading. Muscle coactivation of the quadriceps and hamstrings influences anterior tibial shear force and knee valgus moment, thus potentially influencing ACL loading and injury risk. Therefore, identifying exercises that facilitate balanced activation of the quadriceps and hamstrings might be beneficial in ACL injury rehabilitation and prevention. Objective To quantify and compare quadriceps with hamstrings coactivation electromyographic (EMG) ratios during commonly used closed kinetic chain exercises. Design Cross-sectional study. Setting Research laboratory. Patients or Other Participants Twenty-seven healthy, physically active volunteers (12 men, 15 women; age = 22.1 ± 3.1 years, height = 171.4 ± 10 cm, mass = 72.4 ± 16.7 kg). Intervention(s) Participants completed 9 separate closed chain therapeutic exercises in a randomized order. Main Outcome Measure(s) Surface electromyography quantified the activity level of the vastus medialis (VM), vastus lateralis (VL), medial hamstrings (MH), and biceps femoris (BF) muscles. The quadriceps-to-hamstrings (Q:H) coactivation ratio was computed as the sum of average quadriceps (VM, VL) EMG amplitude divided by the sum of average hamstrings (MH, BF) EMG amplitude for each trial. We used repeated-measures analyses of variance to compare Q:H ratios and individual muscle contributions across exercises (α = .05), then used post hoc Tukey analyses. Results We observed a main effect for exercise (F3,79 = 22.6, P < .001). The post hoc Tukey analyses revealed smaller Q:H ratios during the single-limb dead lift (2.87 ± 1.77) than the single-limb squat (5.52 ± 2.89) exercise. The largest Q:H ratios were observed during the transverse-lunge (7.78 ± 5.51, P < .001), lateral-lunge (9.30 ± 5.53, P < .001), and forward-lunge (9.70 ± 5.90, P < .001) exercises. Conclusions The most balanced (smallest) coactivation ratios were

  12. Selective hypertrophy of the quadriceps musculature after 14 weeks of isokinetic and conventional resistance training.

    PubMed

    Matta, Thiago Torres; Nascimento, Francisco Xavier; Trajano, Gabriel S; Simão, Roberto; Willardson, Jeffrey Michael; Oliveira, Liliam Fernandes

    2017-03-01

    One of the fundamental adaptations observed with resistance training (RT) is muscle hypertrophy. Conventional and isokinetic machines provide different forms of mechanical stress, and it is possible that these two training modes could promote differing degrees of hypertrophic adaptations. There is a lack of data comparing the selective hypertrophy of the quadriceps musculature after training with a conventional knee extension machine versus an isokinetic machine. The purpose of this study was to evaluate the selective hypertrophy of the quadriceps musculature and knee extension maximal isometric torque after 14 weeks of conventional versus isokinetic RT. Thirty-five men were assigned to three groups: control group and training groups (conventional and isokinetic) performed three sets of unilateral knee extensions per session with a progressive loading scheme twice a week. Prior to and following the intervention, maximal isometric knee extensor torque was measured using an isokinetic dynamometer, and muscle thickness (MT) of quadriceps femoris muscles was assessed via ultrasound. The results indicated non-uniform changes in MT between the muscles that comprise the quadriceps femoris group. For the conventional group, significantly greater increases in rectus femoris thickness were evident versus all other quadriceps muscles (14%). For the isokinetic group, increases in RF thickness (11%) were significantly greater in comparison with the vastus intermedius only. Although the muscle thickness did not increase for all the quadriceps femoris muscles, the relative rectus femoris adaptation suggested a selective hypertrophy favouring this portion.

  13. Rectus Femoris Tendon Calcification

    PubMed Central

    Zini, Raul; Panascì, Manlio; Papalia, Rocco; Franceschi, Francesco; Vasta, Sebastiano; Denaro, Vincenzo

    2014-01-01

    Background: Since it was developed, hip arthroscopy has become the favored treatment for femoroacetabular impingement. Due to recent considerable improvements, the indications for this technique have been widely extended. Injuries of the rectus femoris tendon origin, after an acute phase, could result in a chronic tendinopathy with calcium hydroxyapatite crystal deposition, leading to pain and loss of function. Traditionally, this condition is addressed by local injection of anesthetic and corticosteroids or, when conservative measures fail, by open excision of the calcific lesion by an anterior approach. Purpose: To assess whether arthroscopic excision of calcification of the proximal rectus is a safe and effective treatment. Study Design: Case series; Level of evidence, 4. Methods: Outcomes were studied from 6 top amateur athletes (age range, 30-43 years; mean, 32.6 years) affected by calcification of the proximal rectus who underwent arthroscopic excision of the calcification. Patients were preoperatively assessed radiographically, and diagnosis was confirmed by a 3-dimensional computed tomography scan. To evaluate the outcome, standardized hip rating scores were used pre- and postoperatively (at 6 and 12 months): the Hip disability and Osteoarthritis Outcome Score, Oxford Hip Score, and Modified Harris Hip Score. Moreover, visual analog scales (VAS) for pain, sport activity level (SAL), and activities of daily living (ADL) were also used. Results: One year after surgery, all patients reported satisfactory outcomes, with 3 of 6 rating their return-to-sport level as high as preinjury level, and the remaining 3 with a percentage higher than 80%. Five patients ranked their ability to carry on daily activities at 100%. Statistical analysis showed significant improvement of the Oxford Hip Score, the Modified Harris Hip Score, and all 3 VAS subscales (pain, SAL, and ADL) from pre- to latest postoperative assessment (P < .05). Conclusion: Arthroscopic excision of

  14. Isokinetic hamstrings-to-quadriceps peak torque ratio: the influence of sport modality, gender, and angular velocity.

    PubMed

    Andrade, Marilia Dos Santos; De Lira, Claudio Andre Barbosa; Koffes, Fabiana De Carvalho; Mascarin, Naryana Cristina; Benedito-Silva, Ana Amélia; Da Silva, Antonio Carlos

    2012-01-01

    The purpose of this study was to determine differences in hamstrings-to-quadriceps (H/Q) peak torque ratios evaluated at different angular velocities between men and women who participate in judo, handball or soccer. A total of 166 athletes, including 58 judokas (26 females and 32 males), 39 handball players (22 females and 17 males), and 69 soccer players (17 females and 52 males), were evaluated using an isokinetic dynamometer. The H/Q isokinetic peak torque ratios were calculated at angular velocities of 1.05 rad · s⁻¹ and 5.23 rad · s⁻¹. In the analysis by gender, female soccer players produced lower H/Q peak torque ratios at 1.05 rad · s⁻¹ than males involved in the same sport. However, when H/Q peak torque ratio was assessed at 5.23 rad · s⁻¹, there were no significant differences between the sexes. In the analysis by sport, there were no differences among females at 1.05 rad · s⁻¹. In contrast, male soccer players had significantly higher H/Q peak torque ratios than judokas (66 ± 12% vs. 57 ± 14%, respectively). Female handball players produced significantly lower peak torque ratios at 5.23 rad · s⁻¹ than judokas or soccer players, whereas males presented no ratio differences among sports At 5.23 rad · s⁻¹. In the analysis by velocity, women's muscular ratios assessed at 1.05 rad · s⁻¹ were significantly lower than at 5.23 rad · s⁻¹ for all sports; among men, only judokas presented lower ratios at 1.05 rad · s⁻¹ than at 5.23 rad · s⁻¹. The present results suggest that sport modality and angular velocity influence the isokinetic strength profiles of men and women.

  15. Clinical anatomy and mechanical tensile properties of the rectus femoris tendon

    PubMed Central

    Zhu, Xing-Fei; Zhang, Xin-Chao

    2015-01-01

    Purpose: We aimed to provide anatomical data and mechanical tensile properties for the rectus femoris tendon to determine if it is a feasible substitute for the anterior cruciate ligament during knee joint reconstruction. Methods: The length and width of the quadriceps femoris tendon were measured from ten adult cadavers (20 knees; age =48±2 years). The anatomic features of the patellar insertion on the quadriceps femoris tendon were also documented. The rectus femoris tendon and anterior cruciate ligament were harvested from an additional five fresh specimens (10 knees; age =41±3 years). To minimize dehydration, each specimen was wrapped in saline-moistened paper towels and stored at -10°C. We imposed tensile stresses on a total of twenty samples in a sample-driven machine at 10 mm/min until the specimens failed. Results: The inserted and discrete widths of the rectus femoris tendon were 3.20±0.33 and 1.28±0.25 cm, respectively. The length of the tendon tissue was 6.96±0.80 cm and the length of mixing zone was 3.81±0.53 cm. The average thickness of the upper pole of the patella was 2.22±0.14 cm. In mechanical tensile properties, the unit modulus and unit maximum load of the rectus femoris tendon were both 63% of the anterior cruciate ligament. Conclusions: Based on its anatomical and mechanical tensile properties, the rectus femoris tendon is a feasible donor site to reconstitute the anterior cruciate ligament. PMID:26885205

  16. Proximal rectus femoris avulsion in an elite, olympic-level sprinter.

    PubMed

    Langer, Phillip R; Selesnick, Harlan

    2010-11-01

    Quadriceps injuries, ranging from simple strains to disabling muscle ruptures, are common athletic injuries. The rectus femoris is the most commonly injure portion of the quadriceps musculature. This article is, to our knowledge, the first report of a proximal rectus femoris avulsion in an elite, Olympic-level 100-meter sprinter, acutely managed with surgical repair. Several key factors must be considered and carefully assessed when determining the appropriate course of management (ie, deciding between operative and nonoperative treatment): amount of distal retraction of the tendon, severity of associated soft-tissue trauma, physical examination, and postoperative goals (eg, return to elite-level competitive sports involving running or kicking vs resuming basic activities of daily living). We believe that these factors in our elite, high-performance athlete dictated an operative course of management.

  17. Continuous Femoral Nerve Blocks: Varying Local Anesthetic Delivery Method (Bolus versus Basal) to Minimize Quadriceps Motor Block while Maintaining Sensory Block

    PubMed Central

    Charous, Matthew T.; Madison, Sarah J.; Suresh, J.; Sandhu, NavParkash S.; Loland, Vanessa J.; Mariano, Edward R.; Donohue, Michael C.; Dutton, Pascual H.; Ferguson, Eliza J.; Ilfeld, Brian M.

    2011-01-01

    Background Whether the method of local anesthetic administration for continuous femoral nerve blocks —basal infusion versus repeated hourly bolus doses —influences block effects remains unknown. Methods Bilateral femoral perineural catheters were inserted in volunteers (n = 11). Ropivacaine 0.1% was administered through both catheters concurrently: a 6-h continuous 5 ml/h basal infusion on one side and 6 hourly bolus doses on the contralateral side. The primary endpoint was the maximum voluntary isometric contraction (MVIC) of the quadriceps femoris muscle at Hour 6. Secondary end points included quadriceps MVIC at other time points, hip adductor MVIC, and cutaneous sensation 2 cm medial to the distal quadriceps tendon in the 22 h following local anesthetic administration initiation. Results Quadriceps MVIC for limbs receiving 0.1% ropivacaine as a basal infusion declined by a mean (SD) of 84% (19) compared with 83% (24) for limbs receiving 0.1% ropivacaine as repeated bolus doses between baseline and Hour 6 (paired t test P = 0.91). Intrasubject comparisons (left vs. right) reflected a lack of difference as well: the mean basal-bolus difference in quadriceps MVIC at Hour 6 was −1.1% (95% CI −22.0 to 19.8%). The similarity did not reach our a priori threshold for concluding equivalence, which was the 95% CI falling within ± 20%. There were similar minimal differences in the secondary endpoints during local anesthetic administration. Conclusions This study did not find evidence to support the hypothesis that varying the method of local anesthetic administration —basal infusion versus repeated bolus doses —influences continuous femoral nerve block effects to a clinically significant degree. PMID:21394001

  18. Surgical Management of Rectus Femoris Avulsion Among Professional Soccer Players

    PubMed Central

    Sonnery-Cottet, Bertrand; Barbosa, Nuno Camelo; Tuteja, Sanesh; Gardon, Roland; Daggett, Matt; Monnot, Damien; Kajetanek, Charles; Thaunat, Mathieu

    2017-01-01

    Background: Rectus femoris injuries are common among athletes, especially in kicking sports such as soccer; however, proximal rectus femoris avulsions in athletes are a relatively rare entity. Purpose/Hypothesis: The purpose of this study was to describe and report the results of an original technique of surgical excision of the proximal tendon remnant followed by a muscular suture repair. Our hypothesis was that this technique limits the risk of recurrence in high-level athletes and allows for rapid recovery without loss of quadriceps strength. Study Design: Case series; Level of evidence, 4. Methods: Our retrospective series included 5 players aged 31.8 ± 3.9 years with acute proximal rectus femoris avulsion injuries who underwent a surgical resection of the proximal tendon between March 2012 and June 2014. Four of these players had recurrent rectus femoris injuries in the 9 months before surgery, while 1 player had surgery after a first injury. Mean follow-up was 18.2 ± 12.6 months, and minimum follow-up was 9 months. We analyzed the age, sex distribution, physical examination outcomes, type and mechanism of injury, diagnosis, treatment and complications during surgery, postoperative follow-up, and time to return to play. The Lower Extremity Functional Scale (LEFS) and Marx scores were obtained at 3-month follow-up, and isokinetic tests were performed before return to sports. A telephone interview was completed to determine the presence of recurrence at an average follow-up of 18.2 months. Results: At 3-month follow-up, all patients had Marx activity scores of 16 and LEFS scores of 80. Return to the previous level of play occurred at a mean of 15.8 ± 2.6 weeks after surgery, and none of the athletes suffered a recurrence. Isokinetic test results were comparable between both sides. Conclusion: The surgical treatment of proximal rectus femoris avulsions, consisting of resection of the tendinous part of the muscle, is a reliable and safe technique allowing a

  19. A dynamic model of quadriceps and hamstrings function.

    PubMed

    Frigo, C; Pavan, E E; Brunner, R

    2010-01-01

    The mechanical effect of hamstrings and quadriceps contractions on hip and knee joint motion was investigated using a dynamic model of the musculoskeletal system. The model consisted of 13 anatomically linked segments. The geometry of bones, joints, and muscle attachments was derived from magnetic resonance imaging of a healthy adult. The knee joint was represented by a crossing bars linkage to simulate cruciate ligament function, and muscles were represented by spring actuators. The effects of hamstring and quadriceps contractions, in various combinations, were tested on different configurations of hip and knee joint position in the absence of gravity. In the standing posture, with the foot free to move and the pelvis fixed in space, the effect of semimembranosus (SM) contraction was hip and knee flexion. If the foot was fixed to the ground, SM contraction produced hip extension and knee flexion. The addition of quadriceps contraction reduced or abolished the knee flexion and enhanced hip extension. In all other simulations, SM alone produced knee flexion and hip extension and the combination of SM with vastus (VA) and rectus femoris (RF) contractions resulted in knee extension and enhanced hip extension. Our findings suggest that co-contraction of quadriceps and hamstrings may be a strategy to increase the hip extension function of the hamstrings.

  20. Atrophy of the quadriceps muscle in children with a painful hip.

    PubMed

    Robben, S G; Lequin, M H; Meradji, M; Diepstraten, A F; Hop, W C

    1999-09-01

    The objective of this study was to determine the degree of muscle wasting of various components of the quadriceps muscle in children with a painful hip. Between January 1994 and September 1997, 327 consecutive children with a unilateral painful hip and/or limping were evaluated prospectively with ultrasonography. Quadriceps thickness was measured on both sides. Moreover, muscle thickness was measured in 59 control subjects. The patients were divided into eight groups; transient synovitis (n = 134), Perthes' disease (n = 35), slipped capital femoral epiphysis (n = 5), osteomyelitis (n = 4), aspecific synovitis (n = 5), rheumatoid arthritis (n = 3) and miscellaneous (n = 16). In 125 patients, no sonographic and radiological abnormalities were found and during follow-up the symptoms disappeared ('no pathology' group). Ipsilateral muscle wasting was present in all patient groups, whereas the control subjects showed no significant difference in muscle thickness between legs. The degree of muscle wasting was compared between transient synovitis, the 'no pathology' group, Perthes' disease and control subjects. For both quadriceps and vastus intermedius muscles, there was a significant difference between these groups, except between control subjects and the 'no pathology' group. For the rectus femoris muscle, there was a significant difference between these groups, except between transient synovitis and 'no pathology'. Muscle wasting showed a positive correlation with duration of symptoms and pre-existing muscle mass. In conclusion, different diseases show different degrees of muscle wasting, and there are different patterns of muscle wasting of various components of the quadriceps femoris muscle.

  1. Quadriceps and hamstrings prelanding myoelectric activity during landing from different heights among male and female athletes.

    PubMed

    de Britto, Morgana Alves; Carpes, Felipe P; Koutras, Georgios; Pappas, Evangelos

    2014-08-01

    ACL tear is a major concern among athletes, coaches and sports scientists. More than taking the athlete away from training and competition, ACL tear is a risk factor for early-onset of knee osteoarthritis, and, therefore addressing strategies to avoid such injury is pertinent not only for competitive athletes, but for all physically active subjects. Imbalances in the prelanding myoelectric activity of the hamstrings and quadriceps muscles have been linked to ACL injuries. We investigated the effect of landing from different heights on prelanding myoelectric activity of the hamstrings and quadriceps muscles in recreational athletes. Thirty recreational athletes (15 male and 15 female) performed three bilateral drop jumps from two different heights; 20cm and 40cm while myoelectric activity of the vastus medialis, rectus femoris, biceps femoris and medial hamstrings were collected. When increasing the height of drop landing tasks prelanding normalized myoelectric activity of the quadriceps was increased by 15-20% but no significant changes were found for the hamstrings. Female athletes exhibited higher activity of the medial hamstrings compared to their male counterparts. We concluded that increasing the height of drop landing tasks is associated with increased myoelectric activity of the quadriceps but not the hamstrings in recreational athletes. These differences in muscle activity may be related to increased risk for ACL injury when the height is increased. Female athletes demonstrated higher recruitment of the medial hamstrings.

  2. Comparison of hamstring-to-quadriceps ratio between accelerating and decelerating sections during squat exercise.

    PubMed

    Yoo, Won-Gyu

    2016-09-01

    [Purpose] The aim of this study was to compare hamstring-to-quadriceps ratio between the accelerating and decelerating sections for anterior cruciate ligament protection during squat exercise. [Subjects and Methods] Nine asymptomatic males were enrolled in this study. The hamstring (medial part) and quadriceps (rectus femoris) muscle activities during squat exercise were measured, and the squat exercises were classified into two sections (accelerating and decelerating) by using an accelerometer. [Results] The hamstring-to-quadriceps ratio was significantly higher in the decelerating section than in the accelerating section during the squat exercise. [Conclusion] Application of an increasing decelerating section strategy during the squat exercise can prevent damage in patients with a weakened anterior cruciate ligament due to sports activities.

  3. Reliability of surface EMG during sustained contractions of the quadriceps.

    PubMed

    Mathur, S; Eng, J J; MacIntyre, D L

    2005-02-01

    The purpose of this study was to determine test-retest reliability for median frequency (MDF) and amplitude of surface EMG during sustained fatiguing contractions of the quadriceps. Twenty-two healthy subjects (11 males and 11 females) were tested on two days held one week apart. Surface EMG was recorded from rectus femoris (RF), vastus lateralis (VL) and vastus medialis (VM) during sustained isometric contractions at 80% and 20% of maximal voluntary contraction (MVC) held to exhaustion. Quadriceps fatigue was described using four measures for both MDF and amplitude of EMG: initial, final, normalized final and slope. For both MDF and amplitude, the initial, final and normalized EMG showed moderate to high reliability for all three muscle groups at both contraction levels (ICC=0.59-0.88 for MDF; ICC=0.58-0.99 for amplitude). Slope of MDF and amplitude was associated with a large degree of variability and low ICCs for the 80% but not the 20% MVC. MDF and amplitude of EMG during sustained contractions of the quadriceps are reproducible; normalized final values of MDF and amplitude show better reliability than slope.

  4. Recruitment of fibre types and quadriceps muscle portions during repeated, intense knee-extensor exercise in humans.

    PubMed

    Krustrup, Peter; Söderlund, Karin; Mohr, Magni; González-Alonso, José; Bangsbo, Jens

    2004-10-01

    To investigate recruitment of slow-twitch (ST) and fast-twitch (FT) muscle fibres, as well as the involvement of the various quadriceps femoris muscle portions during repeated, intense, one-legged knee-extensor exercise, 12 healthy male subjects performed two 3-min exercise bouts at approximately 110% maximum thigh O2 consumption (EX1 and EX2) separated by 6 min rest. Single-fibre metabolites were determined in successive muscle biopsies obtained from the vastus lateralis muscle (n = 6) and intra-muscular temperatures were continuously measured at six quadriceps muscle sites (n = 6). Creatine phosphate (CP) had decreased (P < 0.05) by 27, 73 and 88% in ST fibres and 25, 71 and 89% in FT fibres after 15 and 180 s of EX1 and after 180 s of EX2, respectively. CP was below resting mean-1 SD in 15, 46, 84 and 100% of the ST fibres and 9, 48, 85 and 100% of the FT fibres at rest, after 15 and 180 s of EX1 and after 180 s of EX2, respectively. A significant muscle temperature increase (deltaTm) occurred within 2-4 s at all quadriceps muscle sites. DeltaTm varied less than 10% between sites during EX1, but was 23% higher (P < 0.05) in the vastus lateralis than in the rectus femoris muscle during EX2. DeltaTm in the vastus lateralis was 101 and 109% of the mean quadriceps value during EX1 and EX2, respectively. We conclude that both fibre types and all quadriceps muscle portions are recruited at the onset of intense knee-extensor exercise, that essentially all quadriceps muscle fibres are activated during repeated intense exercise and that metabolic measurements in the vastus lateralis muscle provide a good indication of the whole-quadriceps muscle metabolism during repeated, intense, one-legged knee-extensor exercise.

  5. Quadriceps muscle strength in scoliosis.

    PubMed

    Swallow, E B; Barreiro, E; Gosker, H; Sathyapala, S A; Sanchez, F; Hopkinson, N S; Moxham, J; Schols, A; Gea, J; Polkey, M I

    2009-12-01

    Quadriceps muscle weakness is an important component of chronic obstructive pulmonary disease (COPD). We hypothesised that quadriceps weakness would also be a feature of restrictive lung disease due to scoliosis. We studied 10 patients with severe scoliosis (median (interquartile range (IQR)) forced expiratory volume in 1 s (FEV(1))() 35.3 (11)% predicted), 10 patients with severe COPD (FEV(1) 26.5 (9.0)% pred) and 10 healthy age-matched adults. We measured quadriceps strength, exercise capacity and analysed quadriceps muscle biopsies for myosin heavy-chain (MyHC) isoform expression and the presence of oxidative stress. Both groups exhibited quadriceps weakness with median (IQR) maximal voluntary contraction force being 46.0 (17.0) kg, 21.5 (21.0) kg and 31.5 (11.0) kg, respectively (p = 0.02 and 0.04, respectively, for each patient group against controls). Oxidative stress was significantly greater in the quadriceps of both restrictive and COPD patients. The scoliosis patients exhibited a decrease in the proportion of MyHC type I compared with controls; median (IQR) 35.3 (18.5)% compared with 47.7 (9.3)%, p = 0.028. The scoliosis patients also showed an increase in MyHC IIx (26.3 (15.5)% compared with 11.3 (13.0)%, p = 0.01. Quadriceps weakness is a feature of severe scoliosis; the similarities between patients with scoliosis and patients with COPD suggest a common aetiology to quadriceps weakness in both conditions.

  6. Distal Insertions of the Biceps Femoris

    PubMed Central

    Branch, Eric A.; Anz, Adam W.

    2015-01-01

    Background: Avulsion of the biceps femoris from the fibula and proximal tibia is encountered in clinical practice. While the anatomy of the primary posterolateral corner structures has been qualitatively and quantitatively described, a quantitative analysis regarding the insertions of the biceps femoris on the fibula and proximal tibia is lacking. Purpose: To quantitatively assess the insertions of the biceps femoris, fibular collateral ligament (FCL), and anterolateral ligament (ALL) on the fibula and proximal tibia as well as establish relationships among these structures and to pertinent surgical anatomy. Study Design: Descriptive laboratory study. Methods: Dissections were performed on 12 nonpaired, fresh-frozen cadaveric specimens identifying the biceps femoris, FCL, and ALL, and their insertions on the proximal tibia and fibula. The footprint areas, orientations, and distances from relevant osseous landmarks were measured using a 3-dimensional coordinate measurement device. Results: Dissection produced 6 easily identifiable and reproducible anatomic footprints. Tibial footprints included the insertion of the ALL and an insertion of the biceps femoris (TBF). Fibular footprints included the insertion of the FCL, a distal insertion of the biceps femoris (DBF), a medial footprint of the biceps femoris (MBF), and a proximal footprint of the biceps femoris (PBF). The mean area of these footprints (95% CI) was as follows: ALL, 53.0 mm2 (38.4-67.6); TBF, 93.9 mm2 (72.0-115.8); FCL, 86.8 mm2 (72.3-101.2); DBF, 119 mm2 (91.1-146.9); MBF, 46.8 mm2 (29.0-64.5); and PBF, 215 mm2 (192.4-237.5). The mean distance (95% CI) from the Gerdy tubercle to the center of the ALL footprint was 24.3 mm (21.6-27.0) and to the center of the TBF was 22.5 mm (21.0-24.0). The center of the DBF was 8.68 mm (7.0-10.3) from the anterior border of the fibula, the center of the FCL was 14.6 mm (12.5-16.7) from the anterior border of the fibula and 20.7 mm (19.0-22.4) from the tip of the fibular

  7. Contribution of Hamstring Fatigue to Quadriceps Inhibition Following Lumbar Extension Exercise

    PubMed Central

    Hart, Joseph M.; Kerrigan, D. Casey; Fritz, Julie M.; Saliba, Ethan N.; Gansneder, Bruce; Ingersoll, Christopher D.

    2006-01-01

    The purpose of this study was to determine the contribution of hamstrings and quadriceps fatigue to quadriceps inhibition following lumbar extension exercise. Regression models were calculated consisting of the outcome variable: quadriceps inhibition and predictor variables: change in EMG median frequency in the quadriceps and hamstrings during lumbar fatiguing exercise. Twenty-five subjects with a history of low back pain were matched by gender, height and mass to 25 healthy controls. Subjects performed two sets of fatiguing isometric lumbar extension exercise until mild (set 1) and moderate (set 2) fatigue of the lumbar paraspinals. Quadriceps and hamstring EMG median frequency were measured while subjects performed fatiguing exercise. A burst of electrical stimuli was superimposed while subjects performed an isometric maximal quadriceps contraction to estimate quadriceps inhibition after each exercise set. Results indicate the change in hamstring median frequency explained variance in quadriceps inhibition following the exercise sets in the history of low back pain group only. Change in quadriceps median frequency explained variance in quadriceps inhibition following the first exercise set in the control group only. In conclusion, persons with a history of low back pain whose quadriceps become inhibited following lumbar paraspinal exercise may be adapting to the fatigue by using their hamstring muscles more than controls. Key Points A neuromuscular relationship between the lumbar paraspinals and quadriceps while performing lumbar extension exercise may be influenced by hamstring muscle fatigue. QI following lumbar extension exercise in persons with a history of LBP group may involve significant contribution from the hamstring muscle group. More hamstring muscle contribution may be a necessary adaptation in the history of LBP group due to weaker and more fatigable lumbar extensors. PMID:24198683

  8. Neuromuscular performance of maximal voluntary explosive concentric contractions is influenced by angular acceleration.

    PubMed

    Hahn, D; Bakenecker, P; Zinke, F

    2016-12-28

    Torque production during maximal voluntary explosive contractions is considered to be a functionally more relevant neuromuscular measure than steady-state torque, but little is known about accelerated concentric contractions. This study investigated torque, muscle activity, and fascicle behavior during isometric and fast concentric contractions of quadriceps femoris. Ten participants performed maximal voluntary explosive isometric, isovelocity, and additional concentric knee extensions at angular accelerations ranging from 700 to 4000° s(-2) that resulted in an angular velocity of 300° s(-1) at 40° knee flexion. Concentric torque at 40° knee flexion was corrected for inertia, and the corresponding isometric torque was matched to the time when the target knee angle of 40° was reached during concentric contractions. Electromyography of quadriceps femoris and hamstrings and ultrasound of vastus lateralis were measured to determine muscle activity, fascicle length, and fascicle velocity (FV). The faster the acceleration, the more torque was produced during concentric contractions at 40° knee flexion, which was accompanied by a reduction in FV. In comparison with isometric conditions, concentric quadriceps muscle activity was increased and torque during accelerations ≥3000° s(-2) equaled the time-matched isometric torque. Our results provide novel evidence that acceleration influences torque production during maximal voluntary explosive concentric contractions. This is suggested to be due to series elasticity and reduced force depression.

  9. Increase in passive muscle tension of the quadriceps muscle heads in jumping athletes with patellar tendinopathy.

    PubMed

    Zhang, Z J; Ng, G Y F; Lee, W C; Fu, S N

    2016-08-19

    To investigate the passive muscle tension of the quadriceps muscle heads in male athletes clinically diagnosed with patellar tendinopathy (PT) with those of healthy controls and explore the interplay between passive muscle tension and patellar tendon stiffness. Between November 2012 and December 2013, 66 male athletes (mean age of 21.1 ± 4.4 years) were examined using supersonic shear wave imaging technology. The passive tension of the vastus lateralis (VL) and rectus femoris (RF) muscles and patellar tendon stiffness were assessed. The shear elastic modulus of the VL muscle was increased by 26.5% (P < 0.001) in the subjects with PT when compared with the controls. Greater passive tension in the VL was associated with higher patellar tendon stiffness (r = 0.38; P = 0.001). The vastus lateralis muscle of the quadriceps shows increase in passive muscle tension in jumping athletes with patellar tendinopathy. These findings suggest that increase in muscle tension is not similar in the individual muscles of the quadriceps muscle. Traditional stretching of the whole quadriceps muscle might not be targeted to the tight muscle heads.

  10. Pre-freezing raw hams affects quality traits in cooked hams: potential influence of protein oxidation.

    PubMed

    Utrera, M; Armenteros, M; Ventanas, S; Solano, F; Estévez, M

    2012-12-01

    The influence of protein carbonylation and lipid oxidation on colour and texture changes in cooked hams from fresh and pre-frozen (frozen/thawed) raw material was studied. Samples from three muscles, biceps femoris (BF) quadriceps femoris (QF) and semimembranosus (SM) were analysed for the gain of specific protein carbonyls, α-aminoadipic and γ-glutamic semialdehydes, the gain of TBA-RS and their colour and texture properties by instrumental and sensory techniques. The formation of protein carbonyls occurred concomitantly with an intense loss of redness and increase of hardness. Both phenomena were found to be more intense in QF and SM muscles in cooked hams elaborated from frozen material. Lipid oxidation played a negligible role on the impaired quality traits observed in cooked hams as a result of pre-freezing. Plausible mechanisms by which protein carbonylation may be implicated in the loss of quality in cooked hams produced from pre-frozen material are discussed.

  11. Differential Glucose Uptake in Quadriceps and Other Leg Muscles During One-Legged Dynamic Submaximal Knee-Extension Exercise

    PubMed Central

    Kalliokoski, Kari K.; Boushel, Robert; Langberg, Henning; Scheede-Bergdahl, Celena; Ryberg, Ann Kathrine; Døssing, Simon; Kjær, Andreas; Kjær, Michael

    2011-01-01

    One-legged dynamic knee-extension exercise (DKE) is a widely used model to study the local cardiovascular and metabolic responses to exercise of the quadriceps muscles. In this study, we explored the extent to which different muscles of the quadriceps are activated during exercise using positron emission tomography (PET) determined uptake of [18F]-fluoro-deoxy-glucose (GU) during DKE. Five healthy male subjects performed DKE at 25 W for 35 min and both the contracting and contralateral resting leg were scanned with PET from mid-thigh and distally. On average, exercise GU was the highest in the vastus intermedius (VI) and lowest in the vastus lateralis (VL; VI vs VL, p < 0.05), whereas the coefficient of variation was highest in VL (VL vs VI, p < 0.05). Coefficient of variation between the mean values of the four quadriceps femoris (QF) muscles in the exercising leg was 35 ± 9%. Compared to mean GU in QF (=100%), GU was on average 73% in VL, 84% in rectus femoris, 115% in vastus medialis, and 142% in VI. Variable activation of hamstring muscles and muscles of the lower leg was also observed. These results show that GU of different muscles of quadriceps muscle group as well as between individuals vary greatly during DKE, and suggests that muscle activity is not equal between quadriceps muscles in this exercise model. Furthermore, posterior thigh muscles and lower leg muscles are more active than hitherto thought even during this moderate exercise intensity. PMID:22046164

  12. Bedside Ultrasound Measurement of Rectus Femoris: A Tutorial for the Nutrition Support Clinician

    PubMed Central

    Monares Zepeda, Enrique; Lescas Méndez, Octavio Augusto

    2017-01-01

    Intensive care unit acquired weakness is a long-term consequence after critical illness; it has been related to muscle atrophy and can be considered as one of the main nutritional support challenges at the intensive care unit. Measuring muscle mass by image techniques has become a new area of research for the nutritional support field, extending our knowledge about muscle wasting and the impact of nutritional approaches in the critical care setting, although currently there is no universally accepted technique to perform muscle measurements by ultrasound. Because of this, we present this tutorial for nutrition support clinicians, in order to understand and perform muscle measurements by this reliable, accessible, low-cost, and easy-to-use technique. Reviewing issues such as quadriceps muscle anatomy, correct technique (do's and don'ts), identification of structures, and measurement of the rectus femoris and vastus intermedius muscles helps to acquire the basic concepts of this technique and encouraging more research in this field. PMID:28386479

  13. Static vs. Dynamic Acute Stretching Effect on Quadriceps Muscle Activity during Soccer Instep Kicking

    PubMed Central

    Amiri-Khorasani, Mohammadtaghi; Kellis, Eleftherios

    2013-01-01

    The purpose of this study was to compare the effects of static and dynamic stretching on quadriceps muscle activation during maximal soccer instep kicking. The kicking motion of twelve male college soccer players (body height: 174.66 ± 5.01 cm; body mass: 72.83 ± 4.83 kg; age: 18.83 ± 0.75 years) was captured using six synchronized high-speed infra-red cameras whilst electromyography (EMG) signals from vastus medialis (VM), lateralis (VL) and rectus femoris (RF) were recorded before and after static or dynamic stretching. Analysis of variance designs showed a higher increase in knee extension angular velocity (9.65% vs. −1.45%, p < 0.001), RF (37.5% vs. −8.33%, p < 0.001), VM (12% vs. −12%, p < 0.018), and VL EMG activity (20% vs. −6.67%, p < 0.001) after dynamic stretching exercises. Based on these results, it could be suggested that dynamic stretching is probably more effective in increasing quadriceps muscle activity and knee extension angular velocity during the final swing phase of a maximal soccer instep kick than static stretching. PMID:24511339

  14. ‘Serious thigh muscle strains’: beware the intramuscular tendon which plays an important role in difficult hamstring and quadriceps muscle strains

    PubMed Central

    Brukner, Peter; Connell, David

    2016-01-01

    Why do some hamstring and quadriceps strains take much longer to repair than others? Which injuries are more prone to recurrence? Intramuscular tendon injuries have received little attention as an element in ‘muscle strain’. In thigh muscles, such as rectus femoris and biceps femoris, the attached tendon extends for a significant distance within the muscle belly. While the pathology of most muscle injures occurs at a musculotendinous junction, at first glance the athlete appears to report pain within a muscle belly. In addition to the musculotendinous injury being a site of pathology, the intramuscular tendon itself is occasionally injured. These injuries have a variety of appearances on MRIs. There is some evidence that these injuries require a prolonged rehabilitation time and may have higher recurrence rates. Therefore, it is important to recognise the tendon component of a thigh ‘muscle strain’. PMID:26519522

  15. Proximal Rectus Femoris Avulsion: Ultrasonic Diagnosis and Nonoperative Management

    PubMed Central

    Esser, Stephan; Jantz, David; Hurdle, Mark F.; Taylor, Walter

    2015-01-01

    Objective To present a case of ultrasonic diagnosis and nonoperative management of a complete proximal rectus femoris avulsion in a National Collegiate Athletic Association Division 1 soccer goalkeeper. Background While delivering a goal kick, a previously uninjured 24-year-old collegiate soccer goalkeeper had the sudden onset of right anterior thigh pain. He underwent rehabilitation with rapid resolution of his presenting pain but frequent intermittent recurrence of anterior thigh pain. After he was provided a definitive diagnosis with musculoskeletal ultrasound, he underwent an extended period of rehabilitation and eventually experienced complete recovery without recurrence. Differential Diagnosis Rectus femoris avulsion, rectus femoris strain or partial tear, inguinal hernia, or acetabular labral tear. Treatment Operative and nonoperative options were discussed. In view of the player's recovery, nonoperative options were pursued with a good result. Uniqueness Complete proximal rectus femoris avulsions are rare. Our case contributes to the debate on whether elite-level kicking and running athletes can return to full on-field performance without surgery. Conclusions Complete proximal rectus femoris avulsions can be treated effectively using nonoperative measures with good preservation of function even in the elite-level athlete. In addition, musculoskeletal ultrasound is an excellent tool for on-site evaluation and may help guide prognosis and management. PMID:25978099

  16. Effects of Exposure to Normobaric Hyperoxia on the Recovery of Local Muscle Fatigue in the Quadriceps Femoris of Young People

    PubMed Central

    Yokoi, Yuka; Yanagihashi, Ryuya; Morishita, Katsuyuki; Fujiwara, Takayuki; Abe, Koji

    2014-01-01

    [Purpose] Acute development of local muscle fatigue and recovery often become large issues on sports fields. This study aimed to identify the effects of normobaric hyperoxia on the recovery of local muscle fatigue. [Subjects] Eleven healthy males participated in this study, and they all completed two protocols in a random order. [Methods] Subjects performed single-leg isometric knee extension at 70% of their maximum voluntary isometric contraction (MVIC) for as long as possible. Each participant was subsequently treated with one of two recovery conditions: 20.9% O2 or 30.0% O2 for 30 minutes. Afterwards, they performed an identical isometric task to measure the extent of their recovery. The following parameters were used to assess the degrees of muscle fatigue: MVIC, endurance time, surface electromyography (sEMG) power spectra, and changes in hemoglobin concentration using near-infrared spectroscopy (NIRS). [Results] The treatment of 30.0% O2 induced a significant recovery rate in MVIC compared to the 20.9% O2. Additionally, the data revealed a significantly higher concentration of total hemoglobin after the 30.0% O2 treatment than after the 20.9% O2 treatment. [Conclusion] The results of this study suggest that recovery from acute muscle fatigue can be better facilitated under 30.0% normobaric hyperoxia than a normoxic condition. Therefore, for cases requiring quicker full recovery, treatment under 30.0% O2 environment for 30 minutes is recommended. PMID:24707107

  17. Muscle deoxygenation in the quadriceps during ramp incremental cycling: Deep vs. superficial heterogeneity.

    PubMed

    Okushima, Dai; Poole, David C; Rossiter, Harry B; Barstow, Thomas J; Kondo, Narihiko; Ohmae, Etsuko; Koga, Shunsaku

    2015-12-01

    Muscle deoxygenation (i.e., deoxy[Hb + Mb]) during exercise assesses the matching of oxygen delivery (Q̇O2) to oxygen utilization (V̇O2). Until now limitations in near-infrared spectroscopy (NIRS) technology did not permit discrimination of deoxy[Hb + Mb] between superficial and deep muscles. In humans, the deep quadriceps is more highly vascularized and oxidative than the superficial quadriceps. Using high-power time-resolved NIRS, we tested the hypothesis that deoxygenation of the deep quadriceps would be less than in superficial muscle during incremental cycling exercise in eight males. Pulmonary V̇O2 was measured and muscle deoxy[Hb + Mb] was determined in the superficial vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF-s) and the deep rectus femoris (RF-d). deoxy[Hb + Mb] in RF-d was significantly less than VL at 70% (67.2 ± 7.0 vs. 75.5 ± 10.7 μM) and 80% (71.4 ± 11.0 vs. 79.0 ± 15.4 μM) of peak work rate (WR(peak)), but greater than VL and VM at WR(peak) (87.7 ± 32.5 vs. 76.6 ± 17.5 and 75.1 ± 19.9 μM). RF-s was intermediate at WR(peak) (82.6 ± 18.7 μM). Total hemoglobin and myoglobin concentration and tissue oxygen saturation were significantly greater in RF-d than RF-s throughout exercise. The slope of deoxy[Hb + Mb] increase (proportional to Q̇O2/V̇O2) in VL and VM slowed markedly above 70% WR(peak), whereas it became greater in RF-d. This divergent deoxygenation pattern may be due to a greater population of slow-twitch muscle fibers in the RF-d muscle and the differential recruitment profiles and vascular and metabolic control properties of specific fiber populations within superficial and deeper muscle regions.

  18. Quadriceps Muscle Mechanical Simulator for Training of Vastus Medialis Obliquus and Vastus Lateralis Obliquus Mechanical Properties

    PubMed Central

    Irmak, Rafet; Irmak, Ahsen; Biçer, Gökhan

    2014-01-01

    Objectives: In classical anatomy quadriceps muscle has four heads. Clinical studies have demostrated 6 heads of this muscle. These heads were demostrated seperately not only by their functional properties,but also by innervation and kinesiological properties. In our previous study we have developed and demostrated electrophysiological properties of vastus medialis obliquus by an electronic patient simulator. The purpose of this study is to develop a mechanical simulator which can be used to demostrate mechanical properties of 6 heads of quadriceps muscle and the screw home mechanism. Methods: Quadriceps femoris muscle has 6 heads: rectus femoris, vastus intermedius, vastus medialis obliquus, vastus medialis longus, vastus lateralis obliquus and vastus lateralis longus. The fundamental mechanical properties of each head is seperated by insersio and angle of pull. Main design principle was to demostrate all heads with insersio and angle of pull properties. Second design principle was to demostrate the screw-home mechanism which is the result of difference in articular surfaces of medial and lateral of condyles of femur. Results: Final design of the simulator consists of three planes for demostration of angle of pull and pulling forces (patellar plane, proximal and distal planes) of each heads. On each plane channels were graved as origo and insersio for demostration of angle of pull. Distal plane was movable for demostration of pulling forces in different angels of knee flexion and extention. Also proximal plane was adjustable to demostrate different sitting and standing positions. Srew home mechanism was demostrated by specially designed hingle mechanism. Left and right side hingle mechanisms have different radii as femoral condyles and this difference can cause rotation in terminal extension as in the screw home mechanism. Conclusion: Vastus medialis obliquus, vastus lateralis obliquus and screw-home mechanism have clinical significance. We were not able to find

  19. Isokinetic Hamstrings: Quadriceps Ratios in Intercollegiate Athletes.

    ERIC Educational Resources Information Center

    Rosene, John M.; Fogarty, Tracey D.; Mahaffey, Brian L.

    2001-01-01

    Compared the differences in the concentric hamstrings to quadriceps (H:Q) ratio among athletes in different sports at three velocities. Measurement of H:Q ratio of both knees among male and female college athletes indicated that the H:Q ratio increased as velocity increased. No differences existed for the H:Q ratio for sport or side of body. (SM)

  20. Heterogeneous recruitment of quadriceps muscle portions and fibre types during moderate intensity knee-extensor exercise: effect of thigh occlusion.

    PubMed

    Krustrup, P; Söderlund, K; Relu, M U; Ferguson, R A; Bangsbo, J

    2009-08-01

    The involvement of quadriceps femoris muscle portions and fibre type recruitment was studied during submaximal knee-extensor exercise without and with thigh occlusion (OCC) and compared with responses during intense exercise. Six healthy male subjects performed 90-s of moderate exercise without (MOD; 29+/-4 W) and with thigh OCC, and moderate exercise followed by 90-s of intense exercise (HI; 65+/-8 W). Temperatures were continuously measured in m. vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) and successive muscle biopsies were obtained from VL. During MOD, muscle temperature increase (DeltaT(m)) in RF was 0.52+/-0.09 degrees C, which was 57% and 73% higher (P<0.05) than in VL and VM, respectively. During OCC, DeltaT(m) in RF was 0.39+/-0.05 degrees C, which was not different from VM but 54% higher (P<0.05) than in VL. After MOD, muscle CP in slow twitch (ST) and fast twitch (FT) fibres was 81% and 91% of resting levels, respectively, with lower (P<0.05) values after OCC (15% and 22%) and HI (24% and 13%). After MOD, OCC and HI, a total of 48%, 93% and 96% of the ST fibres had CP levels below mean-1 SD, respectively, with corresponding values for FT fibres being 41%, 89% and 100%, respectively. In conclusion, a heterogeneous recruitment of the quadriceps muscle portions and muscle fibres was observed during submaximal knee-extensor exercise, whereas recruitment pattern was homogenous during intense exercise. Thigh OCC caused an altered recruitment of fibres and muscle portions, suggesting a significant afferent response affecting the activation of fibres in the contracting muscles.

  1. Acute Calcific Tendinitis of the Rectus Femoris: A Case Series

    PubMed Central

    Kobayashi, Hideo; Kaneko, Haruka; Homma, Yasuhiro; Baba, Tomonori; Kaneko, Kazuo

    2015-01-01

    Introduction: Periarticular calcific tendinitis is a common cause of Orthopedic outpatient referral. Calcific tendinitis of the rectus femoris, however, is very rare and not well known. Due to its rarity, correct diagnosis and prompt treatment are not fully understood. Case Report: Two females (38 and 40 years old) of acute calcific tendinitis of the rectus femoris with the good clinical course without any operative treatment were presented. The pain was managed with oral non-steroidal antiinflammatory drugs and/or local steroid injection. Interval radiographic assessment showed complete resorption of the calcification. Conclusion: Establishing the correct diagnosis and initiating prompt treatment are shown to be important in achieving resolution of symptoms and in avoiding unnecessary investigations. PMID:27299063

  2. Endovascular Repair of a Large Profunda Femoris Artery Pseudoaneurysm

    PubMed Central

    Khalid, Ahsan Syed; Ghanem, Omar M.; Mojtaba Gashti, Seyed

    2014-01-01

    Profunda femoris artery aneurysms and pseudoaneurysms are a rare cause of peripheral arterial aneurysms but their risk of rupture is quite high. We have presented a case of a left lower leg pseudoaneurysm. We have shown that endovascular repair with angioplasty and stenting is a suitable treatment method for such a pseudoaneurysm. Due to the limited data on this disease, we suggest multi-institute collaboration to identify and standardize management for the treatment. PMID:24716098

  3. Transcranial Magnetic Stimulation and Volitional Quadriceps Activation

    PubMed Central

    Gibbons, Christopher E.; Pietrosimone, Brian G.; Hart, Joseph M.; Saliba, Susan A.; Ingersoll, Christopher D.

    2010-01-01

    Abstract Context: Quadriceps-activation deficits have been reported after meniscectomy. Transcranial magnetic stimulation (TMS) in conjunction with maximal contractions affects quadriceps activation in patients after meniscectomy. Objective: To determine the effect of single-pulsed TMS on quadriceps central activation ratio (CAR) in patients after meniscectomy. Design: Randomized controlled clinical trial. Setting: University laboratory. Patients or Other Participants: Twenty participants who had partial meniscectomy and who had a CAR less than 85% were assigned randomly to the TMS group (7 men, 4 women; age  =  38.1 ± 16.2 years, height  =  176.8 ± 11.5 cm, mass  =  91.8 ± 27.5 kg, postoperative time  =  36.7 ± 34.9 weeks) or the control group (7 men, 2 women; age  =  38.2 ± 17.5 years, height  =  176.5 ± 7.9 cm, mass  =  86.2 ± 15.3 kg, postoperative time  =  36.6 ± 37.4 weeks). Intervention(s): Participants in the experimental group received TMS over the motor cortex that was contralateral to the involved leg and performed 3 maximal quadriceps contractions with the involved leg. The control group performed 3 maximal quadriceps contractions without the TMS. Main Outcome Measure(s): Quadriceps activation was assessed using the CAR, which was measured in 70° of knee flexion at baseline and at 0, 10, 30, and 60 minutes posttest. The CAR was expressed as a percentage of full activation. Results: Differences in CAR were detected over time (F4,72  =  3.025, P  = .02). No interaction (F4,72  =  1.457, P  =  .22) or between-groups differences (F1,18  =  0.096, P  =  .76) were found for CAR. Moderate CAR effect sizes were found at 10 (Cohen d  =  0.54, 95% confidence interval [CI]  =  −0.33, 1.37) and 60 (Cohen d  =  0.50, 95% CI  =  −0.37, 1.33) minutes in the TMS group compared with CAR at baseline. Strong effect sizes were found for CAR at 10 (Cohen d  =  0.82, 95% CI

  4. Differences in twitch potentiation between voluntary and stimulated quadriceps contractions of equal intensity.

    PubMed

    Jubeau, M; Gondin, J; Martin, A; Van Hoecke, J; Maffiuletti, N A

    2010-02-01

    This study compared the extent of twitch and M-wave potentiation (POT) between voluntary and stimulated quadriceps contractions performed at the same intensity. Sixteen healthy men completed 10-s isometric knee extensions at 40% of the maximal voluntary contraction torque under electrical stimulation and voluntary conditions. Single stimuli were delivered to the femoral nerve to evoke twitches before (PRE) and from 3 to 600 s after the end of each conditioning contraction. Changes in twitch contractile properties and M-wave characteristics were compared between the conditions. The extent of twitch peak torque POT was smaller for the stimulated (122+/-20% of PRE) than for the voluntary condition (133+/-20% of PRE). The magnitude of POT for the maximal rate of twitch torque development was also smaller for the stimulated trial. Rectus femoris M-wave amplitude was potentiated by the voluntary but not by the stimulated contraction. It was concluded that stimulated contractions resulted in smaller twitch and M-wave POT than voluntary contractions, despite equivalent torque output and duration. The spatially and temporally fixed recruitment of motor units with electrical stimulation and therefore the lower number of activated motor units compared with voluntary actions of equal intensity could explain the present findings.

  5. Dynamic in vivo quadriceps lines-of-action.

    PubMed

    Wilson, Nicole A; Sheehan, Frances T

    2010-08-10

    Tissue stresses and quadriceps forces are crucial factors when considering knee joint biomechanics. However, it is difficult to obtain direct, in vivo, measurements of these quantities. The primary purpose of this study was to provide the first complete description of quadriceps geometry (force directions and moment arms) of individual quadriceps components using in vivo, 3D data collected during volitional knee extension. A secondary purpose was to determine if 3D quadriceps geometry is altered in patients with patellofemoral pain and maltracking. After obtaining informed consent, cine-phase contrast (PC) MRI sets (x,y,z velocity and anatomic images) were acquired from 25 asymptomatic knees and 15 knees with patellofemoral pain during active knee extension. Using a sagittal-oblique and two coronal-oblique imaging planes, the origins and insertions of each quadriceps line-of-action were identified and tracked throughout the motion by integrating the cine-PC velocity data. The force direction and relative moment (RM) were calculated for each line-of-action. All quadriceps lines-of-action were oriented primarily in the superior direction. There were no significant differences in quadriceps geometry between asymptomatic and subjects with patellofemoral pain. However, patellofemoral kinematics were significantly different between the two populations. This study will improve the ability of musculoskeletal models to closely match in vivo human performance by providing accurate 3D quadriceps geometry and associated patellofemoral kinematics during dynamic knee motion. Furthermore, determination that quadriceps geometry is not altered in patellofemoral pain supports the use of generalized a knee model based on asymptomatic quadriceps architecture.

  6. Abdominal muscle and quadriceps strength in chronic obstructive pulmonary disease

    PubMed Central

    Man, W; Hopkinson, N; Harraf, F; Nikoletou, D; Polkey, M; Moxham, J

    2005-01-01

    Background: Quadriceps muscle weakness is common in chronic obstructive pulmonary disease (COPD) but is not observed in a small hand muscle (adductor pollicis). Although this could be explained by reduced activity in the quadriceps, the observation could also be explained by anatomical location of the muscle or fibre type composition. However, the abdominal muscles are of a similar anatomical and fibre type distribution to the quadriceps, although they remain active in COPD. Cough gastric pressure is a recently described technique that assesses abdominal muscle (and hence expiratory muscle) strength more accurately than traditional techniques. A study was undertaken to test the hypothesis that more severe weakness exists in the quadriceps than in the abdominal muscles of patients with COPD compared with healthy elderly controls. Methods: Maximum cough gastric pressure and quadriceps isometric strength were measured in 43 patients with stable COPD and 25 healthy elderly volunteers matched for anthropometric variables. Results: Despite a significant reduction in mean quadriceps strength (29.9 kg v 41.2 kg; 95% CI –17.9 to –4.6; p = 0.001), cough gastric pressure was preserved in patients with COPD (227.3 cm H2O v 204.8 cm H2O; 95% CI –5.4 to 50.6; p = 0.11). Conclusions: Abdominal muscle strength is preserved in stable COPD outpatients in the presence of quadriceps weakness. This suggests that anatomical location and fibre type cannot explain quadriceps weakness in COPD. By inference, we conclude that disuse and consequent deconditioning are important factors in the development of quadriceps muscle weakness in COPD patients, or that activity protects the abdominal muscles from possible systemic myopathic processes. PMID:15923239

  7. Profunda Femoris Pseudoaneurysm following Total Hip Arthroplasty Revision

    PubMed Central

    Harper, Katharine; Iorio, Justin; Balasubramanian, Easwaran

    2015-01-01

    Vascular injuries following total hip arthroplasty (THA) are very rare, with pseudoaneurysm being a small subset. We report a case of profunda femoris artery (PFA) pseudoaneurysm in a 61-year-old male following a posterior approach revision left THA. Presentation involved continued blood transfusion requirements several weeks postoperatively. Diagnosis of the pseduoaneurysm was made by contrast CT of the lower extremity, with confirmation via IR angiography. Successful embolization was achieved with selective coiling and Gelfoam. Presenting complaints of such complications are often vague and therefore lead to delayed diagnosis. Causes of such complications are not completely understood, particularly with PFA injuries in THA. Possible mechanisms are discussed in this paper. Vascular complications following THA can be difficult to diagnose. High suspicion in the setting of continued postoperative pain or bleeding may allow prompt diagnosis and avoidance of serious limb-threatening complications. PMID:26347839

  8. A dynamic warm-up model increases quadriceps strength and hamstring flexibility.

    PubMed

    Aguilar, Alain J; DiStefano, Lindsay J; Brown, Cathleen N; Herman, Daniel C; Guskiewicz, Kevin M; Padua, Darin A

    2012-04-01

    Research suggests that static stretching can negatively influence muscle strength and power and may result in decreased functional performance. The dynamic warm-up (DWU) is a common alternative to static stretching before physical activity, but there is limited research investigating the effects of a DWU. The purpose of this study was to compare the acute effects of a DWU and static stretching warm-up (SWU) on muscle flexibility, strength, and vertical jump using a randomized controlled trial design. Forty-five volunteers were randomly assigned into a control (CON), SWU, or DWU group. All participants rode a stationary bicycle for 5 minutes and completed a 10-minute warm-up protocol. During this protocol, the DWU group performed dynamic stretching and running, the SWU group performed static stretching, and the CON group rested. Dependent variables were measured immediately before and after the warm-up protocol. A digital inclinometer measured flexibility (degrees) for the hamstrings, quadriceps, and hip flexor muscles. An isokinetic dynamometer measured concentric and eccentric peak torque (N·m/kg) for the hamstrings and quadriceps. A force plate was used to measure vertical jump height (meters) and power (watts). In the DWU group, there was a significant increase in hamstring flexibility (pretest: 26.4 ± 13.5°, posttest: 16.9 ± 9.4°; p < .0001) and eccentric quadriceps peak torque (pretest: 2.49 ± 0.83 N·m/kg, posttest: 2.78 ± 0.69 N·m/kg; p = 0.04). The CON and SWU did not significantly affect any flexibility, strength, or vertical jump measures (p > 0.05). The DWU significantly improved eccentric quadriceps strength and hamstrings flexibility, whereas the SWU did not facilitate any positive or negative changes in muscle flexibility, strength, power, or vertical jump. Therefore, the DWU may be a better preactivity warm-up choice than an SWU.

  9. Structure relates to elastic recoil and functional role in quadriceps tendon and patellar ligament.

    PubMed

    Franchi, Marco; Quaranta, Marilisa; Macciocca, Maria; De Pasquale, Viviana; Ottani, Vittoria; Ruggeri, Alessandro

    2009-04-01

    Tendons and ligaments have similar but slightly different structure and composition. Crimps of tendons and ligaments are morphological structures related to the elastic functional properties of these connective tissues. Aim of this study was to investigate the morphological arrangement of collagen fibres, fibrils and crimping pattern of suprapatellar (rectus femoris tendon-RFT and vastus intermedius tendon-VIT) and infrapatellar connective tissues (patellar ligament-PL) to relate their structural aspects to their common function role of leg extension. RFT, VIT and PL were removed from knees of Sprague-Dawley rats and light and electron microscopy (TEM and SEM) performed. Sagittal sections showed that collagen array and crimping pattern were similar in RFT and PL but differed from VIT. Morphometric analysis confirmed that crimp number was about the same in RFT and PL (5.4+/-1.4 and 6.1+/-2.8 respectively), but it was almost three times higher in VIT (14.5+/-4.7). Similarly crimp top angle in RFT and PL (141.5+/-15.0 degrees and 146.2+/-12.2 degrees respectively) was significantly higher than in VIT (122.3+/-14.8 degrees ) and the crimp base length was more than twice as wide in RFT (75.5+/-22.6microm) and PL (72.3+/-28.9microm) than in VIT (36+/-14.1microm). The smaller, fewer and most crimped crimps in VIT show that this tendon has a greater elastic recoil and responds to higher forces as among quadriceps muscles the vastus intermedius belly contributes the most during knee extension. By contrast, RFT acting as a "stopper" tendon also plays a ligament role by limiting an excessive flexion of the joint during postural rest position of the knee.

  10. Musculo-tendon length and lengthening velocity of rectus femoris in stiff knee gait.

    PubMed

    Jonkers, Ilse; Stewart, Caroline; Desloovere, Kaat; Molenaers, Guy; Spaepen, Arthur

    2006-02-01

    Inappropriate activity of M. rectus femoris (RF) during swing is believed to contribute to stiff knee gait in cerebral palsy. This study used musculoskeletal modeling techniques to analyze rectus femoris musculo-tendon (MT) length and lengthening velocity during stiff knee gait in 35 children with diplegic cerebral palsy (CP). Duncan Ely test scores were used to categorize the patients into four groups with increasing levels of rectus femoris spasticity. Knee kinematics confirmed a significant reduction and delay of maximal peak knee flexion during swing in the patient groups compared to reference values. Maximal musculo-tendon length of M. rectus femoris was reduced and occurred prematurely in swing. Musculo-tendon lengthening velocity was significantly reduced and the timing of the maximal lengthening velocity was shifted into stance phase. The present study demonstrates altered dynamic behavior of the M. rectus femoris in stiff knee gait and the results indicate that maximal knee flexion in swing was not a valid reference for the MT length of the M. rectus femoris. Furthermore, in the patient group maximal musculo-tendon lengthening velocity of the muscle related to the stance phase rather than the stance-swing transition.

  11. Changes in Quadriceps Muscle Activity During Sustained Recreational Alpine Skiing

    PubMed Central

    Kröll, Josef; Müller, Erich; Seifert, John G.; Wakeling, James M.

    2011-01-01

    During a day of skiing thousands of repeated contractions take place. Previous research on prolonged recreational alpine skiing show that physiological changes occur and hence some level of fatigue is inevitable. In the present paper the effect of prolonged skiing on the recruitment and coordination of the muscle activity was investigated. Six subjects performed 24 standardized runs. Muscle activity during the first two (PREskiing) and the last two (POSTskiing) runs was measured from the vastus lateralis (VL) and rectus femoris (RF) using EMG and quantified using wavelet and principal component analysis. The frequency content of the EMG signal shifted in seven out of eight cases significantly towards lower frequencies with highest effects observed for RF on outside leg. A significant pronounced outside leg loading occurred during POSTskiing and the timing of muscle activity peaks occurred more towards turn completion. Specific EMG frequency changes were observed at certain time points throughout the time windows and not over the whole double turn. It is suggested that general muscular fatigue, where additional specific muscle fibers have to be recruited due to the reduced power output of other fibers did not occur. The EMG frequency decrease and intensity changes for RF and VL are caused by altered timing (coordination) within the turn towards a most likely more uncontrolled skiing technique. Hence, these data provide evidence to suggest recreational skiers alter their skiing technique before a potential change in muscle fiber recruitment occurs. Key points The frequency content of the EMG signal shifted in seven out of eight cases significantly towards lower frequencies with highest effects observed for RF. General muscular fatigue, where additional specific fibers have to be recruited due to the reduced power output of other fibers, did not occur. A modified skiing style towards a less functional and hence more uncontrolled skiing technique seems to be a key

  12. Exercise and Quadriceps Muscle Cooling Time

    PubMed Central

    Long, Blaine C; Cordova, Mitchell L; Brucker, Jody B; Demchak, Timothy J; Stone, Marcus B

    2005-01-01

    Context: Cryotherapy is commonly used for a variety of purposes; however, the body's response to cryotherapy immediately postexercise is unknown. Objective: To investigate the effect of prior exercise on crushed-ice–bag treatment of a large muscle group. Design: 2 × 3 repeated-measures design on depth (1 cm and 2 cm below adipose tissue) and treatment (exercise followed by ice, exercise followed by no ice, and no exercise followed by ice). Setting: Sports Injury Research Laboratory. Patients or Other Participants: Six physically active, uninjured male volunteers. Intervention(s): For the 2 exercise conditions, subjects rode a stationary cycle ergometer at 70% to 80% of their age-predicted maximum heart rate, as calculated by the Karvonen method. For the no-exercise condition, subjects lay supine on a treatment table. The cryotherapy treatment consisted of a 1-kg ice bag applied to the anterior mid thigh. For the no-ice condition, subjects lay supine on a treatment table. Main Outcome Measure(s): Time required for the intramuscular temperatures at the 1-cm and 2-cm depths below adipose tissue to return to pre-exercise baseline and time required to cool the 1-cm and 2-cm depths to 10°C below the pre-exercise temperature. Results: The time to cool the rectus femoris to the pre-exercise temperature using a crushed-ice–bag treatment was reduced by approximately 40 minutes (P < .001). The ice bag cooled the 1-cm and 2-cm depths to the pre-exercise temperature within 7 minutes (P = .38), but the 2-cm tissue depth took nearly 13.5 minutes longer to cool than the 1-cm depth when no ice was applied (P = .001). The 1-cm depth cooled to 10°C below the pre-exercise temperature about 8 minutes sooner than the 2-cm depth, regardless of whether the tissue was exercised or not (P < .001). Exercise shortened the cooling time to 10°C below the pre-exercise temperature by approximately 13 minutes (P = .05). Conclusions: Exercise before cooling with a crushed-ice bag enhanced

  13. Quadratus femoris: An EMG investigation during walking and running.

    PubMed

    Semciw, Adam I; Freeman, Michael; Kunstler, Breanne E; Mendis, M Dilani; Pizzari, Tania

    2015-09-18

    Dysfunction of hip stabilizing muscles such as quadratus femoris (QF) is identified as a potential source of lower extremity injury during functional tasks like running. Despite these assumptions, there are currently no electromyography (EMG) data that establish the burst activity profile of QF during any functional task like walking or running. The objectives of this study were to characterize and compare the EMG activity profile of QF while walking and running (primary aim) and describe the direction specific action of QF (secondary aim). A bipolar fine-wire intramuscular electrode was inserted via ultrasound guidance into the QF of 10 healthy participants (4 females). Ensemble curves were generated from four walking and running trials, and normalized to maximum voluntary isometric contractions (MVICs). Paired t-tests compared the temporal and amplitude EMG variables. The relative activity of QF in the MVICs was calculated. The QF displayed moderate to high amplitude activity in the stance phase of walking and very high activity during stance in running. During swing, there was minimal QF activity recorded during walking and high amplitudes were present while running (run vs walk effect size=4.23, P<0.001). For the MVICs, external rotation and clam produced the greatest QF activity, with the hip in the anatomical position. This study provides an understanding of the activity demands placed on QF while walking and running. The high activity in late swing during running may signify a synergistic role with other posterior thigh muscles to control deceleration of the limb in preparation for stance.

  14. The Effect of Concentric Isokinetic Strength Training of the Quadriceps Femoris on Electromyography and Muscle Strength in the Trained and Untrained Limb.

    ERIC Educational Resources Information Center

    Evetovich, Tammy K.; Housh, Terry J.; Housh, Dona J.; Johnson, Glen O.; Smith, Douglas B.; Ebersole, Kyle T.

    2001-01-01

    Examined the effects of unilateral concentric isokinetic leg extension training on peak torque and electromyographic (EMG) responses in trained and untrained limbs. Adult men participated in training and control groups. Overall, unilateral concentric isokinetic strength training induced strength increases in trained as well as untrained limbs.…

  15. Rectus femoris transfer and musculo-skeletal modeling: effect of surgical treatment on gait and on rectus femoris kinematics.

    PubMed

    Desailly, Eric; Khouri, Nejib; Sardain, Philippe; Yepremian, Daniel; Lacouture, Patrick

    2011-10-01

    Spasticity of the rectus femoris (RF) is one of the possible causes of stiff knee gait (SKG) in cerebral palsy. Musculoskeletal studies have shown that in SKG, length and speed of the RF are affected. No evaluation had been made to quantify the modifications of those parameters after surgery. The effect of this operation on gait quality and on RF kinematics was assessed in this study in order to identify kinematic patterns that may aid its diagnosis. For 26 transfers, clinical gait analysis pre- and post-surgery was used to compute the Gait Deviation Index (GDI) and Goldberg's index. The kinematics of the Original RF path (ORFp) was studied before and after surgery. The expression ORFp was chosen to avoid any confusion between this modeling parameter, whose computation was unchanged, and the actual anatomical path that was modified by surgery. The gait quality was improved (+18±12GDI) and there was an inverse relation between the pre-operative GDI and its improvement. The Golberg's index was improved (88% of the cases). The operation had a significant effect on the normalization of the timings of maximum length and speed of the ORFp. The improvement of SKG was correlated with the normalization of the timing of the ORFp's maximum length. The global improvement of the gait quality and of the SKG was demonstrated. Some parameters of muscular kinematics (RF length and velocity) have been standardized, showing an effect of the transfer not only during the swing, but also during stance. The premature timing of the ORFp peak length has been identified as a prognostic factor of a successful surgical outcome.

  16. Acute effects of static stretching on peak and end-range hamstring-to-quadriceps functional ratios

    PubMed Central

    Sekir, Ufuk; Arabaci, Ramiz; Akova, Bedrettin

    2015-01-01

    AIM: To evaluate if static stretching influences peak and end-range functional hamstring-to-quadriceps (H/Q) strength ratios in elite women athletes. METHODS: Eleven healthy female athletes in an elite competitive level participated to the study. All the participants fulfilled the static stretching or non-stretching (control) intervention protocol in a randomized design on different days. Two static unassisted stretching exercises, one in standing and one in sitting position, were used to stretch both the hamstring and quadriceps muscles during these protocols. The total time for the static stretching was 6 ± 1 min. The isokinetic peak torque measurements for the hamstring and quadriceps muscles in eccentric and concentric modes and the calculations for the functional H/Q strength ratios at angular velocities of 60°/s and 180°/s were made before (pre) and after (post) the control or stretching intervention. The strength measurements and functional strength ratio calculations were based during the entire- and end-range of knee extension. RESULTS: The pre-test scores for quadriceps and hamstring peak torque and end range values were not significantly different between the groups (P > 0.05). Subsequently, although the control group did not exhibit significant changes in quadriceps and hamstring muscle strength (P > 0.05), static stretching decreased eccentric and concentric quadriceps muscle strength at both the 60°/s and 180°/s test speeds (P < 0.01). Similarly, static stretching also decreased eccentric and concentric hamstring muscle strength at both the 60°/s and 180°/s test speeds (P < 0.01). On the other hand, when the functional H/Q strength ratios were taken into consideration, the pre-intervention values were not significant different between the groups both during the entire and end range of knee extension (P > 0.05). Furthermore, the functional H/Q strength ratios exhibited no significant alterations during the entire and end ranges of knee extension

  17. Central and peripheral quadriceps fatigue in congestive heart failure☆

    PubMed Central

    Hopkinson, Nicholas S.; Dayer, Mark J.; Antoine-Jonville, Sophie; Swallow, Elisabeth B.; Porcher, Raphael; Vazir, Ali; Poole-Wilson, Philip; Polkey, Michael I.

    2013-01-01

    Aims The clinical syndrome of heart failure includes exercise limitation that is not directly linked to measures of cardiac function. Quadriceps fatigability may be an important component of this and this may arise from peripheral or central factors. Methods and results We studied 10 men with CHF and 10 healthy age-matched controls. Compared with a rest condition, 10 min after incremental maximal cycle exercise, twitch quadriceps force in response to supramaximal magnetic femoral nerve stimulation fell in both groups (CHF 14.1% ± 18.1%, p = 0.037; Control: 20.8 ± 11.0%, p < 0.001; no significant difference between groups). There was no significant change in quadriceps maximum voluntary contraction voluntary force. The difference in the motor evoked potential (MEP) response to transcranial magnetic stimulation of the motor cortex between rest and exercise conditions at 10 min, normalised to the peripheral action potential, also fell significantly in both groups (CHF: 27.3 ± 38.7%, p = 0.037; Control: 41.1 ± 47.7%, p = 0.024). However, the fall in MEP was sustained for a longer period in controls than in patients (p = 0.048). Conclusions The quadriceps is more susceptible to fatigue, with a similar fall in TwQ occurring in CHF patients at lower levels of exercise. This is associated with no change in voluntary activation but a lesser degree of depression of quadriceps motor evoked potential. PMID:22795722

  18. Shear-Wave Elastography Assessments of Quadriceps Stiffness Changes prior to, during and after Prolonged Exercise: A Longitudinal Study during an Extreme Mountain Ultra-Marathon.

    PubMed

    Andonian, Pierre; Viallon, Magalie; Le Goff, Caroline; de Bourguignon, Charles; Tourel, Charline; Morel, Jérome; Giardini, Guido; Gergelé, Laurent; Millet, Grégoire P; Croisille, Pierre

    2016-01-01

    In sports medicine, there is increasing interest in quantifying the elastic properties of skeletal muscle, especially during extreme muscular stimulation, to improve our understanding of the impact of alterations in skeletal muscle stiffness on resulting pain or injuries, as well as the mechanisms underlying the relationships between these parameters. Our main objective was to determine whether real-time shear-wave elastography (SWE) can monitor changes in quadriceps muscle elasticity during an extreme mountain ultra-marathon, a powerful mechanical stress model. Our study involved 50 volunteers participating in an extreme mountain marathon (distance: 330 km, elevation: +24,000 m). Quantitative SWE velocity and shear modulus measurements were performed in most superficial quadriceps muscle heads at the following 4 time points: before the race, halfway through the race, upon finishing the race and after recovery (+48 h). Blood biomarker levels were also measured. A significant decrease in the quadriceps shear modulus was observed upon finishing the race (3.31±0.61 kPa) (p<0.001) compared to baseline (3.56±0.63 kPa), followed by a partial recovery +48 h after the race (3.45±0.6 kPa) (p = 0.002) across all muscle heads, as well as for each of the following three muscle heads: the rectus femoris (p = 0.003), the vastus medialis (p = 0.033) and the vastus lateralis (p = 0.001). Our study is the first to assess changes in muscle stiffness during prolonged extreme physical endurance exercises based on shear modulus measurements using non-invasive SWE. We concluded that decreases in stiffness, which may have resulted from quadriceps overuse in the setting of supra-physiological stress caused by the extreme distance and unique elevation of the race, may have been responsible for the development of inflammation and muscle swelling. SWE may hence represent a promising tool for monitoring physiologic or pathological variations in muscle stiffness and may be useful for

  19. Shear-Wave Elastography Assessments of Quadriceps Stiffness Changes prior to, during and after Prolonged Exercise: A Longitudinal Study during an Extreme Mountain Ultra-Marathon

    PubMed Central

    Andonian, Pierre; Viallon, Magalie; Le Goff, Caroline; de Bourguignon, Charles; Tourel, Charline; Morel, Jérome; Giardini, Guido; Gergelé, Laurent; Millet, Grégoire P.; Croisille, Pierre

    2016-01-01

    In sports medicine, there is increasing interest in quantifying the elastic properties of skeletal muscle, especially during extreme muscular stimulation, to improve our understanding of the impact of alterations in skeletal muscle stiffness on resulting pain or injuries, as well as the mechanisms underlying the relationships between these parameters. Our main objective was to determine whether real-time shear-wave elastography (SWE) can monitor changes in quadriceps muscle elasticity during an extreme mountain ultra-marathon, a powerful mechanical stress model. Our study involved 50 volunteers participating in an extreme mountain marathon (distance: 330 km, elevation: +24,000 m). Quantitative SWE velocity and shear modulus measurements were performed in most superficial quadriceps muscle heads at the following 4 time points: before the race, halfway through the race, upon finishing the race and after recovery (+48 h). Blood biomarker levels were also measured. A significant decrease in the quadriceps shear modulus was observed upon finishing the race (3.31±0.61 kPa) (p<0.001) compared to baseline (3.56±0.63 kPa), followed by a partial recovery +48 h after the race (3.45±0.6 kPa) (p = 0.002) across all muscle heads, as well as for each of the following three muscle heads: the rectus femoris (p = 0.003), the vastus medialis (p = 0.033) and the vastus lateralis (p = 0.001). Our study is the first to assess changes in muscle stiffness during prolonged extreme physical endurance exercises based on shear modulus measurements using non-invasive SWE. We concluded that decreases in stiffness, which may have resulted from quadriceps overuse in the setting of supra-physiological stress caused by the extreme distance and unique elevation of the race, may have been responsible for the development of inflammation and muscle swelling. SWE may hence represent a promising tool for monitoring physiologic or pathological variations in muscle stiffness and may be useful for

  20. Quantifying Quadriceps Muscle Strength in Patients With ACL Injury, Focal Cartilage Lesions, and Degenerative Meniscus Tears

    PubMed Central

    Eitzen, Ingrid; Grindem, Hege; Nilstad, Agnethe; Moksnes, Håvard; Risberg, May Arna

    2016-01-01

    Background: Reduced quadriceps strength influences knee function and increases the risk of knee osteoarthritis. Thus, it is of significant clinical relevance to precisely quantify strength deficits in patients with knee injuries. Purpose: To evaluate isokinetic concentric quadriceps muscle strength torque values, assessed both from peak torque and at specific knee flexion joint angles, in patients with anterior cruciate ligament (ACL) injury, focal cartilage lesions, and degenerative meniscus tears. Study Design: Cohort study; Level of evidence, 3. Methods: Data were synthesized from patients included in 3 previously conducted research projects: 2 prospective cohort studies and 1 randomized controlled trial. At the time of inclusion, all patients were candidates for surgery. Isokinetic concentric quadriceps muscle strength measurements (60 deg/s) were performed at baseline (preoperative status) and after a period of progressive supervised exercise therapy (length of rehabilitation period: 5 weeks for ACL injury, 12 weeks for cartilage lesions and degenerative meniscus). Outcome measures were peak torque and torque at specific knee flexion joint angles from 20° to 70°. All patients had unilateral injuries, and side-to-side deficits were calculated. For comparisons between and within groups, we utilized 1-way analysis of variance and paired t tests, respectively. Results: In total, 250 patients were included. At baseline, cartilage patients had the most severe deficit (39.7% ± 24.3%; P < .001). Corresponding numbers for ACL and degenerative meniscus subjects were 21.7% (±13.2%) and 20.7% (±16.3%), respectively. At retest, there was significant improvement in all groups (P < .001), with remaining deficits of 24.7% (±18.5%) for cartilage, 16.8% (±13.9%) for ACL, and 3.3% (±17.8%) for degenerative meniscus. Peak torque was consistently measured at 60° of knee flexion, whereas the largest mean deficits were measured at 30° at baseline and 70° at retest for the

  1. Giant pseudocyst of the rectus femoris muscle--repetitive strain injury in recreational soccer player.

    PubMed

    Cicvarić, Tedi; Lucin, Ksenija; Roth, Sandor; Ivancić, Aldo; Marinović, Marin; Santić, Veljko

    2010-04-01

    We report a case of a traumatic pseudocyst, in a recreational soccer player, after rupture of rectus femoris muscle. 37-year-old male, with history of repetitive painful accidents, was examined because of a double fist-sized mass in the anterior thigh. Ultrasound examination revealed a cystic mass in the rectus femoris muscle. Surgical removal of the mass and proximal remnant of muscle was done. Primary healing and functional recovery was achieved. Histological analysis revealed pseudocyst filled with degenerating clot and surrounded with thick fibrous capsule. The repetitive strain muscle injury, with prolonged period of healing, can occur like pseudocyst.

  2. Quadriceps Muscle Function After Exercise in Men and Women With a History of Anterior Cruciate Ligament Reconstruction

    PubMed Central

    Kuenze, Christopher M.; Hertel, Jay; Hart, Joseph M.

    2014-01-01

    Context: Sex differences in lower extremity neuromuscular function have been reported after anterior cruciate ligament reconstruction (ACLR). Research evidence supports different levels of fatigability in men and women and between patients with ACLR and healthy controls. The influence of sex on the response to continuous exercise in patients with ACLR is not clear. Objective: To compare quadriceps neuromuscular function after exercise between men and women with ACLR. Design: Descriptive laboratory study. Setting: Laboratory. Patients or Other Participants: Twenty-six active volunteers (13 men [50%]: age = 24.1 ± 4.4 years, height = 179.1 ± 9.8 cm, mass = 80.1 ± 9.4 kg, months since surgery = 43.5 ± 37.0; 13 women [50%]: age = 24.2 ± 5.6 years, height = 163.0 ± 5.9 cm, mass = 62.3 ± 8.3 kg, months since surgery = 45.8 ± 42.7) with a history of unilateral primary ACLR at least 6 months earlier. Intervention(s): Thirty minutes of continuous exercise comprising 5 separate 6-minute cycles, including 5 minutes of uphill walking and 1 minute of body-weight squatting and step-ups. Main Outcome Measure(s): Normalized knee-extension maximal voluntary isometric contraction torque, quadriceps superimposed-burst torque, and quadriceps central activation ratio before and after exercise. We performed separate 2 (sex: men, women) × 2 (time: preexercise, postexercise) repeated-measures analyses of variance for the 3 variables. Separate, independent-samples t tests were calculated to compare preexercise with postexercise change in all dependent variables between sexes. Results: A significant group-by-time interaction was present for knee-extension torque (P = .04). The percentage reduction in knee-extension maximal voluntary isometric contraction torque (men = 1.94%, women = −10.32%; P = .02) and quadriceps central activation ratio (men = −1.45%, women = −8.69%; P = .03) experienced by men was less than that observed in women. Conclusions: In the presence of

  3. Acute calcific tendinitis of the rectus femoris associated with intraosseous involvement: a case report with serial CT and MRI findings.

    PubMed

    Kim, Young Sung; Lee, Ho Min; Kim, Jong Pil

    2013-11-01

    Acute calcific tendinitis of the shoulder is a well-known condition, but it is rare in the rectus femoris origin. Mostly reported cases were occurred in the reflected head of the rectus femoris, and only few cases were in the direct head of the rectus femoris. Intraosseous marrow involvement of calcific tendinitis is a more rare condition; it often goes misdiagnosed as an infection or a neoplasm. We report a rare, unusual case of acute calcific tendinitis of the direct head of the rectus femoris associated with intraosseous marrow involvement of calcification in anterior inferior iliac spine with serial CT and MRI findings. Aggressive osseous change may occur in acute calcific tendinitis of the rectus femoris as in this case which should be made an appropriate diagnosis to avoid unnecessary investigation and overtreatment like a surgery.

  4. Rabbit rectus femoris muscle for ischemia-reperfusion studies: an improved model.

    PubMed

    Hoballah, J J; Mohan, C R; Schipper, P H; Chalmers, R T; Corry, D C; Corson, J D

    1996-11-01

    The rabbit rectus femoris muscle was evaluated as a potential model for skeletal muscle reperfusion injury studies. Six white New Zealand rabbits were used. On one randomly selected hind limb, ischemia was induced by direct clamping of the rectus femoris muscle's vascular pedicle. On the other side, blood flow was interrupted by clamping the femoral artery above and below the origin of the vascular pedicle that supplies the rectus femoris muscle. The duration of normothermic ischemia was 4 hr and was followed by 24 hr of normothermic reperfusion. The interruption and restoration of blood flow was monitored using a laser flow meter. The rectus femoris muscles were weighed on a suspension spring balance prior to ischemia and at the end of reperfusion to estimate edema. The extent of muscle necrosis was determined using planimetry following staining with nitroblue tetrazolium. The muscle necrosis obtained by direct clamping of the vascular pedicle (66.9 +/- 14.3%) was significantly greater than that obtained by indirect clamping (18.6 +/- 11.4%) (P < 0.03 by t test). Unlike the indirect clamping technique, direct clamping achieved a good magnitude of muscle necrosis, thus allowing that specific model to be used in skeletal muscle reperfusion injury studies. The muscle weight gain observed in the direct clamping muscle group was 19.8 +/- 9.0% and was significantly greater than that observed in the opposite group being 6.3 +/- 6.5% (P < 0.05 by t test). The rabbit rectus femoris muscle is a suitable model for evaluating skeletal muscle reperfusion injury provided that direct clamping of the vascular pedicle is utilized.

  5. Effect of Knee Position on Quadriceps Muscle Force Steadiness and Activation Strategies

    PubMed Central

    Krishnan, Chandramouli; Allen, Eric J.; Williams, Glenn N.

    2010-01-01

    Introduction This study investigated the effect of knee position on quadriceps force steadiness and activation strategies. Methods Quadriceps force steadiness was evaluated in twenty-two volunteers at two knee positions by testing their ability to regulate submaximal force. Muscle activation strategies were studied in both time and frequency domains using surface electromyography. Results Quadriceps force fluctuations and the associated agonist and antagonist activity were significantly higher at 90° than at 30° of flexion (P < 0.05). The quadriceps median frequency recorded at 30° was significantly higher than at 90° of flexion (P < 0.05). Regression analyses revealed that force steadiness was related to quadriceps activation and median frequency (P < 0.001), but not to hamstring coactivation (P > 0.05). Discussion The results indicate that knee position significantly affects quadriceps force steadiness and activation strategies. This finding may have important implications for designing a force control testing protocol and interpreting test results. PMID:21404288

  6. Complete paralysis of the quadriceps muscle caused by traumatic iliacus hematoma: a case report.

    PubMed

    Tamai, Kazuya; Kuramochi, Taro; Sakai, Hiroya; Iwami, Norio; Saotome, Koichi

    2002-01-01

    A15-year-old girl who developed traumatic iliacus hematoma and complete paralysis of the quadriceps muscle is reported. The current case and literature review revealed that incomplete quadriceps paralysis associated with traumatic iliacus hematoma is likely to progress to complete paralysis in days or weeks as a result of increased intracompartmental pressure. However, surgical decompression of the femoral nerve could produce good results even in patients who have complete quadriceps paralysis preoperatively.

  7. Quadriceps strength and weight acceptance strategies continue to improve two years after anterior cruciate ligament reconstruction

    PubMed Central

    Roewer, Ben D.; Di Stasi, Stephanie L.; Snyder-Mackler, Lynn

    2011-01-01

    The anterior cruciate ligament (ACL) is the most commonly-injured knee ligament during sporting activities. After injury, most individuals experience episodes of the knee giving way during daily activities (non-copers). Non-copers demonstrate asymmetrical quadriceps strength and movement patterns which could have long-term deleterious effects on the integrity of the knee joint. The purpose of this study was to determine if non-copers resolve their strength and movement asymmetries within two years after surgery. 26 non-copers were recruited to undergo pre-operative quadriceps strength testing and 3-dimensional gait analysis. Subjects underwent surgery to reconstruct the ligament followed by physical therapy focused on restoring normal range of motion, quadriceps strength, and function. Subjects returned for quadriceps strength testing and gait analysis six months and two years after surgery. Acutely after injury, quadriceps strength was asymmetric between limbs, but resolved six months after surgery. Asymmetric knee angles, knee moments, and knee and hip power profiles were also observed acutely after injury and persisted six months after surgery despite subjects achieving symmetrical quadriceps strength. Two years after surgery, quadriceps strength in the involved limb continued to improve and most kinematic and kinetic asymmetries resolved. These findings suggest that adequate quadriceps strength does not immediately resolve gait asymmetries in non-copers. They also suggest that non-copers have the capacity to improve their quadriceps strength and gait symmetry long after ACL reconstruction. PMID:21592482

  8. Effect of 3 Different Applications of Kinesio Taping Denko® on Electromyographic Activity: Inhibition or Facilitation of the Quadriceps of Males During Squat Exercise

    PubMed Central

    Serrão, Júlio C.; Mezêncio, Bruno; Claudino, João G.; Soncin, Rafael; Miyashiro, Pedro L. Sampaio; Sousa, Eric P.; Borges, Eduardo; Zanetti, Vinícius; Phillip, Igor; Mochizuki, Luiz; Amadio, Alberto C.

    2016-01-01

    Kinesio taping consists of a technique which uses the application of an elastic adhesive tape. It has become a widely used rehabilitation modality for the prevention and treatment of musculoskeletal disorders. The objective of this study was to verify the effect of the application of Kinesio Taping Denko® in three conditions (facilitation, inhibition, and placebo) on the electromyographic activity of the quadriceps and hamstrings muscles on facilitating or inhibiting the muscle function and on the perceived exertion during the barbell back squat exercise in healthy male subjects. Methods: It was a randomized, single-blinded and controlled study in which 18 males (28.0 ± 6.7 years old; 85.8 ± 8.2 kg mass; 1.80 ± 0.07 m tall; 0.97 ± 0.04 m lower limb length) performed barbell back squat exercise with different conditions of Kinesio Taping Denko® applications: Facilitation, inhibition and placebo. Previous to the mentioned conditions, all individuals were assessed without applying kinesio Taping Denko® during the exercise. OMNI scale was used after each set for perceived exertion evaluation. No differences (p < 0.05) in the electromyographic activity of the biceps femoris, vastus lateralis and vastus medialis or OMNI scale were recorded under any conditions. The results show that the kinesio taping denko®may not alter the magnitude of the electromyography activity of vastus lateralis, vastus medialis, and biceps femoris during the squat exercise. Furthermore, the perceived exertion was not affected by the kinesio taping denko® application. Key points Researchers involved in collecting data in this study have no financial or personal interest in the outcome of results or the sponsor. The perceived exertion was not affected by the kinesiology taping application. Kinesiology taping application may not alter the magnitude of EMG activity of vastuslateralis, vastusmedialis, and biceps femoris during the barbell back squat exercise. Electromyographic activity of

  9. Calcific tendinitis of biceps femoris: an unusual site and cause for lateral knee pain.

    PubMed

    Chan, Warwick; Chase, Helen Emily; Cahir, John G; Walton, Neil Patrick

    2016-07-29

    A 37-year-old man presented to the acute knee and sports medicine clinic with atraumatic lateral knee pain. He had point tenderness over the lateral aspect of his knee which had not settled with anti-inflammatory medications. Imaging revealed a large opaque lesion lateral to the knee and although there was no clear mechanism, injury to the posterolateral corner was considered. An MRI subsequently revealed a rare case of calcific tendinitis to the biceps femoris tendon insertion. This condition was self-limiting and did not require interventions such as steroid injections. This is the first reported case of calcific tendinitis of biceps femoris as a cause of acute knee pain.

  10. Successful Treatment of Rectus Femoris Calcification with Ultrasound-guided Injection: A Case Report

    PubMed Central

    Hong, Myong Joo; Park, Jeong Ki; Kang, Tai Ug

    2015-01-01

    Painful periarticular calcification most commonly occurs within the rotator cuff of the shoulder and rarely around the elbow, hip, foot, and neck. As acute inflammatory reaction develops, severe pain, exquisite tenderness, local swelling, and limitation of motion with pain occur. In case of calcific tendinitis of the shoulder, it can be easily diagnosed according to the symptoms and with x-ray. However, in lesions of the hip, as it is a rare location and usually involves pain in the posterolateral aspect of the thigh, which can simulate radicular pain from a lumbar intervertebral disc, it could be difficult to diagnose. Hence, physicians usually focus on lumbar lesions; therefore, misdiagnosis is common and leads to a delayed management. Here, we report the case of a 30-year-old female patient with calcific tendinitis of the rectus femoris that was successfully managed with ultrasound-guided steroid injection. This study offers knowledge about the rectus femoris calcification. PMID:25589947

  11. Ruptured profunda femoris aneurysm secondary to neurofibromatosis: vascular involvement in an unusual location.

    PubMed

    Emrecan, Bilgin; Onem, Gokhan; Susam, Ibrahim

    2010-01-01

    Neurofibromatosis is an autosomal dominant genetic disease characterized by abnormal growth that involves tissues of mesodermal and neuroectodermal origin. Aneurysms are rarely seen in peripheral arteries. This report presents a case of ruptured arterial aneurysm secondary to neurofibromatosis; the lesion occurred in the profunda femoris artery, a highly unusual location. Treatment of patients with ruptured arterial aneurysm secondary to neurofibromatosis may be interventional or surgical. In this case, a surgical approach was successful.

  12. Proteome Changes in biceps femoris Muscle of Iranian
One-Humped Camel and Their Effect on Meat Quality Traits

    PubMed Central

    Varidi, Mohammad-Javad; Varidi, Mehdi

    2016-01-01

    Summary In this study physicochemical and quality traits of biceps femoris and longissimus thoracis muscles of male and female Iranian one-humped camel were determined during 14 days of refrigeration storage. Analysis of variance of the results showed that only shear force and temperature were affected by the gender (p<0.05). Anatomical location of the muscle influenced the meat properties except for drip loss (p<0.05). Also, except for cooking loss, ageing influenced the physicochemical and quality properties of meat; during 14 days of storage, proteolysis resulted in an increase of L* and b* values, drip loss and myofibrillar fragmentation index, and the decrease of a* value, expressed juice, shear force and sarcomere length. Proteome changes (myofibrillar proteins) during storage were investigated. Gel analysis revealed that 19 protein spots were significantly changed during 24, 72 and 168 h post-mortem. Fifteen spots were identified by MALDI-TOF/TOF mass spectrometer. Correlation analysis revealed significant correlations of actin, troponin T, capping protein, heat shock proteins (HSP) and desmin with physicochemical and quality properties of meat (p<0.05). Actin might be a potential protein marker for colour, tenderness and water-holding capacity, and HSP27 and desmin are good candidate markers for colour and tenderness, respectively. PMID:27956864

  13. Implementation of Open and Closed Kinetic Chain Quadriceps Strengthening Exercises after Anterior Cruciate Ligament Reconstruction.

    ERIC Educational Resources Information Center

    Ross, Michael D.; Denegar, Craig R.; Winzenried, Jay A.

    2001-01-01

    Reviews the effects of open kinetic chain (OKC) and closed kinetic chain (CKC) exercise on anterior cruciate ligament (ACL) strain and patellofemoral joint stress, suggesting a combination of the two for quadriceps strengthening after ACL reconstruction. Both OKC and CKC exercises may be modified and implemented for quadriceps strengthening after…

  14. Comparison of the hamstring/quadriceps ratio in females during squat exercise using various foot wedges

    PubMed Central

    Yoo, Won-gyu

    2016-01-01

    [Purpose] This study compared the hamstring/quadriceps ratio in females during squat exercise using various foot wedges. [Subjects and Methods] Nine females participated in this study. Surface electrodes measurements were taken over the hamstring and quadriceps under 3 squat exercise conditions, and the hamstring/quadriceps ratio was calculated. [Results] The hamstring/quadriceps ratio was significantly increased during squat exercise in inclined wedge condition (7.4 ± 1.8), compared to the declined wedge condition (5.3 ± 2.2) and no wedge condition (6.4 ± 3.2). [Conclusion] This study suggests that squat exercise in the inclined wedge condition may be effective for increasing the hamstring/quadriceps ratio in females. PMID:27630437

  15. The correlation between muscle activity of the quadriceps and balance and gait in stroke patients

    PubMed Central

    Yang, Dae Jung; Park, Seung Kyu; Uhm, Yo Han; Park, Sam Heon; Chun, Dong Whan; Kim, Je Ho

    2016-01-01

    [Purpose] The purpose of this study was to examine the correlation between quadriceps muscle activity and balance and gait in stroke patients. [Subjects and Methods] Fifty-five stroke patients (30 males 25 females; mean age 58.7 years; stroke duration 4.82 months; Korean mini-mental state examination score 26.4) participated in this study. MP100 surface electromyography, BioRescue, and LUKOtronic were used to measure the quadriceps muscle activity, balance, and gait, respectively. [Results] There was a significant correlation between quadriceps muscle activity (vastus lateralis % reference voluntary contraction, vastus medialis % reference voluntary contraction) and balance (limits of stability) and gait (gait velocity) but there was none between vastus lateralis % reference voluntary contraction, vastus medialis % reference voluntary contraction. [Conclusion] An increase in quadriceps muscle activity will improve balance and gait ability. To improve function in stroke patients, training is needed to strengthen the quadriceps muscles. PMID:27630416

  16. Can an anterior quadriceps release improve range of motion in the stiff arthritic knee?

    PubMed

    Tarabichi, Samih; Tarabichi, Yasir

    2010-06-01

    We hypothesize that tethering adhesions of the quadriceps muscle are the major pathological structures responsible for a limited range of motion in the stiff arthritic knee. Forty-two modified quadriceps muscle releases were performed on 24 patients with advanced osteoarthritis scheduled for total knee arthroplasty. The ranges of motion were documented intraoperatively both before and immediately after the release. Passive flexion improved significantly in all patients (mean, 32.4 degrees of improvement, P < .001) following a modified quadriceps release, despite any presence of osteophytes or severe deformities. These results strongly implicate adhesions of the quadriceps muscle to the underlying femur, which prevent the distal excursion of the quadriceps tendon, as the restrictive pathology preventing deep flexion in patients with osteoarthritis.

  17. Comparison of the hamstring/quadriceps ratio in females during squat exercise using various foot wedges.

    PubMed

    Yoo, Won-Gyu

    2016-08-01

    [Purpose] This study compared the hamstring/quadriceps ratio in females during squat exercise using various foot wedges. [Subjects and Methods] Nine females participated in this study. Surface electrodes measurements were taken over the hamstring and quadriceps under 3 squat exercise conditions, and the hamstring/quadriceps ratio was calculated. [Results] The hamstring/quadriceps ratio was significantly increased during squat exercise in inclined wedge condition (7.4 ± 1.8), compared to the declined wedge condition (5.3 ± 2.2) and no wedge condition (6.4 ± 3.2). [Conclusion] This study suggests that squat exercise in the inclined wedge condition may be effective for increasing the hamstring/quadriceps ratio in females.

  18. A new isometric quadriceps-strengthening exercise using EMG-biofeedback

    PubMed Central

    Kesemenli, Cumhur C; Sarman, Hakan; Baran, Tuncay; Memisoglu, Kaya; Binbir, Ismail; Savas, Yilmaz; Isik, Cengiz; Boyraz, Ismail; Koc, Bunyamin

    2014-01-01

    A new isometric contraction quadriceps-strengthening exercise was developed to restore the quadriceps strength lost after knee surgery more rapidly. This study evaluated the results of this new method. Patients were taught to perform the isometric quadriceps-strengthening exercise in the unaffected knee in the supine position, and then they performed it in the affected knee. First, patients were taught the classical isometric quadriceps-strengthening exercise, and then they were taught our new alternative method: “pull the patella superiorly tightly and hold the leg in the same position for 10 seconds”. Afterward, the quadriceps contraction was evaluated using a non-invasive Myomed 932 EMG-biofeedback device (Enraf-Nonius, The Netherlands) with gel-containing 48 mm electrodes (Türklab, The Turkey) placed on both knees. The isometric quadriceps-strengthening exercise performed using our new method had stronger contraction than the classical method (P < 0.01). The new method involving pulling the patella superiorly appears to be a better choice, which can be applied easily, leading to better patient compliance and greater quadriceps force after arthroscopic and other knee surgeries. PMID:25356122

  19. Preferential reduction of quadriceps over respiratory muscle strength and bulk after lung transplantation for cystic fibrosis

    PubMed Central

    Pinet, C; Scillia, P; Cassart, M; Lamotte, M; Knoop, C; Melot, C; Estenne, M

    2004-01-01

    Background: In the absence of complications, recipients of lung transplants for cystic fibrosis have normal pulmonary function but the impact of the procedure on the strength and bulk of respiratory and limb muscles has not been studied. Methods: Twelve stable patients who had undergone lung transplantation for cystic fibrosis 48 months earlier (range 8–95) and 12 normal subjects matched for age, height, and sex were studied. The following parameters were measured: standard lung function, peak oxygen uptake by cycle ergometry, diaphragm surface area by computed tomographic (CT) scanning, diaphragm and abdominal muscle thickness by ultrasonography, twitch transdiaphragmatic and gastric pressures, quadriceps isokinetic strength, and quadriceps cross section by CT scanning, and lean body mass. Diaphragm mass was computed from diaphragm surface area and thickness. Results: Twitch transdiaphragmatic and gastric pressures, diaphragm mass, and abdominal muscle thickness were similar in the two groups but quadriceps strength and cross section were decreased by nearly 30% in the patients. Patients had preserved quadriceps strength per unit cross section but reduced quadriceps cross section per unit lean body mass. The cumulative dose of corticosteroids was an independent predictor of quadriceps atrophy. Peak oxygen uptake showed positive correlations with quadriceps strength and cross section in the two groups, but peak oxygen uptake per unit quadriceps strength or cross section was reduced in the patient group. Conclusions: The diaphragm and abdominal muscles have preserved strength and bulk in patients transplanted for cystic fibrosis but the quadriceps is weak due to muscle atrophy. This atrophy is caused in part by corticosteroid therapy and correlates with the reduction in exercise capacity. PMID:15333856

  20. Quadriceps Inhibition After Repetitive Lumbar Extension Exercise in Persons With a History of Low Back Pain

    PubMed Central

    Hart, Joseph M; Fritz, Julie M; Kerrigan, D. Casey; Saliba, Ethan N; Gansneder, Bruce M; Ingersoll, Christopher D

    2006-01-01

    Context: A neuromuscular relationship exists between the lumbar extensor and quadriceps muscles during fatiguing exercise. However, this relationship may be different for persons with low back pain (LBP). Objective: To compare quadriceps inhibition after isometric, fatiguing lumbar extension exercise between persons with a history of LBP and control subjects. Design: A 2 × 3 factorial, repeated-measures, time-series design with independent variables of group (persons with a history of LBP, controls) and time (baseline, postexercise set 1, postexercise set 2). Setting: University research laboratory. Patients or Other Participants: Twenty-five subjects with a history of LBP were matched by sex, height, and mass to 25 healthy control subjects. Intervention(s): Electromyography median frequency indexed lumbar paraspinal muscular fatigue while subjects performed 2 sets of isometric lumbar extension exercise. Subjects exercised until a 15% downward shift in median frequency for the first set and a 25% shift for the second set were demonstrated. Main Outcome Measure(s): Knee extension force was measured while subjects performed an isometric maximal quadriceps contraction. During this maximal effort, a percutaneous electric stimulus was applied to the quadriceps, causing a transient, supramaximal increase in force output. We used the ratio between the 2 forces to estimate quadriceps inhibition. Quadriceps electromyographic activity was recorded during the maximal contractions to compare median frequencies over time. Results: Both groups exhibited significantly increased quadriceps inhibition after the first (12.6% ± 10.0%, P < .001) and second (15.2% ± 9.7%, P < .001) exercise sets compared with baseline (9.6% ± 9.3%). However, quadriceps inhibition was not different between groups. Conclusions: Persons with a history of LBP do not appear to be any more or less vulnerable to quadriceps inhibition after fatiguing lumbar extension exercise. PMID:17043693

  1. Use of Ultrasound to Monitor Biceps Femoris Mechanical Adaptations after Injury in a Professional Soccer Player.

    PubMed

    Kellis, Eleftherios; Galanis, Nikiforos; Chrysanthou, Chrysanthos; Kofotolis, Nikolaos

    2016-03-01

    This study examined the use of ultrasound to monitor changes in the long head of the biceps femoris (BF) architecture of aprofessional soccer player with acute first-time hamstring strain. The player followed a 14 session physiotherapy treatment until return to sport. The pennation angle and aponeurosis strain of the long head of the biceps femoris (BF) were monitored at 6 occasions (up until 1 year) after injury. The size of the scar / hematoma was reduced by 63.56% (length) and 67.9% (width) after the intervention and it was almost non-traceable one year after injury. The pennation angle of the fascicles underneath the scar showed a decline of 51.4% at the end of the intervention while an increase of 109.2% of the fascicles which were closer to deep aponeurosis was observed. In contrast, pennation angle of fascicles located away from the injury site were relatively unaffected. The treatment intervention resulted in a 57.9% to 77.3% decline of maximum strain per unit of MVC moment and remained similar one year after the intervention. This study provided an example of the potential use of ultrasound-based parameters to link the mechanical adaptations of the injured muscle to specific therapeutic intervention. Key pointsChanges in fascicle orientation after biceps femoris mild tear were reduced after a 28 day intervention and remained similar one year after injury.Tendon/aponeurosis strain per unit of moment of force decreased during the course of the therapeutic intervention.Future studies could utilize ultrasonography to monitor mechanical responses after various types of hamstring injury and interventions in order to improve criteria for a safe return to sport.

  2. Use of Ultrasound to Monitor Biceps Femoris Mechanical Adaptations after Injury in a Professional Soccer Player

    PubMed Central

    Kellis, Eleftherios; Galanis, Nikiforos; Chrysanthou, Chrysanthos; Kofotolis, Nikolaos

    2016-01-01

    This study examined the use of ultrasound to monitor changes in the long head of the biceps femoris (BF) architecture of aprofessional soccer player with acute first-time hamstring strain. The player followed a 14 session physiotherapy treatment until return to sport. The pennation angle and aponeurosis strain of the long head of the biceps femoris (BF) were monitored at 6 occasions (up until 1 year) after injury. The size of the scar / hematoma was reduced by 63.56% (length) and 67.9% (width) after the intervention and it was almost non-traceable one year after injury. The pennation angle of the fascicles underneath the scar showed a decline of 51.4% at the end of the intervention while an increase of 109.2% of the fascicles which were closer to deep aponeurosis was observed. In contrast, pennation angle of fascicles located away from the injury site were relatively unaffected. The treatment intervention resulted in a 57.9% to 77.3% decline of maximum strain per unit of MVC moment and remained similar one year after the intervention. This study provided an example of the potential use of ultrasound-based parameters to link the mechanical adaptations of the injured muscle to specific therapeutic intervention. Key points Changes in fascicle orientation after biceps femoris mild tear were reduced after a 28 day intervention and remained similar one year after injury. Tendon/aponeurosis strain per unit of moment of force decreased during the course of the therapeutic intervention. Future studies could utilize ultrasonography to monitor mechanical responses after various types of hamstring injury and interventions in order to improve criteria for a safe return to sport. PMID:26957929

  3. Association of Quadriceps Strength and Psychosocial Factors With Single-Leg Hop Performance in Patients With Meniscectomy

    PubMed Central

    Hsu, Chao-Jung; George, Steven Z.; Chmielewski, Terese L.

    2016-01-01

    postrehabilitation, the peak knee flexion angle was positively associated with peak torque and RTD0-200ms, and the knee extension moment was positively associated with RTD0-200ms. At 1 year postsurgery, peak knee flexion angle and knee extension moment were both positively associated with peak torque, RTD0-200ms, and RTD0–peak torque. Conclusion: Although the hop symmetry index could be considered satisfactory for returning to sports, asymmetries in landing mechanics still exist in the first year postmeniscectomy. Greater quadriceps strength was associated with greater single-leg hop distance and better landing mechanics at both postrehabilitation and 1 year postsurgery. Knee activity self-efficacy was the only psychosocial factor associated with single-leg hop performance and isolated to a positive association with single-leg hop distance at postrehabilitation. Clinical Relevance: Rate of development is not typically measured in the clinic but can be an additional quadriceps measure to monitor for single-leg hop performance. Quadriceps strength and psychosocial factors appear to have separate influence on single-leg hop performance after meniscectomy, which has implications for developing appropriate interventions for optimal single-leg hop performance. PMID:28210647

  4. Persistent Neuromuscular and Corticomotor Quadriceps Asymmetry After Anterior Cruciate Ligament Reconstruction

    PubMed Central

    Kuenze, Christopher M.; Hertel, Jay; Weltman, Arthur; Diduch, David; Saliba, Susan A.; Hart, Joseph M.

    2015-01-01

    Context: Return to activity in the presence of quadriceps dysfunction may predispose individuals with anterior cruciate ligament reconstruction (ACLR) to long-term joint degeneration. Asymmetry may manifest during movement and result in altered knee-joint–loading patterns; however, the underlying neurophysiologic mechanisms remain unclear. Objective: To compare limb symmetry of quadriceps neuromuscular function between participants with ACLR and participants serving as healthy controls. Design: Descriptive laboratory study. Setting: Research laboratory. Patients or Other Participants: A total of 22 individuals with ACLR (12 men, 10 women) and 24 individuals serving as healthy controls (12 men, 12 women). Main Outcome Measure(s): Normalized knee-extension maximal voluntary isometric contraction (MVIC) torque (Nm/kg), quadriceps central activation ratio (CAR) (%), quadriceps motor-neuron–pool excitability (Hoffmann reflex to motor wave ratio), and quadriceps active motor threshold (AMT) (% 2.0 T) were measured bilaterally and used to calculate limb symmetry indices for comparison between groups. We used analyses of variance to compare quadriceps Hoffmann reflex to motor wave ratio, normalized knee-extension MVIC torque, quadriceps CAR, and quadriceps AMT between groups and limbs. Results: The ACLR group exhibited greater asymmetry in knee-extension MVIC torque (ACLR group = 0.85 ± 0.21, healthy group = 0.97 ± 0.14; t44 = 2.26, P = .03), quadriceps CAR (ACLR group = 0.94 ± 0.11, healthy group = 1.00 ± 0.08; t44 = 2.22, P = .04), and quadriceps AMT (ACLR group = 1.13 ± 0.18, healthy group = 1.02 ± 0.11; t34 = −2.46, P = .04) than the healthy control group. Conclusions: Asymmetries in measures of quadriceps function and cortical excitability were present in patients with ACLR. Asymmetry in quadriceps strength, activation, and cortical excitability persisted in individuals with ACLR beyond return to recreational activity. Measuring the magnitude of asymmetry

  5. Biomechanical Evaluation of Posterior Cruciate Ligament Reconstruction With Quadriceps Versus Achilles Tendon Bone Block Allograft

    PubMed Central

    Forsythe, Brian; Haro, Marc S.; Bogunovic, Ljiljana; Collins, Michael J.; Arns, Thomas A.; Trella, Katie J.; Shewman, Elizabeth F.; Verma, Nikhil N.; Bach, Bernard R.

    2016-01-01

    Background: Long-term studies of posterior cruciate ligament (PCL) reconstruction suggest that normal stability is not restored in the majority of patients. The Achilles tendon allograft is frequently utilized, although recently, the quadriceps tendon has been introduced as an alternative option due to its size and high patellar bone density. Purpose/Hypothesis: The purpose of this study was to compare the biomechanical strength of PCL reconstructions using a quadriceps versus an Achilles allograft. The hypothesis was that quadriceps bone block allograft has comparable mechanical properties to those of Achilles bone block allograft. Study Design: Controlled laboratory study. Methods: Twenty-nine fresh-frozen cadaveric knees were assigned to 1 of 3 groups: (1) intact PCL, (2) PCL reconstruction with Achilles tendon allograft, or (3) PCL reconstruction with quadriceps tendon allograft. After reconstruction, all supporting capsular and ligamentous tissues were removed. Posterior tibial translation was measured at neutral and 20° external rotation. Each specimen underwent a preload, 2 cyclic loading protocols of 500 cycles, then load to failure. Results: Construct creep deformation was significantly lower in the intact group compared with both Achilles and quadriceps allograft (P = .008). The intact specimens reached the greatest ultimate load compared with both reconstructions (1974 ± 752 N, P = .0001). The difference in ultimate load for quadriceps versus Achilles allograft was significant (P = .048), with the quadriceps group having greater maximum force during failure testing. No significant differences were noted between quadriceps versus Achilles allograft for differences in crosshead excursion during cyclic testing (peak-valley [P-V] extension stretch), creep deformation, or stiffness. Construct stiffness measured during the failure test was greatest in the intact group (117 ± 9 N/mm, P = .0001) compared with the Achilles (43 ± 11 N/mm) and quadriceps (43

  6. Quadriceps Strength, Muscle Activation Failure, and Patient-Reported Function at the Time of Return to Activity in Patients Following Anterior Cruciate Ligament Reconstruction: A Cross-sectional Study

    PubMed Central

    Lepley, Lindsey K.; Palmieri-Smith, Riann M.

    2016-01-01

    Study Design Cross-sectional. Objectives To determine if quadriceps activation failure (QAF) moderates the relationship between quadriceps strength and physical function in individuals post-anterior cruciate ligament (ACL) reconstruction. Background QAF may impair the recovery of physical function post ACL reconstruction, given that QAF reduces strength, and strength is related to physical function. Evidence of this relationship has been found in individuals with knee osteoarthritis, wherein patients with lower strength and greater QAF had lower levels of physical function. Methods Participants consisted of 52 individuals who were cleared for return to activity at an average ± SD of 7.4 ± 1.2 months post ACL reconstruction. QAF was assessed using the superimposed burst technique and quadriceps strength was assessed using concentric isokinetic contractions (Nm/kg). Physical function was quantified using a combined variable of physical (single leg hop for distance) and self-reported function (International Knee Documentation Committee form) calculated using a principal component analysis (PCPF). Simple correlations were then performed to determine the order in which variables were entered into the regression model to evaluate if QAF moderates the relationship between quadriceps strength and physical function. Results The combination of quadriceps strength and the interaction of strength-by-QAF predicted 30% of the variance in physical function (R2=0.30, P<.001; PCPF = -0.61strength + 0.20interaction - 1.896); however the interaction of strength-by-QAF only accounted for 7% of the capabilities of the model (P=.023). Conclusion Physical function is largely influenced by the recovery of quadriceps strength and minimally attenuated by QAF. These data suggest that QAF may affect individuals post ACL reconstruction differently, and to a lesser extent, than knee individuals with knee osteoarthritis. PMID:26471854

  7. Percutaneous quadriceps tendon pie-crusting release of extension contracture of the knee.

    PubMed

    Liu, H X; Wen, H; Hu, Y Z; Yu, H C; Pan, X Y

    2014-05-01

    To release extension contracture of the knee, the authors used a minimally invasive technique: percutaneous quadriceps tendon pie-crusting release. Percutaneous pie-crusting release was performed using an 18-gauge needle to puncture the stiff fibrous band of the distal and lateral quadriceps tendon under maximum knee flexion. Quadriceps contracture was gradually released by multiple needle punctures. A knee brace was prescribed for one week and knee flexion exercises were performed on the first postoperative day. This technique was performed in seven post-traumatic stiff knees and five stiff total knee arthroplasties. Mean maximum flexion increased from 37° preoperatively to 50° after arthrolysis and 107(o) after pie-crusting. At a mean follow-up of eight months, mean maximum flexion was 103°. There were no major complications. The technique of quadriceps tendon pie-crusting release is a simple, minimally invasive and effective treatment for knee extension contracture.

  8. The force-length curves of the human rectus femoris and gastrocnemius muscles in vivo.

    PubMed

    Winter, Samantha L; Challis, John H

    2010-02-01

    For a physiologically realistic joint range of motion and therefore range of muscle fiber lengths, only part of the whole muscle force-length curve can be used in vivo; that is, only a section of the force-length curve is expressed. Previous work has determined that the expressed section of the force-length curve for individual muscles can vary between subjects; however, the degree of intersubject variability is different for different muscles. This study determined the expressed section of both the rectus femoris and gastrocnemius--muscles with very different ratios of tendon slack length to muscle fiber optimum length--for 28 nonspecifically trained subjects to test the hypothesis that the value of this ratio affects the amount of variability in the expressed section. The force-length curves of the two muscles were reconstructed from moment-angle data using the method of Herzog & ter Keurs (1988). There was no relationship between the expressed sections of the force-length curve for the two muscles. Less variability was found in the expressed section of the gastrocnemius compared with the rectus femoris, supporting the hypothesis. The lack of relationship between the expressed sections of the two muscles has implications for motor control and for training muscle for rehabilitation.

  9. Variability of Measurement of Patellofemoral Indices with Knee Flexion and Quadriceps Contraction: An MRI-Based Anatomical Study

    PubMed Central

    Laugharne, Edward; Bali, Navi; Purushothamdas, Sanjay; Almallah, Faris; Kundra, Rik

    2016-01-01

    Purpose The purpose of this study was to investigate the impact of varying knee flexion and quadriceps activity on patellofemoral indices measured on magnetic resonance imaging (MRI). Materials and Methods MRI of the knee was performed in 20 patients for indications other than patellar or patellofemoral pathology. Axial and sagittal sequences were performed in full extension of the knee with the quadriceps relaxed, full extension of the knee with the quadriceps contracted, 30° flexion of the knee with the quadriceps relaxed, and 30° flexion with the quadriceps contracted. Bisect offset, patella tilt angle, Insall-Salvati ratio and Caton-Deschamps index were measured. Results With the knee flexed to 30° and quadriceps relaxed, the mean values of patellar tilt angle, bisect offset, Insall-Salvati ratio and Caton-Deschamps index were all within normal limits. With the knee extended and quadriceps contracted, the mean patellar tilt angle (normal value, <15°) was 14.6° and the bisect offset (normal value, <65%) was 65%, while the Caton-Deschamps index was 1.34 (normal range, 0.6 to 1.3). With the knee extended and quadriceps relaxed, the mean Caton-Deschamps index was 1.31. Conclusions MRI scanning of the knee in extension with the quadriceps contracted leads to elevated patellofemoral indices. MRI taken with the knee in 30° of flexion allows more reliable assessment of the patellofemoral joint and minimises the confounding effect of quadriceps contraction. PMID:27894177

  10. Effect of knee angle on quadriceps strength and activation after anterior cruciate ligament reconstruction

    PubMed Central

    Theuerkauf, Paul

    2015-01-01

    Quadriceps strength and activation deficits after anterior cruciate ligament (ACL) injury or surgery are typically evaluated at joint positions that are biomechanically advantageous to the quadriceps muscle. However, the effect of knee joint position and the associated changes in muscle length on strength and activation is currently unknown in this population. Here, we examined the effect of knee angle on quadriceps strength, activation, and electrically evoked torque in individuals with ACL reconstruction. Furthermore, we evaluated whether knee angle mediated the relationship between quadriceps weakness and functional performance after ACL reconstruction. Knee strength and activation were tested bilaterally at 90° and 45° of knee flexion in 11 subjects with ACL reconstruction using an interpolated triplet technique. The magnitude of electrically evoked torque at rest was used to quantify peripheral muscle contractile property changes, and the single-leg hop for distance test was used to evaluate functional performance. The results indicated that although quadriceps strength deficits were similar between knee angles, voluntary activation deficits were significantly higher in the reconstructed leg at 45° of knee flexion. On the contrary, the side-to-side evoked torque at rest ratio [i.e., (reconstructed/nonreconstructed) × 100] was significantly lower at 90° than at 45° of knee flexion. The association between quadriceps strength and functional performance was stronger at 45° of knee flexion. The results provide novel evidence that quadriceps activation is selectively affected at 45° of knee flexion and emphasize the importance of assessing quadriceps strength and activation at this position when feasible because it better captures activation deficits. PMID:25997949

  11. Combination of Eccentric Exercise and Neuromuscular Electrical Stimulation to Improve Quadriceps Function Post-ACL Reconstruction

    PubMed Central

    Lepley, Lindsey K.; Wojtys, Edward M.; Palmieri-Smith, Riann M.

    2014-01-01

    Background Neuromuscular electrical stimulation (NMES) has been shown to reduce quadriceps activation failure (QAF), and eccentric exercise has been shown lessen muscle atrophy post-ACL reconstruction. Given that these are two critical components of quadriceps strength, intervention combining these therapies may be effective at reinstituting quadriceps function post-anterior cruciate ligament (ACL) reconstruction. Objectives To evaluate the effectiveness of a combined NMES and eccentric exercise intervention to improve the recovery of quadriceps activation and strength post-reconstruction. Design Parallel longitudinal design. Setting Laboratory. Participants Thirty-six individuals post-injury were placed into four treatment groups (N&E, NMES and eccentrics; E-only, eccentrics only; N-only, NMES-only; STND, standard of care) and ten healthy controls participated. Intervention N&E and N-only received the NMES protocol 2x per week for the first six weeks post-reconstruction. N&E and E-only received the eccentric exercise protocol 2x per week beginning six weeks post-reconstruction. Main outcome measure Quadriceps activation was assessed via the superimposed burst technique and quantified via the central activation ratio. Quadriceps strength was assessed via maximal voluntary isomeric contractions (Nm/kg). Data was gathered on three occasions: pre-operative, 12-weeks-post-surgery and at return-to-play. Results No differences in pre-operative measures existed (P>0.05). E-only recovered quadriceps activation better than N-only or STND (P<0.05). N&E and E-only recovered strength better than N-only or the STND (P<0.05) and had strength values that were similar to healthy individuals at return-to-play (P>0.05). Conclusion Eccentric exercise was capable of restoring levels of quadriceps activation and strength that were similar to those of healthy adults and better than NMES alone. PMID:25819154

  12. Quadriceps tendon allografts as an alternative to Achilles tendon allografts: a biomechanical comparison.

    PubMed

    Mabe, Isaac; Hunter, Shawn

    2014-12-01

    Quadriceps tendon with a patellar bone block may be a viable alternative to Achilles tendon for anterior cruciate ligament reconstruction (ACL-R) if it is, at a minimum, a biomechanically equivalent graft. The objective of this study was to directly compare the biomechanical properties of quadriceps tendon and Achilles tendon allografts. Quadriceps and Achilles tendon pairs from nine research-consented donors were tested. All specimens were processed to reduce bioburden and terminally sterilized by gamma irradiation. Specimens were subjected to a three phase uniaxial tension test performed in a custom environmental chamber to maintain the specimens at a physiologic temperature (37 ± 2 °C) and misted with a 0.9 % NaCl solution. There were no statistical differences in seven of eight structural and mechanical between the two tendon types. Quadriceps tendons exhibited a significantly higher displacement at maximum load and significantly lower stiffness than Achilles tendons. The results of this study indicated a biomechanical equivalence of aseptically processed, terminally sterilized quadriceps tendon grafts with bone block to Achilles tendon grafts with bone block. The significantly higher displacement at maximum load, and lower stiffness observed for quadriceps tendons may be related to the failure mode. Achilles tendons had a higher bone avulsion rate than quadriceps tendons (86 % compared to 12 %, respectively). This was likely due to observed differences in bone block density between the two tendon types. This research supports the use of quadriceps tendon allografts in lieu of Achilles tendon allografts for ACL-R.

  13. Effects of Kinesiology Taping on Repositioning Error of the Knee Joint after Quadriceps Muscle Fatigue

    PubMed Central

    Han, Jin Tae; Lee, Jung-hoon

    2014-01-01

    [Purpose] The purpose of this study was to identify the effects of kinesiology taping on repositioning error of the knee joint after quadriceps muscle fatigue. [Subjects] Thirty healthy adults with no orthopaedic or neurological problems participated in this study. [Methods] The repositioning error of the knee joint was measured using a digital goniometer when the subjects extended their dominant-side knee to a random target angle (30°, 45°, or 60°) with their eyes closed, before and after a quadriceps muscle fatigue protocol, and after application of kinesiology tape. [Results] We found that repositioning errors of the dominant-side knee joint increased after quadriceps fatigue compared with no-fatigue conditions. However, kinesiology taping of the quadriceps muscle and patella after quadriceps fatigue significantly decreased repositioning errors of the knee joint. [Conclusion] These results suggest that quadriceps fatigue increases the repositioning error of the knee joint, whereas application of kinesiology tape decreases fatigue-induced joint repositioning error. PMID:25013297

  14. Corticospinal and Intracortical Excitability of the Quadriceps in Patients with Knee Osteoarthritis

    PubMed Central

    Kittelson, Andrew J.; Thomas, Abbey C.; Kluger, Benzi M.; Stevens-Lapsley, Jennifer E.

    2015-01-01

    Deficits in voluntary activation of the quadriceps muscle are characteristic of knee osteoarthritis (OA), contributing to the quadriceps weakness that is also a hallmark of the disease. The mechanisms underlying this central activation deficit (CAD) are unknown, although cortical mechanisms may be involved. Here, we utilize transcranial magnetic stimulation (TMS) to assess corticospinal and intracortical excitability in patients with knee osteoarthritis (OA) and in a comparably aged group of healthy older adults, to quantify group differences and to examine associations between TMS measures and pain, quadriceps strength, and CAD. Seventeen patients with knee OA and 20 healthy controls completed testing. Motor evoked potentials (MEPs) were measured at the quadriceps by superficial electromyographic (EMG) recordings. Corticospinal excitability was assessed by measuring resting motor threshold (RMT) to TMS stimulation of the quadriceps representation at primary motor cortex, and intracortical excitability was assessed via paired pulse paradigms for short interval intracortical inhibition (SICI) and intracortical facilitation (ICF). No statistically significant differences between patients with knee OA and healthy controls were found for RMT, SICI or ICF measures (p>0.05). For patients with knee OA, there were significant associations observed between pain and RMT, as well as between pain and ICF. No associations were observed between CAD and measures of corticospinal or intracortical excitability. These data suggest against direct involvement of corticospinal or intracortical pathways within primary motor cortex in the mechanisms of CAD. However, pain is implicated in the neural mechanisms of quadriceps motor control in patients with knee OA. PMID:25183161

  15. Correlation between Quadriceps Endurance and Adduction Moment in Medial Knee Osteoarthritis

    PubMed Central

    Ahn, Sung-Eun; Park, Min-Ji; Lee, Dae-Hee

    2015-01-01

    It is not clear whether the strength or endurance of thigh muscles (quadriceps and hamstring) is positively or negatively correlated with the adduction moment of osteoarthritic knees. This study therefore assessed the relationships between the strength and endurance of the quadriceps and hamstring muscles and adduction moment in osteoarthritic knees and evaluated predictors of the adduction moment. The study cohort comprised 35 patients with unilateral medial osteoarthritis and varus deformity who were candidates for open wedge osteotomy. The maximal torque (60°/sec) and total work (180°/sec) of the quadriceps and hamstring muscles and knee adduction moment were evaluated using an isokinetic testing device and gait analysis system. The total work of the quadriceps (r = 0.429, P = 0.037) and hamstring (r = 0.426, P = 0.045) muscles at 180°/sec each correlated with knee adduction moment. Preoperative varus deformity was positively correlated with adduction moment (r = 0.421, P = 0.041). Multiple linear regression analysis showed that quadriceps endurance at 180°/sec was the only factor independently associated with adduction moment (β = 0.790, P = 0.032). The adduction moment of osteoarthritic knees correlated with the endurance, but not the strength, of the quadriceps muscle. However, knee adduction moment did not correlate with the strength or endurance of the hamstring muscle. PMID:26539830

  16. Facilitation of quadriceps activation is impaired following eccentric exercise.

    PubMed

    Hedayatpour, N; Arendt-Nielsen, L; Falla, D

    2014-04-01

    Contracting the knee flexor muscles immediately before a maximum voluntary contraction (MVC) of knee extension increases the maximal force that the extensor muscles can exert. It is hypothesized that this phenomenon can be impaired by muscle fiber damage following eccentric exercise [delayed onset muscle soreness (DOMS)]. This study investigates the effect of eccentric exercise and DOMS on knee extension MVC immediately following a reciprocal-resisted knee flexion contraction. Electromyography (EMG) was recorded from the knee extensors and flexors of 12 healthy men during knee extension MVCs performed in a reciprocal (maximal knee extension preceded by resisted knee flexion), and nonreciprocal condition (preceded by relaxation of the knee flexors). At baseline, knee extension MVC force was greater during the reciprocal condition (P < 0.001), whereas immediately after, 24 and 48 h after eccentric exercise, the MVC force was not different between conditions. Similarly, at baseline, the EMG amplitude of the quadriceps during the MVC was larger for the reciprocal condition (P < 0.001). However, immediately after, 24 and 48 h postexercise the EMG amplitude was similar between conditions. In conclusion, eccentric exercise abolished the facilitation of force production for the knee extensors, which normally occurs when maximum knee extension is preceded by activation of the knee flexors.

  17. Sex differences in function and structure of the quadriceps muscle in chronic obstructive pulmonary disease patients.

    PubMed

    Ausín, Pilar; Martínez-Llorens, Juana; Sabaté-Bresco, Marina; Casadevall, Carme; Barreiro, Esther; Gea, Joaquim

    2016-12-06

    Chronic obstructive pulmonary disease (COPD) is a complex disorder with extrapulmonary manifestations. Even though there is some knowledge regarding sex differences in the lung disease, little is known about extrapulmonary manifestations. Our aim was to analyze the specific profile of muscle dysfunction, structure, and biology in COPD women. Twenty-one women and 19 men with stable COPD as well as 15 controls were included. Nutritional status, physical activity, lung and muscle function, exercise capacity, and quality of life were assessed. In addition, blood, breath condensate, and quadriceps muscle samples were tested for inflammatory markers. Moreover, fiber phenotype, signs of damage-regeneration, and the expression of key genes linked to myogenesis and inflammation were assessed in the muscle. Inflammatory markers were increased in all body compartments but no correlation was found among them. Muscle dysfunction was present in both COPD groups but was more marked in women. The opposite occurred with the increase in the percentage of type II fibers that was lower in women despite a similar level of airway obstruction as in men. Female COPD also showed higher signs of muscle damage than COPD men who, in contrast, exhibited slightly higher signs of regeneration. We conclude that sex influences muscle phenotype and function in COPD.

  18. Use of MMG signals for the control of powered orthotic devices: development of a rectus femoris measurement protocol.

    PubMed

    Antonelli, Michele Gabrio; Zobel, P Beomonte; Giacomin, J

    2009-01-01

    A test protocol is defined for the purpose of measuring rectus femoris mechanomyographic (MMG) signals. The protocol is specified in terms of the following: measurement equipment, signal processing requirements, human postural requirements, test rig, sensor placement, sensor dermal fixation, and test procedure. Preliminary tests of the statistical nature of rectus femoris MMG signals were performed, and Gaussianity was evaluated by means of a two-sided Kolmogorov-Smirnov test. For all 100 MMG data sets obtained from the testing of two volunteers, the null hypothesis of Gaussianity was rejected at the 1%, 5%, and 10% significance levels. Most skewness values were found to be greater than 0.0, while all kurtosis values were found to be greater than 3.0. A statistical convergence analysis also performed on the same 100 MMG data sets suggested that 25 MMG acquisitions should prove sufficient to statistically characterize rectus femoris MMG. This conclusion is supported by the qualitative characteristics of the mean rectus femoris MMG power spectral densities obtained using 25 averages.

  19. Relationships between Muscle Architecture of Rectus Femoris and Functional Parameters of Knee Motion in Adults with Down Syndrome

    PubMed Central

    Micale, Marco; Cioni, Matteo

    2016-01-01

    This study was designed to measure in vivo muscle architecture of the rectus femoris in adults with Down syndrome, testing possible relationships with functional parameters of the knee motion. Ten adults with Down syndrome and ten typically developed participated in the study. Pennation angle and thickness of the rectus femoris and subcutaneous layer of the thigh were measured via ultrasound imaging. Knee kinematics and electromyographic activity of the rectus femoris were recorded during free leg dropping. Muscle thickness was reduced and subcutaneous layer was thicker in persons with Down syndrome with respect to typically developed adults, but there were no differences in the pennation angle. The area of the rectus femoris EMG activity during the leg flexion was greater in Down syndrome with respect to typically developed adults. The leg movement velocity was lower in Down people than in controls, but the knee excursion was similar between the groups. Functional parameters correlated with pennation angle in the persons with Down syndrome and with muscle thickness in typically developed persons. The description of muscle architecture and the relationships between morphological and functional parameters may provide insights on the limits and the opportunities to overcome the inherent biomechanical instability in Down syndrome. PMID:27896273

  20. Relationships between Muscle Architecture of Rectus Femoris and Functional Parameters of Knee Motion in Adults with Down Syndrome.

    PubMed

    Valle, Maria Stella; Casabona, Antonino; Micale, Marco; Cioni, Matteo

    2016-01-01

    This study was designed to measure in vivo muscle architecture of the rectus femoris in adults with Down syndrome, testing possible relationships with functional parameters of the knee motion. Ten adults with Down syndrome and ten typically developed participated in the study. Pennation angle and thickness of the rectus femoris and subcutaneous layer of the thigh were measured via ultrasound imaging. Knee kinematics and electromyographic activity of the rectus femoris were recorded during free leg dropping. Muscle thickness was reduced and subcutaneous layer was thicker in persons with Down syndrome with respect to typically developed adults, but there were no differences in the pennation angle. The area of the rectus femoris EMG activity during the leg flexion was greater in Down syndrome with respect to typically developed adults. The leg movement velocity was lower in Down people than in controls, but the knee excursion was similar between the groups. Functional parameters correlated with pennation angle in the persons with Down syndrome and with muscle thickness in typically developed persons. The description of muscle architecture and the relationships between morphological and functional parameters may provide insights on the limits and the opportunities to overcome the inherent biomechanical instability in Down syndrome.

  1. Initial experience with proximal ligation for profunda femoris artery aneurysms: report of three cases.

    PubMed

    Shintani, Tsunehiro; Norimatsu, Togo; Atsuta, Koji; Saitou, Takaaki; Higashi, Shigeki; Mitsuoka, Hiroshi

    2014-04-01

    Profunda femoris artery aneurysms (PFAAs) are rare and difficult to diagnose in the early stage. They are often found due to the presence of complicated conditions, such as rapid expansion, rupture, or acute lower limb ischemia. Surgical procedures such as aneurysmectomy and endoaneurysmorrhaphy tend to be technically challenging because of the patient status and the extent of the aneurysm. We experienced three cases of PFAAs that were treated by proximal ligation (PL) without complete control of the distal branches. The exclusion of PFAAs was confirmed by duplex ultrasound or angiography at the end of the operation. There was no mortality in the perioperative period. During a 12-month follow-up, all cases exhibited complete exclusion of aneurysms with marked size reduction. Based on these findings, we propose that PL, with a careful follow-up for PFAA exclusion and distal limb circulation, could be an alternative treatment for complicated PFAAs.

  2. The ligamentum capitis femoris: anatomic, magnetic resonance and computed tomography study.

    PubMed

    Perez-Carro, Luis; Golano, Pau; Vega, Jordi; Escajadillo, Natalia F; Rubin, Carlos G; Cerezal, Luis

    2011-01-01

    The objective of the study was to describe the normal anatomy of the ligamentum capitis femoris and to determine the neurovascular structures potentially at risk during its reconstruction. Ten cadaveric specimens of the ligamentum capitis femoris (LCF) were dissected and photographed. Magnetic resonance (MR) and Computed tomography (CT) arthrography evaluation of the anatomy of the LCF in 30 hips were performed to measure length of the ligament and to study the proximity of neurovascular structures. The anatomical study showed that the LCF has a pyramidal structure and a banded appearance. The thickness of the medial wall of the acetabulum 3 mm superior to the inferior acetabular boundary was found to be 6.7 mm (4-9 mm) at point 1 (anterior), 4.1 mm (3-7 mm) at point 2 (central), and 6.5 mm (4-9 mm) at point 3 (posterior). Central anchors or screws were found to lie within 1.7 cm (1.6-1.9 cm) of the external iliac vein and artery. Angulation of anchors in the anterior and posterior columns in the axial plane with respect to acetabular fossa floor (the Optimal Angulation Angle or OAA), is safer (0 to 45º the safest optimal angles). The sagittal angulation created by the safe pathway in the anterior and posterior columns with respect to the plane of the facies lunata in this area was also measured and termed the Optimal Angle of Penetration (OAP) with normal values being: 110º (102-123º) for the posterior column and 90º (85-94º) for the anterior column. Our results suggest that reconstruction of the LCF can be safely performed if these guidelines are followed.

  3. Quadriceps and hamstrings fatigue alters hip and knee mechanics.

    PubMed

    Thomas, Abbey C; McLean, Scott G; Palmieri-Smith, Riann M

    2010-05-01

    Neuromuscular fatigue exacerbates abnormal landing strategies, which may increase noncontact anterior cruciate ligament (ACL) injury risk. The synergistic actions of quadriceps and hamstrings (QH) muscles are central to an upright landing posture, though the precise effect of simultaneous fatigue of these muscles on landing and ACL injury risk is unclear. Elucidating neuromechanical responses to QH fatigue thus appears important in developing more targeted fatigue-resistance intervention strategies. The current study thus aimed to examine the effects of QH fatigue on lower extremity neuromechanics during dynamic activity. Twenty-five healthy male and female volunteers performed three single-leg forward hops onto a force platform before and after QH fatigue. Fatigue was induced through sets of alternating QH concentric contractions, on an isokinetic dynamometer, until the first five repetitions of a set were performed at least 50% below QH peak torque. Three-dimensional hip and knee kinematics and normalized (body mass x height) kinetic variables were quantified for pre- and postfatigue landings and subsequently analyzed by way of repeated- measures mixed-model ANOVAs. QH fatigue produced significant increases in initial contact (IC) hip internal rotation and knee extension and external rotation angles (p < .05), with the increases in knee extension and external rotation being maintained at the time of peak vertical ground reaction force (vGRF) (p < .05). Larger knee extension and smaller knee flexion and external rotation moments were also evident at peak vGRF following fatigue (p < .05). Females landed with greater hip flexion and less abduction than males at both IC and peak vGRF as well as greater knee flexion at peak vGRF (p < .05). The peak vGRF was larger for females than males (p < .05). No sex x fatigue effects were found (p > .05). Fatigue of the QH muscles altered hip and knee neuromechanics, which may increase the risk of ACL injury. Prevention programs

  4. Interplay between body stabilisation and quadriceps muscle activation capacity.

    PubMed

    Bampouras, Theodoros M; Reeves, Neil D; Baltzopoulos, Vasilios; Maganaris, Constantinos N

    2017-03-22

    The study aimed to distinguish the effect of stabilisation and muscle activation on quadriceps maximal isometric voluntary contraction (MVC) torque generation. Nine subjects performed (a) an MVC with restrained leg and pelvis (Typical MVC), (b) a Typical MVC with handgrip (Handgrip MVC), (c) an MVC focusing on contracting the knee extensors only (Isolated knee extension MVC), and (d) an MVC with unrestrained leg and pelvis (Unrestrained MVC). Torque and activation capacity between conditions were compared with repeated measures ANOVA and dependent t-tests. EMG (from eleven remote muscles) was compared using Friedman's and Wilcoxon. Typical MVC (277.2±49.6Nm) and Handgrip MVC (261.0±55.4Nm) were higher than Isolated knee extension MVC (210.2±48.3Nm, p<0.05) and Unrestrained MVC (195.2±49.7Nm, p<0.05) torque. Typical MVC (83.1±15.9%) activation was higher than Isolated knee extension MVC (68.9±24.3%, p<0.05), and both Typical MVC and Handgrip MVC (81.8±17.4%) were higher than Unrestrained MVC (64.9±16.2%, p<0.05). Only flexor carpi radialis, biceps brachii, triceps brachii and external oblique muscles showed EMG differences, with Isolated knee extension MVC consistently lower than Typical MVC or Handgrip MVC. Stabilisation of the involved segments is the prime concern allowing fuller activation of the muscle, reinforcing the need for close attention to stabilisation during dynamometry-based knee joint functional assessment.

  5. Measurement of quadriceps endurance by fNIRS

    NASA Astrophysics Data System (ADS)

    Erdem, Devrim; Şayli, Ömer; Karahan, Mustafa; Akin, A.

    2006-02-01

    In this paper, the changes in muscle deoxygenation trends during a sustained isometric quadriceps (chair squat/half squat) endurance exercise were evaluated among twelve male subjects and the relationship between muscle oxygenation and endurance times was investigated by means of functional near-infrared spectroscopy (fNIRS). Neuromuscular activation and predictions of muscle performance decrements during extended fatiguing task was investigated by means of surface electromyography (sEMG). The results of the study showed that in the subjects who maintained exercise longer than five minutes (group 1), mean Hb recovery time (33 [sec.]) was 37.4% less than the others (group 2, 52.7 [sec.]). Also mean HbO II decline amplitude (2.53 [a.u.] in group 1 and 2.07 [a.u.] in group 2) and oxy decline amplitude (8.4 [a.u.] in group 1 and 3.04 [a.u.] in group 2) in the beginning of squat exercise are found to be 22.6% and 176.9% bigger in these group. For the EMG parameters, mean slope of MNF and MDF decline are found to be 57.5% and 42.2% bigger in magnitude in group 2 which indicates higher degree of decrement in mean and median frequencies although their mean squat duration time is less. This indicates higher index of fatigue for this group. It is concluded that training leads to altered oxygenation and oxygen extraction capability in the exercising muscle and investigated fNIRS parameters could be used for endurance evaluation.

  6. Decrease in eccentric quadriceps and hamstring strength in recreational alpine skiers after prolonged skiing

    PubMed Central

    Koller, Arnold; Fuchs, Birgit; Leichtfried, Veronika; Schobersberger, Wolfgang

    2015-01-01

    Background To effectively prevent injury in recreational alpine skiing, it is important to identify modifiable risk factors that can be targeted through exercise and training. Fatigue is a potential risk factor in recreational skiing, but no investigations have evaluated concentric/eccentric quadriceps and hamstring fatigue in recreational skiers. We tested the hypothesis that recreational skiing is associated with more pronounced eccentric as compared with concentric muscle fatigue. Methods Twenty-four healthy and fit recreational skiers (14 male and 10 female) performed an isokinetic muscle test 1 day before, 1 h after, and 24 h after a 4 h skiing session. The testing protocol consisted of concentric and eccentric quadriceps and hamstring contractions for both legs. Results Eccentric peak hamstring torque (both thighs) and eccentric peak quadriceps torque (left thigh) were reduced in male and female participants (p<0.05). Reduced peak torques were still present 24 h after the skiing session. There were no other significant findings. Summary Recreational skiing is associated with prolonged (at least 24 h) eccentric quadriceps (left thigh) and hamstring (both thighs) fatigue in men and women. Eccentric quadriceps and hamstring fatigue may be a potential injury risk factor in male and female recreational skiers. This provides some justification for judicious use of additional eccentric training modalities for alpine skiing. PMID:27900115

  7. Quadriceps Strength Asymmetry Following ACL Reconstruction Alters Knee Joint Biomechanics and Functional Performance at Time of Return to Activity

    PubMed Central

    Palmieri-Smith, RM; Lepley, LK

    2016-01-01

    Background Quadriceps strength deficits are observed clinically following anterior cruciate injury and reconstruction and are often not overcome despite rehabilitation. Given that quadriceps strength may be important for achieving symmetrical joint biomechanics and promoting long-term joint health, determining the magnitude of strength deficits that lead to altered mechanics is critical. Purpose To determine if the magnitude of quadriceps strength asymmetry alters knee and hip biomechanical symmetry, as well as functional performance and self-reported function. Study Design Cross-Sectional study. Methods Seventy-three patients were tested at the time they were cleared for return to activity following ACL reconstruction. Quadriceps strength and activation, scores on the International Knee Documentation Committee form, the hop for distance test, and sagittal plane lower extremity biomechanics were recorded while patients completed a single-legged hop. Results Patients with high and moderate quadriceps strength symmetry had larger central activation ratios as well as greater limb symmetry indices on the hop for distance compared to patients with low quadriceps strength symmetry (P<0.05). Similarly, knee flexion angle and external moment symmetry was higher in the patients with high and moderate quadriceps symmetry compared to those with low symmetry (P<0.05). Quadriceps strength was found to be associated with sagittal plane knee angle and moment symmetry (P<0.05). Conclusion Patients with low quadriceps strength displayed greater movement asymmetries at the knee in the sagittal plane. Quadriceps strength was related to movement asymmetries and functional performance. Rehabilitation following ACL reconstruction needs to focus on maximizing quadriceps strength, which likely will lead to more symmetrical knee biomechanics. PMID:25883169

  8. Redox balance following magnetic stimulation training in the quadriceps of patients with severe COPD.

    PubMed

    Bustamante, Víctor; Casanova, Juan; López de Santamaría, Elena; Mas, Sandra; Sellarés, Jacobo; Gea, Joaquim; Gáldiz, Juan B; Barreiro, Esther

    2008-11-01

    In severe COPD patients, oxidative stress, which is involved in their peripheral muscle dysfunction, increases in response to exercise. In this study, muscle oxidative stress was explored after quadriceps magnetic stimulation training. A randomized controlled study was conducted on very severe COPD patients, who underwent quadriceps magnetic stimulation training for 8 weeks. A control group was also studied. In both groups, vastus lateralis specimens were obtained before and after the 8-week period. Muscle protein carbonylation and nitration and antioxidant enzymes were determined using immunoblotting and proportions and sizes of type I and II fibres using immunohistochemistry. Compared to controls, magnetic stimulation muscle training did not modify redox balance, whilst inducing a significant increase in type I fibre sizes. In severe COPD patients, it is concluded that quadriceps magnetic stimulation training was a well-tolerated therapeutic intervention, which did not enhance muscle oxidative stress, while increasing the size of slow-twitch fibres.

  9. Simultaneous Bilateral Quadriceps Tendon Rupture following Long-Term Low-Dose Nasal Corticosteroid Application

    PubMed Central

    Ettinger, Max; Krettek, Christian

    2013-01-01

    Simultaneous bilateral quadriceps tendon rupture is a very rare injury, which was previously only described in slightly more than 100 cases in the English literature. Occurrence after minor trauma is predominantly associated with certain medical conditions including chronic diseases and long-term use of certain drugs. We report the case of a 61-year-old healthy patient who sustained a simultaneous bilateral quadriceps tendon rupture following minor trauma. Medical history was completely clear except of a long-term nasal corticosteroid medication due to allergic rhinitis. PMID:23984143

  10. Skeletal muscle alterations in chronic heart failure: differential effects on quadriceps and diaphragm

    PubMed Central

    Mangner, Norman; Weikert, Bettina; Bowen, T Scott; Sandri, Marcus; Höllriegel, Robert; Erbs, Sandra; Hambrecht, Rainer; Schuler, Gerhard; Linke, Axel; Gielen, Stephan; Adams, Volker

    2015-01-01

    Background Chronic heart failure (CHF) results in limb and respiratory muscle weakness, which contributes to exercise intolerance and increased morbidity and mortality, yet the molecular mechanisms remain poorly understood. Therefore, we aimed to compare parameters of antioxidative capacity, energy metabolism, and catabolic/anabolic balance in diaphragm and quadriceps muscle in an animal model of CHF. Methods Ligation of the left anterior descending coronary artery (n = 13) or sham operation (n = 11) was performed on Wistar Kyoto rats. After 12 weeks, echocardiography and invasive determination of maximal rates of left ventricular (LV) pressure change were performed. Antioxidative and metabolic enzyme activities and expression of catabolic/anabolic markers were assessed in quadriceps and diaphragm muscle. Results Ligated rats developed CHF (i.e. severe LV dilatation, reduced LV ejection fraction, and impaired maximal rates of LV pressure change; P < 0.001). There was a divergent response for antioxidant enzymes between the diaphragm and quadriceps in CHF rats, with glutathione peroxidase and manganese superoxide dismutase activity increased in the diaphragm but reduced in the quadriceps relative to shams (P < 0.01). Metabolic enzymes were unaltered in the diaphragm, but cytochrome c oxidase activity (P < 0.01) decreased and lactate dehydrogenase activity (P < 0.05) increased in the quadriceps of CHF animals. Protein expression of the E3 ligase muscle ring finger 1 and proteasome activity were increased (P < 0.05) in both the diaphragm and quadriceps in CHF rats compared with shams. Conclusion Chronic heart failure induced divergent antioxidative and metabolic but similar catabolic responses between the diaphragm and quadriceps. Despite the quadriceps demonstrating significant impairments in CHF, apparent beneficial adaptations of an increased antioxidative capacity were induced in the diaphragm. Nevertheless, muscle ring finger 1 and

  11. “Central” Quadriceps Tendon Harvest With Patellar Bone Plug: Surgical Technique Revisited

    PubMed Central

    Scully, William F.; Wilson, David J.; Arrington, Edward D.

    2013-01-01

    The objective of this article is to review the surgical technique for quadriceps tendon graft harvest while highlighting an additional technical note that has not been previously emphasized. The quadriceps tendon typically inserts eccentrically on the superior pole of the patella. By shifting the soft-tissue harvest to a location just off the medial edge of the tendon, the adjoining patellar bone plug will be centered on the superior pole of the patella, reducing the risk of an iatrogenic patellar fracture. PMID:24400194

  12. The relationship between shear force, compression, collagen characteristics, desmin degradation and sarcomere length in lamb biceps femoris.

    PubMed

    Starkey, Colin P; Geesink, Geert H; van de Ven, Remy; Hopkins, David L

    2017-04-01

    This study aimed to identity the relationships between known variants of tenderness (collagen content (total and soluble), desmin degradation and sarcomere length) and shear force and compression in the biceps femoris aged for 14days from 112 mixed sex lambs. Desmin degradation was related to compression (P<0.05) such that as desmin degradation increased compression decreased. Sarcomere length (SL) was related to shear force (P<0.05), such that as SL increased shear force declined. Shear force was also related to compression (P<0.05), and soluble collagen (P<0.05), with male lambs producing higher shear force values than females (4.4±1.72N: P<0.05) when adjusted for compression, sarcomere length and soluble collagen. The findings from this experiment indicate that the known variants (soluble collagen, sarcomere length and desmin degradation) are related to shear force and compression in ovine biceps femoris.

  13. Effect of 8-week high-intensity stretching training on biceps femoris architecture.

    PubMed

    Freitas, Sandro R; Mil-Homens, Pedro

    2015-06-01

    Previous studies have reported no changes on muscle architecture (MA) after static stretching interventions; however, authors have argued that stretching duration and intensity may not have been sufficient. A high-intensity stretching intervention targeting the knee flexors with an 8-week duration was conducted to observe the effects on biceps femoris long head (BF) architecture. Participants (n = 5) performed an average of 3.1 assisted-stretching sessions per week, whereas a control group (n = 5) did not perform stretching. The knee extension passive maximal range of motion (ROM), and BF fascicle length (FL), fascicle angle, and muscle thickness were assessed before and after the intervention. A significant increase was observed for FL (+12.3 mm, p = 0.04) and maximal ROM (+14.2°, p = 0.04) for the stretching group after the intervention. No significant changes were observed for the control group in any parameter. An 8-week high-intensity stretching program was observed to efficiently increase the BF FL, as well as the knee extension maximal ROM. Stretching intensity and duration may play an important role on MA adaptation.

  14. EMG amplitude of the biceps femoris during jumping compared to landing movements.

    PubMed

    Padulo, Johnny; Tiloca, Alessandra; Powell, Douglas; Granatelli, Giampietro; Bianco, Antonino; Paoli, Antonio

    2013-01-01

    Hamstrings injury is a common occurrence in athletic performance. These injuries tend to occur during a deceleration or landing task suggesting the negative work may be a key component in hamstrings injury. The purpose of this study was to investigate the muscular activity (EMG) of the biceps femoris (BF) in different phases (concentric vs. eccentric) of a Counter Movement Jump (CMJ), Squat Jump (SJ) and the Braking Phase (BP) of a landing task. Twelve female volleyball players performed 5 CMJs, SJs and BPs while surface EMG was recorded using a MuscleLab (BoscoSystem(TM), Norway). EMG values were normalized to an maximal voluntary contraction. A repeated measures analysis of variance (ANOVA) was used to compare mean normalized EMG values of the concentric and eccentric portions of the CMJ with the BP and SJ. The ANOVA revealed significantly lower BF activation in the concentric and eccentric portions of the CMJ compared to the BP (64%, p < 0.001) and SJ (7%, p = 0.02), respectively. These findings suggest that the CMJ relies on a greater contribution of elastic tissues during the concentric and eccentric portions of the movement and thus requires less muscle activation of the BF.

  15. Ultrasound Assessment of the Rectus Femoris Cross-Sectional Area: Subject Position Implications.

    PubMed

    Hacker, Eileen Danaher; Peters, Tara; Garkova, Miglena

    2016-09-01

    Ultrasonic measurement of the rectus femoris (RF) is a novel, proxy measure for muscle strength. The impact of hip flexion/head of bed positioning on RF cross-sectional area (CSA) has not been fully explored. This study describes and compares differences in RF CSA across four degrees of hip flexion. This repeated-measures, comparative study enrolled healthy, pre-menopausal women (n = 20). RF CSA of the dominant leg was measured using the SonoSite M-Turbo ultrasound system with the head of bed at 0°, 20°, 30°, and 60°. One-way repeated measures indicated significant differences in RF CSA, F(3, 17) = 14.18, p < .001, with variation in hip flexion/head of bed elevation and significant RF CSA differences between: (a) 0° and 20°, (b) 0° and 30°, (c) 0° and 60°, and (d) 20° and 60°. Standardizing patient positioning when conducting ultrasonic measurement of RF CSA is vital for researchers who assess muscle mass.

  16. DOES RECTUS FEMORIS TRANSFER INCREASE KNEE FLEXION DURING STANCE PHASE IN CEREBRAL PALSY?

    PubMed Central

    de Morais, Mauro César; Blumetti, Francesco Camara; Kawamura, Cátia Miyuki; Lopes, José Augusto Fernandes; Neves, Daniella Lins; Cardoso, Michelle de Oliveira

    2016-01-01

    ABSTRACT Objective: To evaluate whether distal rectus femoris transfer (DRFT) is related to postoperative increase of knee flexion during the stance phase in cerebral palsy (CP). Methods: The inclusion criteria were Gross Motor Function Classification System (GMFCS) levels I-III, kinematic criteria for stiff-knee gait at baseline, and individuals who underwent orthopaedic surgery and had gait analyses performed before and after intervention. The patients included were divided into the following two groups: NO-DRFT (133 patients), which included patients who underwent orthopaedic surgery without DRFT, and DRFT (83 patients), which included patients who underwent orthopaedic surgery that included DRFT. The primary outcome was to evaluate in each group if minimum knee flexion in stance phase (FMJFA) changed after treatment. Results: The mean FMJFA increased from 13.19° to 16.74° (p=0.003) and from 10.60° to 14.80° (p=0.001) in Groups NO-DRFT and DRFT, respectively. The post-operative FMJFA was similar between groups NO-DRFT and DRFT (p=0.534). The increase of FMJFA during the second exam (from 13.01° to 22.51°) was higher among the GMFCS III patients in the DRFT group (p<0.001). Conclusion: In this study, DRFT did not generate additional increase of knee flexion during stance phase when compared to the control group. Level of Evidence III, Retrospective Comparative Study. PMID:26997910

  17. Age-related decrease of the phosphorus content in the ligamentum capitis femoris of monkeys.

    PubMed

    Tohno, Yoshiyuki; Tohno, Setsuko; Oishi, Takao; Minami, Takeshi; Khanpetch, Pongsak; Azuma, Cho; Quiggins, Ranida

    2014-10-01

    To elucidate compositional changes of the ligament with aging, the authors investigated age-related changes of elements in the ligamentum capitis femoris (LCF) of monkeys with a wide range of ages by direct chemical analysis. Used rhesus and Japanese monkeys consisted of 9 males and 22 females, ranging in age from newborn to 31 years (average age = 10.4 ± 10.9 years). After incineration with nitric acid and perchloric acid, element contents were determined by inductively coupled plasma-atomic emission spectrometry. It was found that the P content decreased significantly in the LCFs of monkeys with aging, but other six element contents, Ca, S, Mg, Zn, Fe, and Na, did not change significantly with aging. Assuming that the P content indicated the active cell density and the S content indicated the protein amount, an age-related change of the mass ratio of P/S was examined in the LCFs. The mass ratio of P/S decreased significantly in the LCFs in childhood. Regarding the relationships among elements, significant direct correlations were found among the Ca, P, S, and Mg contents in the LCFs. It was suggested that the active cell density of the connective tissue cells might decrease significantly in the LCF in childhood.

  18. Is myoelectric activity distributed equally within the rectus femoris muscle during loaded, squat exercises?

    PubMed

    de Souza, Leonardo Mendes Leal; da Fonseca, Desirée Barros; Cabral, Hélio da Veiga; de Oliveira, Liliam Fernandes; Vieira, Taian Martins

    2017-04-01

    Recent evidence suggests different regions of the rectus femoris (RF) muscle respond differently to squat exercises. Such differential adaptation may result from neural inputs distributed locally within RF, as previously reported for isometric contractions, walking and in response to fatigue. Here we therefore investigate whether myoelectric activity distributes evenly within RF during squat. Surface electromyograms (EMGs) were sampled proximally and distally from RF with arrays of electrodes, while thirteen healthy volunteers performed 10 consecutive squats with 20% and 40% of their body weight. The root mean square (RMS) value, computed separately for thirds of the concentric and eccentric phases, was considered to assess the proximo-distal changes in EMG amplitude during squat. The channels with variations in EMG amplitude during squat associated with shifts in the muscle innervation zone were excluded from analysis. No significant differences were observed between RF regions when considering squat phases and knee joint angles individually (P>0.16) while a significant interaction between phase and knee joint angle with detection site was observed (P<0.005). For the two loads considered, proximal RMS values were greater during the eccentric phase and for the more flexed knee joint position (P<0.001). Our results suggest inferences on the degree of RF activation during squat must be made cautiously from surface EMGs. Of more practical relevance, there may be a potential for the differential adaption of RF proximal and distal regions to squat exercises.

  19. The effectiveness of two novel techniques in establishing the mechanical and contractile responses of biceps femoris.

    PubMed

    Ditroilo, Massimiliano; Hunter, Angus M; Haslam, Samuel; De Vito, Giuseppe

    2011-08-01

    Portable tensiomyography (TMG) and myotonometry (MMT) devices have been developed to measure mechanical and contractile properties of skeletal muscle. The aim of this study was to explore the sensitivity of the aforementioned techniques in detecting a change in passive mechanical properties of the biceps femoris (BF) muscle as a result of change in knee joint angle (i.e. muscle length). BF responses were assessed in 16 young participants (23.4 ± 4.9 years), at three knee joint angles (0°, 45° and 90°), for maximal isometric torque (MIT) along with myo-electrical activity. Contractile and mechanical properties were measured in a relaxed state. Inter-day reliability of the TMG and MMT was also assessed. MIT changed significantly (p < 0.01) across the three angles, so did stiffness and other parameters measured with MMT (p < 0.01). Conversely, TMG could detect changes only at two knee angles (0° and 45°, p < 0.01), when there is enough tension in the muscle. Reliability was overall insufficient for TMG whilst absolute reliability was excellent (coefficient of variation < 5%) for MMT. The ability of MMT more than TMG to detect an inherent change in stiffness can be conceivably exploited in a number of clinical/therapeutic applications that have to do with unnatural changes in passive muscle stiffness.

  20. Biceps femoris and semitendinosus tendon/aponeurosis strain during passive and active (isometric) conditions.

    PubMed

    Kellis, Eleftherios

    2016-02-01

    The purpose of this study was to quantify strain and elongation of the long head of the biceps femoris (BFlh) and the semitendinosus (ST) tendon/aponeurosis. Forty participants performed passive knee extension trials from 90° of knee flexion to full extension (0°) followed by ramp isometric contractions of the knee flexors at 0°, 45° and 90° of knee flexion. Two ultrasound probes were used to visualize the displacement of BFlh and ST tendon/aponeurosis. Three-way analysis of variance designs indicated that: (a) Tendon/aponeurosis (passive) elongation and strain were higher for the BFlh than the ST as the knee was passively extended (p<0.05), (b) contraction at each angular position was accompanied by a smaller BFlh tendon/aponeurosis (active) strain and elongation than the ST at higher levels of effort (p<0.05) and (c) combined (passive and active) strain was significantly higher for the BFlh than ST during ramp contraction at 0° but the opposite was observed for the 45° and 90° flexion angle tests (p<0.05). Passive elongation of tendon/aponeurosis has an important effect on the tendon/aponeurosis behavior of the hamstrings and may contribute to a different loading of muscle fibers and tendinous tissue between BFlh and ST.

  1. Oxidative stress participates in quadriceps muscle dysfunction during the initiation of osteoarthritis in rats.

    PubMed

    Hsu, Dur-Zong; Chu, Pei-Yi; Wu, Po-Ting; Shen, Po-Chuan; Jou, I-Ming

    2015-01-01

    Osteoarthritis is the most common form of arthritis, affecting approximately 15% of the population. Quadriceps muscle weakness is one of the risk factors of osteoarthritis development. Oxidative stress has been reported to play an important role in the pathogenesis of various muscle dysfunction; however, whether it is involved in osteoarthritis-associated quadriceps muscle weakness has never been investigated. The aim of the present study is to examine the involvement of oxidative stress in quadriceps muscle dysfunction in the initiation of osteoarthritis in rats. Rat osteoarthritis was initiated by conducting meniscectomy (MNX). Quadriceps muscle dysfunction was evaluated by assessing muscular interleukin-6, citrate synthase activity, and myosin heavy chain IIa mRNA expression levels. Muscular oxidative stress was assessed by determining lipid peroxidation, Nrf2 expression, reactive oxygen species, and circulating antioxidants. Increased muscular interleukin-6 production as well as decreased citrate synthase activity and myosin heavy chain IIa mRNA expression were observed at 7 and 14 days after MNX. Biomarkers of oxidative stress were significantly increased after MNX. Muscular free radical counts were increased while glutathione and glutathione peroxidase expression were decreased in MNX-treated rats. We conclude that oxidative stress may be involved in the pathogenesis of muscle dysfunction in MNX-induced osteoarthritis.

  2. Relationship between knee alignment and the electromyographic activity of quadriceps muscles in patients with knee osteoarthritis

    PubMed Central

    Lim, Seong Hoon; Hong, Bo Young; Oh, Jee Hae; Lee, Jong In

    2015-01-01

    [Purpose] We evaluated the relationship between knee alignment and the electromyographic (EMG) activity of the vastus medialis (VM) to the vastus lateralis (VL) muscles in patients with knee osteoarthritis (OA) in a cross-sectional study. [Subjects and Methods] Forty subjects with knee OA were assessed by anatomic radiographic knee alignment and the VM/VL ratio was calculated. Surface EMG from both the VM and VL muscles were evaluated during maximal isometric contraction at 60° knee flexion. Simultaneously, peak quadriceps torque was assessed using an isokinetic dynamometer. Subjects were categorized into low, moderate, and high varus groups according to knee malalignment. The peak quadriceps torque and VM/VL ratio across groups, and their relationships with varus malalignment were analyzed. [Results] All subjects had medial compartment OA and the VM/VL ratio of all subjects was 1.31 ± 0.28 (mean ± SD). There were no significant differences in the peak quadriceps torque or VM/VL ratios across the groups nor were there any significant relationships with varus malalignment. [Conclusion] The VM/VL ratio and peak quadriceps torque were not associated with the severity of knee varus malalignment. PMID:25995602

  3. Fatigue effects on quadriceps and hamstrings activation in dancers performing drop landings.

    PubMed

    McEldowney, Kasey M; Hopper, Luke S; Etlin-Stein, Hannah; Redding, Emma

    2013-09-01

    Fatigue may reduce a dancer's ability to maintain the muscle synergies required for stable human movement. Therefore, fatigue presents as a potential risk factor for injury in dancers. Activation patterns of the quadriceps and hamstrings muscle groups in athletic populations have been consistently reported to alter in response to fatigue during landing tasks. It is unknown whether dancers demonstrate similar muscle activation patterns, nor if dancers respond to fatiguing protocols, with regard to muscle activation, in the same manner as their athletic counter-parts. The purpose of this study was to assess quadriceps and hamstrings activation levels in a cohort of dancers performing drop landings before and after completion of a dance-specific fatigue protocol, the High Intensity Dance Performance Fitness Test. Quadriceps and hamstrings co-contraction ratios significantly increased between pre- and post-fatigue conditions in a similar fashion to that reported in the literature. Therefore, the neuromuscular activation of the knee extensors and flexors in dancers changed in response to the dance-specific fatiguing protocol. Furthermore, quadriceps and hamstrings co-contraction ratios were substantially greater than previously reported in other athletic populations, due to low hamstrings activation levels. Future investigation of dancer biomechanical adaptations to fatigue would be beneficial to further examine the potential implications for injury risk.

  4. Identifying Dosage Effect of Light-Emitting Diode Therapy on Muscular Fatigue in Quadriceps.

    PubMed

    Hemmings, Thomas J; Kendall, Kristina L; Dobson, John L

    2017-02-01

    Hemmings, TJ, Kendall, KL, and Dobson, JL. Identifying dosage effect of light-emitting diode therapy on muscular fatigue in quadriceps. J Strength Cond Res 31(2): 395-402, 2017-The purpose of this study was to compare the effects of various dosages of light-emitting diode therapy (LEDT) on muscle fatigue while performing a single-leg extension to exhaustion. A total of 34 recreationally resistance-trained athletes between the ages of 18 and 26 participated in 4 trials. Each trial included pre-exercise/postexercise blood lactate measurements and 2 sets of 3 maximal voluntary isometric contractions (MVICs), followed by LEDT on 6 points across the superficial quadriceps. Each randomized trial consisted of a placebo, 30, 60, or 120 seconds on each point on the quadriceps. Three minutes after LEDT, the participants performed an eccentric leg extension with 120% of MVIC until fatigue. There was significant increase in the number of repetitions performed between the placebo treatment and 60 seconds (p = 0.023), as well as placebo and 120 seconds (p = 0.004) of irradiation on each point. There were no significant differences in blood lactate levels between any of the 4 trials. In conclusion, LEDT had a positive effect on performance when irradiating 6 points on the superficial quadriceps for 60 and 120 seconds before an eccentric leg extension.

  5. [Lewis-Sumner syndrome presenting unilateral quadriceps amyotrophy as an initial symptom].

    PubMed

    Fujiyama, J; Aita, T; Itoh, K; Hamano, T; Kumano, T; Kinomoto, K; Fujii, A; Yasokawa, T; Kuriyama, M

    2000-11-01

    We report a 55-year-old man with a chief complaint of wasting and weakness of the left quadriceps muscle. At age 54, he noticed difficulty in running and weakness in the left thigh, which gradually progressed. On the first admission to our hospital, based on the nerve conduction studies (NCS), the muscle biopsy findings showing neurologenic changes, and no abnormality of spinal MRI, we diagnosed as unilateral quadriceps amyotrophy, which resulted from an atypical form of spinal progressive muscular atrophy. One year later, he showed the bilateral hand weakness, conduction blocks on the right median and ulnar nerves by NCS, and the presence of serum anti-GM 1 antibody. From these findings, Lewis-Sumner syndrome was diagnosed. The therapy of high-dose intravenous immunoglobulin moderately improved his symptoms. The clinical symptoms of quadriceps amyotrophy is produced by various disorders including spinal progressive muscular atrophy, spinal extradural arachnoid cyst, rimmed vacuole myopathy, Becker dystrophy, limb-girdle dystrophy, and focal myositis. However, there have been no reports of a case of Lewis-Sumner syndrome. It is important to consider Lewis-Sumner syndrome in the differential diagnosis of quadriceps amyotrophy.

  6. Quadriceps Muscle Function After Rehabilitation With Cryotherapy in Patients With Anterior Cruciate Ligament Reconstruction

    PubMed Central

    Hart, Joseph M.; Kuenze, Christopher M.; Diduch, David R.; Ingersoll, Christopher D.

    2014-01-01

    Context: Persistent muscle weakness after anterior cruciate ligament (ACL) reconstruction may be due to underlying activation failure and arthrogenic muscle inhibition (AMI). Knee-joint cryotherapy has been shown to improve quadriceps function transiently in those with AMI, thereby providing an opportunity to improve quadriceps muscle activation and strength in patients with a reconstructed ACL. Objective: To compare quadriceps muscle function in patients with a reconstructed ACL who completed a 2-week intervention including daily cryotherapy (ice bag), daily exercises, or both. Design: Cross-sectional study. Setting: Laboratory. Patients or Other Participants: A total of 30 patients with reconstructed ACLs who were at least 6 months post-index surgery and had measurable quadriceps AMI. Intervention(s): The patients attended 4 supervised visits over a 2-week period. They were randomly assigned to receive 20 minutes of knee-joint cryotherapy, 1 hour of therapeutic rehabilitation exercises, or cryotherapy followed by exercises. Main Outcome Measure(s): We measured quadriceps Hoffmann reflex, normalized maximal voluntary isometric contraction torque, central activation ratio using the superimposed-burst technique, and patient-reported outcomes before and after the intervention period. Results: After the 2-week intervention period, patients who performed rehabilitation exercises immediately after cryotherapy had higher normalized maximal voluntary isometric contraction torques (P = .002, Cohen d effect size = 1.4) compared with those who received cryotherapy alone (P = .16, d = 0.58) or performed exercise alone (P = .16, d = 0.30). Conclusions: After ACL reconstruction, patients with AMI who performed rehabilitation exercises immediately after cryotherapy experienced greater strength gains than those who performed cryotherapy or exercises alone. PMID:25299442

  7. The effects of ACL injury on quadriceps and hamstring torque, work and power.

    PubMed

    Pincivero, Danny M; Heller, Brandan M; Hou, Su-I

    2002-09-01

    The aim of this study was to assess isokinetic torque, work and power between non-injured, ACL (anterior cruciate ligament)-deficient and ACL-reconstructed individuals. Ten healthy, non-injured individuals, seven unilateral ACL-deficient individuals and six unilateral ACL-reconstructed individuals were assessed for isokinetic quadriceps and hamstring strength at 1.05 and 3.14 rad.s-1. Peak torque, total work, average power and the ratio of peak torque to body mass were computed for both velocities. Peak torque was also corrected for body mass, using allometric modelling. The non-injured individuals showed significantly greater quadriceps peak torque to body mass ratios than the ACL-deficient and ACL-reconstructed individuals at both velocities, and greater hamstring peak torque to body mass ratios than the ACL-deficient group at 3.14 rad.s-1 (P < 0.05). The ACL-deficient individuals displayed greater quadriceps and hamstring peak torque, total work and average power than the non-injured individuals at 1.05 rad.s-1 (P < 0.05). The ACL-deficient individuals also displayed significantly greater peak torque, total work and average power than the ACL-reconstructed individuals for the quadriceps at both velocities (P < 0.05). The ACL-deficient individuals demonstrated greater hamstring peak torque and total work than the non-injured individuals at both velocities (P < 0.05). The allometrically modelled peak torques at both isokinetic velocities demonstrated that the quadriceps muscle values were significantly higher in the non-involved than the involved limb. The hamstring peak torques corrected for body mass were significantly higher in the non-involved than the involved limb only at 1.05 rad.s-1. The main finding from the present study is that isokinetic measures in ratio-scaled or absolute units yield a different outcome and, hence, interpretation compared with the allometric approach.

  8. Anatomy of the long head of biceps femoris: An ultrasound study.

    PubMed

    Tosovic, D; Muirhead, J C; Brown, J M M; Woodley, S J

    2016-09-01

    Hamstring strains, particularly involving the long head of biceps femoris (BFlh) at the proximal musculotendinous junction (MTJ), are commonly experienced by athletes. With the use of diagnostic ultrasound increasing, an in-depth knowledge of normal ultrasonographic anatomy is fundamental to better understanding hamstring strain. The aim of this study was to describe the architecture of BFlh, using ultrasonography, in young men and cadaver specimens. BFlh morphology was examined in 19 healthy male participants (mean age 21.6 years) using ultrasound. Muscle, tendon and MTJ lengths were recorded and architectural parameters assessed at four standardised points along the muscle. Measurement accuracy was validated by ultrasound and dissection of BFlh in six male cadaver lower limbs (mean age 76 years). Intra-rater reliability of architectural parameters was examined for repeat scans, image analysis and dissection measurements. Distally the BFlh muscle had significantly (P < 0.05) shorter fascicles and larger pennation angles than proximal sites. Agreement between ultrasound and dissection (cadaver study) was excellent for all architectural parameters, except pennation angle (PA), and MTJ length. All other measures demonstrated good-excellent repeatability. BFlh is not uniform in architecture when imaged using ultrasound. It is likely that its distal-most segment is better suited for force production in comparison to the more proximal segments, which show excursive potential, traits which possibly contribute to the high rate of injury at the proximal MTJ. The data presented in this study provide specific knowledge of the normal ultrasonographic anatomy of BFlh, which should be of assistance in analysing BFlh injury via imaging. Clin. Anat. 29:738-745, 2016. © 2016 Wiley Periodicals, Inc.

  9. Accuracy assessment of CKC high-density surface EMG decomposition in biceps femoris muscle

    NASA Astrophysics Data System (ADS)

    Marateb, H. R.; McGill, K. C.; Holobar, A.; Lateva, Z. C.; Mansourian, M.; Merletti, R.

    2011-10-01

    The aim of this study was to assess the accuracy of the convolution kernel compensation (CKC) method in decomposing high-density surface EMG (HDsEMG) signals from the pennate biceps femoris long-head muscle. Although the CKC method has already been thoroughly assessed in parallel-fibered muscles, there are several factors that could hinder its performance in pennate muscles. Namely, HDsEMG signals from pennate and parallel-fibered muscles differ considerably in terms of the number of detectable motor units (MUs) and the spatial distribution of the motor-unit action potentials (MUAPs). In this study, monopolar surface EMG signals were recorded from five normal subjects during low-force voluntary isometric contractions using a 92-channel electrode grid with 8 mm inter-electrode distances. Intramuscular EMG (iEMG) signals were recorded concurrently using monopolar needles. The HDsEMG and iEMG signals were independently decomposed into MUAP trains, and the iEMG results were verified using a rigorous a posteriori statistical analysis. HDsEMG decomposition identified from 2 to 30 MUAP trains per contraction. 3 ± 2 of these trains were also reliably detected by iEMG decomposition. The measured CKC decomposition accuracy of these common trains over a selected 10 s interval was 91.5 ± 5.8%. The other trains were not assessed. The significant factors that affected CKC decomposition accuracy were the number of HDsEMG channels that were free of technical artifact and the distinguishability of the MUAPs in the HDsEMG signal (P < 0.05). These results show that the CKC method reliably identifies at least a subset of MUAP trains in HDsEMG signals from low force contractions in pennate muscles.

  10. Measurement of rectus femoris muscle velocities during patellar tendon jerk using vector tissue doppler imaging.

    PubMed

    Sikdar, Siddhartha; Lebiedowska, Maria; Eranki, Avinash; Garmirian, Lindsay; Damiano, Diane

    2009-01-01

    We have developed a vector tissue Doppler imaging (TDI) system based on a clinical scanner that can be used to measure muscle velocities independent of the direction of motion. This method overcomes the limitations of conventional Doppler ultrasound, which can only measure velocity components along the ultrasound beam. In this study, we utilized this method to investigate the rectus femoris muscle velocities during a patellar tendon jerk test. Our goal was to investigate whether the muscle elongation velocities during a brisk tendon tap fall within the normal range of velocities that are expected due to rapid stretch of limb segments. In a preliminary study, we recruited six healthy volunteers (three men and three women) following informed consent. The stretch reflex response to tendon tap was evaluated by measuring: (1) the tapping force using an accelerometer instrumented to the neurological hammer (2) the angular velocities of the knee extension and flexion using a electrogoniometer (3) reflex activation using electromyography (EMG) and (4) muscle elongation, extension and flexion velocities using vector TDI. The passive joint angular velocity was linearly related to the passive muscle elongation velocity (R(2)=0.88). The maximum estimated joint angular velocity corresponding to muscle elongation due to tendon tap was less than 8.25 radians/s. This preliminary study demonstrates the feasibility of vector TDI for measuring longitudinal muscle velocities and indicates that the muscle elongation velocities during a clinical tendon tap test are within the normal range of values for rapid limb stretch encountered in daily life. With further refinement, vector TDI could become a powerful method for quantitative evaluation of muscle motion in musculoskeletal disorders.

  11. Short-latency crossed responses in the human biceps femoris muscle

    PubMed Central

    Stevenson, Andrew J T; Kamavuako, Ernest N; Geertsen, Svend S; Farina, Dario; Mrachacz-Kersting, Natalie

    2015-01-01

    Interlimb reflexes contribute to the central neural co-ordination between different limbs in both humans and animals. Although commissural interneurons have only been directly identified in animals, spinally-mediated interlimb reflexes have been discovered in a number of human lower limb muscles, indicating their existence in humans. The present study aimed to investigate whether short-latency crossed-spinal reflexes are present in the contralateral biceps femoris (cBF) muscle following ipsilateral knee (iKnee) joint rotations during a sitting task, where participants maintained a slight pre-contraction in the cBF. Following iKnee extension joint rotations, an inhibitory reflex was observed in the surface electromyographic (EMG) activity of the cBF, whereas a facilitatory reflex was observed in the cBF following iKnee flexion joint rotations. The onset latency of both cBF reflexes was 44 ms, which is too fast for a transcortical pathway to contribute. The cBF inhibitory and facilitatory reflexes followed the automatic gain control principle, with the size of the response increasing as the level of background pre-contraction in the cBF muscle increased. In addition to the surface EMG, both short-latency inhibitory and facilitatory cBF reflexes were recorded directly at the motor unit level by i.m. EMG, and the same population of cBF motor units that were inhibited following iKnee extension joint rotations were facilitated following iKnee flexion joint rotations. Therefore, parallel interneuronal pathways (probably involving commissural interneurons) from ipsilateral afferents to common motoneurons in the contralateral leg can probably explain the perturbation direction-dependent reversal in the sign of the short-latency cBF reflex. PMID:25970767

  12. The use of dielectric properties and other physical analyses for assessing protein denaturation in beef biceps femoris muscle during cooking from 5 to 85°C.

    PubMed

    Brunton, N P; Lyng, J G; Zhang, L; Jacquier, J C

    2006-02-01

    Dielectric properties of beef biceps femoris muscle were recorded during heating (5-85°C) to assess their linkage to phase changes monitored by differential scanning calorimetry (DSC) and rheology. DSC indicated endotherms between 56 and 81°C corresponding to denaturation of actin, collagen and myosin. Matching changes in dielectric properties (dielectric constant (ε') and loss factor (ε″)) were noted at radio and/or microwave frequencies though the nature of the change differed depending upon frequency. The main observation in ε' was an increase above 65-66°C, most likely due to fluid release on collagen denaturation. This fluid plus liquid from myosin denaturation most likely solvated ions freed during myosin denaturation which manifested as an ε″ increase. However, it must be noted that meat structural protein denaturation is compounded with physical shrinkage which can also influence dielectric properties. Rheological parameters of beef muscle heated from 5 to 85°C also displayed marked changes relating to structural protein denaturation.

  13. Effect of time-dependent cryotherapy on redox balance of quadriceps injuries.

    PubMed

    Silva, Marco Aurélio dos Santos; Carvalho, Taiara Ramos de; Cruz, Amanda Cristina Marques Barros da; Jesus, Lennon Rafael Guedine de; Silva Neto, Larissa Alexsandra da; Trajano, Eduardo Tavares Lima; Bezerra, Frank Silva

    2016-02-01

    Muscle trauma represents a high number of injuries in professional sport and recreation and may occur through several mechanisms. This study aims at analyzing time-dependent effects of cryotherapy on the redox balance in lesioned quadriceps muscles in F1 mice. Twenty male F1 mice were divided into five groups: (a) animals were not subjected to muscle lesioning or treatment (CTR); (b) quadriceps muscle was lesioned without treatment (L); (c) quadriceps muscle was lesioned and treated with cryotherapy for 5 min (LC5); (d) quadriceps muscle was lesioned and treated with cryotherapy for 20 min (LC20); and quadriceps muscle was lesioned and treated with cryotherapy for 40 min (LC40). The mice were euthanized; the quadriceps muscles were collected and subjected to analyses for levels of protein, hydroperoxides, nitrite, catalase (CAT) activity, oxidized glutathione (GSSG) and reduced glutathione (GSH). Protein levels were reduced in L (-39%; p < 0.05), LC5 (-54%; p < 0.05), LC20 (-40%; p < 0.05) and LC40 (-50%; p < 0.05) compared to CTR. There was an increase in lipid peroxidation in L (158%; p < 0.05), LC5 (300%; p < 0.01), LC20 (292%; p < 0.01) and LC40 (362%; p < 0.01) compared to CTR. We observed a significant increase in CAT activity in L (164%; p < 0.05) and LC5 (193%; p < 0.01) compared to CTR; a significant reduction in GSH in L (-60%; p < 0.05) and LC20 (-61%; p < 0.05) compared to CTR; and a significant increase in GSSG in LC5 (171%; p < 0.05) compared to CTR. In addition, GSH/GSSG was reduced in L (-89%; p < 0.01), LC5 (-95%; p < 0.01), LC20 (-59%; p < 0.05), and LC40 (-82%; p < 0.01) compared to CTR. This study showed that the cryotherapy does not improve the oxidative stress in lesioned muscles.

  14. Evidence for interneuronally mediated Ia excitatory effects to human quadriceps motoneurones.

    PubMed Central

    Fournier, E; Meunier, S; Pierrot-Deseilligny, E; Shindo, M

    1986-01-01

    The possibility was investigated that interneuronal pathways contribute to Ia excitation of quadriceps motoneurones in normal man. Two techniques were used: the indirect spatial facilitation technique for investigating summation of Ia excitatory effects in interneurones which may be interposed in pathways to quadriceps motoneurones; the post-stimulus time histogram method for time course measurement of the firing probability of voluntarily activated motor units following femoral nerve stimulation. The spatial facilitation technique was applied while using the quadriceps H reflex to assess the excitability of the whole motoneurone pool: the comparison was made between the excitatory effects of two conditioning stimuli applied either separately or together. Summation of effects at a premotoneuronal level is suggested if facilitation of the reflex evoked on combined conditioning stimulation is larger than the algebraic sum of facilitations evoked by separate stimuli. Quadriceps tendon tap and electrical stimulations applied to either the femoral nerve or to two of its branches, the nerves to the vastus lateralis and vastus medialis muscles, were used as conditioning stimuli. Since these stimuli were very weak (their strength being about at the threshold for facilitation of the test reflex), it can be assumed that they activated predominantly Ia fibres. The facilitation of the quadriceps H reflex evoked on combined stimulation was significantly larger than the algebraic sum of facilitations evoked by separate stimuli. In many experiments, although conditioning stimuli did not evoke any reflex facilitation when applied alone, a significant facilitation appeared on combined stimulation. This 'extra' facilitation of the reflex on combined stimulation appeared with a central latency of 4-5 ms. It is argued that the only mechanism compatible with such a latency is summation at a premotoneuronal level. Post-stimulus time histograms (p.s.t.h.s) of voluntarily activated

  15. Quadriceps and Hamstrings Morphology Is Related to Walking Mechanics and Knee Cartilage MRI Relaxation Times in Young Adults

    PubMed Central

    KUMAR, DEEPAK; SUBBURAJ, KARUPPPASAMY; LIN, WILSON; KARAMPINOS, DIMITRIOS C.; MCCULLOCH, CHARLES E.; LI, XIAOJUAN; LINK, THOMAS M.; SOUZA, RICHARD B.; MAJUMDAR, SHARMILA

    2015-01-01

    STUDY DESIGN Controlled laboratory study using a cross-sectional design. OBJECTIVES To analyze the relationship of quadriceps-hamstrings and medial-lateral quadriceps anatomical cross-sectional area (ACSA) ratios with knee loads during walking and articular and meniscal cartilage composition in young, healthy subjects. BACKGROUND Muscle forces affect knee loading during walking, but it is not known if muscle morphology is associated with walking mechanics and cartilage composition in young subjects. METHODS Forty-two knees from 27 young, healthy, active volunteers (age, 20-35 years; body mass index, <28 kg/m2) underwent 3-T magnetic resonance imaging (MRI) and 3-D motion capture. Standard MRI sequences were used for articular and meniscal cartilage T1rho and T2 relaxation times and for quadriceps and hamstrings muscle ACSA. Frontal plane kinetics during the stance phase of walking was calculated. Generalized estimating equation models were used to identify muscle variables that predicted MRI and gait parameters. RESULTS Quadriceps-hamstrings and medial-lateral quadriceps ACSA ratios were positively related to frontal plane loading (β = .27-.54, P≤.006), global articular cartilage relaxation times (β = .22-.28, P≤.041), and the medial-lateral ratio of meniscus T1rho relaxation time (β = .26-.36, P≤.049). The medial-lateral quadriceps ACSA ratio was positively related to global meniscus T1rho relaxation times (β = .30, P = .046). CONCLUSION Higher quadriceps-hamstrings and medial-lateral quadriceps ACSA ratios were associated with higher frontal plane loading during walking and with articular and meniscal cartilage T1rho and T2 relaxation times. These findings highlight the relationships between different knee tissues and knee mechanics in young, healthy individuals. PMID:24175607

  16. Surgical management of acute quadriceps tendon rupture (a case report with literature review)

    PubMed Central

    Ennaciri, Badr; Montbarbon, Eric; Beaudouin, Emmanuel

    2015-01-01

    Quadriceps tendon rupture is uncommon and often overlooked in emergency. Tearing affects weakening tendon by systemic diseases or some medications. The mechanism is generally indirect. Inability to actively extend the knee associated to a supra-patellar defect evoke easily the diagnosis without other investigations. Surgical repair is realized in emergency to completely restore the extension. We report a case of a patient who has sustained of complete quadriceps tendon tear after a long period of tendon weakening by statin therapy, hypertension and diabetes. The repair has consisted on end-to-end Krackow sutures associated with bone suture to the proximal pole of the patella. Surgeons and emergency physicians must think to this form of extensor apparatus rupture, because early diagnosis leads to early treatment and to best outcomes. PMID:26958106

  17. Acute effects of static stretching on peak torque and the hamstrings-to-quadriceps conventional and functional ratios.

    PubMed

    Costa, P B; Ryan, E D; Herda, T J; Walter, A A; Defreitas, J M; Stout, J R; Cramer, J T

    2013-02-01

    Recent evidence has shown acute static stretching may decrease hamstring-to-quadriceps (H:Q) ratios. However, the effects of static stretching on the functional H:Q ratio, which uses eccentric hamstrings muscle actions, have not been investigated. This study examined the acute effects of hamstrings and quadriceps static stretching on leg extensor and flexor concentric peak torque (PT), leg flexor eccentric PT, and the conventional and functional H:Q ratios. Twenty-two women (mean ± SD age=20.6 ± 1.9 years; body mass=64.6 ± 9.1 kg; height=164.5 ± 6.4 cm) performed three maximal voluntary unilateral isokinetic leg extension, flexion, and eccentric hamstring muscle actions at the angular velocities of 60 and 180°/s before and after a bout of hamstrings, quadriceps, and combined hamstrings and quadriceps static stretching, and a control condition. Two-way repeated measures ANOVAs (time × condition) were used to analyze the leg extension, flexion, and eccentric PT as well as the conventional and functional H:Q ratios. Results indicated that when collapsed across velocity, hamstrings-only stretching decreased the conventional ratios (P<0.05). Quadriceps-only and hamstrings and quadriceps stretching decreased the functional ratios (P<0.05). These findings suggested that stretching may adversely affect the conventional and functional H:Q ratios.

  18. Fatigue affects peak joint torque angle in hamstrings but not in quadriceps.

    PubMed

    Coratella, Giuseppe; Bellin, Giuseppe; Beato, Marco; Schena, Federico

    2015-01-01

    Primary aim of this study was to investigate peak joint torque angle (i.e. the angle of peak torque) changes recorded during an isokinetic test before and after a fatiguing soccer match simulation. Secondarily we want to investigate functional Hecc:Qconc and conventional Hconc:Qconc ratio changes due to fatigue. Before and after a standardised soccer match simulation, twenty-two healthy male amateur soccer players performed maximal isokinetic strength tests both for hamstrings and for quadriceps muscles at 1.05 rad · s(‒1), 3.14 rad · s(‒1) and 5.24 rad · s(‒1). Peak joint torque angle, peak torque and both functional Hecc:Qconc and conventional Hconc:Qconc ratios were examined. Both dominant and non-dominant limbs were tested. Peak joint torque angle significantly increased only in knee flexors. Both eccentric and concentric contractions resulted in such increment, which occurred in both limbs. No changes were found in quadriceps peak joint torque angle. Participants experienced a significant decrease in torque both in hamstrings and in quadriceps. Functional Hecc:Qconc ratio was lower only in dominant limb at higher velocities, while Hconc:Qconc did not change. This study showed after specific fatiguing task changes in hamstrings only torque/angle relationship. Hamstrings injury risk could depend on altered torque when knee is close to extension, coupled with a greater peak torque decrement compared to quadriceps. These results suggest the use eccentric based training to prevent hamstrings shift towards shorter length.

  19. Quadriceps Rate of Force Development affects Gait and Function in People with Knee Osteoarthritis

    PubMed Central

    Winters, Joshua D.; Rudolph, Katherine S.

    2014-01-01

    Objective Quadriceps weakness exists in people with knee osteoarthritis (OA) but other muscle factors like rate of force development (RFD) may also be affected by knee OA. The purpose of this study was to determine if people with knee OA have deficits in quadriceps RFD, determine if quadriceps RFD would improve predicting knee joint power absorption and generation during free and fast walking, and determine if RFD would improve predicting functional outcomes. Methods 26 subjects with knee OA and 23 healthy control subjects performed maximal voluntary isometric strength (MVIC) and RFD measures of the quadriceps. Subjects also underwent a 3-D motion analysis of both self-selected free and self-selected fast walking speeds. Joint kinetics were calculated from inverse dynamics. Results RFD was not different by group (p=0.763), however the OA subjects generated the highest peak RFD at a lower %MVIC (p=0.008). Controls walked significantly faster at both free and fast walking speeds (p=0.001, p=0.029). Knee angles at heel strike and peak knee extension were lower (p=0.004, p=0.027) in the OA group. During fast walking knee power generation was higher in Controls (p=0.028). MVIC and force of highest peak RFD predicted KOOS ADL score in the OA subjects, but only MVIC predicted stair climbing time. Conclusions The submaximal force at which peak RFD occurs plays a significant role in knee joint power as well as functional measures in the OA subjects, providing further evidence that factors other than maximal strength are also important in people with knee OA. PMID:24240535

  20. [Missed diagnosis in delayed recognition of bilateral simultaneous rupture of the quadriceps tendons].

    PubMed

    Wick, M; Müller, E J; Ekkernkamp, A; Muhr, G

    1997-04-01

    In this article we report a very rare case of simultaneous and bilateral rupture of the quadriceps tendon in a 38-year-old patient. The initial diagnosis was "herniated vertebral disk". Although there was an extensive neurological and psychiatric examination in combination with several operations, it took almost 3 months until the real reason was found. In this case report we describe our postoperative treatment of early mobilization and compare it with other therapies.

  1. Dynamic in vivo 3-dimensional moment arms of the individual quadriceps components.

    PubMed

    Wilson, Nicole A; Sheehan, Frances T

    2009-08-25

    The purpose of this study was to provide the first in vivo 3-dimensional (3D) measures of knee extensor moment arms, measured during dynamic volitional activity. The hypothesis was that the vastus lateralis (VL) and vastus medialis (VM) have significant off-axis moment arms compared to the central quadriceps components. After obtaining informed consent, three 3D dynamic cine phase contrast (PC) MRI sets (x,y,z velocity and anatomic images) were acquired from 22 subjects during active knee flexion and extension. Using a sagittal-oblique and two coronal-oblique imaging planes, the origins and insertions of each quadriceps muscle were identified and tracked through each time frame by integrating the cine-PC velocity data. The moment arm (MA) and relative moment (RM, defined as the cross product of the tendon line-of-action and a line connecting the line-of-action with the patellar center of mass) were calculated for each quadriceps component. The tendencies of the VM and VL to produce patellar tilt were evenly balanced. Interestingly, the magnitude of RM-P(Spin) for the VM and VL is approximately four times greater than the magnitude of RM-P(Tilt) for the same muscles suggesting that patellar spin may play a more important role in patellofemoral kinematics than previously thought. Thus, a force imbalance that leads to excessive lateral tilt, such as VM weakness in patellofemoral pain syndrome, would produce excessive negative spin (positive spin: superior patellar pole rotates laterally) and to a much greater degree. This would explain the increased negative spin found in recent studies of patellar maltracking. Assessing the contribution of each quadriceps component in three dimensions provides a more complete understanding of muscle functionality.

  2. Inflammatory cytokine expression in the quadriceps of rats with posttraumatic knee stiffness: A preliminary study.

    PubMed

    Liu, Kemin; Wang, Fei; Cui, Zhigang; Liu, Sihai; Han, Xinzuo

    2015-06-01

    The primary purpose of this study was to investigate cytokine expression in the quadriceps of rats with posttraumatic knee stiffness (PTKS) and to determine the effect of exercise training on these cytokines at different follow-up time points. The PTKS rats were randomly assigned into two even groups. The treatment group received exercise training, while the control group received no treatment. Quadriceps specimens were harvested randomly from each group at 8, 12, 16, and 20 weeks. RT-qPCR and immunohistochemical analyses were used to assess the protein and mRNA expression levels of the cytokines IL-1, IL-2, TNF-α, COX-1, and COX-2. TNF-α immunostaining did not differ between the treated and control group tissues, whereas weak immunostaining was observed for all other cytokines in the specimens from the treatment group compared with those from the control group at approximately 12 and 20 weeks. The cytokine levels decreased at approximately 8 weeks in the treatment group, whereas these levels remained elevated or plateaued in the control group. These differences were statistically significant (p<0.05). This study demonstrated that the expression of cytokines IL-1, IL-2, COX-1, and COX-2 increased in the quadriceps of rats with PTKS and that exercise training affected the observed profile trends of these cytokines.

  3. Ultrasound characteristics of the patellar and quadriceps tendons among young elite athletes.

    PubMed

    Visnes, H; Tegnander, A; Bahr, R

    2015-04-01

    Tendons adapt in response to sports-specific loading, but sometimes develop tendinopathy. If the presence of ultrasound changes like hypoechoic areas and neovascularization in asymptomatic tendons precede (and predict) future tendon problems is unknown. The aim of this prospective cohort study was to investigate the relationship between the development of ultrasound changes in the patellar and quadriceps tendons and symptoms of jumper's knee, as well to examine the medium-term effects of intensive training on tendon thickness among adolescent athletes. Elite junior volleyball athletes were followed with semi-annual ultrasound and clinical examinations (average follow-up: 1.7 years). Of the 141 asymptomatic athletes included, 22 athletes (35 patellar tendons) developed jumper's knee. In a multivariate logistic regression analysis, a baseline finding of a hypoechoic tendon area (odds ratio 3.3, 95% confidence interval 1.1 to 9.2) increased the risk of developing symptoms of jumper's knee. Patellar tendon thickness among healthy athletes did not change (Wilk's lambda, P = 0.07) while quadriceps tendon thickness increased (P = 0.001). In conclusion, ultrasound changes at baseline were risk factors for developing symptoms of jumper's knee. Also, among healthy athletes, we observed a 7-11% increase in quadriceps tendon thickness, while there was no increase in patellar tendon thickness.

  4. Surgical Treatment of Neglected Traumatic Quadriceps Tendon Rupture with Knee Ankylosis

    PubMed Central

    Lee, Seung-Hun; Seon, Jong-Keun; Woo, Seong-Hwan

    2016-01-01

    Quadriceps tendon rupture is an uncommon injury. This disabling condition is the result of direct or indirect trauma. It requires surgical repair to avoid poor outcomes in cases of neglected or chronic rupture. In most acute cases, simple tendon suture or reinsertion is suitable for an extensor mechanism reconstruction of the knee joint. However, chronic lesions often require a tendon graft or flap reconstruction. We report a case of a 15-year-old male who was diagnosed with a chronic quadriceps rupture with a patellar superior pole fracture. We performed quadriceps reconstruction using tibialis anterior allograft tendon and additional screw fixation to reconstruct the extensor mechanism and recover knee joint range of motion to prevent a high-level functional restriction. The treatment was difficult and limited due to neglect for 9-months that led to ankylosis accompanied with nonunion of tibial fracture. Our surgical treatment using allograft tendon resulted in a very good outcome after 30 months of follow-up. PMID:27274474

  5. A 6-week Sprint Interval Training Program Changes Anaerobic Power, Quadriceps Moment, and Subcutaneous Tissue Thickness.

    PubMed

    Han, Seunguk; Lee, Hyungkyu; Kim, Hyungkee; Kim, Dasol; Choi, Changkyu; Park, Jihong

    2017-02-01

    We examined the effects of a 6-week 40-m one-way sprint interval training program (based on sprint time). 13 untrained healthy male collegiate students performed six 40-m sprints with a 60-s resting interval between sprints during the first week, and one sprint was added each week until the sixth week. If the 40-m sprint time exceeded 110% of the fastest baseline 40-m sprint time, the run was repeated. Repeated-sprint cycling test (every 3 weeks), quadriceps moment (every 2 weeks), and abdominal and thigh subcutaneous tissue thickness (every 2 weeks) were measured. Compared to baseline, mean power output improved at week 3 (16.27 vs. 17.73 Watt/kg, p=0.004). Regardless of side, quadriceps moment began to increase at week 4 (2.88 vs. 3.15 N·m/kg, p=0.03). Subcutaneous tissue thickness was reduced at week 2 (abdominal: 11.19 vs. 9.65 mm, p=0.01; thigh: 9.17 vs. 8.12 mm, p=0.009). Our results suggest that (1) sprint training with an intensity of 110% of the fastest baseline 40-m sprint time with the addition of one sprint per week produces similar effects to other training programs, and (2) untrained individuals need 4 weeks of training for strength development in the quadriceps and 2 weeks for reduction in fat tissue thickness.

  6. The effect of quadriceps muscle fatigue on position matching at the knee.

    PubMed

    Givoni, Nathan J; Pham, Tuan; Allen, Trevor J; Proske, Uwe

    2007-10-01

    This is a report of the effects of exercise on position matching at the knee. Young adult subjects were required to step down a set of stairs (792 steps), representing eccentric-biased exercise of the quadriceps muscle, or step up them, concentric-biased exercise. Immediately after eccentric exercise subjects showed a mean force drop of 28% (+/- 6%, s.e.m.) of the control value in their exercised quadriceps muscle, which was accompanied by 4.8 deg (+/- 0.8 deg) of error between reference and matching legs in a position matching task at the knee. Similarly concentric exercise was followed by a force drop of 15% (+/- 3%) and matching errors of 3.7 deg (+/- 0.4 deg). These effects were significant. The direction of the errors suggested that subjects perceived their exercised muscles to be longer that they actually were. This finding was not consistent with the hypothesis that the increase in effort required to support the leg after fatigue from exercise was responsible for the errors. It is hypothesized that position sense in an unsupported leg arises, in part, from operation of an internal forward model. When the motor command is increased to compensate for the effects of fatigue, the comparison between predicted and actual feedback from quadriceps leads to the impression that the muscle is longer than it actually is. The exercise effects on proprioception may have implications for sports injuries and for evaluation of the factors leading to falls in the elderly.

  7. Asymptomatic Achilles, patellar, and quadriceps tendinopathy: a longitudinal clinical and ultrasonographic study in elite fencers.

    PubMed

    Giombini, A; Dragoni, S; Di Cesare, A; Di Cesare, M; Del Buono, A; Maffulli, N

    2013-06-01

    Lower limb tendon changes detected at imaging are common among asymptomatic athletes. We aimed to prospectively assess the clinical status, tendon structure, and vascularity of lower limb tendons of elite fencers, and predict the risk of developing symptoms over time. Clinical examination, changes at ultrasonography (US), and Power Doppler (PD) flow of both the Achilles, patellar, and quadriceps tendon were assessed in 37 elite fencers in January 2007 and 3 years after. Two hundred and twenty-two tendons were examined. At the last appointment, patellar tendons diagnosed as abnormal at baseline were more likely to develop symptoms than those normal at baseline (P < 0.05, Fisher's exact test), while US and PD abnormalities on Achilles and quadriceps tendons were no predictive for development of symptoms over years. A very low percentage of tendons diagnosed as normal at baseline (1.45%) showed US abnormalities at 3-year follow-up. In asymptomatic elite fencers, structural changes are relatively common at US and PD assessment of Achilles, quadriceps, and patellar tendons. It seems unlikely that additional PD investigations provide further information or change prognosis in patients with US diagnosis of tendinopathy.

  8. Clinical utility of the Duncan-Ely test for rectus femoris dysfunction during the swing phase of gait.

    PubMed

    Marks, M C; Alexander, J; Sutherland, D H; Chambers, H G

    2003-11-01

    The Ely Test (or Duncan-Ely test) has been accepted as a clinical tool to assess rectus femoris spasticity by passively flexing the knee rapidly while the patient lies prone in a relaxed state. In this retrospective review, patients' dynamic knee range of motion (ROM) during gait and an electromyogram (EMG) were compared with the results of the Ely test. Data for 70 patients (44 males, 26 females; 104 limbs) were included. Mean age of patients was 13 years, SD 9 years, range 4 years 5 months to 54 years. All patients were diagnosed with cerebral palsy (spastic diplegia, n = 42; spastic quadriplegia, n = 15, and hemiplegia, n = 13). All patients were ambulatory (50 independent, 20 with assistive devices). A standard matrix was used to calculate sensitivity and specificity of the Ely test as well as its positive and negative predictive value. For the gait variables examined (decreased dynamic knee ROM, timing of peak knee flexion, and abnormal EMG in swing) the sensitivity of the Ely test ranged from 56 to 59% and the specificity ranged from 64 to 85%. For the same variables the positive predictive value ranged from 91 to 98% and the negative predictive value ranged from 4 to 19%. The Ely test was shown to have a good positive predictive value (i.e. the certainty about the presence of rectus spasticity in patients with a positive Ely test result) for rectus femoris dysfunction during gait.

  9. Quality properties and adsorption behavior of freeze-dried beef meat from the Biceps femoris and Semimembranosus muscles.

    PubMed

    Aykın, Elif; Erbaş, Mustafa

    2016-11-01

    The aim of this research was to determine the quality properties and adsorption behavior of freeze-dried beef meat from the Biceps femoris and Semimembranosus muscles. Most quality properties of both muscles were similar apart from total fat content. Freeze-dried meat pieces were kept in ten different equilibrium levels of relative humidity (2.0-97.3%) at 5, 15, 25 and 30°C. The experimental data were evaluated using BET (Brunauer-Emmett-Teller) and GAB (Guggenheim, Anderson and deBoer) models. The equilibrium moisture contents of freeze-dried Biceps femoris were lower than those of Semimembranosus at all water activities and temperature. The constants m0 and C of BET and GAB equations were determined to be between 6.27 and 8.07g/100g dry matter and 9.32-13.73, respectively. Constant k was about 0.90 at all temperatures, and the GAB equation exhibited a better fit to the experimental data of both muscles as a result of all %E values being approximately equal to 10%.

  10. Real-time measurement of rectus femoris muscle kinematics during drop jump using ultrasound imaging: a preliminary study.

    PubMed

    Eranki, Avinash; Cortes, Nelson; Ferencek Gregurić, Zrinka; Kim, John J; Sikdar, Siddhartha

    2012-01-01

    We have developed an office based vector tissue Doppler imaging (vTDI) that can be used to quantitatively measure muscle kinematics using ultrasound. The goal of this preliminary study was to investigate if vTDI measures are repeatable and can be used robustly to measure and understand the kinematics of the rectus femoris muscle during a drop jump task. Data were collected from 8 healthy volunteers. Vector TDI along with a high speed camera video was used to better understand the dynamics of the drop jump. Our results indicate that the peak resultant vector velocity of the rectus femoris immediately following landing was repeatable across trials (intraclass correlation coefficient=0.9).The peak velocity had a relatively narrow range in 6 out of 8 subjects (48-62 cm/s), while in the remaining two subjects it exceeded 70 cm/s. The entire drop jump lasted for 1.45 0.27 seconds. The waveform of muscle velocity could be used to identify different phases of the jump. Also, the movement of the ultrasound transducer holder was minimal with peak deflection of 0.91 0.54 degrees over all trials. Vector TDI can be implemented in a clinical setting using an ultrasound system with a research interface to better understand the muscle kinematics in patients with ACL injuries.

  11. Iatrogenic Pseudo-aneurysm of Profunda Femoris Artery Following Fixation of Intertrochanteric Femur Fracture – A Case Report and Review of Literature

    PubMed Central

    Aggarwal, Rishi Anil; Purohit, Shaligram; Bandagi, Gokul; Marathe, Nandan

    2016-01-01

    The Profunda Femoris is a common site for arterial pseudo-aneurysms and these have been described in literature following fractures as well as orthopaedic procedures of the femur and hip region. These are an uncommon complication and a high index of suspicion is required for correct diagnosis and prompt management. We present a case of pseudo-aneurysm of the Profunda Femoris in an operated case of Intertrochanteric femur fracture with acute presentation. The case was managed successfully by angiographic coil embolization. PMID:27134957

  12. Eccentric and concentric isokinetic moment characteristics in the quadriceps and hamstrings of the chronic isolated posterior cruciate ligament injured knee

    PubMed Central

    MacLean, C. L.; Taunton, J. E.; Clement, D. B.; Regan, W.

    1999-01-01

    OBJECTIVE: Functional strength deficits associated with chronic isolated posterior cruciate ligament (PCL) insufficiency have received limited attention in the literature. The purpose of this study was to determine the eccentric and concentric isokinetic moment characteristics of the quadriceps and hamstrings in a sample of patients with isolated PCL injury. METHODS: Eccentric and concentric mean average and average peak moments were measured for 17 patients with a history of conservatively treated isolated PCL injury using an isokinetic dynamometer. Quadriceps and hamstring isokinetic moments were recorded from 10 degree to 90 degree of knee flexion. Strength ratios were calculated and compared with those reported in the literature for healthy subjects. RESULTS: The hamstrings of the involved side (eccentric/concentric (E/C) ratio = 1.06) were significantly weaker (p<0.05) eccentrically than those of the contralateral side (E/C ratio = 1.29). All hamstrings/quadriceps (H/Q) ratios were less than the universally accepted value of 0.60 and the eccentric H/Q ratio for the injured extremity was significantly lower than the non-injured (p<0.05). In a bilateral comparison, the injured/non-injured (I/N) ratio was less than 1.00 for concentric quadriceps, eccentric quadriceps, and hamstring isokinetic moments. Calculation of the E/C ratio showed that, for the quadriceps, it was 1.08 on the injured side and 1.07 on the non-injured extremity. CONCLUSIONS: Eccentric strengthening should be an integral part of functionally rehabilitating the quadriceps and hamstrings of athletes who suffer from the complications associated with chronic isolated PCL insufficiency. 


 PMID:10597850

  13. A model of dynamic sacro-iliac joint instability from malrecruitment of gluteus maximus and biceps femoris muscles resulting in low back pain.

    PubMed

    Hossain, M; Nokes, L D M

    2005-01-01

    The objective of this work is to propose a biomechanical model of sacro-iliac joint dysfunction as a cause of low back pain. Sacro-iliac joint is known to be a source of low back pain. We also know that it is a very stable joint with little mobility. Surrounding lower limb and back muscles contribute a major part of this stability. Gait analysis studies have revealed an orderly sequence of muscle activation when we walk - that contributes to efficient stabilisation of the joint and effective weight transfer to the lower limb. Gluteus maximus fibres-lying almost perpendicular to the joint surfaces are ideally oriented for this purpose. Biceps femoris is another important muscle that can also influence joint stability by its proximal attachment to sacrotuberous ligament. Altered pattern of muscle recruitment has been observed in patients with low back pain. But we do not know the exact cause-effect relationship. Because of its position as a key linkage in transmission of weight from the upper limbs to the lower, poor joint stability could have major consequences on weight bearing. It is proposed that sacro-iliac joint dysfunction can result from malrecruitment of gluteus maximus motor units during weight bearing. This results in compensatory biceps over activation. The resulting soft tissue strain and joint instability may manifest itself in low back pain. If our hypothesis holds true, it may have positive implications for patients with sacro-iliac joint dysfunction - who could be offered a definite diagnosis and targeted physiotherapy. It may be possible to identify patients early in a primary care setting and offer direct physio referral. They could benefit from exercises to improve strengthening and recruitment of the affected muscles.

  14. THE EFFECTS OF VARIED TENSIONS OF KINESIOLOGY TAPING ON QUADRICEPS STRENGTH AND LOWER LIMB FUNCTION

    PubMed Central

    Franco, Yuri Rafael dos Santos; Nannini, Stella Bispo; Nakaoka, Gustavo Bezerra; dos Reis, Amir Curcio; Bryk, Flavio Fernandes

    2017-01-01

    Background Kinesiology Taping (KT) may promote changes in muscle strength and motor performance, topics of great interest in the sports-medicine sciences. These characteristics are purported to be associated with the tension generated by the KT on the skin. However, the most suitable tension for the attainment of these strength and performance effects has not yet been confirmed. Hypothesis/Purpose The purpose of the present study was to analyze the effects of different tensions of KT on the isometric contraction of the quadriceps and lower limb function of healthy individuals over a period of seven days. Study Design Blind, randomized, clinical trial. Methods One hundred and thirty healthy individuals were distributed into the following five groups: control (without KT); KT0 (KT without tension); KT50; KT75 and KT100 (approximately 50%, 75% and 100% tension applied to the tape, respectively). Assessments of isometric quadriceps strength were conducted using a hand held dynamometer. Lower limb function was assessed through Single Hop Test for Distance, with five measurement periods: baseline; immediately after KT application; three days after KT; five days after KT; and 72h after KT removal (follow-up). Results There were no statistically significant differences (p > 0.05) at any of the studied periods on participants’ quadriceps strength nor in the function of the lower dominant limb, based on comparisons between the control group and the experimental groups. Conclusion KT applied with different tensions did not produce modulations, in short or long-term, on quadriceps’ strength or lower limb function of healthy individuals. Therefore, this type of KT application, when seeking these objectives, should be reconsidered. Level of Evidence 1b PMID:28217419

  15. The duration of the inhibitory effects with static stretching on quadriceps peak torque production.

    PubMed

    Siatras, Theophanis A; Mittas, Vasilios P; Mameletzi, Dimitra N; Vamvakoudis, Eystratios A

    2008-01-01

    Although several studies have investigated the acute effect of static stretching exercises, the duration of exercises that negatively affects performance has not been ascertained. This study was conducted to determine the acute effect of different static stretching durations on quadriceps isometric and isokinetic peak torque production. The 50 participants were randomly allocated into five equivalent sized groups and were asked to perform a stretching exercise of different duration (no stretch, 10-second stretch, 20-second stretch, 30-second stretch, and 60-second stretch). The knee flexion range of motion and the isometric and concentric isokinetic peak torques of the quadriceps were measured before and after a static stretching exercise in the four experimental groups. The same parameters were examined in the control group (no stretch) without stretching, before and after a 5-minute passive rest. There were no significant differences among groups before the experimentation regarding their physical characteristics and performances (P > 0.05). These results reflect the different groups' homogeneity. Significant knee joint flexibility increases (P < 0.001) and significant isometric and isokinetic peak torque reductions (P < 0.05-0.001) have been shown to occur only after 30 and 60 seconds of quadriceps static stretching. Stretching reduced isometric peak torque by 8.5% and 16.0%, respectively. Concerning isokinetic peak torque after 30 and 60 seconds of stretching, it was reduced by 5.5% vs. 11.6% at 60 degrees/s and by 5.8% vs. 10.0% at 180 degrees/s. We suggest that torque decrements are related to changes of muscle neuromechanical properties. It is recommended that static stretching exercises of a muscle group for more than 30 seconds of duration be avoided before performances requiring maximal strength.

  16. Effects of quadriceps and hamstrings proprioceptive neuromuscular facilitation stretching on knee movement sensation.

    PubMed

    Streepey, Jefferson W; Mock, Marla J; Riskowski, Jody L; Vanwye, William R; Vitvitskiy, Boris M; Mikesky, Alan E

    2010-04-01

    Stretching before competition has traditionally been thought to benefit performance; however, recent evidence demonstrating reduced muscle force and power immediately after stretching suggests otherwise. We hypothesized that knee joint position sense would be diminished immediately after proprioceptive neuromuscular facilitation (PNF) stretching to the hamstrings and quadriceps. Eighteen subjects (aged 18-30 years) were seated with their dominant foot attached to a motorized arm with the knee flexed at 135 degrees . To block external cues, the subjects wore a blindfold, earplugs, and headphones providing white noise. The knee was displaced in either the flexion or the extension direction at a velocity of 0.4 degrees .s, and subjects pressed a button when they sensed motion. The knee was returned to 135 degrees , and the test was repeated for a total of 10 trials. The PNF group received PNF stretching to the hamstrings and quadriceps of the dominant leg. The SHAM group had the dominant leg passively moved within each subject's functional range of motion. The ability to detect knee movement was retested in the PNF and SHAM groups. Pre- and posttest latencies between movement onset and subject response were analyzed. Results indicated that the PNF group had significantly increased latencies after stretching (from 2.56 +/- 0.83 to 3.46 +/- 1.90 seconds) compared with the SHAM group (3.93 +/- 2.40 to 3.72 +/- 2.15 seconds). It is concluded that PNF stretching of the hamstrings and quadriceps may acutely diminish sensitivity to knee movement. For coaches and trainers, these findings are consistent with previous reports of loss in muscle force and power immediately after stretching, suggesting that stretching just before competition may diminish performance.

  17. Deficits in Quadriceps Strength and Patient-Oriented Outcomes at Return to Activity After ACL Reconstruction

    PubMed Central

    Lepley, Lindsey K.

    2015-01-01

    Context: Side-to-side quadriceps strength deficits are linked to hazardous lower extremity mechanics and reduced function at a time when individuals are returned to activity after anterior cruciate ligament (ACL) reconstruction. As a result, generalized criteria have emerged in the literature, wherein researchers are recommending that patients be cleared for participation once side-to-side differences in strength are ≤10% of the noninjured limb. Similar recommendations exist for patient-oriented outcomes (ie, self-reported function and hop tests), where deficits of ≤10% are considered ideal at return to activity. It is unclear how many studies actually achieve these clinically recommended results. Evidence Acquisition: Articles that reported quadriceps strength deficits as compared to the contralateral limb were collected from peer-reviewed sources available on Medline and Web of Science databases (1990 through August 2014). Search terms included the following: anterior cruciate ligament OR ACL AND muscle weakness, anterior cruciate ligament OR ACL AND strength; return-to-activity AND strength; anterior cruciate ligament OR ACL AND quadriceps. Study Design: Clinical review. Level of Evidence: Level 4. Results: Average side-to-side strength deficits at 6 months postreconstruction were 23% ± 8% (range, 3%-40%), while the average at 12 months postsurgery was found to be 14% ± 6% (range, 3%-28%). The average deficits in self-reported function at 6 months (mean, 14% ± 5%) and 12 months postsurgery (mean, 13% ± 6%) were also found to be >10%. Performance on hop tests was found to be less than optimal at 6 months postsurgery (mean, 11% ± 7%), but improved at 12 months postsurgery (mean, 1.3% ± 2%). Conclusion: This review provides an up-to-date account of the typical deficits in strength and patient-oriented outcomes that exist when formalized physical therapy concludes after ACL reconstruction. Based on the studies included, it seems pertinent that researchers

  18. Differences in Gait Performance, Quadriceps Strength, and Physical Activity Between Fallers and Nonfallers in Women with Osteoporosis.

    PubMed

    Stief, Felix; Schäfer, Anna; Vogt, Lutz; Kirchner, Marietta; Hübscher, Markus; Thiel, Christian; Banzer, Winfried; Meurer, Andrea

    2016-07-01

    The present study should reveal differences in gait performance, quadriceps strength, and physical activity (PA) between fallers and nonfallers in women with osteoporosis. Forty-one women with osteoporosis (17 fallers, 24 nonfallers) participated. Gait analysis shows that fallers were walking with a slower walking speed (-9%, p = .033) and had a shorter stride length (-7%, p = .039). Moreover, fallers showed a decreased ankle power generation (-18%, p = .045). The quadriceps strength was decreased by 24% for fallers (p = .005) while PA showed no significant differences. Although a decrease in ankle power generation could have an effect on floor clearance for limb advancement in the swing phase, the causal relationship between spatiotemporal parameters (walking speed, stride length) and walking ankle joint power generation remains unknown and warrants further investigation. In conclusion, walking speed, stride length, ankle power generation, and quadriceps strength can be used to differentiate between fallers and nonfallers in women with osteoporosis.

  19. Floating patella: combined quadriceps tendon, retinacula, and patellar tendon ruptures in a high-performance elite athlete.

    PubMed

    Langer, Phillip R; Selesnick, F Harlan

    2010-09-01

    Simultaneous quadriceps and patellar tendon rupture is rare. To our knowledge, we present the first known case of simultaneous quadriceps tendon, patella tendon, and retinacula rupture in the ipsilateral knee of a high-performance elite athlete. This disabling injury in the active person results in an inability to actively obtain and maintain full knee extension. When the tendons do not heal properly, at the correct length and tension, knee range of motion and strength can become significantly altered, leading to early fatigue, patellofemoral pain, and possibly instability, preventing return to preinjury status. Immediate surgical repair is recommended for optimal return of knee function and power.

  20. Effect of endurance versus resistance training on quadriceps muscle dysfunction in COPD: a pilot study

    PubMed Central

    Iepsen, Ulrik Winning; Munch, Gregers Druedal Wibe; Rugbjerg, Mette; Rinnov, Anders Rasmussen; Zacho, Morten; Mortensen, Stefan Peter; Secher, Niels H; Ringbaek, Thomas; Pedersen, Bente Klarlund; Hellsten, Ylva; Lange, Peter; Thaning, Pia

    2016-01-01

    Introduction Exercise is an important countermeasure to limb muscle dysfunction in COPD. The two major training modalities in COPD rehabilitation, endurance training (ET) and resistance training (RT), may both be efficient in improving muscle strength, exercise capacity, and health-related quality of life, but the effects on quadriceps muscle characteristics have not been thoroughly described. Methods Thirty COPD patients (forced expiratory volume in 1 second: 56% of predicted, standard deviation [SD] 14) were randomized to 8 weeks of ET or RT. Vastus lateralis muscle biopsies were obtained before and after the training intervention to assess muscle morphology and metabolic and angiogenic factors. Symptom burden, exercise capacity (6-minute walking and cycle ergometer tests), and vascular function were also assessed. Results Both training modalities improved symptom burden and exercise capacity with no difference between the two groups. The mean (SD) proportion of glycolytic type IIa muscle fibers was reduced after ET (from 48% [SD 11] to 42% [SD 10], P<0.05), whereas there was no significant change in muscle fiber distribution with RT. There was no effect of either training modality on muscle capillarization, angiogenic factors, or vascular function. After ET the muscle protein content of phosphofructokinase was reduced (P<0.05) and the citrate synthase content tended increase (P=0.08) but no change was observed after RT. Conclusion Although both ET and RT improve symptoms and exercise capacity, ET induces a more oxidative quadriceps muscle phenotype, counteracting muscle dysfunction in COPD. PMID:27822028

  1. Effective therapy of transected quadriceps muscle in rat: Gastric pentadecapeptide BPC 157.

    PubMed

    Staresinic, Mario; Petrovic, Igor; Novinscak, Tomislav; Jukic, Ivana; Pevec, Damira; Suknaic, Slaven; Kokic, Neven; Batelja, Lovorka; Brcic, Luka; Boban-Blagaic, Alenka; Zoric, Zdenka; Ivanovic, Domagoj; Ajduk, Marko; Sebecic, Bozidar; Patrlj, Leonardo; Sosa, Tomislav; Buljat, Gojko; Anic, Tomislav; Seiwerth, Sven; Sikiric, Predrag

    2006-05-01

    We report complete transection of major muscle and the systemic peptide treatment that induces healing of quadriceps muscle promptly and then maintains the healing with functional restoration. Initially, stable gastric pentadecapeptide BPC 157 (GEPPPGKPADDAGLV, M.W. 1419, PL-10, PLD-116, PL 14736 Pliva, Croatia; in trials for inflammatory bowel disease; wound treatment; no toxicity reported; effective alone without carrier) also superiorly accelerates the healing of transected Achilles tendon. Regularly, quadriceps muscle completely transected transversely 1.0 cm proximal to patella presents a definitive defect that cannot be compensated in rat. BPC 157 (10 microg, 10 ng, 10 pg/kg) is given intraperitoneally, once daily; the first application 30 min posttransection, the final 24 h before sacrifice. It consistently improves muscle healing throughout the whole 72-day period. Improved are: (i) biomechanic (load of failure increased); (ii) function (walking recovery and extensor postural thrust/motor function index returned toward normal healthy values); (iii) microscopy/immunochemistry [i.e., mostly muscle fibers connect muscle segments; absent gap; significant desmin positivity for ongoing regeneration of muscle; larger myofibril diameters on both sides, distal and proximal (normal healthy rat-values reached)]; (iv) macroscopic presentation (stumps connected; subsequently, atrophy markedly attenuated; finally, presentation close to normal noninjured muscle, no postsurgery leg contracture). Thus, posttransection healing-consistently improved-may suggest this peptide therapeutic application in muscle disorders.

  2. Quadriceps activation and perceived exertion during a high intensity, steady state contraction to failure.

    PubMed

    Pincivero, D M; Gear, W S

    2000-04-01

    The ability to sustain a high-intensity, steady-state muscle contraction may have differential effects on neuromuscular activation and perceived exertion. The purpose of this study was to examine changes in neuromuscular activation and perceived exertion at a near-maximal steady-state contraction of the quadriceps in healthy men. Seventeen healthy, college-aged male volunteers were studied during isometric contractions equivalent to 80% of the maximum voluntary contraction (MVC). Perceived exertion was measured with a modified category-ratio scale (CR-10). The CR-10 scale was anchored with one high anchor at 100% MVC and one low anchor at 10% MVC. Subjects then performed an 80% MVC for as long as they could sustain it. Subjects were asked to rate the feelings in their quadriceps every 5 s during the contraction. The results demonstrated significant increases in neuromuscular activation of the vastus medialis and vastus lateralis muscles (P < 0.05) during the 80% MVC, but there were no significant muscle by time interactions. The results also demonstrated a significant increase (P < 0.05) in perceived exertion during the 80% MVC. Neuromuscular activation of both muscles, and perceived exertion, were found to increase in linear (P < 0.05) and quadratic (P < 0.05) trends. Alterations in motor unit discharge properties or impairments in muscle fiber membrane excitability may account for nonlinear increases in vastii muscle activation and perceived exertion.

  3. Quadriceps Contusion

    MedlinePlus

    ... En Español Making a Change – Your Personal Plan Hot Topics Am I in a Healthy Relationship? Who Can Get Weight ... a penalty called spearing), so make sure you don't do it to an opposing player. With skiing, snowboarding, and skateboarding, know your limits. Stay within your capabilities to decrease ...

  4. Quadriceps Contusion

    MedlinePlus

    ... And they can happen in sports like skateboarding, skiing, and snowboarding, where there is a chance your thigh might ... t do it to an opposing player. With skiing, snowboarding, and skateboarding, know your limits. Stay within ...

  5. Effect of a Periodized Power Training Program on the Functional Performances and Contractile Properties of the Quadriceps in Sprinters

    ERIC Educational Resources Information Center

    Kamandulis, Sigitas; Skurvydas, Albertas; Brazaitis, Marius; Stanislovaitis, Aleksas; Duchateau, Jacques; Stanislovaitiene, Jurate

    2012-01-01

    Our purpose was to compare the effect of a periodized preparation consisting of power endurance training and high-intensity power training on the contractile properties of the quadriceps muscle and functional performances in well trained male sprinters (n = 7). After 4 weeks of high-intensity power training, 60-m sprint running time improved by an…

  6. Comparison of Lower Body Specific Resistance Training on the Hamstring to Quadriceps Strength Ratios in Men and Women

    ERIC Educational Resources Information Center

    Dorgo, Sandor; Edupuganti, Pradeep; Smith, Darla R.; Ortiz, Melchor

    2012-01-01

    In this study, we compared hamstring (H) and quadriceps (Q) strength changes in men and women, as well as changes in conventional and functional H:Q ratios following an identical 12-week resistance training program. An isokinetic dynamometer was used to assess 14 male and 14 female participants before and after the intervention, and conventional…

  7. Neglected rupture of the quadriceps tendon in a patient with chronic renal failure (case report and review of the literature).

    PubMed

    Hassani, Zouhir Ameziane; Boufettal, Moncef; Mahfoud, Moustapha; Elyaacoubi, Moradh

    2014-01-01

    Spontaneous ruptures of the quadriceps tendon are infrequent injuries, it is seen primarily in patients with predisposing diseases such as gout, rheumatoid arthritis and chronic renal failure. A 32-year-old man had a history of end stage renal disease and received regular hemodialysis treatment for more than 5 years. He was admitted in our service for total functional impotence of the right lower limb with knee pain after a common fall two months ago. The radiogram showed a ''patella baja" with suprapatellar calcifications. The ultrasound and MRI showed an aspect of rupture of the quadriceps tendon in its proximal end with retraction of 3 cm. Quadriceps tendon repair was performed with a lengthening plasty, and the result was satisfactory after a serial rehabilitation program. The diagnosis of quadriceps tendon ruptures needs more attention in patients with predisposing diseases. They should not be unknown because the treatment of neglected lesions is more difficult. We insist on the early surgical repair associated with early rehabilitation that can guarantee recovery of good active extension.

  8. Contraction history affects the in vivo quadriceps torque-velocity relationship in humans.

    PubMed

    Rácz, Levente; Béres, Sándor; Hortobágyi, Tibor; Tihanyi, József

    2002-08-01

    We hypothesized that the history of contraction would affect the in vivo quadriceps torque-velocity relationship. We examined the quadriceps torque-velocity relationship of the human knee extensors at the descending and ascending limb of the torque-position relationship by initiating the knee extension at a knee angle position of 1.39 rad (80 degrees ) or 0.87 rad (50 degrees ) over a 0.52 rad (30 degrees ) range of motion under conditions of constant or linearly increasing velocity. Maximal voluntary isometric knee extension torque (M(0)) was measured at 1.87 rad, 0.87 rad, and 0.35 rad, and concentric torque was measured. The subjects carried out ten maximal knee extensions at ten distinct velocities, each velocity ranging between 0.52 rad x s(-1) to 5.24 rad x s(-1) in steps of 0.52 rad x s(-1). Peak concentric torque was measured and mean torque calculated from the respective torque-time curves. Peak or mean torque, computed from the individual torque-time curves, and velocity data were fitted to the Hill equation under the four experimental conditions and the curve parameters computed. The M(0) was similar at 0.87 rad and 1.39 rad, but it was significantly lower at 0.35 rad. In the low-velocity domain of the torque-velocity curve where a plateau normally occurs, peak torque was always lower than M(0). Peak and mean torque were significantly greater under linearly increasing velocity conditions and the 1.39 rad starting knee position. Mean torque but not peak torque data could be well fitted to the Hill equation and the two computations resulted in significantly different Hill curve parameters including the concavity ratio, peak power, and maximal angular velocity. We concluded that the history of contraction significantly modifies the in vivo torque-velocity relationship of the human quadriceps muscle. Muscle mechanics and not neural factors may have accounted for the inconsistencies in the human torque-velocity relationships reported previously.

  9. Hamstrings to quadriceps peak torque ratios diverge between sexes with increasing isokinetic angular velocity.

    PubMed

    Hewett, Timothy E; Myer, Gregory D; Zazulak, Bohdanna T

    2008-09-01

    Our purpose was to determine if females demonstrate decreased hamstrings to quadriceps peak torque (H/Q) ratios compared to males and if H/Q ratios increase with increased isokinetic velocity in both sexes. Maturation disproportionately increases hamstrings peak torque at high velocity in males, but not females. Therefore, we hypothesised that mature females would demonstrate decreased H/Q ratios compared to males and the difference in H/Q ratio between sexes would increase as isokinetic velocity increased. Studies that analysed the H/Q ratio with gravity corrected isokinetic strength testing reported between 1967 and 2004 were included in our review and analysis. Keywords were hamstrings/quadriceps, isokinetics, peak torque and gravity corrected. Medline and Smart databases were searched combined with cross-checked bibliographic reference lists of the publications to determine studies to be included. Twenty-two studies were included with a total of 1568 subjects (1145 male, 423 female). Males demonstrated a significant correlation between H/Q ratio and isokinetic velocity (R=0.634, p<0.0001), and a significant difference in the isokinetic H/Q ratio at the lowest angular velocity (47.8+/-2.2% at 30 degrees /s) compared to the highest velocity (81.4+/-1.1% at 360 degrees /s, p<0.001). In contrast, females did not demonstrate a significant relationship between H/Q ratio and isokinetic velocity (R=0.065, p=0.77) or a change in relative hamstrings strength as the speed increased (49.5+/-8.8% at 30 degrees /s; 51.0+/-5.7% at 360 degrees /s, p=0.84). Gender differences in isokinetic H/Q ratios were not observed at slower angular velocities. However, at high knee flexion/extension angular velocities, approaching those that occur during sports activities, significant gender differences were observed in the H/Q ratio. Females, unlike males, do not increase hamstrings to quadriceps torque ratios at velocities that approach those of functional activities.

  10. Acute effects of anterior thigh foam rolling on hip angle, knee angle, and rectus femoris length in the modified Thomas test.

    PubMed

    Vigotsky, Andrew D; Lehman, Gregory J; Contreras, Bret; Beardsley, Chris; Chung, Bryan; Feser, Erin H

    2015-01-01

    Background. Foam rolling has been shown to acutely increase range of motion (ROM) during knee flexion and hip flexion with the experimenter applying an external force, yet no study to date has measured hip extensibility as a result of foam rolling with controlled knee flexion and hip extension moments. The purpose of this study was to investigate the acute effects of foam rolling on hip extension, knee flexion, and rectus femoris length during the modified Thomas test. Methods. Twenty-three healthy participants (male = 7; female = 16; age = 22 ± 3.3 years; height = 170 ± 9.18 cm; mass = 67.7 ± 14.9 kg) performed two, one-minute bouts of foam rolling applied to the anterior thigh. Hip extension and knee flexion were measured via motion capture before and after the foam rolling intervention, from which rectus femoris length was calculated. Results. Although the increase in hip extension (change = +1.86° (+0.11, +3.61); z(22) = 2.08; p = 0.0372; Pearson's r = 0.43 (0.02, 0.72)) was not due to chance alone, it cannot be said that the observed changes in knee flexion (change = -1.39° (-5.53, +2.75); t(22) = -0.70; p = 0.4933; Cohen's d = - 0.15 (-0.58, 0.29)) or rectus femoris length (change = -0.005 (-0.013, +0.003); t(22) = -1.30; p = 0.2070; Cohen's d = - 0.27 (-0.70, 0.16)) were not due to chance alone. Conclusions. Although a small change in hip extension was observed, no changes in knee flexion or rectus femoris length were observed. From these data, it appears unlikely that foam rolling applied to the anterior thigh will improve passive hip extension and knee flexion ROM, especially if performed in combination with a dynamic stretching protocol.

  11. Selective lengthening of the psoas and rectus femoris and preservation of the iliacus for flexion deformity of the hip in cerebral palsy patients.

    PubMed

    Matsuo, T; Hara, H; Tada, S

    1987-01-01

    Between 1978 and 1983, 52 Japanese patients with cerebral palsy underwent operative correction of flexion deformity of the hip. The results of lengthening of the psoas, rectus femoris, and proximal hamstrings were satisfactory. The iliacus was left intact. Improvement in gait and activities of daily living was attained. Concentric reduction was obtained in 27 of 33 dislocated or subluxated hips. Sitting and perineal care were facilitated, and pain was alleviated. We conclude that preservation of the iliacus is important.

  12. Femoral quadriceps neuromuscular electrical stimulation after total knee arthroplasty: a systematic review

    PubMed Central

    Volpato, Helena Bruna Bettoni; Szego, Paulo; Lenza, Mario; Milan, Silvia Lefone; Talerman, Claudia; Ferretti, Mario

    2016-01-01

    ABSTRACT The purpose of this study was to evaluate the effects of neuromuscular electrical stimulation in patients submitted to total knee arthroplasty. This was a systematic review with no language or publication status restriction. Our search was made in Cochrane Library, MEDLINE, Embase and LILACS. Randomized or quasi-randomized clinical trials evaluating neuromuscular electrical stimulation after total knee arthroplasty were included. Four studies with moderate risk of bias and low statistical power were included, totalizing 376 participants. There was no statistically significant difference in knee function, pain and range of motion during 12 month follow-up. This review concluded that neuromuscular electrical stimulation was less effective than traditional rehabilitation in function, muscular strength and range of motion. However, this technique was useful for quadriceps activation during the first days after surgery. PMID:26537511

  13. Development of estimation system of knee extension strength using image features in ultrasound images of rectus femoris

    NASA Astrophysics Data System (ADS)

    Murakami, Hiroki; Watanabe, Tsuneo; Fukuoka, Daisuke; Terabayashi, Nobuo; Hara, Takeshi; Muramatsu, Chisako; Fujita, Hiroshi

    2016-04-01

    The word "Locomotive syndrome" has been proposed to describe the state of requiring care by musculoskeletal disorders and its high-risk condition. Reduction of the knee extension strength is cited as one of the risk factors, and the accurate measurement of the strength is needed for the evaluation. The measurement of knee extension strength using a dynamometer is one of the most direct and quantitative methods. This study aims to develop a system for measuring the knee extension strength using the ultrasound images of the rectus femoris muscles obtained with non-invasive ultrasonic diagnostic equipment. First, we extract the muscle area from the ultrasound images and determine the image features, such as the thickness of the muscle. We combine these features and physical features, such as the patient's height, and build a regression model of the knee extension strength from training data. We have developed a system for estimating the knee extension strength by applying the regression model to the features obtained from test data. Using the test data of 168 cases, correlation coefficient value between the measured values and estimated values was 0.82. This result suggests that this system can estimate knee extension strength with high accuracy.

  14. The physical and biochemical changes in springbok (Antidorcas marsupialis) Longissimus thoracis et lumborum and Biceps femoris muscle during ageing.

    PubMed

    North, M K; Frylinck, L; Hoffman, L C

    2015-12-01

    This study aimed to determine the optimum ageing period for vacuum-packed springbok (Antidorcas marsupialis) Longissimus thoracis et lumborum (LTL) and Biceps femoris (BF) muscle stored at 5.4 ± 1.0°C. Portions of muscle from seven male and six female springbok were aged 1, 2, 5, 8, 14 or 21 days. The Warner Bratzler shear force declined most during the first five days post-mortem (PM), while purge and cooking losses increased significantly with ageing. Calpains I and II and calpastatin activity declined significantly up to five days PM, suggesting that they may be responsible for tenderization. Cathepsins B, BL and H activity increased significantly during ageing. The BF muscle had significantly higher pH, lower purge loss, higher cooking loss, higher WBSF and higher calpain and calpastatin activity than the LTL. No significant differences between the genders or muscles were found for the collagen content or collagen solubility. Springbok LTL and BF muscles should not be aged for longer than five days.

  15. Neuromuscular efficiency of the vastus lateralis and biceps femoris muscles in individuals with anterior cruciate ligament injuries☆

    PubMed Central

    Aragão, Fernando Amâncio; Schäfer, Gabriel Santo; de Albuquerque, Carlos Eduardo; Vituri, Rogério Fonseca; de Azevedo, Fábio Mícolis; Bertolini, Gladson Ricardo Flor

    2015-01-01

    Objective To analyze strength and integrated electromyography (IEMG) data in order to determine the neuromuscular efficiency (NME) of the vastus lateralis (VL) and biceps femoris (BF) muscles in patients with anterior cruciate ligament (ACL) injuries, during the preoperative and postoperative periods; and to compare the injured limb at these two times, using the non-operated limb as a control. Methods EMG data and BF and VL strength data were collected during three maximum isometric contractions in knee flexion and extension movements. The assessment protocol was applied before the operation and two months after the operation, and the NME of the BF and VL muscles was obtained. Results There was no difference in the NME of the VL muscle from before to after the operation. On the other hand, the NME of the BF in the non-operated limb was found to have increased, two months after the surgery. Conclusions The NME provides a good estimate of muscle function because it is directly related to muscle strength and capacity for activation. However, the results indicated that two months after the ACL reconstruction procedure, at the time when loading in the open kinetic chain within rehabilitation protocols is usually started, the neuromuscular efficiency of the VL and BF had still not been reestablished. PMID:26229914

  16. The changes in springbok (Antidorcas marsupialis) Longissimus thoracis et lumborum and Biceps femoris muscles during the rigour period.

    PubMed

    North, M K; Frylinck, L; Hoffman, L C

    2016-02-01

    This study describes the changes taking place during rigour in springbok (Antidorcas marsupialis) Longissimus thoracis et lumborum (LTL) and Biceps femoris (BF) muscles. Samples from six male and six female springbok were snap-frozen at 2, 3, 5, 8, 12, 18, 24 and 30h post-mortem (PM) and the pH, calpains I, II and calpastatin activities and cathepsins B, BL and H activities were determined. The temperature was also recorded. Significant third-order interactions were found for the pH and temperature, with the female LTL cooling more rapidly and acidifying slower than the other samples. Female muscles were at risk of developing cold-shortening and all the samples cooled more rapidly than recommended for cattle or sheep. Cathepsin BL activity increased PM, likely due to the degradation of the lysosomes. Calpains I, II and calpastatin activity declined during rigour, indicating that the calpains were activated early PM. Gender and muscle had a significant effect on calpain and cathepsin activity.

  17. A Comparison of Gluteus Maximus, Biceps Femoris, and Vastus Lateralis Electromyographic Activity in the Back Squat and Barbell Hip Thrust Exercises.

    PubMed

    Contreras, Bret; Vigotsky, Andrew D; Schoenfeld, Brad J; Beardsley, Chris; Cronin, John

    2015-12-01

    The back squat and barbell hip thrust are both popular exercises used to target the lower body musculature; however, these exercises have yet to be compared. Therefore, the purpose of this study was to compare the surface electromyographic (EMG) activity of the upper and lower gluteus maximus, biceps femoris, and vastus lateralis between the back squat and barbell hip thrust. Thirteen trained women (n = 13; age = 28.9 years; height = 164 cm; mass = 58.2 kg) performed estimated 10-repetition maximums (RM) in the back squat and barbell hip thrust. The barbell hip thrust elicited significantly greater mean (69.5% vs 29.4%) and peak (172% vs 84.9%) upper gluteus maximus, mean (86.8% vs 45.4%) and peak (216% vs 130%) lower gluteus maximus, and mean (40.8% vs 14.9%) and peak (86.9% vs 37.5%) biceps femoris EMG activity than the back squat. There were no significant differences in mean (99.5% vs 110%) or peak (216% vs 244%) vastus lateralis EMG activity. The barbell hip thrust activates the gluteus maximus and biceps femoris to a greater degree than the back squat when using estimated 10RM loads. Longitudinal training studies are needed to determine if this enhanced activation correlates with increased strength, hypertrophy, and performance.

  18. Trunk muscle action compensates for reduced quadriceps force during walking after total knee arthroplasty.

    PubMed

    Li, Katherine; Ackland, David C; McClelland, Jodie A; Webster, Kate E; Feller, Julian A; de Steiger, Richard; Pandy, Marcus G

    2013-05-01

    Patients with total knee arthroplasty (TKA) frequently exhibit changes in gait biomechanics post-surgery, including decreased ranges of joint motion and changes in joint loading; however, the actions of the lower-limb muscles in generating joint moments and accelerating the center of mass (COM) during walking are yet to be described. The aim of the present study was to evaluate differences in lower-limb joint kinematics, muscle-generated joint moments, and muscle contributions to COM accelerations in TKA patients and healthy age-matched controls when both groups walk at the same speed. Each TKA patient was fitted with a posterior-stabilized total knee replacement and underwent patellar resurfacing. Three-dimensional gait analysis and subject-specific musculoskeletal modeling were used to determine lower-limb and trunk muscle forces and muscle contributions to COM accelerations during the stance phase of gait. The TKA patients exhibited a 'quadriceps avoidance' gait pattern, with the vasti contributing significantly less to the extension moment developed about the knee during early stance (p=0.036). There was a significant decrease in the contribution of the vasti to the vertical acceleration (support) (p=0.022) and forward deceleration of the COM (braking) (p=0.049) during early stance; however, the TKA patients compensated for this deficiency by leaning their trunks forward. This significantly increased the contribution of the contralateral back extensor muscle (erector spinae) to support (p=0.030), and that of the contralateral back rotators (internal and external obliques) to braking (p=0.004). These findings provide insight into the biomechanical causes of post-operative gait adaptations such as 'quadriceps avoidance' observed in TKA patients.

  19. Motor adaptations to unilateral quadriceps fatigue during a bilateral pedaling task.

    PubMed

    Brøchner Nielsen, N-P; Hug, F; Guével, A; Fohanno, V; Lardy, J; Dorel, S

    2016-12-20

    This study was designed to investigate how motor coordination adapts to unilateral fatigue of the quadriceps during a constant-load bilateral pedaling task. We first hypothesized that this local fatigue would not be compensated within the fatigued muscles leading to a decreased knee extension power. Then, we aimed to determine whether this decrease would be compensated by between-joints compensations within the ipsilateral leg and/or an increased contribution of the contralateral leg. Fifteen healthy volunteers were tested during pedaling at 350 W before and after a fatigue protocol consisting of 15 minutes of electromyostimulation on the quadriceps muscle. Motor coordination was assessed from myoelectrical activity (22 muscles) and joint powers calculated through inverse dynamics. Maximal knee extension torque decreased by 28.3%±6.8% (P<.0005) immediately after electromyostimulation. A decreased knee extension power produced by the ipsilateral leg was observed during pedaling (-22.8±12.3 W, -17.0%±9.4%; P<.0005). To maintain the task goal, participants primarily increased the power produced by the non-fatigued contralateral leg during the flexion phase. This was achieved by an increase in hip flexion power confirmed by a higher activation of the tensor fascia latae. These results suggest no adjustment of neural drive to the fatigued muscles and demonstrate no concurrent ipsilateral compensation by the non-fatigued muscles involved in the extension pedaling phase. Although interindividual variability was observed, findings provide evidence that participants predominantly adapted by compensating with the contralateral leg during its flexion phase. Both neural (between legs) and mechanical (between pedals) couplings and the minimization of cost functions might explain these results.

  20. Quadriceps muscle blood flow and oxygen availability during repetitive bouts of isometric exercise in simulated sailing.

    PubMed

    Vogiatzis, Ioannis; Andrianopoulos, Vasileios; Louvaris, Zafeiris; Cherouveim, Evgenia; Spetsioti, Stavroula; Vasilopoulou, Maroula; Athanasopoulos, Dimitrios

    2011-07-01

    In this study, we wished to determine whether the observed reduction in quadriceps muscle oxygen availability, reported during repetitive bouts of isometric exercise in simulated sailing efforts (i.e. hiking), is because of restricted muscle blood flow. Six national-squad Laser sailors initially performed three successive 3-min hiking bouts followed by three successive 3-min cycling tests sustained at constant intensities reproducing the cardiac output recorded during each of the three hiking bouts. The blood flow index (BFI) was determined from assessment of the vastus lateralis using near-infrared spectroscopy in association with the light-absorbing tracer indocyanine green dye, while cardiac output was determined from impedance cardiography. At equivalent cardiac outputs (ranging from 10.3±0.5 to 14.8±0.86 L · min(-1)), the increase from baseline in vastus lateralis BFI across the three hiking bouts (from 1.1±0.2 to 3.1±0.6 nM · s(-1)) was lower (P = 0.036) than that seen during the three cycling bouts (from 1.1±0.2 to 7.2±1.4 nM · s(-1)) (Cohen's d: 3.80 nM · s(-1)), whereas the increase from baseline in deoxygenated haemoglobin (by ∼17.0±2.9 μM) (an index of tissue oxygen extraction) was greater (P = 0.006) during hiking than cycling (by ∼5.3±2.7 μM) (Cohen's d: 4.17 μM). The results suggest that reduced vastus lateralis muscle oxygen availability during hiking arises from restricted muscle blood flow in the isometrically acting quadriceps muscles.

  1. Decision rules for egg recognition are related to functional roles and chemical cues in the queenless ant Dinoponera quadriceps

    NASA Astrophysics Data System (ADS)

    Tannure-Nascimento, Ivelize C.; Nascimento, Fabio S.; Dantas, José O.; Zucchi, Ronaldo

    2009-07-01

    The capacity to distinguish colony members from strangers is a key component in social life. In social insects, this extends to the brood and involves discrimination of queen eggs. Chemical substances communicate colony affiliation for both adults and brood; thus, in theory, all colony members should be able to recognize fellow nestmates. In this study, we investigate the ability of Dinoponera quadriceps workers to discriminate nestmate and non-nestmate eggs based on cuticular hydrocarbon composition. We analyzed whether cuticular hydrocarbons present on the eggs provide cues of discrimination. The results show that egg recognition in D. quadriceps is related to both age and the functional role of workers. Brood care workers were able to distinguish nestmate from non-nestmate eggs, while callow and forager workers were unable to do so.

  2. Does Cruciate-Retaining Total Knee Arthroplasty Show Better Quadriceps Recovery than Posterior-Stabilized Total Knee Arthroplasty? - Objective Measurement with a Dynamometer in 102 Knees

    PubMed Central

    Cho, Kye-Youl; Song, Sang-Jun; Bae, Dae-Kyung

    2016-01-01

    Background Cruciate-retaining (CR) prostheses have been considered to produce more physiologic femoral rollback, provide better proprioception, and result in better quadriceps recovery than posterior-stabilized (PS) prostheses after total knee arthroplasty (TKA). However, there are very few studies demonstrating these benefits in an objective manner. We investigated whether CR-TKA could result in (1) better quadriceps recovery; (2) a greater proportion of patients with beyond the preoperative level of recovery; and (3) better clinical outcomes than PS-TKA. Methods This was a prospective non-randomized comparative study on the results of CR-TKA and PS-TKA. CR prostheses were used in 51 knees and PS prostheses in 51 knees. Quadriceps force was measured with a dynamometer preoperatively and at postoperative 6 weeks, 3 months, and 6 months consecutively. The Knee Society score (KSS) and range of motion (ROM) were also evaluated. Results There were no differences between two groups in terms of the objective quadriceps force during the follow-up period. The proportion of patients with beyond the preoperative level of recovery was similar between groups. Moreover, the KSS and ROM were not significantly different between two groups. Conclusions CR-TKA did not result in better quadriceps recovery than PS-TKA during the 6-month follow-up. In other words, PS-TKA could lead to comparable quadriceps recovery despite greater preoperative weaknesses such as more restricted ROM and more severe degenerative changes of the knee. PMID:27904719

  3. The relationship between isokinetic quadriceps strength and laxity on gait analysis parameters in anterior cruciate ligament reconstructed knees.

    PubMed

    Gokeler, Alli; Schmalz, Thomas; Knopf, Elmar; Freiwald, Jürgen; Blumentritt, Siegmar

    2003-11-01

    Gait alterations after ACL reconstruction have been reported in the literature. The current study examined a group of 14 patients who all had an ACL reconstruction with a patellar tendon autograft. Kinetic and kinematic data were obtained from the knee during walking. The flexion-extension deficit (FED) calculated from the angular difference between maximal flexion and maximal extension during the stance phase in the ACL-reconstructed and the normal knee was measured. We investigated whether these alterations in gait are related to quadriceps strength and residual laxity of the knee. It may be that patients modify their gait patterns to protect the knee from excessive anterior translation of the tibia by reducing the amount of extension during stance. On the other hand, persistent quadriceps weakness may also cause changes in gait patterns as the quadriceps is functioning as an important dynamic stabilizer of the knee during stance. Results showed that patients had a significantly higher FED value (4.9+/-4.0) than a healthy control group in a previous study (1.3+/-0.9). This is caused mainly by an extension deficit during midstance. External extension moments of the knee (TZMAX were significantly lower in the current patients group than in a healthy control group (TZMAX -0.27+/-0.19 Nm/kg in patients vs. -0.08+/-0.06 Nm/kg in controls). There were no significant correlations between quadriceps strength and gait analysis parameters. Furthermore no correlation was found between the amount of laxity of the knee and gait. The relevance of this study lies in the fact that apparently the measured gait alterations cannot be explained solely by often used biomechanical indicators such as laxity and strength. The measured gait alterations may be a result of the surgical procedure with subsequent modified motor programming.

  4. Anticonvulsant Effects of Fractions Isolated from Dinoponera quadriceps (Kempt) Ant Venom (Formicidae: Ponerinae)

    PubMed Central

    Nôga, Diana Aline Morais Ferreira; Brandão, Luiz Eduardo Mateus; Cagni, Fernanda Carvalho; Silva, Delano; de Azevedo, Dina Lilia Oliveira; Araújo, Arrilton; dos Santos, Wagner Ferreira; Miranda, Antonio; da Silva, Regina Helena; Ribeiro, Alessandra Mussi

    2016-01-01

    Natural products, sources of new pharmacological substances, have large chemical diversity and architectural complexity. In this context, some toxins obtained from invertebrate venoms have anticonvulsant effects. Epilepsy is a neurological disorder that affects about 65 million people worldwide, and approximately 30% of cases are resistant to pharmacological treatment. Previous studies from our group show that the denatured venom of the ant Dinoponera quadriceps (Kempt) protects mice against bicuculline (BIC)-induced seizures and death. The aim of this study was to investigate the anticonvulsant activity of compounds isolated from D. quadriceps venom against seizures induced by BIC in mice. Crude venom was fractionated by high-performance liquid chromatography (HPLC) resulting in six fractions referred to as DqTx1–DqTx6. A liquid chromatography-mass spectrometry (LC/MS) analysis revealed a major 431 Da compound in fractions DqTx1 and DqTx2. Fractions DqTx3 and DqTx4 showed a compound of 2451 Da and DqTx5 revealed a 2436 Da compound. Furthermore, the DqTx6 fraction exhibited a major component with a molecular weight of 13,196 Da. Each fraction (1 mg/mL) was microinjected into the lateral ventricle of mice, and the animals were observed in an open field. We did not observe behavioral alterations when the fractions were given alone. Conversely, when the fractions were microinjected 20 min prior to the administration of BIC (21.6 nM), DqTx1, DqTx4, and DqTx6 fractions increased the latency for onset of tonic-clonic seizures. Moreover, all fractions, except DqTx5, increased latency to death. The more relevant result was obtained with the DqTx6 fraction, which protected 62.5% of the animals against tonic-clonic seizures. Furthermore, this fraction protected 100% of the animals from seizure episodes followed by death. Taken together, these findings indicate that compounds from ant venom might be a potential source of new anticonvulsants molecules. PMID:28025529

  5. Anticonvulsant Effects of Fractions Isolated from Dinoponera quadriceps (Kempt) Ant Venom (Formicidae: Ponerinae).

    PubMed

    Nôga, Diana Aline Morais Ferreira; Brandão, Luiz Eduardo Mateus; Cagni, Fernanda Carvalho; Silva, Delano; de Azevedo, Dina Lilia Oliveira; Araújo, Arrilton; Dos Santos, Wagner Ferreira; Miranda, Antonio; da Silva, Regina Helena; Ribeiro, Alessandra Mussi

    2016-12-23

    Natural products, sources of new pharmacological substances, have large chemical diversity and architectural complexity. In this context, some toxins obtained from invertebrate venoms have anticonvulsant effects. Epilepsy is a neurological disorder that affects about 65 million people worldwide, and approximately 30% of cases are resistant to pharmacological treatment. Previous studies from our group show that the denatured venom of the ant Dinoponera quadriceps (Kempt) protects mice against bicuculline (BIC)-induced seizures and death. The aim of this study was to investigate the anticonvulsant activity of compounds isolated from D. quadriceps venom against seizures induced by BIC in mice. Crude venom was fractionated by high-performance liquid chromatography (HPLC) resulting in six fractions referred to as DqTx1-DqTx6. A liquid chromatography-mass spectrometry (LC/MS) analysis revealed a major 431 Da compound in fractions DqTx1 and DqTx2. Fractions DqTx3 and DqTx4 showed a compound of 2451 Da and DqTx5 revealed a 2436 Da compound. Furthermore, the DqTx6 fraction exhibited a major component with a molecular weight of 13,196 Da. Each fraction (1 mg/mL) was microinjected into the lateral ventricle of mice, and the animals were observed in an open field. We did not observe behavioral alterations when the fractions were given alone. Conversely, when the fractions were microinjected 20 min prior to the administration of BIC (21.6 nM), DqTx1, DqTx4, and DqTx6 fractions increased the latency for onset of tonic-clonic seizures. Moreover, all fractions, except DqTx5, increased latency to death. The more relevant result was obtained with the DqTx6 fraction, which protected 62.5% of the animals against tonic-clonic seizures. Furthermore, this fraction protected 100% of the animals from seizure episodes followed by death. Taken together, these findings indicate that compounds from ant venom might be a potential source of new anticonvulsants molecules.

  6. Dynamics of corticospinal changes during and after high-intensity quadriceps exercise.

    PubMed

    Gruet, Mathieu; Temesi, John; Rupp, Thomas; Levy, Patrick; Verges, Samuel; Millet, Guillaume Y

    2014-08-01

    This study tested the hypothesis that during fatiguing quadriceps exercise, supraspinal fatigue develops late, is associated with both increased corticospinal excitability and inhibition and recovers quickly. Eight subjects performed 20 s contractions [15 s at 50% maximal voluntary contraction (MVC) followed by 5 s MVC] separated by a 10 s rest period until task failure. Transcranial magnetic stimulation (TMS) and electrical femoral nerve stimulation (PNS) were delivered ∼ 2 s apart during 50% MVC, during MVC and after MVC in relaxed muscle. Voluntary activation was assessed by TMS (VATMS) immediately before and after exercise and then three times over a 6 min recovery period. During exercise, MVC and twitch force evoked by PNS in relaxed muscle decreased progressively to 48 ± 8 and 36 ± 16% of control values, respectively (both P < 0.01). Significant changes in voluntary activation assessed by PNS and twitch evoked by TMS during MVC were observed during the last quarter of exercise only (from 96.4 ± 1.7 to 86 ± 13%, P = 0.03 and from 0.76 ± 0.8 to 4.9 ± 4.7% MVC, P = 0.02, from baseline to task failure, respectively). The TMS-induced silent period increased linearly during both MVC (by ∼ 79 ms) and 50% MVC (by ∼ 63 ms; both P < 0.01). Motor-evoked potential amplitude did not change during the protocol at any force levels. Both silent period and VATMS recovered within 2 min postexercise, whereas MVC and twitch force evoked by PNS in relaxed muscle recovered to only 84 ± 9 and 73 ± 17% of control values 6 min after exercise, respectively. In conclusion, high-intensity single-joint quadriceps exercise induces supraspinal fatigue near task failure, with increased intracortical inhibition and, in contrast to previous upper-limb results, unchanged corticospinal excitability. These changes recover rapidly after task failure, emphasizing the need to measure corticospinal adaptations immediately at task failure to avoid underestimation of exercise

  7. Anterior cruciate ligament reconstruction using quadriceps tendon autograft for adolescents with open physes- a technical note

    PubMed Central

    2011-01-01

    Background One major concern in the treatment of ACL lesions in children and adolescents with open physes is the risk of iatrogenic damage to the physes and a possibly resulting growth disturbance. Purpose The primary purpose of this article is to describe our technique of a transphyseal ACL reconstruction using quadriceps tendon-bone autograft in children and adolescents with open growth plates. The secondary aim is to report our early results in terms of postoperative growth disturbances which are considered to be a major concern in this challenging group of patients. It was our hypothesis that with our proposed technique no significant growth disturbances would occur. Methods From January 1997 to December 2007 49 consecutive children and adolescents with open growth plates were treated for a torn ACL using the aforementioned surgical technique. The patients (28 males and 21 females) with a median age at surgery of 13 (range 8-15) years were retrospectively evaluated. Outcome measures were follow-up radiographs (weight-bearing long leg radiographs of the injured and uninjured knee, anteroposterior and lateral views, a tangential view of the patella and a tunnel view of the injured knee) and follow-up notes (6 weeks, 3, 6, 12 months and until closing of physes) for occurrence of any tibial and/or femoral growth changes. Results: All of the 49 patients had a sufficient clinical and radiological follow-up (minimum 5 years, rate 100%). 48 cases did not show any clinical and radiological growth disturbance. One case of growth disturbance in a 10.5 years old girl was observed. She developed a progressive valgus-flexion deformity which was attributed to a malplacement of the autograft bone block within the femoral posterolateral epiphyseal plate leading to an early localized growth stop. None of the patients were reoperated due to ACL graft failure. Five of the patients underwent revision ACL surgery due to another adequate sports trauma after the growth-stop. The

  8. Effects of Kinesio Tape application to quadriceps muscles on isokinetic muscle strength, gait, and functional parameters in patients with stroke.

    PubMed

    Ekiz, Timur; Aslan, Meryem Doğan; Özgirgin, Neşe

    2015-01-01

    The aim of this study was to evaluate the effects of Kinesio Tape (KT) application to quadriceps muscles on isokinetic muscle strength, gait, and functional parameters in patients with stroke. Twenty-four patients were allocated into KT and control groups. All patients participated in the same conventional rehabilitation program 5 times/wk for 4 wk. In addition, KT was applied to quadriceps muscles bilaterally to the patients in the KT group. Compared with baseline, peak torque levels increased significantly in both groups (all p < 0.05). However, change levels were significantly higher in the KT group than the control group at 60 degrees/second angular velocity (AV) in extension (p = 0.04) and 60 and 180 degrees/second AV in flexion (both p = 0.02) on the paretic side. Moreover, the change levels were more prominent in the KT group at 60 and 180 degrees/second AV in extension (p = 0.03 and p = 0.04, respectively) on the nonparetic side. Gait, balance, mobility, and quality of life values improved significantly in both groups (all p < 0.05), yet the change levels between the groups did not reach significance (p > 0.05). KT application to quadriceps muscles in addition to conventional exercises for 4 wk is effective on isokinetic but not functional parameters.

  9. Kinesio Taping Does Not Alter Quadriceps Isokinetic Strength and Power in Healthy Nonathletic Men: A Prospective Crossover Study

    PubMed Central

    Korman, Paweł; Straburzyńska-Lupa, Anna; Rutkowski, Radosław; Gruszczyński, Jakub; Lewandowski, Jacek; Straburzyński-Lupa, Marcin; Łochyński, Dawid

    2015-01-01

    Objectives. The effects of Kinesio Taping (KT) on muscular performance remain largely unclear. This study aimed to investigate the acute effects of KT on the maximum concentric and eccentric quadriceps isokinetic strength. Study Design. This is a single-blinded, placebo crossover, repeated measures study. Methods. Maximum isokinetic concentric/eccentric extension torque, work, and power were assessed by an isokinetic dynamometer without taping (NT) and with KT or placebo taping (PT) in 17 healthy young men. Repeated measures one-way analysis of variance (ANOVA) was used for statistical analyses. Results. Testing concentric contractions at 60°/s or 180°/s isokinetic speed, no significant differences in peak torque (Nm), total work (J), or mean power (W) were noted among the application modes under different conditions. Testing eccentric contractions at 30°/s or 60°/s isokinetic speed, no significant differences in mentioned parameters were noted, respectively. KT on the quadriceps neither decreased nor increased muscle strength in the participants. Conclusion. KT application onto the skin overlying the quadriceps muscle does not enhance the strength or power of knee extensors in healthy men. PMID:26819953

  10. Postural response to vibration of triceps surae, but not quadriceps muscles, differs between people with and without knee osteoarthritis.

    PubMed

    Shanahan, Camille J; Wrigley, Tim V; Farrell, Michael J; Bennell, Kim L; Hodges, Paul W

    2014-08-01

    Although proprioceptive impairments are reported in knee osteoarthritis (OA), there has been little investigation of the underlying causes. Muscle spindles make an important contribution to proprioception. This study investigated whether function of quadriceps, triceps surae, and tibialis anterior muscle spindles is altered in individuals with knee OA. Thirty individuals with knee OA (17 females, 66 ± 7 [mean ± SD] years) and 30 healthy asymptomatic controls (17 females, 65 ± 8 years) stood comfortably and blindfolded on a force plate. Mechanical vibration (60 Hz) was applied bilaterally over the quadriceps, triceps surae, or tibialis anterior muscles for the middle 15 s (Vibration) of a 45 s trial (preceded and followed by 15 s Baseline and Recovery periods). Two trials were recorded for each muscle site. Mean anterior-posterior displacement of centre of pressure was analysed. Although there were no differences between groups for trials with vibration applied to the quandriceps or tibialis anterior, participants with knee OA were initially perturbed more by triceps surae vibration and accommodated less to repeated exposure than controls. This indicates that people with knee OA have less potential to detect or compensate for disturbed input to triceps surae, possibly due to an inability to compensate using muscles spindles in the quadriceps muscle.

  11. Effects of isometric quadriceps strength training at different muscle lengths on dynamic torque production.

    PubMed

    Noorkõiv, Marika; Nosaka, Kazunori; Blazevich, Anthony J

    2015-01-01

    This study aims to (1) determine whether isometric training at a short vs. long quadriceps muscle length affects concentric torque production; (2) examine the relationship between muscle hypertrophy and concentric torque; and (3) determine whether changes in fascicle length are associated with changes in concentric torque. Sixteen men performed isometric training at a short (SL, n = 8) or a long muscle length (LL, n = 8). Changes in maximal concentric torque were measured at 30, 60, 90, 120, 180, 240 and 300 rad · s(-1). The relationships between the changes in concentric torque, cross-sectional area, volume and fascicle length were tested. Concentric torque increased significantly after training only in LL and at angular velocities of 30 and 120 rad · s(-1) by 12-13% (P < 0.05). Muscle size increased in LL only, the changes were correlated (r = 0.73-0.93, P < 0.05) with the changes in concentric torque. Vastus lateralis (VL) fascicle length increased in both groups (5.4 ± 4.9%, P = 0.001) but the change was not correlated with changes in concentric torque in either group. Isometric training-induced increases in muscle size and concentric torque were best elicited by training at long muscle lengths. These results highlight a clear muscle length dependence of isometric training on dynamic torque production.

  12. Can the Use of Neuromuscular Electrical Stimulation Be Improved to Optimize Quadriceps Strengthening?

    PubMed Central

    Glaviano, Neal R.; Saliba, Susan

    2016-01-01

    Context: Neuromuscular electrical stimulation (NMES) is a common modality used to retrain muscles and improve muscular strength after injury or surgery, particularly for the quadriceps muscle. There are parameter adjustments that can be made to maximize the effectiveness of NMES. While NMES is often used in clinical practice, there are some limitations that clinicians should be aware of, including patient discomfort, muscle fatigue, and muscle damage. Evidence Acquisition: PubMed was searched through August 2014 and all articles cross-referenced. Study Design: Clinical review. Level of Evidence: Level 3. Results: Clinicians can optimize torque production and decrease discomfort by altering parameter selection (pulse duration, pulse frequency, duty cycle, and amplitude). Pulse duration of 400 to 600 µs and a pulse frequency of 30 to 50 Hz appear to be the most effective parameters to optimize torque output while minimizing discomfort, muscle fatigue, or muscle damage. Optimal electrode placement, conditioning programs, and stimulus pattern modulation during long-term NMES use may improve results. Conclusion: Torque production can be enhanced while decreasing patient discomfort and minimizing fatigue. PMID:26582349

  13. Immediate Effects of Kinesiology Taping of Quadriceps on Motor Performance after Muscle Fatigued Induction

    PubMed Central

    Ahn, Ick Keun; Kim, You Lim; Bae, Young-Hyeon; Lee, Suk Min

    2015-01-01

    Objectives. The purpose of this cross-sectional single-blind study was to investigate the immediate effects of Kinesiology taping of quadriceps on motor performance after muscle fatigued induction. Design. Randomized controlled cross-sectional design. Subjects. Forty-five subjects participated in this study. Participants were divided into three groups: Kinesiology taping group, placebo taping group, and nontaping group. Methods. Subjects performed short-term exercise for muscle fatigued induction, followed by the application of each intervention. Peak torque test, one-leg single hop test, active joint position sense test, and one-leg static balance test were carried out before and after the intervention. Results. Peak torque and single-leg hopping distance were significantly increased when Kinesiology taping was applied (p < 0.05). But there were no significant effects on active joint position sense and single-leg static balance. Conclusions. We proved that Kinesiology taping is effective in restoring muscle power reduced after muscle fatigued induction. Therefore, we suggest that Kinesiology taping is beneficial for fatigued muscles. PMID:26246835

  14. QUADRICEPS LOW FREQUENCY FATIGUE AND MUSCLE PAIN ARE CONTRACTION TYPE DEPENDENT

    PubMed Central

    Iguchi, Masaki; Shields, Richard K.

    2010-01-01

    Introduction Eccentric contractions are thought to induce greater low frequency fatigue (LFF) and delayed onset muscle soreness (DOMS) than concentric contractions. This study induced a similar amount of eccentric quadriceps muscle fatigue during either a concentric or eccentric fatigue task to compare LFF and DOMS. Methods Subjects (n=22) performed concentric or eccentric fatigue tasks using 75% of the pre-fatigue maximal voluntary contraction (MVC) torque, and both tasks ended when the MVC eccentric torque decreased by 25% pre-fatigue. Results When subjects reached the failure criterion during the eccentric and concentric tasks, the concentric MVC was 78 ± 9.8% and 64 ± 8.4% of initial, respectively. LFF was greater after the concentric than the eccentric protocols (22 ± 12.4% and 15 ± 7.6% increase, respectively; p < 0.01). DOMS was over 100% greater for the eccentric protocol. Discussion These results indicate that DOMS is not dependent on the events that contribute to LFF. PMID:20544933

  15. Alterations in quadriceps and hamstrings coordination in persons with medial compartment knee osteoarthritis.

    PubMed

    Zeni, Joseph A; Rudolph, Katherine; Higginson, Jill S

    2010-02-01

    Altered muscle coordination strategies in persons with knee osteoarthritis (OA) result in an increase in co-contraction of the quadriceps and hamstrings during walking. While this may increase intersegmental joint contact force and expedite disease progression, it is not currently known whether the magnitude of co-contraction increases with a progressive loss of joint space or whether the level of co-contraction is dependent on walking speed. The purposes of this study were to (1) determine if co-contraction increased with OA severity and (2) discern whether differences in co-contraction were a result of altered freely chosen walking speeds or rather an inherent change associated with disease progression. Forty-two subjects with and without knee osteoarthritis were included in the study. Subjects were divided into groups based on disease severity. When walking at a controlled speed of 1.0m/s, subjects with moderate and severe knee OA showed significantly higher co-contraction when compared to a healthy control group. At freely chosen walking speeds only the moderate OA group had significantly higher co-contraction values. Increased walking speed also resulted in a significant increase in co-contraction, regardless of group. The results of this study demonstrate that persons with knee OA develop higher antagonistic muscle activity. This occurs despite differences in freely chosen walking speed. Although subjects with OA had higher co-contraction than the control group, co-contraction may not increase with disease severity.

  16. Human quadriceps strength and fatiguability in patients with post viral fatigue.

    PubMed Central

    Rutherford, O M; White, P D

    1991-01-01

    Quadriceps isometric strength, activation and fatiguability were measured in 11 patients with symptoms of fatigue three months after glandular fever or a glandular fever-like illness. Predicted normal and lower limits of normal muscle strength were calculated from height and age. These measures and the fatigue index were compared with a group of healthy students of similar age. Two of the patients were unable to activate fully their muscles. After allowing for this inhibition the group mean (SD) strength was 104 (22%) of predicted. Although there was no significant difference in the fatigue index between the patients and the control group, there was a trend for the patients to show less fatigue than controls. There was no difference in the muscle results for those patients who were found to have Epstein-Barr virus infections and those who did not. The feelings of weakness and fatigue experienced by the patients could not be explained by either physiological muscle fatigue or lack of effort. PMID:1800667

  17. Outcomes after quadriceps tendon repair in patients over 80 years of age

    PubMed Central

    Ellanti, Prasad; Moriarty, Andrew; Nagle, Matthew; McCarthy, Tom

    2016-01-01

    Summary Background Quadriceps tendon (QT) ruptures are uncommon and mostly occur in those who are 50–60 years of age. Timely surgical repair can result in a good functional outcome, however, little is known about the outcome in the older patient. Methods A retrospective review of all QT ruptures between 2009 and 2014 was conducted. Patients over the age of 80 were included. Those with penetrating trauma or partial ruptures were excluded. A chart review was undertaken to gather demographic and operative details. The patients were contacted by phone or by mail to have Lysholm and Rougraff scores completed. Results Of the 32 QT ruptures identified, 6 (19%) patients were eligible for inclusion in our study. They were predominantly (83%) males with a mean age of 81.38 years. The mean follow up was 54 months. The mean Lysholm score at last follow up was 84.8/100, which falls within the range of a good outcome. The mean Rougraff score was 21.3/25, which is an excellent outcome. All patients felt they were close to their premorbid level of mobility. Conclusion Good outcomes can be expected with QT repair in older patients, resulting in restoration of the pre-injury level of mobility. Level of evidence: Level V case series. PMID:27900296

  18. Hamstrings-to-quadriceps strength and size ratios of male professional soccer players with muscle imbalance.

    PubMed

    Denadai, Benedito Sérgio; de Oliveira, Felipe Bruno Dias; Camarda, Sérgio Ricardo de Abreu; Ribeiro, Leandro; Greco, Camila Coelho

    2016-03-01

    The aim of this study was to determine the correlation between the concentric hamstrings/quadriceps muscle strength (Hcon :Qcon ) and cross-sectional area ratios (Hcsa :Qcsa ) in professional soccer players with Hcon :Qcon imbalance. Nine male professional soccer players (25·3 ± 4·1 years) performed five maximal concentric contractions of the knee extensors (KE) and flexors (KF) at 60 s(-1) to assess Hcon :Qcon . The test was performed using the dominant (preferred kicking), and non-dominant limb with a 5-min recovery period was allowed between them. Only players with Hcon :Qcon < 0·60 (range: 0·45-0·59) in both limbs were included in this study. The muscle cross-sectional area (CSA) of KE and KF was determined by magnetic resonance imaging. The correlations between Hcon :Qcon and Hcsa :Qcsa in the dominant leg (r = -0·33), non-dominant leg (r = 0·19) and in the both legs combined (r = 0·28) were not statistically significant (P>0·05). Thus, the Hcon :Qcon seems not to be determined by Hcsa :Qcsa in professional soccer players with Hcon :Qcon imbalance.

  19. Isokinetic concentric quadriceps and hamstring normative data for elite collegiate American football players participating in the NFL Scouting Combine.

    PubMed

    Zvijac, John E; Toriscelli, Todd A; Merrick, W Shannon; Papp, Derek F; Kiebzak, Gary M

    2014-04-01

    Isokinetic concentric quadriceps and hamstring strength data using a Cybex dynamometer are collected for elite collegiate American football players invited to the annual National Football League Scouting Combine. We constructed a normative (reference) database of the Cybex strength data for the purpose of allowing comparison of an individual's values to his peers. Data reduction was performed to construct frequency distributions of hamstring/quadriceps (H/Q) ratios and side-to-side strength differences. For the cohort (n = 1,252 players), a statistically significant but very small (1.9%) mean quadriceps strength preference existed for dominant side vs. nondominant side. Peak torque (Newton meters, best repetition) for quadriceps and hamstrings was significantly correlated to player body mass (weight) (the same relationship was found for other variables using peak torque in the calculation). Peak torque varied by player position, being greatest for offensive linemen and lowest for kickers (p < 0.0001). Adjusting for body weight overcorrected these differences. The H/Q ratios and frequency distributions were similar across positions, with a mean of 0.6837 ± 0.137 for the cohort dominant side vs. 0.6940 ± 0.145 for the nondominant side (p = 0.021, n = 1,252). Considerable variation was seen for dominant-to-nondominant side difference for peak torque. For quadriceps, 47.2% of players had differences between -10% and +10%, 21.0% had a peak torque dominant-side deficit of 10% or greater compared to nondominant side, and for 31.8% of players, dominant-side peak torque was greater than 10% compared to nondominant side. For hamstrings, 57.0% of players had differences between -10% and +10%, 19.6% had a peak torque dominant-side deficit of 10% or greater compared to nondominant side, and 23.4% of players, dominant-side peak torque was greater than 10% compared to nondominant side. We observed that isokinetic absolute strength variables are dependent on body weight and vary

  20. Acute effects of anterior thigh foam rolling on hip angle, knee angle, and rectus femoris length in the modified Thomas test

    PubMed Central

    Lehman, Gregory J.; Contreras, Bret; Beardsley, Chris; Chung, Bryan; Feser, Erin H.

    2015-01-01

    Background. Foam rolling has been shown to acutely increase range of motion (ROM) during knee flexion and hip flexion with the experimenter applying an external force, yet no study to date has measured hip extensibility as a result of foam rolling with controlled knee flexion and hip extension moments. The purpose of this study was to investigate the acute effects of foam rolling on hip extension, knee flexion, and rectus femoris length during the modified Thomas test. Methods. Twenty-three healthy participants (male = 7; female = 16; age = 22 ± 3.3 years; height = 170 ± 9.18 cm; mass = 67.7 ± 14.9 kg) performed two, one-minute bouts of foam rolling applied to the anterior thigh. Hip extension and knee flexion were measured via motion capture before and after the foam rolling intervention, from which rectus femoris length was calculated. Results. Although the increase in hip extension (change = +1.86° (+0.11, +3.61); z(22) = 2.08; p = 0.0372; Pearson’s r = 0.43 (0.02, 0.72)) was not due to chance alone, it cannot be said that the observed changes in knee flexion (change = −1.39° (−5.53, +2.75); t(22) = −0.70; p = 0.4933; Cohen’s d = − 0.15 (−0.58, 0.29)) or rectus femoris length (change = −0.005 (−0.013, +0.003); t(22) = −1.30; p = 0.2070; Cohen’s d = − 0.27 (−0.70, 0.16)) were not due to chance alone. Conclusions. Although a small change in hip extension was observed, no changes in knee flexion or rectus femoris length were observed. From these data, it appears unlikely that foam rolling applied to the anterior thigh will improve passive hip extension and knee flexion ROM, especially if performed in combination with a dynamic stretching protocol. PMID:26421244

  1. Endoscopic Extra-articular Surgical Removal of Heterotopic Ossification of the Rectus Femoris Tendon in a Series of Athletes

    PubMed Central

    Comba, Fernando; Piuzzi, Nicolás S.; Oñativia, José Ignacio; Zanotti, Gerardo; Buttaro, Martín; Piccaluga, Francisco

    2016-01-01

    Background: Calcific deposits in tendon, muscles, and periarticular areas are very common. Heterotopic ossification of the rectus femoris (HORF) is a rare condition, and several theories exist regarding the etiopathogenesis, which appears to be multifactorial with traumatic, genetic, and local metabolic factors involved. Although HORF typically responds to nonoperative treatment, when this approach fails, endoscopic treatment is a minimally invasive technique to address the pathology. Purpose: To report the clinical and radiological outcomes of 9 athletes with HORF who underwent endoscopic resection. Study Design: Case series; Level of evidence, 4. Methods: Nine male athletes were treated with endoscopic extra-articular resection of HORF after failure of a 6-month course of nonoperative treatment. All patients were studied with radiographs, computed tomography, and magnetic resonance imaging. Outcomes were assessed clinically using the modified Harris Hip Score (mHHS), a visual analog scale for sport activity–related pain (VAS-SRP), patient satisfaction, and ability and time to return to the preoperative sport level. Radiographic assessment was performed to determine recurrence. Results: The mean age of the patients was 32 years (range, 23-47 years). Mean follow-up was 44 months (range, 14-73 months). All patients had improved mHHS scores from a mean preoperative of 65.6 (SD, 8.2) to 93.9 (SD, 3.6). Pain decreased from a mean 8.2 preoperatively (SD, 0.9) to 0.4 (SD, 0.7) at last follow-up. There were no complications, and all patients were able to return to their previous sports at the same level except for 1 recreational athlete. There was only 1 radiological recurrence at last follow-up in an asymptomatic patient. Conclusion: To our knowledge, this is the largest case series of athletes with HORF treated with endoscopic resection. We found this extra-articular endoscopic technique to be safe and effective, showing clinical outcome improvement and 90% chance of

  2. Effects of aging and freezing/thawing sequence on quality attributes of bovine Mm. gluteus medius and biceps femoris

    PubMed Central

    Kim, Hyun-Wook; Brad Kim, Yuan H.

    2017-01-01

    Objective The effects of aging and freezing/thawing sequence on color, physicochemical, and enzymatic characteristics of two beef muscles (Mm. gluteus medius, GM and biceps femoris, BF) were evaluated. Methods Beef muscles at 3 d postmortem were assigned to four different combinations of aging and freezing/thawing sequence as follows; aging at 2°C for 3 wk (A3, never-frozen control), freezing at −28°C for 2 wk then thawing (F2, frozen/thawed-only), aging at 2°C for 3 wk, freezing at −28°C for 2 wk then thawing (A3F2), and freezing at −28°C for 2 wk, thawing then further aging at 2°C for 3 wk (F2A3). Results No significant interactions between different aging/freezing/thawing treatments and muscle type on all measurements were found. Postmortem aging, regardless of aging/freezing/thawing sequence, had no impact on color stability of frozen/thawed beef muscles (p<0.05). F2A3 resulted in higher purge loss than F2 and A3F2 treatments (p<0.05). A3F2 and F2A3 treatments resulted in lower shear force of beef muscles compared to F2 (p<0.05). Although there was no significant difference in glutathione peroxidase (GSH-Px) activity, F2A3 had the highest β-N-acetyl glucominidase (BNAG) activity in purge, but the lowest BNAG activity in muscle (p<0.05). GM muscle exhibited higher total color changes and purge loss, and lower GSH-Px activity than BF muscle. Conclusion The results from this present study indicate that different combinations of aging/freezing/thawing sequence would result in considerable impacts on meat quality attributes, particularly thaw/purge loss and tenderness. Developing a novel freezing strategy combined with postmortem aging will be beneficial for the food/meat industry to maximize its positive impacts on tenderness, while minimizing thaw/purge loss of frozen/thawed meat. PMID:27488843

  3. Core decompression or quadratus femoris muscle pedicle bone grafting for nontraumatic osteonecrosis of the femoral head: A randomized control study

    PubMed Central

    Li, Deqiang; Li, Ming; Liu, Peilai; Zhang, Yuankai; Ma, Liang; Xu, Fei

    2016-01-01

    Background: The traditional management for osteonecrosis of the femoral head (ONFH) includes core decompression (CD) and quadratus femoris muscle pedicle bone graft (QF-MPBG). The aim of this study was to investigate the effects of CD and QF-MPBG on the patients with nontraumatic ONFH in an early stage. Materials and Methods: 39 patients (47 hips) with ONFH in an early stage (Ficat Stage I or II) were randomly divided into two groups according to random number table method. One group was treated with CD and cancellous bone grafting. Another group was treated QF-MPBG with cancellous bone grafting. The hip function was evaluated using Harris hip score (HHS). The repair of the femoral head was estimated through X-ray, computed tomography (CT), or magnetic resonance imaging (MRI). The surgical time and intraoperative blood loss was calculated. Results: All patients were followed for an average 2.5 years (range from 1.5 to 4 years). Two hips in CD group progressed into stage 3 and three hips in QF-MPBG group processed into stage 3. No patient accepted the THA at the last followup. The HHSs significantly increased in both groups after surgery (P < 0.05). No statistical differences were found between CD and QF-MPBG groups in postoperative HHSs at last followup (P > 0.05). X-ray and CT showed that the femoral head did not progress to collapse after operation in both groups. In addition, MRI showed that the edema signals decreased. However, the surgical time was longer in QF-MPBG group than that in CD group (P < 0.05). The intraoperative blood loss was more in QF-MPBG than that in CD group (P < 0.05). Conclusion: The CD with bone graft could relieve hip pain, improve hip function with much lesser surgical trauma compared to QF-MPBG. Hence, the CD with bone graft should be generally used for the treatment of patients with an early stage (Ficat Stage I or II) ONFH. PMID:27904218

  4. Chronic eccentric cycling improves quadriceps muscle structure and maximum cycling power.

    PubMed

    Leong, C H; McDermott, W J; Elmer, S J; Martin, J C

    2014-06-01

    An interesting finding from eccentric exercise training interventions is the presence of muscle hypertrophy without changes in maximum concentric strength and/or power. The lack of improvements in concentric strength and/or power could be due to long lasting suppressive effects on muscle force production following eccentric training. Thus, improvements in concentric strength and/or power might not be detected until muscle tissue has recovered (e. g., several weeks post-training). We evaluated alterations in muscular structure (rectus-femoris, RF, and vastus lateralis, VL, thickness and pennation angles) and maximum concentric cycling power (Pmax) 1-week following 8-weeks of eccentric cycling training (2×/week; 5-10.5 min; 20-55% of Pmax). Pmax was assessed again at 8-weeks post-training. At 1 week post-training, RF and VL thickness increased by 24±4% and 13±2%, respectively, and RF and VL pennation angles increased by 31±4% and 13±1%, respectively (all P<0.05). Compared to pre-training values, Pmax increased by 5±1% and 9±2% at 1 and 8 weeks post-training, respectively (both P<0.05). These results demonstrate that short-duration high-intensity eccentric cycling can be a time-effective intervention for improving muscular structure and function in the lower body of healthy individuals. The larger Pmax increase detected at 8-weeks post-training implies that sufficient recovery might be necessary to fully detect changes in muscular power after eccentric cycling training.

  5. Quadriceps neuromuscular function and self-reported functional ability in knee osteoarthritis.

    PubMed

    Berger, M J; McKenzie, C A; Chess, D G; Goela, A; Doherty, T J

    2012-07-01

    The purposes of this study were to determine 1) the relationships of self-reported function scores in patients with knee osteoarthritis (OA) to both maximal isometric torque and to isotonic power at a variety of loads, and 2) the degree to which muscle volume (MV) or voluntary activation (VA) are associated with torque and power measures in this population. Isometric maximal voluntary contraction (MVC) torque and isotonic power [performed at loads corresponding to 10, 20, 30, 40, and 50% MVC, and a minimal load ("Zero Load")] were measured in 40 participants with knee OA. Functional ability was measured with the Western Ontario and McMaster Osteoarthritis Index (WOMAC) function subscale. MV was determined with magnetic resonance imaging, and VA was measured with the interpolated twitch technique. In general, power measured at lower loads (Zero Load and 10-30% MVC, r(2) = 0.21-0.28, P < 0.05) predicted a greater proportion of the variance in function than MVC torque (r(2) = 0.18, P < 0.05), with power measured at Zero Load showing the strongest association (r(2) = 0. 28, P < 0.05). MV was the strongest predictor of MVC torque and power measures in multiple regression models (r(2) = 0.42-0.72). VA explained only 6% of the variance in MVC torque and was not significantly associated with power at any load (P > 0.05). Quadriceps MVC torque and power are associated with self-reported function in knee OA, but muscle power at lower loads is more predictive of function than MVC torque. The variance in MVC torque and power between participants is due predominantly to differences in MV and has little to do with deficits in VA.

  6. Effect of a simulated soccer match on the functional hamstrings-to-quadriceps ratio in amateur female players.

    PubMed

    Delextrat, A; Baker, J; Cohen, D D; Clarke, N D

    2013-08-01

    The purpose of this study was to investigate the effect of a simulated soccer test on the functional hamstrings-to-quadriceps ratio (H(ecc) : Q(con)) in female soccer players. Fourteen amateur players (age, 26.1 ± 4.6 years; height, 168 ± 12 cm; body mass, 62.7 ± 5.5 kg; body fat, 23.7 ± 2.2%) performed the modified Loughborough Intermittent Shuttle Test (modified LIST). Isokinetic strength assessments of the hamstrings and quadriceps on the dominant and non-dominant legs at 120°/s were performed before and immediately after the modified LIST. H(ecc) : Q(con) was calculated as the ratio of the peak eccentric torque of the hamstrings to the peak concentric torque of the quadriceps. A two-way univariate analysis of variance was used to assess the effect of time and leg dominance on H(ecc) : Q(con). The main results showed that the modified LIST led to a significant decrease in H(ecc) : Q(con) in the dominant (-14.1%) and non-dominant legs (-8.0%) (P = 0.02). However, this decrease was not significantly different between dominant and non-dominant legs (P = 0.42). These results reflect a greater risk of hamstrings tears and ACL sprains at the end of soccer matches.

  7. Angle-specific hamstring-to-quadriceps ratio: a comparison of football players and recreationally active males.

    PubMed

    Evangelidis, Pavlos Eleftherios; Pain, Matthew Thomas Gerard; Folland, Jonathan

    2015-01-01

    It is currently unclear how football participation affects knee-joint muscle balance, which is widely considered a risk factor for hamstrings injury. This study compared the angle-specific functional hamstring-to-quadriceps (H:Q) ratio (hamstrings eccentric torque as a ratio of quadriceps concentric torque at the same knee-joint angle) of football players with recreationally active controls. Ten male footballers and 14 controls performed maximal voluntary isometric and isovelocity concentric and eccentric contractions (60, 240 and 400° s(-1)) of the knee extensors and flexors. Gaussian fitting to the raw torque values was used to interpolate torque values for knee-joint angles of 100-160° (60° s(-1)), 105-160° (240° s(-1)) and 115-145° (400° s(-1)). The angle-specific functional H:Q ratio was calculated from the knee flexors eccentric and knee extensors concentric torque at the same velocity and angle. No differences were found for the angle-specific functional H:Q ratio between groups, at any velocity. Quadriceps and hamstrings strength relative to body mass of footballers and controls was similar for all velocities, except concentric knee flexor strength at 400° s(-1) (footballers +40%; P < 0.01). In previously uninjured football players, there was no intrinsic muscle imbalance and therefore the high rate of hamstring injuries seen in this sport may be due to other risk factors and/or simply regular exposure to a high-risk activity.

  8. Superior results with eccentric compared to concentric quadriceps training in patients with jumper's knee: a prospective randomised study

    PubMed Central

    Jonsson, P; Alfredson, H

    2005-01-01

    Background: A recent study reported promising clinical results using eccentric quadriceps training on a decline board to treat jumper's knee (patellar tendinosis). Methods: In this prospective study, athletes (mean age 25 years) with jumper's knee were randomised to treatment with either painful eccentric or painful concentric quadriceps training on a decline board. Fifteen exercises were repeated three times, twice daily, 7 days/week, for 12 weeks. All patients ceased sporting activities for the first 6 weeks. Age, height, weight, and duration of symptoms were similar between groups. Visual analogue scales (VAS; patient estimation of pain during exercise) and Victorian Institute of Sport Assessment (VISA) scores, before and after treatment, and patient satisfaction, were used for evaluation. Results: In the eccentric group, for 9/10 tendons patients were satisfied with treatment, VAS decreased from 73 to 23 (p<0.005), and VISA score increased from 41 to 83 (p<0.005). In the concentric group, for 9/9 tendons patients were not satisfied, and there were no significant differences in VAS (from 74 to 68, p<0.34) and VISA score (from 41 to 37, p<0.34). At follow up (mean 32.6 months), patients in the eccentric group were still satisfied and sports active, but all patients in the concentric group had been treated surgically or by sclerosing injections. Conclusions: In conclusion, eccentric, but not concentric, quadriceps training on a decline board, seems to reduce pain in jumper's knee. The study aimed to include 20 patients in each group, but was stopped at the half time control because of poor results achieved in the concentric group. PMID:16244196

  9. Quadriceps and patellar tendon pie-crusting as a treatment for limited flexion in total knee arthroplasty.

    PubMed

    Burge, J Ross; Sanchez, Hugo B; Wagner, Russell A

    2014-04-01

    The pie-crusting method of ligament and tendon lengthening has been used successfully in various tissues but is not reported in the literature as an option for patellar or quadriceps tendons to address flexion limitation. Our case report discusses a patient with longstanding flexion limitation who underwent primary total knee arthroplasty. The report reviews the literature on intraoperative treatments, which primarily pertains to the condition of patella baja, and demonstrates that the pie-crusting technique should be included as a treatment option for a tight extensor mechanism while having some advantages over tibial tubercle osteotomy or Z-plasty.

  10. Transcriptome Analysis in Venom Gland of the Predatory Giant Ant Dinoponera quadriceps: Insights into the Polypeptide Toxin Arsenal of Hymenopterans

    PubMed Central

    Chong, Cheong-Meng; Leung, Siu Wai; Prieto-da-Silva, Álvaro R. B.; Havt, Alexandre; Quinet, Yves P.; Martins, Alice M. C.; Lee, Simon M. Y.; Rádis-Baptista, Gandhi

    2014-01-01

    Background Dinoponera quadriceps is a predatory giant ant that inhabits the Neotropical region and subdues its prey (insects) with stings that deliver a toxic cocktail of molecules. Human accidents occasionally occur and cause local pain and systemic symptoms. A comprehensive study of the D. quadriceps venom gland transcriptome is required to advance our knowledge about the toxin repertoire of the giant ant venom and to understand the physiopathological basis of Hymenoptera envenomation. Results We conducted a transcriptome analysis of a cDNA library from the D. quadriceps venom gland with Sanger sequencing in combination with whole-transcriptome shotgun deep sequencing. From the cDNA library, a total of 420 independent clones were analyzed. Although the proportion of dinoponeratoxin isoform precursors was high, the first giant ant venom inhibitor cysteine-knot (ICK) toxin was found. The deep next generation sequencing yielded a total of 2,514,767 raw reads that were assembled into 18,546 contigs. A BLAST search of the assembled contigs against non-redundant and Swiss-Prot databases showed that 6,463 contigs corresponded to BLASTx hits and indicated an interesting diversity of transcripts related to venom gene expression. The majority of these venom-related sequences code for a major polypeptide core, which comprises venom allergens, lethal-like proteins and esterases, and a minor peptide framework composed of inter-specific structurally conserved cysteine-rich toxins. Both the cDNA library and deep sequencing yielded large proportions of contigs that showed no similarities with known sequences. Conclusions To our knowledge, this is the first report of the venom gland transcriptome of the New World giant ant D. quadriceps. The glandular venom system was dissected, and the toxin arsenal was revealed; this process brought to light novel sequences that included an ICK-folded toxins, allergen proteins, esterases (phospholipases and carboxylesterases), and lethal

  11. The effect of mild symptomatic patellar tendinopathy on the quadriceps contractions and the Fente motion in elite fencers

    PubMed Central

    Kim, Taegyu; Kim, Eunkuk; Park, Jongchul; Kang, Hyunyong

    2011-01-01

    To investigate how mild symptomatic patellar tendinopathy (PT) affects quadriceps contractions and the Fente motion, this case-control study examined elite fencers who continue to train and play fully with mild tendon pains. Twenty-four elite fencers (10 women) with mild symptomatic PT and 24 controls (10 women) participated in the study. Concentric/eccentric isokinetic strength of the quadriceps was tested, and peak torque and total work were recorded. Kinematic data from the knee during the Fente motion were collected. The first analysis period (P1) was after heel contact to the maximal flexion of the knee, and the second (P2) was right after P1 to heel-off. Normalized peak torque and work of concentric/eccentric contractions were not significantly different. Affected fencers demonstrated significantly reduced angular velocities at P2 (p = 0.042). The male fencers did not demonstrate any differences. The affected female fencers demonstrated significantly weaker concentric peak torque at 60°·s-1 (p = 0. 009) and 180°·s-1 (p = 0.047) and less concentric work at 60°·s-1 (p = 0.020). They also demonstrated significantly reduced average angular velocities at P2 (p = 0.001). Therefore, mild symptomatic PT seems to have an effect on the isokinetic concentric contraction of the quadriceps and the angular velocity of the knee during the backward Fente motion in elite female fencers who are participating fully in training and competition. Key points It is likely that even mild symptomatic patellar tendinopathy could affect the athletic performances in elite fencers. Elite female fencers are more likely to be affected substantially by symptomatic patellar tendinopathy in their sporting ability than male fencers. Because weak concentric knee extensors may affect the performance in fencing, not only eccentric training for symptomatic patellar tendinopathy but also proper concentric training of the quadriceps may be helpful in a rehabilitation program of elite female

  12. Effects of quadriceps strength after static and dynamic whole-body vibration exercise.

    PubMed

    Bush, Jill A; Blog, Gabriel L; Kang, Jie; Faigenbaum, Avery D; Ratamess, Nicholas A

    2015-05-01

    Numerous studies have shown performance benefits including whole-body vibration (WBV) as a training modality or an acute exercise protocol when used as a component of the resistance training program. Some studies have indicated that performing dynamic exercises as compared with static position exercises while exposed to WBV might be beneficial; however, evidence is lacking. Thus, the purpose of this study was to determine if an acute bout of dynamic versus static squats performed during WBV results in increase in quadriceps force production by means of dynamic isokinetic knee extension and flexion exercise. Nonresistance-trained healthy young men and women (N = 21) of 18-25 years participated in 4 protocols with 2-week rest in-between. Protocol 1 consisted of 5 sets of 10 dynamic squats without vibration; Protocol 2: 5 sets of 30-second static squats without vibration; Protocol 3: 5 sets of 10 dynamic squats with 30-Hz WBV for a total of 2.5 minutes; and Protocol 4: 5 sets of 30-second static squats with 30-Hz WBV for a total of 2.5 minutes. Prestrength tests (1 set of 4 repetitions at 100° · s(-1) for the knee extension exercise) was performed within 5 minutes of starting each protocol, and poststrength testing was performed within 1 minute of completing each protocol. Strength outcomes were analyzed by repeated measures analysis of variance with a significance level set at p ≤ 0.05. A significant decrease in strength was observed after dynamic and static squats without WBV (p = 0.002); an increase in strength after dynamic squats with WBV (p = 0.003); and a decrease in strength after static squats with WBV (p = 0.003). The inclusion of WBV to dynamic resistance exercise can be an added modality to increase strength. Whole-body vibration can have varied effects in altering muscle strength in untrained individuals according to the type of resistance training performed. As a dynamic squat with WBV seems to immediately potentiate neuromuscular functioning, the

  13. Knee and Hip Joint Kinematics Predict Quadriceps and Hamstrings Neuromuscular Activation Patterns in Drop Jump Landings

    PubMed Central

    Malfait, Bart; Dingenen, Bart; Smeets, Annemie; Staes, Filip; Pataky, Todd; Robinson, Mark A.; Vanrenterghem, Jos; Verschueren, Sabine

    2016-01-01

    Purpose The purpose was to assess if variation in sagittal plane landing kinematics is associated with variation in neuromuscular activation patterns of the quadriceps-hamstrings muscle groups during drop vertical jumps (DVJ). Methods Fifty female athletes performed three DVJ. The relationship between peak knee and hip flexion angles and the amplitude of four EMG vectors was investigated with trajectory-level canonical correlation analyses over the entire time period of the landing phase. EMG vectors consisted of the {vastus medialis(VM),vastus lateralis(VL)}, {vastus medialis(VM),hamstring medialis(HM)}, {hamstring medialis(HM),hamstring lateralis(HL)} and the {vastus lateralis(VL),hamstring lateralis(HL)}. To estimate the contribution of each individual muscle, linear regressions were also conducted using one-dimensional statistical parametric mapping. Results The peak knee flexion angle was significantly positively associated with the amplitudes of the {VM,HM} and {HM,HL} during the preparatory and initial contact phase and with the {VL,HL} vector during the peak loading phase (p<0.05). Small peak knee flexion angles were significantly associated with higher HM amplitudes during the preparatory and initial contact phase (p<0.001). The amplitudes of the {VM,VL} and {VL,HL} were significantly positively associated with the peak hip flexion angle during the peak loading phase (p<0.05). Small peak hip flexion angles were significantly associated with higher VL amplitudes during the peak loading phase (p = 0.001). Higher external knee abduction and flexion moments were found in participants landing with less flexed knee and hip joints (p<0.001). Conclusion This study demonstrated clear associations between neuromuscular activation patterns and landing kinematics in the sagittal plane during specific parts of the landing. These findings have indicated that an erect landing pattern, characterized by less hip and knee flexion, was significantly associated with an

  14. Pseudoaneurysm of the Profunda Femoris Artery following Blunt Trauma Treated by Endovascular Coil Embolization: Review of Two Cases and Relevant Literature

    PubMed Central

    McNerney, Patrick; Kiproff, Paul

    2017-01-01

    Profunda femoris artery (PFA) pseudoaneurysm after blunt trauma without associated femur fracture is a rare occurrence. Most of the reported cases of PFA pseudoaneurysm in the English literature developed after penetrating trauma, surgical procedures, and femur fractures. We present two such cases following blunt trauma and without any associated long bone injury. After initial imaging failed to show any long bone fracture, CT angiography confirmed pseudoaneurysm of the branch of the PFA. Both patients were then treated with emergent coil embolization of the bleeding vessel. Pseudoaneurysms typically present late and signs of persistent hip pain, thigh swelling, presence of a pulsatile mass, and even unexplained anemia all may suggest the diagnosis. Recognition of PFA pseudoaneurysm requires high index of suspicion and is often difficult to diagnose clinically because of its location. PMID:28246563

  15. Influence of bicycle seat tube angle and hand position on lower extremity kinematics and neuromuscular control: implications for triathlon running performance.

    PubMed

    Silder, Amy; Gleason, Kyle; Thelen, Darryl G

    2011-11-01

    We investigated how varying seat tube angle (STA) and hand position affect muscle kinematics and activation patterns during cycling in order to better understand how triathlon-specific bike geometries might mitigate the biomechanical challenges associated with the bike-to-run transition. Whole body motion and lower extremity muscle activities were recorded from 14 triathletes during a series of cycling and treadmill running trials. A total of nine cycling trials were conducted in three hand positions (aero, drops, hoods) and at three STAs (73°, 76°, 79°). Participants also ran on a treadmill at 80, 90, and 100% of their 10-km triathlon race pace. Compared with cycling, running necessitated significantly longer peak musculotendon lengths from the uniarticular hip flexors, knee extensors, ankle plantar flexors and the biarticular hamstrings, rectus femoris, and gastrocnemius muscles. Running also involved significantly longer periods of active muscle lengthening from the quadriceps and ankle plantar flexors. During cycling, increasing the STA alone had no affect on muscle kinematics but did induce significantly greater rectus femoris activity during the upstroke of the crank cycle. Increasing hip extension by varying the hand position induced an increase in hamstring muscle activity, and moved the operating lengths of the uniarticular hip flexor and extensor muscles slightly closer to those seen during running. These combined changes in muscle kinematics and coordination could potentially contribute to the improved running performances that have been previously observed immediately after cycling on a triathlon-specific bicycle.

  16. The effect of neuromuscular electrical stimulation on quadriceps strength and knee function in professional soccer players: return to sport after ACL reconstruction.

    PubMed

    Taradaj, J; Halski, T; Kucharzewski, M; Walewicz, K; Smykla, A; Ozon, M; Slupska, L; Dymarek, R; Ptaszkowski, K; Rajfur, J; Pasternok, M

    2013-01-01

    The aim of this study was to assess the clinical efficacy and safety of NMES program applied in male soccer players (after ACL reconstruction) on the quadriceps muscle. The 80 participants (NMES = 40, control = 40) received an exercise program, including three sessions weekly. The individuals in NMES group additionally received neuromuscular electrical stimulation procedures on both right and left quadriceps (biphasic symmetric rectangular pulses, frequency of impulses: 2500 Hz, and train of pulses frequency: 50 Hz) three times daily (3 hours of break between treatments), 3 days a week, for one month. The tensometry, muscle circumference, and goniometry pendulum test (follow-up after 1 and 3 months) were applied. The results of this study show that NMES (in presented parameters in experiment) is useful for strengthening the quadriceps muscle in soccer athletes. There is an evidence of the benefit of the NMES in restoring quadriceps muscle mass and strength of soccer players. In our study the neuromuscular electrical stimulation appeared to be safe for biomechanics of knee joint. The pathological changes in knee function were not observed. This trial is registered with Australian and New Zealand Clinical Trials Registry ACTRN12613001168741.

  17. The Effect of NeuroMuscular Electrical Stimulation on Quadriceps Strength and Knee Function in Professional Soccer Players: Return to Sport after ACL Reconstruction

    PubMed Central

    Taradaj, J.; Halski, T.; Kucharzewski, M.; Walewicz, K.; Smykla, A.; Ozon, M.; Slupska, L.; Dymarek, R.; Ptaszkowski, K.; Rajfur, J.; Pasternok, M.

    2013-01-01

    The aim of this study was to assess the clinical efficacy and safety of NMES program applied in male soccer players (after ACL reconstruction) on the quadriceps muscle. The 80 participants (NMES = 40, control = 40) received an exercise program, including three sessions weekly. The individuals in NMES group additionally received neuromuscular electrical stimulation procedures on both right and left quadriceps (biphasic symmetric rectangular pulses, frequency of impulses: 2500 Hz, and train of pulses frequency: 50 Hz) three times daily (3 hours of break between treatments), 3 days a week, for one month. The tensometry, muscle circumference, and goniometry pendulum test (follow-up after 1 and 3 months) were applied. The results of this study show that NMES (in presented parameters in experiment) is useful for strengthening the quadriceps muscle in soccer athletes. There is an evidence of the benefit of the NMES in restoring quadriceps muscle mass and strength of soccer players. In our study the neuromuscular electrical stimulation appeared to be safe for biomechanics of knee joint. The pathological changes in knee function were not observed. This trial is registered with Australian and New Zealand Clinical Trials Registry ACTRN12613001168741. PMID:24381943

  18. Reconstruction of medial patellofemoral ligament using quadriceps tendon combined with reconstruction of medial patellotibial ligament using patellar tendon: initial experience☆

    PubMed Central

    Hinckel, Betina Bremer; Gobbi, Riccardo Gomes; Bonadio, Marcelo Batista; Demange, Marco Kawamura; Pécora, José Ricardo; Camanho, Gilberto Luis

    2016-01-01

    Objective To describe a surgical technique for anatomical reconstruction of the medial patellofemoral ligament using the quadriceps tendon, combined with reconstruction of the medial patellotibial ligament using the patellar tendon; and to present the initial results from a case series. Method The proposed technique was used on a series of cases of patients with diagnoses of patellofemoral instability and indications for surgical treatment, who were attended by the Knee Group of HC-IOT, University of São Paulo. The following were evaluated before and after the operation: range of motion (ROM), apprehension test, lateral translation test, patellar inclination test, inverted J sign, subluxation upon extension, pain from compression of the patella and pain from contraction of the quadriceps. After the operation, the patients were asked whether any new episode of dislocation had occurred, what their degree of satisfaction with the surgery was (on a scale from 0 to 10) and whether they would be prepared to go through this operation again. Results Seven knees were operated, in seven patients, with a mean follow-up of 5.46 months (±2.07). Four patients who presented apprehension before the operation did not show this after the operation. The lateral translation test became normal for all the patients, while the patellar inclination test remained positive for two patients. The patients with an inverted J sign continued to be positive for this sign. Five patients were positive for subluxation upon extension before the operation, but all patients were negative for this after the operation. None of the patients presented any new episode of dislocation of the patella. All of them stated that they were satisfied: five gave a satisfaction score of 9 and two, a score of 10. All of them said that they would undergo the operation again. Only one patient presented a postoperative complication: dehiscence of the wound. Conclusion Reconstruction of the medial patellofemoral ligament

  19. EXERCISES THAT FACILITATE OPTIMAL HAMSTRING AND QUADRICEPS CO-ACTIVATION TO HELP DECREASE ACL INJURY RISK IN HEALTHY FEMALES: A SYSTEMATIC REVIEW OF THE LITERATURE.

    PubMed Central

    Dedinsky, Rachel; Baker, Lindsey; Imbus, Samuel; Bowman, Melissa

    2017-01-01

    Background Anterior cruciate ligament (ACL) injury is common among females due to many anatomic, hormonal, and neuromuscular risk factors. One modifiable risk factor that places females at increased risk of ACL injury is a poor hamstrings: quadriceps (H:Q) co-activation ratio, which should be 0.6 or greater in order to decrease the stress placed on the ACL. Exercises that produce more quadriceps dominant muscle activation can add to the tension placed upon the ACL, potentially increasing the risk of ACL injury. Hypothesis/Purpose The purpose of this systematic review was to compare quadriceps and hamstring muscle activation during common closed kinetic chain therapeutic exercises in healthy female knees to determine what exercises are able to produce adequate H:Q co-activation ratios. Study Design Systematic Review Methods Multiple online databases were systematically searched and screened for inclusion. Eight articles were identified for inclusion. Data on mean electromyography (EMG) activation of both quadriceps and hamstring muscles, % maximal voluntary isometric contraction (MVIC), and H:Q co-activation ratios were extracted from the studies. Quality assessment was performed on all included studies. Results Exercises analyzed in the studies included variations of the double leg squat, variations of the single leg squat, lateral step-up, Fitter, Stairmaster® (Core Health and Fitness, Vancouver, WA), and slide board. All exercises, except the squat machine with posterior support at the level of the scapula and feet placed 50 cm in front of the hips, produced higher quadriceps muscle activation compared to hamstring muscle activation. Conclusion Overall, two leg squats demonstrate poor H:Q co-activation ratios. Single leg exercises, when performed between 30 and 90 degrees of knee flexion, produce adequate H:Q ratios, thereby potentially reducing the risk of tensile stress on the ACL and ACL injury. Level of Evidence 2a- Systematic Review of Cohort Studies PMID

  20. Higher Protein Intake Is Associated with Higher Lean Mass and Quadriceps Muscle Strength in Adult Men and Women12

    PubMed Central

    Sahni, Shivani; Mangano, Kelsey M; Hannan, Marian T; Kiel, Douglas P; McLean, Robert R

    2015-01-01

    Background: The impact of dietary protein intake on lower extremity lean mass and strength in community-dwelling adult Americans is not fully understood. Objectives: The objective was to determine the associations between total protein (TP), animal protein (AP), and plant protein (PP) intakes and lean mass of the legs and quadriceps muscle strength. We further examined whether the associations with quadriceps strength may be explained by lean mass of the legs. Methods: This cross-sectional study included men (n = 1166) and women (n = 1509) from the Framingham Offspring Cohort in Massachusetts. Protein intake in grams per day was measured in either 1995–1998 or 1998–2001. Leg lean mass and isometric quadriceps strength, both in kilograms, were measured in 1996–2001. Multilinear regression models estimated adjusted least squares means of each of the muscle measures by quartile categories of protein intake, adjusting for relevant confounders and covariates. Results: Mean age was 59 ± 9 y (range: 29–86 y) and TP intake was 80 ± 27 g/d in men and 76 ± 26 g/d in women. In men and women, leg lean mass was higher in participants in the highest quartiles of TP and AP intake compared with those in the lowest quartiles of intake [least squares means (kg): TP—17.6 vs. 17.1 in men, P-trend: 0.005, and 11.7 vs. 11.4 in women, P-trend: 0.006; AP—17.6 vs. 17.1 in men, P-trend: 0.002, and 11.7 vs. 11.4 in women, P-trend: 0.003]. PP intake was not associated with lean mass in either sex. In men and women, quadriceps strength was higher in participants in the highest quartile of PP intake compared with those in the lowest quartile [least squares means (kg): 22.9 vs. 21.7 in men, P-trend: 0.01, and 19.0 vs. 18.2 in women, P-trend: 0.01]; this association was no longer significant after adjustment for fruit and vegetable intake (P-trend: 0.06 in men and 0.10 in women). Although no significant association was observed for AP intake in either sex, nonsignificant protective

  1. Effect of triceps surae and quadriceps muscle fatigue on the mechanics of landing in stepping down in ongoing gait.

    PubMed

    Barbieri, F A; Gobbi, L T B; Lee, Y J; Pijnappels, M; van Dieën, J H

    2014-01-01

    The aim of this study was to evaluate the effects of muscle fatigue of triceps surae and quadriceps muscles in stepping down in ongoing gait. We expected that the subjects would compensate for muscle fatigue to prevent potential loss of balance in stepping down. A total of 10 young participants walked over a walkway at a self-selected velocity to step down a height difference of 10-cm halfway. Five trials were performed before and after a muscle fatigue protocol. Participants performed two fatigue protocols: one for ankle muscle fatigue and another for knee muscle fatigue. Kinematics of and ground reaction forces on the leading leg were recorded. Fatigue did not cause a change in the frequency of heel or toe landing. Our results indicate that in stepping down fatigue effects are compensated by redistributing work to unfatigued muscle groups and by gait changes aimed at enhancing balance control, which was however only partially successful.

  2. Extended healing validation of an artificial tendon to connect the quadriceps muscle to the Tibia: 180-day study.

    PubMed

    Melvin, Alan J; Litsky, Alan S; Mayerson, Joel L; Stringer, Keith; Juncosa-Melvin, Natalia

    2012-07-01

    Whenever a tendon or its bone insertion is disrupted or removed, existing surgical techniques provide a temporary connection or scaffolding to promote healing, but the interface of living to non-living materials soon breaks down under the stress of these applications, if it must bear the load more than acutely. Patients are thus disabled whose prostheses, defect size, or mere anatomy limit the availability or outcomes of such treatments. Our group developed the OrthoCoupler™ device to join skeletal muscle to prosthetic or natural structures without this interface breakdown. In this study, the goat knee extensor mechanism (quadriceps tendon, patella, and patellar tendon) was removed from the right hind limb in 16 goats. The device connected the quadriceps muscle to a stainless steel bone plate on the tibia. Mechanical testing and histology specimens were collected from each operated leg and contralateral unoperated control legs at 180 days. Maximum forces in the operated leg (vs. unoperated) were 1,400 ± 93 N (vs. 1,179 ± 61 N), linear stiffnesses were 33 ± 3 N/mm (vs. 37 ± 4 N/mm), and elongations at failure were 92.1 ± 5.3 mm (vs. 68.4 ± 3.8 mm; mean ± SEM). Higher maximum forces (p = 0.02) and elongations at failure (p=0.008) of legs with the device versus unoperated controls were significant; linear stiffnesses were not (p=0.3). We believe this technology will yield improved procedures for clinical challenges in orthopedic oncology, revision arthroplasty, tendon transfer, and tendon injury reconstruction.

  3. Muscle activation and blood flow do not explain the muscle length-dependent variation in quadriceps isometric endurance.

    PubMed

    Kooistra, R D; de Ruiter, C J; de Haan, A

    2005-03-01

    We investigated the role of central activation in muscle length-dependent endurance. Central activation ratio (CAR) and rectified surface electromyogram (EMG) were studied during fatigue of isometric contractions of the knee extensors at 30 and 90 degrees knee angles (full extension = 0 degree). Subjects (n = 8) were tested on a custom-built ergometer. Maximal voluntary isometric knee extension with supramaximal superimposed burst stimulation (three 100-mus pulses; 300 Hz) was performed to assess CAR and maximal torque capacity (MTC). Surface EMG signals were obtained from vastus lateralis and rectus femoris muscles. At each angle, intermittent (15 s on 6 s off) isometric exercise at 50% MTC with superimposed stimulation was performed to exhaustion. During the fatigue task, a sphygmomanometer cuff around the upper thigh ensured full occlusion (400 mmHg) of the blood supply to the knee extensors. At least 2 days separated fatigue tests. MTC was not different between knee angles (30 degrees : 229.6 +/- 39.3 N.m vs. 90 degrees: 215.7 +/- 13.2 N.m). Endurance times, however, were significantly longer (P < 0.05) at 30 vs. 90 degrees (87.8 +/- 18.7 vs. 54.9 +/- 12.1 s, respectively) despite the CAR not differing between angles at torque failure (30 degrees: 0.95 +/- 0.05 vs. 90 degrees: 0.96 +/- 0.03) and full occlusion of blood supply to the knee extensors. Furthermore, rectified surface EMG values of the vastus lateralis (normalized to prefatigue maximum) were also similar at torque failure (30 degrees : 56.5 +/- 12.5% vs. 90 degrees : 58.3 +/- 15.2%), whereas rectus femoris EMG activity was lower at 30 degrees (44.3 +/- 12.4%) vs. 90 degrees (69.5 +/- 25.3%). We conclude that differences in endurance at different knee angles do not find their origin in differences in central activation and blood flow but may be a consequence of muscle length-related differences in metabolic cost.

  4. Changes in the amounts of water-soluble umami-related substances in porcine longissimus and biceps femoris muscles during moist heat cooking.

    PubMed

    Sasaki, Keisuke; Motoyama, Michiyo; Mitsumoto, Mitsuru

    2007-10-01

    Time course changes in amounts of glutamic acid, total free amino acid, inosine monophosphate (IMP), and 2%-trichloroacetic acid-soluble oligopeptides in whole, muscle only, and cooking juice during wet-heat cooking in pork longissimus and biceps femoris muscles were investigated because the movements of umami-relevant substances during cooking treatment had not previously been clarified in detail. The amounts of glutamic acid, total free amino acid, and IMP significantly (P<.05) decreased and increased in muscle and cooking juice during 180min of cooking, respectively. The whole amounts of glutamic acid and total free amino acid remained unchanged during cooking treatment. The whole amount of IMP, however, increased significantly at 10min of cooking (P<.05) and was maintained after the 10-min period. The extramuscular oligopeptides amount increased significantly in response to the cooking treatment (P<.05). The intramuscular amount of oligopeptides decreased at 30min of cooking but increased significantly (P<.05) after 60min. The whole meat oligopeptides amount increased significantly during a 180-min cooking treatment (P<.05). These results indicate that glutamate, total free amino acid, and IMP were released from the muscle during cooking, and that IMP levels increased in the initial phase of cooking. In addition, oligopeptides increased during wet-heat cooking of pork muscles.

  5. A Comparison of Gluteus Maximus, Biceps Femoris, and Vastus Lateralis Electromyography Amplitude in the Parallel, Full, and Front Squat Variations in Resistance-Trained Females.

    PubMed

    Contreras, Bret; Vigotsky, Andrew D; Schoenfeld, Brad J; Beardsley, Chris; Cronin, John

    2016-02-01

    Front, full, and parallel squats are some of the most popular squat variations. The purpose of this investigation was to compare mean and peak electromyography (EMG) amplitude of the upper gluteus maximus, lower gluteus maximus, biceps femoris, and vastus lateralis of front, full, and parallel squats. Thirteen healthy women (age = 28.9 ± 5.1 y; height = 164 ± 6.3 cm; body mass = 58.2 ± 6.4 kg) performed 10 repetitions of their estimated 10-repetition maximum of each respective variation. There were no statistical (P ≤ .05) differences between full, front, and parallel squats in any of the tested muscles. Given these findings, it can be concluded that the front, full, or parallel squat can be performed for similar EMG amplitudes. However, given the results of previous research, it is recommended that individuals use a full range of motion when squatting, assuming full range can be safely achieved, to promote more favorable training adaptations. Furthermore, despite requiring lighter loads, the front squat may provide a similar training stimulus to the back squat.

  6. A Comparison of Gluteus Maximus, Biceps Femoris, and Vastus Lateralis Electromyography Amplitude for the Barbell, Band, and American Hip Thrust Variations.

    PubMed

    Contreras, Bret; Vigotsky, Andrew D; Schoenfeld, Brad J; Beardsley, Chris; Cronin, John

    2016-06-01

    Bridging exercise variations are well researched and commonly employed for both rehabilitation and sport performance. However, resisted bridge exercise variations have not yet been compared in a controlled experimental study. Therefore, the purpose of this study was to compare the differences in upper and lower gluteus maximus, biceps femoris, and vastus lateralis electromyography (EMG) amplitude for the barbell, band, and American hip thrust variations. Thirteen healthy female subjects (age = 28.9 y; height = 164.3 cm; body mass = 58.2 kg) familiar with the hip thrust performed 10 repetitions of their 10-repetition maximum of each variation in a counterbalanced and randomized order. The barbell hip thrust variation elicited statistically greater mean gluteus maximus EMG amplitude than the American and band hip thrusts, and statistically greater peak gluteus maximus EMG amplitude than the band hip thrust (P ≤ .05), but no other statistical differences were observed. It is recommended that resisted bridging exercise be prescribed according to the individual's preferences and desired outcomes.

  7. Bilateral Simultaneous Quadriceps Tendon Rupture in a 24-Year-Old Obese Patient: A Case Report and Review of the Literature

    PubMed Central

    Aljurayyan, Abdulaziz; Ghalimah, Bayan; Lincoln, Lawrence

    2016-01-01

    Introduction. Simultaneous bilateral quadriceps tendon ruptures (SBQTR) are uncommon knee injuries and most frequently occur in male patients, over 50 years of age. It can be associated with one or more predisposing risk factors like obesity, steroids use, and hyperparathyroidism. The main focus of this paper is to review SBQTR in obese patients. Case Report. We are reporting the youngest patient in the literature to date, a 24-year-old obese male patient, who presented to the emergency department complaining of bilateral knee pain and inability to walk after a fall during a basketball game. His clinical examination revealed the presence of a palpable suprapatellar gap and loss of knee extension bilaterally. Magnetic resonance imaging (MRI) confirmed that both of his quadriceps tendons were ruptured. A day after his diagnosis, the patient underwent successful operative repair followed by rehabilitation. At the two-year follow-up, the patient had full strength of both quadriceps muscles with no extension lag. Conclusion. The diagnosis of SBQTR can be challenging. Early diagnosis and treatment are associated with better functional outcome compared to delayed treatment. Physicians should have a high index of clinical suspicion in order not to miss such an injury and achieve favourable outcomes. PMID:27840757

  8. Do Three Different Passive Assessments of Quadriceps Spasticity Relate to the Functional Activity of Walking for Children Diagnosed with Cerebral Palsy?

    PubMed Central

    White, Hank; Uhl, Tim L.; Augsburger, Sam

    2015-01-01

    A stiff-knee gait pattern is frequently associated with several impairments including quadriceps spasticity in children diagnosed with cerebral palsy (CP). The relationship of clinical measures of quadriceps spasticity and the stiff-knee gait pattern in children diagnosed with CP has not been well established. Therefore, the purpose of this study was to determine the ability of clinical measures of quadriceps spasticity (modified Ashworth scale [MAS], Ely tests, and pendulum test) to categorize a stiff-knee gait pattern in children with CP. Children were categorized as having a stiff-knee gait pattern based on kinematic and EMG gait data. Results of a logistic regression model revealed that the only significant measure was A1 of the pendulum test. Discriminant analysis functions were used to predict group membership (stiff-knee, not stiff-knee gait pattern) for each measure. The A1 of the pendulum test demonstrated the highest classification accuracy and the highest sensitivity compared to the other measures. Therefore, a negative pendulum test (indicated by an A1 value of 45 degrees or more) is more useful for ruling out a stiff-knee gait pattern compared to the other clinical measures. PMID:26576411

  9. Reconstruction of the medial patellofemoral ligament using autologous graft from quadriceps tendon to treat recurrent patellar dislocation☆

    PubMed Central

    Calapodopulos, Constantino Jorge; Nogueira, Marcelo Corvino; Eustáquio, José Martins Juliano; Calapodopulos Júnior, Constantino Jorge; Rodrigues, Oreston Alves

    2016-01-01

    Objective The objective of this study was to evaluate the efficacy of the surgical technique using the quadriceps tendon as a graft in static reconstruction of the medial patellofemoral ligament. Methods This was a prospective case series study in which the participants were 22 patients with a diagnosis of recurrent patellar dislocation without any other anatomical alterations that required surgical treatment. The functional results from the technique were evaluated using clinical data and the Lysholm questionnaire, one year after the operation. Results It was observed that the patients were predominantly female (86%) and under 21 years of age (73%), just like in the literature. At the first annual return after the surgery, there was no significant pain on medium efforts, no loss of range of motion and a positive apprehension test. According to the questionnaire used, the results were graded as good. The patients who reported having severe pain on greater effort were involved in employment-related legal disputes. Conclusion This technique showed low morbidity and good functional results over the short term. PMID:27069888

  10. Anthropometric and quantitative EMG status of femoral quadriceps before and after conventional kinesitherapy with and without magnetotherapy.

    PubMed

    Graberski Matasović, M; Matasović, T; Markovac, Z

    1997-06-01

    The frequency of femoral quadriceps muscle hypotrophy has become a significant therapeutic problem. Efforts are being made to improve the standard scheme of kinesitherapeutic treatment by using additional more effective therapeutic methods. Beside kinesitherapy, the authors have used magnetotherapy in 30 of the 60 patients. The total of 60 patients, both sexes, similar age groups and intensity of hypotrophy, were included in the study. They were divided into groups A and B, the experimental and the control one (30 patients each). The treatment was scheduled for the usual 5-6 weeks. Electromyographic quantitative analysis was used to check-up the treatment results achieved after 5 and 6 weeks of treatment period. Analysis of results has confirmed the assumption that magnetotherapy may yield better and faster treatment results, disappearance of pain and decreased risk of complications. The same results were obtained in the experimental group, only one week earlier than in the control group. The EMG quantitative analysis has not proved sufficiently reliable and objective method in the assessment of real condition of the muscle and effects of treatment.

  11. Hereditary inclusion-body myopathy with sparing of the quadriceps: the many tiles of an incomplete puzzle.

    PubMed

    Broccolini, A; Gidaro, T; Morosetti, R; Sancricca, C; Mirabella, M

    2011-10-01

    The hereditary inclusion-body myopathies encompass several syndromes with autosomal recessive or dominant inheritance. Despite a different clinical presentation they all have a progressive course leading to severe disability and share similar pathologic findings at the muscle biopsy. Quadriceps-sparing autosomal recessive hereditary inclusion-body myopathy (h-IBM) is the commonest form and is tied to mutations of the UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE) that codes for a rate-limiting enzyme in the sialic acid biosynthetic pathway. Despite the identification of the causative gene defect, it has not been clarified how mutations of the GNE gene impair muscle homeostasis. Although several lines of evidence argue in favor of an abnormal sialylation of muscle glycoproteins playing a key role in h-IBM pathogenesis, others studies have demonstrated new functions of the GNE gene, outside the sialic acid biosynthetic pathway, that may also be relevant. This review illustrates the clinical and pathologic characteristics of h-IBM and the main clues available to date concerning the possible pathogenic mechanisms of this disorder. Understanding the molecular mechanism underlying h-IBM pathology is a fundamental requisite to plan a future attempt to therapy.

  12. Effects of live weight at slaughter on fatty acid composition of Longissimus dorsi and Biceps femoris muscles of indigenous Lori goat.

    PubMed

    Kiani, Ali; Fallah, Rozbeh

    2016-01-01

    This study aimed to determine fatty acid (FA) composition of Longissimus dorsi (LD) and Biceps femoris (BF) muscles of an Iranian indigenous goat (Lori goat) at two live weights at slaughter (LWS). Twenty male Lori goats (5 to 8 months) raised in nomadic system were slaughtered either at LWS less than 20 kg (light) or LWS more than 30 kg (heavy). Carcass dressing and FA composition of intramuscular fat of LD and BF muscles as well as cholesterol content of LD muscle were determined. Heavy goats had higher dressing percentage than light ones (42.7vs.39.3%, P < 0.01). The predominant n-6 FA were C18:2, and C20:4 while C22:5, C20:5, C18:3, C20:3, and C22:6 were the n-3 FA detected. Polyunsaturated and saturated FA contributed 22% and 36% of the total FA in both muscles, respectively. Palmitic acid (C16:0) of LD was higher in heavy compared to the light goats (P < 0.05). BF muscle had higher α-linolenic acid (18:3 n-3) as percentage than LD muscle (P < 0.05). The ratio of n-6/n-3 FA and polyunsaturated/saturated FA were 3.8 and 0.6, respectively. Cholesterol content of LD muscle of light and heavy goats were 71.2 ± 16 and 59.5 ± 14 mg per 100 g fresh meat respectively. In conclusion, desirable PUFA/SFA (0.6) and n-3/n-6 ratio (3.8) found in indigenous Lori goat propose healthy source of lean meat for the consumers.

  13. Knee angle-dependent oxygen consumption of human quadriceps muscles during maximal voluntary and electrically evoked contractions.

    PubMed

    Kooistra, R D; de Ruiter, C J; de Haan, A

    2008-01-01

    Fatigability and muscle oxygen consumption (mVO(2)) during sustained voluntary isometric knee extensions are less at extended (30 degrees knee angle; 0 degrees , full extension) versus flexed knee angles (90 degrees). This lower energy consumption may partially result from lower neural activation at extended knee angles. We hypothesized a smaller difference in mVO(2) between extended and flexed knee angles during electrical stimulation, which guaranteed maximal activation, than during maximal voluntary contractions (MVC). In eight healthy young males, MVC extension torque was obtained at 30 degrees, 60 degrees and 90 degrees knee angles. mVO(2) of the rectus femoris (RF), vastus lateralis (VL) and medialis muscle was measured using near-infrared spectroscopy during tetanic (10 s) and maximal voluntary (15 s) contractions (MVC(15)). For electrically induced contractions, steady state mVO(2) was reached at similar (P > 0.05) times after torque onset (4.6 +/- 0.7 s) at all knee angles. In contrast, during MVC(15) at 30 degrees mVO(2) was reached at 7.1 +/- 1.1 s, significantly later compared to 60 degrees and 90 degrees knee angles. The knee angle dependent differences in mVO(2) were not lower in electrically induced contractions (as hypothesised) but were similar as in voluntary contractions. Normalized mVO(2) at 30 degrees (percentage 90 degrees knee angle) was 79.0 +/- 9.4% (across muscles) for electrically induced and 79.5 +/- 7.6% (across muscles) for voluntary contractions (P < 0.05). We conclude that the slower onset of mVO(2) during voluntary effort at 30 degrees may have been due to a lower maximal activation. However, because steady state mVO(2) both during electrically induced and voluntary contractions was approximately 20% less at extended versus flexed knee angles, the causes for the lower mVO(2) must reside within the muscle itself.

  14. Evidence of O2 supply-dependent VO2 max in the exercise-trained human quadriceps.

    PubMed

    Richardson, R S; Grassi, B; Gavin, T P; Haseler, L J; Tagore, K; Roca, J; Wagner, P D

    1999-03-01

    Maximal O2 delivery and O2 uptake (VO2) per 100 g of active muscle mass are far greater during knee extensor (KE) than during cycle exercise: 73 and 60 ml. min-1. 100 g-1 (2.4 kg of muscle) (R. S. Richardson, D. R. Knight, D. C. Poole, S. S. Kurdak, M. C. Hogan, B. Grassi, and P. D. Wagner. Am. J. Physiol. 268 (Heart Circ. Physiol. 37): H1453-H1461, 1995) and 28 and 25 ml. min-1. 100 g-1 (7.5 kg of muscle) (D. R. Knight, W. Schaffartzik, H. J. Guy, R. Predilleto, M. C. Hogan, and P. D. Wagner. J. Appl. Physiol. 75: 2586-2593, 1993), respectively. Although this is evidence of muscle O2 supply dependence in itself, it raises the following question: With such high O2 delivery in KE, are the quadriceps still O2 supply dependent at maximal exercise? To answer this question, seven trained subjects performed maximum KE exercise in hypoxia [0.12 inspired O2 fraction (FIO2)], normoxia (0.21 FIO2), and hyperoxia (1.0 FIO2) in a balanced order. The protocol (after warm-up) was a square wave to a previously determined maximum work rate followed by incremental stages to ensure that a true maximum was achieved under each condition. Direct measures of arterial and venous blood O2 concentration in combination with a thermodilution blood flow technique allowed the determination of O2 delivery and muscle VO2. Maximal O2 delivery increased with inspired O2: 1.3 +/- 0.1, 1.6 +/- 0.2, and 1.9 +/- 0.2 l/min at 0.12, 0.21, and 1.0 FIO2, respectively (P < 0.05). Maximal work rate was affected by variations in inspired O2 (-25 and +14% at 0.12 and 1.0 FIO2, respectively, compared with normoxia, P < 0.05) as was maximal VO2 (VO2 max): 1.04 +/- 0.13, 1. 24 +/- 0.16, and 1.45 +/- 0.19 l/min at 0.12, 0.21, and 1.0 FIO2, respectively (P < 0.05). Calculated mean capillary PO2 also varied with FIO2 (28.3 +/- 1.0, 34.8 +/- 2.0, and 40.7 +/- 1.9 Torr at 0.12, 0.21, and 1.0 FIO2, respectively, P < 0.05) and was proportionally related to changes in VO2 max, supporting our previous finding that a

  15. Torque decrease during submaximal evoked contractions of the quadriceps muscle is linked not only to muscle fatigue.

    PubMed

    Matkowski, Boris; Lepers, Romuald; Martin, Alain

    2015-05-01

    The aim of this study was to analyze the neuromuscular mechanisms involved in the torque decrease induced by submaximal electromyostimulation (EMS) of the quadriceps muscle. It was hypothesized that torque decrease after EMS would reflect the fatigability of the activated motor units (MUs), but also a reduction in the number of MUs recruited as a result of changes in axonal excitability threshold. Two experiments were performed on 20 men to analyze 1) the supramaximal twitch superimposed and evoked at rest during EMS (Experiment 1, n = 9) and 2) the twitch response and torque-frequency relation of the MUs activated by EMS (Experiment 2, n = 11). Torque loss was assessed by 15 EMS-evoked contractions (50 Hz; 6 s on/6 s off), elicited at a constant intensity that evoked 20% of the maximal voluntary contraction (MVC) torque. The same stimulation intensity delivered over the muscles was used to induce the torque-frequency relation and the single electrical pulse evoked after each EMS contraction (Experiment 2). In Experiment 1, supramaximal twitch was induced by femoral nerve stimulation. Torque decreased by ~60% during EMS-evoked contractions and by only ~18% during MVCs. This was accompanied by a rightward shift of the torque-frequency relation of MUs activated and an increase of the ratio between the superimposed and posttetanic maximal twitch evoked during EMS contraction. These findings suggest that the torque decrease observed during submaximal EMS-evoked contractions involved muscular mechanisms but also a reduction in the number of MUs recruited due to changes in axonal excitability.

  16. RECONSTRUCTION OF THE ANTERIOR CRUCIATE LIGAMENT WITH THE CENTRAL THIRD OF THE QUADRICEPS MUSCLE TENDON: ANALYSIS OF 10-YEAR RESULTS

    PubMed Central

    Guimarães, Marcus Valladares; Junior, Lúcio Honório de Carvalho; Terra, Dalton Lopes

    2015-01-01

    Objective: Assess clinical results using two different protocols, 10 years after ACL reconstruction surgery with the central third of quadriceps muscle tendon (QT). Method: Between November /1997 and April/1998, 25 patients were submitted to 25 ACL reconstructions with QT by transtibial technique. The bone portion of the graft was fixated on femoral tunnel with interference screw and the tendinous portion of tibial tunnel with screw with washer. Two patients injured the new when playing soccer. Six patients were not available for follow-up (24%). Seventeen patients were evaluated, 15 men and two women, with mean age at surgery time of 28.53 ± 6.64 years. All patients were examined at six months, one year, and ten years after surgery. Clinical evaluation was made by the Lysholm scale, and the knee evaluation, with the Hospital for Special Surgery scale. Results: The patients had their injuries operated after 9.87 ± 14.42 months of the accident. According to Lysholm scale, the results at the end of the first year were 98.71 ± 2.47 and, after 10 years, 97.35 ± 3.12. Using the Hospital for Special Surgery scale, the mean score was 95.07 ± 5.23 in one year, and 94.87 ± 4.16 in 10 years. All patients returned to their professional activities with the same previous status. Fifteen (88.24%) patients were able to return to their sports activities, one by modifying the practice, while another one switched to another sport. No patient complained of pain on the donor area in the medium and long term. The sports return rate was excellent, and no changes were found on the femoropatellar joint. PMID:27022511

  17. RAPID KNEE-EXTENSIONS TO INCREASE QUADRICEPS MUSCLE ACTIVITY IN PATIENTS WITH TOTAL KNEE ARTHROPLASTY: A RANDOMIZED CROSS-OVER STUDY

    PubMed Central

    Wilquin, Lousia; Jakobsen, Thomas Linding; Holsgaard-Larsen, Anders; Bandholm, Thomas

    2017-01-01

    Background Inhibition of the quadriceps muscle and reduced knee-extension strength is common shortly following total knee arthroplasty (weeks to months), due to reduced voluntary activation of the quadriceps muscle. In healthy subjects, strength training with heavy loads is known to increase agonist muscle activity, especially if the exercise is conducted using rapid muscle contractions. Purpose The purpose of this study was to examine if patients with total knee arthroplasty could perform rapid knee-extensions using a 10 RM load four to eight weeks after surgery, and the degree to which rapid knee-extensions were associated with greater voluntary quadriceps muscle activity during an experimental strength training session, compared to that elicited using slow knee-extensions. Study Design A randomized cross-over study. Methods Twenty-four patients (age 66.5) 4-8 weeks post total knee arthroplasty randomly performed one set of five rapid, and one set of five slow knee-extensions with the operated leg, using a load of their 10 repetition maximum, while surface electromyography recordings were obtained from the vastus medialis and lateralis of the quadriceps muscle. Results Data from 23 of the 24 included patients were analyzed. Muscle activity was significantly higher during rapid knee-extensions (120.2% [10th-90th percentile: 98.3-149.1]) compared to slow knee-extensions (106.0% [88.8-140.8]) for the vastus lateralis (p<0.01), but not for the vastus medialis (120.8% [90.4-134.0]) and (121.8% [93.0-133.0]) (p = 0.17), respectively. Slow and rapid knee-extensions were performed at a median angular velocity of 19.7 degrees/sec (13.7-24.4) and 51.4 degrees/sec (28.9-63.1), respectively Conclusion Four to eight weeks after their total knee arthroplasty, the patients in the present study were able to conduct rapid knee-extensions according to the experimental protocol with an approximately doubled angular velocity compared to slow knee-extensions. This was associated with

  18. Effect of 3 Different Applications of Kinesio Taping Denko® on Electromyographic Activity: Inhibition or Facilitation of the Quadriceps of Males During Squat Exercise.

    PubMed

    Serrão, Júlio C; Mezêncio, Bruno; Claudino, João G; Soncin, Rafael; Miyashiro, Pedro L Sampaio; Sousa, Eric P; Borges, Eduardo; Zanetti, Vinícius; Phillip, Igor; Mochizuki, Luiz; Amadio, Alberto C

    2016-09-01

    Kinesio taping consists of a technique which uses the application of an elastic adhesive tape. It has become a widely used rehabilitation modality for the prevention and treatment of musculoskeletal disorders. The objective of this study was to verify the effect of the application of Kinesio Taping Denko(®) in three conditions (facilitation, inhibition, and placebo) on the electromyographic activity of the quadriceps and hamstrings muscles on facilitating or inhibiting the muscle function and on the perceived exertion during the barbell back squat exercise in healthy male subjects.

  19. Examinations of factors influencing toe grip strength

    PubMed Central

    Soma, Masayuki; Murata, Shin; Kai, Yoshihiro; Nakae, Hideyuki; Satou, Yousuke; Murata, Jun; Miyazaki, Junya

    2016-01-01

    [Purpose] This study examined the relationship between toe grip strength and its associated factors by focusing on factors that were suggested to have a relationship with toe grip strength in previous studies, aiming to clarify the factors influencing the toe grip strength of healthy women. [Subjects and Methods] Twelve healthy young women were selected for this study. Their toe grip strength, angular changes in their ankle joint during toe grip, maximum voluntary contraction activities of the rectus femoris, biceps femoris, and tibialis anterior muscles, and the medial head of the gastrocnemius muscles were measured using electromyography. Their toe curl ability, foot-arch height ratio, and weight were also measured. [Results] Multiple regression analysis demonstrated that the predictors of toe grip strength in the resulting model were foot-arch height ratio and the percentage of integrated electromyography (%IEMG) of the tibialis anterior muscle, as the dependent variables. This reveals that women whose tibialis anterior muscle %IEMG values and foot-arch height ratio are high have greater %IEMG values have greater toe grip strength. [Conclusion] These findings suggest a significant relationship between foot-arch height ratio and toe grip strength, with a reciprocal interaction. These findings further indicate that the risk of falls by the elderly could be decreased if toe grip strength were enhanced, by increasing the height of a low foot-arch with the help of an inserted insole. PMID:27942134

  20. Examinations of factors influencing toe grip strength.

    PubMed

    Soma, Masayuki; Murata, Shin; Kai, Yoshihiro; Nakae, Hideyuki; Satou, Yousuke; Murata, Jun; Miyazaki, Junya

    2016-11-01

    [Purpose] This study examined the relationship between toe grip strength and its associated factors by focusing on factors that were suggested to have a relationship with toe grip strength in previous studies, aiming to clarify the factors influencing the toe grip strength of healthy women. [Subjects and Methods] Twelve healthy young women were selected for this study. Their toe grip strength, angular changes in their ankle joint during toe grip, maximum voluntary contraction activities of the rectus femoris, biceps femoris, and tibialis anterior muscles, and the medial head of the gastrocnemius muscles were measured using electromyography. Their toe curl ability, foot-arch height ratio, and weight were also measured. [Results] Multiple regression analysis demonstrated that the predictors of toe grip strength in the resulting model were foot-arch height ratio and the percentage of integrated electromyography (%IEMG) of the tibialis anterior muscle, as the dependent variables. This reveals that women whose tibialis anterior muscle %IEMG values and foot-arch height ratio are high have greater %IEMG values have greater toe grip strength. [Conclusion] These findings suggest a significant relationship between foot-arch height ratio and toe grip strength, with a reciprocal interaction. These findings further indicate that the risk of falls by the elderly could be decreased if toe grip strength were enhanced, by increasing the height of a low foot-arch with the help of an inserted insole.

  1. Early Patient Outcomes After Primary Total Knee Arthroplasty with Quadriceps-Sparing Subvastus and Medial Parapatellar Techniques

    PubMed Central

    Tomek, Ivan M.; Kantor, Stephen R.; Cori, LuAnne A.; Scoville, Jennifer M.; Grove, Margaret R.; Morgan, Tamara S.; Swarup, Ishaan; Moschetti, Wayne E.; Spratt, Kevin F.

    2014-01-01

    Background: Techniques that reduce injury to the knee extensor mechanism may cause less pain and allow faster recovery of knee function after primary total knee arthroplasty. A quadriceps-sparing (QS) subvastus technique of total knee arthroplasty was compared with medial parapatellar arthrotomy (MPPA) to determine which surgical technique led to better patient-reported function and less postoperative pain and opioid utilization. Methods: In this prospective, double-blind study, 129 patients undergoing total knee arthroplasty were randomized to the QS or the MPPA group after skin incision. All surgical procedures utilized minimally invasive surgery principles and standardized anesthesia, implants, analgesia, and rehabilitation. The Knee Society Score (KSS) was obtained at baseline and one and three months after surgery. Weekly telephone interviews were used to collect patient-reported outcomes including ambulatory device use, the UCLA (University of California Los Angeles) activity score, performance of daily living activities, and opioid utilization. Results: No differences between groups were seen in opioid utilization, either during the acute hospitalization or in the eight weeks after surgery. The QS group reported significantly less pain at rest on postoperative day one and with activity on day three (p = 0.04 for each). Compared with baseline, both groups showed significant improvements in the KSS at one month (MPPA, p = 0.0278; QS, p = 0.0021) and three months (p < 0.0001 for each) as well as week-to-week gains in walking independence through five weeks after surgery. Independence from ambulatory devices outside the home lagged behind independence indoors by about two weeks in both groups. Conclusions: When primary total knee arthroplasty was performed with contemporary minimally invasive surgery principles and standardized implants, anesthesia, and postoperative pathways, the QS technique yielded no significant early functional advantages or differences in

  2. Consumption of oxygen and blood flow during exercise and recovery phase evaluated by near-infrared spectroscopy and its relationship to skin forehead, quadriceps, tympanic, and rectal temperatures

    NASA Astrophysics Data System (ADS)

    Verdaguer-Codina, Joan; Pujol, P.; Drobnic, F.; Galilea, P.; Riera, J.; Pons, V.; Banquells, M.; Ruiz, O.

    1995-12-01

    The availability of oxygen in the human vastus medialis muscle and the tympanic, skin forehead, quadriceps, and rectal temperatures has been investigated during exercise test and post-exercise with non-invasive near-infrared spectroscopy, infrared thermometer, and an array of four thermistors, respectively. During exercise time rectal temperature was not recorded, before exercise basal values were obtained, and after exercise all the data for two hours were recorded. The signals from near-infrared spectroscopy have been studied by analogy to forced vibration and viscously damped free vibration. Other models have been used to evaluate the temperatures. The time necessary for the reoxygenation signal to cross the baseline during the post exercise period was from 30 min to over 100 min. The peak of pH values was 5 min post-exercise and to arrive at basal levels needed 25 min to more than 40 min. The peak of rectal temperature starts around 20 - 30 min post-exercise remaining 25 - 40 min at the same value, starting to slip down slowly at variable intervals of several minutes requiring over two hours to arrive at basal levels. The data obtained by near-infrared spectroscopy and skin quadriceps, rectal temperatures confirm that the oxygen consumption remains after exercise in the muscle studied.

  3. Handgrip strength, quadriceps muscle power, and optimal shortening velocity roles in maintaining functional abilities in older adults living in a long-term care home: a 1-year follow-up study

    PubMed Central

    Kozicka, Izabela; Kostka, Tomasz

    2016-01-01

    Purpose To assess the relative role of handgrip strength (HGS), quadriceps muscle power (Pmax), and optimal shortening velocity (υopt) in maintaining functional abilities (FAs) in older adults living in a long-term care home over a 1-year follow-up. Subjects and methods Forty-one inactive older institutionalized adults aged 69.8±9.0 years participated in this study. HGS, Pmax, υopt, cognitive function using the Mini-Mental State Examination, depressive symptoms using the Geriatric Depression Scale, nutritional status using the Mini Nutritional Assessment (MNA), and physical activity (PA) using the Seven-Day Physical Activity Recall Questionnaire were assessed at baseline and at 1-year follow-up. FAs were assessed with activities of daily living (ADL), instrumental ADL, and Timed Up & Go test. Results Both at baseline and at follow-up, FAs were related to age, HGS, Pmax/kg, υopt, MNA, and PA. These associations were generally similar in both sexes. As revealed in multiple regression analysis, υopt was the strongest predictor of FA, followed by Pmax/kg, PA, and MNA. FA deteriorated after 1 year as measured by ADL and Timed Up & Go test. Pmax and υopt, but not HGS, also decreased significantly after 1 year. Nevertheless, 1-year changes in FAs were not related to changes in HGS, Pmax, υopt, or PA. Conclusion The 1-year period of physical inactivity among older institutionalized adults was found to have a negative effect on their FAs, Pmax, and υopt. The present study demonstrates that Pmax and, especially, υopt correlated with FAs of older adults more than HGS, both at baseline and at follow-up. Despite this, 1-year natural fluctuations of PA, Pmax, and υopt are not significant enough to influence FAs in inactive institutionalized older adults. PMID:27307720

  4. The Effect of Warm-Up and Cool-Down Exercise on Delayed Onset Muscle Soreness in the Quadriceps Muscle: a Randomized Controlled Trial

    PubMed Central

    Olsen, Olav; Sjøhaug, Mona; van Beekvelt, Mireille; Mork, Paul Jarle

    2012-01-01

    The aim of the present study was to investigate the effect of warm-up and cool-down exercise on delayed onset of muscle soreness at the distal and central parts of rectus femoris following leg resistance exercise. Thirty-six volunteers (21 women, 15 men) were randomly assigned to the warm-up (20 min ergometer cycling prior to the resistance exercise), cool-down (20 min cycling after the resistance exercise), or control group performing resistance exercise only. The resistance exercise consisted of front lunges (10×5 repetitions/sets) with external loading of 40% (women) and 50% (men) of body mass. Primary outcomes were pressure pain threshold along rectus femoris and maximal isometric knee extension force. Data were recorded before the resistance exercise and on the two consecutive days. Pressure pain threshold at the central muscle belly was significantly reduced for the control group on both day 2 and 3 (p≤0.003) but not for the warm-up group (p≥0.21). For the cool-down group, pressure pain threshold at the central muscle belly was significantly reduced on day 2 (p≤0.005) and was also lower compared to the warm-up group (p=0.025). Force was significantly reduced on day 2 and 3 for all groups (p<0.001). This study indicates that aerobic warm-up exercise performed prior to resistance exercise may prevent muscle soreness at the central but not distal muscle regions, but it does not prevent loss of muscle force. PMID:23486850

  5. Eccentric exercise and delayed onset muscle soreness of the quadriceps induce adjustments in agonist-antagonist activity, which are dependent on the motor task.

    PubMed

    Vila-Chã, C; Hassanlouei, H; Farina, D; Falla, D

    2012-02-01

    This study investigates the effects of eccentric exercise and delayed onset muscle soreness (DOMS) of the quadriceps on agonist-antagonist activity during a range of motor tasks. Ten healthy volunteers (age, mean ± SD, 24.9 ± 3.2 years) performed maximum voluntary contractions (MVC) and explosive isometric contractions of the knee extensors followed by isometric contractions at 2.5, 5, 10, 15, 20, and 30% MVC at baseline, immediately after and 24 h after eccentric exercise of the quadriceps. During each task, force of the knee extensors and surface EMG of the vasti and hamstrings muscles were recorded concurrently. Rate of force development (RFD) was computed from the explosive isometric contraction, and the coefficient of variation of the force (CoV) signal was estimated from the submaximal contractions. Twenty-four hours after exercise, the subjects rated their perceived pain intensity as 4.1 ± 1.2 (score out of 10). The maximum RFD and MVC of the knee extensors was reduced immediately post- and 24 h after eccentric exercise compared to baseline (average across both time points: 19.1 ± 17.1% and 11.9 ± 9.8% lower, respectively, P < 0.05). The CoV for force during the submaximal contractions was greater immediately after eccentric exercise (up to 66% higher than baseline, P < 0.001) and remained higher 24 h post-exercise during the presence of DOMS (P < 0.01). For the explosive and MVC tasks, the EMG amplitude of the vasti muscles decreased immediately after exercise and was accompanied by increased antagonist EMG for the explosive contraction only. On the contrary, reduced force steadiness was accompanied by a general increase in EMG amplitude of the vasti muscles and was accompanied by increased antagonist activity, but only at higher force levels (>15% MVC). This study shows that eccentric exercise and subsequent DOMS of the quadriceps reduce the maximal force, rate of force development and force steadiness of the knee extensors, and is

  6. The influence of different footwear on 3-D kinematics and muscle activation during the barbell back squat in males.

    PubMed

    Sinclair, Jonathan; McCarthy, Derek; Bentley, Ian; Hurst, Howard Thomas; Atkins, Stephen

    2015-01-01

    The barbell back squat is commonly used by athletes participating in resistance training. The barbell squat is typically performed using standard athletic shoes, or specially designed weightlifting footwear, although there are now a large number of athletes who prefer to squat barefoot or in barefoot-inspired footwear. This study aimed to determine how these footwear influence 3-D kinematics and muscle activation potentials during the barbell back squat. Fourteen experienced male participants completed squats at 70% 1 rep max in each footwear condition. 3-D kinematics from the torso, hip, knee and ankle were measured using an eight-camera motion analysis system. In addition, electromyographical (EMG) measurements were obtained from the rectus femoris, tibialis anterior, gastrocnemius, erector spinae and biceps femoris muscles. EMG parameters and joint kinematics were compared between footwear using repeated-measures analyses of variance. Participants were also asked to subjectively rate which footwear they preferred when performing their squat lifts; this was examined a chi-squared test. The kinematic analysis indicated that, in comparison to barefoot the running shoe was associated with increased squat depth, knee flexion and rectus femoris activation. The chi-squared test was significant and showed that participants preferred to squat barefoot. This study supports anecdotal evidence of athletes who prefer to train barefoot or in barefoot-inspired footwear although no biomechanical evidence was found to support this notion.

  7. Exposure to microgravity for 30 days onboard Bion M1 caused muscle atrophy and decreased regeneration in the mouse femoral Quadriceps

    NASA Astrophysics Data System (ADS)

    Grigoryan, Eleonora; Radugina, Elena A.; Almeida, Eduardo; Blaber, Elizabeth; Poplinskaya, Valentina; Markitantova, Yulia

    Mechanical unloading of muscle during spaceflight in microgravity is known to cause muscular atrophy, changes in muscle fiber type composition, gene expression, and reductions in regenerative muscle growth. Although limited data exists for long-term effects of microgravity in human muscle, these processes have mostly been studied in rodents for short periods of time, up to two weeks of spaceflight. Here we report on how 30-day, long-term, mechanical unloading in microgravity affects mouse muscle of the femoral Quadriceps group. To conduct these studies we used muscle tissue from 6 mice from the NASA Biospecimen Sharing Program conducted in collaboration with the Institute for Biomedical Problems of the Russian Academy of Sciences, during the Russian Bion M1 biosatellite mission in 2013. Muscle morphology observed in histological sections shows signs of extensive atrophy and regenerative hypoplasia. Specifically, we observed a two-fold decrease in the number of myonuclei and low density of myofibrils, their separation and fragmentation. Despite obvious atrophy, muscle regeneration nevertheless appears to have continued after 30 days in microgravity as evidenced by thin and short newly formed muscle fibers. Many of them however showed evidence of apoptosis and degradation of synthesized fibrils, suggesting long-term unloading in microgravity affects late stages of myofiber differentiation. Ground asynchronous and vivarium control animals showed normal, well-developed tissue structure with sufficient blood and nerve supply and evidence of regenerative formation of new muscle fibers free of apoptotic nuclei. Myofiber nuclei stress responses in spaceflight animals was detected by positive nuclear immunolocalization of c-jun and c-myc proteins. Regenerative activity of satellite cells in muscle was localized with pax-7, MyoD and MCad immunostaining, and did not appear altered in microgravity. In summary, long-term spaceflight in microgravity causes significant atrophy

  8. Are there differences in performance, metabolism, and quadriceps muscle activity in black African and Caucasian athletes during brief intermittent and intense exercise?

    PubMed

    Temfemo, A; Laparadis, C; Bishop, D; Merzouk, A; Ahmaidi, S

    2007-08-01

    The purpose of the present study was to determine whether there are any differences in power output (PO) and/or quadriceps muscle (Quad) activity between black African and Caucasian football players during a force-velocity (fv) exercise test, which consisted of performing maximal 6-s sprints against an increasing load. Each subject started the test with a load of 2 kg and then recovered for 5 min before repeating the same test with a load increased by 2 kg. When the pedal frequency did not exceed 130 rev x min(-1), the load was increased by only 1 kg. Each subject attained the load corresponding to his maximal power if an additional increase in load (+1 kg) induced a power decrease. Nine black Africans (mean age 24.2 +/- 3.3 years) and nine Caucasians (24.7 +/- 4.2 years) (matched for stature and aerobic fitness) participated in the fv exercise test. During the test, PO, blood lactate, and the quadriceps electromyography (EMG) root mean square (Quad RMS) were assessed. Higher blood lactate was observed in Caucasians than in black Africans for POs over the load range from 4 kg up to the maximal power. However, PO and Quad RMS values were similar in Caucasians and black Africans. They also had similar lean leg volume (LLV) and consequently produced similar PO/LLV and Quad RMS/LLV values. Overall, our results suggest that Caucasians and black Africans matched for stature, VO(2max), and training background have similar PO and Quad RMS values, but different blood lactate concentrations during brief, intermittent, intense exercise performed on a cycloergometer.

  9. Absolute reliability of hamstring to quadriceps strength imbalance ratios calculated using peak torque, joint angle-specific torque and joint ROM-specific torque values.

    PubMed

    Ayala, F; De Ste Croix, M; Sainz de Baranda, P; Santonja, F

    2012-11-01

    The main purpose of this study was to determine the absolute reliability of conventional (H/Q(CONV)) and functional (H/Q(FUNC)) hamstring to quadriceps strength imbalance ratios calculated using peak torque values, 3 different joint angle-specific torque values (10°, 20° and 30° of knee flexion) and 4 different joint ROM-specific average torque values (0-10°, 11-20°, 21-30° and 0-30° of knee flexion) adopting a prone position in recreational athletes. A total of 50 recreational athletes completed the study. H/Q(CONV) and H/Q(FUNC) ratios were recorded at 3 different angular velocities (60, 180 and 240°/s) on 3 different occasions with a 72-96 h rest interval between consecutive testing sessions. Absolute reliability was examined through typical percentage error (CVTE), percentage change in the mean (CM) and intraclass correlations (ICC) as well as their respective confidence limits. H/Q(CONV) and H/Q(FUNC) ratios calculated using peak torque values showed moderate reliability values, with CM scores lower than 2.5%, CV(TE) values ranging from 16 to 20% and ICC values ranging from 0.3 to 0.7. However, poor absolute reliability scores were shown for H/Q(CONV) and H/Q(FUNC) ratios calculated using joint angle-specific torque values and joint ROM-specific average torque values, especially for H/Q(FUNC) ratios (CM: 1-23%; CV(TE): 22-94%; ICC: 0.1-0.7). Therefore, the present study suggests that the CV(TE) values reported for H/Q(CONV) and H/Q(FUNC) (≈18%) calculated using peak torque values may be sensitive enough to detect large changes usually observed after rehabilitation programmes but not acceptable to examine the effect of preventitive training programmes in healthy individuals. The clinical reliability of hamstring to quadriceps strength ratios calculated using joint angle-specific torque values and joint ROM-specific average torque values are questioned and should be re-evaluated in future research studies.

  10. [Transdisciplinary Approach for Sarcopenia. Sarcopenia and physical disability in older adults].

    PubMed

    Ikezoe, Tome

    2014-10-01

    We investigated the effects of age on muscle atrophy and the relationship of locomotor ability with the sarcopenia in trunk and lower-limb muscle using ultrasound. Age-related muscle atrophy in elderly women was greatest for the psoas major and internal oblique muscles among the trunk and lower limb muscles. The age-related decline in gluteus medius muscle was closely associated with daily physical activity. Physical disability influenced muscle atrophy in the trunk and lower limbs, especially in the quadriceps femoris, soleus, transversus abdominis and lumbar multifidus muscles among elderly women. These findings may be a useful guideline for muscle strength training to prevent physical disability in the elderly people.

  11. Evaluating the Influence of Massage on Leg Strength, Swelling, and Pain Following a Half-Marathon

    PubMed Central

    Dawson, Lance G.; Dawson, Kimberley A.; Tiidus, Peter M.

    2004-01-01

    Massage therapy is commonly used following endurance running races with the expectation that it will enhance post-run recovery of muscle function and reduce soreness. A limited number of studies have reported little or no influence of massage therapy on post-exercise muscle recovery. However, no studies have been conducted in a field setting to assess the potential for massage to influence muscle recovery following an actual endurance running race. To evaluate the potential for repeated massage therapy interventions to influence recovery of quadriceps and hamstring muscle soreness, recovery of quadriceps and hamstring muscle strength and reduction of upper leg muscle swelling over a two week recovery period following an actual road running race. Twelve adult recreational runners (8 male, 4 female) completed a half marathon (21.1 km) road race. On days 1,4, 8, and 11 post-race, subjects received 30 minutes of standardized massage therapy performed by a registered massage therapist on a randomly assigned massage treatment leg, while the other (control) leg received no massage treatment. Two days prior to the race (baseline) and preceding the treatments on post-race days 1, 4, 8, and 11 the following measures were conducted on each of the massage and control legs: strength of quadriceps and hamstring muscles, leg swelling, and soreness perception. At day 1, post-race quadriceps peak torque was significantly reduced (p < 0.05), and soreness and leg circumference significantly elevated (p < 0.05) relative to pre-race values with no difference between legs. This suggested that exercise-induced muscle disruption did occur. Comparing the rate of return to baseline measures between the massaged and control legs, revealed no significant differences (p > 0.05). All measures had returned to baseline at day 11. Massage did not affect the recovery of muscles in terms of physiological measures of strength, swelling, or soreness. However, questionnaires revealed that 7 of the 12

  12. [The influence of vibration on spinal alpha-motoneurons excitability in static conditions and during evoked stepping in human].

    PubMed

    Solopova, I A; Selionov, V A

    2012-01-01

    In healthy human the excitability of spinal alpha-motoneurons under application of vibrostimulation (20-60 Hz) to different leg muscles was investigated both in stationary condition and during stepping movements caused by vibration in the condition of suspended leg. In 15 subjects the amplitude of H-reflex were compared under vibration of rectus femoris (RF) and biceps femoris (BF) muscles of left leg as well during vibration of rectus femoris of contralateral, motionless leg in three spatial positions: upright, supine and on right side of body with suspended left leg. In dynamic conditions the amount of H-reflex was compared during evoked and voluntary stepping at 8 intervals of step cycle. In all body positions the vibration of each ipsilateral leg muscles caused significant suppression of H-reflex, this suppression was more prominent in the air-stepping conditions. The vibration of contralateral leg RF muscle had a weak influence on the amplitude of H-reflex. In 7 subjects the muscle vibration of ipsilateral and contralateral legs generated stepping movements. During evoked "air-stepping" H-reflex had different amplitudes in different phases of step cycle. At the same time the differences between responses under voluntary and non-voluntary stepping were revealed only in stance phase. Thus, different degree of H-reflex suppression by vibration under different body position in space depends on, it seems to be, from summary afferent inflows to spinal cord interneurons, which participate in regulation of posture and locomotion. Seemingly, the increasing of spinal cord neurons excitability occurs under involuntary air-stepping in swing phase, which is necessary for activation of locomotor automatism under unloading leg conditions.

  13. Effect of ThermaCare HeatWraps and Icy Hot Cream/Patches on Skin and Quadriceps Muscle Temperature and Blood Flow

    PubMed Central

    Petrofsky, Jerrold Scott; Laymon, Michael; Berk, Lee; Bains, Gurinder

    2016-01-01

    Objectives The purpose of this study was to compare the effects of over-the-counter treatments—ThermaCare HeatWraps (chemical reaction to produce heat above the skin), Icy Hot Patch, and Icy Hot Cream (topically applied menthol)—on skin and deep tissue temperature. Methods This was a longitudinal crossover study. On each of 3 days, a ThermaCare HeatWrap, Icy Hot Cream, or Icy Hot Patch was applied randomly over the quadriceps muscle in 15 healthy volunteers with normal body mass. Skin and muscle temperature and blood flow were measured by laser flowmetry every 15 minutes for 2 hours. Results After 2 hours, mean temperature decreased by 2.1°C (7.0%; P = .02) in skin and 1.0°C (2.9%; P = .01) in muscle with Icy Hot Cream. Icy Hot Patch decreased skin and muscle temperature by 1.7°C (5.4%; P = .03) and 1.3°C (3.8%; P = .01), respectively. In contrast, ThermaCare raised skin and muscle temperature by 7.8°C (25.8%; P = .001) and 2.7°C (7.7%; P = .002), respectively; both were significantly warmer with ThermaCare vs either Icy Hot product (all P < .007). Icy Hot products produced a net decrease in skin blood flow (Cream: 56.7 flux [39.3%; P = .003]; Patch: 19.1 flux [16.7%; P = .045]). Muscle blood flow decreased with the Patch (6.7 flux [7.0%; P = .02]). After a period of fluctuations, Icy Hot Cream produced a net increase vs baseline of 7.0 flux (16.9%; P = .02). ThermaCare more than doubled blood flow in skin (83.3 flux [109.7%; P = .0003]) and muscle (25.1 flux [148.5%; P = .004]). Conclusions In this group of 15 healthy volunteers, ThermaCare HeatWraps provided the greatest degree of tissue warming and increase in tissue blood flow. PMID:27069427

  14. POSTERIOR CRUCIATE LIGAMENT RECONSTRUCTION WITH AUTOGRAFT OF THE DOUBLE SEMITENDINOSUS MUSCLES AND MIDDLE THIRD OF THE QUADRICEPS TENDON WITH DOUBLE FEMORAL AND SINGLE TIBIAL TUNNELS: CLINICAL RESULTS IN TWO YEARS FOLLOW UP

    PubMed Central

    Cury, Ricardo de Paula Leite; Severino, Nilson Roberto; Camargo, Osmar Pedro Arbix; Aihara, Tatsuo; de Oliveira, Victor Marques; Avakian, Roger

    2015-01-01

    Objective: To evaluate the surgical aspects that may offer good anatomic and functional results in posterior cruciate ligament (PCL) reconstruction using an autologous graft of the quadriceps tendon and double semitendinosus through a double femoral tunnel. Methods: Fourteen patients with isolated PCL lesions, instability and pain were operated on by arthroscopy and evaluated according to the International Knee Documentation Committee (IKDC) and Lysholm scales. Posterior knee laxity was examined with a KT1000 arthrometer. Results: The mean postoperative posterior side-to-side difference was between 0-2 mm in 57.1% of patients and between 3 and 5 mm in 35.7% of cases. The average Lysholm score was 93 points in the final follow-up. In the IKDC evaluation, 3 patients were graded A, 10 were graded B, and 1 patient was graded C. Conclusions: Double bundle arthroscopic PCL reconstruction based on the anatomical positioning of the tunnels, with double semitendinosus tendon and single quadriceps, provides a clinically evident reduction in symptoms and restores satisfactory stability, although no statistically significant difference was found due to the small sample. PMID:27027083

  15. Whole-body vibration does not influence knee joint neuromuscular function or proprioception.

    PubMed

    Hannah, R; Minshull, C; Folland, J P

    2013-02-01

    This study examined the acute effects of whole-body vibration (WBV) on knee joint position sense and indices of neuromuscular function, specifically strength, electromechanical delay and the rate of force development. Electromyography and electrically evoked contractions were used to investigate neural and contractile responses to WBV. Fourteen healthy males completed two treatment conditions on separate occasions: (1) 5 × 1 min of unilateral isometric squat exercise on a synchronous vibrating platform [30 Hz, 4 mm peak-to-peak amplitude] (WBV) and (2) a control condition (CON) of the same exercise without WBV. Knee joint position sense (joint angle replication task) and quadriceps neuromuscular function were assessed pre-, immediately-post and 1 h post-exercise. During maximum voluntary knee extensions, the peak force (PF(V)), electromechanical delay (EMD(V)), rate of force development (RFD(V)) and EMG of the quadriceps were measured. Twitch contractions of the knee extensors were electrically evoked to assess EMD(E) and RFD(E). The results showed no influence of WBV on knee joint position, EMD(V), PF(V) and RFD(V) during the initial 50, 100 or 150 ms of contraction. Similarly, electrically evoked neuromuscular function and neural activation remained unchanged following the vibration exercise. A single session of unilateral WBV did not influence any indices of thigh muscle neuromuscular performance or knee joint proprioception.

  16. Importance of correcting isokinetic peak torque for the effect of gravity when calculating knee flexor to extensor muscle ratios.

    PubMed

    Fillyaw, M; Bevins, T; Fernandez, L

    1986-01-01

    The purpose of our investigation was to compare, for the hamstring and quadriceps femoris muscles, peak torque values uncorrected for gravity with the peak torque values corrected for gravity and to determine the effect of making this correction on the hamstring to quadriceps femoris muscle peak torque ratio at slow and fast isokinetic speeds. We measured peak torques isokinetically at 60 degrees/sec (slow) and 240 degrees/sec (fast) in 25 female university soccer players. The gravity effect torque (GET) is the torque resulting from the effect of gravity on the combined weight of the leg and dynamometer arm at the precise angle of extension and flexion peak torque. The GET was added to the measured quadriceps femoris muscle peak torque and subtracted from the hamstring muscle peak torque to yield gravity corrected values. Failure to consider GET greatly underestimated quadriceps femoris muscle torque and overestimated hamstring muscle torque and the ratio between these torques at both speeds. Whereas the uncorrected hamstring to quadriceps femoris muscle peak torque ratio increased as speeds went from 60 degrees/sec to 240 degrees/sec, the gravity corrected ratio significantly decreased. Clinicians must remember the importance of making the gravity correction in patients with reduced torque output where the gravitational torque is a greater percentage of the measured torque to ascertain correctly the relative strength of antagonists inversely affected by gravity.

  17. Dental occlusion influences knee muscular performances in asymptomatic females.

    PubMed

    Grosdent, Stéphanie; O'Thanh, Roseline; Domken, Olivier; Lamy, Marc; Croisier, Jean-Louis

    2014-02-01

    Some authors claim that occlusal appliances can enhance athletic performance. Therefore, this study investigated the influence of dental occlusion on knee muscle strength performance. Twelve healthy female subjects (mean age, 24.1 ± 3.1 years) without temporomandibular joint dysfunction participated in this study. Isokinetic quadriceps and hamstring strength were assessed in relation to 3 randomized jaw conditions: mouth closed in maximum intercuspidation without splint, mouth closed on a balanced splint which optimized contact over the dental arch, mouth closed on a piece of resin of 1 mm which created an imbalanced occlusion. Tests were performed at 60 and 240°·s in concentric and 30°·s in eccentric exertions. Concentric performances did not show any significant difference between the 3 jaw conditions (p > 0.05). In contrast, in the eccentric trials related to quadriceps performance, significant differences (p ≤ 0.05) were observed between the resin condition and the 2 other modalities (without splint or with a balanced splint). The imbalanced occlusion created by the resin component corresponded to an average decrease of 9% in eccentric peak torque. The eccentric hamstring peak torques also showed a significant difference (p ≤ 0.05) between measurements with splint and with resin (7% decrease when occlusion was imbalanced). In conclusion, among asymptomatic females, artificial imbalanced occlusion induces immediate and significant alteration of knee eccentric muscle performances. Therefore, occlusion examination should be undertaken on a regular and frequent basis for high-level athletes. Moreover, for athletes using mouthguards, muscular performance assessments should be planned with and without the dental protection.

  18. Dental occlusion influences knee muscular performances in asymptomatic females.

    PubMed

    Grosdent, Stéphanie; O'Thanh, Roseline; Domken, Olivier; Lamy, Marc; Croisier, Jean-Louis

    2013-09-14

    Some authors claim that occlusal appliances can enhance athletic performance. Therefore this study investigated the influence of dental occlusion on knee muscle strength performance. Twelve healthy female subjects (mean age 24.1 ± 3.1 years) without temporomandibular joint dysfunction participated in this study. Isokinetic quadriceps and hamstring strength were assessed in relation to three randomized jaw conditions: mouth closed in maximum intercuspidation without splint, mouth closed on a balanced splint which optimized contact over the dental arch, mouth closed on a piece of resin of 1 mm which created an imbalanced occlusion. Tests were performed at 60°/s and 240°/s in concentric and 30°/s in eccentric exertions. Concentric performances did not show any significant difference between the 3 jaw conditions (p > 0.05). By contrast, in the eccentric trials related to quadriceps performance, significant differences (p < 0.05) were observed between the resin condition and the two other modalities (without splint or with a balanced splint). The imbalanced occlusion created by the resin component corresponded to an average decrease of 9% in eccentric peak torque. The eccentric hamstring peak torques also showed a significant difference (p < 0.05) between measurements with splint and with resin (7% decrease when occlusion was imbalanced). In conclusion, among asymptomatic females, artificial imbalanced occlusion induces immediate and significant alteration of knee eccentric muscle performances. Therefore, occlusion examination should be undertaken on a regular and frequent basis for high-level athletes. Moreover, for athletes using mouthguards, muscular performance assessments should be planned with and without the dental protection.

  19. Development of a knee joint motion simulator to evaluate deep knee flexion of artificial knee joints.

    PubMed

    Takano, Y; Ueno, M; Kiguchi, K; Ito, J; Mawatari, M; Hotokebuchi, T

    2008-01-01

    A purpose of this study is to examine the effect that quadriceps femoris force gives to rotation angle and joint reaction force of total knee prosthesis during deep knee flexion such as a unique sitting style called 'seiza' in Japanese. For the evaluation, we developed the knee motion simulator which could bend to 180 degrees continually simulating the passive flexion performed by clinicians. A total knee prosthesis, which is a specially-devised posterior stabilized type and capable of flexion up to 180 degrees, was inserted into bone model. And this prosthesis pulled by three kinds of quadriceps femoris forces to perform parameter study. The results obtained in this study were showed the same tendency with those in the past cadaveric experiment. It is suggested that the rotation angle and joint reaction force of total knee prosthesis are affected by shape of prosthesis, a vector of quadriceps femoris force, and bony aliments during deep knee flexion.

  20. Sporadic Inclusion Body Myositis Manifesting as Isolated Muscle Weakness of the Finger Flexors Three Years after Disease Onset

    PubMed Central

    Suwa, Yuichi; Suzuki, Naoki; Soga, Temma; Harada, Ryuhei; Shibui, Aya; Kuroda, Hiroshi; Izumi, Rumiko; Tateyama, Maki; Nakashima, Ichiro; Sonoo, Masahiro; Aoki, Masashi

    2016-01-01

    Sporadic inclusion body myositis (sIBM) is a chronic progressive myopathy characterized by muscle weakness of both the quadriceps femoris and finger flexors. We herein present the case of a typical male patient with sIBM, which manifested as the isolated weakness of the finger flexors three years after the disease onset. We have identified several patients with sIBM in our cohort with muscle weakness of the flexors but not the quadriceps femoris. Examination of the flexor digitorum profundus muscle is important for the early and proper diagnosis of sIBM, even if a patient only presents with isolated finger flexor muscle weakness. PMID:27904121

  1. Elevated plasma corticosterone concentrations influence the onset of rigor mortis and meat color in broilers.

    PubMed

    Kannan, G; Heath, J L; Wabeck, C J; Owens, S L; Mench, J A

    1998-02-01

    This experiment was conducted to determine the effect of elevated plasma corticosterone (CORT) levels on meat quality characteristics. Male broilers (Arbor Acres) were either 1) fed a diet containing corticosterone (CORT) prior to processing, 2) transported by truck for 3 h before processing, or 3) processed without either of the above treatments. Six crates of birds (10 birds per crate; two crates per treatment) were stunned or killed using CO2 gas. Six birds per crate were processed and blood samples were collected during exsanguination for plasma CORT analysis. Meat samples were collected from carcasses either at 20 min or at 4 h post-mortem. At each sampling time (ST), Pectoralis superficialis samples were collected and either individually quick frozen (IQF) in liquid nitrogen or aged on ice (AOI) for 24 h prior to pH, ratio of inosine to adenosine nucleotides (R-value), cooking loss, shear value, and color analyses. The IQF Biceps femoris samples were used for pH, R-value, color, and heme pigment analysis. Mean (+/- SEM) CORT concentrations were 12.9+/-2.57, 11.7+/-1.38 and 7.9+/-0.79 ng/mL, respectively, in the CORT, transported, and control groups. There were significant treatment by ST (P < 0.05) and ST (P < 0.001) effects on the R-value of IQF P. superficialis samples. The CORT group had the highest L* value (P < 0.01) and the lowest a* value (P < 0.06). There was also a significant main effect of ST on shear values (P < 0.05) of AOI P. superficialis samples, with the means higher at 4 h than at 20 min post-mortem. The R-value of IQF B. femoris samples was markedly influenced by treatment (P < 0.001) and ST (P < 0.001). The results indicate that artificially elevating circulating CORT concentrations results in lighter meat color in broilers.

  2. The effect of electrostimulation and high load exercises in patients with patellofemoral joint dysfunction. A preliminary report.

    PubMed

    Vengust, R; Strojnik, V; Pavlovcic, V; Antolic, V; Zupanc, O

    2001-01-01

    Traditional conservative treatment for patellar disorders is successful in about 80 percents of cases. We introduced two new conservative treatment protocols for patellar pathology in order to further improve the success rate. The first protocol consisted of high load/low repetition quadriceps femoris training (10 patients) while the second enclosed selective electrostimulation of vastus medialis muscle (7 patients). Results were evaluated clinically and neurophysiologically. High load/low repetition training resulted in significant increase of maximal voluntary contraction of quadriceps muscle (P < 0.001). Significant gain of Activity (P = 0.017) and Kujala scores (P = 0.07) was observed in group with high load/low repetition quadriceps training compared to patients with electrostimulation. There was no significant change in neurophysiological or clinical status between the beginning and the end of treatment with electrostimulation. Our results indicate that high load/low repetition quadriceps femoris training poses an important alternative to traditional conservative treatment protocol for patellar disorders.

  3. Comparison of the Levels of Pro-Inflammatory Cytokines Released in the Vastus Lateralis Muscle of Patients with Fibromyalgia and Healthy Controls during Contractions of the Quadriceps Muscle – A Microdialysis Study

    PubMed Central

    Christidis, Nikolaos; Ghafouri, Bijar; Larsson, Anette; Palstam, Annie; Mannerkorpi, Kaisa; Bileviciute-Ljungar, Indre; Löfgren, Monika; Bjersing, Jan; Kosek, Eva; Gerdle, Björn; Ernberg, Malin

    2015-01-01

    Objective Fibromyalgia is associated with central hyperexcitability, but it is suggested that peripheral input is important to maintain central hyperexcitability. The primary aim was to investigate the levels of pro-inflammatory cytokines released in the vastus lateralis muscle during repetitive dynamic contractions of the quadriceps muscle in patients with fibromyalgia and healthy controls. Secondarily, to investigate if the levels of pro-inflammatory cytokines were correlated with pain or fatigue during these repetitive dynamic contractions. Material and Methods 32 women with fibromyalgia and 32 healthy women (controls) participated in a 4 hour microdialysis session, to sample IL-1β, IL-6, IL-8, and TNF from the most painful point of the vastus lateralis muscle before, during and after 20 minutes of repeated dynamic contractions. Pain (visual analogue scale; 0–100) and fatigue Borg’s Rating of Perceived Exertion Scale; 6–20) were assessed before and during the entire microdialysis session. Results The repetitive dynamic contractions increased pain in the patients with fibromyalgia (P < .001) and induced fatigue in both groups (P < .001). Perceived fatigue was significantly higher among patients with fibromyalgia than controls (P < .001). The levels of IL-1β did not change during contractions in either group. The levels of TNF did not change during contractions in patients with fibromyalgia, but increased in controls (P < .001) and were significantly higher compared to patients with fibromyalgia (P = .033). The levels of IL-6 and IL-8 increased in both groups alike during and after contractions (P’s < .001). There were no correlations between pain or fatigue and cytokine levels after contractions. Conclusion There were no differences between patients with fibromyalgia and controls in release of pro-inflammatory cytokines, and no correlations between levels of pro-inflammatory cytokines and pain or fatigue. Thus, this study indicates that IL-1β, IL-6, IL

  4. Changes in calsequestrin, TNF-α, TGF-β and MyoD levels during the progression of skeletal muscle dystrophy in mdx mice: a comparative analysis of the quadriceps, diaphragm and intrinsic laryngeal muscles.

    PubMed

    Barros Maranhão, Juliana; de Oliveira Moreira, Drielen; Maurício, Adriana Fogagnolo; de Carvalho, Samara Camaçari; Ferretti, Renato; Pereira, Juliano Alves; Santo Neto, Humberto; Marques, Maria Julia

    2015-10-01

    In Duchenne muscular dystrophy (DMD), the search for new biomarkers to follow the evolution of the disease is of fundamental importance in the light of the evolving gene and pharmacological therapies. In addition to the lack of dystrophin, secondary events including changes in calcium levels, inflammation and fibrosis greatly contribute to DMD progression and the molecules involved in these events may represent potential biomarkers. In this study, we performed a comparative evaluation of the progression of dystrophy within muscles that are differently affected by dystrophy (diaphragm; DIA and quadriceps; QDR) or spared (intrinsic laryngeal muscles) using the mdx mice model of DMD. We assessed muscle levels of calsequestrin (calcium-related protein), tumour necrosis factor (TNF-α; pro-inflammatory cytokine), tumour growth factor (TGF-β; pro-fibrotic factor) and MyoD (muscle proliferation) vs. histopathology at early (1 and 4 months of age) and late (9 months of age) stages of dystrophy. Fibrosis was the primary feature in the DIA of mdx mice (9 months: 32% fibrosis), which was greater than in the QDR (9 months: 0.6% fibrosis). Muscle regeneration was the primary feature in the QDR (9 months: 90% of centrally nucleated fibres areas vs. 33% in the DIA). The QDR expressed higher levels of calsequestrin than the DIA. Laryngeal muscles showed normal levels of TNF-α, TGF-β and MyoD. A positive correlation between histopathology and cytokine levels was observed only in the diaphragm, suggesting that TNF-α and TGF-β serve as markers of dystrophy primarily for the diaphragm.

  5. Strength After Bouts of Eccentric or Concentric Actions

    NASA Technical Reports Server (NTRS)

    Golden, Catherine L.; Dudley, Gary A.

    1992-01-01

    This study examined the influence of an initial bout of eccentric or concentric actions and a subsequent bout of eccentric actions on muscular strength. Twenty-four healthy males, 24-45 yr old, were placed in three groups that performed eccentric actions in bouts 1 and 2 (ECC/ECC, N = 8), concentric actions in bout 1, and eccentric actions in bout 2 (CON/ECC, N = 8) or served as controls (N = 8). Bouts involved unilateral actions with the left and right quadriceps femoris. Ten sets of 10 repetitions with an initial resistance equal to 85% of the eccentric or concentric one repetition maximum (1 RM) were performed for each bout. Three minutes of rest were given between sets and 3 wk between bouts. Two weeks before bout 1 and 1, 4, 7, and 10 d after bouts 1 and 2, eccentric and concentric 1 RM were measured for the right quadriceps femoris and a speed-torque relation established for the left quadriceps femoris. Eccentric and concentric 1 RM decreased (P less than 0.05) 32% 1 d after bout 1 for group ECC/ECC. The speed-torque relation was down-shifted (P less than 0.05) 38%. Eccentric 1 RM and eccentric and isometric torque returned to normal 6 d later. Concentric 1 RM and torque at 3.14 rad-s(exp -1) had not recovered on day 10 (-7% for both, P less than 0.05). Decreases in strength after bout 2 for group ECC/ECC only occurred on day 1 (-9% for concentric 1 RM and 16% downshift of the speed- torque relation). Group CONIECC showed the opposite responses; marked decreases in strength after bout 2 but not bout 1. The results indicate that the initial decrease in strength after performance of a novel bout of eccentric exercise is comparable for eccentric, concentric and isometric muscle actions. Recovery of strength, however, appears to occur more rapidly for eccentric and isometric actions. They suggest that performance of a prior bout of eccentric but not concentric actions, as done in this study, can essentially eradicate decreases in strength after a subsequent bout

  6. Oxidative damage to poultry, pork, and beef during frozen storage through the analysis of novel protein oxidation markers.

    PubMed

    Utrera, Mariana; Estévez, Mario

    2013-08-21

    The susceptibility of meats from different animal species (beef quadriceps femoris, porcine longissimus dorsi, and chicken pectoralis major) to undergo protein oxidation during frozen storage (20 weeks/-18 °C) was studied through the analysis of novel oxidation markers. Frozen storage induced protein carbonylation (α-aminoadipic and γ-glutamic semialdehydes), carboxylation (α-aminoadipic acid), and formation of Schiff bases in meat from the three species. Major rates of protein and lipid oxidation products [thiobarbituric-acid-reactive substances (TBARS) and hexanal] were found in beef patties. Among the endogenous factors having a potential influence on the susceptibility of meat to undergo protein oxidation, heme iron seemed to play a major role. The present study illustrates the severe chemical modifications induced by oxidative stress during frozen storage of ground meat and provides original insight into the underlying mechanisms and factors.

  7. No Influence of Transcutaneous Electrical Nerve Stimulation on Exercise-Induced Pain and 5-Km Cycling Time-Trial Performance

    PubMed Central

    Hibbert, Andrew W.; Billaut, François; Varley, Matthew C.; Polman, Remco C. J.

    2017-01-01

    Introduction: Afferent information from exercising muscle contributes to the sensation of exercise-induced muscle pain. Transcutaneous electrical nerve stimulation (TENS) delivers low–voltage electrical currents to the skin, inhibiting nociceptive afferent information. The use of TENS in reducing perceptions of exercise-induced pain has not yet been fully explored. This study aimed to investigate the effect of TENS on exercise-induced muscle pain, pacing strategy, and performance during a 5-km cycling time trial (TT). Methods: On three separate occasions, in a single-blind, randomized, and cross-over design, 13 recreationally active participants underwent a 30-min TENS protocol, before performing a 5-km cycling TT. TENS was applied to the quadriceps prior to exercise under the following conditions; control (CONT), placebo with sham TENS application (PLAC), and an experimental condition with TENS application (TENS). Quadriceps fatigue was assessed with magnetic femoral nerve stimulation assessing changes in potentiated quadriceps twitch force at baseline, pre and post exercise. Subjective scores of exertion, affect and pain were taken every 1-km. Results: During TTs, application of TENS did not influence pain perceptions (P = 0.68, ηp2 = 0.03). There was no significant change in mean power (P = 0.16, ηp2 = 0.16) or TT duration (P = 0.17, ηp2 = 0.14), although effect sizes were large for these two variables. Changes in power output were not significant but showed moderate effect sizes at 500-m (ηp2 = 0.10) and 750-m (ηp2 = 0.10). Muscle recruitment as inferred by electromyography data was not significant, but showed large effect sizes at 250-m (ηp2 = 0.16), 500-m (ηp2 = 0.15), and 750-m (ηp2 = 0.14). This indicates a possible effect for TENS influencing performance up to 1-km. Discussion: These findings do not support the use of TENS to improve 5-km TT performance. PMID:28223939

  8. No Influence of Transcutaneous Electrical Nerve Stimulation on Exercise-Induced Pain and 5-Km Cycling Time-Trial Performance.

    PubMed

    Hibbert, Andrew W; Billaut, François; Varley, Matthew C; Polman, Remco C J

    2017-01-01

    Introduction: Afferent information from exercising muscle contributes to the sensation of exercise-induced muscle pain. Transcutaneous electrical nerve stimulation (TENS) delivers low-voltage electrical currents to the skin, inhibiting nociceptive afferent information. The use of TENS in reducing perceptions of exercise-induced pain has not yet been fully explored. This study aimed to investigate the effect of TENS on exercise-induced muscle pain, pacing strategy, and performance during a 5-km cycling time trial (TT). Methods: On three separate occasions, in a single-blind, randomized, and cross-over design, 13 recreationally active participants underwent a 30-min TENS protocol, before performing a 5-km cycling TT. TENS was applied to the quadriceps prior to exercise under the following conditions; control (CONT), placebo with sham TENS application (PLAC), and an experimental condition with TENS application (TENS). Quadriceps fatigue was assessed with magnetic femoral nerve stimulation assessing changes in potentiated quadriceps twitch force at baseline, pre and post exercise. Subjective scores of exertion, affect and pain were taken every 1-km. Results: During TTs, application of TENS did not influence pain perceptions (P = 0.68, [Formula: see text] = 0.03). There was no significant change in mean power (P = 0.16, [Formula: see text] = 0.16) or TT duration (P = 0.17, [Formula: see text] = 0.14), although effect sizes were large for these two variables. Changes in power output were not significant but showed moderate effect sizes at 500-m ([Formula: see text] = 0.10) and 750-m ([Formula: see text] = 0.10). Muscle recruitment as inferred by electromyography data was not significant, but showed large effect sizes at 250-m ([Formula: see text] = 0.16), 500-m ([Formula: see text] = 0.15), and 750-m ([Formula: see text] = 0.14). This indicates a possible effect for TENS influencing performance up to 1-km. Discussion: These findings do not support the use of TENS to

  9. Influence of transcutaneous electrical stimulation on heterotopic ossification: an experimental study in Wistar rats

    PubMed Central

    Zotz, T.G.G.; de Paula, J.B.

    2015-01-01

    Heterotopic ossification (HO) is a metaplastic biological process in which there is newly formed bone in soft tissues, resulting in joint mobility deficit and pain. Different treatment modalities have been tried to prevent HO development, but there is no consensus on a therapeutic approach. Since electrical stimulation is a widely used resource in physiotherapy practice to stimulate joint mobility, with analgesic and anti-inflammatory effects, its usefulness for HO treatment was investigated. We aimed to identify the influence of electrical stimulation on induced HO in Wistar rats. Thirty-six male rats (350-390 g) were used, and all animals were anesthetized for blood sampling before HO induction, to quantify the serum alkaline phosphatase. HO induction was performed by bone marrow implantation in both quadriceps of the animals, which were then divided into 3 groups: control (CG), transcutaneous electrical nerve stimulation (TENS) group (TG), and functional electrical stimulation (FES) group (FG) with 12 rats each. All animals were anesthetized and electrically stimulated twice per week, for 35 days from induction day. After this period, another blood sample was collected and quadriceps muscles were bilaterally removed for histological and calcium analysis and the rats were killed. Calcium levels in muscles showed significantly lower results when comparing TG and FG (P<0.001) and between TG and CG (P<0.001). Qualitative histological analyses confirmed 100% HO in FG and CG, while in TG the HO was detected in 54.5% of the animals. The effects of the muscle contractions caused by FES increased HO, while anti-inflammatory effects of TENS reduced HO. PMID:26292223

  10. Influence of transcutaneous electrical stimulation on heterotopic ossification: an experimental study in Wistar rats.

    PubMed

    Zotz, T G G; Paula, J B de

    2015-11-01

    Heterotopic ossification (HO) is a metaplastic biological process in which there is newly formed bone in soft tissues, resulting in joint mobility deficit and pain. Different treatment modalities have been tried to prevent HO development, but there is no consensus on a therapeutic approach. Since electrical stimulation is a widely used resource in physiotherapy practice to stimulate joint mobility, with analgesic and anti-inflammatory effects, its usefulness for HO treatment was investigated. We aimed to identify the influence of electrical stimulation on induced HO in Wistar rats. Thirty-six male rats (350-390 g) were used, and all animals were anesthetized for blood sampling before HO induction, to quantify the serum alkaline phosphatase. HO induction was performed by bone marrow implantation in both quadriceps of the animals, which were then divided into 3 groups: control (CG), transcutaneous electrical nerve stimulation (TENS) group (TG), and functional electrical stimulation (FES) group (FG) with 12 rats each. All animals were anesthetized and electrically stimulated twice per week, for 35 days from induction day. After this period, another blood sample was collected and quadriceps muscles were bilaterally removed for histological and calcium analysis and the rats were killed. Calcium levels in muscles showed significantly lower results when comparing TG and FG (P<0.001) and between TG and CG (P<0.001). Qualitative histological analyses confirmed 100% HO in FG and CG, while in TG the HO was detected in 54.5% of the animals. The effects of the muscle contractions caused by FES increased HO, while anti-inflammatory effects of TENS reduced HO.

  11. Creatine Loading, Resistance Exercise Performance, and Muscle Mechanics.

    ERIC Educational Resources Information Center

    Stevenson, Scott W.; Dudley, Gary A.

    2001-01-01

    Examined whether creatine (CR) monohydrate loading would alter resistance exercise performance, isometric strength, or in vivo contractile properties of the quadriceps femoris muscle compared with placebo loading in resistance-trained athletes. Overall, CR loading did not provide an ergogenic benefit for the unilateral dynamic knee extension…

  12. A Predictive Mathematical Model of Muscle Forces for Children with Cerebral Palsy

    ERIC Educational Resources Information Center

    Lee, Samuel C. K.; Ding, Jun; Prosser, Laura A.; Wexler, Anthony S.; Binder-Macleod, Stuart A.

    2009-01-01

    Aim: The purpose of this study was to determine if our previously developed muscle model could be used to predict forces of the quadriceps femoris and triceps surae muscles of children with spastic diplegic cerebral palsy (CP). Method: Twenty-two children with CP (12 males, 10 females; mean age 10y, SD 2y, range 7-13y; Gross Motor Function…

  13. Altering prosthetic foot stiffness influences foot and muscle function during below-knee amputee walking: a modeling and simulation analysis.

    PubMed

    Fey, Nicholas P; Klute, Glenn K; Neptune, Richard R

    2013-02-22

    Most prosthetic feet are designed to improve amputee gait by storing and releasing elastic energy during stance. However, how prosthetic foot stiffness influences muscle and foot function is unclear. Identifying these relationships would provide quantitative rationale for prosthetic foot prescription that may lead to improved amputee gait. The purpose of this study was to identify the influence of altered prosthetic foot stiffness on muscle and foot function using forward dynamics simulations of amputee walking. Three 2D muscle-actuated forward dynamics simulations of unilateral below-knee amputee walking with a range of foot stiffness levels were generated, and muscle and prosthetic foot contributions to body support and propulsion and residual leg swing were quantified. As stiffness decreased, the prosthetic keel provided increased support and braking (negative propulsion) during the first half of stance while the heel contribution to support decreased. During the second half of stance, the keel provided decreased propulsion and increased support. In addition, the keel absorbed less power from the leg, contributing more to swing initiation. Thus, several muscle compensations were necessary. During the first half of stance, the residual leg hamstrings provided decreased support and increased propulsion. During the second half of stance, the intact leg vasti provided increased support and the residual leg rectus femoris transferred increased energy from the leg to the trunk for propulsion. These results highlight the influence prosthetic foot stiffness has on muscle and foot function throughout the gait cycle and may aid in prescribing feet of appropriate stiffness.

  14. Finite element analysis to characterize how varying patellar loading influences pressure applied to cartilage: model evaluation.

    PubMed

    Shah, Kushal S; Saranathan, Archana; Koya, Bharath; Elias, John J

    2015-01-01

    A finite element analysis (FEA) modeling technique has been developed to characterize how varying the orientation of the patellar tendon influences the patellofemoral pressure distribution. To evaluate the accuracy of the technique, models were created from MRI images to represent five knees that were previously tested in vitro to determine the influence of hamstrings loading on patellofemoral contact pressures. Hamstrings loading increased the lateral and posterior orientation of the patellar tendon. Each model was loaded at 40°, 60°, and 80° of flexion with quadriceps force vectors representing the experimental loading conditions. The orientation of the patellar tendon was represented for the loaded and unloaded hamstrings conditions based on experimental measures of tibiofemoral alignment. Similar to the experimental data, simulated loading of the hamstrings within the FEA models shifted the center of pressure laterally and increased the maximum lateral pressure. Significant (p < 0.05) differences were identified for the center of pressure and maximum lateral pressure from paired t-tests carried out at the individual flexion angles. The ability to replicate experimental trends indicates that the FEA models can be used for future studies focused on determining how variations in the orientation of the patellar tendon related to anatomical or loading variations or surgical procedures influence the patellofemoral pressure distribution.

  15. Influence of different racing positions on mechanical and electromyographic patterns during pedalling.

    PubMed

    Dorel, S; Couturier, A; Hug, F

    2009-02-01

    The aim of this study was to test the hypothesis that, in comparison with standard postures, aero posture (AP) would modify the coordination of lower limb muscles during pedalling and consequently would influence the pedal force production. Twelve triathletes were asked to pedal at an intensity near the ventilatory threshold (VT+Delta20%) and at an intenisty corresponding to the respiratory compensation point (RCP). For each intensity, subjects were tested under three positions: (1) upright posture (UP), (2) dropped posture (DP), and (3) AP. Gas exchanges, surface electromyography and pedal effective force were continuously recorded. No significant difference was found for the gas-exchange variables among the three positions. Data illustrate a significant increase [gluteus maximus (GMax), vastus medialis (VM)] and decrease [rectus femoris (RF)] in electromyography (EMG) activity level in AP compared with UP at RCP. A significant shift forward of the EMG patterns (i.e. later onset of activation) was observed for RF (at VT+Delta20% and RCP), GMax, VL, and VM (at RCP) in AP compared with UP. These EMG changes are closely related to alteration of force profile in AP (higher downstroke positive peak force, lower upstroke negative peak force, and later occurrence of these peaks along the crank cycle).

  16. Influence on muscle oxygenation to EMG parameters at different skeletal muscle contraction

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Song, Gaoqing

    2010-02-01

    The purpose of this study is to investigate the influence of muscle oxygenation on EMG parameters during isometric and incremental exercises and to observe the relationship between EMG parameters and muscle oxygenation. Twelve rowers took part in the tests. Near infrared spectrometer was utilized for measurements of muscle oxygenation on lateral quadriceps. sEMG measurement is performed for EMG parameters during isometric and incremental exercises. Results indicated that Oxy-Hb decrease significantly correlated with IEMG, E/T ratio and frequency of impulse signal during 1/3 MVC and 2/3 MVC isometric exercise, and it is also correlated with IEMG, E/T ratio and frequency of impulse signal. Increase of IEMG occurred at the time after Oxy-Hb decrease during incremental exercise and highly correlated with BLa. It is concluded that no matter how heavy the intensity is, Oxy-Hb dissociation may play an important role in affecting EMG parameters of muscle fatigue during isometric exercise. 2) EMG parameters may be influenced by Oxy-Hb dissociation and blood lactate concentration during dynamic exercise.

  17. Influence on muscle oxygenation to EMG parameters at different skeletal muscle contraction

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Song, Gaoqing

    2009-10-01

    The purpose of this study is to investigate the influence of muscle oxygenation on EMG parameters during isometric and incremental exercises and to observe the relationship between EMG parameters and muscle oxygenation. Twelve rowers took part in the tests. Near infrared spectrometer was utilized for measurements of muscle oxygenation on lateral quadriceps. sEMG measurement is performed for EMG parameters during isometric and incremental exercises. Results indicated that Oxy-Hb decrease significantly correlated with IEMG, E/T ratio and frequency of impulse signal during 1/3 MVC and 2/3 MVC isometric exercise, and it is also correlated with IEMG, E/T ratio and frequency of impulse signal. Increase of IEMG occurred at the time after Oxy-Hb decrease during incremental exercise and highly correlated with BLa. It is concluded that no matter how heavy the intensity is, Oxy-Hb dissociation may play an important role in affecting EMG parameters of muscle fatigue during isometric exercise. 2) EMG parameters may be influenced by Oxy-Hb dissociation and blood lactate concentration during dynamic exercise.

  18. Lumbosacral plexus compression by fetus: an unusual cause of radiculopathy during teenage pregnancy.

    PubMed

    Turgut, F; Turgut, M; Menteş, E

    1997-06-01

    A case is reported of a lumbosacral plexus compression by the fetus in a young 34-weeks pregnant woman, who had low-back pain and progressive muscular weakness of the leg. Neurological examination showed a grade IV motor weakness of the iliopsoas, quadriceps femoris and biceps femoris muscles. Mechanical stretch manoeuvers were negative. Electromyography revealed denervation activity in L4 and L5 muscles. Lumbosacral plexus radiculopathy was diagnosed. Although fetal compression appears to be an uncommon cause of lumbosacral radiculopathy during teenage pregnancy, both neurosurgeons and obstetricians should be aware of the possibility.

  19. Influence of pelvis position on the activation of abdominal and hip flexor muscles.

    PubMed

    Workman, J Chad; Docherty, David; Parfrey, Kevin C; Behm, David G

    2008-09-01

    A pelvic position has been sought that optimizes abdominal muscle activation while diminishing hip flexor activation. Thus, the objective of the study was to investigate the effect of pelvic position and the Janda sit-up on trunk muscle activation. Sixteen male volunteers underwent electromyographic (EMG) testing of their abdominal and hip flexor muscles during a supine isometric double straight leg lift (DSLL) with the feet held approximately 5 cm above a board. The second exercise (Janda sit-up) was a sit-up action where participants simultaneously contracted the hamstrings and the abdominal musculature while holding an approximately 45 degrees angle at the knee. Root mean square surface electromyography was calculated for the Janda sit-up and DSLL under 3 pelvic positions: anterior, neutral, and posterior pelvic tilt. The selected muscles were the upper and lower rectus abdominis (URA, LRA), external obliques, lower abdominal stabilizers (LAS), rectus femoris, and biceps femoris. The Janda sit-up position demonstrated the highest URA and LRA activation and the lowest rectus femoris activation. The Janda sit-up and the posterior tilt were significantly greater (p < 0.01 and p < 0.05, respectively) than the anterior tilt for the URA and LRA muscles. Activation levels of the URA and LRA in neutral pelvis were significantly (p < 0.01 and p < 0.05, respectively) less than the Janda sit-up position, but not significantly different from the posterior tilt. No significant differences in EMG activity were found for the external obliques or LAS. No rectus femoris differences were found in the 3 pelvis positions. The results of this study indicate that pelvic position had a significant effect on the activation of selected trunk and hip muscles during isometric exercise, and the activation of the biceps femoris during the Janda sit-up reduced the activation of the rectus femoris while producing high levels of activation of the URA and LRA.

  20. Atlas of the muscle motor points for the lower limb: implications for electrical stimulation procedures and electrode positioning.

    PubMed

    Botter, Alberto; Oprandi, Gianmosè; Lanfranco, Fabio; Allasia, Stefano; Maffiuletti, Nicola A; Minetto, Marco Alessandro

    2011-10-01

    The aim of the study was to investigate the uniformity of the muscle motor point location for lower limb muscles in healthy subjects. Fifty-three subjects of both genders (age range: 18-50 years) were recruited. The muscle motor points were identified for the following ten muscles of the lower limb (dominant side): vastus medialis, rectus femoris, and vastus lateralis of the quadriceps femoris, biceps femoris, semitendinosus, and semimembranosus of the hamstring muscles, tibialis anterior, peroneus longus, lateral and medial gastrocnemius. The muscle motor point was identified by scanning the skin surface with a stimulation pen electrode and corresponded to the location of the skin area above the muscle in which an electrical pulse evoked a muscle twitch with the least injected current. For each investigated muscle, 0.15 ms square pulses were delivered through the pen electrode at low current amplitude (<10 mA) and frequency (2 Hz). 16 motor points were identified in the 10 investigated muscles of almost all subjects: 3 motor points for the vastus lateralis, 2 motor points for rectus femoris, vastus medialis, biceps femoris, and tibialis anterior, 1 motor point for the remaining muscles. An important inter-individual variability was observed for the position of the following 4 out of 16 motor points: vastus lateralis (proximal), biceps femoris (short head), semimembranosus, and medial gastrocnemius. Possible implications for electrical stimulation procedures and electrode positioning different from those commonly applied for thigh and leg muscles are discussed.

  1. Early modification of stretch reflex in Parkinson's disease.

    PubMed

    Bergui, M; Paglia, G; Lopiano, L; Quattrocolo, G; Bergamini, L; Bergamasco, B

    1993-07-01

    We stretched quadriceps femoris in healthy subjects and in patients with a recent diagnosis of PD in order to assess whether modifications of the long-latency component of the stretch reflex is an early event in the course of Parkinson's disease (PD). We found a modified mechanical and electromyographic (EMG) behavior in stretching relaxed muscles of patients while voluntary activation greatly reduced differences between normal and Parkinsonian subjects, suggesting that a lower threshold of the response is an early sign in PD.

  2. The Myotoxic Effects of Microencapsulated Naproxen and Carrier Polymer After Intramuscular Injection in Rats

    DTIC Science & Technology

    1996-10-10

    diclofenac, piroxicam, ketoprofen , metamizol magnesium, and ketorolac into skeletal muscle (hindlimb) of rats. All of the NSAIDs produced some degree...was: 0.9% saline < ketorolac IOmglml < ketorolac 30mglml < ketoprofen 50mglml < formalin 10% < piroxicam 20mglml < diclofenac sodium 25mglml... ketoprofen 50mglml into the quadriceps femoris muscle group. All rats in their study were killed at 24 hours post-injection. The tissue samples were

  3. Mathematical modeling of the human knee joint

    SciTech Connect

    Ricafort, Juliet

    1996-05-01

    A model was developed to determine the forces exerted by several flexor and extensor muscles of the human knee under static conditions. The following muscles were studied: the gastrocnemius, biceps femoris, semitendinosus, semimembranosus, and the set of quadricep muscles. The tibia and fibula were each modeled as rigid bodies; muscles were modeled by their functional lines of action in space. Assumptions based on previous data were used to resolve the indeterminacy.

  4. [Monomelic segmental amyotrophy: a Spanish case involving the leg].

    PubMed

    Moreno Martinez, J M; Garcia de la Rocha, M L; Martin Araguz, A

    1990-01-01

    A 65-year old male presented with selective amyotrophy of the right lower limb which, after a progressive course of some months, had stabilized 12 years previously. Physical examination showed amyotrophy involving the gastrocnemius and the quadriceps extensor femoris without sensory impairment. EMG suggested motor neuron disease. This case meets Hirayama and Serratrice's criteria for benign chronic monomelic amyotrophy. We support the hypothesis of a casual vascular factor, as proposed by Hirayama.

  5. Influence of Gender and Muscle Architecture Asymmetry on Jump and Sprint Performance

    PubMed Central

    Mangine, Gerald T.; Fukuda, David H.; LaMonica, Michael B.; Gonzalez, Adam M.; Wells, Adam J.; Townsend, Jeremy R.; Jajtner, Adam R.; Fragala, Maren S.; Stout, Jeffrey R.; Hoffman, Jay R.

    2014-01-01

    Muscle architecture is a determinant for sprinting speed and jumping power, which may be related to anaerobic sports performance. In the present investigation, the relationships between peak (PVJP) and mean (MVJP) vertical jump power, 30m maximal sprinting speed (30M), and muscle architecture were examined in 28 college-aged, recreationally-active men (n = 14; 24.3 ± 2.2y; 89.1 ± 9.3kg; 1.80 ± 0.07 m) and women (n = 14; 21.5 ± 1.7y; 65.2 ± 12.4kg; 1.63 ± 0.08 m). Ultrasound measures of muscle thickness (MT), pennation angle (PNG), cross-sectional area (CSA), and echo intensity (ECHO) were collected from the rectus femoris (RF) and vastus lateralis (VL) of both legs; fascicle length (FL) was estimated from MT and PNG. Men possessed lower ECHO, greater muscle size (MT & CSA), were faster, and were more powerful (PVJP & MVJP) than women. Stepwise regression indicated that muscle size and quality influenced speed and power in men. In women, vastus lateralis asymmetry negatively affected PVJP (MT: r = –0.73; FL: r = –0.60) and MVJP (MT: r = –0.76; FL: r = –0.64), while asymmetrical ECHO (VL) and FL (RF) positively influenced MVJP (r = 0.55) and 30M (r = 0.57), respectively. Thigh muscle architecture appears to influence jumping power and sprinting speed, though the effect may vary by gender in recreationally-active adults. Appropriate assessment of these ultrasound variables in men and women prior to training may provide a more specific exercise prescription. Key points The manner in which thigh muscle architecture affects jumping power and sprinting speed varies by gender. In men, performance is influenced by the magnitude of muscle size and architecture. In women, asymmetrical muscle size and architectural asymmetry significantly influence performance. To develop effective and precise exercise prescription for the improvement of jumping power and/or sprinting speed, muscle architecture assessment prior to the onset of a training program is advised. PMID

  6. Influence of Lower Extremity Muscle Size and Quality on Stair-Climb Performance in Career Firefighters.

    PubMed

    Kleinberg, Craig R; Ryan, Eric D; Tweedell, Andrew J; Barnette, Timothy J; Wagoner, Chad W

    2016-06-01

    The purpose of this study was to examine the influence of lower extremity muscular size and quality on stair-climb performance (SCP) in career firefighters. Forty-six male career firefighters (age = 37.0 ± 7.2 years; stature = 180.2 ± 6.9 cm; body mass = 108.0 ± 19.8 kg) volunteered for this study. Panoramic ultrasound images of the vastus lateralis and rectus femoris were obtained to determine cross-sectional area (CSA) and echo intensity (EI) of each muscle. The CSA of each muscle was then summed together and normalized to body mass (CSA/BM [QCSA]). Additionally, EI was averaged across both muscles (QEI). Participants then performed a timed and weighted SCP assessment where they ascended and descended 26 stairs 4 times as quickly as possible while wearing a weighted vest (22.73 kg) to simulate the weight of their self-contained breathing apparatus and turnout gear. Bivariate correlations and stepwise regression analyses were used to examine the relationships among variables and the relative contributions of QCSA and QEI to SCP. Partial correlations were used to examine the relationship between QCSA and SCP and QEI and SCP while controlling for age and body mass index (BMI). The results indicated that QCSA and QEI were significantly related to SCP before (r = -0.492, p = 0.001; r = 0.363, p = 0.013, respectively) and after accounting for age and BMI (r = -0.324, p = 0.032; r = 0.413, p = 0.005, respectively). Both QCSA and QEI contributed significantly to the prediction of SCP (r = 0.560, p < 0.001). These findings indicate that lower extremity muscle size and quality are important contributors to critical firefighting tasks, which have been shown to be improved with resistance training.

  7. Acute effects of static stretching of hamstring on performance and ACL injury risk during stop-jump and cutting tasks in female athletes.

    PubMed

    Ruan, Mianfang; Zhang, Qiang; Wu, Xie

    2017-01-11

    There is limited research investigating antagonist stretch. The purpose of this study was to evaluate the influence of SSH on performance and ACL injury risk during stop-jump and 180° cutting tasks. Twelve female college athletes (age 20.8 ± 0.7 years; height 1.61 ± 0.05 m; mass 54.25 ± 4.22 kg) participated in this study. Subjects performed stop-jump and 180° cutting tasks under two conditions: after warm-up with 4×30 s SSH or after warm-up without SSH. Three-dimensional kinematic and kinetic data as well as EMG of biceps femoris (BF), rectus femoris (RF), vastus medialis (VM), and gastrocnemius medialis (GM) were collected during testing. SSH significantly enhanced jump height by 5.1% (P = 0.009), but did not change the takeoff speed of cutting. No significant changes in peak knee adduction moment or peak anterior tibia shear force were observed with SSH regardless of the task. The peak lateral tibia shear force during cutting was significantly (P = 0.036) reduced with SSH. The co-contraction of hamstring and quadriceps during the preactivation (stop-jump: P = 0.04; cutting: P = 0.05) and downward phases (stop-jump: P = 0.04; cutting: P = 0.05) was significantly reduced after SSH regardless of the task. The results suggest that SSH enhanced the performance of stop-jump due to decreased co-contraction of hamstring and quadriceps, but did not change the performance of cutting. In addition, SSH did not increase ACL injury risk during stop-jump and cutting tasks and even reduced medial-lateral knee loading during cutting.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND) , where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.

  8. The influence of patellofemoral joint contact geometry on the modeling of three dimensional patellofemoral joint forces.

    PubMed

    Powers, Christopher M; Chen, Yu-Jen; Scher, Irving; Lee, Thay Q

    2006-01-01

    The purpose of this study was to determine the influence of patellofemoral joint contact geometry on the modeling of three-dimensional patellofemoral joint forces. To achieve this goal, patellofemoral joint reaction forces (PFJRFs) that were measured from an in-vitro cadaveric set-up were compared to PFJRFs estimated from a computer model that did not consider patellofemoral joint contact geometry. Ten cadaver knees were used in this study. Each was mounted on a custom jig that was fixed to an Instron frame. Quadriceps muscle loads were accomplished using a pulley system and weights. The force in the patellar ligament was obtained using a buckle transducer. To quantify the magnitude and direction of the PFJRF, a six-axis load cell was incorporated into the femoral fixation system so that a rigid body assumption could be made. PFJRF data were obtained at 0 degrees , 20 degrees , 40 degrees and 60 degrees of knee flexion. Following in vitro testing, SIMM modeling software was used to develop computational models based on the three-dimensional coordinates (Microscribe digitizer) of individual muscle and patellar ligament force vectors obtained from the cadaver knees. The overall magnitude of the PFJRF estimated from the computer generated models closely matched the direct measurements from the in vitro set-up (Pearson's correlation coefficient, R(2)=0.91, p<0.001). Although the computational model accurately estimated the posteriorly directed forces acting on the joint, some discrepancies were noted in the forces acting in the superior and lateral directions. These differences however, were relatively small when expressed as a total of the overall PFJRF magnitude.

  9. Peer Influence and Recovery

    ERIC Educational Resources Information Center

    Collier, Crystal; Simpson, Shelly; Najera, John; Weiner, Lauren

    2012-01-01

    Research has shown that peer influence can be negative, by increasing the likelihood that a youth will engage in high-risk behaviors and make risky decisions. However, peer influence can also be positive and protect a youth from these same high-risk activities. This article examines the extent of peer influence and then describes the Alternative…

  10. Relationships Between Lower Extremity Alignment and the Quadriceps Angle

    PubMed Central

    Nguyen, Anh-Dung; Boling, Michelle C.; Levine, Beverly; Shultz, Sandra J.

    2010-01-01

    Objective To determine the extent to which select lower extremity alignment characteristics of the pelvis, hip, knee, and foot are related to the Q angle. Design Descriptive cohort study design. Setting Applied Neuromechanics Research Laboratory. Participants Two hundred eighteen participants (102 males, 116 females). Assessment of Risk Factors Eight clinical measures of static alignment of the left lower extremity were measured by a single examiner to determine the impact of lower extremity alignment on the magnitude of Q angle. Main Outcome Measures Q angle, pelvic angle, hip anteversion, tibiofemoral angle, genu recurvatum, tibial torsion, navicular drop, and femur and tibia length. Results Once all alignment variables were accounted for, greater tibiofemoral angle and femoral anteversion were significant predictors of greater Q angle in both males and females. Pelvic angle, genu recurvatum, tibial torsion, navicular drop, and femur to tibia length ratio were not significant independent predictors of Q angle in males or females. Conclusions Greater femoral anteversion and tibiofemoral angle result in greater Q angle, with changes in tibiofemoral angle having a substantially greater impact on the magnitude of the Q angle compared with femoral anteversion. As such, the Q angle seems to largely represent a frontal plane alignment measure. As many knee injuries seem to result from a combination of both frontal and transverse plane motions and forces, this may in part explain why Q angle has been found to be a poor independent predictor of lower extremity injury risk. PMID:19423972

  11. Quadriceps oxygenation changes during walking and running on a treadmill

    NASA Astrophysics Data System (ADS)

    Quaresima, Valentina; Pizzi, Assunta; De Blasi, Roberto A.; Ferrari, Adriano; de Angelis, Marco; Ferrari, Marco

    1995-04-01

    Vastus lateralis muscle oxygenation was investigated on volunteers as well as muscular dystrophy patients during a walking test, and on volunteers during a free running by a continuous wave near infrared instrument. The data were analyzed using an oxygenation index independent on pathlength changes. Walking did not significantly affect the oxygenation of volunteers and patients. A relative deoxygenation was found only during free running indicating an unbalance between oxygen supply and tissue oxygen extraction. Preliminary measurements of exercising muscle oxygen saturation were performed by a 110 MHz frequency-domain, multisource instrument.

  12. Recumbent vs. upright bicycles: 3D trajectory of body centre of mass, limb mechanical work, and operative range of propulsive muscles.

    PubMed

    Telli, Riccardo; Seminati, Elena; Pavei, Gaspare; Minetti, Alberto Enrico

    2017-03-01

    Recumbent bicycles (RB) are high performance, human-powered vehicles. In comparison to normal/upright bicycles (NB) the RB may allow individuals to reach higher speeds due to aerodynamic advantages. The purpose of this investigation was to compare the non-aerodynamic factors that may potentially influence the performance of the two bicycles. 3D body centre of mass (BCoM) trajectory, its symmetries, and the components of the total mechanical work necessary to sustain cycling were assessed through 3D kinematics and computer simulations. Data collected at 50, 70, 90 110 rpm during stationary cycling were used to drive musculoskeletal modelling simulation and estimate muscle-tendon length. Results demonstrated that BCoM trajectory, confined in a 15-mm side cube, changed its orientation, maintaining a similar pattern across all cadences in both bicycles. RB displayed a reduced additional mechanical external power (16.1 ± 9.7 W on RB vs. 20.3 ± 8.8 W on NB), a greater symmetry on the progression axis, and no differences in the internal mechanical power compared to NB. Simulated muscle activity revealed small significant differences for only selected muscles. On the RB, quadriceps and gluteus demonstrated greater shortening, while biceps femoris, iliacus, and psoas exhibited greater stretch; however, aerodynamics still remains the principal benefit.

  13. Effect of antagonist muscle fatigue on knee extension torque.

    PubMed

    Beltman, J G M; Sargeant, A J; Ball, D; Maganaris, C N; de Haan, A

    2003-09-01

    The effect of hamstring fatigue on knee extension torque was examined at different knee angles for seven male subjects. Before and after a dynamic flexion fatigue protocol (180 degrees s(-1), until dynamic torque had declined by 50%), maximal voluntary contraction extension torque was measured at four knee flexion angles (90 degrees, 70 degrees, 50 degrees and 30 degrees ). Maximal torque generating capacity and voluntary activation of the quadriceps muscle were determined using electrical stimulation. Average rectified EMG of the biceps femoris was determined. Mean dynamic flexion torque declined by 48+/-11%. Extensor maximal voluntary contraction torque, maximal torque generating capacity, voluntary activation and average rectified EMG at the four knee angles were unaffected by the hamstring fatigue protocol. Only at 50 degrees knee angle was voluntary activation significantly lower (15.7%) after fatigue ( P<0.05). In addition, average rectified EMG before fatigue was not significantly influenced by knee angle. It was concluded that a fatigued hamstring muscle did not increase the maximal voluntary contraction extension torque and knee angle did not change coactivation. Three possible mechanisms may explain the results: a potential difference in recruited fibre populations in antagonist activity compared with the fibres which were fatigued in the protocol, a smaller loss in isometric torque generating capacity of the hamstring muscle than was expected from the dynamic measurements and/or a reduction in voluntary activation.

  14. Proteolysis and sensory properties of dry-cured bacon as affected by the partial substitution of sodium chloride with potassium chloride.

    PubMed

    Wu, Haizhou; Zhang, Yingyang; Long, Men; Tang, Jing; Yu, Xiang; Wang, Jiamei; Zhang, Jianhao

    2014-03-01

    Quadriceps femoris muscle samples (48) from 24 pigs were processed into dry-cured bacon. This study investigated the influence of partial substitution of sodium chloride (NaCl) with potassium chloride (KCl) on proteolysis and sensory properties of dry-cured bacon. Three salt treatments were considered, namely, I (100% NaCl), II (60% NaCl, 40% KCl), and III (30% NaCl, 70% KCl). No significant differences were observed among treatments in the proteolysis, which was reflected by SDS-PAGE, proteolysis index, amino acid nitrogen, and peptide nitrogen contents. Furthermore, there were no significant differences in the moisture content between control and treatment II, whereas the moisture content in treatment III was significantly higher (p<0.05) in comparison with control (treatment I). The sensory analysis indicated that it was possible to reduce NaCl by 40% without adverse effects on sensory properties, but 70% replacement of NaCl with KCl resulted in bacon with less hardness and saltiness and higher (p<0.05) juiciness and bitterness.

  15. Neuromuscular Electrical Stimulation Versus Volitional Isometric Strength Training in Children With Spastic Diplegic Cerebral Palsy: A Preliminary Study

    PubMed Central

    Stackhouse, Scott K.; Binder-Macleod, Stuart A.; Stackhouse, Carrie A.; McCarthy, James J.; Prosser, Laura A.; Lee, Samuel C. K.

    2011-01-01

    Background To date, no reports have investigated neuromuscular electrical stimulation (NMES) to increase muscle force production of children with cerebral palsy (CP) using high-force contractions and low repetitions. Objective The aims of this study were to determine if isometric NMES or volitional training in children with CP could increase muscle strength and walking speed and to examine the mechanisms that may contribute to increased force production. Methods Eleven children with spastic diplegia were assigned to an NMES training group or to a volitional training group. Participants in the NMES group had electrodes implanted percutaneously to activate the quadriceps femoris and triceps surae muscles. The volitional group trained with maximal effort contractions. Both groups performed a 12-week isometric strength-training program. Maximum voluntary isometric contract ion (MVIC) force, voluntary muscle activation, quadriceps and triceps surae cross-sectional area (CSA), and walking speed were measured pre- and post-strength training. Results The NMES-trained group had greater increases in normalized force production for both die quadriceps femoris and triceps surae. Similarly only the NMES group showed an increase in walking speed after training. Changes in voluntary muscle activation explained approximately 67% and 37% of the changes seen in the MVIC of the NMES and volitional groups, respectively. Quadriceps femoris maximum CSA increased significantly for the NMES group only. Conclusions This study was the first to quantitatively show strength gains with the use of NMES in children with CP. These results support the need for future experimental studies that will examine the clinical effectiveness of NMES strength training. PMID:17369515

  16. Muscle Activation Patterns During Different Squat Techniques.

    PubMed

    Slater, Lindsay V; Hart, Joseph M

    2017-03-01

    Slater, LV, and Hart, JM. Muscle activation patterns during different squat techniques. J Strength Cond Res 31(3): 667-676, 2017-Bilateral squats are frequently used exercises in sport performance programs. Lower extremity muscle activation may change based on knee alignment during the performance of the exercise. The purpose of this study was to compare lower extremity muscle activation patterns during different squat techniques. Twenty-eight healthy, uninjured subjects (19 women, 9 men, 21.5 ± 3 years, 170 ± 8.4 cm, 65.7 ± 11.8 kg) volunteered. Electromyography (EMG) electrodes were placed on the vastus lateralis, vastus medialis, rectus femoris, biceps femoris, and the gastrocnemius of the dominant leg. Participants completed 5 squats while purposefully displacing the knee anteriorly (AP malaligned), 5 squats while purposefully displacing the knee medially (ML malaligned) and 5 squats with control alignment (control). Normalized EMG data (MVIC) were reduced to 100 points and represented as percentage of squat cycle with 50% representing peak knee flexion and 0 and 99% representing fully extended. Vastus lateralis, medialis, and rectus femoris activity decreased in the medio-lateral (ML) malaligned squat compared with the control squat. In the antero-posterior (AP) malaligned squat, the vastus lateralis, medialis, and rectus femoris activity decreased during initial descent and final ascent; however, vastus lateralis and rectus femoris activation increased during initial ascent compared with the control squat. The biceps femoris and gastrocnemius displayed increased activation during both malaligned squats compared with the control squat. In conclusion, participants had altered muscle activation patterns during squats with intentional frontal and sagittal malalignment as demonstrated by changes in quadriceps, biceps femoris, and gastrocnemius activation during the squat cycle.

  17. Influence Operations in Afghanistan

    DTIC Science & Technology

    2006-10-06

    strong central government and marginalizing the influence of radical religious groups who either engage in or support attacks on central government...decision makers are, who they trust, how resolute or tenacious a group is and how open to change a group is. Any Influence Operation must take these...as well as how each group perceives and interacts with other groups is pertinent to developing an effective Influence Operations plan. Pashtun

  18. Link Influence Entropy

    NASA Astrophysics Data System (ADS)

    Singh, Priti; Chakraborty, Abhishek; Manoj, B. S.

    2017-01-01

    In this paper we propose a new metric, Link Influence Entropy (LInE), which describes importance of each node based on the influence of each link present in a network. Influence of a link can neither be effectively estimated using betweenness centrality nor using degree based probability measures. The proposed LInE metric which provides an effective way to estimate the influence of a link in the network and incorporates this influence to identify nodal characteristics, performs better compared to degree based entropy. We found that LInE can differentiate various network types which degree-based or betweenness centrality based node influence metrics cannot. Our findings show that spatial wireless networks and regular grid networks, respectively, have lowest and highest LInE values. Finally, performance analysis of LInE is carried out on a real-world network as well as on a wireless mesh network testbed to study the influence of our metric as well as influence stability of nodes in dynamic networks.

  19. Influencing Your Colleagues.

    ERIC Educational Resources Information Center

    Walker, Alice D.

    1993-01-01

    This fifteenth article in a series on the principles of the AECT (Association for Educational Communications and Technology) Code of Professional Ethics focuses on members using coercive means to influence decisions of colleagues, using an example of a professor trying to influence a colleague to include his name on a research proposal. (LRW)

  20. Factors Influencing Army Maintenance

    DTIC Science & Technology

    1989-01-01

    ARI Research Note 89-11 (N 00 Factors Influencing Army Maintenance LOloD Debra C. Evans and J. Thomas Roth Applied Science Associates, Inc. for...1.2.7 .2.7.C.1 11. TITLE (Include Security ClassifIcarIon) Factors Influencing Army Maintenance i2. FERSONAL AuTtiOR(S) Evans, Debra C., and Roth, J...y • ’ Factors and variables that influence maintenance for systems and related manpower, per- sonnel, and training (MPT) characteristics were

  1. [Natural factors influencing sleep].

    PubMed

    Jurkowski, Marek K; Bobek-Billewicz, Barbara

    2007-01-01

    Sleep is a universal phenomenon of human and animal lives, although the importance of sleep for homeo-stasis is still unknown. Sleep disturbances influence many behavioral and physiologic processes, leading to health complications including death. On the other hand, sleep improvement can beneficially influence the course of healing of many disorders and can be a prognostic of health recovery. The factors influencing sleep have different biological and chemical origins. They are classical hormones, hypothalamic releasing and inhibitory hormones, neuropeptides, peptides and others as cytokines, prostaglandins, oleamid, adenosine, nitric oxide. These factors regulate most physiologic processes and are likely elements integrating sleep with physiology and physiology with sleep in health and disorders.

  2. Status, Numbers and Influence

    ERIC Educational Resources Information Center

    Melamed, David; Savage, Scott V.

    2013-01-01

    We develop a theoretical model of social influence in n-person groups. We argue that disagreement between group members introduces uncertainty into the social situation, and this uncertainty motivates people to use status characteristics to evaluate the merits of a particular opinion. Our model takes the numerical distribution of opinions and the…

  3. Tactics of Social Influence.

    ERIC Educational Resources Information Center

    Mehrabian, Albert

    In this book, the principles of behavior modification are presented as a set of guidelines for identifying recurrent behavior patterns and are then applied as techniques to change various undesirable behaviors. Progressively more complex steps toward behavior modification and its social influence are cited and illustrated in chapters which deal…

  4. Sex Differences in Influenceability

    ERIC Educational Resources Information Center

    Eagly, Alice H.

    1978-01-01

    Examines the hypothesis that women are more easily influenced than men by reviewing the literature on persuasion and conformity research. Persuasion research and conformity studies not involving group pressure show scant empirical support for sex differences. For group pressure conformity research, a substantial minority of studies support the…

  5. The Drive to Influence

    ERIC Educational Resources Information Center

    Rodriguez, Diego

    2017-01-01

    At the heart of the educational vocation is a drive to influence, to meaningfully affect the learning and development of others. For adult educators working in higher education, daily activities--from teaching classes to supervising student research to attending faculty meetings to sitting on advisory boards--are full of opportunities to…

  6. Activation of back and lower limb muscles during squat exercises with different trunk flexion

    PubMed Central

    Lee, Tae-Sik; Song, Min-Young; Kwon, Yu-Jeong

    2016-01-01

    [Purpose] The purpose of this study was to investigate the activation of back and lower limb muscles in subjects who were performing a squat exercise at different angles of trunk flexion. [Subjects and Methods] Twenty healthy subjects (age 21.1± 1.8 years, height 168.7 ± 8.2 cm, weight 66.1 ± 12.3 kg) volunteered. The activation of the erector spinae muscle, rectus femoris muscle, gluteus maximus muscle and biceps femoris muscle was observed while the subjects performed squat exercises with a trunk flexion of 0°, 15°, and 30°. [Results] The erector spinae muscle, gluteus maximus muscle, and biceps femoris muscle were activated more during the squat exercise with the trunk flexion at 30° than the exercise with the trunk flexion at 0°. The rectus femoris muscle showed a tendency to decrease as the truck flexion increased. [Conclusion] Squat exercise be executed while maintaining an erect trunk posture if one wishes to strengthen the quadriceps muscle while reducing the load on the lower back. PMID:28174462

  7. Activation of back and lower limb muscles during squat exercises with different trunk flexion.

    PubMed

    Lee, Tae-Sik; Song, Min-Young; Kwon, Yu-Jeong

    2016-12-01

    [Purpose] The purpose of this study was to investigate the activation of back and lower limb muscles in subjects who were performing a squat exercise at different angles of trunk flexion. [Subjects and Methods] Twenty healthy subjects (age 21.1± 1.8 years, height 168.7 ± 8.2 cm, weight 66.1 ± 12.3 kg) volunteered. The activation of the erector spinae muscle, rectus femoris muscle, gluteus maximus muscle and biceps femoris muscle was observed while the subjects performed squat exercises with a trunk flexion of 0°, 15°, and 30°. [Results] The erector spinae muscle, gluteus maximus muscle, and biceps femoris muscle were activated more during the squat exercise with the trunk flexion at 30° than the exercise with the trunk flexion at 0°. The rectus femoris muscle showed a tendency to decrease as the truck flexion increased. [Conclusion] Squat exercise be executed while maintaining an erect trunk posture if one wishes to strengthen the quadriceps muscle while reducing the load on the lower back.

  8. Delayed Femoral Nerve Palsy Associated with Iliopsoas Hematoma after Primary Total Hip Arthroplasty

    PubMed Central

    Kumar, Sandeep

    2016-01-01

    Femoral nerve neuropathy after total hip arthroplasty is rare but catastrophic complication. Pain and quadriceps muscle weakness caused by this complication can significantly affect the functional outcome. Here we present a case report, describing delayed onset femoral nerve palsy associated with iliopsoas hematoma following pseudoaneurysm of a branch of profunda femoris artery after 3 months of primary total hip arthroplasty in an 80-year-old female patient with single kidney. Hip arthroplasty was done for painful primary osteoarthritis of left hip. Diagnosis of femoral nerve palsy was made by clinical examination and computed tomography imaging of pelvis. Patient was managed by surgical evacuation of hematoma and physiotherapy. The patient's clinical symptoms were improved after surgical evacuation of hematoma. This is the first case report of its kind in English literature regarding delayed onset femoral nerve palsy after primary total hip arthroplasty due to pseudoaneurysm of a branch of profunda femoris artery without any obvious precipitating factor. PMID:27752378

  9. Influence plots for LASSO

    SciTech Connect

    Jang, Dae -Heung; Anderson-Cook, Christine Michaela

    2016-11-22

    With many predictors in regression, fitting the full model can induce multicollinearity problems. Least Absolute Shrinkage and Selection Operation (LASSO) is useful when the effects of many explanatory variables are sparse in a high-dimensional dataset. Influential points can have a disproportionate impact on the estimated values of model parameters. Here, this paper describes a new influence plot that can be used to increase understanding of the contributions of individual observations and the robustness of results. This can serve as a complement to other regression diagnostics techniques in the LASSO regression setting. Using this influence plot, we can find influential points and their impact on shrinkage of model parameters and model selection. Lastly, we provide two examples to illustrate the methods.

  10. Influence plots for LASSO

    DOE PAGES

    Jang, Dae -Heung; Anderson-Cook, Christine Michaela

    2016-11-22

    With many predictors in regression, fitting the full model can induce multicollinearity problems. Least Absolute Shrinkage and Selection Operation (LASSO) is useful when the effects of many explanatory variables are sparse in a high-dimensional dataset. Influential points can have a disproportionate impact on the estimated values of model parameters. Here, this paper describes a new influence plot that can be used to increase understanding of the contributions of individual observations and the robustness of results. This can serve as a complement to other regression diagnostics techniques in the LASSO regression setting. Using this influence plot, we can find influential pointsmore » and their impact on shrinkage of model parameters and model selection. Lastly, we provide two examples to illustrate the methods.« less

  11. Influences of physical fitness on bone mass in women with fibromyalgia.

    PubMed

    Gómez-Cabello, Alba; Vicente-Rodríguez, Germán; Navarro-Vera, Isabel; Martinez-Redondo, Diana; Díez-Sánchez, Carmen; Casajús, José Antonio

    2015-04-01

    The aim of this study was to provide information about the relationship of bone mineral content (BMC) and density (BMD) with some physical-fitness-related variables in a sample of women with fibromyalgia (FM) and age-matched women without FM. Twenty-eight women clinically diagnosed with FM (age 51.1 ± 8.4 yr, M ± SD) and 22 age-matched controls participated in the study. Whole-body BMC and BMD, lean mass, handgrip strength, quadriceps strength, and cardiovascular fitness were measured in all participants. The association between physical-fitness variables and bone-related variables was tested by linear regression controlling for body weight as a possible confounder. There were no differences in BMC or BMD between groups. Women with FM had lower values of handgrip strength, quadriceps strength, and VO2peak than the control group. Handgrip strength and aerobic capacity were associated with BMC and BMD and quadriceps strength was associated with BMD in women with FM; however, only VO2peak was associated with BMC in the group of women without FM. Bone mass of women with FM may be more susceptible to changes in physical fitness than that of the women without fibromyalgia.

  12. Microbiologically Influenced Corrosion

    DTIC Science & Technology

    2009-01-01

    Japan, Australia, and Germany estimate the cost of corro- sion to be 1-5% of the gross national product (2). Microbiologically influenced...in each dimen- sion than bacteria and archaea. Fungi are eukaryotic organisms. Yeasts, molds, and mushrooms are examples of fungi. The majority of...Bacteria within biofilms, use waste products generated by other bacteria as nutrients that are metabolized to fatty acids, carbon dioxide and

  13. Trust and Influence

    DTIC Science & Technology

    2013-03-06

    how humans establish, maintain, and repair trust of humans and technological systems) and the science of influence (i.e., understanding how to shape...factors that shape reliance in complex human -machine interactions • Cross-Cultural Trust – identify the antecedents of trust in different cultures...actions of others with little ability to monitor their actions (Mayer et al., 1995) Assumptions: •Trust as a human phenomenon •Trust

  14. Real-time noninvasive optical imaging of exercising muscle and brain upon cognitive stimuli

    NASA Astrophysics Data System (ADS)

    Quaresima, Valentina; van der Sluijs, Marco C.; Menssen, Jan; Grillotti, Lucia; Ferrari, Marco; Colier, Willy N.

    2001-06-01

    The monitoring of a single muscle location does not reflect the heterogeneity of the muscle groups activation during exercise. In the past, measurements of oxygen consumption (VO2) at single muscle locations could be carried out non-invasively by near-infrared continuous wave spectroscopy (NIRCWS) at rest or during isometric contractions. In the present study, human regional quadriceps (vastus lateralis and rectus femoris) VO2 was investigated at rest and during maximal voluntary contractions using a 12- channel NIRCWS system with an acquisition time of 0.1 s.

  15. Diffusion Influenced Adsorption Kinetics.

    PubMed

    Miura, Toshiaki; Seki, Kazuhiko

    2015-08-27

    When the kinetics of adsorption is influenced by the diffusive flow of solutes, the solute concentration at the surface is influenced by the surface coverage of solutes, which is given by the Langmuir-Hinshelwood adsorption equation. The diffusion equation with the boundary condition given by the Langmuir-Hinshelwood adsorption equation leads to the nonlinear integro-differential equation for the surface coverage. In this paper, we solved the nonlinear integro-differential equation using the Grünwald-Letnikov formula developed to solve fractional kinetics. Guided by the numerical results, analytical expressions for the upper and lower bounds of the exact numerical results were obtained. The upper and lower bounds were close to the exact numerical results in the diffusion- and reaction-controlled limits, respectively. We examined the validity of the two simple analytical expressions obtained in the diffusion-controlled limit. The results were generalized to include the effect of dispersive diffusion. We also investigated the effect of molecular rearrangement of anisotropic molecules on surface coverage.

  16. Vehicular road influence areas

    NASA Astrophysics Data System (ADS)

    Huertas, María E.; Huertas, José I.; Valencia, Alexander

    2017-02-01

    Vehicle operation over paved and unpaved roads is an emission source that significantly contributes to air pollution. Emissions are derived from vehicle exhaust pipes and re-suspension of particulate matter generated by wind erosion and tire to road surface interactions. Environmental authorities require a methodology to evaluate road impact areas, which enable managers to initiate counter-measures, particularly under circumstances where historic meteorological and/or air quality data is unavailable. The present study describes an analytical and experimental work developed to establish a simplified methodology to estimate the area influenced by vehicular roads. AERMOD was chosen to model pollutant dispersion generated by two roads of common attributes (straight road over flat terrain) under the effects of several arbitrary chosen weather conditions. The resulting pollutant concentration vs. Distance curves collapsed into a single curve when concentration and distance were expressed as dimensionless numbers and this curve can be described by a beta distribution function. This result implied that average concentration at a given distance was proportional to emission intensity and that it showed minor sensitivity to meteorological conditions. Therefore, road influence was defined by the area adjacent to the road limited by distance at which the beta distribution function equaled the limiting value specified by the national air quality standard for the pollutant under consideration.

  17. Effect of Exercise-Induced Enhancement of the Leg-Extensor Muscle-Tendon Unit Capacities on Ambulatory Mechanics and Knee Osteoarthritis Markers in the Elderly

    PubMed Central

    Karamanidis, Kiros; Oberländer, Kai Daniel; Niehoff, Anja; Epro, Gaspar; Brüggemann, Gert-Peter

    2014-01-01

    Objective Leg-extensor muscle weakness could be a key component in knee joint degeneration in the elderly because it may result in altered muscular control during locomotion influencing the mechanical environment within the joint. This work aimed to examine whether an exercise-induced enhancement of the triceps surae (TS) and quadriceps femoris (QF) muscle-tendon unit (MTU) capacities would affect mechanical and biological markers for knee osteoarthritis in the elderly. Methods Twelve older women completed a 14-week TS and QF MTU exercise intervention, which had already been established as increasing muscle strength and tendon stiffness. Locomotion mechanics and serum cartilage oligomeric matrix protein (COMP) levels were examined during incline walking. MTU mechanical properties were assessed using simultaneously ultrasonography and dynamometry. Results Post exercise intervention, the elderly had higher TS and QF contractile strength and tendon-aponeurosis stiffness. Regarding the incline gait task, the subjects demonstrated a lower external knee adduction moment and lower knee adduction angular impulse during the stance phase post-intervention. Furthermore, post-intervention compared to pre-intervention, the elderly showed lower external hip adduction moment, but revealed higher plantarflexion pushoff moment. The changes in the external knee adduction moment were significantly correlated with the improvement in ankle pushoff function. Serum COMP concentration increased in response to the 0.5-h incline walking exercise with no differences in the magnitude of increment between pre- and post-intervention. Conclusions This work emphasizes the important role played by the ankle pushoff function in knee joint mechanical loading during locomotion, and may justify the inclusion of the TS MTU in prevention programs aiming to positively influence specific mechanical markers for knee osteoarthritis in the elderly. However, the study was unable to show that COMP is amenable

  18. Mechanics of the muscles crossing the hip joint during sprint running.

    PubMed

    Nagano, Yasuharu; Higashihara, Ayako; Takahashi, Kazumasa; Fukubayashi, Toru

    2014-01-01

    We aimed to demonstrate the changes over time in the lengths and forces of the muscles crossing the hip joint during overground sprinting and investigate the relationships between muscle lengths and muscle-tendon unit forces - particularly peak biceps femoris force. We obtained three-dimensional kinematics during 1 running cycle from 8 healthy sprinters sprinting at maximum speed. Muscle lengths and muscle-tendon unit forces were calculated for the iliacus, rectus femoris, gluteus maximus, and biceps femoris muscles of the target leg as well as the contralateral iliacus and rectus femoris. Our results showed that during sprinting, the muscles crossing the hip joint demonstrate a stretch-shortening cycle and 1 or 2 peak forces. The timing of peak biceps femoris force, expressed as a percentage of the running cycle (mean [SD], 80.5 [2.9]%), was synchronous with those of the maximum biceps femoris length (82.8 [1.9]%) and peak forces of the gluteus maximus (83.8 [9.1]%), iliacus (81.1 [5.2]%), and contralateral iliacus (78.5 [5.8]%) and also that of the peak pelvic anterior tilt. The force of the biceps femoris appeared to be influenced by the actions of the muscles crossing the hip joint as well as by the pelvic anterior tilt.

  19. Influences on assortative mating.

    PubMed

    Schmidt, H D; Glavce, C; Hartog, J

    1987-09-01

    Age plays a considerable role in assortative mating. As regards this criterion we can distinguish a "rural, more traditional model" with high values of the coefficients of correlation, and an "urban model" with significantly lower values. Concerning eye and hair colour we find both these models as well as transitional forms. In contrast to this there are no important differences in assortative mating between the rural and urban populations regarding the physical traits. Size of population and length of marriage can strongly influence the values of these correlations. They decrease as the size of the population decreases, in which a person chooses his/her partner. Increasing age of the couples also results in a decrease of these correlations.

  20. Developing Global Nurse Influencers.

    PubMed

    Spies, Lori A

    2016-01-01

    How can universities create engaged citizens and global leaders? Each year, a select group of advanced practice nursing students at Baylor University Louise Herrington School of Nursing travel to Africa for a month-long clinical mission experience. Students work alongside local and missionary healthcare providers in a comprehensive Christian outreach to the community at a high-volume clinic. Creating rich learning experiences in a global setting in significant and sustainable ways is difficult, but intentionally focusing on what we are called to do and who we serve provides ballast for faculty and students. The success of the trip in preparing students to be global influencers is evident by the work graduates elect to do around the world, following graduation.

  1. MEMS electrostatic influence machines

    NASA Astrophysics Data System (ADS)

    Phu Le, Cuong; Halvorsen, Einar

    2016-11-01

    This paper analyses the possibility of MEMS electrostatic influence machines using electromechanical switches like the historical predecessors did two centuries ago. We find that a generator design relying entirely on standard silicon-on-insulator(SOI) micromachining is conceivable and analyze its performance by simulations. The concept appears preferable over comparable diode circuits due to its higher maximum energy, faster charging and low precharging voltage. A full electromechanical lumped-model including parasitic capacitances of the switches is built to capture the dynamic of the generator. Simulation results show that the output voltage can be exponentially bootstrapped from a very low precharging voltage so that otherwise inadequately small voltage differences or charge imbalances can be made useful.

  2. Neuro-mechanical determinants of repeated treadmill sprints - Usefulness of an “hypoxic to normoxic recovery” approach

    PubMed Central

    Girard, Olivier; Brocherie, Franck; Morin, Jean-Benoit; Millet, Grégoire P.

    2015-01-01

    To improve our understanding of the limiting factors during repeated sprinting, we manipulated hypoxia severity during an initial set and examined the effects on performance and associated neuro-mechanical alterations during a subsequent set performed in normoxia. On separate days, 13 active males performed eight 5-s sprints (recovery = 25 s) on an instrumented treadmill in either normoxia near sea-level (SL; FiO2 = 20.9%), moderate (MH; FiO2 = 16.8%) or severe normobaric hypoxia (SH; FiO2 = 13.3%) followed, 6 min later, by four 5-s sprints (recovery = 25 s) in normoxia. Throughout the first set, along with distance covered [larger sprint decrement score in SH (−8.2%) compared to SL (−5.3%) and MH (−7.2%); P < 0.05], changes in contact time, step frequency and root mean square activity (surface electromyography) of the quadriceps (Rectus femoris muscle) in SH exceeded those in SL and MH (P < 0.05). During first sprint of the subsequent normoxic set, the distance covered (99.6, 96.4, and 98.3% of sprint 1 in SL, MH, and SH, respectively), the main kinetic (mean vertical, horizontal, and resultant forces) and kinematic (contact time and step frequency) variables as well as surface electromyogram of quadriceps and plantar flexor muscles were fully recovered, with no significant difference between conditions. Despite differing hypoxic severity levels during sprints 1–8, performance and neuro-mechanical patterns did not differ during the four sprints of the second set performed in normoxia. In summary, under the circumstances of this study (participant background, exercise-to-rest ratio, hypoxia exposure), sprint mechanical performance and neural alterations were largely influenced by the hypoxia severity in an initial set of repeated sprints. However, hypoxia had no residual effect during a subsequent set performed in normoxia. Hence, the recovery of performance and associated neuro-mechanical alterations was complete after resting for 6 min near sea level

  3. Microstructural influences on the

    NASA Astrophysics Data System (ADS)

    Ramesh, K. T.; Coates, R. S.

    1992-09-01

    The influence of tungsten content, swaging, and grain size on the dynamic behavior of commercially available tungsten-nickel-iron (W-Ni-Fe) alloys has been examined using the compression Kolsky bar. The observed flow stresses increase with increasing tungsten content and with degree of swaging but are essentially independent of grain size for these compressive deformations. Further, the flow stresses sustained by these materials have a distinct dependence on strain rate, in that the flow stress increases by at least 20 pct over a range from 10-4 s-1 to 7 × 103 s-1. The rate sensitivity itself increases with increasing tungsten content. The rate sensitivity of the alloy with the highest tungsten content (97 pct W) appears to be essentially the same as that of pure polycrystalline tungsten. In addition to showing greater strain hardening, the unswaged alloy also shows a much higher rate dependence than the swaged alloys, with the flow stress almost doubling when the rate of deformation increases from quasistatic to 5 X 103 s-1. The rate-hardening mechanism within the composite appears to be essentially that as- sociated with the tungsten grains; however, the matrix contribution is significant in the case of an unswaged alloy.

  4. Genetic influences on sarcoidosis.

    PubMed

    Ishihara, M; Ohno, S

    1997-01-01

    To investigate the genetic influences underlying the development of sarcoidosis, HLA class II genotyping was performed in Japanese patients with sarcoidosis and healthy controls using the PCR-RFLP method. The frequencies of both DR52 group antigen-associated alleles (HLA-DRB1*11, -DRB1*12 and -DRB1*14) and DRB1*08 alleles were higher in the patient group, suggesting that the common, specific amino acid residue on the DRB1 molecule of these alleles may determine susceptibility to sarcoidosis. Alternatively, it is possible that another susceptibility gene, linked to these DRB1 alleles, exists within the MHC region. We screened the TNFA, TNFB, HSP70-1 and Hum70t genes around the class III region, as well as the HLA-DMA and -DMB genes in the class II region, for genetic polymorphism in sarcoidosis. None of these genes suggested a susceptibility to sarcoidosis. These studies support the thesis that one of the major genetic factors controlling the development of sarcoidosis is located within the DRB1 locus in the HLA class II region.

  5. How experts gain influence.

    PubMed

    Mikes, Anette; Hall, Matthew; Millo, Yuval

    2013-01-01

    In theory, the risk management groups of two British banks--Saxon and Anglo--had the same influence in their organizations. But in practice, they did not: Saxon's was engaged in critical work throughout the bank, while Anglo's had little visibility outside its areas of expertise. In their study of these two financial institutions, the authors identified four competencies--trailblazing, toolmaking, teamwork, and translation--that help functional leaders or groups compete for top management's limited attention and increase their impact. Anglo's risk managers were strong in only some of the competencies, but Saxon's were strong in all four. They consistently scanned the internal and external environment for important issues to which they could apply a risk management perspective (trailblazing) and then developed tools--such as quarterly risk reports--that spread their expertise (toolmaking). While controlling the tools' design and implementation, the risk managers incorporated business managers' insights (teamwork) and made sure everyone could understand the findings (translation). Ultimately, experts' roles must fit the organization's strategy and structural needs. In some situations, functional experts can raise their profile by cultivating just two of the competencies. But those who are strong in all four are likely to be the most influential.

  6. The effect of squat depth on multiarticular muscle activation in collegiate cross-country runners.

    PubMed

    Gorsuch, Joshua; Long, Janey; Miller, Katie; Primeau, Kyle; Rutledge, Sarah; Sossong, Andrew; Durocher, John J

    2013-09-01

    The squat is a closed-chain lower body exercise commonly performed by many athletes. Muscle activity has been examined during partial and parallel squats in male weightlifters, but not in male and female runners. Therefore, this study measured muscle activity with surface electromyography (EMG) during partial and parallel squats in 20 Division I collegiate cross-country runners (10 males and 10 females) in a randomized crossover design. We hypothesized the parallel squat would increase extensor muscle activitation (i.e. hamstrings and erector spinae). Furthermore, we sought to determine if changes in muscle activity were different between males and females. Participants performed 6 repetitions using their 10 repetition maximum loads for each condition during EMG testing. EMG was performed on the right rectus femoris, biceps femoris, lumbar erector spinae, and lateral head of the gastrocnemius. Rectus femoris activity (0.18 ± 0.01 vs. 0.14 ± 0.01 mV) and erector spinae activity (0.16 ± 0.01 vs. 0.13 ± 0.01 mV) were significantly higher (p < 0.05) during the parallel squat than during the partial squat condition. This increase in muscle activity may be attributed to greater ranges of motion at the hip and knee joints. Biceps femoris and gastrocnemius activity were similar between conditions. No significant differences existed between males and females (squat condition × gender; p > 0.05). During preliminary isokinetic testing, both male and female runners demonstrated deficient hamstrings-to-quadriceps ratios, which would not likely improve by performing parallel squats based on our EMG findings. Despite the reduced load of the parallel squat, rectus femoris and erector spinae activity were elevated. Thus, parallel squats may help runners to train muscles vital for uphill running and correct posture, while preventing injury by using lighter weights through a larger range of motion.

  7. Power, Influence Tactics, and Influence Processes in Virtual Teams

    ERIC Educational Resources Information Center

    Boughton, Marla

    2011-01-01

    Current studies of power, influence tactics, and influence processes in virtual teams assume that these constructs operate in a similar manner as they do in the face-to-face (FtF) environment. However, the virtual context differs from the FtF environment on a variety of dimensions, such as the availability of status cues. The differences between…

  8. Nutritional influences during pregnancy.

    PubMed

    Pitkin, R M

    1977-01-01

    Maternal nutrition represents one of the important influences on the course and outcome of pregnancy and attention to nutritional factors (i.e., assessment of nutritional status, dietary advice, and follow-up evaluation) properly constitute an essential component of prenatal care. Nearly all nutrients are required in increased amounts during gestation but the magnitude of the increase varies from nutrient to nutrient. Caloric needs increase by 300 kcal per day, representing an addition of 15 per cent, and should be sufficient to support a weight gain averaging 350 to 400 gm per week during the last two trimesters. Total protein intake during pregnancy should be 1.3 gm per kg for the mature woman and somewhat higher for the adolescent. Gestational needs for iron cannot be met by diet and supplementation (in the form of simple ferrous salts, 30 to 60 mg daily) should be provided. Folate requirements are doubled during pregnancy and, while these can be met by diet, supplementation may be considered as an option. Provision of the gestational calcium allowance from food sources is readily possible if (and only if) daily products are consumed. The generally increased need for other nutrients can be provided readily by the properly selected diet. Thus, with respect to supplements, iron and perhaps folate should be advised routinely while other vitamin-mineral supplements are probably neither helpful nor harmful. Prescription of vitamin-mineral supplements cannot be expected to compensate for poor dietary habits. Dietary restriction of nutrients in general, and energy and sodium in particular, has the potential for impairing the maternal capacity to make the required physiologic adjustments of pregnancy and interfering with fetal development. Restriction of any nutrient to levels below the guidelines provided by the Recommended Dietary Allowances is rarely if ever advisable.

  9. Text Signals Influence Team Artifacts

    ERIC Educational Resources Information Center

    Clariana, Roy B.; Rysavy, Monica D.; Taricani, Ellen

    2015-01-01

    This exploratory quasi-experimental investigation describes the influence of text signals on team visual map artifacts. In two course sections, four-member teams were given one of two print-based text passage versions on the course-related topic "Social influence in groups" downloaded from Wikipedia; this text had two paragraphs, each…

  10. Curbing Cartel Influence in Mexico

    DTIC Science & Technology

    2011-10-28

    Mexico back from achieving its potential in the global market place. Cartel influence hampers legitimate business competition. Violence, combined...system is holding Mexico back from achieving its potential in the global market place. Cartel influence hampers legitimate business competition...east and west coast organizations. However, cartel allegiances are for business first, as they share risks and markets only to protect profits.20

  11. Student Influence and Higher Education.

    ERIC Educational Resources Information Center

    Juola, Arvo E.

    Since 1965, student views and feelings have influenced great changes in higher education, sometimes to the detriment of long-term interests in academic institutions and colleges. One conspicuous recent trend is the desire of college students for more influence, impact, or power. Other prevalent attitudes may be characterized as a desire to be…

  12. Lunar Influences on Human Aggression.

    ERIC Educational Resources Information Center

    Russell, Gordon W.; Dua, Manjula

    1983-01-01

    Used league records of all Canadian hockey games (N=426) played during a season to test a lunar-aggression hypothesis. Despite the use of multiple measures of lunar phase and interpersonal aggression, support for lunar influence was not forthcoming. Supplemental data revealed that beliefs in lunar influence are fairly common. (JAC)

  13. Wetland Research Can Influence Policy

    EPA Science Inventory

    An objective of ecological research is to have a positive influence on the way natural resources are managed. The ability to influence policy with science depends on collaboration with the appropriate audience, identification of a relevant question, and awareness of the framewor...

  14. Inhibition of α-adrenergic tone disturbs the distribution of blood flow in the exercising human limb.

    PubMed

    Heinonen, Ilkka; Wendelin-Saarenhovi, Maria; Kaskinoro, Kimmo; Knuuti, Juhani; Scheinin, Mika; Kalliokoski, Kari K

    2013-07-15

    The role of neuronal regulation of human cardiovascular function remains incompletely elucidated, especially during exercise. Here we, by positron emission tomography, monitored tissue-specific blood flow (BF) changes in nine healthy young men during femoral arterial infusions of norepinephrine (NE) and phentolamine. At rest, the α-adrenoceptor agonist NE reduced BF by ~40%, similarly in muscles (from 3.2 ± 1.9 to 1.4 ± 0.3 ml·min(-1)·100 g(-1) in quadriceps femoris muscle), bone (from 1.1 ± 0.4 to 0.5 ± 0.2 ml·min(-1)·100 g(-1)) and adipose tissue (AT) (from 1.2 ± 0.7 to 0.7 ± 0.3 ml·min(-1)·100 g(-1)). During exercise, NE reduced exercising muscle BF by ~16%. BF in AT was reduced similarly as rest. The α-adrenoceptor antagonist phentolamine increased BF similarly in the different muscles and other tissues of the limb at rest. During exercise, BF in inactive muscle was increased 3.4-fold by phentolamine compared with exercise without drug, but BF in exercising muscles was not influenced. Bone and AT (P = 0.055) BF were also increased by phentolamine in the exercise condition. NE increased and phentolamine decreased oxygen extraction in the limb during exercise. We conclude that inhibition of α-adrenergic tone markedly disturbs the distribution of BF and oxygen extraction in the exercising human limb by increasing BF especially around inactive muscle fibers. Moreover, although marked functional sympatholysis also occurs during exercise, the arterial NE infusion that mimics the exaggerated sympathetic nerve activity commonly seen in patients with cardiovascular disease was still capable of directly limiting BF in the exercising leg muscles.

  15. Effect of different feeds on meat quality and fatty acid composition of lambs fattened at pasture.

    PubMed

    Velasco, S; Cañeque, V; Lauzurica, S; Pérez, C; Huidobro, F

    2004-02-01

    Two kinds of feed (commercial concentrate vs whole supplemented barley) were compared in unweaned lambs and lambs weaned at 40 days of age, fattened at pasture and slaughtered at 28 kg live weight, in order to observe their effects on meat quality and fatty acid composition. The weaning status influenced fatness; unweaned lambs displayed a greater carcass fatness score and more kidney knob and channel fat than weaned lambs. Compared with the unweaned animals, weaned lambs exhibited higher pH values at 0 h and 45 min in the m. longissimus thoracis (LT) and at 45 min and 24 h in the m. semitendinosus. The redness index (a*) of the m. LT of weaned lambs was higher than that of unweaned lambs, and lambs fed concentrate displayed a higher yellowness index (b*) and a higher Hue value than those given whole barley. Water-holding capacity did not vary with the treatments studied. The proportion of saturated fatty acids (SFA) in intramuscular fat was higher (P⩾0.001) in unweaned lambs than in weaned ones while, on the other hand, the latter displayed a higher proportion of monounsaturated fatty acids (MUFA) and a higher n-6/n-3 ratio in the same tissue. As was the case with intramuscular fat, the subcutaneous fat of unweaned lambs exhibited higher proportions of medium-chain fatty acids (C12:0, C14:0 y C16:0) and lower ones of stearic (C18:0) and oleic (C18:1) fatty acids than that of weaned lambs. Higher levels of heptadecenoic acid (C17:1) were found in the subcutaneous fat of lambs fed whole barley than in that of lambs given concentrate. PUFA/SFA and n-6/n-3 ratios were lower in the m. LT than in the m. quadriceps femoris.

  16. Muscular contraction mode differently affects autonomic control during heart rate matched exercise.

    PubMed

    Weippert, Matthias; Behrens, Martin; Gonschorek, Ray; Bruhn, Sven; Behrens, Kristin

    2015-01-01

    The precise contributions of afferent feedback to cardiovascular and respiratory responses to exercise are still unclear. The aim of this crossover study was to assess whether and how autonomic cardiovascular and respiratory control differed in response to dynamic (DYN) and isometric contractions (ISO) at a similar, low heart rate (HR) level. Therefore, 22 healthy males (26.7 ± 3.6 yrs) performed two kinds of voluntary exercises at similar HR: ISO and DYN of the right quadriceps femoris muscle. Although HR was eqivalent (82 ± 8 bpm for DYN and ISO, respectively), rating of exertion, blood pressures, and rate pressure product were higher, whereas breathing frequency, minute ventilation, oxygen uptake and carbon dioxide output were significantly lower during ISO. Tidal volume, end-tidal partial pressures of O2 and CO2, respiratory exchange ratio and capillary blood lactate concentration were comparable between both contraction modes. Heart rate variability (HRV) indicators, SDNN, HF-Power and LF-Power, representing both vagal and sympathetic influences, were significantly higher during ISO. Sample entropy, a non-linear measure of HRV was also significantly affected by contraction mode. It can be concluded that, despite the same net effect on HR, the quality of cardiovascular control during low intensity exercise is significantly different between DYN and ISO. HRV analysis indicated a sympatho-vagal coactivation during ISO. Whether mechanoreceptor feedback alone, a change in central command, or the interaction of both mechanisms is the main contributor of the distinct autonomic responses to the different exercise modes remains to be elucidated.

  17. Quantitative MRI and strength measurements in the assessment of muscle quality in Duchenne muscular dystrophy.

    PubMed

    Wokke, B H; van den Bergen, J C; Versluis, M J; Niks, E H; Milles, J; Webb, A G; van Zwet, E W; Aartsma-Rus, A; Verschuuren, J J; Kan, H E

    2014-05-01

    The purpose of this study was to assess leg muscle quality and give a detailed description of leg muscle involvement in a series of Duchenne muscular dystrophy patients using quantitative MRI and strength measurements. Fatty infiltration, as well as total and contractile (not fatty infiltrated) cross sectional areas of various leg muscles were determined in 16 Duchenne patients and 11 controls (aged 8-15). To determine specific muscle strength, four leg muscle groups (quadriceps femoris, hamstrings, anterior tibialis and triceps surae) were measured and related to the amount of contractile tissue. In patients, the quadriceps femoris showed decreased total and contractile cross sectional area, attributable to muscle atrophy. The total, but not the contractile, cross sectional area of the triceps surae was increased in patients, corresponding to hypertrophy. Specific strength decreased in all four muscle groups of Duchenne patients, indicating reduced muscle quality. This suggests that muscle hypertrophy and fatty infiltration are two distinct pathological processes, differing between muscle groups. Additionally, the quality of remaining muscle fibers is severely reduced in the legs of Duchenne patients. The combination of quantitative MRI and quantitative muscle testing could be a valuable outcome parameter in longitudinal studies and in the follow-up of therapeutic effects.

  18. Effects of ACL reconstruction surgery on muscle activity of the lower limb during a jump-cut maneuver in males and females

    PubMed Central

    Coats-Thomas, Margaret S.; Miranda, Daniel L.; Badger, Gary J.; Fleming, Braden C.

    2013-01-01

    We compared muscle activity of the quadriceps, hamstring, and gastrocnemius muscles when ACL-intact (ACLINT) and ACL-reconstructed (ACLREC) male and female subjects performed a jump-cut task. Surface electromyography sensors were used to evaluate time to peak muscle activity and muscle activity ratios. Rectus femoris (RF) and vastus medialis (VM) peak timing was 71 ms and 78 ms earlier in ACLINT than in ACLREC subjects, respectively. Biceps femoris (BF) peak timing was 90 ms earlier in ACLINT than in ACLREC subjects and 75 ms earlier in females than in males. Medial gastrocnemius (MG) muscle peak timing was 77 ms earlier in ACLINT than in ACLREC subjects. Lateral gastrocnemius (LG) and MG muscle peak times were 106 ms and 87 ms earlier in females than in males, respectively. The RF, VM, BF and MG peaked later in ACLREC than in ACLINT subjects. There was evidence suggesting that the loading phase quadriceps:hamstring (quad:ham) muscle activity ratio was greater in ACLREC than in ACLINT subjects. Finally, the injury risk phase quad:ham muscle activity ratio was found to be 4.8 times greater in females than in males. In conclusion, there are differences in muscle activity related to ACL status and sex that could potentially help explain graft failure risk and the sex bias. PMID:23966333

  19. Acute Low-Dose Caffeine Supplementation Increases Electromyographic Fatigue Threshold in Healthy Men.

    PubMed

    Morse, Jacob J; Pallaska, Gramos; Pierce, Patrick R; Fields, Travis M; Galen, Sujay S; Malek, Moh H

    2016-11-01

    Morse, JJ, Pallaska, G, Pierce, PR, Fields, TM, Galen, SS, and Malek, MH. Acute low-dose caffeine supplementation increases electromyographic fatigue threshold in healthy men. J Strength Cond Res 30(11): 3236-3241, 2016-The purpose of this study is to determine whether consumption of a single low-dose caffeine drink will delay the onset of the electromyographic fatigue threshold (EMGFT) in the superficial quadriceps femoris muscles. We hypothesize that the EMGFT values for the caffeine condition will be significantly higher than the EMGFT values for the placebo condition. On separate occasions, 10 physically active men performed incremental single-leg knee-extensor ergometry 1 hour after caffeine (200 mg) or placebo consumption. The EMGFT was determined for each participant for both conditions. The results indicated a significant increase for maximal power output (16%; p = 0.004) and EMGFT (45%; p = 0.004) in the caffeine condition compared with placebo. These findings suggest that acute low-dose caffeine supplementation delays neuromuscular fatigue in the quadriceps femoris muscles.

  20. Muscle Activation Differs between Three Different Knee Joint-Angle Positions during a Maximal Isometric Back Squat Exercise

    PubMed Central

    Jarbas da Silva, Josinaldo; Jon Schoenfeld, Brad; Nardi, Priscyla Silva Monteiro; Pecoraro, Silvio Luis; D'Andréa Greve, Julia Maria; Hartigan, Erin

    2016-01-01

    The purpose of this study was to compare muscle activation of the lower limb muscles when performing a maximal isometric back squat exercise over three different positions. Fifteen young, healthy, resistance-trained men performed an isometric back squat at three knee joint angles (20°, 90°, and 140°) in a randomized, counterbalanced fashion. Surface electromyography was used to measure muscle activation of the vastus lateralis (VL), vastus medialis (VM), rectus femoris (RF), biceps femoris (BF), semitendinosus (ST), and gluteus maximus (GM). In general, muscle activity was the highest at 90° for the three quadriceps muscles, yet differences in muscle activation between knee angles were muscle specific. Activity of the GM was significantly greater at 20° and 90° compared to 140°. The BF and ST displayed similar activation at all joint angles. In conclusion, knee position alters muscles activation of the quadriceps and gluteus maximus muscles. An isometric back squat at 90° generates the highest overall muscle activation, yet an isometric back squat at 140° generates the lowest overall muscle activation of the VL and GM only. PMID:27504484

  1. Postural stability and responses to vibrations in patients after anterior cruciate ligament surgical reconstruction.

    PubMed

    Hirjaková, Z; Šingliarová, H; Bzdúšková, D; Kimijanová, J; Bučková, K; Valkovič, P; Hlavačka, F

    2016-10-24

    The aim of the study was to evaluate the effect of surgical reconstruction of anterior cruciate ligament (ACL) on postural stability and responses to lower limb (LL) muscles vibrations. Centre of pressure (CoP) was measured in 17 subjects during stance on firm/foam surface with eyes open/closed and during unilateral vibrations of LL muscles (m. triceps surae - TS, m. quadriceps femoris - Q, m. quadriceps femoris and hamstrings simultaneously - QH). The measurements were performed: 1) preoperatively, 2) six weeks and 3) three months after the reconstruction. Decreased postural stability was documented six weeks after the reconstruction compared to preoperative measurement. Three months after the reconstruction significant improvement was observed during stance on foam surface with eyes closed. Preoperatively, altered reactions of LL with ACL lesion compared to intact LL were manifested by slower response in first 3 s of TS vibration and by increased CoP shift in last 5 s of QH vibration. After the reconstruction, we observed slower CoP reaction and decreased CoP shift during TS vibration of LL with ACL lesion compared to preoperative level. Posturography during quiet stance and during TS vibration reliably detect postural changes due to ACL reconstruction and can be potentially useful in clinical practice.

  2. Social influence: compliance and conformity.

    PubMed

    Cialdini, Robert B; Goldstein, Noah J

    2004-01-01

    This review covers recent developments in the social influence literature, focusing primarily on compliance and conformity research published between 1997 and 2002. The principles and processes underlying a target's susceptibility to outside influences are considered in light of three goals fundamental to rewarding human functioning. Specifically, targets are motivated to form accurate perceptions of reality and react accordingly, to develop and preserve meaningful social relationships, and to maintain a favorable self-concept. Consistent with the current movement in compliance and conformity research, this review emphasizes the ways in which these goals interact with external forces to engender social influence processes that are subtle, indirect, and outside of awareness.

  3. Influence Analysis of Ranking Data.

    ERIC Educational Resources Information Center

    Poon, Wai-Yin; Chan, Wai

    2002-01-01

    Developed diagnostic measures to identify observations in Thurstonian models for ranking data that unduly influence parameter estimates obtained by the partition maximum likelihood approach of W. Chan and P. Bender (1998). (SLD)

  4. Language may indeed influence thought.

    PubMed

    Zlatev, Jordan; Blomberg, Johan

    2015-01-01

    We discuss four interconnected issues that we believe have hindered investigations into how language may affect thinking. These have had a tendency to reappear in the debate concerning linguistic relativity over the past decades, despite numerous empirical findings. The first is the claim that it is impossible to disentangle language from thought, making the question concerning "influence" pointless. The second is the argument that it is impossible to disentangle language from culture in general, and from social interaction in particular, so it is impossible to attribute any differences in the thought patterns of the members of different cultures to language per se. The third issue is the objection that methodological and empirical problems defeat all but the most trivial version of the thesis of linguistic influence: that language gives new factual information. The fourth is the assumption that since language can potentially influence thought from "not at all" to "completely," the possible forms of linguistic influence can be placed on a cline, and competing theories can be seen as debating the actual position on this cline. We analyze these claims and show that the first three do not constitute in-principle objections against the validity of the project of investigating linguistic influence on thought, and that the last one is not the best way to frame the empirical challenges at hand. While we do not argue for any specific theory or mechanism for linguistic influence on thought, our discussion and the reviewed literature show that such influence is clearly possible, and hence in need of further investigations.

  5. Musculotopic organization of the motor neurons supplying the mouse hindlimb muscles: a quantitative study using Fluoro-Gold retrograde tracing.

    PubMed

    Bácskai, Tímea; Rusznák, Zoltán; Paxinos, George; Watson, Charles

    2014-01-01

    We have mapped the motor neurons (MNs) supplying the major hindlimb muscles of transgenic (C57/BL6J-ChAT-EGFP) and wild-type (C57/BL6J) mice. The fluorescent retrograde tracer Fluoro-Gold was injected into 19 hindlimb muscles. Consecutive transverse spinal cord sections were harvested, the MNs counted, and the MN columns reconstructed in 3D. Three longitudinal MN columns were identified. The dorsolateral column extends from L4 to L6 and consists of MNs innervating the crural muscles and the foot. The ventrolateral column extends from L1 to L6 and accommodates MNs supplying the iliopsoas, gluteal, and quadriceps femoris muscles. The middle part of the ventral horn hosts the central MN column, which extends between L2 and L6 and consists of MNs for the thigh adductor, hamstring, and quadratus femoris muscles. Within these longitudinal columns, the arrangement of the different MN groups reflects their somatotopic organization. MNs innervating muscles developing from the dorsal (e.g., quadriceps) and ventral muscle mass (e.g., hamstring) are situated in the lateral and medial part of the ventral gray, respectively. MN pools belonging to proximal muscles (e.g., quadratus femoris and iliopsoas) are situated ventral to those supplying more distal ones (e.g., plantar muscles). Finally, MNs innervating flexors (e.g., posterior crural muscles) are more medial than those belonging to extensors of the same joint (e.g., anterior crural muscles). These data extend and modify the MN maps in the recently published atlas of the mouse spinal cord and may help when assessing neuronal loss associated with MN diseases.

  6. Genetic influences on adolescent behavior.

    PubMed

    Dick, Danielle M; Adkins, Amy E; Kuo, Sally I-Chun

    2016-11-01

    Adolescence is a transitional, developmental phase with marked shifts in behavior, particularly as related to risk-taking and experimentation. Genetic influences on adolescent behavior also show marked changes across this developmental period; in fact, adolescence showcases the dynamic nature of genetic influences on human behavior. Using the twin studies literature on alcohol use and misuse, we highlight several principles of genetic influence on adolescent behavior. We illustrate how genetic influences change (increase) across adolescence, as individuals have more freedom to express their predispositions and to shape their social worlds. We show how there are multiple genetic pathways to risk, and how the environment can moderate the importance of genetic predispositions. Finally, we review the literature aimed at identifying specific genes involved in adolescent behavior and understanding how identified genes impact adolescent outcomes. Ultimately, understanding how genetic predispositions combine with environmental influences to impact pathways of risk and resilience should be translated into improved prevention and intervention efforts; this remains a rich area for future research.

  7. Individual influence on model selection.

    PubMed

    Sterba, Sonya K; Pek, Jolynn

    2012-12-01

    Researchers in psychology are increasingly using model selection strategies to decide among competing models, rather than evaluating the fit of a given model in isolation. However, such interest in model selection outpaces an awareness that one or a few cases can have disproportionate impact on the model ranking. Though case influence on the fit of a single model in isolation has been often studied, case influence on model selection results is greatly underappreciated in psychology. This article introduces the issue of case influence on model selection and proposes 3 influence diagnostics for commonly used selection indices: the chi-square difference test, Bayesian information criterion, and Akaike's information criterion. These 3 diagnostics can be obtained simply from the byproducts of full information maximum likelihood estimation without heavy computational burden. We provide practical information on the interpretation and behavior of these diagnostics for applied researchers and provide software code to facilitate their use. Simulated and empirical examples involving different kinds of model comparison scenarios encountered in cross-sectional, longitudinal, and multilevel research as well as involving different kinds of outcome distributions illustrate the generality of the proposed diagnostics. An awareness of how cases influence model selection results is shown to aid researchers in understanding how representative their sample level results are at the case level.

  8. Influence of Regional Difference in Bone Mineral Density on Hip Fracture Site in Elderly Females by Finite Element Analysis.

    PubMed

    Lin, Z L; Li, P F; Pang, Z H; Zheng, X H; Huang, F; Xu, H H; Li, Q L

    2015-11-01

    Hip fracture is a kind of osteoporotic fractures in elderly patients. Its important monitoring indicator is to measure bone mineral density (BMD) using DXA. The stress characteristics and material distribution in different parts of the bones can be well simulated by three-dimensional finite element analysis. Our previous studies have demonstrated a linear positive correlation between clinical BMD and the density of three-dimensional finite element model of the femur. However, the correlation between the density variation between intertrochanteric region and collum femoris region of the model and the fracture site has not been studied yet. The present study intends to investigate whether the regional difference in the density of three-dimensional finite element model of the femur can be used to predict hip fracture site in elderly females. The CT data of both hip joints were collected from 16 cases of elderly female patients with hip fractures. Mimics 15.01 software was used to reconstruct the model of proximal femur on the healthy side. Ten kinds of material properties were assigned. In Abaqus 6.12 software, the collum femoris region and intertrochanteric region were, respectively, drawn for calculating the corresponding regional density of the model, followed by prediction of hip fracture site and final comparison with factual fracture site. The intertrochanteric region/collum femoris region density was [(1.20 ± 0.02) × 10(6)] on the fracture site and [(1.22 ± 0.03) × 10(6)] on the non-fracture site, and the difference was statistically significant (P = 0.03). Among 16 established models of proximal femur on the healthy side, 14 models were consistent with the actual fracture sites, one model was inconsistent, and one model was unpredictable, with the coincidence rate of 87.5 %. The intertrochanteric region or collum femoris region with lower BMD is more prone to hip fracture of the type on the corresponding site.

  9. Vestibular influences on human postural control in combinations of pitch and roll planes reveal differences in spatiotemporal processing.

    PubMed

    Carpenter, M G; Allum, J H; Honegger, F

    2001-09-01

    The present study examined the influence of bilateral peripheral vestibular loss (BVL) in humans on postural responses to multidirectional surface rotations in the pitch and roll planes. Specifically, we examined the effects of vestibular loss on the directional sensitivity, timing, and amplitude of early stretch, balance correcting, and stabilizing reactions in postural leg and trunk muscles as well as changes in ankle torque and trunk angular velocity following multidirectional rotational perturbations of the support surface. Fourteen normal healthy adults and five BVL patients stood on a dual axis rotating platform which rotated 7.5 degrees at 50 degrees/s through eight different directions of pitch and roll combinations separated by 45 degrees. Directions were randomized within a series of 44 perturbation trials which were presented first with eyes open, followed by a second series of trials with eyes closed. Vestibular loss did not influence the range of activation or direction of maximum sensitivity for balance correcting responses (120-220 ms). Response onsets at approximately 120 ms were normal in tibialis anterior (TA), soleus (SOL), paraspinals (PARAS), or quadriceps muscles. Only SOL muscle activity demonstrated a 38- to 45-ms delay for combinations of forward (toe-down) and roll perturbations in BVL patients. The amplitude of balance correcting responses in leg muscles between 120 and 220 ms was, with one exception, severely reduced in BVL patients for eyes open and eyes closed conditions. SOL responses were decreased bilaterally for toe-up and toe-down perturbations, but more significantly reduced in the downhill (load-bearing) leg for combined roll and pitch perturbations. TA was significantly reduced bilaterally for toe-up perturbations, and in the downhill leg for backward roll perturbations. Forward perturbations, however, elicited significantly larger TA activity in BVL between 120 and 220 ms compared to normals, which would act to further

  10. Antecedent influences on behavior disorders.

    PubMed Central

    Smith, R G; Iwata, B A

    1997-01-01

    The influence of antecedent events on behavior disorders has been relatively understudied by applied behavior analysts. This lack of research may be due to a focus on consequences as determinants of behavior and a historical disagreement on a conceptual framework for describing and interpreting antecedent variables. We suggest that antecedent influences can be described using terms derived from basic behavioral principles and that their functional properties can be adequately interpreted as discriminative and establishing operations. A set of studies on assessment and treatment of behavior disorders was selected for review based on their relevance to the topic of antecedent events. These studies were categorized as focusing on assessment of antecedent events, antecedent treatments for behavior disorders maintained by either positive or negative reinforcement, and special cases of antecedent events in behavior disorders. Some directions for future research on antecedent influences in the analysis and treatment of behavior disorders are discussed. PMID:9210312

  11. Influence analysis of Github repositories.

    PubMed

    Hu, Yan; Zhang, Jun; Bai, Xiaomei; Yu, Shuo; Yang, Zhuo

    2016-01-01

    With the support of cloud computing techniques, social coding platforms have changed the style of software development. Github is now the most popular social coding platform and project hosting service. Software developers of various levels keep entering Github, and use Github to save their public and private software projects. The large amounts of software developers and software repositories on Github are posing new challenges to the world of software engineering. This paper tries to tackle one of the important problems: analyzing the importance and influence of Github repositories. We proposed a HITS based influence analysis on graphs that represent the star relationship between Github users and repositories. A weighted version of HITS is applied to the overall star graph, and generates a different set of top influential repositories other than the results from standard version of HITS algorithm. We also conduct the influential analysis on per-month star graph, and study the monthly influence ranking of top repositories.

  12. Greek influence on Babylonian astronomy?

    NASA Astrophysics Data System (ADS)

    Steele, J. M.

    Astronomy in Babylonia during the first millennium BC developed out of a long tradition of observing and interpreting the sky into a science that was both observational and theoretical. It is well established that these developments influenced the practice of astronomy in neighbouring cultures in the Indus valley, Egypt and the Greco-Roman world. However, it is less clear whether there was any significant input from foreign cultures into the development of Babylonian astronomy. In this paper I examine the evidence for possible traces of Greek influence on Babylonian astronomy during the late first millennium BC. In particular, I discuss two possible cases of Greek influence that have been proposed in recent years: the naming of certain zodiacal signs and a value for the length of the year found on a Babylonian text that may be based upon Greek observations of summer solstices.

  13. Strong relationships exist between muscle volume, joint power and whole-body external mechanical power in adults and children.

    PubMed

    O'Brien, Thomas D; Reeves, Neil D; Baltzopoulos, Vasilios; Jones, David A; Maganaris, Constantinos N

    2009-06-01

    The present study investigated whether differences between adults and children in mechanical power during single-joint knee extension tasks and the complex multijoint task of jumping could be explained by differences in the quadriceps femoris muscle volume. Peak power was calculated during squat jumps, from the integral of the vertical force measured by a force plate, and during concentric knee extensions at 30, 90, 120, 180 and 240 deg s(-1), and muscle volume was measured from magnetic resonance images for 10 men, 10 women, 10 prepubertal boys and 10 prepubertal girls. Peak power during jumping and isokinetic knee extension was significantly higher in men than in women, and in both adult groups compared with children (P < 0.01), although there were no differences between boys and girls. When power was normalized to muscle volume, the intergroup differences ceased to exist for both tasks. Peak power correlated significantly with quadriceps volume (P < 0.01), with r(2) values of 0.8, 0.86, 0.81, 0.78 and 0.81 from isokinetic knee extension at angular velocities of 30, 90, 120, 180 and 240 deg s(-1), respectively, and with an r(2) value of 0.9 from squat jumps. These results indicate that the quadriceps femoris muscle volume accounts largely for the increase in power that occurs with maturation in the two genders not only in kinematically constrained knee extensions but also in multijoint tasks. Future studies should examine the role of other factors relating to the generation and transmission of contractile power, such as muscle architecture, tendon stiffness and external mechanical leverage.

  14. Predicting muscle forces of individuals with hemiparesis following stroke

    PubMed Central

    Kesar, Trisha M; Ding, Jun; Wexler, Anthony S; Perumal, Ramu; Maladen, Ryan; Binder-Macleod, Stuart A

    2008-01-01

    Background Functional electrical stimulation (FES) has been used to improve function in individuals with hemiparesis following stroke. An ideal functional electrical stimulation (FES) system needs an accurate mathematical model capable of designing subject and task-specific stimulation patterns. Such a model was previously developed in our laboratory and shown to predict the isometric forces produced by the quadriceps femoris muscles of able-bodied individuals and individuals with spinal cord injury in response to a wide range of clinically relevant stimulation frequencies and patterns. The aim of this study was to test our isometric muscle force model on the quadriceps femoris, ankle dorsiflexor, and ankle plantar-flexor muscles of individuals with post-stroke hemiparesis. Methods Subjects were seated on a force dynamometer and isometric forces were measured in response to a range of stimulation frequencies (10 to 80-Hz) and 3 different patterns. Subject-specific model parameter values were obtained by fitting the measured force responses from 2 stimulation trains. The model parameters thus obtained were then used to obtain predicted forces for a range of frequencies and patterns. Predicted and measured forces were compared using intra-class correlation coefficients, r2 values, and model error relative to the physiological error (variability of measured forces). Results Results showed excellent agreement between measured and predicted force-time responses (r2 >0.80), peak forces (ICCs>0.84), and force-time integrals (ICCs>0.82) for the quadriceps, dorsiflexor, and plantar-fexor muscles. The model error was within or below the +95% confidence interval of the physiological error for >88% comparisons between measured and predicted forces. Conclusion Our results show that the model has potential to be incorporated as a feed-forward controller for predicting subject-specific stimulation patterns during FES. PMID:18304360

  15. Language may indeed influence thought

    PubMed Central

    Zlatev, Jordan; Blomberg, Johan

    2015-01-01

    We discuss four interconnected issues that we believe have hindered investigations into how language may affect thinking. These have had a tendency to reappear in the debate concerning linguistic relativity over the past decades, despite numerous empirical findings. The first is the claim that it is impossible to disentangle language from thought, making the question concerning “influence” pointless. The second is the argument that it is impossible to disentangle language from culture in general, and from social interaction in particular, so it is impossible to attribute any differences in the thought patterns of the members of different cultures to language per se. The third issue is the objection that methodological and empirical problems defeat all but the most trivial version of the thesis of linguistic influence: that language gives new factual information. The fourth is the assumption that since language can potentially influence thought from “not at all” to “completely,” the possible forms of linguistic influence can be placed on a cline, and competing theories can be seen as debating the actual position on this cline. We analyze these claims and show that the first three do not constitute in-principle objections against the validity of the project of investigating linguistic influence on thought, and that the last one is not the best way to frame the empirical challenges at hand. While we do not argue for any specific theory or mechanism for linguistic influence on thought, our discussion and the reviewed literature show that such influence is clearly possible, and hence in need of further investigations. PMID:26582997

  16. The Anxiety of Influence and the Influence of Anxiety.

    ERIC Educational Resources Information Center

    Kountz, Carol

    A composition researcher collected stories from students with writing anxiety, using qualitative research tools of interview and interpretation. In literary theory it is not unusual to speak of anxiety of influence when referring to the torment of proving one is equal to a revered author. The critic Harold Bloom presented it as his theory of the…

  17. Influencing the future of AGU

    NASA Astrophysics Data System (ADS)

    McPhaden, Michael; Finn, Carol; McEntee, Chris

    2012-01-01

    Steve Jobs, visionary cofounder of Apple, Inc., once said, “Everyone here has the sense that right now is one of those moments when we are influencing the future.” This statement aptly describes AGU at this time as the Board of Directors and the Council continue to influence the future in exciting ways by advancing our strategic plan (http://www.agu.org/about/mission.shtml). Both governing bodies held meetings in San Francisco immediately preceding the 2011 AGU Fall Meeting. The agendas for both meetings, along with the key outcomes, are posted on AGU's Web site (http://www.agu.org/about/governance/).

  18. Surface Organization Influences Bistable Vision

    ERIC Educational Resources Information Center

    Graf, Erich W.; Adams, Wendy J.

    2008-01-01

    A priority for the visual system is to construct 3-dimensional surfaces from visual primitives. Information is combined across individual cues to form a robust representation of the external world. Here, it is shown that surface completion relying on multiple visual cues influences relative dominance during binocular rivalry. The shape of a…

  19. Factors That Influence Teacher Attrition.

    ERIC Educational Resources Information Center

    Gonzalez, Patricia

    1995-01-01

    External, employment, and personal factors which influence teacher decisions to stay, leave, or transfer from teaching assignments are discussed, with emphasis on special education teachers. Factors attributed to teacher attrition in urban and rural environments also are briefly reviewed, along with attrition of related services professionals.…

  20. Machiavellian Beliefs and Social Influence.

    ERIC Educational Resources Information Center

    O'Hair, Dan; Cody, Michael J.

    1987-01-01

    Replicates previous findings of separate Machiavellian belief constructs (Deceit, Flatter, Immorality, and Cynicism). Indicates that different constructs predict selection of compliance-gaining strategies; for example, actors who scored high on Immorality used more referent influence on superiors. Discusses implications of this study concerning a…

  1. Family Influences on Early Development.

    ERIC Educational Resources Information Center

    Silber, Sharon

    1989-01-01

    The article reviews the literature concerning family influences on early childhood development. Implications of this literature for intervention planning with high risk children and families are suggested. Topics covered include the early parent-child relationship, disciplinary strategies, stimulation, parental instruction and expectations, the…

  2. Young Children's Influence in Preschool

    ERIC Educational Resources Information Center

    Emilson, Anette

    2007-01-01

    The purpose of this study was to investigate how very young children can influence their daily life in preschool, in relation to teacher control. The specific questions studied were: What opportunities do the children have to make their own choices and take the initiative? How does teacher control manifest itself? What form do permanent…

  3. Factors Influencing College Science Success

    ERIC Educational Resources Information Center

    Tai, Robert H.; Sadler, Philip M.; Mintzes, Joel J.

    2006-01-01

    In this paper, the authors report some of the salient findings of a large-scale, four-year national study, conducted at the Harvard-Smithsonian Center for Astrophysics, entitled "Factors Influencing College Science Success" (FICSS), which surveyed college students who enrolled in first-year biology, chemistry, and physics courses…

  4. The Influence of Marketing Education.

    ERIC Educational Resources Information Center

    Leventhal, Jerome I.

    2002-01-01

    A look at the history of marketing education shows how it has influenced the education of students and how its concepts are still being used in education today. Marketing educators were pioneers in educational opportunities for women, performance-based education, cooperative education, and leadership development. (JOW)

  5. Influence of convection on microstructure

    NASA Technical Reports Server (NTRS)

    Wilcox, William R.; Caram, Rubens; Mohanty, A. P.; Seth, Jayshree

    1990-01-01

    The mechanism responsible for the difference in microstructure caused by solidifying the MnBi-Bi eutectic in space is sought. The objectives for the three year period are as follows: (1) completion of the following theoretical analyses - determination of the influence of the Soret effect on the average solid composition versus distance of off-eutectic mixtures directionally solidified in the absence of convection, determination of the influence of convection on the microstructure of off-eutectic mixtures using a linear velocity profile in the adjacent melt, determination of the influence of volumetric changes during solidification on microconvection near the freezing interface and on microstructure, and determination of the influence of convection on microstructure when the MnBi fibers project out in front of the bismuth matrix; (2) search for patterns in the effect of microgravity on different eutectics (for example, eutectic composition, eutectic temperature, usual microstructure, densities of pure constituents, and density changes upon solidification); and (3) determination of the Soret coefficient and the diffusion coefficient for Mn-Bi melts near the eutectic composition, both through laboratory experiements to be performed here and from data from Shuttle experiments.

  6. Soft Factors Influence College Enrollment

    ERIC Educational Resources Information Center

    Fogg, Neeta P.; Harrington, Paul E.

    2010-01-01

    Evidence about the role that "soft factors" like student engagement and school environment play in influencing whether high school students go on to enroll in college is hard to come by. Over the past two years, the Center for Labor Market Studies (CLMS) of Northeastern University, with support from the Nellie Mae Education Foundation…

  7. Phonological Awareness: Factors of Influence

    ERIC Educational Resources Information Center

    Frohlich, Linda Paulina; Petermann, Franz; Metz, Dorothee

    2013-01-01

    Early child development is influenced by various genetic and environmental factors. This study aims to identify factors that affect the phonological awareness of preschool and first grade children. Based on a sample of 330 German-speaking children (mean age = 6.2 years) the following domains were evaluated: Parent factors, birth and pregnancy,…

  8. Individual Influence on Model Selection

    ERIC Educational Resources Information Center

    Sterba, Sonya K.; Pek, Jolynn

    2012-01-01

    Researchers in psychology are increasingly using model selection strategies to decide among competing models, rather than evaluating the fit of a given model in isolation. However, such interest in model selection outpaces an awareness that one or a few cases can have disproportionate impact on the model ranking. Though case influence on the fit…

  9. Influences on Garifuna Youth's Education.

    ERIC Educational Resources Information Center

    Lewis, Karla

    This paper examines the influences on Garifuna (also known as Caribs) youth education through the voices of Garifuna educators and youths. The paper emphasizes, in both its content and methodology, that discussion of education in the Caribbean and specifically Belize cannot be separated from the educators' experiences and the adolescents'…

  10. Microbial Influenced Corrosion (MIC) Study

    DTIC Science & Technology

    2012-05-23

    fumigatus Fusarium oxysporum Fungal Consortium Penicillium oxalicum Rhodoturula sp. Trichoderma sp. Dosed with microbes known to influence Control...Hypocrea jecorina (FI-1) Penicillium oxalicum (FI-12) – Pleosporacea sp. (FI-17) Rhodoturala mucilaginosa (FI-7) – Ustilago maydis (FI-13) T t S t• es

  11. Influences on Adolescents' Vocational Development.

    ERIC Educational Resources Information Center

    Mortimer, Jeylan T.; And Others

    A study charted family, school, workplace, and community experiences that are relevant to the vocational development of high school students, focusing on five areas of influence: allowance practices within the family, economic status, paid work experience, volunteerism, and gender differences. The data were from the "Youth Development…

  12. Intelligence: Genetic and Environmental Influences.

    ERIC Educational Resources Information Center

    Cancro, Robert, Ed.

    This book on the genetic and environmental influences on intelligence is comprised of the following papers: "The Structure of Intelligence in Relation to the Nature-Nurture Controversy," R. B. Cattell; "Theory of Intelligence," L. G. Humphreys; "Using Measured Intelligence Intelligently," P. R. Merrifield; "Intelligence: Definition, Theory, and…

  13. Influence

    NASA Astrophysics Data System (ADS)

    Jassim, Salah Abdul-Jabbar; Zumaila, Abubaker A. Rashid Ali; Al Waly, Gassan Abdella Ali

    CdS thin films were deposited onto glass substrates at three different temperatures (20, 100 and 200 °C) by vacuum thermal evaporation at 10-5 Torr using pure crystal as evaporated targets. The effects of substrate temperature on structural, electrical and optical properties were studied. Structural analysis using X-ray diffraction (XRD) and scanning electronic microscope (SEM) revealed that the films are polycrystalline in nature with a hexagonal wurtzite structure having (0 0 2) plane as the preferred orientation. The crystalline size (D), dislocation density (δ), strain (ε) and texture coefficient TC(hkl) were calculated. All the films have high optical transmittance (>80%) in the visible range. The optical band gap values are found to be in the range of (2.3-2.43 eV) and found to decrease with increase in substrate temperature. DC electrical conductivity was carried out at room temperature indicating a very low electrical conductivity.

  14. Bacterial Influences on Animal Origins

    PubMed Central

    Alegado, Rosanna A.; King, Nicole

    2014-01-01

    Animals evolved in seas teeming with bacteria, yet the influences of bacteria on animal origins are poorly understood. Comparisons among modern animals and their closest living relatives, the choanoflagellates, suggest that the first animals used flagellated collar cells to capture bacterial prey. The cell biology of prey capture, such as cell adhesion between predator and prey, involves mechanisms that may have been co-opted to mediate intercellular interactions during the evolution of animal multicellularity. Moreover, a history of bacterivory may have influenced the evolution of animal genomes by driving the evolution of genetic pathways for immunity and facilitating lateral gene transfer. Understanding the interactions between bacteria and the progenitors of animals may help to explain the myriad ways in which bacteria shape the biology of modern animals, including ourselves. PMID:25280764

  15. Factors influencing susceptibility to metals.

    PubMed Central

    Gochfeld, M

    1997-01-01

    Although the long-neglected field of human susceptibility to environmental toxicants is currently receiving renewed attention, there is only scant literature on factors influencing susceptibility to heavy metals. Genetic factors may influence the availability of sulfhydryl-containing compounds such as glutathione and metallothionein, which modify the distribution and toxicity of certain metals. Age and gender play a role in modifying uptake and distribution, although the mechanisms are often obscure. Concurrent exposure to divalent cations may enhance or reduce the toxicity of certain metals through competition for receptor-mediated transport or targets. Increasing use of biomarkers of exposure should greatly increase our understanding of the underlying distribution of susceptibility to various environmental agents. PMID:9255566

  16. Factors influencing pacing in triathlon.

    PubMed

    Wu, Sam Sx; Peiffer, Jeremiah J; Brisswalter, Jeanick; Nosaka, Kazunori; Abbiss, Chris R

    2014-01-01

    Triathlon is a multisport event consisting of sequential swim, cycle, and run disciplines performed over a variety of distances. This complex and unique sport requires athletes to appropriately distribute their speed or energy expenditure (ie, pacing) within each discipline as well as over the entire event. As with most physical activity, the regulation of pacing in triathlon may be influenced by a multitude of intrinsic and extrinsic factors. The majority of current research focuses mainly on the Olympic distance, whilst much less literature is available on other triathlon distances such as the sprint, half-Ironman, and Ironman distances. Furthermore, little is understood regarding the specific physiological, environmental, and interdisciplinary effects on pacing. Therefore, this article discusses the pacing strategies observed in triathlon across different distances, and elucidates the possible factors influencing pacing within the three specific disciplines of a triathlon.

  17. Factors influencing pacing in triathlon

    PubMed Central

    Wu, Sam SX; Peiffer, Jeremiah J; Brisswalter, Jeanick; Nosaka, Kazunori; Abbiss, Chris R

    2014-01-01

    Triathlon is a multisport event consisting of sequential swim, cycle, and run disciplines performed over a variety of distances. This complex and unique sport requires athletes to appropriately distribute their speed or energy expenditure (ie, pacing) within each discipline as well as over the entire event. As with most physical activity, the regulation of pacing in triathlon may be influenced by a multitude of intrinsic and extrinsic factors. The majority of current research focuses mainly on the Olympic distance, whilst much less literature is available on other triathlon distances such as the sprint, half-Ironman, and Ironman distances. Furthermore, little is understood regarding the specific physiological, environmental, and interdisciplinary effects on pacing. Therefore, this article discusses the pacing strategies observed in triathlon across different distances, and elucidates the possible factors influencing pacing within the three specific disciplines of a triathlon. PMID:25258562

  18. Informational influences on physician referrals.

    PubMed

    Beltramini, R F; Sirsi, A K

    1992-01-01

    Today's health care marketers are devoting significant resources to increase physician referrals, an area vital to their continued survival. The goal of this investigation was to integrate the findings of previous research on physician referrals, and to provide an up-to-date assessment of those influences underlying physician referral behavior. A questionnaire was mailed to 1,800 physicians differing in specialty and years in practice. Three informational influences were found to affect physician referrals: Program Information, Patient Input, and Location. The results suggest a need for specialists and other organizations interested in managing physician referrals to (a) establish and maintain a network of relationships among those physicians referring patients and specialists being referred to through personal communication, (b) maintain a pool of knowledgeable professionals willing to supply relevant and current information to physicians, and (c) provide complete and prompt feedback information to the referring physician. Managerial implications and directions for future research are also discussed.

  19. Reynolds number influences in aeronautics

    NASA Technical Reports Server (NTRS)

    Bushnell, Dennis M.; Yip, Long P.; Yao, Chung-Sheng; Lin, John C.; Lawing, Pierce L.; Batina, John T.; Hardin, Jay C.; Horvath, Thomas J.; Fenbert, James W.; Domack, Christopher S.

    1993-01-01

    Reynolds number, a measure of the ratio of inertia to viscous forces, is a fundamental similarity parameter for fluid flows and therefore, would be expected to have a major influence in aerodynamics and aeronautics. Reynolds number influences are generally large, but monatomic, for attached laminar (continuum) flow; however, laminar flows are easily separated, inducing even stronger, non-monatomic, Reynolds number sensitivities. Probably the strongest Reynolds number influences occur in connection with transitional flow behavior. Transition can take place over a tremendous Reynolds number range, from the order of 20 x 10(exp 3) for 2-D free shear layers up to the order of 100 x 10(exp 6) for hypersonic boundary layers. This variability in transition behavior is especially important for complex configurations where various vehicle and flow field elements can undergo transition at various Reynolds numbers, causing often surprising changes in aerodynamics characteristics over wide ranges in Reynolds number. This is further compounded by the vast parameterization associated with transition, in that any parameter which influences mean viscous flow development (e.g., pressure gradient, flow curvature, wall temperature, Mach number, sweep, roughness, flow chemistry, shock interactions, etc.), and incident disturbance fields (acoustics, vorticity, particulates, temperature spottiness, even electro static discharges) can alter transition locations to first order. The usual method of dealing with the transition problem is to trip the flow in the generally lower Reynolds number wind tunnel to simulate the flight turbulent behavior. However, this is not wholly satisfactory as it results in incorrectly scaled viscous region thicknesses and cannot be utilized at all for applications such as turbine blades and helicopter rotors, nacelles, leading edge and nose regions, and High Altitude Long Endurance and hypersonic airbreathers where the transitional flow is an innately critical

  20. Benchmarking Measures of Network Influence

    NASA Astrophysics Data System (ADS)

    Bramson, Aaron; Vandermarliere, Benjamin

    2016-09-01

    Identifying key agents for the transmission of diseases (ideas, technology, etc.) across social networks has predominantly relied on measures of centrality on a static base network or a temporally flattened graph of agent interactions. Various measures have been proposed as the best trackers of influence, such as degree centrality, betweenness, and k-shell, depending on the structure of the connectivity. We consider SIR and SIS propagation dynamics on a temporally-extruded network of observed interactions and measure the conditional marginal spread as the change in the magnitude of the infection given the removal of each agent at each time: its temporal knockout (TKO) score. We argue that this TKO score is an effective benchmark measure for evaluating the accuracy of other, often more practical, measures of influence. We find that none of the network measures applied to the induced flat graphs are accurate predictors of network propagation influence on the systems studied; however, temporal networks and the TKO measure provide the requisite targets for the search for effective predictive measures.

  1. Government influence on patient organizations.

    PubMed

    Van de Bovenkamp, Hester M; Trappenburg, Margo J

    2011-12-01

    Patient organizations increasingly play an important role in health care decision-making in Western countries. The Netherlands is one of the countries where this trend has gone furthest. In the literature some problems are identified, such as instrumental use of patient organizations by care providers, health insurers and the pharmaceutical industry. To strengthen the position of patient organizations government funding is often recommended as a solution. In this paper we analyze the ties between Dutch government and Dutch patient organizations to learn more about the effects of such a relationship between government and this part of civil society. Our study is based on official government documents and existing empirical research on patient organizations. We found that government influence on patient organizations has become quite substantial with government influencing the organizational structure of patient organizations, the activities these organizations perform and even their ideology. Financing patient organizations offers the government an important means to hold them accountable. Although the ties between patient organizations and the government enable the former to play a role that can be valued as positive by both parties, we argue that they raise problems as well which warrant a discussion on how much government influence on civil society is acceptable.

  2. Benchmarking Measures of Network Influence

    PubMed Central

    Bramson, Aaron; Vandermarliere, Benjamin

    2016-01-01

    Identifying key agents for the transmission of diseases (ideas, technology, etc.) across social networks has predominantly relied on measures of centrality on a static base network or a temporally flattened graph of agent interactions. Various measures have been proposed as the best trackers of influence, such as degree centrality, betweenness, and k-shell, depending on the structure of the connectivity. We consider SIR and SIS propagation dynamics on a temporally-extruded network of observed interactions and measure the conditional marginal spread as the change in the magnitude of the infection given the removal of each agent at each time: its temporal knockout (TKO) score. We argue that this TKO score is an effective benchmark measure for evaluating the accuracy of other, often more practical, measures of influence. We find that none of the network measures applied to the induced flat graphs are accurate predictors of network propagation influence on the systems studied; however, temporal networks and the TKO measure provide the requisite targets for the search for effective predictive measures. PMID:27670635

  3. Genetic influences on social cognition.

    PubMed

    Skuse, David H; Gallagher, Louise

    2011-05-01

    Human social behavior develops under the influence of genetic, environmental, and cultural factors. Social cognition comprises our ability to understand and respond appropriately to other people's social approaches or responses. The concept embraces self-knowledge and theory of mind, or the ability to think about emotions and behavior from the perspective of another person. The neuropeptides oxytocin (OT) and vasopressin (AVP) are now known to play an important role, affecting individual differences in parenting behavior, social recognition, and affiliative behaviors. The processes of social cognition are also supported by reward circuitry, underpinned by the dopaminergic neurotransmitter system. Reward processes build social relationships, in parenting and pair-bonding, and influence social interactions that require trust, or display altruism. The impact of emotional regulation upon social behavior, including mood and anxiety, is also mediated through the serotonergic system. Variation in activity of serotonergic networks in the brain influences emotional responsivity, including subjective feelings, physiological responses, emotional expressions, and the tendency to become engaged in action as a consequence of a feeling state. Genetic variation in the receptors associated with OT, AVP, dopamine, and serotonin has been intensively studied in humans and animal models. Recent findings are building an increasingly coherent picture of regulatory mechanisms.

  4. Visual and graviceptive influences on lower leg EMG activity in humans during brief falls.

    PubMed

    Wicke, R W; Oman, C M

    1982-01-01

    Human subjects were suspended in a safety harness 28 cm above the floor by a steel cable connected to a computer controlled force generator (electromagnetic brake). After the subjects were unexpectedly released, various controlled patterns of downward acceleration (less than 1 g) could be produced. During the falls, EMG activity was recorded simultaneously from the gastrocnemius, soleus, tibialis anterior, rectus femoris, and biceps femoris, along with knee and ankle joint angle in one leg. Subjects were tested eyes closed and also eyes open, both in darkness and in light using a wide field visual display. The display scene could be moved downwards at exactly the same velocity as the moving subject, left fixed with respect to the laboratory ("normal" visual field), or moved upwards at a speed equal to the subject's falling speed (upward moving visual field). Ten vestibularly normal subjects each underwent a total of 45 drops, experiencing three replications of each vision/motion combination used. Under normal visual field conditions, both short and long latency postural responses were seen, which were dependent on the magnitude of the acceleration stimulus. Several of the visual conditions significantly altered both the short and the long latency responses in most of the muscles tested. Effects were particularly prominent in the gastrocnemius and soleus, and were also more pronounced during slow (0.5 g) falls. The upward moving visual field condition increased the short latency EMG reaction in gastrocnemius and soleus for 0.5 g falls. A preliminary scheme for visual-vestibular interaction in short latency EMG responses is presented. Long latency responses are more variable and not conducive to a simple interpretation.

  5. Saltwater upconing zone of influence

    NASA Astrophysics Data System (ADS)

    Jakovovic, Danica; Werner, Adrian D.; de Louw, Perry G. B.; Post, Vincent E. A.; Morgan, Leanne K.

    2016-08-01

    In this study, we define and characterize the saltwater upconing zone of influence (SUZI). The SUZI is the region around a pumping well within which significant rise in the saltwater-freshwater interface occurs. While the zone of influence of a pumping well can be clearly defined in terms of hydraulics (e.g., drawdown), the SUZI has not been recognised and characterised, despite its importance for groundwater decision-making in coastal regions. We explore the SUZI under various conditions and compare common methods of investigation using both axisymmetric (1D and 2D vertical cross-section) and 3D simulations of saltwater upconing at the field scale, based on a combination of numerical and analytical approaches. The SUZI was found to be dependent on the relative magnitudes of pumping, regional flow, distance of the well from the coast, and position of the well above the interface, as expected. The three-dimensional coastal setting simulations revealed an asymmetric shape of the lateral extent of the SUZI, which is largest in the direction parallel to the coast. This occurs because the ocean and the inland extent of the seawater wedge limit the propagation of the SUZI perpendicular to the coast. Predictions of the SUZI using the Ghyben-Herzberg approximation, including cases where sloping interfaces occur (i.e., in contrast to the artificiality of horizontal interfaces used in axisymmetric approaches), provide reasonable first approximations of the SUZI. Numerical modelling of dispersive upconing in the 3D inclined interface case is influenced by practical limits to the model domain size and grid resolution. For example, the no-flow boundary condition at 1500 m from the pumping well elongates the SUZI in the direction parallel to the coast. This study extends previous concepts of well interference, which have previously been based on hydraulics only, by introducing the SUZI and characterising its extent, with consideration given to differences in commonly adopted

  6. Solar influences on global change

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Monitoring of the Sun and the Earth has yielded new knowledge essential to this debate. There is now no doubt that the total radiative energy from the Sun that heats the Earth's surface changes over decadal time scales as a consequence of solar activity. Observations indicate as well that changes in ultraviolet radiation and energetic particles from the Sun, also connected with the solar activity, modulate the layer of ozone that protects the biosphere from the solar ultraviolet radiation. This report reassesses solar influences on global change in the light of this new knowledge of solar and atmospheric variability. Moreover, the report considers climate change to be encompassed within the broader concept of global change; thus the biosphere is recognized to be part of a larger, coupled Earth system. Implementing a program to continuously monitor solar irradiance over the next several decades will provide the opportunity to estimate solar influences on global change, assuming continued maintenance of observations of climate and other potential forcing mechanisms. In the lower atmosphere, an increase in solar radiation is expected to cause global warming. In the stratosphere, however, the two effects produce temperature changes of opposite sign. A monitoring program that would augment long term observations of tropospheric parameters with similar observations of stratospheric parameters could separate these diverse climate perturbations and perhaps isolate a greenhouse footprint of climate change. Monitoring global change in the troposphere is a key element of all facets of the United States Global Change Research Program (USGCRP), not just of the study of solar influences on global change. The need for monitoring the stratosphere is also important for global change research in its own right because of the stratospheric ozone layer.

  7. Visual influences on primate encephalization.

    PubMed

    Kirk, E Christopher

    2006-07-01

    Primates differ from most other mammals in having relatively large brains. As a result, numerous comparative studies have attempted to identify the selective variables influencing primate encephalization. However, none have examined the effect of the total amount of visual input on relative brain size. According to Jerison's principle of proper mass, functional areas of the brain devoted primarily to processing visual information should exhibit increases in size when the amount of visual input to those areas increases. As a result, the total amount of visual input to the brain could exert a large influence on encephalization because visual areas comprise a large proportion of total brain mass in primates. The goal of this analysis is to test the expectation of a direct relationship between visual input and encephalization using optic foramen size and optic nerve size as proxies for total visual input. Data were collected for a large comparative sample of primates and carnivorans, and three primary analyses were undertaken. First, the relationship between relative proxies for visual input and relative endocranial volume were examined using partial correlations and phylogenetic comparative methods. Second, to examine the generality of the results derived for extant primates, a parallel series of partial correlation and comparative analyses were undertaken using data for carnivorans. Third, data for various Eocene and Oligocene primates were compared with those for living primates in order to determine whether the fossil taxa demonstrate a similar relationship between relative brain size and visual input. All three analyses confirm the expectations of proper mass and favor the conclusion that the amount of visual input has been a major influence on the evolution of relative brain size in both primates and carnivorans. Furthermore, this study suggests that differences in visual input may partly explain (1) the high encephalization of primates relative to the primitive

  8. Captain's and first officers' spheres of influence.

    PubMed

    Law, J R; Wilhelm, J A

    1994-01-01

    Although the "crew is increasingly the unit of focus for technical and CRM Training, a recent study documented that individual crew members exert influence over the crew in unique ways. The actions of captains and first officers influenced the overall performance of the "crew" both positively and negatively. Captains most often used briefings and leadership behaviors to influence crews. First Officers, on the other hand, influenced crew performance by their use of Inquiry / Assertion / Advocacy, Preparation / Planning / Vigilance activities, and Technical Proficiency.

  9. Peptides that influence membrane topology

    NASA Astrophysics Data System (ADS)

    Wong, Gerard C. L.

    2014-03-01

    We examine the mechanism of a range of polypeptides that influence membrane topology, including antimicrobial peptides, cell penetrating peptides, viral fusion peptides, and apoptosis proteins, and show how a combination of geometry, coordination chemistry, and soft matter physics can be used to approach a unified understanding. We will also show how such peptides can impact biomedical problems such as auto-immune diseases (psoriasis, lupus), infectious diseases (viral and bacterial infections), and mitochondrial pathologies (under-regulated apoptosis leads to neurodegenerative diseases whereas over-regulated apoptosis leads to cancer.)

  10. Culture and Influence in Multisite Evaluation

    ERIC Educational Resources Information Center

    Kirkhart, Karen E.

    2011-01-01

    Understanding the influence of multisite evaluation requires careful consideration of cultural context. The author illustrates dimensions of influence and culture with excerpts from four National Science Foundation evaluation case studies and summarizes what influence teaches everyone about culture and what culture teaches everyone about…

  11. Corona Discharge Influence on Moulds

    NASA Astrophysics Data System (ADS)

    Scholtz, Vladimir

    2004-09-01

    It is known that the electric discharge has bacteriocid effect. We are interesting on influence of corona discharge on moulds and searching for it's fungicide effect. In this work we study the mould penicillium digitatum by using an easy apparatus, where may be situated two measured samples. One in the burning corona discharge and one in the area with ozone generated by this corona only. We expose the spores of penicillium digitatum on a metal plate and on a cultivating medium on cca 0.01mA, 5kV corona discharge and on generated ozone only for time cca two days. It is the time needed for sprouting of spores and growing of they to a visible size. The pilot results show, that the ozone generated by the corona discharge has none or very low influence on the sprouting and growing of the spores. Direct corona discharge inhibit the sprouting only, but does not kill the spores. In next experiments we will try to find some minimum inhibit and killing concentration of ozone and try to expose the sprout inhibition.

  12. Lexical Influences on Auditory Streaming

    PubMed Central

    Billig, Alexander J.; Davis, Matthew H.; Deeks, John M.; Monstrey, Jolijn; Carlyon, Robert P.

    2013-01-01

    Summary Biologically salient sounds, including speech, are rarely heard in isolation. Our brains must therefore organize the input arising from multiple sources into separate “streams” and, in the case of speech, map the acoustic components of the target signal onto meaning. These auditory and linguistic processes have traditionally been considered to occur sequentially and are typically studied independently [1, 2]. However, evidence that streaming is modified or reset by attention [3], and that lexical knowledge can affect reports of speech sound identity [4, 5], suggests that higher-level factors may influence perceptual organization. In two experiments, listeners heard sequences of repeated words or acoustically matched nonwords. After several presentations, they reported that the initial /s/ sound in each syllable formed a separate stream; the percept then fluctuated between the streamed and fused states in a bistable manner. In addition to measuring these verbal transformations, we assessed streaming objectively by requiring listeners to detect occasional targets—syllables containing a gap after the initial /s/. Performance was better when streaming caused the syllables preceding the target to transform from words into nonwords, rather than from nonwords into words. Our results show that auditory stream formation is influenced not only by the acoustic properties of speech sounds, but also by higher-level processes involved in recognizing familiar words. PMID:23891107

  13. Pesticides' influence on wine fermentation.

    PubMed

    Caboni, Pierluigi; Cabras, Paolo

    2010-01-01

    Wine quality strongly depends on the grape quality. To obtain high-quality wines, it is necessary to process healthy grapes at the correct ripeness stage and for this reason the farmer has to be especially careful in the prevention of parasite attacks on the grapevine. The most common fungal diseases affecting grape quality are downy and powdery mildew (Plasmopara viticola and Uncinula necator), and gray mold (Botrytis cinerea). On the other hand, the most dangerous insects are the grape moth (Lobesia botrana), vine mealybug (Planococcus ficus), and the citrus mealybug (Planococcus citri). Farmers fight grape diseases and insects applying pesticides that can be found at harvest time on grapes. The persistence of pesticides depends on the chemical characteristic of the active ingredients as well as on photodegradation, thermodegradation, codistillation, and enzymatic degradation. The pesticide residues on grapes can be transferred to the must and this can influence the selection and development of yeast strains. Moreover, yeasts can also influence the levels of the pesticides in the wine by reducing or adsorbing them on lees. During the fermentative process, yeasts can cause the disappearance of pesticide residues by degradation or absorption at the end of the fermentation when yeasts are deposited as lees. In this chapter, we reviewed the effect of commonly used herbicides, insecticides, and fungicides on yeasts. We also studied the effect of alcoholic and malolactic fermentation on pesticide residues.

  14. Influence of convection on microstructure

    NASA Technical Reports Server (NTRS)

    Wilcox, William R.; Eisa, Gaber Faheem; Chandrasekhar, S.; Larrousse, Mark; Banan, Mohsen

    1988-01-01

    The influence was studied of convection during directional solidification on the resulting microstructure of eutectics, specifically lead/tin and manganese/bismuth. A theory was developed for the influence of convection on the microstructure of lamellar and fibrous eutectics, through the effect of convection on the concentration field in the melt in front of the growing eutectic. While the theory agrees with the experimental spin-up spin-down results, it predicts that the weak convection expected due to buoyancy will not produce a measurable change in eutectic microstructure. Thus, this theory does not explain the two fold decrease in MnBi fiber size and spacing observed when MnBi-Bi is solidified in space or on Earth with a magnetic field applied. Attention was turned to the morphology of the MnBi-Bi interface and to the generation of freezing rate fluctuations by convection. Decanting the melt during solidification of MnBi-Bi eutectic showed that the MnBi phase projects into the melt ahead of the Bi matrix. Temperature measurements in a Bi melt in the vertical Bridgman-Stockbarger configuration showed temperature variations of up to 25 C. Conclusions are drawn and discussed.

  15. Familial influences on adolescent smoking.

    PubMed

    Avenevoli, Shelli; Merikangas, Kathleen Ries

    2003-05-01

    The family unit is the primary source of transmission of basic social, cultural, genetic, and biological factors that may underlie individual differences in smoking. Existing information on the role of familial factors in tobacco use is characterized by two separate, but somewhat overlapping, lines of research: genetic epidemiological studies and risk-factor research. The present paper summarizes and evaluates studies assessing the association between adolescent smoking and parent and sibling smoking behaviors. A review of 87 studies reveals that methods are limited by a lack of standardized instruments, failure to measure important confounding and mediating factors, reliance on cross-sectional designs and the use of inconsistent definitions of tobacco-related behavior and assessment procedures. Moreover, there are no systematic family studies of the acquisition and continuation of smoking that have employed contemporary methodological standards for examining familial aggregation of tobacco behaviors among adolescents. Findings across studies show weak and inconsistent associations between parent and adolescent smoking; inconsistent findings may be attributed to methodological issues or associated factors that may complicate the relation between parent and adolescent smoking. Sibling and peer smoking show greater associations with adolescent smoking. Suggestions for future research include contemporary family studies that delineate meaningful phenotypes of tobacco use and prospective work on the later stages of tobacco use and the timing of the influence and valence of parent and family factors. Integration of the risk factor approach within the family study design may enrich both approaches to elucidate familial influences on smoking.

  16. Does quadriceps neuromuscular activation capability explain mobility function among older men and women?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Age-related impairment of neuromuscular activation has been shown to contribute to weakness in older adults. However, it is unclear to what extent impaired neuromuscular activation independently accounts for decline of mobility function. The hypothesis of this study is that capability to produce rap...

  17. Work capacity and metabolic and morphologic characteristics of the human quadriceps muscle in response to unloading

    NASA Technical Reports Server (NTRS)

    Berg, H. E.; Dudley, G. A.; Hather, B.; Tesch, P. A.

    1993-01-01

    The response of skeletal muscle to unweighting was studied in six healthy males who were subjected to four weeks of lowerlimb suspension. They performed three bouts of 30 consecutive maximal concentric knee extensions, before unloading and the day after (POST 1), 4 days after (POST 2) and 7 weeks after (REC) resumed weight-bearing. Peak torque of each contraction was recorded and work was calculated as the mean of the average peak torque for the three bouts and fatigability was measured as the decline in average peak torque over bouts. Needle biopsies were obtained from m. vastus lateralis of each limb before and at POST 1. Muscle fibre type composition and area, capillarity and the enzyme activities of citrate synthase (CS) and phosphofructokinase (PFK) were subsequently analysed. Mean average peak torque for the three bouts at POST1, POST2 and REC was reduced (P < 0.05) by 17, 13 and 7%, respectively. Fatigability was greater (P < 0.05) at POST2 than before unloading. Type I, IIA and IIB percentage, Type I and II area and capillaries per fibre of Type I and II did not change (P > 0.05) in response to unloading. The activity of CS, but not PFK, decreased (P < 0.05) after unloading. The weight-bearing limb showed no changes in the variables measured. The results of this study suggest that this human lowerlimb suspension model produces substantial impairments of work and oxidative capacity of skeletal muscle. The performance decrements are most likely induced by lack of weight-bearing.

  18. Voluntary activation level and muscle fiber recruitment of human quadriceps during lengthening contractions.

    PubMed

    Beltman, J G M; Sargeant, A J; van Mechelen, W; de Haan, A

    2004-08-01

    Voluntary activation levels during lengthening, isometric, and shortening contractions (angular velocity 60 degrees/s) were investigated by using electrical stimulation of the femoral nerve (triplet, 300 Hz) superimposed on maximal efforts. Recruitment of fiber populations was investigated by using the phosphocreatine-to-creatine ratio (PCr/Cr) of single characterized muscle fibers obtained from needle biopsies at rest and immediately after a series of 10 lengthening, isometric, and shortening contractions (1 s on/1 s off). Maximal voluntary torque was significantly higher during lengthening (270 +/- 55 N.m) compared with shortening contractions (199 +/- 47 N.m, P < 0.05) but was not different from isometric contractions (252 +/- 47 N.m). Isometric torque was higher than torque during shortening (P < 0.05). Voluntary activation level during maximal attempted lengthening contractions (79 +/- 8%) was significantly lower compared with isometric (93 +/- 5%) and shortening contractions (92 +/- 3%, P < 0.05). Mean PCr/Cr values of all fibers from all subjects at rest were 2.5 +/- 0.6, 2.0 +/- 0.7, and 2.0 +/- 0.7, respectively, for type I, IIa, and IIax fibers. After 10 contractions, the mean PCr/Cr values for grouped fiber populations (regardless of fiber type) were all significantly different from rest (1.3 +/- 0.2, 0.7 +/- 0.3, and 0.8 +/- 0.6 for lengthening, isometric, and shortening contractions, respectively; P < 0.05). The cumulative distributions of individual fiber populations after either contraction mode were significantly different from rest (P < 0.05). Curves after lengthening contractions were less shifted compared with curves from isometric and shortening contractions (P < 0.05), with a smaller shift for the type IIax compared with type I fibers in the lengthening contractions. The results indicate a reduced voluntary drive during lengthening contractions. PCr/Cr values of single fibers indicated a hierarchical order of recruitment of all fiber populations during maximal attempted lengthening contractions.

  19. Force control of quadriceps muscle is bilaterally impaired in subacute stroke.

    PubMed

    Chow, John W; Stokic, Dobrivoje S

    2011-11-01

    We tested the hypothesis that force variability and error during maintenance of submaximal isometric knee extension are greater in subacute stroke patients than in controls and are related to motor impairments. Contralesional (more-affected) and ipsilesional (less-affected) legs of 33 stroke patients with sufficiently high motor abilities (62 ± 13 yr, 16 ± 2 days postinjury) and the dominant leg of 20 controls (62 ± 10 yr) were tested in sitting position. After peak knee extension torque [maximum voluntary contraction (MVC)] was established, subjects maintained 10, 20, 30, and 50% of MVC as steady and accurate as possible for 10 s by matching voluntary force to the target level displayed on a monitor. Coefficient of variation (CV) and root-mean-square error (RMSE) were used to quantify force variability and error, respectively. The MVC was significantly smaller in the more-affected than less-affected leg, and both were significantly lower than in controls. The CV was significantly larger in the more-affected than less-affected leg at 20 and 50% MVC, whereas both were significantly larger compared with controls across all force levels. Both more-affected and less-affected legs of patients showed significantly greater RMSE than controls at 30 and 50% MVC. The CV and RMSE were not related to the Fugl-Meyer motor score or to the Rivermead Mobility Index. The CV negatively correlated with MVC in controls but only in the less-affected leg of patients. It is concluded that isometric knee extension strength and force control are bilaterally impaired soon after stroke but more so in the more-affected leg. Future studies should examine possible mechanisms and the evolution of these changes.

  20. “Slow walking with turns” increases quadriceps and erector spinae muscle activity

    PubMed Central

    Araki, Mayumi; Hatamoto, Yoichi; Higaki, Yasuki; Tanaka, Hiroaki

    2017-01-01

    [Purpose] To maintain an independent lifestyle, older adults should improve muscle strength and mass, or aerobic capacity. A new exercise pattern, called slow walking with turns, which incorporates turning as an extra load additional to walking. The purpose of this study was to measure oxygen consumption during exercise and muscle activity while turning. [Subjects and Methods] Recreationally active volunteers participated. The participants performed 20 turns per minute while walking back and forth over distances of 1.5 to 3.5 m. We measured oxygen consumption, heart rate, and rating of perceived exertion and performed electromyography during the exercise. [Results] The metabolic equivalents of the exercise were 4.0 ± 0.4 to 6.3 ± 4.0 Mets. Activity was significantly greater in the vastus medialis, vastus lateralis, and erector spinae during the turn phase of slow walking with turns than during the stance phase of treadmill walking. [Conclusion] These findings suggest that slow walking with turns may help to preserve the muscle strength and mass of the trunk and lower limbs that are needed to maintain an independent lifestyle. Slow walking can be performed easily by older people, and in slow walking with turns, the exercise intensity can be adjusted as required for each individual. PMID:28356623

  1. [Proteins influencing the blood coagulation].

    PubMed

    Alberio, Lorenzo

    2011-11-01

    This review describes some natural proteins, which can be employed, either as factor concentrates derived from human plasma or as recombinant drug, to modulate the coagulation system. I will address some biochemical characteristics and the physiological role of von Willebrand factor, the coagulation factors of the extrinsic and intrinsic pathways, and the physiological anticoagulant protein C. In addition, I will detail the pharmacological compounds, which are available for influencing or substituting the coagulation proteins: desmopressin (DDAVP), single coagulation factor concentrates, prothrombin complex concentrates, and protein C concentrate. In particular, I will address some treatment topics of general medical interest, such as the treatment of massive bleeding, the correction of the coagulopathy induced by vitamin K-antagonists in patients with cerebral haemorrhage, and of the coagulopathy of meningococcemia. Finally, I will describe some properties and practical clinical applications of the recombinant anticoagulans lepirudin and bivalirudin, which are derived from hirudin, the natural anticoagulant of the medical leech.

  2. Human diffusion and city influence

    PubMed Central

    Lenormand, Maxime; Gonçalves, Bruno; Tugores, Antònia; Ramasco, José J.

    2015-01-01

    Cities are characterized by concentrating population, economic activity and services. However, not all cities are equal and a natural hierarchy at local, regional or global scales spontaneously emerges. In this work, we introduce a method to quantify city influence using geolocated tweets to characterize human mobility. Rome and Paris appear consistently as the cities attracting most diverse visitors. The ratio between locals and non-local visitors turns out to be fundamental for a city to truly be global. Focusing only on urban residents' mobility flows, a city-to-city network can be constructed. This network allows us to analyse centrality measures at different scales. New York and London play a central role on the global scale, while urban rankings suffer substantial changes if the focus is set at a regional level. PMID:26179991

  3. Atmospheric composition - Influence of biology

    NASA Technical Reports Server (NTRS)

    Mcelroy, M. B.

    1983-01-01

    The variability of atmospheric constituents influenced by biological organisms over various time scales is examined, together with the human contribution to atmospheric sulfur. The biogeochemistry of nitrogen is discussed, with an emphasis on N2O, NO, and microbially mediated reactions in soil and water. Carbon species are bound up mainly in sediments and the deep ocean, but human activities involving combustion may cause a doubling of the atmospheric levels of CO2 in the near future, which could produce a general low-level atmospheric warming. Longer term measurements are required to assess the effects of CH4 augmentation in the atmosphere through fuel combustion. Coal burning effectively doubles the amount of SO2 produced by natural sources, and reduces the pH of rainwater, thus posing hazards to fish, plankton, and mollusc life.

  4. How do stereotypes influence choice?

    PubMed

    Chaxel, Anne-Sophie

    2015-05-01

    In the study reported here, I tracked one process through which stereotypes affect choice. The Implicit Association Test (IAT) and a measurement of predecisional information distortion were used to assess the influence of the association between male gender and career on the evaluation of information related to the job performance of stereotypical targets (male) and nonstereotypical targets (female). When the IAT revealed a strong association between male gender and career and the installed leader in the choice process was a stereotypical target, decision makers supported the leader with more proleader distortion; when the IAT revealed a strong association between male gender and career and the installed leader in the choice process was a nonstereotypical target, decision makers supported the trailer with less antitrailer distortion. A stronger association between male gender and career therefore resulted in an upward shift of the evaluation related to the stereotypical target (both as a trailer and a leader), which subsequently biased choice.

  5. Information-based physics, influence, and forces

    NASA Astrophysics Data System (ADS)

    Walsh, James Lyons; Knuth, Kevin H.

    2015-01-01

    In recent works, Knuth and Bahreyni have demonstrated that the concepts of space and time are emergent in a coarse-grained model of direct particle-particle influence. In addition, Knuth demonstrated that observer-made inferences regarding the free particle, which is defined as a particle that influences others, but is not itself influenced, result in a situation identical to the Feynman checkerboard model of the Dirac equation. This suggests that the same theoretical framework that gives rise to an emergent spacetime is consistent with quantum mechanics. In this paper, we begin to explore the effect of influence on the emergent properties of a particle. This initial study suggests that when a particle is influenced, it is interpreted as accelerating in a manner consistent with special relativity implying that, at least in this situation, influence can be conceived of as a force.

  6. Information-based physics, influence, and forces

    SciTech Connect

    Walsh, James Lyons; Knuth, Kevin H.

    2015-01-13

    In recent works, Knuth and Bahreyni have demonstrated that the concepts of space and time are emergent in a coarse-grained model of direct particle-particle influence. In addition, Knuth demonstrated that observer-made inferences regarding the free particle, which is defined as a particle that influences others, but is not itself influenced, result in a situation identical to the Feynman checkerboard model of the Dirac equation. This suggests that the same theoretical framework that gives rise to an emergent spacetime is consistent with quantum mechanics. In this paper, we begin to explore the effect of influence on the emergent properties of a particle. This initial study suggests that when a particle is influenced, it is interpreted as accelerating in a manner consistent with special relativity implying that, at least in this situation, influence can be conceived of as a force.

  7. Influence of convection on microstructure

    NASA Technical Reports Server (NTRS)

    Wilcox, William R.; Regel, Liya L.

    1992-01-01

    The primary motivation for this research has been to determine the cause for space processing altering the microstructure of some eutectics, especially the MnBi-Bi eutectic. Prior experimental research at Grumman and here showed that the microstructure of MnBi-Bi eutectic is twice as fine when solidified in space or in a magnetic field, is uninfluenced by interfacial temperature gradient, adjusts very quickly to changes in freezing rate, and becomes coarser when spin-up/spin-down (accelerated crucible rotation technique) is used during solidification. Theoretical work at Clarkson predicted that buoyancy driven convection on earth could not account for the two fold change in fiber spacing caused by solidification in space. However, a lamellar structure with a planar interface was assumed, and the Soret effect was not included in the analysis. Experimental work at Clarkson showed that the interface is not planar, and that MnBi fibers project out in front of the Bi matrix on the order of one fiber diameter. Originally four primary hypotheses were to be tested under this current grant: (1) a fibrous microstructure is much more sensitive to convection than a lamellar microstructure, which was assumed in our prior theoretical treatment; (2) an interface with one phase projecting out into the melt is much more sensitive to convection than a planar interface, which was assumed in our prior theoretical treatment; (3) the Soret effect is much more important in the absence of convection and has a sufficiently large influence on microstructure that its action can explain the flight results; and (4) the microstructure is much more sensitive to convection when the composition of the bulk melt is off eutectic. As reported previously, we have learned that while a fibrous microstructure and a non-planar interface are more sensitive to convection than a lamellar microstructure with a planar interface, the influence of convection remains too small to explain the flight and magnetic

  8. Sociocultural Influences on Psychosocial Adjustment in Antarctica

    DTIC Science & Technology

    1985-12-01

    stage, the group is open, consisting of individuals who are removed from the direct influence of their accustomed sociocultural framework and are forced... groups , the harsh environment, and the prolonged isola- tion from outside contact. The degree of stress, however, is influenced by different...interaction of these influences . In parti- cular, as the heterogeneity of social group increases so does the potential for interper- sonal as well as

  9. [Erasmian influences among renaissance physicians].

    PubMed

    de Micheli, Alfredo

    2002-01-01

    The fundamental aspects of Erasmus's ethic humanism consisted of ideals of universal peace and tolerance. These ideals are exposed in the great works of his maturity Colloquia and Adagia read and meditated on by renaissance physicians in England, Spain, Germany, Italy, and also in the New Spain. Erasmus's readers were learned and numerous. Among his pupils and supporters in Spain were humanist physicians of Madrid such as Doctors Suárez and Juan de Jarava. Other supporters were in the group of the Sevillian physicians and naturalists. Among the Erasmist physicians, residing in other regions was doctor Andrés Laguna, who translated into Spanish the Dioscorides treatise on medical botany. Many physicians living in New Spain owned copies of Erasmian works, such as Doctors Pedro López (the second) and Juan de la Fuente, who was in charge of the first medical chair at the University of Mexico. The protophysician Francisco Hernández, in response to a petition of Archbishop Pedro Moya de Contreras, wrote a Christian catechism of Erasmian influence, destined for humanists in NewSpain. As asserted by Johan Huizinga, Erasmus was the sole humanist who really wrote for everyone, i.e. for all cultured people.

  10. Factors influencing healthcare service quality

    PubMed Central

    Mosadeghrad, Ali Mohammad

    2014-01-01

    Background: The main purpose of this study was to identify factors that influence healthcare quality in the Iranian context. Methods: Exploratory in-depth individual and focus group interviews were conducted with 222 healthcare stakeholders including healthcare providers, managers, policy-makers, and payers to identify factors affecting the quality of healthcare services provided in Iranian healthcare organisations. Results: Quality in healthcare is a production of cooperation between the patient and the healthcare provider in a supportive environment. Personal factors of the provider and the patient, and factors pertaining to the healthcare organisation, healthcare system, and the broader environment affect healthcare service quality. Healthcare quality can be improved by supportive visionary leadership, proper planning, education and training, availability of resources, effective management of resources, employees and processes, and collaboration and cooperation among providers. Conclusion: This article contributes to healthcare theory and practice by developing a conceptual framework that provides policy-makers and managers a practical understanding of factors that affect healthcare service quality. PMID:25114946

  11. Factors influencing breath ammonia determination.

    PubMed

    Solga, Steven F; Mudalel, Matthew; Spacek, Lisa A; Lewicki, Rafal; Tittel, Frank; Loccioni, Claudio; Russo, Adolfo; Risby, Terence H

    2013-09-01

    Amongst volatile compounds (VCs) present in exhaled breath, ammonia has held great promise and yet it has confounded researchers due to its inherent reactivity. Herein we have evaluated various factors in both breath instrumentation and the breath collection process in an effort to reduce variability. We found that the temperature of breath sampler and breath sensor, mouth rinse pH, and mode of breathing to be important factors. The influence of the rinses is heavily dependent upon the pH of the rinse. The basic rinse (pH 8.0) caused a mean increase of the ammonia concentration by 410 ± 221 ppb. The neutral rinse (pH 7.0), slightly acidic rinse (pH 5.8), and acidic rinse (pH 2.5) caused a mean decrease of the ammonia concentration by 498 ± 355 ppb, 527 ± 198 ppb, and 596 ± 385 ppb, respectively. Mode of breathing (mouth-open versus mouth-closed) demonstrated itself to have a large impact on the rate of recovery of breath ammonia after a water rinse. Within 30 min, breath ammonia returned to 98 ± 16% that of the baseline with mouth open breathing, while mouth closed breathing allowed breath ammonia to return to 53 ± 14% of baseline. These results contribute to a growing body of literature that will improve reproducibly in ammonia and other VCs.

  12. Wind-influenced projectile motion

    NASA Astrophysics Data System (ADS)

    Bernardo, Reginald Christian; Perico Esguerra, Jose; Day Vallejos, Jazmine; Jerard Canda, Jeff

    2015-03-01

    We solved the wind-influenced projectile motion problem with the same initial and final heights and obtained exact analytical expressions for the shape of the trajectory, range, maximum height, time of flight, time of ascent, and time of descent with the help of the Lambert W function. It turns out that the range and maximum horizontal displacement are not always equal. When launched at a critical angle, the projectile will return to its starting position. It turns out that a launch angle of 90° maximizes the time of flight, time of ascent, time of descent, and maximum height and that the launch angle corresponding to maximum range can be obtained by solving a transcendental equation. Finally, we expressed in a parametric equation the locus of points corresponding to maximum heights for projectiles launched from the ground with the same initial speed in all directions. We used the results to estimate how much a moderate wind can modify a golf ball’s range and suggested other possible applications.

  13. Solar Influence on Future Climate

    NASA Astrophysics Data System (ADS)

    Arsenovic, Pavle; Stenke, Andrea; Rozanov, Eugene; Peter, Thomas

    2015-04-01

    Global warming is one of the main threats to mankind. There is growing evidence that anthropogenic greenhouse gases have become the dominant factor, however natural factors such as solar variability cannot be neglected. Sun is a variable star; its activity varies in regular 11-years solar cycles. Longer periods of decreased solar activity are called Grand Solar Minima, which have stronger impact on terrestrial climate. Another natural factor related with solar activity are energetic particles. They can ionize neutral molecules in upper atmosphere and produce NOx and HOx which deplete ozone. We investigate the effect of proposed Grand Solar Minimum in 21st and 22nd century on terrestrial climate and ozone layer. The simulations are performed with different solar forcing scenarios for period of 200 years (2000-2200) using global chemistry-climate model coupled with ocean model (SOCOL-MPIOM). We also deal with problem of representation of middle range energy electrons (30-300 keV) in the model and investigation of their influence on climate.

  14. Deformation parameters influencing prepreg tack

    SciTech Connect

    Ahn, K.J.; Seferis, J.C. ); Pelton, T.; Wilhelm, M. )

    1992-01-01

    A compression to tension apparatus and a methodology capable of measuring prepreg tack have been analyzed in detail in order to establish fundamental material and operating characteristics. Both intrinsic and extrinsic parameters influencing prepreg tack were identified and analyzed using commercially available carbon fiber/epoxy prepregs and mechanical testing equipment. Two different factors, (1) contact (or wetting) area of adjacent prepreg plies and (2) viscoelastic properties of the prepreg, were found to control prepreg tack. At low temperatures, contact area was the main deformation controlling step, while at high temperatures, the viscoelastic property of the prepreg was found to be dominant. Both interlaminar and intralaminar deformations were observed depending on the prepreg systems examined as well as the operating conditions of the test. In addition, hold time, hold pressure, loading rate, resin content, and out-time were also found to affect prepreg tack. Energy of separation, which may be viewed as a descriptor of prepreg tack, was observed to increase with increasing hold time, hold pressure, and loading rate. Energy of separation also showed a maximum value at a specific resin content for a specific prepreg system, while it decreased with increasing prepreg out-time due to prepreg surface characteristic change rather than bulk physical aging. Conclusively, it was observed that prepreg tack must be viewed as an extrinsic, bulk, but surface-sensitive, viscoelastic property which depends on material as well as operating conditions.

  15. Prenatal meditation influences infant behaviors.

    PubMed

    Chan, Ka Po

    2014-11-01

    Meditation is important in facilitating health. Pregnancy health has been shown to have significant consequences for infant behaviors. In view of limited studies on meditation and infant temperament, this study aims to explore the effects of prenatal meditation on these aspects. The conceptual framework was based on the postulation of positive relationships between prenatal meditation and infant health. A randomized control quantitative study was carried out at Obstetric Unit, Queen Elizabeth Hospital in Hong Kong. 64 pregnant Chinese women were recruited for intervention and 59 were for control. Outcome measures were cord blood cortisol, infant salivary cortisol, and Carey Infant Temperament Questionnaire. Cord blood cortisol level of babies was higher in the intervention group (p<0.01) indicates positive health status of the newborns verifies that prenatal meditation can influence fetal health. Carey Infant Temperament Questionnaire showed that the infants of intervention group have better temperament (p<0.05) at fifth month reflects the importance of prenatal meditation in relation to child health. Present study concludes the positive effects of prenatal meditation on infant behaviors and recommends that pregnancy care providers should provide prenatal meditation to pregnant women.

  16. Influence of convection on microstructure

    NASA Technical Reports Server (NTRS)

    Wilcox, William R.; Caram, Rubens; Mohanty, A. P.; Seth, Jayshree

    1990-01-01

    In eutectic growth, as the solid phases grow they reject atoms to the liquid. This results in a variation of melt composition along the solid/liquid interface. In the past, mass transfer in eutectic solidification, in the absence of convection, was considered to be governed only by the diffusion induced by compositional gradients. However, mass transfer can also be generated by a temperature gradient. This is called thermotransport, thermomigration, thermal diffusion or the Soret effect. A theoretical model of the influence of the Soret effect on the growth of eutectic alloys is presented. A differential equation describing the compositional field near the interface during unidirectional solidification of a binary eutectic alloy was formulated by including the contributions of both compositional and thermal gradients in the liquid. A steady-state solution of the differential equation was obtained by applying appropriate boundary conditions and accounting for heat flow in the melt. Following that, the average interfacial composition was converted to a variation of undercooling at the interface, and consequently to microstructural parameters. The results obtained show that thermotransport can, under certain circumstances, be a parameter of paramount importance.

  17. SURFACE CHEMISTRY INFLUENCE IMPLANT BIOCOMPATIBILITY

    PubMed Central

    Thevenot, Paul; Hu, Wenjing; Tang, Liping

    2011-01-01

    Implantable medical devices are increasingly important in the practice of modern medicine. Unfortunately, almost all medical devices suffer to a different extent from adverse reactions, including inflammation, fibrosis, thrombosis and infection. To improve the safety and function of many types of medical implants, a major need exists for development of materials that evoked desired tissue responses. Because implant-associated protein adsorption and conformational changes thereafter have been shown to promote immune reactions, rigorous research efforts have been emphasized on the engineering of surface property (physical and chemical characteristics) to reduce protein adsorption and cell interactions and subsequently improve implant biocompatibility. This brief review is aimed to summarize the past efforts and our recent knowledge about the influence of surface functionality on protein:cell:biomaterial interactions. It is our belief that detailed understandings of bioactivity of surface functionality provide an easy, economic, and specific approach for the future rational design of implantable medical devices with desired tissue reactivity and, hopefully, wound healing capability. PMID:18393890

  18. Factors influencing perceived angular velocity

    NASA Technical Reports Server (NTRS)

    Kaiser, Mary K.; Calderone, Jack B.

    1991-01-01

    Angular velocity perception is examined for rotations both in depth and in the image plane and the influence of several object properties on this motion parameter is explored. Two major object properties are considered, namely, texture density which determines the rate of edge transitions for rotations in depth, i.e., the number of texture elements that pass an object's boundary per unit of time, and object size which determines the tangential linear velocities and 2D image velocities of texture elements for a given angular velocity. Results of experiments show that edge-transition rate biased angular velocity estimates only when edges were highly salient. Element velocities had an impact on perceived angular velocity; this bias was associated with 2D image velocity rather than 3D tangential velocity. Despite these biases judgements were most strongly determined by the true angular velocity. Sensitivity to this higher order motion parameter appeared to be good for rotations both in depth (y-axis) and parallel to the line of sight (z-axis).

  19. Influence of vibration on delayed onset of muscle soreness following eccentric exercise

    PubMed Central

    Bakhtiary, Amir H; Safavi‐Farokhi, Ziaeddin; Aminian‐Far, Atefeh

    2007-01-01

    Delayed onset muscle soreness (DOMS), which may occur after eccentric exercise, may cause some reduction in ability in sport activities. For this reason, several studies have been designed on preventing and controlling DOMS. As vibration training (VT) may improve muscle performance, we designed this study to investigate the effect of VT on controlling and preventing DOMS after eccentric exercise. Methods Fifty healthy non‐athletic volunteers were assigned randomly into two experimental, VT (n = 25) and non‐VT (n = 25) groups. A vibrator was used to apply 50 Hz vibration on the left and right quadriceps, hamstring and calf muscles for 1 min in the VT group, while no vibration was applied in the non‐VT group. Then, both groups walked downhill on a 10° declined treadmill at a speed of 4 km/hour. The measurements included the isometric maximum voluntary contraction force (IMVC) of left and right quadriceps muscles, pressure pain threshold (PPT) 5, 10 and 15 cm above the patella and mid‐line of the calf muscles of both lower limbs before and the day after treadmill walking. After 24 hours, the serum levels of creatine‐kinase (CK), and DOMS level by visual analogue scale were measured. Results The results showed decreased IMVC force (P = 0.006), reduced PPT (P = 0.0001) and significantly increased mean of DOMS and CK levels in the non‐VT group, compared to the VT group (P = 0.001). Conclusion A comparison by experimental groups indicates that VT before eccentric exercise may prevent and control DOMS. Further studies should be undertaken to ascertain the stability and effectiveness of VT in athletics. PMID:17138635

  20. Can tides influence volcanic eruptions?

    NASA Astrophysics Data System (ADS)

    Girona, T.; Huber, C.

    2015-12-01

    The possibility that the Moon-Sun gravitational force can affect terrestrial volcanoes and trigger eruptions is a controversial issue that has been proposed since ancient times, and that has been widely debated during the last century. The controversy arises mainly from two reasons. First, the days of initiation of eruptions are not well known for many volcanoes, and thus a robust statistical comparison with tidal cycles cannot be performed for many of them. Second, the stress changes induced by tides in the upper crust are very small (10-3 MPa) compared to the tensile strength of rocks (~ 10-1-10 MPa), and hence the mechanism by which tidal stresses might trigger eruptions is unclear. In this study, we address these issues for persistently degassing volcanoes, as they erupt frequently and thus the initiation time of a significant number of eruptions (>30) is well known in several cases (9). In particular, we find that the occurrence of eruptions within ±2 days from neap tides (first and third quarter moon) is lower than 34% (e.g., 29% for Etna, Italy; 28% for Merapi, Indonesia), which is the value expected if eruptions occur randomly with no external influence. To understand this preference for erupting far away from neap tides, we have developed a new lumped-parameter model that accounts for the deformation of magma reservoirs, a partially open conduit, and a gas layer where bubbles accumulate beneath volcanic craters before being released. We demonstrate that this system reservoir-conduit-gas layer acts as an amplifier of the tidal stresses, such that, when a volcano approaches to a critical state, the gas overpressure beneath the crater can reach up to several MPa more during a spring tide (full and new moon) than during a neap tide. This amplification mechanism can explain why active volcanoes are sensitive to the moon cycles.

  1. Factors that Influence Participation in Online Learning

    ERIC Educational Resources Information Center

    Vonderwell, Selma; Zachariah, Sajit

    2005-01-01

    This study explored what factors influenced learner participation in two sections of a graduate online course at a Midwestern university. Findings indicated that online learner participation and patterns of participation are influenced by the following factors: technology and interface characteristics, content area experience, student roles and…

  2. Hannelore Wass: Professional Influences and Legacies.

    PubMed

    Corr, Charles A

    2015-01-01

    This article offers a reflection on the professional influence of Dr. Hannelore Wass on the author's introduction to and work in the field of death, dying, and bereavement. At the same time, it also offers comments on her broader influence on and legacies left to others who work in this field.

  3. American Influence on Okinawan Culture before 1972.

    ERIC Educational Resources Information Center

    Trafton, Terry

    The Ryukyu Islands form a chain stretching from the southernmost point of mainland Japan to the northern tip of Taiwan. The largest and most important of these islands is Okinawa. This paper documents the influence of other nations and cultures upon the Okinawan culture, and focuses upon U.S. cultural influence. In the mid-nineteenth century,…

  4. Geodesics and Acceleration in Influence Theory

    NASA Astrophysics Data System (ADS)

    Walsh, James; Knuth, Kevin

    Influence theory is concerned with a foundational approach where it is assumed that particles influence one another in a discrete one-to-one fashion. This results in a partially ordered set of influence events, called the influence network, where particles are represented by totally ordered chains of events. Information physics considers physical laws to result from consistent quantification of physical phenomena. Knuth and Bahreyni (2014) demonstrated that the mathematics of spacetime emerges from consistent quantification of influence events by embedded coordinated observers. Knuth (2014) showed that in 1 +1 dimensions observer-based predictions about a free (uninfluenced) particle result in the Dirac equation. Here, we show that when a particle in 1 +1 dimensions is influenced, it is uniquely and consistently described in terms of relativistic acceleration for constant rate of influence and in general obeys equations of the form of the geodesic equations of general relativity. This suggests that Influence Theory can also account for forces (like gravity), which give rise to well-known relativistic effects such as time dilation.

  5. Substitute or Complement?: Spousal Influence on Volunteering

    ERIC Educational Resources Information Center

    Rotolo, Thomas; Wilson, John

    2006-01-01

    Social scientists have documented the influence of family statuses on volunteering, ignoring intrafamily effects. Using newly issued data from the Current Population Survey on the volunteer behavior of 19,626 American couples, we test two competing theories concerning spousal influences on volunteering. Substitution theory predicts that spouses…

  6. How Friends Influence Adolescents' Adjustment to School.

    ERIC Educational Resources Information Center

    Berndt, Thomas J.; Keefe, Keunho

    A short-term longitudinal study investigated theoretical perspectives on friends' influences and compared the influence of a student's closest friend with that of several close friends. Participants were 297 seventh and eighth graders in junior high schools in small towns or rural areas adjacent to a medium-sized city. Measures obtained in the…

  7. Relative Influence of Professional Counseling Journals

    ERIC Educational Resources Information Center

    Fernando, Delini M.; Barrio Minton, Casey A.

    2011-01-01

    The authors used social network analysis of citation data to study the flow of information and relative influence of 17 professional counseling journals. Although the "Journal of Counseling & Development" ranked very highly in all measures of journal influence, several division journals emerged as key players in the flow of information within the…

  8. Natal Influences and Twin Differences: Draft.

    ERIC Educational Resources Information Center

    Van den Daele, Leland D.

    1972-01-01

    A classification of natal influences is proposed with a model of their operation. Natal influences affect maternal capacity, maternal load, and maternal efficiency. Since maternal load is increased in twin pregnancy, results of twin studies must be generalized with caution. The method of co-twin control is exemplified by examination of a small…

  9. Avenues of Influence: Cross-Cultural Implications

    DTIC Science & Technology

    2014-04-01

    DoD) Intelligence, Surveillance, and Reconnaissance (ISR) community with knowledge of mechanisms that explain why some factors can be influentially...supports the Intelligence Community (IC) efforts to understand, forecast, and influence actor behavior. The growing importance of behavioral influences...This in-house effort leveraged multiple resources: Established professional relationships within the international military research community

  10. Genetic and Environmental Influences on Adolescent Attachment

    ERIC Educational Resources Information Center

    Fearon, Pasco; Shmueli-Goetz, Yael; Viding, Essi; Fonagy, Peter; Plomin, Robert

    2014-01-01

    Background: Twin studies consistently point to limited genetic influence on attachment security in the infancy period, but no study has examined whether this remains the case in later development. This study presents the findings from a twin study examining the relative importance of genetic and environmental influences on attachment in…

  11. The Influence of Poverty on Achievement

    ERIC Educational Resources Information Center

    Tienken, Christopher H.

    2012-01-01

    Without a doubt, poverty has a negative influence on student achievement, especially when achievement is measured by state-mandated standardized tests. However, some bureaucrats, such as state commissioners of education and even state governors, continue to downplay the influence of poverty on student achievement. New Jersey's Governor Chris…

  12. Sociocultural Influences on Brazilian Children's Drawings.

    ERIC Educational Resources Information Center

    Stokrocki, Mary

    2000-01-01

    Reports on insights about sociocultural influences on Brazilian children's drawings, using visual anthropology to examine children's drawings that depicted what they like to do. Discusses visual anthropology, provides information on Brazilian educational influences, and presents the context and findings of the study. (CMK)

  13. Interpersonal Influence in Cross-Cultural Interactions

    DTIC Science & Technology

    2010-10-01

    RTO-MP-HFM-202 7 - 1 Interpersonal Influence in Cross-Cultural Interactions D.A. van Hemert TNO Defence, Security and Safety Human...and the target audiences could have a negative impact upon influencing activities. To achieve effective interpersonal interactions in cross-cultural...military operations, insight is needed into determinants of successful interpersonal interactions. This paper discusses a generic theoretical

  14. Perceptions of Advertising Influence on Broadcast News.

    ERIC Educational Resources Information Center

    Brown, Hubert W.; Barnes, Beth E.

    2001-01-01

    Finds that while students (studying broadcast journalism or advertising) and practitioners (station news directors and agency media directors) were in agreement on the majority of opinion statements discussing advertising's influence on broadcast news content, except students were less bothered by advertising's influence on news content than were…

  15. The Influence of Notches Under Static Stress

    NASA Technical Reports Server (NTRS)

    Matthaes, K

    1938-01-01

    From the described experiments it is seen that notches are a potential source of strength decrease even under static stress, which the designer must take into consideration. Section I is a general treatment of notch influence under the various types of stresses. Section II treats the influence of notches in thin sheet as is used in airplane construction.

  16. Nurses’ policy influence: A concept analysis

    PubMed Central

    Arabi, Akram; Rafii, Forough; Cheraghi, Mohammad Ali; Ghiyasvandian, Shahrzad

    2014-01-01

    Background: Nurses’ influence on health policy protects the quality of care by access to required recourses and opportunities. This is a new and important concept for nursing; however, research studies on policy influence of nurses in health care sector are lacking a basic conceptual understanding of what this concept represents. The aim of this paper is to clarify the concept of nurses’ policy influence and to propose the definition of this concept, considering the context of Iran. Materials and Methods: The eight stages of Walker and Avant approach was used to guide this concept analysis. Various databases and internet engines were searched to find all related information about the concept. Textbooks were also searched manually. English language literature reports published between 1990 and 2012 were reviewed. Results: Based on the analysis undertaken, nurses’ policy influence is nurses’ ability in influencing decisions and affairs related to health through political knowledge, effective communication, and collaboration with other members of the health team, which results in the improvement of nurses’ job environment and increases patient outcomes. This is a dynamic process situated on a spectrum and is accompanied with nurses’ knowledge, competency, power, and advocacy, and also their ability to change. Conclusions: Nurses have individual views on health care issues and influence health care policies in different ways. With a common understanding of nurses’ policy influence as a concept, nurses will recognize the importance of policy making in the health sector and their influence on this process and also on patients’ outcomes. PMID:24949073

  17. Influence analysis in quantitative trait loci detection

    PubMed Central

    Dou, Xiaoling; Kuriki, Satoshi; Maeno, Akiteru; Takada, Toyoyuki; Shiroishi, Toshihiko

    2014-01-01

    This paper presents systematic methods for the detection of influential individuals that affect the log odds (LOD) score curve. We derive general formulas of influence functions for profile likelihoods and introduce them into two standard quantitative trait locus detection methods—the interval mapping method and single marker analysis. Besides influence analysis on specific LOD scores, we also develop influence analysis methods on the shape of the LOD score curves. A simulation-based method is proposed to assess the significance of the influence of the individuals. These methods are shown useful in the influence analysis of a real dataset of an experimental population from an F2 mouse cross. By receiver operating characteristic analysis, we confirm that the proposed methods show better performance than existing diagnostics. PMID:24740424

  18. Brain Substrates of Recovery from Misleading Influence

    PubMed Central

    Dudai, Yadin; Dolan, Raymond J.; Sharot, Tali

    2014-01-01

    Humans are strongly influenced by their environment, a dependence that can lead to errors in judgment. Although a rich literature describes how people are influenced by others, little is known regarding the factors that predict subsequent rectification of misleading influence. Using a mediation model in combination with brain imaging, we propose a model for the correction of misinformation. Specifically, our data suggest that amygdala modulation of hippocampal mnemonic representations, during the time of misleading social influence, is associated with reduced subsequent anterior–lateral prefrontal cortex activity that reflects correction. These findings illuminate the process by which erroneous beliefs are, or fail to be, rectified and highlight how past influence constrains subsequent correction. PMID:24899698

  19. Open to Influence: What Counts as Academic Influence in Scholarly Networked "Twitter" Participation

    ERIC Educational Resources Information Center

    Stewart, Bonnie

    2015-01-01

    Within the academy, signals of a scholar's academic influence are made manifest in indices like the "h"-index, which rank output. In open scholarly networks, however, signals of influence are less codified, and the ways in which they are enacted and understood have yet to be articulated. Yet the influence scholars cultivate in open…

  20. [7 MHz real-time sonography of the skeletal musculature in Duchenne muscular dystrophy].

    PubMed

    Forst, R; Casser, H R

    1985-12-01

    The lumbar paravertebral musculature, the M. quadriceps femoris and M. triceps surae of boys suffering from Duchenne's muscular dystrophy of different clinical progression, were examined via sonography. The sonographic incisions were made at fixed levels. The sonographic findings were compared with those of healthy boys. The sonographic findings showed - depending on the clinical stage of Duchenne's muscular dystrophy - typical reflex patterns of different intensity determined by lipomatosis and fibrosis of the skeletal musculature, correlating with the clinical stage, and hence musclesonography is an important diagnostic element in the observation of the course and in therapy planning in Duchenne's muscular dystrophy. The 7-MHz transducer has an advantage over the low-frequency transducers mostly in use, because the image quality is substantially superior.

  1. Protein oxidation during frozen storage and subsequent processing of different beef muscles.

    PubMed

    Utrera, Mariana; Parra, Vita; Estévez, Mario

    2014-02-01

    This study examined the relationship between protein and lipid oxidation and the impairment of the water holding capacity (WHC), redness and instrumental hardness occurring during 20 weeks of frozen storage (-18 °C) and subsequent processing (cooking, chilled storage) of psoas major, quadriceps femoris and longissimus dorsi beef patties. Patties were analyzed at sampling times upon thawing (weeks 0, 4, 8, 12 and 20) for lipid (TBARS, hexanal) and protein oxidation products (α-aminoadipic and γ-glutamic semialdehydes, α-aminoadipic acid, Schiff bases). A significant impact of frozen storage on protein oxidation was found, which occurred concomitantly with a loss of WHC, redness and significant changes in the hardness of cooked patties. Heme-iron, endogenous antioxidant enzymes and to a lower extent, fatty acid composition, played a role in the oxidative stability of patties. Plausible mechanisms by which particular protein oxidation changes may lead to loss of WHC and impaired quality traits were discussed.

  2. Quercetin dietary supplementation of fattening lambs at 0.2% rate reduces discolouration and microbial growth in meat during refrigerated storage.

    PubMed

    Andrés, S; Tejido, M L; Bodas, R; Morán, L; Prieto, N; Blanco, C; Giráldez, F J

    2013-02-01

    Thirty-two Merino lambs fed barley straw and a concentrate formulated either with palm oil (CTRL group) plus quercetin (QCT group) or flaxseed (FS group) plus quercetin (FS-QCT group) were used to assess the effects of this flavonoid on meat quality attributes. The animals were slaughtered after being fed for at least 5 weeks with the experimental diets. Chemical composition of longissimus thoracis (LT) muscle was not different among treatments. The longissimus lumborum (LL) samples of QCT and FS-QCT groups revealed lower discolouration (hue angle) when compared to the CTRL and FS lambs (P<0.05), whereas extract release volume (ERV) and microbiological data jointly suggest that flaxseed and quercetin may reduce the growth of microbial populations responsible for meat spoilage in quadriceps femoris (QF).

  3. The presence of disease-associated prion protein in skeletal muscle of cattle infected with classical bovine spongiform encephalopathy.

    PubMed

    Okada, Hiroyuki; Miyazawa, Kohtaro; Fukuda, Shigeo; Iwamaru, Yoshifumi; Imamura, Morikazu; Masujin, Kentaro; Matsuura, Yuichi; Fujii, Takashi; Fujii, Kei; Kageyama, Soichi; Yoshioka, Miyako; Murayama, Yuichi; Yokoyama, Takashi

    2014-01-01

    The aim of this study was to investigate the presence of disease-associated prion protein (PrP(Sc)) in the skeletal muscle of cattle infected with classical bovine spongiform encephalopathy (C-BSE). The study was carried out systematically in 12 different muscle samples from 43 (3 field and 40 experimental) cases of C-BSE; however, muscle spindles were not available in many of these cases. Therefore, analysis became restricted to a total of 31 muscles in 23 cattle. Even after this restriction, low levels of PrP(Sc) were detected in the muscle spindles of the masseter, intercostal, triceps brachii, psoas major, quadriceps femoris and semitendinosus muscles from 3 field and 6 experimental clinical-stage cases. The present data indicate that small amounts of PrP(Sc) are detectable by immunohistochemistry in the skeletal muscles of animals terminally affected with C-BSE.

  4. Chemical and physical characteristics of lamb meat related to crossbreeding of Romanov ewes with Suffolk and Charollais sires.

    PubMed

    Kuchtík, Jan; Zapletal, David; Šustová, Květoslava

    2012-02-01

    The aim was to evaluate the effects of crossbreeding Romanov (RO) ewes with Suffolk (SF) and Charollais (CH) sires on the chemicophysical characteristics and FA profile of the Quadriceps femoris muscle (QFM) in lambs fattened under organic conditions. The experimental animals were male lamb twins of two different crossbreds; CH 50 RO 50 and SF 50 RO 50. Lambs were slaughtered at an average live weight of 31kg. CH 50 RO 50 displayed higher contents of dry matter and intramuscular fat of the QFM. A lower pH value of CH 50 RO 50 was reflected in an increase of WHC. Meat of SF 50 RO 50 lambs had more lightness (L*) and yellowness (b*). The CH 50 RO 50 genotype showed a significantly higher proportion of C18:3n-3cis and n-3 PUFA than the SF 50 RO 50 genotype. The genotype also affected the Δ(9)-desaturase (16) index.

  5. Differences in Gait Characteristics of Patients with Lumbar Spinal Canal Stenosis (L4 Radiculopathy) and Those with Osteoarthritis of the Hip.

    PubMed

    Yokogawa, Noriaki; Toribatake, Yasumitsu; Murakami, Hideki; Hayashi, Hiroyuki; Yoneyama, Takeshi; Watanabe, Tetsuyou; Tsuchiya, Hiroyuki

    2015-01-01

    It is important to differentially diagnose thigh pain from lumbar spinal stenosis (particularly lumbar fourth nerve root radiculopathy) and osteoarthritis of the hip. In this study, using a treadmill and a motion analysis method, gait characteristics were compared between these conditions. Patients with lumbar fourth nerve root radiculopathy had increased physiological knee flexion immediately after foot-ground contact, possibly owing to a slight decrease in the muscle strength of the quadriceps femoris muscle. Patients with osteoarthritis of the hip had decreased range of motion of the hip joint probably due to anatomically limited mobility as well as gait strategy to avoid pain resulting from increased internal pressure on the hip joint during its extension. Our facile and noninvasive method can be useful for the differential diagnosis of lumbar spinal canal stenosis from osteoarthritis of the hip.

  6. Reorganization in the ipsilateral motor cortex of patients with lower limb amputation.

    PubMed

    Schwenkreis, Peter; Pleger, Burkhard; Cornelius, Beate; Weyen, Ute; Dertwinkel, Roman; Zenz, Michael; Malin, Jean Pierre; Tegenthoff, Martin

    2003-10-09

    The aim of the present study was to assess reorganization in the motor cortex of patients with lower limb amputation. We studied seven patients with traumatic lower limb amputation, and six healthy controls, using transcranial magnetic stimulation mapping, with recordings from the quadriceps femoris muscle on both sides. Motor threshold, sum of amplitudes, area and the amplitude-weighted centre of gravity (COG) of the motor output map were assessed. We found a significant lateral displacement of the COG on the hemisphere contralateral to the healthy leg, whereas other parameters did not differ significantly between sides. This finding might be indicative of cortical reorganization in the hemisphere ipsilateral to the amputation. It is discussed with respect to an altered peripheral input to this hemisphere, and to transcallosal interactions from the deafferented hemisphere.

  7. [Anatomy and biomechanics of the patellofemoral joint: physiological conditions and changes after total knee arthroplasty].

    PubMed

    Steinbrück, A; Milz, S; Woiczinski, M; Schröder, C; Utzschneider, S; Jansson, V; Fottner, A

    2011-10-01

    The patellofemoral joint constitutes a complex anatomical and functional entity. The tensile force of the quadriceps femoris muscle is transmitted through the patella and patellar ligament onto the tibial tuberosity. This particular three-dimensional arrangement increases the torsional moment acting on the knee joint. Dynamic alignment of the patella is determined by trochlear geometry and is supported by active muscular and passive connective tissue stabilizers. In addition to the retinaculum of the patella, the medial patellofemoral ligament is attracting increasing clinical attention. Multidirectional motion of the patella is closely connected to retropatellar pressure distribution which can be modulated by moving the patellar ligament insertion. Implantation of a knee endoprosthesis changes the joint surface geometry and consequently patella kinematics and retropatellar pressure distribution. Finite element analysis provides the possibility to assess retropatellar pressure distribution before and after implantation of prostheses.

  8. [Morphohistochemical study of skeletal muscles in rats after experimental flight on "Kosmos-1887"].

    PubMed

    Il'ina-Kakueva, E I

    1990-01-01

    Morphometric and histochemical methods were used to examine the soleus, gastrocnemius (medial portion), quadriceps femoris (central portion) and biceps brachii muscles of Wistar SPF rats two days after the 13-day flight on Cosmos-1887. It was found that significant atrophy developed only in the soleus muscle. The space flight did not change the percentage content of slow (type I) and fast (type II) fibers in fast twitch muscles. During two days at 1 g the slow soleus muscle developed substantial circulation disorders, which led to interstitial edema and necrotic changes. The gastrocnemius muscle showed small foci containing necrotic myofibers. Two days after recovery no glycogen aggregates were seen in myofibers, which were previously observed in other rats examined 4--8 hours after flight. An initial stage of muscle readaptation to 1 g occurred, when NAD.H2-dehydrogenase activity was decreased.

  9. Protein synthesis assessed by ribosome analysis in human papillary muscle in relation to oxidative capacity: a comparison with skeletal muscle.

    PubMed

    Wernerman, J; Sylvén, C; von der Decken, A; Jansson, E; Böök, K; Vinnars, E

    1988-08-01

    Protein synthesis as assessed by the concentration and size distribution of ribosomes was determined together with citrate synthase activity in papillary muscles obtained at open heart surgery from patients with mitral valve disease. The results were compared with corresponding data from the quadriceps femoris muscle of patients undergoing cholecystectomy. Citrate synthase activity was six times higher in papillary muscle than in skeletal muscle. The total ribosome concentration per mg DNA was similar in the two types of muscle. Compared with skeletal muscle, in papillary muscle polyribosomes constituted a higher proportion of the ribosomes (p less than 0.001), and there was a tendency towards larger polyribosome aggregates. It is proposed that the high concentration of polyribosomes in papillary muscle is related to the high oxidative capacity of that tissue.

  10. Muscle force estimation with surface EMG during dynamic muscle contractions: a wavelet and ANN based approach.

    PubMed

    Bai, Fengjun; Chew, Chee-Meng

    2013-01-01

    Human muscle force estimation is important in biomechanics studies, sports and assistive devices fields. Therefore, it is essential to develop an efficient algorithm to estimate force exerted by muscles. The purpose of this study is to predict force/torque exerted by muscles under dynamic muscle contractions based on continuous wavelet transform (CWT) and artificial neural networks (ANN) approaches. Mean frequency (MF) of the surface electromyography (EMG) signals power spectrum was calculated from CWT. ANN models were trained to derive the MF-force relationships from the subset of EMG signals and the measured forces. Then we use the networks to predict the individual muscle forces for different muscle groups. Fourteen healthy subjects (10 males and 4 females) were voluntarily recruited in this study. EMG signals were collected from the biceps brachii, triceps, hamstring and quadriceps femoris muscles to evaluate the proposed method. Root mean square errors (RMSE) and correlation coefficients between the predicted forces and measured actual forces were calculated.

  11. Ranked Levels of Influence Model: Selecting Influence Techniques to Minimize IT Resistance

    PubMed Central

    Bartos, Christa E.; Butler, Brian S.; Crowley, Rebecca S.

    2010-01-01

    Implementation of electronic health records (EHR), particularly computerized physician/provider order entry systems (CPOE), is often met with resistance. Influence presented at the right time, in the right manner, may minimize resistance or at least limit the risk of complete system failure. Combining established theories on power, influence tactics, and resistance, we developed the Ranked Levels of Influence model. Applying it to documented examples of EHR/CPOE failures at Cedars-Sinai and Kaiser Permanente in Hawaii, we evaluated the influence applied, the resistance encountered, and the resulting risk to the system implementation. Using the Ranked Levels of Influence model as a guideline, we demonstrate that these system failures were associated with the use of hard influence tactics that resulted in higher levels of resistance. We suggest that when influence tactics remain at the soft tactics level, the level of resistance stabilizes or de-escalates and the system can be saved. PMID:20176135

  12. Blood flow-restricted strength training displays high functional and biological efficacy in women: a within-subject comparison with high-load strength training.

    PubMed

    Ellefsen, Stian; Hammarström, Daniel; Strand, Tor A; Zacharoff, Erika; Whist, Jon E; Rauk, Irene; Nygaard, Håvard; Vegge, Geir; Hanestadhaugen, Marita; Wernbom, Mathias; Cumming, Kristoffer T; Rønning, Roar; Raastad, Truls; Rønnestad, Bent R

    2015-10-01

    Limited data exist on the efficacy of low-load blood flow-restricted strength training (BFR), as compared directly to heavy-load strength training (HST). Here, we show that 12 wk of twice-a-week unilateral BFR [30% of one repetition maximum (1RM) to exhaustion] and HST (6-10RM) of knee extensors provide similar increases in 1RM knee extension and cross-sectional area of distal parts of musculus quadriceps femoris in nine untrained women (age 22 ± 1 yr). The two protocols resulted in similar acute increases in serum levels of human growth hormone. On the cellular level, 12 wk of BFR and HST resulted in similar shifts in muscle fiber composition in musculus vastus lateralis, evident as increased MyHC2A proportions and decreased MyHC2X proportions. They also resulted in similar changes of the expression of 29 genes involved in skeletal muscle function, measured both in a rested state following 12 wk of training and subsequent to singular training sessions. Training had no effect on myonuclei proportions. Of particular interest, 1) gross adaptations to BFR and HST were greater in individuals with higher proportions of type 2 fibers, 2) both BFR and HST resulted in approximately four-fold increases in the expression of the novel exercise-responsive gene Syndecan-4, and 3) BFR provided lesser hypertrophy than HST in the proximal half of musculus quadriceps femoris and also in CSApeak, potentially being a consequence of pressure from the tourniquet utilized to achieve blood flow restriction. In conclusion, BFR and HST of knee extensors resulted in similar adaptations in functional, physiological, and cell biological parameters in untrained women.

  13. Blood flow-restricted strength training displays high functional and biological efficacy in women: a within-subject comparison with high-load strength training

    PubMed Central

    Hammarström, Daniel; Strand, Tor A.; Zacharoff, Erika; Whist, Jon E.; Rauk, Irene; Nygaard, Håvard; Vegge, Geir; Hanestadhaugen, Marita; Wernbom, Mathias; Cumming, Kristoffer T.; Rønning, Roar; Raastad, Truls; Rønnestad, Bent R.

    2015-01-01

    Limited data exist on the efficacy of low-load blood flow-restricted strength training (BFR), as compared directly to heavy-load strength training (HST). Here, we show that 12 wk of twice-a-week unilateral BFR [30% of one repetition maximum (1RM) to exhaustion] and HST (6-10RM) of knee extensors provide similar increases in 1RM knee extension and cross-sectional area of distal parts of musculus quadriceps femoris in nine untrained women (age 22 ± 1 yr). The two protocols resulted in similar acute increases in serum levels of human growth hormone. On the cellular level, 12 wk of BFR and HST resulted in similar shifts in muscle fiber composition in musculus vastus lateralis, evident as increased MyHC2A proportions and decreased MyHC2X proportions. They also resulted in similar changes of the expression of 29 genes involved in skeletal muscle function, measured both in a rested state following 12 wk of training and subsequent to singular training sessions. Training had no effect on myonuclei proportions. Of particular interest, 1) gross adaptations to BFR and HST were greater in individuals with higher proportions of type 2 fibers, 2) both BFR and HST resulted in approximately four-fold increases in the expression of the novel exercise-responsive gene Syndecan-4, and 3) BFR provided lesser hypertrophy than HST in the proximal half of musculus quadriceps femoris and also in CSApeak, potentially being a consequence of pressure from the tourniquet utilized to achieve blood flow restriction. In conclusion, BFR and HST of knee extensors resulted in similar adaptations in functional, physiological, and cell biological parameters in untrained women. PMID:26202071

  14. Hypophosphatemia and phosphorus depletion in respiratory and peripheral muscles of patients with respiratory failure due to COPD.

    PubMed

    Fiaccadori, E; Coffrini, E; Fracchia, C; Rampulla, C; Montagna, T; Borghetti, A

    1994-05-01

    In 22 patients (19 men, 3 women; mean [+/- SD] age, 63 +/- 6 years) with chronic obstructive pulmonary disease (COPD), phosphorus content was measured by spectrophotometric methods on muscle fragments of both peripheral (quadriceps femoris needle biopsy in 22 patients) and respiratory muscles (external intercostal muscle surgical biopsy in 14 patients). Thirty age- and sex-matched subjects were used as controls (19 for quadriceps femoris muscle biopsy and 11 for intercostal muscle biopsy). Serum phosphorus levels, as well as the main determinants of overall phosphorus metabolism (dietary intake of phosphorus and renal phosphate handling), were also obtained in all patients and control subjects. Muscle phosphorus content of both respiratory and peripheral muscles was significantly reduced in the COPD patient group, no matter what reference index was used (fat-free dry muscle weight or muscle fragment DNA content); muscle phosphorus depletion was present in about 50 percent of patients with COPD. In the same patient group, a significant relationship between muscle and serum phosphorus levels was demonstrable in the case of peripheral muscles only. No relationship was found between phosphorus content of both types of skeletal muscles and dietary phosphorus intake levels or with nutritional status, even though patients with COPD had significantly reduced anthropometric, biochemical, and immunologic indices as compared with controls. Renal phosphorus handling indices of the COPD patient group were compatible with a condition of inadequacy of the renal compensatory mechanism to hypophosphatemia and phosphorus depletion (low percent tubular reabsorption of phosphorus, low renal threshold concentration values). Our study suggests that phosphorus depletion occurs frequently in COPD, but in this clinical condition serum phosphorus levels are not representative of cellular phosphorus levels. Phosphorus depletion, which is equally severe in respiratory and peripheral muscles

  15. Low ponderal index is associated with decreased muscle strength and fatigue resistance in college-aged women

    PubMed Central

    Brutsaert, Tom D.; Tamvada, Kelli H.; Kiyamu, Melisa; White, Daniel D.; Gage, Timothy B

    2011-01-01

    Poor fetal growth is associated with decrements in muscle strength likely due to changes during myogenesis. We investigated the association of poor fetal growth with muscle strength, fatigue resistance, and the response to training in the isolated quadriceps femoris. Females (20.6 yrs) born to term but below the 10th percentile of ponderal index (PI)-for-gestational-age (LOWPI, n=14) were compared to controls (HIGHPI, n=14), before and after an 8-week training. Muscle strength was assessed as grip-strength and as the maximal isometric voluntary contraction (MVC) of the quadriceps femoris. Muscle fatigue was assessed during knee extension eercise. Body composition and the maximal oxygen consumption (VO2max) were also measured. Controlling for fat free mass (FFM), LOWPI versus HIGHPI women had ~11% lower grip-strength (P=0.023), 9–24% lower MVC values (P=0.042 pre-trained; P=0.020 post-trained), a higher rate of fatigue (pre- and post-training), and a diminished training response (P=0.016). Statistical control for FFM increased rather than decreased strength differences between PI groups. The PI was not associated with VO2max or measures of body composition. Strength and fatigue decrements strongly suggest that poor fetal growth affects the pathway of muscle force generation. This could be due to neuromotor and/or muscle morphologic changes during development e.g., fiber number, fiber type, etc. Muscle from LOWPI women may also be less responsive to training. Indirectly, results also implicate muscle as a potential mediator between poor fetal growth and adult chronic disease, given muscle’s direct role in determining insulin resistance, type II diabetes, physical activity, and so forth. PMID:21641734

  16. Reduction of O2 slow component by priming exercise: novel mechanistic insights from time-resolved near-infrared spectroscopy

    PubMed Central

    Fukuoka, Yoshiyuki; Poole, David C; Barstow, Thomas J; Kondo, Narihiko; Nishiwaki, Masato; Okushima, Dai; Koga, Shunsaku

    2015-01-01

    Novel time-resolved near-infrared spectroscopy (TR-NIRS), with adipose tissue thickness correction, was used to test the hypotheses that heavy priming exercise reduces the V̇O2 slow component (V̇O2SC) (1) by elevating microvascular [Hb] volume at multiple sites within the quadriceps femoris (2) rather than reducing the heterogeneity of muscle deoxygenation kinetics. Twelve subjects completed two 6-min bouts of heavy work rate exercise, separated by 6 min of unloaded cycling. Priming exercise induced faster overall V̇O2 kinetics consequent to a substantial reduction in the V̇O2SC (0.27 ± 0.12 vs. 0.11 ± 0.09 L·min−1, P < 0.05) with an unchanged primary V̇O2 time constant. An increased baseline for the primed bout [total (Hb + Mb)] (197.5 ± 21.6 vs. 210.7 ± 22.5 μmol L−1, P < 0.01), reflecting increased microvascular [Hb] volume, correlated significantly with the V̇O2SC reduction. At multiple sites within the quadriceps femoris, priming exercise reduced the baseline and slowed the increase in [deoxy (Hb + Mb)]. Changes in the intersite coefficient of variation in the time delay and time constant of [deoxy (Hb + Mb)] during the second bout were not correlated with the V̇O2SC reduction. These results support a mechanistic link between priming exercise-induced increase in muscle [Hb] volume and the reduced V̇O2SC that serves to speed overall V̇O2 kinetics. However, reduction in the heterogeneity of muscle deoxygenation kinetics does not appear to be an obligatory feature of the priming response. PMID:26109190

  17. Funktionelle Elektrostimulation Paraplegischer Patienten

    PubMed Central

    2014-01-01

    Functional Electrical Stimulation on Paraplegic Patients. We report on clinical and physiological effects of 8 months Functional Electrical Stimulation (FES) of quadriceps femoris muscle on 16 paraplegic patients. Each patient had muscle biopsies, CT-muscle diameter measurements, knee extension strength testing carried out before and after 8 months FES training. Skin perfusion was documented through infrared telethermography and xenon clearance, muscle perfusion was recorded through thallium scintigraphy. After 8 months FES training baseline skin perfusion showed 86 % increase, muscle perfusion was augmented by 87 %. Muscle fiber diameters showed an average increase of 59 % after 8 months FES training. Muscles in patients with spastic paresis as well as in patients with denervation showed an increase in aerob and anaerob muscle enzymes up to the normal range. Even without axonal neurotropic substances FES was able to demonstrate fiberhypertrophy, enzyme adaptation and intracellular structural benefits in denervated muscles. The increment in muscle area as visible on CT-scans of quadriceps femoris was 30 % in spastic paraplegia and 10 % in denervated patients respectively. FES induced changes were less in areas not directly underneath the surface electrodes. We strongly recommend the use of Kern’s current for FES in denervated muscles to induce tetanic muscle contractions as we formed a very critical opinion of conventional exponential current. In patients with conus-cauda-lesions FES must be integrated into modern rehabilitation to prevent extreme muscle degeneration and decubital ulcers. Using FES we are able to improve metabolism and induce positive trophic changes in our patients lower extremities. In spastic paraplegics the functions „rising and walking“ achieved through FES are much better training than FES ergometers. Larger muscle masses are activated and an increased heart rate is measured, therefore the impact on cardiovascular fitness and metabolism

  18. INFLUENCE OF MACROMOLECULES ON CHEMICAL TRANSPORT

    EPA Science Inventory

    Macromolecules in the pore fluid influence the mobility of hydrophobic compounds through soils. his study evaluated the significance of macromolecules in facilitating chemical transport under laboratory conditions. Partition coefficients between 14C-labeled hexachlorobenzene and ...

  19. Latina mothers' influences on child appetite regulation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Parents influence child weight through interactions that shape the development of child eating behaviors. In this study we examined the association between maternal autonomy promoting serving practices and child appetite regulation. We predicted that maternal autonomy promoting serving practices wou...

  20. Cultural and Technological Influences: An Introduction.

    ERIC Educational Resources Information Center

    Shank, Russell

    1992-01-01

    Discusses cultural and technological influences in the management of human resources in the research library and their impact on individual rights and responsibilities, division of labor, supervision, educational requirements, and job stress. (23 references) (EA)

  1. Parental Influence on Young People's Career Development.

    ERIC Educational Resources Information Center

    Otto, Luther B.; Call, Vaughn R. A.

    1985-01-01

    Describes theory and research on parental influence on young people's career development and highlights an important implication of this relationship for career counseling. The authors discuss a seminar that helps parents help their children choose careers. (CT)

  2. Diseases and Conditions That Influence Fertility

    MedlinePlus

    ... and Conditions That Influence Fertility Skip sharing on social media links Share this: Page Content Many different health issues can affect a woman's ability to get pregnant. Some of the more common ...

  3. Hotel Housekeeping Work Influences on Hypertension Management

    PubMed Central

    Sanon, Marie-Anne

    2013-01-01

    Background Characteristics of hotel housekeeping work increase the risk for hypertension development. Little is known about the influences of such work on hypertension management. Methods For this qualitative study, 27 Haitian immigrant hotel housekeepers from Miami-Dade County, FL were interviewed. Interview transcripts were analyzed with the assistance of the Atlas. ti software for code and theme identification. Results Influences of hotel housekeeping work on hypertension management arose both at the individual and system levels. Factors at the individual level included co-worker dynamics and maintenance of transmigrant life. Factors at the system level included supervisory support, workload, work pace, and work hiring practices. No positive influences were reported for workload and hiring practices. Conclusions Workplace interventions may be beneficial for effective hypertension management among hotel housekeepers. These work influences must be considered when determining effective methods for hypertension management among hotel housekeepers. PMID:23775918

  4. [Distant mental influence on living organisms].

    PubMed

    Bonilla, Ernesto

    2013-12-01

    This article reviews studies of distant mental influence on living organisms, including mental suggestions of sleeping and awakening, mental influence at long distances, mental interactions with remote biological systems, mental effects on physiological activity and the sense of being stared at. Significant effects of distant mental influence have been shown in several randomized controlled trials in humans, animals, plants, bacteria and cells in the laboratory. Although distant mental influence on living organisms appears to contradict our ordinary sense of reality and the laws defined by conventional science, several hypotheses have been proposed to explain the observed effects; they include skeptical, signal transfer, field, multidimensional space/time and quantum mechanics hypotheses. In conclusion, as the progress of physics continues to expand our comprehension of reality, a rational explanation for distant mind-matter interaction will emerge and, as history has shown repeatedly, the supernatural events will evolve into paranormal and then, into normal ones, as the scientific frontiers expand.

  5. Follow your heart: Emotion adaptively influences perception

    PubMed Central

    Stefanucci, Jeanine K.; Gagnon, Kyle T.; Lessard, David A.

    2011-01-01

    The current review introduces a new program of research that suggests the perception of spatial layout is influenced by emotions. Though perceptual systems are often described as closed and insulated, this review presents research suggesting that a variety of induced emotions (e.g., fear, disgust, sadness) can produce changes in vision and audition. Thus, the perceptual system may be highly interconnected, allowing emotional information to influence perceptions that, in turn, influence cognition. The body of work presented here also suggests that emotion-based changes in perception help us solve particular adaptive problems because emotion does not change all perceptions of the world. Taking the adaptive significance of emotion into account allows us to make predictions about when and how emotion influences perception. PMID:21731579

  6. Factors that influence women's dispositions toward science

    NASA Astrophysics Data System (ADS)

    Atria, Catherine Graczyk

    Females have been underrepresented in the study of science and science careers for decades although advancements have been made in closing this gender gap, the gap persists particularly in the physical sciences. Variables which influence a woman's desire to pursue and maintain a science course of study and career must be discovered. The United States lags behind other industrialized countries in the fields of science, math, and engineering. Females comprise an estimated half of the population; their potential contributions cannot be ignored or overlooked. This retrospective research study explores the personal experiences of ten women enrolled in science majors, with science related career plans. The goal of this study is to describe the factors that influence the participants' interest in science. The findings, the effect of science coursework, science teachers' personality and manner, other influential educational personnel, role models and mentors, external influences exclusive of school, parental influence, locus of control and positive attitudes toward science confirm what other researchers have found.

  7. Influence network in the Chinese stock market

    NASA Astrophysics Data System (ADS)

    Gao, Ya-Chun; Zeng, Yong; Cai, Shi-Min

    2015-03-01

    In a stock market, the price fluctuations are interactive, that is, one listed company can influence others. In this paper, we seek to study the influence relationships among listed companies by constructing a directed network on the basis of the Chinese stock market. This influence network shows distinct topological properties. In particular, a few large companies that can lead the tendency of the stock market are recognized. Furthermore, by analyzing the subnetworks of listed companies distributed in several significant economic sectors, it is found that the influence relationships are totally different from one economic sector to another, of which three types of connectivity as well as hub-like listed companies are identified. In addition, the rankings of listed companies obtained from the centrality metrics of the influence network are compared with those according to the assets, which gives inspiration to uncover and understand the importance of listed companies on the stock market. These empirical results are meaningful in providing these topological properties of the Chinese stock market and economic sectors as well as revealing the interactive influence relationships among listed companies.

  8. Neural mechanisms of social influence in adolescence

    PubMed Central

    Welborn, B. Locke; Lieberman, Matthew D.; Goldenberg, Diane; Fuligni, Andrew J.; Galván, Adriana

    2016-01-01

    During the transformative period of adolescence, social influence plays a prominent role in shaping young people’s emerging social identities, and can impact their propensity to engage in prosocial or risky behaviors. In this study, we examine the neural correlates of social influence from both parents and peers, two important sources of influence. Nineteen adolescents (age 16–18 years) completed a social influence task during a functional magnetic resonance imaging (fMRI) scan. Social influence from both sources evoked activity in brain regions implicated in mentalizing (medial prefrontal cortex, left temporoparietal junction, right temporoparietal junction), reward (ventromedial prefrontal cortex), and self-control (right ventrolateral prefrontal cortex). These results suggest that mental state reasoning, social reward and self-control processes may help adolescents to evaluate others’ perspectives and overcome the prepotent force of their own antecedent attitudes to shift their attitudes toward those of others. Findings suggest common neural networks involved in social influence from both parents and peers. PMID:26203050

  9. Neuromuscular Responses to Short-Term Resistance Training With Traditional and Daily Undulating Periodization in Adolescent Elite Judoka.

    PubMed

    Ullrich, Boris; Pelzer, Thiemo; Oliveira, Sergio; Pfeiffer, Mark

    2016-08-01

    Ullrich, B, Pelzer, T, Oliveira, S, and Pfeiffer, M. Neuromuscular responses to short-term resistance training with traditional and daily undulating periodization in adolescent elite judoka. J Strength Cond Res 30(8): 2083-2099, 2016-The influence of different periodization models on neuromuscular outcomes after short-term strength training periods has not been examined in adolescent athletes. Eleven elite judoka (age: 14.8 ± 0.6 years, height: 163.2 ± 7.5 cm, body mass: 57.3 ± 11.1 kg, 5 boys/6 girls, and strength training experience: 2.7 ± 1.1 years) performed two 4-week strength training mesocycles (each with 12 sessions) with either traditional (TP) or daily undulating (DUP) periodization. Both mesocycles were separated by a 7-week washout period and added to the regular judo training. Strength training was performed as lifting and lowering of weights using squats, knee flexion curl, clean & jerk, snatch, bench press, barbell bench pull, and lat pull-down. The mesocycles were equated for the number of repetitions and different intensity zones (50-90% of 1 repetition maximum [1RM]), addressing the optimization of strength, power, or velocity. Laboratory and 1RM testing was carried out 2 times during the baseline (T1 and T2), after the TP mesocycle (T3), after the washout period (T4), and after the DUP mesocycle (T5). Isometric knee extensor and knee flexor maximum voluntary contractive capacity (MVC), electromyographic-estimated neural drive of the quadriceps femoris, vastus lateralis (VL) muscle architecture, and 1RMs of all training exercises were measured. ANOVA revealed moderate (5.5-13.5%) but significant (p ≤ 0.05) temporal gains in knee extensor MVC, 1RMs, and VL architecture during both the mesocycles. Wilcoxon tests detected no significant differences for the percentage changes of any outcome between the mesocycles. For adolescent judoka, TP and DUP were equally adept in improving neuromuscular outcomes during short-term training periods.

  10. The effects of progressive functional training on lower limb muscle architecture and motor function in children with spastic cerebral palsy

    PubMed Central

    Lee, MiHye; Ko, YoungJun; Shin, Mary Myong Sook; Lee, Wanhee

    2015-01-01

    [Purpose] To investigate the effects of progressive functional training on lower limb muscle architecture and motor function of children with spastic cerebral palsy (CP). [Subjects] The subjects of this study were 26 children with spastic CP. [Methods] Thirteen subjects in the experimental group performed general neurodevelopmental treatment (NDT) and additional progressive functional trainings and 13 subjects in the control group performed only general NDT 3 times a week for 6 weeks. Ultrasonography, gross motor function measurement (GMFM) and the mobility questionnaire (MobQue) were evaluated. [Results] After the intervention, the muscle thickness of the quadriceps femoris (QF), cross-sectional area of the rectus femoris (RF), pennation angle of the gastrocnemius (GCM) and the MobQue score of the experimental group were significantly greater than those of the control group. The muscle thickness of QF correlated with the cross-sectional area (CSA) of RF and the pennation angle of GCM, and GMFM score correlated with the pennation angle of GCM. [Conclusion] Progressive functional training can increase muscle thickness, CSA, and the pennation angle of the lower limb muscles, and improve the mobility of spastic CP children making it useful as a practical adjunct to rehabilitation therapy. PMID:26157267

  11. Effect of vacuum ageing on quality changes of lamb steaks from early fattening lambs during aerobic display.

    PubMed

    Callejas-Cárdenas, Aída R; Caro, Irma; Blanco, Carolina; Villalobos-Delgado, Luz H; Prieto, Nuria; Bodas, Raúl; Giráldez, Francisco J; Mateo, Javier

    2014-12-01

    The effects of vacuum ageing on the quality changes of lamb steaks during retail display were assessed. Biceps femoris and Quadriceps femoris muscles from thirty early fattening lambs fed barley straw and concentrate or alfalfa and concentrate were used. Half of the muscles were vacuum aged for three weeks (VA), and the other half were not aged (control). Control and VA muscles were sliced and aerobically displayed. Weight loss, pH, aldehyde contents, instrumental color characteristics and color acceptance were measured at display days 1, 3, 7 and 14. At day 1 redness was higher in VA lamb. However, redness of VA lamb decreases more rapidly during further storage. Redness and color acceptance decreased in VA lamb from day 3, whereas in not-aged lamb the decrease was observed from day 7 onwards. From days 7 to 14 a drop of color acceptance accompanied by an increase in pH and a decrease in lightness was observed in control and VA lamb.

  12. Comparison of hot versus cold boning of beef carcasses on bacterial growth and the risk of blown pack spoilage.

    PubMed

    Reid, Rachael; Fanning, Séamus; Whyte, Paul; Kerry, Joe; Bolton, Declan

    2017-03-01

    Primals were prepared from beef Longissimus thoracis et lumborum (LTL), psoas major (PM), quadriceps femoris (QF) and semitendinosus (S) muscles from cold and hot boned carcasses, vacuum-packaged and stored for 42 or 100days at 2°C and 7°C. Storage temperature, carcass or primal surface temperature, pH and aw were monitored. Samples were taken periodically and tested for total viable count mesophilic (TVCm), TVC psychrophilic (TVCp), total Enterobacteriaceae count (TEC), presumptive Pseudomonas spp., lactic acid bacteria (LAB), Clostridium spp. and Brochothrix thermosphacta. A fifth muscle, biceps femoris (BF), was used to examine the impact of hot boning on blown pack spoilage (BPS). Primal counts increased to 6-7log10cfucm(-2) after 6weeks. Significantly (P<0.05) higher TEC, Pseudomonas spp. and Br. thermosphacta counts were observed on cold versus hot boned primals. In contrast, significantly (P<0.05) higher TVC, LAB and Clostridium spp. concentrations were obtained on hot boned beef. Moreover, BPS pack distension/bursting occurred considerably sooner in hot boned product.