Task driven optimal leg trajectories in insect-scale legged microrobots

NASA Astrophysics Data System (ADS)

Doshi, Neel; Goldberg, Benjamin; Jayaram, Kaushik; Wood, Robert

Origami inspired layered manufacturing techniques and 3D-printing have enabled the development of highly articulated legged robots at the insect-scale, including the 1.43g Harvard Ambulatory MicroRobot (HAMR). Research on these platforms has expanded its focus from manufacturing aspects to include design optimization and control for application-driven tasks. Consequently, the choice of gait selection, body morphology, leg trajectory, foot design, etc. have become areas of active research. HAMR has two controlled degrees-of-freedom per leg, making it an ideal candidate for exploring leg trajectory. We will discuss our work towards optimizing HAMR's leg trajectories for two different tasks: climbing using electroadhesives and level ground running (5-10 BL/s). These tasks demonstrate the ability of single platform to adapt to vastly different locomotive scenarios: quasi-static climbing with controlled ground contact, and dynamic running with un-controlled ground contact. We will utilize trajectory optimization methods informed by existing models and experimental studies to determine leg trajectories for each task. We also plan to discuss how task specifications and choice of objective function have contributed to the shape of these optimal leg trajectories.

Influence of unstable footwear on lower leg muscle activity, volume change and subjective discomfort during prolonged standing.

PubMed

Karimi, Zanyar; Allahyari, Teimour; Azghani, Mahmood Reza; Khalkhali, Hamidreza

2016-03-01

The present study was an attempt to investigate the effect of unstable footwear on lower leg muscle activity, volume change and subjective discomfort during prolonged standing. Ten healthy subjects were recruited to stand for 2 h in three footwear conditions: barefoot, flat-bottomed shoe and unstable shoe. During standing, lower leg discomfort and EMG activity of medial gastrocnemius (MG) and tibialis anterior (TA) muscles were continuously monitored. Changes in lower leg volume over standing time also were measured. Lower leg discomfort rating reduced significantly while subjects standing on unstable shoe compared to the flat-bottomed shoe and barefoot condition. For lower leg volume, less changes also were observed with unstable shoe. The activity level and variation of right MG muscle was greater with unstable shoe compared to the other footwear conditions; however regarding the left MG muscle, significant difference was found between unstable shoe and flat-bottomed shoe only for activity level. Furthermore no significant differences were observed for the activity level and variation of TA muscles (right/left) among all footwear conditions. The findings suggested that prolonged standing with unstable footwear produces changes in lower leg muscles activity and leads to less volume changes. Perceived discomfort also was lower for this type of footwear and this might mean that unstable footwear can be used as ergonomic solution for employees whose work requires prolonged standing. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Applying a pelvic corrective force induces forced use of the paretic leg and improves paretic leg EMG activities of individuals post-stroke during treadmill walking.

PubMed

Hsu, Chao-Jung; Kim, Janis; Tang, Rongnian; Roth, Elliot J; Rymer, William Z; Wu, Ming

2017-10-01

To determine whether applying a mediolateral corrective force to the pelvis during treadmill walking would enhance muscle activity of the paretic leg and improve gait symmetry in individuals with post-stroke hemiparesis. Fifteen subjects with post-stroke hemiparesis participated in this study. A customized cable-driven robotic system based over a treadmill generated a mediolateral corrective force to the pelvis toward the paretic side during early stance phase. Three different amounts of corrective force were applied. Electromyographic (EMG) activity of the paretic leg, spatiotemporal gait parameters and pelvis lateral displacement were collected. Significant increases in integrated EMG of hip abductor, medial hamstrings, soleus, rectus femoris, vastus medialis and tibialis anterior were observed when pelvic corrective force was applied, with pelvic corrective force at 9% of body weight inducing greater muscle activity than 3% or 6% of body weight. Pelvis lateral displacement was more symmetric with pelvic corrective force at 9% of body weight. Applying a mediolateral pelvic corrective force toward the paretic side may enhance muscle activity of the paretic leg and improve pelvis displacement symmetry in individuals post-stroke. Forceful weight shift to the paretic side could potentially force additional use of the paretic leg and improve the walking pattern. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Movement of the sacroiliac joint during the Active Straight Leg Raise test in patients with long-lasting severe sacroiliac joint pain.

PubMed

Kibsgård, Thomas J; Röhrl, Stephan M; Røise, Olav; Sturesson, Bengt; Stuge, Britt

2017-08-01

The Active Straight Leg Raise is a functional test used in the assessment of pelvic girdle pain, and has shown to have good validity, reliability and responsiveness. The Active Straight Leg Raise is considered to examine the patients' ability to transfer load through the pelvis. It has been hypothesized that patients with pelvic girdle pain lack the ability to stabilize the pelvic girdle, probably due to instability or increased movement of the sacroiliac joint. This study examines the movement of the sacroiliac joints during the Active Straight Leg Raise in patients with pelvic girdle pain. Tantalum markers were inserted in the dorsal sacrum and ilium of 12 patients with long-lasting pelvic girdle pain scheduled for sacroiliac joint fusion surgery. Two to three weeks later movement of the sacroiliac joints during the Active Straight Leg Raise was measured with radiostereometric analysis. Small movements were detected. There was larger movement of the sacroiliac joint of the rested leg's sacroiliac joint compared to the lifted leg's side. A mean backward rotation of 0.8° and inward tilt of 0.3° were seen in the rested leg's sacroiliac joint. The movements of the sacroiliac joints during the Active Straight Leg Raise are small. There was a small backward rotation of the innominate bone relative to sacrum on the rested leg's side. Our findings contradict an earlier understanding that a forward rotation of the lifted leg's innominate occur while performing the Active Straight Leg Raise. Copyright © 2017. Published by Elsevier Ltd.

Venous leg ulcers

PubMed Central

2011-01-01

Introduction Leg ulcers usually occur secondary to venous reflux or obstruction, but 20% of people with leg ulcers have arterial disease, with or without venous disorders. Between 1.5 and 3.0/1000 people have active leg ulcers. Prevalence increases with age to about 20/1000 in people aged over 80 years. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of standard treatments, adjuvant treatments, and organisational interventions for venous leg ulcers? What are the effects of advice about self-help interventions in people receiving usual care for venous leg ulcers? What are the effects of interventions to prevent recurrence of venous leg ulcers? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2011 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 101 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: compression bandages and stockings, cultured allogenic (single or bilayer) skin replacement, debriding agents, dressings (cellulose, collagen, film, foam, hyaluronic acid-derived, semi-occlusive alginate), hydrocolloid (occlusive) dressings in the presence of compression, intermittent pneumatic compression, intravenous prostaglandin E1, larval therapy, laser treatment (low-level), leg ulcer clinics, multilayer elastic system, multilayer elastomeric (or non-elastomeric) high-compression regimens or bandages, oral treatments (aspirin, flavonoids

Early (N170) activation of face-specific cortex by face-like objects

PubMed Central

Hadjikhani, Nouchine; Kveraga, Kestutis; Naik, Paulami; Ahlfors, Seppo P.

2009-01-01

The tendency to perceive faces in random patterns exhibiting configural properties of faces is an example of pareidolia. Perception of ‘real’ faces has been associated with a cortical response signal arising at about 170ms after stimulus onset; but what happens when non-face objects are perceived as faces? Using magnetoencephalography (MEG), we found that objects incidentally perceived as faces evoked an early (165ms) activation in the ventral fusiform cortex, at a time and location similar to that evoked by faces, whereas common objects did not evoke such activation. An earlier peak at 130 ms was also seen for images of real faces only. Our findings suggest that face perception evoked by face-like objects is a relatively early process, and not a late re-interpretation cognitive phenomenon. PMID:19218867

Early (M170) activation of face-specific cortex by face-like objects.

PubMed

Hadjikhani, Nouchine; Kveraga, Kestutis; Naik, Paulami; Ahlfors, Seppo P

2009-03-04

The tendency to perceive faces in random patterns exhibiting configural properties of faces is an example of pareidolia. Perception of 'real' faces has been associated with a cortical response signal arising at approximately 170 ms after stimulus onset, but what happens when nonface objects are perceived as faces? Using magnetoencephalography, we found that objects incidentally perceived as faces evoked an early (165 ms) activation in the ventral fusiform cortex, at a time and location similar to that evoked by faces, whereas common objects did not evoke such activation. An earlier peak at 130 ms was also seen for images of real faces only. Our findings suggest that face perception evoked by face-like objects is a relatively early process, and not a late reinterpretation cognitive phenomenon.

Activity in descending dopaminergic neurons represents but is not required for leg movements in the fruit fly Drosophila

PubMed Central

Tschida, Katherine; Bhandawat, Vikas

2015-01-01

Modulatory descending neurons (DNs) that link the brain to body motor circuits, including dopaminergic DNs (DA-DNs), are thought to contribute to the flexible control of behavior. Dopamine elicits locomotor-like outputs and influences neuronal excitability in isolated body motor circuits over tens of seconds to minutes, but it remains unknown how and over what time scale DA-DN activity relates to movement in behaving animals. To address this question, we identified DA-DNs in the Drosophila brain and developed an electrophysiological preparation to record and manipulate the activity of these cells during behavior. We find that DA-DN spike rates are rapidly modulated during a subset of leg movements and scale with the total speed of ongoing leg movements, whether occurring spontaneously or in response to stimuli. However, activating DA-DNs does not elicit leg movements in intact flies, nor do acute bidirectional manipulations of DA-DN activity affect the probability or speed of leg movements over a time scale of seconds to minutes. Our findings indicate that in the context of intact descending control, changes in DA-DN activity are not sufficient to influence ongoing leg movements and open the door to studies investigating how these cells interact with other descending and local neuromodulatory inputs to influence body motor output. PMID:25742959

Differences in kinematics and electromyographic activity between men and women during the single-legged squat.

PubMed

Zeller, Brian L; McCrory, Jean L; Kibler, W Ben; Uhl, Timothy L

2003-01-01

Numerous factors have been identified as potentially increasing the risk of anterior cruciate ligament injury in the female athlete. However, differences between the sexes in lower extremity coordination, particularly hip control, are only minimally understood. There is no difference in kinematic or electromyographic data during the single-legged squat between men and women. Descriptive comparison study. We kinematically and electromyographically analyzed the single-legged squat in 18 intercollegiate athletes (9 male, 9 female). Subjects performed five single-legged squats on their dominant leg, lowering themselves as far as possible and then returning to a standing position without losing balance. Women demonstrated significantly more ankle dorsiflexion, ankle pronation, hip adduction, hip flexion, hip external rotation, and less trunk lateral flexion than men. These factors were associated with a decreased ability of the women to maintain a varus knee position during the squat as compared with the men. Analysis of all eight tested muscles demonstrated that women had greater muscle activation compared with men. When each muscle was analyzed separately, the rectus femoris muscle activation was found to be statistically greater in women in both the area under the linear envelope and maximal activation data. Under a physiologic load in a position commonly assumed in sports, women tend to position their entire lower extremity and activate muscles in a manner that could increase strain on the anterior cruciate ligament.

Leg Movement Activity During Sleep in Adults With Attention-Deficit/Hyperactivity Disorder.

PubMed

Garbazza, Corrado; Sauter, Cornelia; Paul, Juliane; Kollek, Jenny; Dujardin, Catharine; Hackethal, Sandra; Dorn, Hans; Peter, Anita; Hansen, Marie-Luise; Manconi, Mauro; Ferri, Raffaele; Danker-Hopfe, Heidi

2018-01-01

Objectives: To conduct a first detailed analysis of the pattern of leg movement (LM) activity during sleep in adult subjects with Attention-Deficit/Hyperactivity Disorder (ADHD) compared to healthy controls. Methods: Fifteen ADHD patients and 18 control subjects underwent an in-lab polysomnographic sleep study. The periodic character of LMs was evaluated with established markers of "periodicity," i.e., the periodicity index, intermovement intervals, and time distribution of LM during sleep, in addition to standard parameters such as the periodic leg movement during sleep index (PLMSI) and the periodic leg movement during sleep arousal index (PLMSAI). Subjective sleep and psychiatric symptoms were assessed using several, self-administered, screening questionnaires. Results: Objective sleep parameters from the baseline night did not significantly differ between ADHD and control subjects, except for a longer sleep latency (SL), a longer duration of the periodic leg movements during sleep (PLMS) in REM sleep and a higher PLMSI also in REM sleep. Data from the sleep questionnaires showed perception of poor sleep quality in ADHD patients. Conclusions: Leg movements during sleep in ADHD adults are not significantly more frequent than in healthy controls and the nocturnal motor events do not show an increased periodicity in these patients. The non-periodic character of LMs in ADHD has already been shown in children and seems to differentiate ADHD from other pathophysiological related conditions like restless legs syndrome (RLS) or periodic limb movement disorder (PLMD). The reduced subjective sleep quality reported by ADHD adults contrasted with the normal objective polysomnographic parameters, which could suggest a sleep-state misperception in these individuals or more subtle sleep abnormalities not picked up by the traditional sleep staging.

Pediatric restless legs syndrome: analysis of symptom descriptions and drawings.

PubMed

Picchietti, Daniel L; Arbuckle, Robert A; Abetz, Linda; Durmer, Jeffrey S; Ivanenko, Anna; Owens, Judith A; Croenlein, Jens; Allen, Richard P; Walters, Arthur S

2011-11-01

The specific aims of this study were to collect and analyze detailed symptom descriptions from patients with pediatric restless legs syndrome, ages 6 to 17 years, as well as assess symptom impact and the usefulness of drawings. Trained qualitative interviewers conducted face-to-face audio-recorded interviews of children and adolescents who met criteria for definite restless legs syndrome. Thirty-three patients in 3 age groups used 16 different categories of descriptors for restless legs sensations, with a mean of 3 or more categories used per patient in each age group. "Need to move/kick," "pain/hurts," "uncomfortable/cannot get comfortable," and "like bugs or ants/crawling" were the most common descriptors. Two-thirds reported daytime sensations, and nearly half had arm involvement. They described impact on sleep, cognitive function, and affect. Drawings provided useful diagnostic information. These detailed empirical data will be useful in clinical practice, as well as in the development of formal diagnostic tools and severity measures.

An anterior cruciate ligament injury does not affect the neuromuscular function of the non-injured leg except for dynamic balance and voluntary quadriceps activation.

PubMed

Zult, Tjerk; Gokeler, Alli; van Raay, Jos J A M; Brouwer, Reinoud W; Zijdewind, Inge; Hortobágyi, Tibor

2017-01-01

The function of the anterior cruciate ligament (ACL) patients' non-injured leg is relevant in light of the high incidence of secondary ACL injuries on the contralateral side. However, the non-injured leg's function has only been examined for a selected number of neuromuscular outcomes and often without appropriate control groups. We measured a broad array of neuromuscular functions between legs of ACL patients and compared outcomes to age, sex, and physical activity matched controls. Thirty-two ACL-deficient patients (208 ± 145 days post-injury) and active and less-active controls (N = 20 each) participated in the study. We measured single- and multi-joint neuromuscular function in both legs in each group and expressed the overall neuromuscular function in each leg by calculating a mean z-score across all neuromuscular measures. A group by leg MANOVA and ANOVA were performed to examine group and leg differences for the selected outcomes. After an ACL injury, duration (-4.3 h/week) and level (Tegner activity score of -3.9) of sports activity decreased and was comparable to less-active controls. ACL patients showed bilateral impairments in the star excursion balance test compared to both control groups (P ≤ 0.004) and for central activation ratio compared to active controls (P ≤ 0.002). There were between-leg differences within each group for maximal quadriceps and hamstring strength, voluntary quadriceps activation, star excursion balance test performance, and single-leg hop distance (all P < 0.05), but there were no significant differences in quadriceps force accuracy and variability, knee joint proprioception, and static balance. Overall neuromuscular function (mean z-score) did not differ between groups, but ACL patients' non-injured leg displayed better neuromuscular function than the injured leg (P < 0.05). Except for poorer dynamic balance and reduced quadriceps activation, ACL patients had no bilateral neuromuscular deficits despite

The changing face of emotion: age-related patterns of amygdala activation to salient faces.

PubMed

Todd, Rebecca M; Evans, Jennifer W; Morris, Drew; Lewis, Marc D; Taylor, Margot J

2011-01-01

The present study investigated age-related differences in the amygdala and other nodes of face-processing networks in response to facial expression and familiarity. fMRI data were analyzed from 31 children (3.5-8.5 years) and 14 young adults (18-33 years) who viewed pictures of familiar (mothers) and unfamiliar emotional faces. Results showed that amygdala activation for faces over a scrambled image baseline increased with age. Children, but not adults, showed greater amygdala activation to happy than angry faces; in addition, amygdala activation for angry faces increased with age. In keeping with growing evidence of a positivity bias in young children, our data suggest that children find happy faces to be more salient or meaningful than angry faces. Both children and adults showed preferential activation to mothers' over strangers' faces in a region of rostral anterior cingulate cortex associated with self-evaluation, suggesting that some nodes in frontal evaluative networks are active early in development. This study presents novel data on neural correlates of face processing in childhood and indicates that preferential amygdala activation for emotional expressions changes with age.

Venous leg ulcers

PubMed Central

2008-01-01

Introduction Leg ulcers usually occur secondary to venous reflux or obstruction, but 20% of people with leg ulcers have arterial disease, with or without venous disorders. Between 1.5 and 3.0/1000 people have active leg ulcers. Prevalence increases with age to about 20/1000 in people aged over 80 years. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of standard treatments, adjuvant treatments, and organisational interventions for venous leg ulcers? What are the effects of interventions to prevent recurrence of venous leg ulcers? We searched: Medline, Embase, The Cochrane Library, and other important databases up to September 2007 (BMJ Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 80 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: compression bandages and stockings, cultured allogenic (single or bilayer) skin replacement, debriding agents, dressings (cellulose, collagen, film, foam, hyaluronic acid-derived, semi-occlusive alginate), hydrocolloid (occlusive) dressings in the presence of compression, intermittent pneumatic compression, intravenous prostaglandin E1, larval therapy, laser treatment (low-level), leg ulcer clinics, multilayer elastic system, multilayer elastomeric (or non-elastomeric) high-compression regimens or bandages, oral treatments (aspirin, flavonoids, pentoxifylline, rutosides, stanozolol, sulodexide, thromboxane alpha2 antagonists, zinc), peri

Leg kinematics and muscle activity during treadmill running in the cockroach, Blaberus discoidalis: I. Slow running.

PubMed

Watson, J T; Ritzmann, R E

1998-01-01

We have combined high-speed video motion analysis of leg movements with electromyogram (EMG) recordings from leg muscles in cockroaches running on a treadmill. The mesothoracic (T2) and metathoracic (T3) legs have different kinematics. While in each leg the coxa-femur (CF) joint moves in unison with the femurtibia (FT) joint, the relative joint excursions differ between T2 and T3 legs. In T3 legs, the two joints move through approximately the same excursion. In T2 legs, the FT joint moves through a narrower range of angles than the CF joint. In spite of these differences in motion, no differences between the T2 and T3 legs were seen in timing or qualitative patterns of depressor coxa and extensor tibia activity. The average firing frequencies of slow depressor coxa (Ds) and slow extensor tibia (SETi) motor neurons are directly proportional to the average angular velocity of their joints during stance. The average Ds and SETi firing frequency appears to be modulated on a cycle-by-cycle basis to control running speed and orientation. In contrast, while the frequency variations within Ds and SETi bursts were consistent across cycles, the variations within each burst did not parallel variations in the velocity of the relevant joints.

The changing face of emotion: age-related patterns of amygdala activation to salient faces

PubMed Central

Evans, Jennifer W.; Morris, Drew; Lewis, Marc D.; Taylor, Margot J.

2011-01-01

The present study investigated age-related differences in the amygdala and other nodes of face-processing networks in response to facial expression and familiarity. fMRI data were analyzed from 31 children (3.5–8.5 years) and 14 young adults (18–33 years) who viewed pictures of familiar (mothers) and unfamiliar emotional faces. Results showed that amygdala activation for faces over a scrambled image baseline increased with age. Children, but not adults, showed greater amygdala activation to happy than angry faces; in addition, amygdala activation for angry faces increased with age. In keeping with growing evidence of a positivity bias in young children, our data suggest that children find happy faces to be more salient or meaningful than angry faces. Both children and adults showed preferential activation to mothers’ over strangers’ faces in a region of rostral anterior cingulate cortex associated with self-evaluation, suggesting that some nodes in frontal evaluative networks are active early in development. This study presents novel data on neural correlates of face processing in childhood and indicates that preferential amygdala activation for emotional expressions changes with age. PMID:20194512

A six-legged rover for planetary exploration

NASA Technical Reports Server (NTRS)

Simmons, Reid; Krotkov, Eric; Bares, John

1991-01-01

To survive the rigors and isolation of planetary exploration, an autonomous rover must be competent, reliable, and efficient. This paper presents the Ambler, a six-legged robot featuring orthogonal legs and a novel circulating gait, which has been designed for traversal of rugged, unknown environments. An autonomous software system that integrates perception, planning, and real-time control has been developed to walk the Ambler through obstacle strewn terrain. The paper describes the information and control flow of the walking system, and how the design of the mechanism and software combine to achieve competent walking, reliable behavior in the face of unexpected failures, and efficient utilization of time and power.

Panel workload assessment in US primary care: accounting for non-face-to-face panel management activities.

PubMed

Arndt, Brian; Tuan, Wen-Jan; White, Jennifer; Schumacher, Jessica

2014-01-01

An understanding of primary care provider (PCP) workload is an important consideration in establishing optimal PCP panel size. However, no widely acceptable measure of PCP workload exists that incorporates the effort involved with both non-face-to-face patient care activities and face-to-face encounters. Accounting for this gap is critical given the increase in non-face-to-face PCP activities that has accompanied electronic health records (EHRs) (eg, electronic messaging). Our goal was to provide a comprehensive assessment of perceived PCP workload, accounting for aspects of both face-to-face and non-face-to-face encounters. Internal medicine, family medicine, and pediatric PCPs completed a self-administered survey about the perceived workload involved with face-to-face and non-face-to-face panel management activities as well as the perceived challenge associated with caring for patients with particular biomedical, demographic, and psychosocial characteristics (n = 185). Survey results were combined with EHR data at the individual patient and PCP service levels to assess PCP panel workload, accounting for face-to-face and non-face-to-face utilization. Of the multiple face-to-face and non-face-to-face activities associated with routine primary care, PCPs considered hospital admissions, obstetric care, hospital discharges, and new patient preventive health visits to be greater workload than non-face-to-face activities such as telephone calls, electronic communication, generating letters, and medication refills. Total workload within PCP panels at the individual patient level varied by overall health status, and the total workload of non-face-to-face panel management activities associated with routine primary care was greater than the total workload associated with face-to-face encounters regardless of health status. We used PCP survey results coupled with EHR data to assess PCP workload associated with both face-to-face as well as non-face-to-face panel management

Modulation of corticospinal input to the legs by arm and leg cycling in people with incomplete spinal cord injury.

PubMed

Zhou, R; Alvarado, L; Kim, S; Chong, S L; Mushahwar, V K

2017-10-01

The spinal cervico-lumbar interaction during rhythmic movements in humans has recently been studied; however, the role of arm movements in modulating the corticospinal drive to the legs is not well understood. The goals of this study were to investigate the effect of active rhythmic arm movements on the corticospinal drive to the legs ( study 1 ) and assess the effect of simultaneous arm and leg training on the corticospinal pathway after incomplete spinal cord injury (iSCI) ( study 2). In study 1 , neurologically intact (NI) participants or participants with iSCI performed combinations of stationary and rhythmic cycling of the arms and legs while motor evoked potentials (MEPs) were recorded from the vastus lateralis (VL) muscle. In the NI group, arm cycling alone could facilitate the VL MEP amplitude, suggesting that dynamic arm movements strongly modulate the corticospinal pathway to the legs. No significant difference in VL MEP between conditions was found in participants with iSCI. In study 2 , participants with iSCI underwent 12 wk of electrical stimulation-assisted cycling training: one group performed simultaneous arm and leg (A&L) cycling and the other legs-only cycling. MEPs in the tibialis anterior (TA) muscle were compared before and after training. After training, only the A&L group had a significantly larger TA MEP, suggesting increased excitability in the corticospinal pathway. The findings demonstrate the importance of arm movements in modulating the corticospinal drive to the legs and suggest that active engagement of the arms in lower limb rehabilitation may produce better neural regulation and restoration of function. NEW & NOTEWORTHY This study aimed to demonstrate the importance of arm movements in modulating the corticospinal drive to the legs. It provides direct evidence in humans that active movement of the arms could facilitate corticospinal transmission to the legs and, for the first time, shows that facilitation is absent after spinal cord

Informal Face-to-Face Interaction Improves Mood State Reflected in Prefrontal Cortex Activity

PubMed Central

Watanabe, Jun-ichiro; Atsumori, Hirokazu; Kiguchi, Masashi

2016-01-01

Recent progress with wearable sensors has enabled researchers to capture face-to-face interactions quantitatively and given great insight into human dynamics. One attractive field for applying such sensors is the workplace, where the relationship between the face-to-face behaviors of employees and the productivity of the organization has been investigated. One interesting result of previous studies showed that informal face-to-face interaction among employees, captured by wearable sensors that the employees wore, significantly affects their performance. However, the mechanism behind this relationship has not yet been adequately explained, though experiences at the job scene might qualitatively support the finding. We hypothesized that informal face-to-face interaction improves mood state, which in turn affects the task performance. To test this hypothesis, we evaluated the change of mood state before and after break time for two groups of participants, one that spent their breaks alone and one that spent them with other participants, by administering questionnaires and taking brain activity measurements. Recent neuroimaging studies have suggested a significant relationship between mood state and brain activity. Here, we show that face-to-face interaction during breaks significantly improved mood state, which was measured by Profiles of Mood States (POMS). We also observed that the verbal working memory (WM) task performance of participants who did not have face-to-face interaction during breaks decreased significantly. In this paper, we discuss how the change of mood state was evidenced in the prefrontal cortex (PFC) activity accompanied by WM tasks measured by near-infrared spectroscopy (NIRS). PMID:27199715

The effect of sitting and calf activity on leg fluid and snoring.

PubMed

Singh, Bhajan; Yadollahi, Azadeh; Lyons, Owen; Alshaer, Hisham; Bradley, T Douglas

2017-06-01

Prolonged sitting may promote leg fluid retention that redistributes to the neck during sleep and contributes to snoring. This could be attenuated by calf activity while sitting. In 16 healthy non-obese subjects we measured leg fluid volume (LFV) below the knees using bioelectrical impedance while sitting for 4h, snoring using a portable BresoDx™ device, and Mallampati grade. Using a double cross-over study design, subjects were randomized to one of two arms and crossed-over one week later: control arm - no calf exercise while sitting; intervention arm - calf contraction against a pedal resistance while sitting. The effects of sitting±calf activity on LFV and snoring were compared. We found that LFV increased by 216±101.0ml (p<0.0001) after sitting. Calf activity while sitting attenuated LFV by 53.8ml (p<0.0001) and, in all five subjects with severe upper airway narrowing (Mallampati grade IV), reduced snoring duration (from 357±132.9 to 116.2±72.1s/h, p=0.02) suggesting reduced overnight rostral fluid shift to the neck. Copyright © 2017 Elsevier B.V. All rights reserved.

A common neural element receiving rhythmic arm and leg activity as assessed by reflex modulation in arm muscles

PubMed Central

Tazoe, Toshiki; Nakajima, Tsuyoshi; Futatsubashi, Genki; Ohtsuka, Hiroyuki; Suzuki, Shinya; Zehr, E. Paul; Komiyama, Tomoyoshi

2016-01-01

Neural interactions between regulatory systems for rhythmic arm and leg movements are an intriguing issue in locomotor neuroscience. Amplitudes of early latency cutaneous reflexes (ELCRs) in stationary arm muscles are modulated during rhythmic leg or arm cycling but not during limb positioning or voluntary contraction. This suggests that interneurons mediating ELCRs to arm muscles integrate outputs from neural systems controlling rhythmic limb movements. Alternatively, outputs could be integrated at the motoneuron and/or supraspinal levels. We examined whether a separate effect on the ELCR pathways and cortico-motoneuronal excitability during arm and leg cycling is integrated by neural elements common to the lumbo-sacral and cervical spinal cord. The subjects performed bilateral leg cycling (LEG), contralateral arm cycling (ARM), and simultaneous contralateral arm and bilateral leg cycling (A&L), while ELCRs in the wrist flexor and shoulder flexor muscles were evoked by superficial radial (SR) nerve stimulation. ELCR amplitudes were facilitated by cycling tasks and were larger during A&L than during ARM and LEG. A low stimulus intensity during ARM or LEG generated a larger ELCR during A&L than the sum of ELCRs during ARM and LEG. We confirmed this nonlinear increase in single motor unit firing probability following SR nerve stimulation during A&L. Furthermore, motor-evoked potentials following transcranial magnetic and electrical stimulation did not show nonlinear potentiation during A&L. These findings suggest the existence of a common neural element of the ELCR reflex pathway that is active only during rhythmic arm and leg movement and receives convergent input from contralateral arms and legs. PMID:26961103

Lower Limb Symmetry: Comparison of Muscular Power Between Dominant and Nondominant Legs in Healthy Young Adults Associated With Single-Leg-Dominant Sports.

PubMed

Vaisman, Alex; Guiloff, Rodrigo; Rojas, Juan; Delgado, Iris; Figueroa, David; Calvo, Rafael

2017-12-01

Achieving a symmetrical power performance (difference <15%) between lower limbs is generally recommended during sports rehabilitation. However, athletes in single-leg-dominant sports, such as professional soccer players, could develop significant asymmetry between their dominant and nondominant legs, such that symmetry does not act as a viable comparison. To (1) compare maximal muscular power between the dominant and nondominant legs in healthy young adults, (2) evaluate the effect of a single-leg-dominant sport activity performed at the professional level, and (3) propose a parameter of normality for maximal power difference in the lower limbs of this young adult population. Controlled laboratory study. A total of 78 healthy, male, young adults were divided into 2 groups according to sport activity level. Group 1 consisted of 51 nonathletes (mean ± SD age, 20.8 ± 1.5 years; weight, 71.9 ± 10.5 kg) who participated in less than 8 hours a week of recreational physical activity with nonspecific training; group 2 consisted of 27 single-leg-dominant professional soccer players (age, 18.4 ± 0.6 years; weight, 70.1 ± 7.5 kg) who specifically trained and competed at their particular activity 8 hours or more a week. For assessment of maximal leg power, both groups completed the single-leg squat jump test. Dominance was determined when participants completed 2 of 3 specific tests with the same extremity. Statistical analysis included the Student t test. No statistical difference was found for maximal power between dominant and nondominant legs for nonathletes ( t = -1.01, P = .316) or single-leg-dominant professional soccer players ( t = -1.10, P = .281). A majority (95%) of participants studied showed a power difference of less than 15% between their lower extremities. Among young healthy adults, symmetrical power performance is expected between lower extremities independent of the existence of dominance and difference in sport activity level. A less than 15

Comparing Role-Playing Activities in Second Life and Face-to-Face Environments

ERIC Educational Resources Information Center

Gao, Fei; Noh, Jeongmin J.; Koehler, Matthew J.

2009-01-01

This study compared student performances in role-playing activities in both a face-to-face (FTF) environment and a virtual 3D environment, Second Life (SL). We found that students produced a similar amount of communication in the two environments, but the communication styles were different. In SL role-playing activities, students took more…

Activity in Face-Responsive Brain Regions is Modulated by Invisible, Attended Faces: Evidence from Masked Priming

PubMed Central

Eger, Evelyn; Dolan, Raymond; Henson, Richard N.

2009-01-01

It is often assumed that neural activity in face-responsive regions of primate cortex correlates with conscious perception of faces. However, whether such activity occurs without awareness is still debated. Using functional magnetic resonance imaging (fMRI) in conjunction with a novel masked face priming paradigm, we observed neural modulations that could not be attributed to perceptual awareness. More specifically, we found reduced activity in several classic face-processing regions, including the “fusiform face area,” “occipital face area,” and superior temporal sulcus, when a face was preceded by a briefly flashed image of the same face, relative to a different face, even when 2 images of the same face differed. Importantly, unlike most previous studies, which have minimized awareness by using conditions of inattention, the present results occurred when the stimuli (the primes) were attended. By contrast, when primes were perceived consciously, in a long-lag priming paradigm, we found repetition-related activity increases in additional frontal and parietal regions. These data not only demonstrate that fMRI activity in face-responsive regions can be modulated independently of perceptual awareness, but also document where such subliminal face-processing occurs (i.e., restricted to face-responsive regions of occipital and temporal cortex) and to what extent (i.e., independent of the specific image). PMID:18400791

The effects of performing a one-legged bridge with hip abduction and use of a sling on trunk and lower extremity muscle activation in healthy adults.

PubMed

Choi, Kyuju; Bak, Jongwoo; Cho, Minkwon; Chung, Yijung

2016-09-01

[Purpose] This study investigated the changes in the muscle activities of the trunk and lower limbs of healthy adults during a one-legged bridge exercise using a sling, and with the addition of hip abduction. [Subjects and Methods] Twenty-seven healthy individuals participated in this study (14 males and 13 females). The participants were instructed to perform the bridge exercises under five different conditions. Trunk and lower limb muscle activation of the erector spinae (ES), external oblique (EO), gluteus maximus (GM), and biceps femoris (BF) was measured using surface electromyography. Data analysis was performed using the mean scores of three trials performed under each condition. [Results] There was a significant increase in bilateral EO and contralateral GM with the one-legged bridge compared with the one-legged bridge with sling exercise. Muscle activation of the ipsilateral GM and BF was significantly less during the one-legged bridge exercise compared to the one-legged bridge with sling exercise, and was significantly greater during the one-legged bridge with hip abduction compared to the one-legged bridge exercise. The muscle activation of the contralateral GM and BF was significantly greater with the one-legged bridge with hip abduction compared to the general bridge exercise. [Conclusion] With the one-legged bridge with hip abduction, the ipsilateral EO, GM and BF muscle activities were significantly greater than those of the one-legged bridge exercise. The muscle activation of all trunk and contralateral lower extremity muscles increased with the bridge with sling exercises compared with general bridge exercises.

A common neural element receiving rhythmic arm and leg activity as assessed by reflex modulation in arm muscles.

PubMed

Sasada, Syusaku; Tazoe, Toshiki; Nakajima, Tsuyoshi; Futatsubashi, Genki; Ohtsuka, Hiroyuki; Suzuki, Shinya; Zehr, E Paul; Komiyama, Tomoyoshi

2016-04-01

Neural interactions between regulatory systems for rhythmic arm and leg movements are an intriguing issue in locomotor neuroscience. Amplitudes of early latency cutaneous reflexes (ELCRs) in stationary arm muscles are modulated during rhythmic leg or arm cycling but not during limb positioning or voluntary contraction. This suggests that interneurons mediating ELCRs to arm muscles integrate outputs from neural systems controlling rhythmic limb movements. Alternatively, outputs could be integrated at the motoneuron and/or supraspinal levels. We examined whether a separate effect on the ELCR pathways and cortico-motoneuronal excitability during arm and leg cycling is integrated by neural elements common to the lumbo-sacral and cervical spinal cord. The subjects performed bilateral leg cycling (LEG), contralateral arm cycling (ARM), and simultaneous contralateral arm and bilateral leg cycling (A&L), while ELCRs in the wrist flexor and shoulder flexor muscles were evoked by superficial radial (SR) nerve stimulation. ELCR amplitudes were facilitated by cycling tasks and were larger during A&L than during ARM and LEG. A low stimulus intensity during ARM or LEG generated a larger ELCR during A&L than the sum of ELCRs during ARM and LEG. We confirmed this nonlinear increase in single motor unit firing probability following SR nerve stimulation during A&L. Furthermore, motor-evoked potentials following transcranial magnetic and electrical stimulation did not show nonlinear potentiation during A&L. These findings suggest the existence of a common neural element of the ELCR reflex pathway that is active only during rhythmic arm and leg movement and receives convergent input from contralateral arms and legs. Copyright © 2016 the American Physiological Society.

A load-based mechanism for inter-leg coordination in insects

PubMed Central

2017-01-01

Animals rely on an adaptive coordination of legs during walking. However, which specific mechanisms underlie coordination during natural locomotion remains largely unknown. One hypothesis is that legs can be coordinated mechanically based on a transfer of body load from one leg to another. To test this hypothesis, we simultaneously recorded leg kinematics, ground reaction forces and muscle activity in freely walking stick insects (Carausius morosus). Based on torque calculations, we show that load sensors (campaniform sensilla) at the proximal leg joints are well suited to encode the unloading of the leg in individual steps. The unloading coincides with a switch from stance to swing muscle activity, consistent with a load reflex promoting the stance-to-swing transition. Moreover, a mechanical simulation reveals that the unloading can be ascribed to the loading of a specific neighbouring leg, making it exploitable for inter-leg coordination. We propose that mechanically mediated load-based coordination is used across insects analogously to mammals. PMID:29187626

Cohesive taping and short-leg casting in acute low-type ankle sprains in physically active patients.

PubMed

Uslu, Mustafa; Inanmaz, Mustafa E; Ozsahin, Mustafa; Isık, Cengiz; Arıcan, Mehmet; Gecer, Yavuz

2015-07-01

Cohesive taping is commonly used for the prevention or treatment of ankle sprain injuries. Short-leg cast immobilization or splinting is another treatment option in such cases. To determine the clinical efficacy and antiedema effects of cohesive taping and short-leg cast immobilization in acute low-type ankle sprains of physically active patients, we performed a preliminary clinical study to assess objective evidence for edema and functional patient American Orthopaedic Foot and Ankle Society (AOFAS) scores with these alternative treatments. Fifty-nine physically active patients were included: 32 in the taping group and 27 in the short-leg cast group within a year. If a sprain was moderate (grade II) or mild (grade I), we used functional taping or short-leg cast immobilization for 10 days. We evaluated the edema and the functional scores of the injured ankle using the AOFAS Clinical Rating System on days 1, 10, and 100. In each group, edema significantly decreased and AOFAS scores increased indicating that both treatment methods were effective. With the numbers available, no statistically significant difference could be detected. Each treatment method was effective in decreasing the edema and increasing the functional scores of the ankle. At the beginning of treatment, not only the level of edema but also the initial functional scores of the ankle and examinations are important in making decisions regarding the optimal treatment option.

Modelling temporal networks of human face-to-face contacts with public activity and individual reachability

NASA Astrophysics Data System (ADS)

Zhang, Yi-Qing; Cui, Jing; Zhang, Shu-Min; Zhang, Qi; Li, Xiang

2016-02-01

Modelling temporal networks of human face-to-face contacts is vital both for understanding the spread of airborne pathogens and word-of-mouth spreading of information. Although many efforts have been devoted to model these temporal networks, there are still two important social features, public activity and individual reachability, have been ignored in these models. Here we present a simple model that captures these two features and other typical properties of empirical face-to-face contact networks. The model describes agents which are characterized by an attractiveness to slow down the motion of nearby people, have event-triggered active probability and perform an activity-dependent biased random walk in a square box with periodic boundary. The model quantitatively reproduces two empirical temporal networks of human face-to-face contacts which are testified by their network properties and the epidemic spread dynamics on them.

INTRA-RATER RELIABILITY OF THE MULTIPLE SINGLE-LEG HOP-STABILIZATION TEST AND RELATIONSHIPS WITH AGE, LEG DOMINANCE AND TRAINING.

PubMed

Sawle, Leanne; Freeman, Jennifer; Marsden, Jonathan

2017-04-01

Balance is a complex construct, affected by multiple components such as strength and co-ordination. However, whilst assessing an athlete's dynamic balance is an important part of clinical examination, there is no gold standard measure. The multiple single-leg hop-stabilization test is a functional test which may offer a method of evaluating the dynamic attributes of balance, but it needs to show adequate intra-tester reliability. The purpose of this study was to assess the intra-rater reliability of a dynamic balance test, the multiple single-leg hop-stabilization test on the dominant and non-dominant legs. Intra-rater reliability study. Fifteen active participants were tested twice with a 10-minute break between tests. The outcome measure was the multiple single-leg hop-stabilization test score, based on a clinically assessed numerical scoring system. Results were analysed using an Intraclass Correlations Coefficient (ICC 2,1 ) and Bland-Altman plots. Regression analyses explored relationships between test scores, leg dominance, age and training (an alpha level of p = 0.05 was selected). ICCs for intra-rater reliability were 0.85 for the dominant and non-dominant legs (confidence intervals = 0.62-0.95 and 0.61-0.95 respectively). Bland-Altman plots showed scores within two standard deviations. A significant correlation was observed between the dominant and non-dominant leg on balance scores (R 2 =0.49, p<0.05), and better balance was associated with younger participants in their non-dominant leg (R 2 =0.28, p<0.05) and their dominant leg (R 2 =0.39, p<0.05), and a higher number of hours spent training for the non-dominant leg R 2 =0.37, p<0.05). The multiple single-leg hop-stabilisation test demonstrated strong intra-tester reliability with active participants. Younger participants who trained more, have better balance scores. This test may be a useful measure for evaluating the dynamic attributes of balance. 3.

Leg size and muscle functions associated with leg compliance

NASA Technical Reports Server (NTRS)

Convertino, Victor A.; Doerr, Donald F.; Flores, Jose F.; Hoffler, G. Wyckliffe; Buchanan, Paul

1988-01-01

The relationship between the leg compliance and factors related to the size of leg muscle and to physical fitness was investigated in ten healthy subjects. Vascular compliance of the leg, as determined by a mercury strain gauge, was found to be not significantly correlated with any variables associated with physical fitness per se (e.g., peak O2 uptake, calf strength, age, body weight, or body composition. On the other hand, leg compliance correlated with the calf cross-sectional area (CSA) and the calculated calf volume, with the CSA of calf muscle being the most dominant contributing factor (while fat and bone were poor predicators). It is suggested that leg compliance can be lowered by increasing calf muscle mass, thus providing structural support to limit the expansion of leg veins.

Leg CT scan

MedlinePlus

CAT scan - leg; Computed axial tomography scan - leg; Computed tomography scan - leg; CT scan - leg ... CT scan makes detailed pictures of the body very quickly. The test may help look for: An abscess ...

Leg kinematics and kinetics in landing from a single-leg hop for distance. A comparison between dominant and non-dominant leg.

PubMed

van der Harst, J J; Gokeler, A; Hof, A L

2007-07-01

Anterior cruciate ligament (ACL) deficiency can be a major problem for athletes and subsequent reconstruction of the ACL may be indicated if a conservative regimen has failed. After ACL reconstruction signs of abnormality in the use of the leg remain for a long time. It is expected that the landing after a single-leg hop for distance (horizontal hop) might give insight in the differences in kinematics and kinetics between uninjured legs and ACL-reconstructed legs. Before the ACL-reconstructed leg can be compared with the contralateral leg, knowledge of differences between legs of uninjured subjects is needed. Kinematic and kinetic variables of both legs were measured with an optoelectronic system and a force plate and calculated by inverse dynamics. The dominant leg (the leg with biggest horizontal hop distance) and the contralateral leg of nine uninjured subjects were compared. No significant differences were found in most of the kinematic and kinetic variables between dominant leg and contralateral leg of uninjured subjects. Only hop distance and hip extension angles differed significantly. This study suggests that there are no important differences between dominant leg and contralateral leg in healthy subjects. As a consequence, the uninvolved leg of ACL-reconstructed patients can be used as a reference. The observed variables of this study can be used as a reference of normal values and normal differences between legs in healthy subjects.

Dissociation of muscle sympathetic nerve activity and leg vascular resistance in humans

NASA Technical Reports Server (NTRS)

Shoemaker, J. K.; Herr, M. D.; Sinoway, L. I.

2000-01-01

We examined the hypothesis that the increase in inactive leg vascular resistance during forearm metaboreflex activation is dissociated from muscle sympathetic nerve activity (MSNA). MSNA (microneurography), femoral artery mean blood velocity (FAMBV, Doppler), mean arterial pressure (MAP), and heart rate (HR) were assessed during fatiguing static handgrip exercise (SHG, 2 min) followed by posthandgrip ischemia (PHI, 2 min). Whereas both MAP and MSNA increase during SHG, the transition from SHG to PHI is characterized by a transient reduction in MAP but sustained elevation in MSNA, facilitating separation of these factors in vivo. Femoral artery vascular resistance (FAVR) was calculated (MAP/MBV). MSNA increased by 59 +/- 20% above baseline during SHG (P < 0.05) and was 58 +/- 18 and 78 +/- 18% above baseline at 10 and 20 s of PHI, respectively (P < 0.05 vs. baseline). Compared with baseline, FAVR increased 51 +/- 22% during SHG (P < 0.0001) but returned to baseline levels during the first 30 s of PHI, reflecting the changes in MAP (P < 0.005) and not MSNA. It was concluded that control of leg muscle vascular resistance is sensitive to changes in arterial pressure and can be dissociated from sympathetic factors.

Counting to 20: Online Implementation of a Face-to-Face, Elementary Mathematics Methods Problem-Solving Activity

ERIC Educational Resources Information Center

Schwartz, Catherine Stein

2012-01-01

This study describes implementation of the same problem-solving activity in both online and face-to-face environments. The activity, done in the first class period or first module of a K-2 mathematics methods course, was initially used in a face-to-face class and then adapted later for use in an online class. While the task was originally designed…

Muscle sympathetic nerve responses to passive and active one-legged cycling: insights into the contributions of central command.

PubMed

Doherty, Connor J; Incognito, Anthony V; Notay, Karambir; Burns, Matthew J; Slysz, Joshua T; Seed, Jeremy D; Nardone, Massimo; Burr, Jamie F; Millar, Philip J

2018-01-01

The contribution of central command to the peripheral vasoconstrictor response during exercise has been investigated using primarily handgrip exercise. The purpose of the present study was to compare muscle sympathetic nerve activity (MSNA) responses during passive (involuntary) and active (voluntary) zero-load cycling to gain insights into the effects of central command on sympathetic outflow during dynamic exercise. Hemodynamic measurements and contralateral leg MSNA (microneurography) data were collected in 18 young healthy participants at rest and during 2 min of passive and active zero-load one-legged cycling. Arterial baroreflex control of MSNA burst occurrence and burst area were calculated separately in the time domain. Blood pressure and stroke volume increased during exercise ( P < 0.0001) but were not different between passive and active cycling ( P > 0.05). In contrast, heart rate, cardiac output, and total vascular conductance were greater during the first and second minute of active cycling ( P < 0.001). MSNA burst frequency and incidence decreased during passive and active cycling ( P < 0.0001), but no differences were detected between exercise modes ( P > 0.05). Reductions in total MSNA were attenuated during the first ( P < 0.0001) and second ( P = 0.0004) minute of active compared with passive cycling, in concert with increased MSNA burst amplitude ( P = 0.02 and P = 0.005, respectively). The sensitivity of arterial baroreflex control of MSNA burst occurrence was lower during active than passive cycling ( P = 0.01), while control of MSNA burst strength was unchanged ( P > 0.05). These results suggest that central feedforward mechanisms are involved primarily in modulating the strength, but not the occurrence, of a sympathetic burst during low-intensity dynamic leg exercise. NEW & NOTEWORTHY Muscle sympathetic nerve activity burst frequency decreased equally during passive and active cycling, but reductions in total muscle sympathetic nerve

Fiber-type distribution in insect leg muscles parallels similarities and differences in the functional role of insect walking legs.

PubMed

Godlewska-Hammel, Elzbieta; Büschges, Ansgar; Gruhn, Matthias

2017-10-01

Previous studies have demonstrated that myofibrillar ATPase (mATPase) enzyme activity in muscle fibers determines their contraction properties. We analyzed mATPase activities in muscles of the front, middle and hind legs of the orthopteran stick insect (Carausius morosus) to test the hypothesis that differences in muscle fiber types and distributions reflected differences in their behavioral functions. Our data show that all muscles are composed of at least three fiber types, fast, intermediate and slow, and demonstrate that: (1) in the femoral muscles (extensor and flexor tibiae) of all legs, the number of fast fibers decreases from proximal to distal, with a concomitant increase in the number of slow fibers. (2) The swing phase muscles protractor coxae and levator trochanteris, have smaller percentages of slow fibers compared to the antagonist stance muscles retractor coxae and depressor trochanteris. (3) The percentage of slow fibers in the retractor coxae and depressor trochanteris increases significantly from front to hind legs. These results suggest that fiber-type distribution in leg muscles of insects is not identical across leg muscles but tuned towards the specific function of a given muscle in the locomotor system.

Laboratory on legs: an architecture for adjustable morphology with legged robots

NASA Astrophysics Data System (ADS)

Haynes, G. Clark; Pusey, Jason; Knopf, Ryan; Johnson, Aaron M.; Koditschek, Daniel E.

2012-06-01

For mobile robots, the essential units of actuation, computation, and sensing must be designed to fit within the body of the robot. Additional capabilities will largely depend upon a given activity, and should be easily reconfigurable to maximize the diversity of applications and experiments. To address this issue, we introduce a modular architecture originally developed and tested in the design and implementation of the X-RHex hexapod that allows the robot to operate as a mobile laboratory on legs. In the present paper we will introduce the specification, design and very earliest operational data of Canid, an actively driven compliant-spined quadruped whose completely different morphology and intended dynamical operating point are nevertheless built around exactly the same "Lab on Legs" actuation, computation, and sensing infrastructure. We will review as well, more briefly a second RHex variation, the XRL platform, built using the same components.

Microgravity, Mesh-Crawling Legged Robots

NASA Technical Reports Server (NTRS)

Behar, Alberto; Marzwell, Neville; Matthews, Jaret; Richardson, Krandalyn; Wall, Jonathan; Poole, Michael; Foor, David; Rodgers, Damian

2008-01-01

The design, fabrication, and microgravity flight-testing are part of a continuing development of palm-sized mobile robots that resemble spiders (except that they have six legs apiece, whereas a spider has eight legs). Denoted SpiderBots (see figure), they are prototypes of proposed product line of relatively inexpensive walking robots that could be deployed in large numbers to function cooperatively in construction, repair, exploration, search, and rescue activities in connection with exploration of outer space and remote planets.

Autistic Traits and Brain Activation during Face-to-Face Conversations in Typically Developed Adults

PubMed Central

Suda, Masashi; Takei, Yuichi; Aoyama, Yoshiyuki; Narita, Kosuke; Sakurai, Noriko; Fukuda, Masato; Mikuni, Masahiko

2011-01-01

Background Autism spectrum disorders (ASD) are characterized by impaired social interaction and communication, restricted interests, and repetitive behaviours. The severity of these characteristics is posited to lie on a continuum that extends into the general population. Brain substrates underlying ASD have been investigated through functional neuroimaging studies using functional magnetic resonance imaging (fMRI). However, fMRI has methodological constraints for studying brain mechanisms during social interactions (for example, noise, lying on a gantry during the procedure, etc.). In this study, we investigated whether variations in autism spectrum traits are associated with changes in patterns of brain activation in typically developed adults. We used near-infrared spectroscopy (NIRS), a recently developed functional neuroimaging technique that uses near-infrared light, to monitor brain activation in a natural setting that is suitable for studying brain functions during social interactions. Methodology We monitored regional cerebral blood volume changes using a 52-channel NIRS apparatus over the prefrontal cortex (PFC) and superior temporal sulcus (STS), 2 areas implicated in social cognition and the pathology of ASD, in 28 typically developed participants (14 male and 14 female) during face-to-face conversations. This task was designed to resemble a realistic social situation. We examined the correlations of these changes with autistic traits assessed using the Autism-Spectrum Quotient (AQ). Principal Findings Both the PFC and STS were significantly activated during face-to-face conversations. AQ scores were negatively correlated with regional cerebral blood volume increases in the left STS during face-to-face conversations, especially in males. Conclusions Our results demonstrate successful monitoring of brain function during realistic social interactions by NIRS as well as lesser brain activation in the left STS during face-to-face conversations in typically

Autistic traits and brain activation during face-to-face conversations in typically developed adults.

PubMed

Suda, Masashi; Takei, Yuichi; Aoyama, Yoshiyuki; Narita, Kosuke; Sakurai, Noriko; Fukuda, Masato; Mikuni, Masahiko

2011-01-01

Autism spectrum disorders (ASD) are characterized by impaired social interaction and communication, restricted interests, and repetitive behaviours. The severity of these characteristics is posited to lie on a continuum that extends into the general population. Brain substrates underlying ASD have been investigated through functional neuroimaging studies using functional magnetic resonance imaging (fMRI). However, fMRI has methodological constraints for studying brain mechanisms during social interactions (for example, noise, lying on a gantry during the procedure, etc.). In this study, we investigated whether variations in autism spectrum traits are associated with changes in patterns of brain activation in typically developed adults. We used near-infrared spectroscopy (NIRS), a recently developed functional neuroimaging technique that uses near-infrared light, to monitor brain activation in a natural setting that is suitable for studying brain functions during social interactions. We monitored regional cerebral blood volume changes using a 52-channel NIRS apparatus over the prefrontal cortex (PFC) and superior temporal sulcus (STS), 2 areas implicated in social cognition and the pathology of ASD, in 28 typically developed participants (14 male and 14 female) during face-to-face conversations. This task was designed to resemble a realistic social situation. We examined the correlations of these changes with autistic traits assessed using the Autism-Spectrum Quotient (AQ). Both the PFC and STS were significantly activated during face-to-face conversations. AQ scores were negatively correlated with regional cerebral blood volume increases in the left STS during face-to-face conversations, especially in males. Our results demonstrate successful monitoring of brain function during realistic social interactions by NIRS as well as lesser brain activation in the left STS during face-to-face conversations in typically developed participants with higher levels of autistic

Characteristics of Lower Leg Muscle Activity in Patients with Cerebral Palsy during Cycling on an Ergometer.

PubMed

Roy, Susmita; Alves-Pinto, Ana; Lampe, Renée

2018-01-01

Cycling on ergometer is often part of rehabilitation programs for patients with cerebral palsy (CP). The present study analyzed activity patterns of individual lower leg muscle during active cycling on ergometer in patients with CP and compared them to similar recordings in healthy participants. Electromyographic (EMG) recordings of lower leg muscle activity were collected from 14 adult patients and 10 adult healthy participants. Activity of the following muscles was recorded: Musculus tibialis anterior, Musculus gastrocnemius, Musculus rectus femoris, and Musculus biceps femoris. Besides qualitative analysis also quantitative analysis of individual muscle activity was performed by computing the coefficient of variation of EMG signal amplitude. More irregular EMG patterns were observed in patients in comparison to healthy participants: agonist-antagonist cocontractions were more frequent, muscle activity measured at specific points of the cycle path was more variable, and dynamic range of muscle activity along the cycle path was narrower in patients. Hypertonicity was also more frequent in patients. Muscle activity patterns during cycling differed substantially across patients. It showed irregular nature and occasional sharp high peaks. Dynamic range was also narrower than in controls. Observations underline the need for individualized cycling training to optimize rehabilitation effects.

Gender differences in active musculoskeletal stiffness. Part II. Quantification of leg stiffness during functional hopping tasks.

PubMed

Granata, K P; Padua, D A; Wilson, S E

2002-04-01

Leg stiffness was compared between age-matched males and females during hopping at preferred and controlled frequencies. Stiffness was defined as the linear regression slope between the vertical center of mass (COM) displacement and ground-reaction forces recorded from a force plate during the stance phase of the hopping task. Results demonstrate that subjects modulated the vertical displacement of the COM during ground contact in relation to the square of hopping frequency. This supports the accuracy of the spring-mass oscillator as a representative model of hopping. It also maintained peak vertical ground-reaction load at approximately three times body weight. Leg stiffness values in males (33.9+/-8.7 kN/m) were significantly (p<0.01) greater than in females (26.3+/-6.5 kN/m) at each of three hopping frequencies, 3.0, 2.5 Hz, and a preferred hopping rate. In the spring-mass oscillator model leg stiffness and body mass are related to the frequency of motion. Thus male subjects necessarily recruited greater leg stiffness to drive their heavier body mass at the same frequency as the lighter female subjects during the controlled frequency trials. However, in the preferred hopping condition the stiffness was not constrained by the task because frequency was self-selected. Nonetheless, both male and female subjects hopped at statistically similar preferred frequencies (2.34+/-0.22 Hz), therefore, the females continued to demonstrate less leg stiffness. Recognizing the active muscle stiffness contributes to biomechanical stability as well as leg stiffness, these results may provide insight into the gender bias in risk of musculoskeletal knee injury.

[Paraesthesia in the legs].

PubMed

Eisensehr, Ilonka

2007-10-18

Paraesthesia in the legs can have numerous causes. In addition to the restless legs syndrome, other primary causes include venous insufficiency in the leg, propriospinal myoclonus, nocturnal leg cramps, peripheral polyneuropathy that affects mostly the legs or neuroleptic drug-induced akathisia. Through detailed questioning of the patient, restless legs syndrome can be specifically distinguished from the other named differential diagnoses.

Alcoholism and Dampened Temporal Limbic Activation to Emotional Faces

PubMed Central

Marinkovic, Ksenija; Oscar-Berman, Marlene; Urban, Trinity; O’Reilly, Cara E.; Howard, Julie A.; Sawyer, Kayle; Harris, Gordon J.

2013-01-01

Background Excessive chronic drinking is accompanied by a broad spectrum of emotional changes ranging from apathy and emotional flatness to deficits in comprehending emotional information, but their neural bases are poorly understood. Methods Emotional abnormalities associated with alcoholism were examined with functional magnetic resonance imaging in abstinent long-term alcoholic men in comparison to healthy demographically matched controls. Participants were presented with emotionally valenced words and photographs of faces during deep (semantic) and shallow (perceptual) encoding tasks followed by recognition. Results Overall, faces evoked stronger activation than words, with the expected material-specific laterality (left hemisphere for words, and right for faces) and depth of processing effects. However, whereas control participants showed stronger activation in the amygdala and hippocampus when viewing faces with emotional (relative to neutral) expressions, the alcoholics responded in an undifferentiated manner to all facial expressions. In the alcoholic participants, amygdala activity was inversely correlated with an increase in lateral prefrontal activity as a function of their behavioral deficits. Prefrontal modulation of emotional function as a compensation for the blunted amygdala activity during a socially relevant face appraisal task is in agreement with a distributed network engagement during emotional face processing. Conclusions Deficient activation of amygdala and hippocampus may underlie impaired processing of emotional faces associated with long-term alcoholism and may be a part of the wide array of behavioral problems including disinhibition, concurring with previously documented interpersonal difficulties in this population. Furthermore, the results suggest that alcoholics may rely on prefrontal rather than temporal limbic areas in order to compensate for reduced limbic responsivity and to maintain behavioral adequacy when faced with emotionally

Alcoholism and dampened temporal limbic activation to emotional faces.

PubMed

Marinkovic, Ksenija; Oscar-Berman, Marlene; Urban, Trinity; O'Reilly, Cara E; Howard, Julie A; Sawyer, Kayle; Harris, Gordon J

2009-11-01

Excessive chronic drinking is accompanied by a broad spectrum of emotional changes ranging from apathy and emotional flatness to deficits in comprehending emotional information, but their neural bases are poorly understood. Emotional abnormalities associated with alcoholism were examined with functional magnetic resonance imaging in abstinent long-term alcoholic men in comparison to healthy demographically matched controls. Participants were presented with emotionally valenced words and photographs of faces during deep (semantic) and shallow (perceptual) encoding tasks followed by recognition. Overall, faces evoked stronger activation than words, with the expected material-specific laterality (left hemisphere for words, and right for faces) and depth of processing effects. However, whereas control participants showed stronger activation in the amygdala and hippocampus when viewing faces with emotional (relative to neutral) expressions, the alcoholics responded in an undifferentiated manner to all facial expressions. In the alcoholic participants, amygdala activity was inversely correlated with an increase in lateral prefrontal activity as a function of their behavioral deficits. Prefrontal modulation of emotional function as a compensation for the blunted amygdala activity during a socially relevant face appraisal task is in agreement with a distributed network engagement during emotional face processing. Deficient activation of amygdala and hippocampus may underlie impaired processing of emotional faces associated with long-term alcoholism and may be a part of the wide array of behavioral problems including disinhibition, concurring with previously documented interpersonal difficulties in this population. Furthermore, the results suggest that alcoholics may rely on prefrontal rather than temporal limbic areas in order to compensate for reduced limbic responsivity and to maintain behavioral adequacy when faced with emotionally or socially challenging situations.

Active sleep is associated with the face preference in the newborns who familiarized with a responsive face.

PubMed

Cecchini, Marco; Iannoni, Maria Elena; Aceto, Paola; Baroni, Eleonora; Di Vito, Cinzia; Lai, Carlo

2017-11-01

Aim of this study was to investigate the preferential looking behaviour, subsequent to a familiarization task (8-min) with a previously responsive or motionless face, before and after a sleep cycle. Moreover, the role of the active sleep in memory consolidation of the responsive or motionless faces was explored. Hypotheses were that the newborns undergoing a motionless familiarization will exhibit a novelty effect (preference for the novel face) whereas the newborns undergoing a responsive familiarization will show a familiarity effect (preference for the known face) before and after the sleep cycle; moreover, the amount of active sleep will be associated with the looking time at the known face after a sleep cycle. Forty-five healthy full-term newborns were randomly assigned to two groups (group 1: motionless-familiarization and group 2: responsive-familiarization); in both groups newborns were video-recorded during four post-familiarization face-preference tasks, two of them performed before and two after a sleep cycle. During the pre-sleep-trials, there was not a significant preference for one face in both groups. During the post-sleep trials, the newborns showed a clear preference for the novel face. This effect was more evident in group 1. Only in group 2 there was a significant positive correlation between the active sleep duration and the looking duration at the known-face during the post-sleep trials (r=0.41; p=0.040). Multiple regression confirmed that only in the group 2 the total duration of the active sleep was associated with the looking duration at the known-face during the post-sleep trials (Adjusted R 2 =0.13; β=0.41; t=2.2; p=0.040). Findings showed that in newborns the face representation can be recalled after a sleep cycle. Moreover, the amount of the active sleep predicted the post-sleep looking toward the known-face only in the newborns who interactively familiarized with the face. Copyright © 2017 Elsevier Inc. All rights reserved.

Don't break a leg: running birds from quail to ostrich prioritise leg safety and economy on uneven terrain.

PubMed

Birn-Jeffery, Aleksandra V; Hubicki, Christian M; Blum, Yvonne; Renjewski, Daniel; Hurst, Jonathan W; Daley, Monica A

2014-11-01

Cursorial ground birds are paragons of bipedal running that span a 500-fold mass range from quail to ostrich. Here we investigate the task-level control priorities of cursorial birds by analysing how they negotiate single-step obstacles that create a conflict between body stability (attenuating deviations in body motion) and consistent leg force-length dynamics (for economy and leg safety). We also test the hypothesis that control priorities shift between body stability and leg safety with increasing body size, reflecting use of active control to overcome size-related challenges. Weight-support demands lead to a shift towards straighter legs and stiffer steady gait with increasing body size, but it remains unknown whether non-steady locomotor priorities diverge with size. We found that all measured species used a consistent obstacle negotiation strategy, involving unsteady body dynamics to minimise fluctuations in leg posture and loading across multiple steps, not directly prioritising body stability. Peak leg forces remained remarkably consistent across obstacle terrain, within 0.35 body weights of level running for obstacle heights from 0.1 to 0.5 times leg length. All species used similar stance leg actuation patterns, involving asymmetric force-length trajectories and posture-dependent actuation to add or remove energy depending on landing conditions. We present a simple stance leg model that explains key features of avian bipedal locomotion, and suggests economy as a key priority on both level and uneven terrain. We suggest that running ground birds target the closely coupled priorities of economy and leg safety as the direct imperatives of control, with adequate stability achieved through appropriately tuned intrinsic dynamics. © 2014. Published by The Company of Biologists Ltd.

Don't break a leg: running birds from quail to ostrich prioritise leg safety and economy on uneven terrain

PubMed Central

Birn-Jeffery, Aleksandra V.; Hubicki, Christian M.; Blum, Yvonne; Renjewski, Daniel; Hurst, Jonathan W.; Daley, Monica A.

2014-01-01

Cursorial ground birds are paragons of bipedal running that span a 500-fold mass range from quail to ostrich. Here we investigate the task-level control priorities of cursorial birds by analysing how they negotiate single-step obstacles that create a conflict between body stability (attenuating deviations in body motion) and consistent leg force–length dynamics (for economy and leg safety). We also test the hypothesis that control priorities shift between body stability and leg safety with increasing body size, reflecting use of active control to overcome size-related challenges. Weight-support demands lead to a shift towards straighter legs and stiffer steady gait with increasing body size, but it remains unknown whether non-steady locomotor priorities diverge with size. We found that all measured species used a consistent obstacle negotiation strategy, involving unsteady body dynamics to minimise fluctuations in leg posture and loading across multiple steps, not directly prioritising body stability. Peak leg forces remained remarkably consistent across obstacle terrain, within 0.35 body weights of level running for obstacle heights from 0.1 to 0.5 times leg length. All species used similar stance leg actuation patterns, involving asymmetric force–length trajectories and posture-dependent actuation to add or remove energy depending on landing conditions. We present a simple stance leg model that explains key features of avian bipedal locomotion, and suggests economy as a key priority on both level and uneven terrain. We suggest that running ground birds target the closely coupled priorities of economy and leg safety as the direct imperatives of control, with adequate stability achieved through appropriately tuned intrinsic dynamics. PMID:25355848

Age Effects on Trustworthiness Activation and Trust Biases in Face Perception.

PubMed

Cassidy, Brittany S; Boucher, Kathryn L; Lanie, Shelby T; Krendl, Anne C

2018-05-26

Older adults evaluate faces as being more trustworthy than do younger adults. The present work examined whether aging is associated with changes in the dynamic activation of trustworthiness categories toward faces, and if category activation relates to enhanced trust. Younger and older adults categorized faces as trustworthy or untrustworthy while computer mouse trajectories were recorded to measure dynamic category activation. Older, but not younger, adults had more dynamic category activation (i.e., trustworthy and untrustworthy) when they viewed untrustworthy versus trustworthy faces. This tendency predicted a bias (pronounced with age) toward evaluating faces as being trustworthy. A pronounced trust bias in aging may be related to greater dynamic activation of trustworthiness (versus untrustworthiness) when perceiving faces.

Dynamic postural stability for double-leg drop landing.

PubMed

Niu, Wenxin; Zhang, Ming; Fan, Yubo; Zhao, Qinping

2013-01-01

Dynamic postural stability has been widely studied for single-leg landing, but seldom considered for double-leg landing. This study aimed to evaluate the dynamic postural stability and the influence mechanism of muscle activities during double-leg drop landing. Eight recreationally active males and eight recreationally active females participated in this study and dropped individually from three heights (0.32 m, 0.52 m, and 0.72 m). Ground reaction force was recorded to calculate the time to stabilisation. Electromyographic activities were recorded for selected lower-extremity muscles. A multivariate analysis of variance was carried out and no significant influence was found in time to stabilisation between genders or limb laterals (P > 0.05). With increasing drop height, time to stabilisation decreased significantly in two horizontal directions and the lower-extremity muscle activities were enhanced. Vertical time to stabilisation was not significantly influenced by drop height. Dynamic postural stability improved by neuromuscular change more than that required due to the increase of drop height. Double-leg landing on level ground is a stable movement, and the body would often be injured before dynamic postural stability is impaired. It is understandable to protect tissues from mechanical injuries by the sacrifice of certain dynamic postural stability in the design of protective devices or athlete training.

33 CFR 147.809 - Mars Tension Leg Platform safety zone.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Mars Tension Leg Platform safety... SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.809 Mars Tension Leg Platform safety zone. (a) Description. The Mars Tension Leg Platform (Mars TLP) is located at position 28°10′10.29...

33 CFR 147.809 - Mars Tension Leg Platform safety zone.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Mars Tension Leg Platform safety... SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.809 Mars Tension Leg Platform safety zone. (a) Description. The Mars Tension Leg Platform (Mars TLP) is located at position 28°10′10.29...

33 CFR 147.809 - Mars Tension Leg Platform safety zone.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Mars Tension Leg Platform safety... SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.809 Mars Tension Leg Platform safety zone. (a) Description. The Mars Tension Leg Platform (Mars TLP) is located at position 28°10′10.29...

33 CFR 147.809 - Mars Tension Leg Platform safety zone.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Mars Tension Leg Platform safety... SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.809 Mars Tension Leg Platform safety zone. (a) Description. The Mars Tension Leg Platform (Mars TLP) is located at position 28°10′10.29...

33 CFR 147.809 - Mars Tension Leg Platform safety zone.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Mars Tension Leg Platform safety... SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.809 Mars Tension Leg Platform safety zone. (a) Description. The Mars Tension Leg Platform (Mars TLP) is located at position 28°10′10.29...

How performing a repetitive one-legged stance modifies two-legged postural control.

PubMed

Burdet, Cyril; Vuillerme, Nicolas; Rougier, Patrice R

2011-10-01

The proprioceptive cues in the control of movement is recognized as playing a major role in postural control. However, little is known about its possible increased contribution to postural control consecutive to repetitive muscular activations. To test this, the short-term effects induced by a 1-legged exercise on 2-legged postural control with the eyes closed were assessed in healthy subjects. The center-of-pressure (CP) displacements obtained using a force platform were split into 2 elementary movements: center-of-gravity vertical projection (CGv) and the difference (CP - CGv). These movements assessed the net postural performance and the level of neuromuscular activity, respectively, and were processed afterward (a) through variances, mean velocity, and the average surface covered by the trajectories and (b) a fractional Brownian motion (fBm) modeling. The latter provides further information about how much the subject controls the movements and the spatiotemporal relation between the successive control mechanisms. No difference was found using the classical parameters. In contrast, fBm parameters showed statistically significant changes in postural control after 1-legged exercises: The spatial and temporal coordinates of the transition points for the CG movements along the anteroposterior axis are decreased. Because the body movement control does not rely on visual or vestibular cues, this ability to trigger the corrective process of the CG movements more quickly in the postexercise condition and once a more reduced distance has been covered emphasizes how prior muscular activation improves body movement detection. As a general rule, these data show that the motor systems control body motions better after repetitive stimulation of the sensory cues. These insights should be of interest in physical activities based on a precise muscular length control.

Not letting the left leg know what the right leg is doing: limb-specific locomotor adaptation to sensory-cue conflict.

PubMed

Durgin, Frank H; Fox, Laura F; Hoon Kim, Dong

2003-11-01

We investigated the phenomenon of limb-specific locomotor adaptation in order to adjudicate between sensory-cue-conflict theory and motor-adaptation theory. The results were consistent with cue-conflict theory in demonstrating that two different leg-specific hopping aftereffects are modulated by the presence of conflicting estimates of self-motion from visual and nonvisual sources. Experiment 1 shows that leg-specific increases in forward drift during attempts to hop in place on one leg while blindfolded vary according to the relationship between visual information and motor activity during an adaptation to outdoor forward hopping. Experiment 2 shows that leg-specific changes in performance on a blindfolded hopping-to-target task are similarly modulated by the presence of cue conflict during adaptation to hopping on a treadmill. Experiment 3 shows that leg-specific aftereffects from hopping additionally produce inadvertent turning during running in place while blindfolded. The results of these experiments suggest that these leg-specific locomotor aftereffects are produced by sensory-cue conflict rather than simple motor adaptation.

The influence of changes in trunk and pelvic posture during single leg standing on hip and thigh muscle activation in a pain free population.

PubMed

Prior, Simon; Mitchell, Tim; Whiteley, Rod; O'Sullivan, Peter; Williams, Benjamin K; Racinais, Sebastien; Farooq, Abdulaziz

2014-03-27

Thigh muscle injuries commonly occur during single leg loading tasks and patterns of muscle activation are thought to contribute to these injuries. The influence trunk and pelvis posture has on hip and thigh muscle activation during single leg stance is unknown and was investigated in a pain free population to determine if changes in body posture result in consistent patterns of changes in muscle activation. Hip and thigh muscle activation patterns were compared in 22 asymptomatic, male subjects (20-45 years old) in paired functionally relevant single leg standing test postures: Anterior vs. Posterior Trunk Sway; Anterior vs. Posterior Pelvic Rotation; Left vs. Right Trunk Shift; and Pelvic Drop vs. Raise. Surface EMG was collected from eight hip and thigh muscles calculating Root Mean Square. EMG was normalized to an "upright standing" reference posture. Repeated measures ANOVA was performed along with associated F tests to determine if there were significant differences in muscle activation between paired test postures. In right leg stance, Anterior Trunk Sway (compared to Posterior Sway) increased activity in posterior sagittal plane muscles, with a concurrent deactivation of anterior sagittal plane muscles (p: 0.016 - <0.001). Lateral hip abductor muscles increased activation during Left Trunk Shift (compared to Right) (p :≤ 0.001). Lateral Pelvic Drop (compared to Raise) decreased activity in hip abductors and increased hamstring, adductor longus and vastus lateralis activity (p: 0.037 - <0.001). Changes in both trunk and pelvic posture during single leg stance generally resulted in large, predictable changes in hip and thigh muscle activation in asymptomatic young males. Changes in trunk position in the sagittal plane and pelvis position in the frontal plane had the greatest effect on muscle activation. Investigation of these activation patterns in clinical populations such as hip and thigh muscle injuries may provide important insights into injury

Restless legs syndrome mimicking S1 radiculopathy.

PubMed

Zambelis, Th; Wolgamuth, B R; Papoutsi, S N; Economou, N T

2016-01-01

Α case of a chronic idiopathic form of a severe type of Restless Legs Syndrome (RLS), which developed during pregnancy and persisted after this, misdiagnosed for 34 years as radiculopathy S1, is reported. In spite of the thorough clinical and laboratory investigation, in addition to constant changes of the therapeutic approach, the diagnosis of S1 radiculopathy could not be confirmed, resulting in a chronic clinical course; the latter was characterized by relapses and remissions not attributed or linked in any way to the treatment (various types of). In fact, it was due to a routine workup in a sleep clinic, where the patient was referred because of a coincident chronic insomnia (Restless Legs Syndrome is a known and important cause of insomnia/chronic insomnia), which resulted in a proper diagnosis and treatment of this case. With the use of Restless Legs Syndrome appropriate treatment (Pramipexole 0.18 mg taken at bedtime, a dopaminergic agent and Level A recommended drug for Restless Legs Syndrome) an excellent response and immediate elimination of symptoms was achieved. Restless Legs Syndrome may present with a variety of symptoms (with the most prominent shortly being reported with the acronym URGE: Urge to move the legs usually associated with unpleasant leg sensations, Rest induces symptoms, Getting active brings relief, Evening and night deteriorate symptoms); given the fact that Restless Legs Syndrome presents with a great variety and heterogeneity of symptoms (mostly pain, dysesthesia and paresthesia), which may occur in several other diseases (the so called "RLS mimics"), proper diagnosis of Restless Legs Syndrome usually fails. Restless Legs Syndrome misinterpreted as S1 radiculopathy, to the best of our knowledge, has not been reported yet in the literature. Here, case history, clinical course and common RLS mimics are presented. Different forms of Restless Legs Syndrome manifestations, which are commonly -as in this case- misinterpreted due to their

The Lindsay Leg Club: supporting the NHS to provide leg ulcer care.

PubMed

McKenzie, Morag

2013-06-01

Public health services will need to cope with additional demands due to an ageing society and the increasing prevalence of chronic conditions. Lower-limb ulceration is a long-term, life-changing condition and leg ulcer management can be challenging for nursing staff. The Lindsay Leg Club model is a unique partnership between community nurses, members and the local community, which provides quality of care and empowerment for patients with leg ulcers, while also supporting and educating nursing staff. The Leg Club model works in accord with core themes of Government and NHS policy. Patient feedback on the Leg Club model is positive and the Leg Clubs provide a service to members which is well accepted by patients, yet is more economically efficient than the traditional district nursing practice of home visits. Lindsay Leg Clubs provide a valuable support service to the NHS in delivering improved quality of care while improving efficiency.

The effects of surface condition on abdominal muscle activity during single-legged hold exercise.

PubMed

Ha, Sung-min; Oh, Jae-seop; Jeon, In-cheol; Kwon, Oh-yun

2015-02-01

To treat low-back pain, various spinal stability exercises are commonly used to improve trunk muscle function and strength. Because human movement for normal daily activity occurs in multi-dimensions, the importance of exercise in multi-dimensions or on unstable surfaces has been emphasized. Recently, a motorized rotating platform (MRP) for facilitating multi-dimensions dynamic movement was introduced for clinical use. However, the abdominal muscle activity with this device has not been reported. The purpose of this study was to compare the abdominal muscle activity (rectus abdominis, external and internal oblique muscles) during an active single-leg-hold (SLH) exercise on a floor (stable surface), foam roll, and motorized rotating platform (MRP). Thirteen healthy male subjects participated in this study. Using electromyography, the abdominal muscle activity was measured while the subjects performed SLH exercises on floor (stable surface), foam roll, and MRP. There were significant differences in the abdominal muscle activities among conditions (P<.05), except for left EO (P>.05) (Fig. 2). After the Bonferroni correction, however, no significant differences among conditions remained, except for differences in both side IO muscle activity between the floor and foam roll conditions (padj<0.017). The findings suggest that performing the SLH exercises on a foam roll and MRP is more effective increased activities of both side of RA and IO, and Rt. EO compared to floor condition. However, there were no significant differences in abdominal muscles activity in the multiple comparison between conditions (mean difference were smaller than the standard deviation in the abdominal muscle activities) (padj>0.017), except for differences in both side IO muscle activity between the floor (stable surface) and foam roll (padj<0.017) (effect size: 0.79/0.62 (non-supporting/supporting leg) for foam-roll versus floor). Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of wearing lower leg compression sleeves on locomotion economy.

PubMed

Kurz, Eduard; Anders, Christoph

2018-09-01

The purpose of this investigation was to assess the effect of compression sleeves on muscle activation cost during locomotion. Twenty-two recreationally active men (age: 25 ± 3 years) ran on a treadmill at four different speeds (ordered sequence of 2.8, 3.3, 2.2, and 3.9 m/s). The tests were performed without (control situation, CON) and while wearing specially designed lower leg compression sleeves (SL). Myoelectric activity of five lower leg muscles (tibialis anterior, fibularis longus, lateral and medial head of gastrocnemius, and soleus) was captured using Surface EMG. To assess muscle activation cost, the cumulative muscle activity per distance travelled (CMAPD) of the CON and SL situations was determined. Repeated measures analyses of variance were performed separately for each muscle. The analyses revealed a reduced lower leg muscle activation cost with respect to test situation for SL for all muscles (p < 0.05, η p 2  > 0.18). The respective significant reductions of CMAPD values during SL ranged between 4% and 16% and were largest at 2.8 m/s. The findings presented point towards an improved muscle activation cost while wearing lower leg compression sleeves during locomotion that have potential to postpone muscle fatigue.

Abnormal activation of the social brain during face perception in autism.

PubMed

Hadjikhani, Nouchine; Joseph, Robert M; Snyder, Josh; Tager-Flusberg, Helen

2007-05-01

ASD involves a fundamental impairment in processing social-communicative information from faces. Several recent studies have challenged earlier findings that individuals with autism spectrum disorder (ASD) have no activation of the fusiform gyrus (fusiform face area, FFA) when viewing faces. In this study, we examined activation to faces in the broader network of face-processing modules that comprise what is known as the social brain. Using 3T functional resonance imaging, we measured BOLD signal changes in 10 ASD subjects and 7 healthy controls passively viewing nonemotional faces. We replicated our original findings of significant activation of face identity-processing areas (FFA and inferior occipital gyrus, IOG) in ASD. However, in addition, we identified hypoactivation in a more widely distributed network of brain areas involved in face processing [including the right amygdala, inferior frontal cortex (IFC), superior temporal sulcus (STS), and face-related somatosensory and premotor cortex]. In ASD, we found functional correlations between a subgroup of areas in the social brain that belong to the mirror neuron system (IFC, STS) and other face-processing areas. The severity of the social symptoms measured by the Autism Diagnostic Observation Schedule was correlated with the right IFC cortical thickness and with functional activation in that area. When viewing faces, adults with ASD show atypical patterns of activation in regions forming the broader face-processing network and social brain, outside the core FFA and IOG regions. These patterns suggest that areas belonging to the mirror neuron system are involved in the face-processing disturbances in ASD.

The Relationship among Leg Strength, Leg Power and Alpine Skiing Success.

ERIC Educational Resources Information Center

Gettman, Larry R.; Huckel, Jack R.

The purpose of this study was to relate leg strength and power to alpine skiing success as measured by FIS points. Isometric leg strength was represented by the knee extension test described by Clarke. Leg power was measured by the vertical jump test and the Margaria-Kalamen stair run. Results in the strength and power tests were correlated with…

Voluntary Movement Frequencies in Submaximal One- and Two-Legged Knee Extension Exercise and Pedaling

PubMed Central

Stang, Julie; Wiig, Håvard; Hermansen, Marte; Hansen, Ernst Albin

2016-01-01

Understanding of behavior and control of human voluntary rhythmic stereotyped leg movements is useful in work to improve performance, function, and rehabilitation of exercising, healthy, and injured humans. The present study aimed at adding to the existing understanding within this field. To pursue the aim, correlations between freely chosen movement frequencies in relatively simple, single-joint, one- and two-legged knee extension exercise were investigated. The same was done for more complex, multiple-joint, one- and two-legged pedaling. These particular activities were chosen because they could be considered related to some extent, as they shared a key aspect of knee extension, and because they at the same time were different. The activities were performed at submaximal intensities, by healthy individuals (n = 16, thereof eight women; 23.4 ± 2.7 years; 1.70 ± 0.11 m; 68.6 ± 11.2 kg). High and fair correlations (R-values of 0.99 and 0.75) occurred between frequencies generated with the dominant leg and the nondominant leg during knee extension exercise and pedaling, respectively. Fair to high correlations (R-values between 0.71 and 0.95) occurred between frequencies performed with each of the two legs in an activity, and the two-legged frequency performed in the same type of activity. In general, the correlations were higher for knee extension exercise than for pedaling. Correlations between knee extension and pedaling frequencies were of modest occurrence. The correlations between movement frequencies generated separately by each of the legs might be interpreted to support the following working hypothesis, which was based on existing literature. It is likely that involved central pattern generators (CPGs) of the two legs share a common frequency generator or that separate frequency generators of each leg are attuned via interneuronal connections. Further, activity type appeared to be relevant. Thus, the apparent common rhythmogenesis for the two legs appeared

Cardiovascular control during concomitant dynamic leg exercise and static arm exercise in humans

PubMed Central

Strange, S

1999-01-01

Skeletal muscle blood flow is thought to be determined by a balance between sympathetic vasoconstriction and metabolic vasodilatation. The purpose of this study was to assess the importance of high levels of sympathetic vasoconstrictor activity in control of blood flow to human skeletal muscle during dynamic exercise.Muscle sympathetic nerve activity to the exercising leg was increased by static or static ischaemic arm exercise added to on-going dynamic leg exercise. Ten subjects performed light (20 W) or moderate (40 W) dynamic knee extension for 6 min with one leg alone or concomitant with bilateral static handgrip at 20% of maximal voluntary contraction force with or without forearm muscle ischaemia or post-exercise forearm muscle ischaemia.Muscle sympathetic nerve activity was measured by microneurography (peroneal nerve) and leg muscle blood flow by a constant infusion thermodilution technique (femoral vein).Activation of an exercise pressor reflex from the arms, causing a 2- to 4-fold increase in muscle sympathetic nerve activity and a 15–32% increase in mean arterial blood pressure, did not affect blood flow to the dynamically exercising leg muscles at any level of leg exercise. Leg vascular conductance was reduced in line with the higher perfusion pressure.The results demonstrate that the vasoconstrictor effects of high levels of muscle sympathetic nerve activity does not affect blood flow to human skeletal muscle exercising at moderate intensities. One question remaining is whether the observed decrease in muscle vascular conductance is the result of sympathetic vasoconstriction or metabolic autoregulation of muscle blood flow. PMID:9831733

Ankle muscle activity modulation during single-leg stance differs between children, young adults and seniors.

PubMed

Kurz, Eduard; Faude, Oliver; Roth, Ralf; Zahner, Lukas; Donath, Lars

2018-02-01

Incomplete maturation and aging-induced declines of the neuromuscular system affect postural control both in children and older adults and lead to high fall rates. Age-specific comparisons of the modulation of ankle muscle activation and behavioral center of pressure (COP) indices during upright stance have been rarely conducted. The objective of the present study was to quantify aging effects on a neuromuscular level. Thus, surface electromyography (SEMG) modulation and co-activity of ankle muscles during single-leg standing was compared in healthy children, young adults and seniors. Postural steadiness (velocity and mean sway frequency of COP), relative muscle activation (SEMG modulation) and co-activation of two ankle muscles (tibialis anterior, TA; soleus, SO) were examined during single-leg stance in 19 children [age, 9.7 (SD 0.5) years], 30 adults [23.3 (1.5) years] and 29 seniors [62.7 (6.1) years]. Velocity of COP in medio-lateral and anterior-posterior directions, mean sway frequency in anterior-posterior direction, relative muscle activation (TA and SO) and co-activation revealed large age effects (P < 0.003, η p 2  > 0.14). Post-hoc comparisons indicated higher COP velocities, anterior-posterior frequencies, relative SO activation and co-activation in children and seniors when compared with adults. Relative TA activation was higher in children and adults compared with seniors (P < 0.001). Increased postural sway in children and seniors seems to be counteracted with higher TA/SO co-activity and SO modulation. However, TA modulation is higher in children and adults, whereas seniors' TA modulation capacity is diminished. An aging-induced decline of TA motor units might account for deteriorations of TA modulation in seniors.

Reconstructing Perceived and Retrieved Faces from Activity Patterns in Lateral Parietal Cortex.

PubMed

Lee, Hongmi; Kuhl, Brice A

2016-06-01

Recent findings suggest that the contents of memory encoding and retrieval can be decoded from the angular gyrus (ANG), a subregion of posterior lateral parietal cortex. However, typical decoding approaches provide little insight into the nature of ANG content representations. Here, we tested whether complex, multidimensional stimuli (faces) could be reconstructed from ANG by predicting underlying face components from fMRI activity patterns in humans. Using an approach inspired by computer vision methods for face recognition, we applied principal component analysis to a large set of face images to generate eigenfaces. We then modeled relationships between eigenface values and patterns of fMRI activity. Activity patterns evoked by individual faces were then used to generate predicted eigenface values, which could be transformed into reconstructions of individual faces. We show that visually perceived faces were reliably reconstructed from activity patterns in occipitotemporal cortex and several lateral parietal subregions, including ANG. Subjective assessment of reconstructed faces revealed specific sources of information (e.g., affect and skin color) that were successfully reconstructed in ANG. Strikingly, we also found that a model trained on ANG activity patterns during face perception was able to successfully reconstruct an independent set of face images that were held in memory. Together, these findings provide compelling evidence that ANG forms complex, stimulus-specific representations that are reflected in activity patterns evoked during perception and remembering. Neuroimaging studies have consistently implicated lateral parietal cortex in episodic remembering, but the functional contributions of lateral parietal cortex to memory remain a topic of debate. Here, we used an innovative form of fMRI pattern analysis to test whether lateral parietal cortex actively represents the contents of memory. Using a large set of human face images, we first extracted

33 CFR 147.817 - Sir Douglas Morpeth Tension Leg Platform safety zone.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Sir Douglas Morpeth Tension Leg... HOMELAND SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.817 Sir Douglas Morpeth Tension Leg Platform safety zone. (a) Description. The Sir Douglas Morpeth Tension Leg Platform (Morpeth...

Single-leg squats can predict leg alignment in dancers performing ballet movements in "turnout".

PubMed

Hopper, Luke S; Sato, Nahoko; Weidemann, Andries L

2016-01-01

The physical assessments used in dance injury surveillance programs are often adapted from the sports and exercise domain. Bespoke physical assessments may be required for dance, particularly when ballet movements involve "turning out" or external rotation of the legs beyond that typically used in sports. This study evaluated the ability of the traditional single-leg squat to predict the leg alignment of dancers performing ballet movements with turnout. Three-dimensional kinematic data of dancers performing the single-leg squat and five ballet movements were recorded and analyzed. Reduction of the three-dimensional data into a one-dimensional variable incorporating the ankle, knee, and hip joint center positions provided the strongest predictive model between the single-leg squat and the ballet movements. The single-leg squat can predict leg alignment in dancers performing ballet movements, even in "turned out" postures. Clinicians should pay careful attention to observational positioning and rating criteria when assessing dancers performing the single-leg squat.

Dynamically Stable Legged Locomotion.

DTIC Science & Technology

1983-01-27

sweeps the leg during stance, and the third places the foot during flight and controls body attitude during stance. Each of the three methods elucidates...secondary strategy has been to examine systems with springy legs, so that the role of resonant oscillatory leg behavior might be better understood. ’ The ...body attitude : I lopping _leit: ’ The control system rcgulate:; hopping height by manlil)Lulating hopping energy. The leg is springy, so hopping is a

California Red-legged Frog - Stipulated Injunction

EPA Pesticide Factsheets

EPA will make effects determinations and initiate consultation with the U.S. Fish and Wildlife Service, regarding the potential effects of 66 pesticide active ingredient registrations on the California red-legged frog.

Muscle activity during leg strengthening exercise using free weights and elastic resistance: effects of ballistic vs controlled contractions.

PubMed

Jakobsen, Markus Due; Sundstrup, Emil; Andersen, Christoffer H; Aagaard, Per; Andersen, Lars L

2013-02-01

The present study's aim was to evaluate muscle activity during leg exercises using elastic vs. isoinertial resistance at different exertion and loading levels, respectively. Twenty-four women and eighteen men aged 26-67 years volunteered to participate in the experiment. Electromyographic (EMG) activity was recorded in nine muscles during a standardized forward lunge movement performed with dumbbells and elastic bands during (1) ballistic vs. controlled exertion, and (2) at low, medium and high loads (33%, 66% and 100% of 10 RM, respectively). The recorded EMG signals were normalized to MVC EMG. Knee joint angle was measured using electronic inclinometers. The following results were obtained. Loading intensity affected EMG amplitude in the order: lowactivity than slow controlled contractions, and for most muscles ballistic contractions with medium load showed similar EMG amplitude as controlled contractions with high load. At flexed knee joint positions with elastic resistance, quadriceps and gluteus EMG amplitude during medium-load ballistic contractions exceeded that recorded during high-load controlled contractions. Quadriceps and gluteus EMG amplitude increased at flexed knee positions. In contrast, hamstrings EMG amplitude remained constant throughout ROM during dumbbell lunge, but increased at more extended knee joint positions during lunges using elastic resistance. Based on these results, it can be concluded that lunges performed using medium-load ballistic muscle contractions may induce similar or even higher leg muscle activity than lunges using high-load slow-speed contractions. Consequently, lunges using elastic resistance appear to be equally effective in inducing high leg muscle activity as traditional lunges using isoinertial resistance. Copyright © 2012 Elsevier B.V. All rights reserved.

Activating social strategies: Face-to-face interaction in technology-mediated citizen science.

PubMed

Cappa, Francesco; Laut, Jeffrey; Nov, Oded; Giustiniano, Luca; Porfiri, Maurizio

2016-11-01

The use of crowds in research activities by public and private organizations is growing under different forms. Citizen science is a popular means of engaging the general public in research activities led by professional scientists. By involving a large number of amateur scientists, citizen science enables distributed data collection and analysis on a scale that would be otherwise difficult and costly to achieve. While advancements in information technology in the past few decades have fostered the growth of citizen science through online participation, several projects continue to fail due to limited participation. Such web-based projects may isolate the citizen scientists from the researchers. By adopting the perspective of social strategy, we investigate within a measure-manipulate-measure experiment if motivations to participate in a citizen science project can be positively influenced by a face-to-face interaction with the scientists leading the project. Such an interaction provides the participants with the possibility of asking questions on the spot and obtaining a detailed explanation of the citizen science project, its scientific merit, and environmental relevance. Social and cultural factors that moderate the effect brought about by face-to-face interactions on the motivations are also dissected and analyzed. Our findings provide an exploratory insight into a means for motivating crowds to participate in online environmental monitoring projects, also offering possible selection criteria of target audience. Copyright © 2016 Elsevier Ltd. All rights reserved.

How to find home backwards? Locomotion and inter-leg coordination during rearward walking of Cataglyphis fortis desert ants.

PubMed

Pfeffer, Sarah E; Wahl, Verena L; Wittlinger, Matthias

2016-07-15

For insects, flexibility in the performance of terrestrial locomotion is a vital part of facing the challenges of their often unpredictable environment. Arthropods such as scorpions and crustaceans can switch readily from forward to backward locomotion, but in insects this behaviour seems to be less common and, therefore, is only poorly understood. Here we present an example of spontaneous and persistent backward walking in Cataglyphis desert ants that allows us to investigate rearward locomotion within a natural context. When ants find a food item that is too large to be lifted up and to be carried in a normal forward-faced orientation, they will drag the load walking backwards to their home nest. A detailed examination of this behaviour reveals a surprising flexibility of the locomotor output. Compared with forward walks with regular tripod coordination, no main coordination pattern can be assigned to rearward walks. However, we often observed leg-pair-specific stepping patterns. The front legs frequently step with small stride lengths, while the middle and the hind legs are characterized by less numerous but larger strides. But still, these specializations show no rigidly fixed leg coupling, nor are they strictly embedded within a temporal context; therefore, they do not result in a repetitive coordination pattern. The individual legs act as separate units, most likely to better maintain stability during backward dragging. © 2016. Published by The Company of Biologists Ltd.

Sympathetic adaptations to one-legged training

NASA Technical Reports Server (NTRS)

Ray, C. A.

1999-01-01

The purpose of the present study was to determine the effect of leg exercise training on sympathetic nerve responses at rest and during dynamic exercise. Six men were trained by using high-intensity interval and prolonged continuous one-legged cycling 4 day/wk, 40 min/day, for 6 wk. Heart rate, mean arterial pressure (MAP), and muscle sympathetic nerve activity (MSNA; peroneal nerve) were measured during 3 min of upright dynamic one-legged knee extensions at 40 W before and after training. After training, peak oxygen uptake in the trained leg increased 19 +/- 2% (P < 0.01). At rest, heart rate decreased from 77 +/- 3 to 71 +/- 6 beats/min (P < 0.01) with no significant changes in MAP (91 +/- 7 to 91 +/- 11 mmHg) and MSNA (29 +/- 3 to 28 +/- 1 bursts/min). During exercise, both heart rate and MAP were lower after training (108 +/- 5 to 96 +/- 5 beats/min and 132 +/- 8 to 119 +/- 4 mmHg, respectively, during the third minute of exercise; P < 0.01). MSNA decreased similarly from rest during the first 2 min of exercise both before and after training. However, MSNA was significantly less during the third minute of exercise after training (32 +/- 2 to 22 +/- 3 bursts/min; P < 0.01). This training effect on MSNA remained when MSNA was expressed as bursts per 100 heartbeats. Responses to exercise in five untrained control subjects were not different at 0 and 6 wk. These results demonstrate that exercise training prolongs the decrease in MSNA during upright leg exercise and indicates that attenuation of MSNA to exercise reported with forearm training also occurs with leg training.

Mirror Self-Recognition beyond the Face

ERIC Educational Resources Information Center

Nielsen, Mark; Suddendorf, Thomas; Slaughter, Virginia

2006-01-01

Three studies (N=144) investigated how toddlers aged 18 and 24 months pass the surprise-mark test of self-recognition. In Study 1, toddlers were surreptitiously marked in successive conditions on their legs and faces with stickers visible only in a mirror. Rates of sticker touching did not differ significantly between conditions. In Study 2,…

33 CFR 147.821 - Brutus Tension Leg Platform safety zone.

Code of Federal Regulations, 2011 CFR

2011-07-01

... safety zone. 147.821 Section 147.821 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.821 Brutus Tension Leg Platform safety zone. (a) Description. The Brutus Tension Leg Platform (Brutus TLP), Green Canyon Block 158 (GC...

33 CFR 147.821 - Brutus Tension Leg Platform safety zone.

Code of Federal Regulations, 2012 CFR

2012-07-01

... safety zone. 147.821 Section 147.821 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.821 Brutus Tension Leg Platform safety zone. (a) Description. The Brutus Tension Leg Platform (Brutus TLP), Green Canyon Block 158 (GC...

33 CFR 147.821 - Brutus Tension Leg Platform safety zone.

Code of Federal Regulations, 2013 CFR

2013-07-01

... safety zone. 147.821 Section 147.821 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.821 Brutus Tension Leg Platform safety zone. (a) Description. The Brutus Tension Leg Platform (Brutus TLP), Green Canyon Block 158 (GC...

33 CFR 147.821 - Brutus Tension Leg Platform safety zone.

Code of Federal Regulations, 2014 CFR

2014-07-01

... safety zone. 147.821 Section 147.821 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.821 Brutus Tension Leg Platform safety zone. (a) Description. The Brutus Tension Leg Platform (Brutus TLP), Green Canyon Block 158 (GC...

33 CFR 147.821 - Brutus Tension Leg Platform safety zone.

Code of Federal Regulations, 2010 CFR

2010-07-01

... safety zone. 147.821 Section 147.821 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.821 Brutus Tension Leg Platform safety zone. (a) Description. The Brutus Tension Leg Platform (Brutus TLP), Green Canyon Block 158 (GC...

Single-leg squats can predict leg alignment in dancers performing ballet movements in “turnout”

PubMed Central

Hopper, Luke S; Sato, Nahoko; Weidemann, Andries L

2016-01-01

The physical assessments used in dance injury surveillance programs are often adapted from the sports and exercise domain. Bespoke physical assessments may be required for dance, particularly when ballet movements involve “turning out” or external rotation of the legs beyond that typically used in sports. This study evaluated the ability of the traditional single-leg squat to predict the leg alignment of dancers performing ballet movements with turnout. Three-dimensional kinematic data of dancers performing the single-leg squat and five ballet movements were recorded and analyzed. Reduction of the three-dimensional data into a one-dimensional variable incorporating the ankle, knee, and hip joint center positions provided the strongest predictive model between the single-leg squat and the ballet movements. The single-leg squat can predict leg alignment in dancers performing ballet movements, even in “turned out” postures. Clinicians should pay careful attention to observational positioning and rating criteria when assessing dancers performing the single-leg squat. PMID:27895518

Locomotor-Like Leg Movements Evoked by Rhythmic Arm Movements in Humans

PubMed Central

Sylos-Labini, Francesca; Ivanenko, Yuri P.; MacLellan, Michael J.; Cappellini, Germana; Poppele, Richard E.; Lacquaniti, Francesco

2014-01-01

Motion of the upper limbs is often coupled to that of the lower limbs in human bipedal locomotion. It is unclear, however, whether the functional coupling between upper and lower limbs is bi-directional, i.e. whether arm movements can affect the lumbosacral locomotor circuitry. Here we tested the effects of voluntary rhythmic arm movements on the lower limbs. Participants lay horizontally on their side with each leg suspended in an unloading exoskeleton. They moved their arms on an overhead treadmill as if they walked on their hands. Hand-walking in the antero-posterior direction resulted in significant locomotor-like movements of the legs in 58% of the participants. We further investigated quantitatively the responses in a subset of the responsive subjects. We found that the electromyographic (EMG) activity of proximal leg muscles was modulated over each cycle with a timing similar to that of normal locomotion. The frequency of kinematic and EMG oscillations in the legs typically differed from that of arm oscillations. The effect of hand-walking was direction specific since medio-lateral arm movements did not evoke appreciably leg air-stepping. Using externally imposed trunk movements and biomechanical modelling, we ruled out that the leg movements associated with hand-walking were mainly due to the mechanical transmission of trunk oscillations. EMG activity in hamstring muscles associated with hand-walking often continued when the leg movements were transiently blocked by the experimenter or following the termination of arm movements. The present results reinforce the idea that there exists a functional neural coupling between arm and legs. PMID:24608249

Selective attention modulates high-frequency activity in the face-processing network.

PubMed

Müsch, Kathrin; Hamamé, Carlos M; Perrone-Bertolotti, Marcela; Minotti, Lorella; Kahane, Philippe; Engel, Andreas K; Lachaux, Jean-Philippe; Schneider, Till R

2014-11-01

Face processing depends on the orchestrated activity of a large-scale neuronal network. Its activity can be modulated by attention as a function of task demands. However, it remains largely unknown whether voluntary, endogenous attention and reflexive, exogenous attention to facial expressions equally affect all regions of the face-processing network, and whether such effects primarily modify the strength of the neuronal response, the latency, the duration, or the spectral characteristics. We exploited the good temporal and spatial resolution of intracranial electroencephalography (iEEG) and recorded from depth electrodes to uncover the fast dynamics of emotional face processing. We investigated frequency-specific responses and event-related potentials (ERP) in the ventral occipito-temporal cortex (VOTC), ventral temporal cortex (VTC), anterior insula, orbitofrontal cortex (OFC), and amygdala when facial expressions were task-relevant or task-irrelevant. All investigated regions of interest (ROI) were clearly modulated by task demands and exhibited stronger changes in stimulus-induced gamma band activity (50-150 Hz) when facial expressions were task-relevant. Observed latencies demonstrate that the activation is temporally coordinated across the network, rather than serially proceeding along a processing hierarchy. Early and sustained responses to task-relevant faces in VOTC and VTC corroborate their role for the core system of face processing, but they also occurred in the anterior insula. Strong attentional modulation in the OFC and amygdala (300 msec) suggests that the extended system of the face-processing network is only recruited if the task demands active face processing. Contrary to our expectation, we rarely observed differences between fearful and neutral faces. Our results demonstrate that activity in the face-processing network is susceptible to the deployment of selective attention. Moreover, we show that endogenous attention operates along the whole

Frontal sled tests comparing rear and forward facing child restraints with 1-3 year old dummies.

PubMed

Sherwood, C P; Crandall, J R

2007-01-01

Although most countries recommend transitioning children from rear facing (RF) to forward facing (FF) child restraints at one year of age, Swedish data suggests that RF restraints are more effective. The objective of this study was to compare RF and FF orientations in frontal sled tests. Four dummies (CRABI 12 mo, Q1.5, Hybrid III 3 yr, and Q3) were used to represent children from 1 to 3 years of age. Restraint systems tested included both 1) LATCH and 2) rigid ISOFIX with support leg designs. Rear facing restraints with support legs provided the best results for all injury measures, while RF restraints in general provided the lowest chest displacements and neck loads.

Restless Legs Syndrome

MedlinePlus

... Legs Syndrome Condition Restless Legs Syndrome Share Print Table of Contents1. Overview2. Symptoms3. Diagnosis4. Treatment5. Questions Overview ... twitch when you try and sleep (also called periodic limb movements of sleep or PLMS). Diagnosis How ...

[Contact eczema in patients with leg ulcers].

PubMed

Degreef, H; Dooms-Goossens, A; Gladys, K

1986-01-01

Patients with leg ulcers or varicose eczema suffer much more often from contact eczema due to the local application of pharmaceutical preparations than patients suffering from other dermatological problems (even those of eczematous origin). This contact allergy may concern not only the active ingredient but also the excipient, the preservative, or even the perfume. In all cases of leg ulcers, of varicose eczema, but also of badly healed ulcers, epicutaneous tests should be carried out with all the components of the pharmaceutical preparations concerned. Moreover, the pharmaceutical industry really must perfect non-allergenic preparations.

Frontoparietal Activation Distinguishes Face and Space from Artifact Concepts

PubMed Central

Chen, Chi-Hua; Zeki, Semir

2012-01-01

Empirical and theoretical studies suggest that human knowledge is partly based on innate concepts that are experience-independent. We can, therefore, consider concepts underlying our knowledge as being broadly divided into inherited and acquired ones. Using fMRI, we studied the brain reaction in 20 subjects to violation of face, space (inherited), and artifact (acquired) concepts by presenting them with deformed faces, impossible figures (i.e., impossible chairs), and deformed planes, respectively, as well as their normal counterparts. Violation of the inherited concepts of face and space led to significant activation in frontoparietal cortex, whereas artifacts did not, thus distinguishing neurologically between the two categories. Participants were further exposed to these deformities daily for 1 month to test the supposition that inherited concepts are not modifiable, hence that prolonged exposure would not change the brain circuits that are engaged when viewing them. Consistent with this supposition, our results showed no significant change in activation for both categories, suggesting that such concepts are stable at the neural level at least within a time frame of 1 month. Finally, we investigated the regions of the brain that are critical for object representation. Our results show distinct and overlapping areas in the ventral visual cortex for all three categories, with faces activating the ventral visual cortex inferiorly, especially centered on right fusiform gyrus, and chairs and planes activating more diffuse regions, overlapping with the superior part of face region and mainly located in middle occipital cortex and parietal areas. PMID:21254806

Facing two faces: Defense activation varies as a function of personal relevance.

PubMed

Bublatzky, Florian; Alpers, Georg W

2017-04-01

It can be unsettling to be watched by a group of people, and when they express anger or hostility, this can prime defensive behavior. In contrast, when others smile at us, this may be comforting. This study tested to which degree the impact of facial expressions (happy, neutral, and angry) varies with the personal relevance of a social situation. Modelling a triadic situation, two faces looked either directly at the participant, faced each other, or they were back to back. Results confirmed that this variation constitutes a gradient of personal relevance (directed frontally > towards > away), as reflected by corresponding defensive startle modulation and autonomic nervous system activity. This gradient was particularly pronounced for angry faces and it was steeper in participants with higher levels of social anxiety. Thus, sender-recipient constellations modulate the processing of facial emotions in favor of adequate behavioral responding (e.g., avoidance) in group settings. Copyright © 2017 Elsevier B.V. All rights reserved.

Face washing promotion for preventing active trachoma

PubMed Central

Ejere, Henry OD; Alhassan, Mahmoud B; Rabiu, Mansur

2015-01-01

Background Trachoma remains a major cause of avoidable blindness among underprivileged populations in many developing countries. It is estimated that about 146 million people have active trachoma and nearly six million people are blind due to complications associated with repeat infections. Objectives The objective of this review was to assess the effects of face washing promotion for the prevention of active trachoma in endemic communities. Search methods We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2015, Issue 1), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to January 2015), EMBASE (January 1980 to January 2015), PubMed (January 1948 to January 2015), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to January 2015), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) (accessed 10 January 2014), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 26 January 2015. To identify further relevant trials we checked the reference lists of the included trials. Also, we used the Science Citation Index to search for references to publications that cited the trials included in the review. We contacted investigators and experts in the field to identify additional trials. Selection criteria We included randomized controlled trials (RCTs) or quasi-RCTs that compared face washing with no treatment or face washing combined with antibiotics against antibiotics alone. Trial participants were residents of endemic trachoma communities. Data collection and analysis Two review authors independently extracted data and assessed trial quality. We contacted trial

Shin-splints: common exercise-related syndromes affecting the lower leg.

PubMed

Williamson, B L; Arthur, C H C

2014-01-01

Lower leg pain is a common complaint of athletically active individuals, often limiting physical activities. As such, the group of lower leg conditions related to athletic pursuits and physical exercise confer considerable operational implications for the military. Whilst acute injuries to the lower limb are commonly encountered and are clearly of significance, this article focuses instead on chronic conditions related to physical activity. These include insults to bone such as stress fractures and medial tibial stress syndrome, and those related to the soft tissues such as chronic exertional compartment syndrome. In this article we will examine the presentation and management of these conditions.

Soy undecapeptide induces Drosophila hind leg grooming via dopamine receptor.

PubMed

Karim, M Rezaul; Yanagawa, Aya; Ohinata, Kousaku

2018-05-15

β-Conglycinin α subunit (323-333) [βCGα(323-333)] is an exogenous neuromodulating undecapeptide found from enzymatic digest of β-conglycinin, a soy major storage protein by mice behavior tests. We investigated effect of βCGα(323-333) on Drosophila behavior. Oral administration of βCGα(323-333) in Drosophila increased hind leg grooming, which may act through specific sets of neurons. It was reported that dopamine receptor (DopR) meditates hind leg grooming, and we tested involvement of DopR in βCGα(323-333)-induced hind leg grooming by using DopR knockout flies. In the wild type but not in the DopR-knockout flies, βCGα(323-333) increased hind leg grooming. These results suggest that βCGα(323-333) induces hind leg grooming via activating the DopR. This is the first report showing that exogenously administered peptide changes fly behaviors. Copyright © 2018 Elsevier Inc. All rights reserved.

Increasing trunk flexion transforms human leg function into that of birds despite different leg morphology.

PubMed

Aminiaghdam, Soran; Rode, Christian; Müller, Roy; Blickhan, Reinhard

2017-02-01

Pronograde trunk orientation in small birds causes prominent intra-limb asymmetries in the leg function. As yet, it is not clear whether these asymmetries induced by the trunk reflect general constraints on the leg function regardless of the specific leg architecture or size of the species. To address this, we instructed 12 human volunteers to walk at a self-selected velocity with four postures: regular erect, or with 30 deg, 50 deg and maximal trunk flexion. In addition, we simulated the axial leg force (along the line connecting hip and centre of pressure) using two simple models: spring and damper in series, and parallel spring and damper. As trunk flexion increases, lower limb joints become more flexed during stance. Similar to birds, the associated posterior shift of the hip relative to the centre of mass leads to a shorter leg at toe-off than at touchdown, and to a flatter angle of attack and a steeper leg angle at toe-off. Furthermore, walking with maximal trunk flexion induces right-skewed vertical and horizontal ground reaction force profiles comparable to those in birds. Interestingly, the spring and damper in series model provides a superior prediction of the axial leg force across trunk-flexed gaits compared with the parallel spring and damper model; in regular erect gait, the damper does not substantially improve the reproduction of the human axial leg force. In conclusion, mimicking the pronograde locomotion of birds by bending the trunk forward in humans causes a leg function similar to that of birds despite the different morphology of the segmented legs. © 2017. Published by The Company of Biologists Ltd.

Steerable Hopping Six-Legged Robot

NASA Technical Reports Server (NTRS)

Younse, Paulo; Aghazarian, Hrand

2010-01-01

The figure depicts selected aspects of a six-legged robot that moves by hopping and that can be steered in the sense that it can be launched into a hop in a controllable direction. This is a prototype of hopping robots being developed for use in scientific exploration of rough terrain on remote planets that have surface gravitation less than that of Earth. Hopping robots could also be used on Earth, albeit at diminished hopping distances associated with the greater Earth gravitation. The upper end of each leg is connected through two universal joints to an upper and a lower hexagonal frame, such that the tilt of the leg depends on the relative position of the two frames. Two non-back-driveable worm-gear motor drives are used to control the relative position of the two frames along two axes 120 apart, thereby controlling the common tilt of all six legs and thereby, further, controlling the direction of hopping. Each leg includes an upper and a lower aluminum frame segment with a joint between them. A fiberglass spring, connected via hinges to both segments, is used to store hopping energy prior to launch into a hop and to cushion the landing at the end of the hop. A cable for loading the spring is run into each leg through the center of the universal joints and then down along the center lines of the segments to the lower end of the leg. A central spool actuated by a motor with a harmonic drive and an electromagnetic clutch winds in all six cables to compress all six springs (thereby also flexing all six legs) simultaneously. To ensure that all the legs push off and land in the same direction, timing- belt pulley drives are attached to the leg segments, restricting the flexing and extension of all six legs to a common linear motion. In preparation for a hop, the spool can be driven to load the spring legs by an amount corresponding to a desired hop distance within range. The amount of compression can be computed from the reading of a shaft-angle encoder that

Similarities in neural activations of face and Chinese character discrimination.

PubMed

Liu, Jiangang; Tian, Jie; Li, Jun; Gong, Qiyong; Lee, Kang

2009-02-18

This study compared Chinese participants' visual discrimination of Chinese faces with that of Chinese characters, which are highly similar to faces on a variety of dimensions. Both Chinese faces and characters activated the bilateral middle fusiform with high levels of correlations. These findings suggest that although the expertise systems for faces and written symbols are known to be anatomically differentiated at the later stages of processing to serve face processing or written-symbol-specific processing purposes, they may share similar neural structures in the ventral occipitotemporal cortex at the stages of visual processing.

Sandwich masking eliminates both visual awareness of faces and face-specific brain activity through a feedforward mechanism.

PubMed

Harris, Joseph A; Wu, Chien-Te; Woldorff, Marty G

2011-06-07

It is generally agreed that considerable amounts of low-level sensory processing of visual stimuli can occur without conscious awareness. On the other hand, the degree of higher level visual processing that occurs in the absence of awareness is as yet unclear. Here, event-related potential (ERP) measures of brain activity were recorded during a sandwich-masking paradigm, a commonly used approach for attenuating conscious awareness of visual stimulus content. In particular, the present study used a combination of ERP activation contrasts to track both early sensory-processing ERP components and face-specific N170 ERP activations, in trials with versus without awareness. The electrophysiological measures revealed that the sandwich masking abolished the early face-specific N170 neural response (peaking at ~170 ms post-stimulus), an effect that paralleled the abolition of awareness of face versus non-face image content. Furthermore, however, the masking appeared to render a strong attenuation of earlier feedforward visual sensory-processing signals. This early attenuation presumably resulted in insufficient information being fed into the higher level visual system pathways specific to object category processing, thus leading to unawareness of the visual object content. These results support a coupling of visual awareness and neural indices of face processing, while also demonstrating an early low-level mechanism of interference in sandwich masking.

A randomised clinical trial of the efficacy of drop squats or leg extension/leg curl exercises to treat clinically diagnosed jumper's knee in athletes: pilot study

PubMed Central

Cannell, L; Taunton, J; Clement, D; Smith, C; Khan, K

2001-01-01

Objectives—To compare the therapeutic effect of two different exercise protocols in athletes with jumper's knee. Methods—Randomised clinical trial comparing a 12 week programme of either drop squat exercises or leg extension/leg curl exercises. Measurement was performed at baseline and after six and 12 weeks. Primary outcome measures were pain (visual analogue scale 1–10) and return to sport. Secondary outcome measures included quadriceps and hamstring moment of force using a Cybex II isokinetic dynamometer at 30°/second. Differences in pain response between the drop squat and leg extension/curl treatment groups were assessed by 2 (group) x 3 (time) analysis of variance. Two by two contingency tables were used to test differences in rates of return to sport. Analysis of variance (2 (injured versus non-injured leg) x 2 (group) x 3 (time)) was also used to determine differences for secondary outcome measures. Results—Over the 12 week intervention, pain diminished by 2.3 points (36%) in the leg extension/curl group and 3.2 points (57%) in the squat group. There was a significant main effect of both exercise protocols on pain (p<0.01) with no interaction effect. Nine of 10 subjects in the drop squat group returned to sporting activity by 12 weeks, but five of those subjects still had low level pain. Six of nine of the leg extension/curl group returned to sporting activity by 12 weeks and four patients had low level pain. There was no significant difference between groups in numbers returning to sporting activity. There were no differences in the change in quadriceps or hamstring muscle moment of force between groups. Conclusions—Progressive drop squats and leg extension/curl exercises can reduce the pain of jumper's knee in a 12 week period and permit a high proportion of patients to return to sport. Not all patients, however, return to sport by that time. Key Words: knee; patellar tendon; tendinopathy; tendinosis; eccentric strengthening; strength training

Prevalence of skin problems and leg ulceration in a sample of young injecting drug users.

PubMed

Coull, Alison F; Atherton, Iain; Taylor, Avril; Watterson, Andrew E

2014-08-13

Drug users suffer harm from the injecting process, and clinical services are reporting increasing numbers presenting with skin-related problems such as abscesses and leg ulcers. Skin breakdown can lead to long-term health problems and increased service costs and is often the first indication of serious systemic ill health. The extent of skin problems in injecting drug users has not previously been quantified empirically, and there is a dearth of robust topical literature. Where skin problems have been reported, this is often without clear definition and generic terms such as 'soft tissue infection' are used which lack specificity. The aim of this study was to identify the range and extent of skin problems including leg ulceration in a sample of injecting drug users. Definitions of skin problems were developed and applied to descriptions from drug users to improve rigour. Data were collected in needle exchanges and methadone clinics across Glasgow, Scotland, from both current and former drug injectors using face-to-face interviews. Two hundred participants were recruited, of which 74% (n = 148) were males and 26% (n = 52) were females. The age range was 21-44 years (mean 35 years). Just under two thirds (64%, n = 127) were currently injecting or had injected within the last 6 months, and 36% (n = 73) had previously injected and had not injected for more than 6 months.Sixty per cent (n = 120) of the sample had experienced a skin problem, and the majority reported more than one problem. Most common were abscesses, lumps, track marks and leg ulcers. Fifteen per cent (n = 30) of all participants reported having had a leg ulcer. This is an original empirical study which demonstrated unique findings of a high prevalence of skin disease (60%) and surprisingly high rates of leg ulceration (15%). Skin disease in injecting drug users is clearly widespread. Leg ulceration in particular is a chronic recurring condition that is costly to treat and has

Leg Injuries and Disorders

MedlinePlus

... are important for motion and standing. Playing sports, running, falling, or having an accident can damage your legs. Common leg injuries include sprains and strains, joint dislocations, and fractures. ...

Terrestrial activity and conservation of adult California red-legged frogs Rana aurora draytonii in coastal forests and grasslands

USGS Publications Warehouse

Bulger, J.B.; Scott, N.J.; Seymour, R.B.

2003-01-01

The federally threatened California red-legged frog Rana aurora draytonii occupies both aquatic and terrestrial habitats in its adult life stage. The terrestrial activities of this species are not well known and require documentation to assist in the development of appropriate levels of protection under the US Endangered Species Act. We studied the terrestrial activities of radio-tagged red-legged frogs (n = 8-26) inhabiting a coastal watershed in Santa Cruz County, California, during 1997-1998. In particular, we investigated (1) the use of terrestrial habitats by non-migrating adults in relation to season, breeding chronology, and precipitation, and (2) adult migration behavior, including seasonal timing, duration, distances traveled, and the use of corridors. Non-migrating red-legged frogs occupied terrestrial habitats briefly (median = 4-6 days) following infrequent summer rains, but resided nearly continuously on land (median = 20-30 days) from the onset of the winter wet-season until breeding activities commenced 1-2 months later. All of the non-migrating frogs remained within 130 m of their aquatic site of residence (median <25 m). Intervals spent on land were again brief during mid/late winter (median = 1-4 days), despite frequent and copious rainfall. Adult migration to and from breeding sites occurred from late October through mid-May (wet season). We monitored 25 migration events between aquatic sites that were 200-2800 m apart. Short distance movements ( <300 m) were completed in 1-3 days, longer movements required up to 2 months. Most migrating frogs moved overland in approximately straight lines to target sites without apparent regard to vegetation type or topography. Riparian corridors were neither essential nor preferred as migration routes. Frogs traveling overland occurred in upland habitats as far as 500 m from water. Approximately 11-22% of the adult population was estimated to migrate to and from breeding sites annually, whereas the bulk of the

Endogenous pro-thrombotic biomarkers from the arm and leg may not have the same value.

PubMed

Lattimer, Christopher R; Kalodiki, Evi; Geroulakos, George; Hoppensteadt, Debra; Fareed, Jawed

2016-05-01

Assessments of endogenous pro-thrombotic biomarkers are performed invariably on arm blood. However, the commonest site for thrombosis is in the leg. A leg blood sample may reflect local pro-thrombotic processes more accurately than systemic arm blood. The aim was to determine whether pro-thrombotic biomarkers from standard venous arm samples differed significantly from leg samples. Concurrent blood samples were taken from an ankle/lower calf varicose vein and an ante-cubital vein in 24 patients awaiting laser treatment as well as age approximated and sex matched healthy controls without venous disease. The following assays were performed: thrombin-antithrombin (ng/ml), antithrombin (%) activity, microparticles (nM), fibrinogen (mg/dl), prothrombin fragment 1.2 (F1.2) (pM) and P-selectin (ng/ml). Expressed as median (inter-quartile range). Significant arm/leg differences were observed in thrombin-antithrombin, antithrombin, prothrombin fragment 1.2 and P-selectin. The legs of patients had significantly reduced antithrombin activity and P-selectin concentrations compared to their arms (leg: 101 (90-108) versus arm: 112 (99-126), P = 0.001 and leg: 42 (26-52) versus 45 (27-52), P = 0.044, respectively). Control leg samples had significantly increased thrombin-antithrombin and P-selectin compared to control arm samples (leg: 2.1 (0.9-3.2) versus arm: 0.8 (0.5-1.7), P = 0.015 and leg: 36 (24-50) versus arm: 30 (23-41), P = 0.007, respectively). However, the control legs had significantly reduced F1.2 (leg: 265 (230-333) versus arm: 299 (236-361), P = 0.028). No significant arm/leg differences were detected in the microparticle or fibrinogen levels. These findings indicate that venous arm blood is significantly different from venous leg blood in four out of six biomarkers studied. Recognition of local venous leg sampling as a site for investigation may unravel why the leg has a greater predisposition to thrombosis and lead the way towards an arm/leg

Restless legs syndrome and pregnancy or delivery complications in China: a representative survey.

PubMed

Liu, Gangqiong; Li, Ling; Zhang, Jinying; Xue, Rui; Zhao, Xiaoyan; Zhu, Kui; Wang, Yunzhe; Xiao, Lili; Shangguan, Jiahong

2016-01-01

To perform a detailed epidemiological study of Chinese women and the relationship between restless legs syndrome (RLS) in pregnancy and any associated complications during delivery. A total of 3874 pregnant women (18-40 years) who had delivered babies at The First Affiliated Hospital of Zhengzhou University from May 2011 to May 2014 were enrolled in the study. Using a face-to-face interview questionnaire, data were collected pertaining to RLS incidence in pregnancy and any associated complications during delivery. The relationship between RLS frequency and pregnancy or delivery complications was further investigated. Among 12.3% of the eligible participants, RLS prevalence occurred at least weekly. Older pregnant women were more likely to suffer from RLS. Individuals who experienced RLS at least weekly reported a statistically higher frequency of excessive daytime sleepiness and an increased prevalence of hypertension, cardiovascular disease, and preeclampsia compared with those without RLS. The study revealed that RLS was frequent in Chinese pregnant women, especially in those with pregnancy or delivery complications such as hypertension, cardiovascular disease, and preeclampsia. Restless legs syndrome was also associated with excessive daytime sleepiness. Copyright © 2015 Elsevier B.V. All rights reserved.

Athletes' leg pains.

PubMed Central

Orava, S.; Puranen, J.

1979-01-01

The frequency and nature of exertion pains of the leg in athletes were studied in 2,750 cases of overuse injuries treated at the Sports Clinic of the Deaconess Institute of Oulu, Finland, during the years 1972-1977. 465 cases of exertion pain (18%) were located in the shin. The medial tibial syndrome was the most common overuse injury among these athletes, comprising 9.5% of all exertion injuries and 60% of the leg exertion pains. Together with stress fracture of the tibia, the second most common exertion pain of the leg, it accounted for 75% of the total leg pains. There are certain difficulties in differentiating between the medial tibial syndrome and stress fracture of the tibia. They both occur at the same site with similar symptoms. Radiological examination and isotope scanning are needed. The medial tibial syndrome is an overuse injury at the medial tibial border caused by running exercises. The pain is elicited by exertional ischaemia. The pathogenesis is explained by increased pressure in the fascial compartment of the deep flexor muscles due to prolonged exercise. Similar chronic ischaemic pains from exercise are also found in other fascial compartments of the leg, especially in the anterior compartment. The only treatment needed for stress fractures is rest from training. Fascial compartment pains also usually subside. If chronic fascial syndromes prevent training, fasciotomy is recommended as a reliable method to restore the athlete to normal training without pains. PMID:486888

Neuromuscular Evaluation With Single-Leg Squat Test at 6 Months After Anterior Cruciate Ligament Reconstruction

PubMed Central

Hall, Michael P.; Paik, Ronald S.; Ware, Anthony J.; Mohr, Karen J.; Limpisvasti, Orr

2015-01-01

Background: Criteria for return to unrestricted activity after anterior cruciate ligament (ACL) reconstruction varies, with some using time after surgery as the sole criterion—most often at 6 months. Patients may have residual neuromuscular deficits, which may increase the risk of ACL injury. A single-leg squat test (SLST) can dynamically assess for many of these deficits prior to return to unrestricted activity. Hypothesis: A significant number of patients will continue to exhibit neuromuscular deficits with SLST at 6 months after ACL reconstruction. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Patients using a standardized accelerated rehabilitation protocol at their 6-month follow-up after primary ACL reconstruction were enrolled. Evaluation included bilateral SLST, single-leg hop distance, hip abduction strength, and the subjective International Knee Documentation Committee (IKDC) score. Results: Thirty-three patients were enrolled. Poor performance of the operative leg SLST was found in 15 of 33 patients (45%). Of those 15 patients, 7 (45%) had concomitant poor performance of the nonoperative leg compared with 2 of 18 patients (11%) in those who demonstrated good performance in the operative leg. The poor performers were significantly older (33.6 years) than the good performers (24.2 years) (P = .007). Those with poor performance demonstrated decreased hip abduction strength (17.6 kg operative leg vs 20.5 kg nonoperative leg) (P = .024), decreased single-leg hop distance (83.3 cm operative leg vs 112.3 cm nonoperative leg) (P = .036), and lower IKDC scores (67.9 vs 82.3) (P = .001). Conclusion: Nearly half of patients demonstrated persistent neuromuscular deficits on SLST at 6 months, which is when many patients return to unrestricted activity. Those with poor performance were of a significantly older age, decreased hip abduction strength, decreased single-leg hop distance, and lower IKDC subjective scores. Clinical Relevance: The SLST

A causal relationship between face-patch activity and face-detection behavior.

PubMed

Sadagopan, Srivatsun; Zarco, Wilbert; Freiwald, Winrich A

2017-04-04

The primate brain contains distinct areas densely populated by face-selective neurons. One of these, face-patch ML, contains neurons selective for contrast relationships between face parts. Such contrast-relationships can serve as powerful heuristics for face detection. However, it is unknown whether neurons with such selectivity actually support face-detection behavior. Here, we devised a naturalistic face-detection task and combined it with fMRI-guided pharmacological inactivation of ML to test whether ML is of critical importance for real-world face detection. We found that inactivation of ML impairs face detection. The effect was anatomically specific, as inactivation of areas outside ML did not affect face detection, and it was categorically specific, as inactivation of ML impaired face detection while sparing body and object detection. These results establish that ML function is crucial for detection of faces in natural scenes, performing a critical first step on which other face processing operations can build.

Intramuscular pressures beneath elastic and inelastic leggings

NASA Technical Reports Server (NTRS)

Murthy, G.; Ballard, R. E.; Breit, G. A.; Watenpaugh, D. E.; Hargens, A. R.

1994-01-01

Leg compression devices have been used extensively by patients to combat chronic venous insufficiency and by astronauts to counteract orthostatic intolerance following spaceflight. However, the effects of elastic and inelastic leggings on the calf muscle pump have not been compared. The purpose of this study was to compare in normal subjects the effects of elastic and inelastic compression on leg intramuscular pressure (IMP), an objective index of calf muscle pump function. IMP in soleus and tibialis anterior muscles was measured with transducer-tipped catheters. Surface compression between each legging and the skin was recorded with an air bladder. Subjects were studied under three conditions: (1) control (no legging), (2) elastic legging, and (3) inelastic legging. Pressure data were recorded for each condition during recumbency, sitting, standing, walking, and running. Elastic leggings applied significantly greater surface compression during recumbency (20 +/- 1 mm Hg, mean +/- SE) than inelastic leggings (13 +/- 2 mm Hg). During recumbency, elastic leggings produced significantly higher soleus IMP of 25 +/- 1 mm Hg and tibialis anterior IMP of 28 +/- 1 mm Hg compared to 17 +/- 1 mm Hg and 20 +/- 2 mm Hg, respectively, generated by inelastic leggings and 8 +/- 1 mm Hg and 11 +/- 1 mm Hg, respectively, without leggings. During sitting, walking, and running, however, peak IMPs generated in the muscular compartments by elastic and inelastic leggings were similar. Our results suggest that elastic leg compression applied over a long period in the recumbent posture may impede microcirculation and jeopardize tissue viability.(ABSTRACT TRUNCATED AT 250 WORDS).

Neural activation to emotional faces in adolescents with autism spectrum disorders.

PubMed

Weng, Shih-Jen; Carrasco, Melisa; Swartz, Johnna R; Wiggins, Jillian Lee; Kurapati, Nikhil; Liberzon, Israel; Risi, Susan; Lord, Catherine; Monk, Christopher S

2011-03-01

Autism spectrum disorders (ASD) involve a core deficit in social functioning and impairments in the ability to recognize face emotions. In an emotional faces task designed to constrain group differences in attention, the present study used functional MRI to characterize activation in the amygdala, ventral prefrontal cortex (vPFC), and striatum, three structures involved in socio-emotional processing in adolescents with ASD. Twenty-two adolescents with ASD and 20 healthy adolescents viewed facial expressions (happy, fearful, sad and neutral) that were briefly presented (250 ms) during functional MRI acquisition. To monitor attention, subjects pressed a button to identify the gender of each face. The ASD group showed greater activation to the faces relative to the control group in the amygdala, vPFC and striatum. Follow-up analyses indicated that the ASD relative to control group showed greater activation in the amygdala, vPFC and striatum (p < .05 small volume corrected), particularly to sad faces. Moreover, in the ASD group, there was a negative correlation between developmental variables (age and pubertal status) and mean activation from the whole bilateral amygdala; younger adolescents showed greater activation than older adolescents. There were no group differences in accuracy or reaction time in the gender identification task. When group differences in attention to facial expressions were limited, adolescents with ASD showed greater activation in structures involved in socio-emotional processing. © 2010 The Authors. Journal of Child Psychology and Psychiatry © 2010 Association for Child and Adolescent Mental Health.

[Restless Legs Syndrome : A Threat to the quality of life].

PubMed

Castaño-Cárcamo, Mauricio; Escobar-Cordoba, Franklin; Rey de Castro, Jorge

2014-01-01

Restless legs syndrome is a disorder associated with the imperative need to move the legs, starting at different times of day and it gets worse at night, relieved by activity, affecting the quality of life and sleep who sufferers it. Despite being a common disorder at any age, in adults with a prevalence of up to 10%, is not diagnosed by doctors and first level specialists that is why diagnostic and therapeutic interventions get delayed contributing to the perpetuation of symptoms and worsening quality of life. Since its diagnosis is purely clinical, getting familiar with this disorder is essential to ensure proper focus and thus rule out other diseases commonly confused with this one. Restless legs syndrome has a multi-factorial etiology that ranges from a genetic and hereditary, which are called primary restless legs syndrome, to its association with multiple pathologies, known as secondary restless legs syndrome. As for its management, drug therapy and non-drug therapy is aimed at symptom control, as its cure is not possible, although occasionally the condition can refer to later repeat in months or years.

Functional aspects of cross-legged sitting with special attention to piriformis muscles and sacroiliac joints.

PubMed

Snijders, Chris J; Hermans, Paul F G; Kleinrensink, Gerrit Jan

2006-02-01

Transversely oriented pelvic muscles such as the internal abdominal oblique, transversus abdominis, piriformis and pelvic floor muscles may contribute to sacroiliac joint stability by pressing the sacrum between the hipbones. Surface electromyographic measurements showed that leg crossing lowers the activity of the internal oblique abdominal muscle significantly. This suggests that leg crossing is a substitute for abdominal muscle activity. No previous studies addressed piriformis muscle and related pelvic structures in cross-legged sitting. Angles of pelvis and femur were measured in healthy subjects in standing, normal sitting and cross-legged sitting, and were used to simulate these postures on embalmed pelvises and measure piriformis muscle elongation. Deformations of pelvic ring and iliolumbar ligament caused by piriformis muscle force were measured on embalmed pelvises. Cross-legged sitting resulted in a relative elongation of the piriformis muscle of 11.7% compared to normal sitting and even 21.4% compared to standing. Application of piriformis muscle force resulted in inward deformation of the pelvic ring and compression of the sacroiliac joints and the dorsal side of the pubic symphysis. Cross-legged sitting is common. We believe that it contributes to sacroiliac joint stability. This study demonstrates the influence of the piriformis muscle on sacroiliac joint compression. The elongation of the piriformis muscle bilaterally by crossing the legs may be functional in the build-up of active or passive tension between sacrum and femur.

High day-to-day reliability in lower leg volume measured by water displacement.

PubMed

Pasley, Jeffrey D; O'Connor, Patrick J

2008-07-01

The day-to-day reliability of lower leg volume is poorly documented. This investigation determined the day-to-day reliability of lower leg volume (soleus and gastrocnemius) measured using water displacement. Thirty young adults (15 men and 15 women) had their right lower leg volume measured by water displacement on five separate occasions. The participants performed normal activities of daily living and were measured at the same time of day after being seated for 30 min. The results revealed a high day-to-day reliability for lower leg volume. The mean percentage change in lower leg volume across days compared to day 1 ranged between 0 and 0.37%. The mean within subjects coefficient of variation in lower leg volume was 0.72% and the coefficient of variation for the entire sample across days ranged from 5.66 to 6.32%. A two way mixed model intraclass correlation (30 subjects x 5 days) showed that the lower leg volume measurement was highly reliable (ICC = 0.972). Foot and total lower leg volumes showed similarly high reliability. Water displacement offers a cost effective and reliable solution for the measurement of lower leg edema across days.

Brain activation while forming memories of fearful and neutral faces in women and men.

PubMed

Fischer, Håkan; Sandblom, Johan; Nyberg, Lars; Herlitz, Agneta; Bäckman, Lars

2007-11-01

Event-related functional MRI (fMRI) was used to assess brain activity during encoding of fearful and neutral faces in 12 women and 12 men. In a subsequent memory analysis, the authors separated successful from unsuccessful encoding of both types of faces, based on whether they were remembered or forgotten in a later recognition memory test. Overall, women and men recruited overlapping neural circuitries. Both sexes activated right-sided medial-temporal regions during successful encoding of fearful faces. Successful encoding of neutral faces was associated with left-sided lateral prefrontal and right-sided superior frontal activation in both sexes. In women, relatively greater encoding related activity for neutral faces was seen in the superior parietal and parahippocampal cortices. By contrast, men activated the left and right superior/middle frontal cortex more than women during successful encoding of the same neutral faces. These findings suggest that women and men use similar neural networks to encode facial information, with only subtle sex differences observed for neutral faces.

Quantitative rest activity in ambulatory monitoring as a physiological marker of restless legs syndrome: a controlled study.

PubMed

Tuisku, Katinka; Holi, Matti Mikael; Wahlbeck, Kristian; Ahlgren, Aulikki Johanna; Lauerma, Hannu

2003-04-01

An objective marker of restless legs syndrome (RLS) is needed for developing diagnostic tools and monitoring symptoms. Actometric ambulatory monitoring of 15 RLS patients and 15 healthy controls was undertaken in order to differentiate between RLS-related motor symptoms and normal motor activity. Nocturnal lower-limb activity per minute differentiated and discriminated between groups with no overlap, whereas the periodic limb movement index and the controlled rest activity during sitting showed less discriminative power. The naturalistic recording of nocturnal activity by actometry may prove useful for assessing the severity of RLS and for finding an objective marker to support the diagnosis of RLS. Copyright 2002 Movement Disorder Society

Net joint moments and muscle activation in barbell squats without and with restricted anterior leg rotation.

PubMed

Chiu, Loren Z F; vonGaza, Gabriella L; Jean, Liane M Y

2017-01-01

Muscle utilisation in squat exercise depends on technique. The purpose of this study was to compare net joint moments (NJMs) and muscle activation during squats without and with restricted leg dorsiflexion. Experienced men (n = 5) and women (n = 4) performed full squats at 80% one repetition maximum. 3D motion analysis, force platform and (EMG) data were collected. Restricting anterior leg rotation reduced anterior leg (P = 0.001) and posterior thigh (P < 0.001) rotations, resulting in a smaller knee flexion range of motion (P < 0.001). At maximum squat depth, ankle plantar flexor (P < 0.001) and knee extensor (P < 0.001) NJM were higher in unrestricted squats. Hip extensor NJM (P = 0.14) was not different between squat types at maximum squat depth. Vastus lateralis (P > 0.05), vastus medialis (P > 0.05) and rectus femoris (P > 0.05) EMG were not different between squat types. Unrestricted squats have higher ankle plantar flexor and knee extensor NJM than previously reported from jumping and landing. However, ankle plantar flexor and knee extensor NJM are lower in restricted squats than previous studies of jumping and landing. The high NJM in unrestricted squat exercise performed through a full range of motion suggests this squat type would be more effective to stimulate adaptations in the lower extremity musculature than restricted squats.

Leg Injuries and Disorders - Multiple Languages

MedlinePlus

... sharing features on this page, please enable JavaScript. Arabic (العربية) Chinese, Simplified (Mandarin dialect) (简体中文) Chinese, Traditional ( ... HealthReach resources will open in a new window. Arabic (العربية) Expand Section Active Leg Range of Motion - ...

Static balance according to hip joint angle of unsupported leg during one-leg standing.

PubMed

Cha, Ju-Hyung; Kim, Jang-Joon; Ye, Jae-Gwan; Lee, Seul-Ji; Hong, Jeong-Mi; Choi, Hyun-Kyu; Choi, Ho-Suk; Shin, Won-Seob

2017-05-01

[Purpose] This study aimed to determine static balance according to hip joint angle of the unsupported leg during one-leg standing. [Subjects and Methods] Subjects included 45 healthy adult males and females in their 20s. During one-leg standing on the non-dominant leg, the position of the unsupported leg was classified according to hip joint angles of point angle was class. Static balance was then measured using a force plate with eyes open and closed. The total length, sway velocity, maximum deviation, and velocity on the mediolateral and anteroposterior axes of center of pressure were measured. [Results] In balance assessment with eyes open, there were significant differences between groups according to hip joint angle, except for maximum deviation on the anteroposterior axis. In balance assessment with eyes closed, there were significant differences between total length measurements at 0° and 30°, 60° and between 30° and 90°. There were significant differences between sway velocity measurements at 0° and 30° and between 30° and 90°. [Conclusion] Thus, there were differences in static balance according to hip joint angle. It is necessary to clearly identify the hip joint angle during one-leg standing testing.

Quantifying Learning in Young Infants: Tracking Leg Actions During a Discovery-learning Task.

PubMed

Sargent, Barbara; Reimann, Hendrik; Kubo, Masayoshi; Fetters, Linda

2015-06-01

Task-specific actions emerge from spontaneous movement during infancy. It has been proposed that task-specific actions emerge through a discovery-learning process. Here a method is described in which 3-4 month old infants learn a task by discovery and their leg movements are captured to quantify the learning process. This discovery-learning task uses an infant activated mobile that rotates and plays music based on specified leg action of infants. Supine infants activate the mobile by moving their feet vertically across a virtual threshold. This paradigm is unique in that as infants independently discover that their leg actions activate the mobile, the infants' leg movements are tracked using a motion capture system allowing for the quantification of the learning process. Specifically, learning is quantified in terms of the duration of mobile activation, the position variance of the end effectors (feet) that activate the mobile, changes in hip-knee coordination patterns, and changes in hip and knee muscle torque. This information describes infant exploration and exploitation at the interplay of person and environmental constraints that support task-specific action. Subsequent research using this method can investigate how specific impairments of different populations of infants at risk for movement disorders influence the discovery-learning process for task-specific action.

Muscle activity and spine load during anterior chain whole body linkage exercises: the body saw, hanging leg raise and walkout from a push-up.

PubMed

McGill, Stuart; Andersen, Jordan; Cannon, Jordan

2015-01-01

This study examined anterior chain whole body linkage exercises, namely the body saw, hanging leg raise and walkout from a push-up. Investigation of these exercises focused on which particular muscles were challenged and the magnitude of the resulting spine load. Fourteen males performed the exercises while muscle activity, external force and 3D body segment motion were recorded. A sophisticated and anatomically detailed 3D model used muscle activity and body segment kinematics to estimate muscle force, and thus sensitivity to each individual's choice of motor control for each task. Gradations of muscle activity and spine load characteristics were observed across tasks. On average, the hanging straight leg raise created approximately 3000 N of spine compression while the body saw created less than 2500 N. The hanging straight leg raise created the highest challenge to the abdominal wall (>130% MVC in rectus abdominis, 88% MVC in external oblique). The body saw resulted in almost 140% MVC activation of the serratus anterior. All other exercises produced substantial abdominal challenge, although the body saw did so in the most spine conserving way. These findings, along with consideration of an individual's injury history, training goals and current fitness level, should assist in exercise choice and programme design.

[Effect of medicinal-cake-separated moxibustion on functional activity of back-leg and plasma substance P level in patients with lumbar disc herniation].

PubMed

Yang, Shuo; Yang, Xiao-fang; Jiang, Yu; Xiang, Kai-wei; Li, Hai-yu

2014-12-01

To observe the effect of medicinal-cake-separated moxibustion combined with acupuncture on back-leg activities and plasma substance P (SP) levels in patients with lumbar disc herniation, so as to reveal its mechanism underlying pain relief. A total of 114 patients with lumbar disc herniation were randomly divided into control group (n=56) and treatment group (n=58) according to a random digits table. Patients of the control group were treated by manual acupuncture stimulation of main acupoints Jiaji (EX-B 2), Huantiao (GB 30, affected side), Chengshan (BL 57, affected side), Kunlun (BL 60, affected side), and supplemented acupoints Yanglingquan (GB 34), Weizhong (BL 40) and Zusanli (ST 36) in combination with wheat-flour-cake separated moxibustion at the main acupoints, and patients of the treatment group were treated by medicinal-cake [Chuanwu (Radix Aconiti), Caowu (Radix Aconiti Kusnezoffii), Ruxiang (Olibanum), etc. ]-separated moxibustion in combination with manual acupuncture stimulation of the same acupoints mentioned above. Acupuncture treatment was conducted for 30 min, followed by moxibustion for 15 min. The treatment was given once daily for 10 days. The patients' back-leg functional activity ability was assessed using straight-leg raising test, and the pain state assessed using visual analogue scale (VAS) and Japanese Orthopaedic Association (JOA) scores, respectively. The therapeutic effect was evaluated by using "Crite- ria for Diagnosis and Outcome Evaluation of Clinical Disorders or Syndromes of Chinese Medicine" issued in 1994 and plasma SP content was detected by radioimmunoassay. After the therapy, the back-leg activity score and JOA score of both groups were significantly higher than those of pre-treatment in the same one group (P<0. 05, P<0. 01), and those of the treatment group were significantly higher than those of the control group (P<0.05). The VAS score of the treatment group was re- markably lower than that of the control group (P<0. 01

Dynamic legged locomotion in robots and animals

NASA Astrophysics Data System (ADS)

Raibert, Marc; Playter, Robert; Ringrose, Robert; Bailey, Dave; Leeser, Karl

1995-01-01

This report documents our study of active legged systems that balance actively and move dynamically. The purpose of this research is to build a foundation of knowledge that can lead both to the construction of useful legged vehicles and to a better understanding of how animal locomotion works. In this report we provide an update on progress during the past year. Here are the topics covered in this report: (1) Is cockroach locomotion dynamic? To address this question we created three models of cockroaches, each abstracted at a different level. We provided each model with a control system and computer simulation. One set of results suggests that 'Groucho Running,' a type of dynamic walking, seems feasible at cockroach scale. (2) How do bipeds shift weight between the legs? We built a simple planar biped robot specifically to explore this question. It shifts its weight from one curved foot to the other, using a toe-off and toe-on strategy, in conjunction with dynamic tipping. (3) 3D biped gymnastics: The 3D biped robot has done front somersaults in the laboratory. The robot changes its leg length in flight to control rotation rate. This in turn provides a mechanism for controlling the landing attitude of the robot once airborne. (4) Passively stabilized layout somersault: We have found that the passive structure of a gymnast, the configuration of masses and compliances, can stabilize inherently unstable maneuvers. This means that body biomechanics could play a larger role in controlling behavior than is generally thought. We used a physical 'doll' model and computer simulation to illustrate the point. (5) Twisting: Some gymnastic maneuvers require twisting. We are studying how to couple the biomechanics of the system to its control to produce efficient, stable twisting maneuvers.

Moving human full body and body parts detection, tracking, and applications on human activity estimation, walking pattern and face recognition

NASA Astrophysics Data System (ADS)

Chen, Hai-Wen; McGurr, Mike

2016-05-01

We have developed a new way for detection and tracking of human full-body and body-parts with color (intensity) patch morphological segmentation and adaptive thresholding for security surveillance cameras. An adaptive threshold scheme has been developed for dealing with body size changes, illumination condition changes, and cross camera parameter changes. Tests with the PETS 2009 and 2014 datasets show that we can obtain high probability of detection and low probability of false alarm for full-body. Test results indicate that our human full-body detection method can considerably outperform the current state-of-the-art methods in both detection performance and computational complexity. Furthermore, in this paper, we have developed several methods using color features for detection and tracking of human body-parts (arms, legs, torso, and head, etc.). For example, we have developed a human skin color sub-patch segmentation algorithm by first conducting a RGB to YIQ transformation and then applying a Subtractive I/Q image Fusion with morphological operations. With this method, we can reliably detect and track human skin color related body-parts such as face, neck, arms, and legs. Reliable body-parts (e.g. head) detection allows us to continuously track the individual person even in the case that multiple closely spaced persons are merged. Accordingly, we have developed a new algorithm to split a merged detection blob back to individual detections based on the detected head positions. Detected body-parts also allow us to extract important local constellation features of the body-parts positions and angles related to the full-body. These features are useful for human walking gait pattern recognition and human pose (e.g. standing or falling down) estimation for potential abnormal behavior and accidental event detection, as evidenced with our experimental tests. Furthermore, based on the reliable head (face) tacking, we have applied a super-resolution algorithm to enhance

Hip proprioceptors preferentially modulate reflexes of the leg in human spinal cord injury

PubMed Central

Onushko, Tanya; Hyngstrom, Allison

2013-01-01

Stretch-sensitive afferent feedback from hip muscles has been shown to trigger long-lasting, multijoint reflex responses in people with chronic spinal cord injury (SCI). These reflexes could have important implications for control of leg movements during functional activities, such as walking. Because the control of leg movement relies on reflex regulation at all joints of the limb, we sought to determine whether stretch of hip muscles modulates reflex activity at the knee and ankle and, conversely, whether knee and ankle stretch afferents affect hip-triggered reflexes. A custom-built servomotor apparatus was used to stretch the hip muscles in nine chronic SCI subjects by oscillating the legs about the hip joint bilaterally from 10° of extension to 40° flexion. To test whether stretch-related feedback from the knee or ankle would be affected by hip movement, patellar tendon percussions and Achilles tendon vibration were delivered when the hip was either extending or flexing. Surface electromyograms (EMGs) and joint torques were recorded from both legs. Patellar tendon percussions and Achilles tendon vibration both elicited reflex responses local to the knee or ankle, respectively, and did not influence reflex responses observed at the hip. Rather, the movement direction of the hip modulated the reflex responses local to the joint. The patellar tendon reflex amplitude was larger when the perturbation was delivered during hip extension compared with hip flexion. The response to Achilles vibration was modulated by hip movement, with an increased tonic component during hip flexion compared with extension. These results demonstrate that hip-mediated sensory signals modulate activity in distal muscles of the leg and appear to play a unique role in modulation of spastic muscle activity throughout the leg in SCI. PMID:23615544

Energy absorption as a predictor of leg impedance in highly trained females.

PubMed

Kulas, Anthony S; Schmitz, Randy J; Schultz, Sandra J; Watson, Mary Allen; Perrin, David H

2006-08-01

Although leg spring stiffness represents active muscular recruitment of the lower extremity during dynamic tasks such as hopping and running, the joint-specific characteristics comprising the damping portion of this measure, leg impedance, are uncertain. The purpose of this investigation was to assess the relationship between leg impedance and energy absorption at the ankle, knee, and hip during early (impact) and late (stabilization) phases of landing. Twenty highly trained female dancers (age = 20.3 +/- 1.4 years, height = 163.7 +/- 6.0 cm, mass = 62.1 +/- 8.1 kg) were instrumented for biomechanical analysis. Subjects performed three sets of double-leg landings from under preferred, stiff, and soft landing conditions. A stepwise linear regression analysis revealed that ankle and knee energy absorption at impact, and knee and hip energy absorption during the stabilization phases of landing explained 75.5% of the variance in leg impedance. The primary predictor of leg impedance was knee energy absorption during the stabilization phase, independently accounting for 55% of the variance. Future validation studies applying this regression model to other groups of individuals are warranted.

Restless legs syndrome.

PubMed

Ekbom, Karl; Ulfberg, J

2009-11-01

Restless legs syndrome (RLS) is a common neurological sensory-motor disorder that is characterized by intense restlessness and unpleasant creeping sensations deep inside the lower legs. Symptoms appear when the legs are at rest and are worst in the evening and at night. They force patients to keep moving their legs, and often to get out of bed and wander about. Periodic limb movements (PLMS) are also common during sleep amongst those suffering from RLS, and sleep efficiency is severely reduced. There are idiopathic as well as symptomatic forms of RLS, the latter being associated with e.g. pregnancy, iron deficiency and chronic renal failure. A family history of RLS is very common and pedigrees in these cases suggest an autosomal-dominant transmission with high penetrance. Genetic investigations have been performed in order to identify genes associated with RLS. Several loci have been found (on chromosomes 12q, 14q, 9p, 2q, 20p and 16p). Pathophysiology of RLS remains incompletely understood. However, advanced brain imaging studies and positive results of dopaminergic treatment suggest that RLS may be generated by dopamine dysfunction locally within the central nervous system. At present, there is a wide range of treatment options including levodopa, dopamine agonists, opioids, benzodiazepines, antiepileptic drugs and iron supplements.

The Motor and the Brake of the Trailing Leg in Human Walking: Leg Force Control Through Ankle Modulation and Knee Covariance

PubMed Central

Toney, Megan E.; Chang, Young-Hui

2016-01-01

Human walking is a complex task, and we lack a complete understanding of how the neuromuscular system organizes its numerous muscles and joints to achieve consistent and efficient walking mechanics. Focused control of select influential task-level variables may simplify the higher-level control of steady state walking and reduce demand on the neuromuscular system. As trailing leg power generation and force application can affect the mechanical efficiency of step-to-step transitions, we investigated how joint torques are organized to control leg force and leg power during human walking. We tested whether timing of trailing leg force control corresponded with timing of peak leg power generation. We also applied a modified uncontrolled manifold analysis to test whether individual or coordinated joint torque strategies most contributed to leg force control. We found that leg force magnitude was adjusted from step-to-step to maintain consistent leg power generation. Leg force modulation was primarily determined by adjustments in the timing of peak ankle plantar-flexion torque, while knee torque was simultaneously covaried to dampen the effect of ankle torque on leg force. We propose a coordinated joint torque control strategy in which the trailing leg ankle acts as a motor to drive leg power production while trailing leg knee torque acts as a brake to refine leg power production. PMID:27334888

Strategies for diagnosing leg oedema in primary care: a qualitative study of GPs' approaches.

PubMed

Diederich, Judith; Hartel, Simone; Baum, Erika; Bösner, Stefan

2014-12-01

The symptom leg oedema represents a broad range of possible underlying aetiologies. The background of leg oedema is multifactorial and usually the GP is the first contact point for patients presenting with this symptom. GPs rely on patient history and physical examination as their main diagnostic tools. To identify GPs' diagnostic approaches and heuristics in patients presenting with leg oedema. Interviews with 15 GPs (20-30 min) using a semi-structured interview-guideline were conducted. GPs described their individual diagnostic strategies concerning all patients presenting with leg oedema they had prospectively identified during the previous four weeks. Interviews were taped and transcribed verbatim. Qualitative analysis was conducted by two independent raters. GPs applied a variety of diagnostic approaches, which can be grouped in active and passive strategies. Active strategies comprised the use of decision rules and guidelines, Bayesian arguing, problem dichotomisation and discrepancy heuristics. Passive approaches included test of time, therapy as diagnosis, and taking patient assumptions into account. When dealing with leg oedema, GPs use prior information of individual patients in a specific way. There is a broad variety of diagnostic approaches that can be grouped in 'active' and 'passive' behaviour. Approaches mostly match with established diagnostic strategies in primary care.

A comparison of the effectiveness of a game informed online learning activity and face to face teaching in increasing knowledge about managing aggression in health settings.

PubMed

McKenzie, Karen

2013-12-01

The present study compared the impact of face to face teaching with a short online game informed learning activity on health participants' knowledge about, and confidence in, managing aggressive situations. Both forms of teaching resulted in a significant increase in participants' knowledge and confidence. Face to face training led to significantly greater increases in knowledge but was equivalent in terms of confidence. Both forms of teaching were rated positively, but face to face teaching received significantly higher ratings than the online activity. The study suggests that short online game informed learning activities may offer an effective alternative for health professional training where face to face training is not possible. Further research is needed on the longer term impact of both types of training on practice.

A colored leg banding technique for Amazona parrots

USGS Publications Warehouse

Meyers, J.M.

1995-01-01

A technique for individual identification of Amazona was developed using plastic leg bands. Bands were made from 5- and 7-mm-wide strips of laminated PVC coiled 2.5 times with an inside diameter 4-5 mm gt the maximum diameter of the parrot's leg. Seventeen parrots were captured in Puerto Rico, marked with individual plastic leg bands, and observed for 204-658 d with only one lost or damaged plastic band. Plastic leg bands did not cause injury to or calluses on parrots' legs. The plastic material used for making leg bands was available in 18 colors in 1994, which would allow unique marking of 306 individuals using one plastic leg band on each leg.

Nonlinear dynamics near resonances of a rotor-active magnetic bearings system with 16-pole legs and time varying stiffness

NASA Astrophysics Data System (ADS)

Wu, R. Q.; Zhang, W.; Yao, M. H.

2018-02-01

In this paper, we analyze the complicated nonlinear dynamics of rotor-active magnetic bearings (rotor-AMB) with 16-pole legs and the time varying stiffness. The magnetic force with 16-pole legs is obtained by applying the electromagnetic theory. The governing equation of motion for rotor-active magnetic bearings is derived by using the Newton's second law. The resulting dimensionless equation of motion for the rotor-AMB system is expressed as a two-degree-of-freedom nonlinear system including the parametric excitation, quadratic and cubic nonlinearities. The averaged equation of the rotor-AMB system is obtained by using the method of multiple scales when the primary parametric resonance and 1/2 subharmonic resonance are taken into account. From the frequency-response curves, it is found that there exist the phenomena of the soft-spring type nonlinearity and the hardening-spring type nonlinearity in the rotor-AMB system. The effects of different parameters on the nonlinear dynamic behaviors of the rotor-AMB system are investigated. The numerical results indicate that the periodic, quasi-periodic and chaotic motions occur alternately in the rotor-AMB system.

Foot, leg, and ankle swelling

MedlinePlus

... feet - legs; Ankle swelling; Foot swelling; Leg swelling; Edema - peripheral; Peripheral edema ... 31. Trayes KP, Studdiford JS, Pickle S, Tully AS. Edema: diagnosis and management. Am Fam Physician . 2013;88( ...

Pipe crawler with extendable legs

DOEpatents

Zollinger, William T.

1992-01-01

A pipe crawler for moving through a pipe in inchworm fashion having front and rear leg assemblies separated by air cylinders to increase and decrease the spacing between assemblies. Each leg of the four legs of an assembly is moved between a wall-engaging, extended position and a retracted position by a separate air cylinder. The air cylinders of the leg assemblies are preferably arranged in pairs of oppositely directed cylinders with no pair lying in the same axial plane as another pair. Therefore, the cylinders can be as long a leg assembly is wide and the crawler can crawl through sections of pipes where the diameter is twice that of other sections. The crawler carries a valving system, a manifold to distribute air supplied by a single umbilical air hose to the various air cylinders in a sequence controlled electrically by a controller. The crawler also utilizes a rolling mechanism, casters in this case, to reduce friction between the crawler and pipe wall thereby further extending the range of the pipe crawler.

Pipe crawler with extendable legs

DOEpatents

Zollinger, W.T.

1992-06-16

A pipe crawler for moving through a pipe in inchworm fashion having front and rear leg assemblies separated by air cylinders to increase and decrease the spacing between assemblies. Each leg of the four legs of an assembly is moved between a wall-engaging, extended position and a retracted position by a separate air cylinder. The air cylinders of the leg assemblies are preferably arranged in pairs of oppositely directed cylinders with no pair lying in the same axial plane as another pair. Therefore, the cylinders can be as long as a leg assembly is wide and the crawler can crawl through sections of pipes where the diameter is twice that of other sections. The crawler carries a valving system, a manifold to distribute air supplied by a single umbilical air hose to the various air cylinders in a sequence controlled electrically by a controller. The crawler also utilizes a rolling mechanism, casters in this case, to reduce friction between the crawler and pipe wall thereby further extending the range of the pipe crawler. 8 figs.

Pipe crawler with extendable legs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zollinger, W.T.

1992-06-16

A pipe crawler for moving through a pipe in inchworm fashion having front and rear leg assemblies separated by air cylinders to increase and decrease the spacing between assemblies. Each leg of the four legs of an assembly is moved between a wall-engaging, extended position and a retracted position by a separate air cylinder. The air cylinders of the leg assemblies are preferably arranged in pairs of oppositely directed cylinders with no pair lying in the same axial plane as another pair. Therefore, the cylinders can be as long as a leg assembly is wide and the crawler can crawlmore » through sections of pipes where the diameter is twice that of other sections. The crawler carries a valving system, a manifold to distribute air supplied by a single umbilical air hose to the various air cylinders in a sequence controlled electrically by a controller. The crawler also utilizes a rolling mechanism, casters in this case, to reduce friction between the crawler and pipe wall thereby further extending the range of the pipe crawler. 8 figs.« less

Teaching retirement financial literacy in an undergraduate gerontology classroom: broadening the concept of the tripod or three-legged stool of retirement income utilizing active learning.

PubMed

Baker, Hallie E; Brown, Pamela Pitman

2015-01-01

The three-legged stool concept is widely used in gerontological and geriatric education as an explanation on how one should fiscally approach his or her retirement. Financial managers, planners, retirees, business owners, even the Social Security Administration uses this metaphor of fiscal soundness in retirement planning. Gerontologists are moving away from the "tripod of retirement income" and "three-legged stool" term, as more often market work is needed for financial security. This activity focuses on the tripod or three-legged stool concepts of retirement planning using active learning, allowing the students to work collaboratively in a group, reflect upon the activity, and most importantly have fun. The game also allows for an expansion of the tripod concepts into the four pillars of economic security, broaching the use of personal assets and the possible need for longer employment. Game scenarios also emphasize macro- and microlevel forces, such as race, gender, health status, education, or marital status, which can influence timing of retirement or the level of retirement income available. The authors include instructions on how to set up the learning experience including worksheets, as well as reflection questions posed throughout the process.

The Benslimane's Artistic Model for Leg Beauty.

PubMed

Benslimane, Fahd

2012-08-01

In 2000, the author started observing legs considered to be attractive. The goal was to have an ideal aesthetic model and compare the disparity between this model and a patient's reality. This could prove helpful during leg sculpturing to get closer to this ideal. Postoperatively, the result could then be compared to the ideal curves of the model legs and any remaining deviations from the ideal curves could be pointed out and eventually corrected in a second session. The lack of anthropometric studies of legs from the knee to the ankle led the author to select and study attractive legs to find out the common denominators of their beauty. The study consisted in analyzing the features that make legs look attractive. The legs of models in magazines were scanned and inserted into a PowerPoint program. The legs of live models, Barbie dolls, and athletes were photographed. Artistic drawings by Leonardo da Vinci were reviewed and Greek sculptures studied. Sculptures from the National Archaeological Museum of Athens were photographed and included in the PowerPoint program. This study shows that the first criterion for beautiful legs is the straightness of the leg column. Not a single attractive leg was found to deviate from the vertical, and each was in absolute continuity with the thigh. The second criterion is the similarity of curve distribution and progression from knee to ankle. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors at www.springer.com/00266.

On the Biomimetic Design of Agile-Robot Legs

PubMed Central

Garcia, Elena; Arevalo, Juan Carlos; Muñoz, Gustavo; Gonzalez-de-Santos, Pablo

2011-01-01

The development of functional legged robots has encountered its limits in human-made actuation technology. This paper describes research on the biomimetic design of legs for agile quadrupeds. A biomimetic leg concept that extracts key principles from horse legs which are responsible for the agile and powerful locomotion of these animals is presented. The proposed biomimetic leg model defines the effective leg length, leg kinematics, limb mass distribution, actuator power, and elastic energy recovery as determinants of agile locomotion, and values for these five key elements are given. The transfer of the extracted principles to technological instantiations is analyzed in detail, considering the availability of current materials, structures and actuators. A real leg prototype has been developed following the biomimetic leg concept proposed. The actuation system is based on the hybrid use of series elasticity and magneto-rheological dampers which provides variable compliance for natural motion. From the experimental evaluation of this prototype, conclusions on the current technological barriers to achieve real functional legged robots to walk dynamically in agile locomotion are presented. PMID:22247667

On the biomimetic design of agile-robot legs.

PubMed

Garcia, Elena; Arevalo, Juan Carlos; Muñoz, Gustavo; Gonzalez-de-Santos, Pablo

2011-01-01

The development of functional legged robots has encountered its limits in human-made actuation technology. This paper describes research on the biomimetic design of legs for agile quadrupeds. A biomimetic leg concept that extracts key principles from horse legs which are responsible for the agile and powerful locomotion of these animals is presented. The proposed biomimetic leg model defines the effective leg length, leg kinematics, limb mass distribution, actuator power, and elastic energy recovery as determinants of agile locomotion, and values for these five key elements are given. The transfer of the extracted principles to technological instantiations is analyzed in detail, considering the availability of current materials, structures and actuators. A real leg prototype has been developed following the biomimetic leg concept proposed. The actuation system is based on the hybrid use of series elasticity and magneto-rheological dampers which provides variable compliance for natural motion. From the experimental evaluation of this prototype, conclusions on the current technological barriers to achieve real functional legged robots to walk dynamically in agile locomotion are presented.

Feature extraction for face recognition via Active Shape Model (ASM) and Active Appearance Model (AAM)

NASA Astrophysics Data System (ADS)

Iqtait, M.; Mohamad, F. S.; Mamat, M.

2018-03-01

Biometric is a pattern recognition system which is used for automatic recognition of persons based on characteristics and features of an individual. Face recognition with high recognition rate is still a challenging task and usually accomplished in three phases consisting of face detection, feature extraction, and expression classification. Precise and strong location of trait point is a complicated and difficult issue in face recognition. Cootes proposed a Multi Resolution Active Shape Models (ASM) algorithm, which could extract specified shape accurately and efficiently. Furthermore, as the improvement of ASM, Active Appearance Models algorithm (AAM) is proposed to extracts both shape and texture of specified object simultaneously. In this paper we give more details about the two algorithms and give the results of experiments, testing their performance on one dataset of faces. We found that the ASM is faster and gains more accurate trait point location than the AAM, but the AAM gains a better match to the texture.

Face Preference in Infancy and Its Relation to Motor Activity

ERIC Educational Resources Information Center

Libertus, Klaus; Needham, Amy

2014-01-01

Infants' preference for faces was investigated in a cross-sectional sample of 75 children, aged 3 to 11 months, and 23 adults. A visual preference paradigm was used where pairs of faces and toys were presented side-by-side while eye gaze was recorded. In addition, motor activity was assessed via parent report and the relation between motor…

Female PFP patients present alterations in eccentric muscle activity but not the temporal order of activation of the vastus lateralis muscle during the single leg triple hop test.

PubMed

Kalytczak, Marcelo Martins; Lucareli, Paulo Roberto Garcia; Dos Reis, Amir Curcio; Bley, André Serra; Biasotto-Gonzalez, Daniela Aparecida; Correa, João Carlos Ferrari; Politti, Fabiano

2018-04-07

This study aimed to compare the concentric and eccentric activity and the temporal order of peak activity of the hip and knee muscles between women with patellofemoral pain (PFP) and healthy women during the single leg triple hop test (SLTHT). Electromyographic (EMG) and Kinematic data were collected from 14 healthy women (CG) and 14 women diagnosed with PFP (PFG) during a single session of the single leg triple hop test. Integral surface electromyography (iEMG) data of the hip and knee muscles in eccentric and concentric phases and the length of time that each muscle needed to reach the maximal peak of muscle activity were calculated. The iEMG in the eccentric phase was significantly higher (p < 0.05) than the concentric phase, for the gluteus maximus and gluteus medius muscles (CG and PFG) and for the vastus lateralis muscle (PFG). The vastus lateralis muscle was the first muscle to reach the highest peak of activity in the PFG, and the third to reach this peak in the CG. In the present study, the activity of the vastus lateralis muscle during the eccentric phase of the jump was greater than concentric phase, as a temporal anticipation of its peak in activity among women with PFP. Copyright © 2018 Elsevier B.V. All rights reserved.

Passive zero-gravity leg restraint

NASA Technical Reports Server (NTRS)

Miller, Christopher R. (Inventor)

1989-01-01

A passive zero or microgravity leg restraint is described which includes a central support post with a top and a bottom. Extending from the central support post are a calf pad tab, to which calf pad is attached, and a foot pad tab, to which foot tab is attached. Also extending from central support post are knee pads. When the restraint is in use the user's legs are forced between pads by a user imposed scissors action of the legs. The user's body is then supported in a zero or microgravity neutral body posture by the leg restraint. The calf pad has semi-ridig elastic padding material covering structural stiffener. The foot pad has padding material and a structural stiffener. Knee pads have s structural tube stiffener at their core.

Why a mosquito leg possesses superior load-bearing capacity on water: Experimentals

NASA Astrophysics Data System (ADS)

Kong, Xiang-Qing; Liu, Jian-Lin; Wu, Cheng-Wei

2016-04-01

Mosquitoes possess the striking ability to walk on water because each of their legs has a huge water supporting force (WSF) that is 23 times their body weight. Aiming at a full understanding of the origins of this extremely large force, in this study, we concentrate on two aspects of it: the intrinsic properties of the leg surface and the active control of the initial stepping angle of the whole leg. Using a measurement system that we developed ourselves, the WSFs for the original leg samples are compared with those whose surface wax and microstructures have been removed and with those of a different stiffness. The results show that leg flexibility plays a dominant role over surface wax and microstructures on the leg surface in creating the supporting force. Moreover, we discuss the dependence relationship between the maximum WSF and the initial stepping angle, which indicates that the mosquito can regulate this angle to increase or decrease the WSF during landing or takeoff. These findings are helpful for uncovering the locomotion mechanism of aquatic insects and for providing inspiration for the design of microfluids, miniature boats, biomimetic robots, and microsensors.

Bioinspired legged-robot based on large deformation of flexible skeleton.

PubMed

Mayyas, Mohammad

2014-11-11

In this article we present STARbot, a bioinspired legged robot capable of multiple locomotion modalities by using large deformation of its skeleton. We construct STARbot by using origami-style folding of flexible laminates. The long-term goal is to provide a robotic platform with maximum mobility on multiple surfaces. This paper particularly studies the quasistatic model of STARbot's leg under different conditions. We describe the large elastic deformation of a leg under external force, payload, and friction by using a set of non-dimensional, nonlinear approximate equations. We developed a test mechanism that models the motion of a leg in STARbot. We augmented several foot shapes and then tested them on soft to rough grounds. Both simulation and experimental findings were in good agreement. We utilized the model to develop several scales of tri and quad STARbot. We demonstrated the capability of these robots to locomote by combining their leg deformations with their foot motions. The combination provided a design platform for an active suspension STARbot with controlled foot locomotion. This included the ability of STARbot to change size, run over obstacles, walk and slide. Furthermore, in this paper we discuss a cost effective manufacturing and production method for manufacturing STARbot.

Why do flamingos stand on one leg?

PubMed

Anderson, Matthew J; Williams, Sarah A

2010-01-01

A series of observational studies of captive Caribbean flamingos Phoenicopterus ruber were conducted to determine why flamingos rest on one leg. While frequently asked by the general public, this basic question has remained unanswered by the scientific community. Here we suggest that the latency of flamingos to initiate forward locomotion following resting on one leg is significantly longer than following resting on two, discounting the possibility that unipedal resting reduces muscle fatigue or enhances predatory escape. Additionally, we demonstrate that flamingos do not display lateral preferences at the individual or group levels when resting on one leg, with each bird dividing its resting time across both legs. We show that while flamingos prefer resting on one leg to two regardless of location, the percentage of birds resting on one leg is significantly higher among birds standing in the water than among those on land. Finally, we demonstrate a negative relationship between temperature and the percentage of observed birds resting on one leg, such that resting on one leg decreases as temperature rises. Results strongly suggest that unipedal resting aids flamingos in thermoregulation. (c) 2009 Wiley-Liss, Inc.

A torsional MRE joint for a C-shaped robotic leg

NASA Astrophysics Data System (ADS)

Christie, M. D.; Sun, S. S.; Ning, D. H.; Du, H.; Zhang, S. W.; Li, W. H.

2017-01-01

Serving to improve stability and energy efficiency during locomotion, in nature, animals modulate their leg stiffness to adapt to their terrain. Now incorporated into many locomotive robot designs, such compliance control can enable disturbance rejection and improved transition between changing ground conditions. This paper presents a novel design of a variable stiffness leg utilizing a magnetorheological elastomer joint in a literal rolling spring loaded inverted pendulum (R-SLIP) morphology. Through the semi-active control of this hybrid permanent-magnet and coil design, variable stiffness is realized, offering a design which is capable of both softening and stiffening in an adaptive sort of way, with a maximum stiffness change of 48.0%. Experimental characterization first serves to assess the stiffness variation capacity of the torsional joint, and through later comparison with force testing of the leg, the linear stiffness is characterized with the R-SLIP-like behavior of the leg being demonstrated. Through the force relationships applied, a generalized relationship for determining linear stiffness based on joint rotation angle is also proposed, further aiding experimental validation.

Pipe crawler with extendable legs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zollinger, W.T.

1991-04-02

This invention is comprised of a pipe crawler for moving through a pipe in inchworm fashion having front and rear leg assemblies separated by air cylinders to increase and decrease the spacing. between assemblies. Each leg of the four legs of an assembly is moved between a wall-engaging, extended position and a retracted position by a separate air cylinder. The air cylinders of the leg assemblies are preferably arranged in pairs of oppositely directed cylinders with no pair laying in the same axial plane as another pair. Therefore, the cylinders can be as long as a leg assembly is widemore » and the crawler can crawl through sections of pipes where the diameter is twice that of other sections. The crawler carries a valving system, a manifold to distribute air supplied by a single umbilical air hose to the various air cylinders in a sequence controlled electrically by a controller. The crawler also utilizes a rolling mechanism, casters in this case, to reduce friction between the crawler and pipe wall thereby further extending the range of the pipe crawler.« less

Intersubject Variability in Fearful Face Processing: The Link Between Behavior and Neural Activation

PubMed Central

Doty, Tracy J.; Japee, Shruti; Ingvar, Martin; Ungerleider, Leslie G.

2014-01-01

Stimuli that signal threat show considerable variability in the extent to which they enhance behavior, even among healthy individuals. However, the neural underpinning of this behavioral variability is not well understood. By manipulating expectation of threat in an fMRI study of fearful vs. neutral face categorization, we uncovered a network of areas underlying variability in threat processing in healthy adults. We explicitly altered expectation by presenting face images at three different expectation levels: 80%, 50%, and 20%. Subjects were instructed to report as fast and as accurately as possible whether the face was fearful (signaled threat) or not. An uninformative cue preceded each face by 4 seconds (s). By taking the difference between response times (RT) to fearful compared to neutral faces, we quantified an overall fear RT bias (i.e. faster to fearful than neutral faces) for each subject. This bias correlated positively with late trial fMRI activation (8 s after the face) during unexpected fearful face trials in bilateral ventromedial prefrontal cortex, the left subgenual cingulate cortex, and the right caudate nucleus and correlated negatively with early trial fMRI activation (4 s after the cue) during expected neutral face trials in bilateral dorsal striatum and the right ventral striatum. These results demonstrate that the variability in threat processing among healthy adults is reflected not only in behavior but also in the magnitude of activation in medial prefrontal and striatal regions that appear to encode affective value. PMID:24841078

Intersubject variability in fearful face processing: the link between behavior and neural activation.

PubMed

Doty, Tracy J; Japee, Shruti; Ingvar, Martin; Ungerleider, Leslie G

2014-12-01

Stimuli that signal threat show considerable variability in the extents to which they enhance behavior, even among healthy individuals. However, the neural underpinning of this behavioral variability is not well understood. By manipulating expectation of threat in an fMRI study of fearful versus neutral face categorization, we uncovered a network of areas underlying variability in threat processing in healthy adults. We explicitly altered expectations by presenting face images at three different expectation levels: 80 %, 50 %, and 20 %. Subjects were instructed to report as quickly and accurately as possible whether the face was fearful (signaled threat) or not. An uninformative cue preceded each face by 4 s. By taking the difference between reaction times (RTs) to fearful and neutral faces, we quantified an overall fear RT bias (i.e., faster to fearful than to neutral faces) for each subject. This bias correlated positively with late-trial fMRI activation (8 s after the face) during unexpected-fearful-face trials in bilateral ventromedial prefrontal cortex, the left subgenual cingulate cortex, and the right caudate nucleus, and correlated negatively with early-trial fMRI activation (4 s after the cue) during expected-neutral-face trials in bilateral dorsal striatum and the right ventral striatum. These results demonstrate that the variability in threat processing among healthy adults is reflected not only in behavior, but also in the magnitude of activation in medial prefrontal and striatal regions that appear to encode affective value.

The Legs Problem--For All Ages

ERIC Educational Resources Information Center

Way, Jenni

2005-01-01

This article presents an example of a versatile multi-solution problem that can be used right across the primary years. The basic problem is: "Noah saw 16 legs go past him into the Ark. How many creatures did he see?" Any even number can be used, although, 2 legs allows only one answer and with 16 legs there are already 14 different…

Abnormal Neural Activation to Faces in the Parents of Children with Autism

PubMed Central

Yucel, G. H.; Belger, A.; Bizzell, J.; Parlier, M.; Adolphs, R.; Piven, J.

2015-01-01

Parents of children with an autism spectrum disorder (ASD) show subtle deficits in aspects of social behavior and face processing, which resemble those seen in ASD, referred to as the “Broad Autism Phenotype ” (BAP). While abnormal activation in ASD has been reported in several brain structures linked to social cognition, little is known regarding patterns in the BAP. We compared autism parents with control parents with no family history of ASD using 2 well-validated face-processing tasks. Results indicated increased activation in the autism parents to faces in the amygdala (AMY) and the fusiform gyrus (FG), 2 core face-processing regions. Exploratory analyses revealed hyper-activation of lateral occipital cortex (LOC) bilaterally in autism parents with aloof personality (“BAP+”). Findings suggest that abnormalities of the AMY and FG are related to underlying genetic liability for ASD, whereas abnormalities in the LOC and right FG are more specific to behavioral features of the BAP. Results extend our knowledge of neural circuitry underlying abnormal face processing beyond those previously reported in ASD to individuals with shared genetic liability for autism and a subset of genetically related individuals with the BAP. PMID:25056573

Multisystemic Sarcoidosis Presenting as Pretibial Leg Ulcers.

PubMed

Wollina, Uwe; Baunacke, Anja; Hansel, Gesina

2016-09-01

Sarcoidosis is a multisystemic disease of unknown etiology. Up to 30% of patients develop cutaneous manifestations, either specific or nonspecific. Ulcerating sarcoidosis leading to leg ulcers is a rare observation that may lead to confusions with other, more common types of chronic leg ulcers. We report the case of a 45-year-old female patient with chronic multisystemic sarcoidosis presenting with pretibial leg ulcers. Other etiology could be excluded. Histology revealed nonspecific findings. Therefore, the diagnosis of nonspecific leg ulcers in sarcoidosis was confirmed. Treatment consisted of oral prednisolone and good ulcer care. Complete healing was achieved within 6 months. Sarcoidosis is a rare cause of leg ulcers and usually sarcoid granulomas can be found. Our patient illustrates that even in the absence of sarcoid granulomas, leg ulcers can be due to sarcoidosis. © The Author(s) 2016.

Sparsely-distributed organization of face and limb activations in human ventral temporal cortex

PubMed Central

Weiner, Kevin S.; Grill-Spector, Kalanit

2011-01-01

Functional magnetic resonance imaging (fMRI) has identified face- and body part-selective regions, as well as distributed activation patterns for object categories across human ventral temporal cortex (VTC), eliciting a debate regarding functional organization in VTC and neural coding of object categories. Using high-resolution fMRI, we illustrate that face- and limb-selective activations alternate in a series of largely nonoverlapping clusters in lateral VTC along the inferior occipital gyrus (IOG), fusiform gyrus (FG), and occipitotemporal sulcus (OTS). Both general linear model (GLM) and multivoxel pattern (MVP) analyses show that face- and limb-selective activations minimally overlap and that this organization is consistent across experiments and days. We provide a reliable method to separate two face-selective clusters on the middle and posterior FG (mFus and pFus), and another on the IOG using their spatial relation to limb-selective activations and retinotopic areas hV4, VO-1/2, and hMT+. Furthermore, these activations show a gradient of increasing face selectivity and decreasing limb selectivity from the IOG to the mFus. Finally, MVP analyses indicate that there is differential information for faces in lateral VTC (containing weakly- and highly-selective voxels) relative to non-selective voxels in medial VTC. These findings suggest a sparsely-distributed organization where sparseness refers to the presence of several face- and limb-selective clusters in VTC, and distributed refers to the presence of different amounts of information in highly-, weakly-, and non-selective voxels. Consequently, theories of object recognition should consider the functional and spatial constraints of neural coding across a series of nonoverlapping category-selective clusters that are themselves distributed. PMID:20457261

Does a crouched leg posture enhance running stability and robustness?

PubMed

Blum, Yvonne; Birn-Jeffery, Aleksandra; Daley, Monica A; Seyfarth, Andre

2011-07-21

Humans and birds both walk and run bipedally on compliant legs. However, differences in leg architecture may result in species-specific leg control strategies as indicated by the observed gait patterns. In this work, control strategies for stable running are derived based on a conceptual model and compared with experimental data on running humans and pheasants (Phasianus colchicus). From a model perspective, running with compliant legs can be represented by the planar spring mass model and stabilized by applying swing leg control. Here, linear adaptations of the three leg parameters, leg angle, leg length and leg stiffness during late swing phase are assumed. Experimentally observed kinematic control parameters (leg rotation and leg length change) of human and avian running are compared, and interpreted within the context of this model, with specific focus on stability and robustness characteristics. The results suggest differences in stability characteristics and applied control strategies of human and avian running, which may relate to differences in leg posture (straight leg posture in humans, and crouched leg posture in birds). It has been suggested that crouched leg postures may improve stability. However, as the system of control strategies is overdetermined, our model findings suggest that a crouched leg posture does not necessarily enhance running stability. The model also predicts different leg stiffness adaptation rates for human and avian running, and suggests that a crouched avian leg posture, which is capable of both leg shortening and lengthening, allows for stable running without adjusting leg stiffness. In contrast, in straight-legged human running, the preparation of the ground contact seems to be more critical, requiring leg stiffness adjustment to remain stable. Finally, analysis of a simple robustness measure, the normalized maximum drop, suggests that the crouched leg posture may provide greater robustness to changes in terrain height

Effects of myofascial release leg pull and sagittal plane isometric contract-relax techniques on passive straight-leg raise angle.

PubMed

Hanten, W P; Chandler, S D

1994-09-01

Experimental evidence does not currently exist to support the claims of clinical effectiveness for myofascial release techniques. This presents an obvious need to document the effects of myofascial release. The purpose of this study was to compare the effects of two techniques, sagittal plane isometric contract-relax and myofascial release leg pull for increasing hip flexion range of motion (ROM) as measured by the angle of passive straight-leg raise. Seventy-five nondisabled, female subjects 18-29 years of age were randomly assigned to contract-relax, leg pull, or control groups. Pretest hip flexion ROM was measured for each subject's right hip with a passive straight-leg raise test using a fluid-filled goniometer. Subjects in the treatment groups received either contract-relax or leg pull treatment applied to the right lower extremity; subjects in the control group remained supine quietly for 5 minutes. Following treatment, posttest straight-leg raise measurements were performed. A one-way analysis of variance followed by a Newman-Keuls post hoc comparison of mean gain scores showed that subjects receiving contract-relax treatment increased their ROM significantly more than those who received leg pull treatment, and the increase in ROM of subjects in both treatment groups was significantly higher than those of the control group. The results suggest that while both contract-relax and leg pull techniques can significantly increase hip flexion ROM in normal subjects, contract-relax treatment may be more effective and efficient than leg pull treatment.

Different brain activity in response to emotional faces alone and augmented by contextual information.

PubMed

Lee, Kyung Hwa; Siegle, Greg J

2014-11-01

This study examined the extent to which emotional face stimuli differ from the neural reactivity associated with more ecological contextually augmented stimuli. Participants were scanned when they viewed contextually rich pictures depicting both emotional faces and context, and pictures of emotional faces presented alone. Emotional faces alone were more strongly associated with brain activity in paralimbic and social information processing regions, whereas emotional faces augmented by context were associated with increased and sustained activity in regions potentially representing increased complexity and subjective emotional experience. Furthermore, context effects were modulated by emotional intensity and valence. These findings suggest that cortical elaboration that is apparent in contextually augmented stimuli may be missed in studies of emotional faces alone, whereas emotional faces may more selectively recruit limbic reactivity. Copyright © 2014 Society for Psychophysiological Research.

[Replantation at lower leg level].

PubMed

Daigeler, A; Fansa, H; Westphal, T; Schneider, W

2003-11-01

Replantation in reconstructive surgery is an established procedure due to microsurgical techniques. It can be routinely performed in unilateral lower leg amputation. In some cases of bilateral amputation, in which orthotopic replantation is not possible due to the complex trauma, heterotopic replantation is a therapeutic option. This avoids prosthetic fitting. We report five cases of orthotopic and two of heterotopic lower limb replantations. Functional outcome concerning sensibility, mobility, pain, and aesthetic result were assessed clinically and using a questionnaire. Functional outcome and patient satisfaction were good. The psychological situation of the patients as well as mobility and stability of the replanted limbs were satisfying. Heterotopically replanted patients found the replanted legs superior to the prostheses. We conclude that, in lower leg amputation, attempts should be made to replant the extremity. In bilateral lower leg amputations, at least one limb should be reconstructed, even if "only" a heterotopic replantation can be performed.

Altered medial prefrontal activity during dynamic face processing in schizophrenia spectrum patients.

PubMed

Mothersill, Omar; Morris, Derek W; Kelly, Sinead; Rose, Emma Jane; Bokde, Arun; Reilly, Richard; Gill, Michael; Corvin, Aiden P; Donohoe, Gary

2014-08-01

Processing the emotional content of faces is recognised as a key deficit of schizophrenia, associated with poorer functional outcomes and possibly contributing to the severity of clinical symptoms such as paranoia. At the neural level, fMRI studies have reported altered limbic activity in response to facial stimuli. However, previous studies may be limited by the use of cognitively demanding tasks and static facial stimuli. To address these issues, the current study used a face processing task involving both passive face viewing and dynamic social stimuli. Such a task may (1) lack the potentially confounding effects of high cognitive demands and (2) show higher ecological validity. Functional MRI was used to examine neural activity in 25 patients with a DSM-IV diagnosis of schizophrenia/schizoaffective disorder and 21 age- and gender-matched healthy controls while they participated in a face processing task, which involved viewing videos of angry and neutral facial expressions, and a non-biological baseline condition. While viewing faces, patients showed significantly weaker deactivation of the medial prefrontal cortex, including the anterior cingulate, and decreased activation in the left cerebellum, compared to controls. Patients also showed weaker medial prefrontal deactivation while viewing the angry faces relative to baseline. Given that the anterior cingulate plays a role in processing negative emotion, weaker deactivation of this region in patients while viewing faces may contribute to an increased perception of social threat. Future studies examining the neurobiology of social cognition in schizophrenia using fMRI may help establish targets for treatment interventions. Copyright © 2014 Elsevier B.V. All rights reserved.

Are differences in leg length predictive of lateral patello-femoral pain?

PubMed

Carlson, Mary; Wilkerson, Jerry

2007-03-01

Lateral patello-femoral pain can shorten an athletic career and generally decrease an individual's physical activity and functional level, such as preventing stair climbing and reducing the ability to rise from a chair. Leg length inequality is associated with patello-femoral pain. A leg length test that best distinguishes the difference between people who have lateral patello-femoral pain and those who do not would have clinical utility. The purpose of the present study was, first, to determine if unilateral, lateral patello-femoral pain was associated with the longer leg when inequality of leg lengths existed and, second, to determine if leg length direct measurement, indirect measurement or quadriceps angle (Q angle) could correctly classify participants according to the presence or absence of patello-femoral pain. The study used an ex post facto, two-group quasi-experimental design. A volunteer sample of 52 participants (14 males, 38 females), ranged in age from 18 to 52 years. Three methods were used to measure leg lengths: palpation meter (PALM) on anterior superior iliac spines (ASIS) while participants maintained centred weight-bearing position on a high resolution pressure mat; tape measurement from ASIS to medial malleolus (supine); tape measurement from ASIS to lateral malleolus (supine). Additionally, Q angle was measured in supine position. Patellar grind test, medial retinacular and lateral patellar palpation screened for patello-femoral pain. Logistic regression analysis determined correctness of membership in painful and non-painful patello-femoral groups. The PALM method of indirect measurement of leg length differences overall correctly classified approximately 83 % of the participants. Tape measure to medial and lateral malleoli as well as Q angle did not yield significant results. The results suggested that the PALM method of measuring leg length differences may have clinical utility in differentiating between patients who are likely to sustain

Leg stiffness and expertise in men jumping.

PubMed

Laffaye, Guillaume; Bardy, Benoît G; Durey, Alain

2005-04-01

The aim of the present study is to investigate: a) the leg spring behavior in the one-leg vertical jump, b) the contribution of impulse parameters to this behavior, and c) the effect of jumping expertise on leg stiffness. Four categories of experts (handball, basketball, volleyball players, and Fosbury athletes), as well as novice subjects performed a run-and-jump test to touch a ball with the head. Five experimental conditions were tested from 55 to 95% of the maximum jump height. Kinematic and kinetic data were collected using six cameras and a force plate. The mechanical behavior of the musculoskeleton component of the human body can be modeled as a simple mass-spring system, from which leg stiffness values can be extracted to better understand energy transfer during running or jumping. The results indicate that leg stiffness (mean value of 11.5 kN.m) decreased with jumping height. Leg shortening at takeoff also increased with jumping height, whereas contact time decreased (-18%). No difference was found between experts and novices for leg stiffness. However, a principal components analysis (PCA) indicated the contribution of two main factors to the performance. The first factor emerged out of vertical force, stiffness, and duration of impulse. The second factor included leg shortening and jumping height. Differences between experts and novices were observed in terms of the contribution of leg stiffness to jump height, and more importantly, clear differences existed between experts in jumping parameters. The analysis performed on the sport categories indeed revealed different jumping profiles, characterized by specific, sport-related impulse parameters.

Neural Activation to Emotional Faces in Adolescents with Autism Spectrum Disorders

ERIC Educational Resources Information Center

Weng, Shih-Jen; Carrasco, Melisa; Swartz, Johnna R.; Wiggins, Jillian Lee; Kurapati, Nikhil; Liberzon, Israel; Risi, Susan; Lord, Catherine; Monk, Christopher S.

2011-01-01

Background: Autism spectrum disorders (ASD) involve a core deficit in social functioning and impairments in the ability to recognize face emotions. In an emotional faces task designed to constrain group differences in attention, the present study used functional MRI to characterize activation in the amygdala, ventral prefrontal cortex (vPFC), and…

Anatomic and functional leg-length inequality: A review and recommendation for clinical decision-making. Part II, the functional or unloaded leg-length asymmetry

PubMed Central

Knutson, Gary A

2005-01-01

Background Part II of this review examines the functional "short leg" or unloaded leg length alignment asymmetry, including the relationship between an anatomic and functional leg-length inequality. Based on the reviewed evidence, an outline for clinical decision making regarding functional and anatomic leg-length inequality will be provided. Methods Online databases: Medline, CINAHL and Mantis. Plus library searches for the time frame of 1970–2005 were done using the term "leg-length inequality". Results and Discussion The evidence suggests that an unloaded leg-length asymmetry is a different phenomenon than an anatomic leg-length inequality, and may be due to suprapelvic muscle hypertonicity. Anatomic leg-length inequality and unloaded functional or leg-length alignment asymmetry may interact in a loaded (standing) posture, but not in an unloaded (prone/supine) posture. Conclusion The unloaded, functional leg-length alignment asymmetry is a likely phenomenon, although more research regarding reliability of the measurement procedure and validity relative to spinal dysfunction is needed. Functional leg-length alignment asymmetry should be eliminated before any necessary treatment of anatomic LLI. PMID:16080787

Ankle Joint Angle and Lower Leg Musculotendinous Unit Responses to Cryotherapy.

PubMed

Akehi, Kazuma; Long, Blaine C; Warren, Aric J; Goad, Carla L

2016-09-01

Akehi, K, Long, BC, Warren, AJ, and Goad, CL. Ankle joint angle and lower leg musculotendinous unit responses to cryotherapy. J Strength Cond Res 30(9): 2482-2492, 2016-The use of cold application has been debated for its influence on joint range of motion (ROM) and stiffness. The purpose of this study was to determine whether a 30-minute ice bag application to the plantarflexor muscles or ankle influences passive ankle dorsiflexion ROM and lower leg musculotendinous stiffness (MTS). Thirty-five recreationally active college-aged individuals with no history of lower leg injury 6 months before data collection volunteered. On each testing day, we measured maximum passive ankle dorsiflexion ROM (°) and plantarflexor torque (N·m) on an isokinetic dynamometer to calculate the passive plantarflexor MTS (N·m per degree) at 4 joint angles before, during, and after a treatment. Surface electromyography amplitudes (μV), and skin surface and ambient air temperature (°C) were also measured. Subjects received an ice bag to the posterior lower leg, ankle joint, or nothing for 30 minutes in different days. Ice bag application to the lower leg and ankle did not influence passive ROM (F(12,396) = 0.67, p = 0.78). Passive torque increased after ice bag application to the lower leg (F(12,396) = 2.21, p = 0.011). Passive MTS at the initial joint angle increased after ice bag application to the lower leg (F(12,396) = 2.14, p = 0.014) but not at the other joint angles (p > 0.05). Surface electromyography amplitudes for gastrocnemius and soleus muscles increased after ice application to the lower leg (F(2,66) = 5.61, p = 0.006; F(12,396) = 3.60, p < 0.001). Ice bag application to the lower leg and ankle joint does not alter passive dorsiflexion ROM but increases passive ankle plantarflexor torque in addition to passive ankle plantarflexor MTS at the initial joint angle.

Abnormal Neural Activation to Faces in the Parents of Children with Autism.

PubMed

Yucel, G H; Belger, A; Bizzell, J; Parlier, M; Adolphs, R; Piven, J

2015-12-01

Parents of children with an autism spectrum disorder (ASD) show subtle deficits in aspects of social behavior and face processing, which resemble those seen in ASD, referred to as the "Broad Autism Phenotype " (BAP). While abnormal activation in ASD has been reported in several brain structures linked to social cognition, little is known regarding patterns in the BAP. We compared autism parents with control parents with no family history of ASD using 2 well-validated face-processing tasks. Results indicated increased activation in the autism parents to faces in the amygdala (AMY) and the fusiform gyrus (FG), 2 core face-processing regions. Exploratory analyses revealed hyper-activation of lateral occipital cortex (LOC) bilaterally in autism parents with aloof personality ("BAP+"). Findings suggest that abnormalities of the AMY and FG are related to underlying genetic liability for ASD, whereas abnormalities in the LOC and right FG are more specific to behavioral features of the BAP. Results extend our knowledge of neural circuitry underlying abnormal face processing beyond those previously reported in ASD to individuals with shared genetic liability for autism and a subset of genetically related individuals with the BAP. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Congruence of happy and sad emotion in music and faces modifies cortical audiovisual activation.

PubMed

Jeong, Jeong-Won; Diwadkar, Vaibhav A; Chugani, Carla D; Sinsoongsud, Piti; Muzik, Otto; Behen, Michael E; Chugani, Harry T; Chugani, Diane C

2011-02-14

The powerful emotion inducing properties of music are well-known, yet music may convey differing emotional responses depending on environmental factors. We hypothesized that neural mechanisms involved in listening to music may differ when presented together with visual stimuli that conveyed the same emotion as the music when compared to visual stimuli with incongruent emotional content. We designed this study to determine the effect of auditory (happy and sad instrumental music) and visual stimuli (happy and sad faces) congruent or incongruent for emotional content on audiovisual processing using fMRI blood oxygenation level-dependent (BOLD) signal contrast. The experiment was conducted in the context of a conventional block-design experiment. A block consisted of three emotional ON periods, music alone (happy or sad music), face alone (happy or sad faces), and music combined with faces where the music excerpt was played while presenting either congruent emotional faces or incongruent emotional faces. We found activity in the superior temporal gyrus (STG) and fusiform gyrus (FG) to be differentially modulated by music and faces depending on the congruence of emotional content. There was a greater BOLD response in STG when the emotion signaled by the music and faces was congruent. Furthermore, the magnitude of these changes differed for happy congruence and sad congruence, i.e., the activation of STG when happy music was presented with happy faces was greater than the activation seen when sad music was presented with sad faces. In contrast, incongruent stimuli diminished the BOLD response in STG and elicited greater signal change in bilateral FG. Behavioral testing supplemented these findings by showing that subject ratings of emotion in faces were influenced by emotion in music. When presented with happy music, happy faces were rated as more happy (p=0.051) and sad faces were rated as less sad (p=0.030). When presented with sad music, happy faces were rated as less

Broken Leg

MedlinePlus

... devices into the broken bone to maintain proper alignment during healing. Other injuries may be treated with ... that extend into the joint and poor bone alignment can cause osteoarthritis years later. If your leg ...

The Interday Measurement Consistency of and Relationships Between Hamstring and Leg Musculo-articular Stiffness.

PubMed

Waxman, Justin P; Schmitz, Randy J; Shultz, Sandra J

2015-10-01

Hamstring stiffness (K(HAM)) and leg stiffness (K(LEG)) are commonly examined relative to athletic performance and injury risk. Given these may be modifiable, it is important to understand day-to-day variations inherent in these measures before use in training studies. In addition, the extent to which K(HAM) and K(LEG) measure similar active stiffness characteristics has not been established. We investigated the interday measurement consistency of K(HAM) and K(LEG), and examined the extent to which K(LEG) predicted K(HAM) in 6 males and 9 females. K(HAM) was moderately consistent day-to-day (ICC(2,5) = .71; SEM = 76.3 N·m(-1)), and 95% limits of agreement (95% LOA) revealed a systematic bias with considerable absolute measurement error (95% LOA = 89.6 ± 224.8 N·m(-1)). Day-to-day differences in procedural factors explained 59.4% of the variance in day-to-day differences in K(HAM). Bilateral and unilateral K(LEG) was more consistent (ICC(2,3) range = .87-.94; SEM range = 1.0-2.91 kN·m(-1)) with lower absolute error (95% LOA bilateral= -2.0 ± 10.3; left leg = -0.36 ± 3.82; right leg = -1.05 ± 3.61 kN·m(-1)). K(LEG) explained 44% of the variance in K(HAM) (P < .01). Findings suggest that procedural factors must be carefully controlled to yield consistent and precise K(HAM) measures. The ease and consistency of K(LEG), and moderate correlation with K(HAM), may steer clinicians toward K(LEG) when measuring lower-extremity stiffness for screening studies and monitoring the effectiveness of training interventions over time.

Air Current Applied to the Face Improves Exercise Performance in Patients with COPD.

PubMed

Marchetti, Nathaniel; Lammi, Matthew R; Travaline, John M; Ciccolella, David; Civic, Brian; Criner, Gerard J

2015-10-01

Improving dyspnea and exercise performance are goals of COPD therapy. We tested the hypothesis that air current applied to the face would lessen dyspnea and improve exercise performance in moderate-severe COPD patients. We recruited 10 COPD patients (5 men, age 62 ± 6 years, FEV1 0.93 ± 0.11 L (34 ± 3% predicted), TLC 107 ± 6%, RV 172 ± 18%) naïve to the study hypothesis. Each patient was randomized in a crossover fashion to lower extremity ergometry at constant submaximal workload with a 12-diameter fan directed at the patients face or exposed leg. Each patients' studies were separated by at least 1 week. Inspiratory capacity and Borg dyspnea score were measured every 2 min and at maximal exercise. Total exercise time was longer when the fan was directed to the face (14.3 ± 12 vs. 9.4 ± 7.6 min, face vs. leg, respectively, p = 0.03). Inspiratory capacity tended to be greater with the fan directed to the face (1.4 (0.6-3.25) vs. 1.26 (0.56-2.89) L, p = 0.06). There was a reduction in dynamic hyperinflation, as reflected by higher IRV area in the fan on face group (553 ± 562 a.u. vs. 328 ± 319 a.u., p = 0.047). There was a significant improvement in the Borg dyspnea score at maximal exercise (5.0 (0-10) vs. 6.5 (0-10), p = 0.03), despite exercising for 34 % longer with the fan directed to the face. Air current applied to the face improves exercise performance in COPD. Possible mechanisms include an alteration in breathing pattern that diminishes development of dynamic hyperinflation or to a change in perception of breathlessness.

Prosthetic leg powered by MR brake and SMA wires

NASA Astrophysics Data System (ADS)

Nguyen, The; Munguia, Vicente; Calderon, Jose

2014-04-01

Current knee designs for prosthetic legs rely on electric motors for both moving and stationary states. The electric motors draw an especially high level of current to sustain a fixed position. The advantage of using magnetorheological (MR) fluid is that it requires less current and can have a variable braking torque. Besides, the proposed prosthetic leg is actuated by NiTinol wire, a popular shape memory alloy (SMA). The incorporation of NiTinol gives the leg more realistic weight distribution with appropriate arrangement of the batteries and wires. The prosthesis in this research was designed with MR brake as stopping component and SMA wire network as actuating component at the knee. The MR brake was designed with novel non-circular shape for the rotor that improved the braking torque while minimizing the power consumption. The design also helped simplify the control of braking process. The SMA wire network was design so that the knee motion was actively rotated in both directions. The SMA wires were arranged and played very similar role as the leg's muscles. The study started with the overall solid design of the knee including both MR and SMA parts. Theoretical models were derived and programmed in Simulink for both components. The simulation was capable of predicting the power required for moving the leg or hold it in a fixed position for a certain amount of time. Subsequently, the design was prototyped and tested to validate the theoretical prediction. The theoretical models were updated accordingly to correlate with the experimental data.

Face-to-face or face-to-screen? Undergraduates' opinions and test performance in classroom vs. online learning

PubMed Central

Kemp, Nenagh; Grieve, Rachel

2014-01-01

As electronic communication becomes increasingly common, and as students juggle study, work, and family life, many universities are offering their students more flexible learning opportunities. Classes once delivered face-to-face are often replaced by online activities and discussions. However, there is little research comparing students' experience and learning in these two modalities. The aim of this study was to compare undergraduates' preference for, and academic performance on, class material and assessment presented online vs. in traditional classrooms. Psychology students (N = 67) at an Australian university completed written exercises, a class discussion, and a written test on two academic topics. The activities for one topic were conducted face-to-face, and the other online, with topics counterbalanced across two groups. The results showed that students preferred to complete activities face-to-face rather than online, but there was no significant difference in their test performance in the two modalities. In their written responses, students expressed a strong preference for class discussions to be conducted face-to-face, reporting that they felt more engaged, and received more immediate feedback, than in online discussion. A follow-up study with a separate group (N = 37) confirmed that although students appreciated the convenience of completing written activities online in their own time, they also strongly preferred to discuss course content with peers in the classroom rather than online. It is concluded that online and face-to-face activities can lead to similar levels of academic performance, but that students would rather do written activities online but engage in discussion in person. Course developers could aim to structure classes so that students can benefit from both the flexibility of online learning, and the greater engagement experienced in face-to-face discussion. PMID:25429276

Face-to-face or face-to-screen? Undergraduates' opinions and test performance in classroom vs. online learning.

PubMed

Kemp, Nenagh; Grieve, Rachel

2014-01-01

As electronic communication becomes increasingly common, and as students juggle study, work, and family life, many universities are offering their students more flexible learning opportunities. Classes once delivered face-to-face are often replaced by online activities and discussions. However, there is little research comparing students' experience and learning in these two modalities. The aim of this study was to compare undergraduates' preference for, and academic performance on, class material and assessment presented online vs. in traditional classrooms. Psychology students (N = 67) at an Australian university completed written exercises, a class discussion, and a written test on two academic topics. The activities for one topic were conducted face-to-face, and the other online, with topics counterbalanced across two groups. The results showed that students preferred to complete activities face-to-face rather than online, but there was no significant difference in their test performance in the two modalities. In their written responses, students expressed a strong preference for class discussions to be conducted face-to-face, reporting that they felt more engaged, and received more immediate feedback, than in online discussion. A follow-up study with a separate group (N = 37) confirmed that although students appreciated the convenience of completing written activities online in their own time, they also strongly preferred to discuss course content with peers in the classroom rather than online. It is concluded that online and face-to-face activities can lead to similar levels of academic performance, but that students would rather do written activities online but engage in discussion in person. Course developers could aim to structure classes so that students can benefit from both the flexibility of online learning, and the greater engagement experienced in face-to-face discussion.

Chronic leg ulceration in homozygous sickle cell disease: the role of venous incompetence.

PubMed

Clare, Andrea; FitzHenley, Michael; Harris, June; Hambleton, Ian; Serjeant, Graham R

2002-11-01

Chronic leg ulceration is a common cause of morbidity in Jamaican patients with homozygous sickle cell (SS) disease. Ulcers heal more rapidly on bed rest and deteriorate on prolonged standing, suggesting a role of venous hypertension in their persistence. This hypothesis has been tested by Doppler detection of venous competence in SS patients and in matched controls with a normal haemoglobin (AA) genotype in the Jamaican Cohort Study. Venous incompetence was significantly more frequent in SS disease [137/183 (75%)] than in non-pregnant AA controls [53/137 (39%)]. Past or present ulceration occurred in 78 (43%) SS patients, with a highly significant association between leg ulceration and venous incompetence in the same leg (P < 0.001). Prominence and/or varicosities of the veins and spontaneous leg ulcers were more common among patients with multiple sites of incompetence. The association of venous incompetence with chronic leg ulceration identifies a further pathological mechanism contributing to the morbidity of SS disease. The cause of venous incompetence is unknown but the sluggish circulation associated with dependency, turbidity and impaired linear flow at venous valves, hypoxia-induced sickling, the rheological effects of high white cell counts, and activation of components of the coagulation system may all contribute. Venous hypertension in SS patients with leg ulceration suggests that firm elastic supportive dressings might promote healing of chronic leg ulcers.

Wings versus legs in the avian bauplan: development and evolution of alternative locomotor strategies.

PubMed

Heers, Ashley M; Dial, Kenneth P

2015-02-01

Wings have long been regarded as a hallmark of evolutionary innovation, allowing insects, birds, and bats to radiate into aerial environments. For many groups, our intuitive and colloquial perspective is that wings function for aerial activities, and legs for terrestrial, in a relatively independent manner. However, insects and birds often engage their wings and legs cooperatively. In addition, the degree of autonomy between wings and legs may be constrained by tradeoffs, between allocating resources to wings versus legs during development, or between wing versus leg investment and performance (because legs must be carried as baggage by wings during flight and vice versa). Such tradeoffs would profoundly affect the development and evolution of locomotor strategies, and many related aspects of animal ecology. Here, we provide the first evaluation of wing versus leg investment, performance and relative use, in birds-both across species, and during ontogeny in three precocial species with different ecologies. Our results suggest that tradeoffs between wing and leg modules help shape ontogenetic and evolutionary trajectories, but can be offset by recruiting modules cooperatively. These findings offer a new paradigm for exploring locomotor strategies of flying organisms and their extinct precursors, and thereby elucidating some of the most spectacular diversity in animal history. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

[Acute leg compartment syndrome after exertion].

PubMed

Misović, Sidor; Kronja, Goran; Ignjatović, Dragan; Tomić, Aleksandar

2005-03-01

A case of a 22-year old soldier, with a history of pain in the leg during heavy exercise, which desisted at rest, was presented. One day before admission, the patient had felt an extreme exertion-induced pain in his right leg which had not lessenned at rest. At the same time, the patient noticed persistent severe leg edema. On physical examination, the intracompartmental pressure was 62 mmHg (> 30 mmHg). The patient was urgently operated on, and fasciotomy according to Mubarak was used. At second surgery, the debridement of the muscles of the posterior group of the leg, and the evacuation of hemathoma from the anterior and lateral group of the right leg muscles were perfomed. Postoperative recovery was uneventful. Fasciotomy wounds were closed within 14 days of the surgery. The complete physical treatment was done. Follow-up examinations 1, 3, and 6 months afterwards were satisfactory. The soldier completed his compulsory military service without any sequelae. Laboratory results were normal. Overlooked, unrecognized or surgically untreated compartment syndrome can cause severe damage, including even the loss of the extremity.

Evaluation of arm-leg coordination in flat breaststroke.

PubMed

Chollet, D; Seifert, L; Leblanc, H; Boulesteix, L; Carter, M

2004-10-01

This study proposes a new method to evaluate arm-leg coordination in flat breaststroke. Five arm and leg stroke phases were defined with a velocity-video system. Five time gaps quantified the time between arm and leg actions during three paces of a race (200 m, 100 m and 50 m) in 16 top level swimmers. Based on these time gaps, effective glide, effective propulsion, effective leg insweep and effective recovery were used to identify the different stroke phases of the body. A faster pace corresponded to increased stroke rate, decreased stroke length, increased propulsive phases, shorter glide phases, and a shorter T1 time gap, which measured the effective body glide. The top level swimmers showed short time gaps (T2, T3, T4, measuring the timing of arm-leg recoveries), which reflected the continuity in arm and leg actions. The measurement of these time gaps thus provides a pertinent evaluation of swimmers' skill in adapting their arm-leg coordination to biomechanical constraints.

Seeing faces is necessary for face-domain formation.

PubMed

Arcaro, Michael J; Schade, Peter F; Vincent, Justin L; Ponce, Carlos R; Livingstone, Margaret S

2017-10-01

Here we report that monkeys raised without exposure to faces did not develop face domains, but did develop domains for other categories and did show normal retinotopic organization, indicating that early face deprivation leads to a highly selective cortical processing deficit. Therefore, experience must be necessary for the formation (or maintenance) of face domains. Gaze tracking revealed that control monkeys looked preferentially at faces, even at ages prior to the emergence of face domains, but face-deprived monkeys did not, indicating that face looking is not innate. A retinotopic organization is present throughout the visual system at birth, so selective early viewing behavior could bias category-specific visual responses toward particular retinotopic representations, thereby leading to domain formation in stereotyped locations in inferotemporal cortex, without requiring category-specific templates or biases. Thus, we propose that environmental importance influences viewing behavior, viewing behavior drives neuronal activity, and neuronal activity sculpts domain formation.

GABAergic inhibition of leg motoneurons is required for normal walking behavior in freely moving Drosophila

PubMed Central

Gowda, Swetha B. M.; Paranjpe, Pushkar D.; Reddy, O. Venkateswara; Thiagarajan, Devasena; Palliyil, Sudhir; Reichert, Heinrich

2018-01-01

Walking is a complex rhythmic locomotor behavior generated by sequential and periodical contraction of muscles essential for coordinated control of movements of legs and leg joints. Studies of walking in vertebrates and invertebrates have revealed that premotor neural circuitry generates a basic rhythmic pattern that is sculpted by sensory feedback and ultimately controls the amplitude and phase of the motor output to leg muscles. However, the identity and functional roles of the premotor interneurons that directly control leg motoneuron activity are poorly understood. Here we take advantage of the powerful genetic methodology available in Drosophila to investigate the role of premotor inhibition in walking by genetically suppressing inhibitory input to leg motoneurons. For this, we have developed an algorithm for automated analysis of leg motion to characterize the walking parameters of wild-type flies from high-speed video recordings. Further, we use genetic reagents for targeted RNAi knockdown of inhibitory neurotransmitter receptors in leg motoneurons together with quantitative analysis of resulting changes in leg movement parameters in freely walking Drosophila. Our findings indicate that targeted down-regulation of the GABAA receptor Rdl (Resistance to Dieldrin) in leg motoneurons results in a dramatic reduction of walking speed and step length without the loss of general leg coordination during locomotion. Genetically restricting the knockdown to the adult stage and subsets of motoneurons yields qualitatively identical results. Taken together, these findings identify GABAergic premotor inhibition of motoneurons as an important determinant of correctly coordinated leg movements and speed of walking in freely behaving Drosophila. PMID:29440493

GABAergic inhibition of leg motoneurons is required for normal walking behavior in freely moving Drosophila.

PubMed

Gowda, Swetha B M; Paranjpe, Pushkar D; Reddy, O Venkateswara; Thiagarajan, Devasena; Palliyil, Sudhir; Reichert, Heinrich; VijayRaghavan, K

2018-02-27

Walking is a complex rhythmic locomotor behavior generated by sequential and periodical contraction of muscles essential for coordinated control of movements of legs and leg joints. Studies of walking in vertebrates and invertebrates have revealed that premotor neural circuitry generates a basic rhythmic pattern that is sculpted by sensory feedback and ultimately controls the amplitude and phase of the motor output to leg muscles. However, the identity and functional roles of the premotor interneurons that directly control leg motoneuron activity are poorly understood. Here we take advantage of the powerful genetic methodology available in Drosophila to investigate the role of premotor inhibition in walking by genetically suppressing inhibitory input to leg motoneurons. For this, we have developed an algorithm for automated analysis of leg motion to characterize the walking parameters of wild-type flies from high-speed video recordings. Further, we use genetic reagents for targeted RNAi knockdown of inhibitory neurotransmitter receptors in leg motoneurons together with quantitative analysis of resulting changes in leg movement parameters in freely walking Drosophila Our findings indicate that targeted down-regulation of the GABA A receptor Rdl (Resistance to Dieldrin) in leg motoneurons results in a dramatic reduction of walking speed and step length without the loss of general leg coordination during locomotion. Genetically restricting the knockdown to the adult stage and subsets of motoneurons yields qualitatively identical results. Taken together, these findings identify GABAergic premotor inhibition of motoneurons as an important determinant of correctly coordinated leg movements and speed of walking in freely behaving Drosophila . Copyright © 2018 the Author(s). Published by PNAS.

Electromyographic Analysis of Single-Leg, Closed Chain Exercises: Implications for Rehabilitation After Anterior Cruciate Ligament Reconstruction

PubMed Central

Beutler, Anthony I.; Cooper, Leslie W.; Kirkendall, Don T.; Garrett, William E.

2002-01-01

Objective: Many knee rehabilitation studies have examined open and closed kinetic chain exercises. However, most studies focus on 2-legged, closed chain exercise. The purpose of our study was to characterize 1-legged, closed chain exercise in young, healthy subjects. Subjects: Eighteen normal subjects (11 men, 7 women; age, 24.6 ± 1.6 years) performed unsupported, 1-legged squats and step-ups to approximately tibial height. Measurements: Knee angle data and surface electromyographic activity from the thigh muscles were recorded. Results: The maximum angle of knee flexion was 111 ± 23° for squats and 101 ± 16° for step-ups. The peak quadriceps activation was 201 ± 66% maximum voluntary isometric contraction, occurring at an angle of 96 ± 16° for squats. Peak quadriceps activation was 207 ± 50% maximum voluntary isometric contraction and occurred at 83 ± 12° for step-ups. Conclusions: The high and sustained levels of quadriceps activation indicate that 1-legged squats and step-ups would be effective in muscle rehabilitation. As functional, closed chain activities, they may also be protective of anterior cruciate ligament grafts. Because these exercises involve no weights or training equipment, they may prove more cost effective than traditional modes of rehabilitation. PMID:12937438

Dynamic leg length asymmetry during gait is not a valid method for estimating mild anatomic leg length discrepancy.

PubMed

Leporace, Gustavo; Batista, Luiz Alberto; Serra Cruz, Raphael; Zeitoune, Gabriel; Cavalin, Gabriel Armondi; Metsavaht, Leonardo

2018-03-01

The purpose of this study was to test the validity of dynamic leg length discrepancy (DLLD) during gait as a radiation-free screening method for measuring anatomic leg length discrepancy (ALLD). Thirty-three subjects with mild leg length discrepancy walked along a walkway and the dynamic leg length discrepancy (DLLD) was calculated using a motion analysis system. Pearson correlation and paired Student t -tests were applied to calculate the correlation and compare the differences between DLLD and ALLD (α = 0.05). The results of our study showed DLLD is not a valid method to predict ALLD in subjects with mild limb discrepancy.

Leg stiffness and stride frequency in human running.

PubMed

Farley, C T; González, O

1996-02-01

When humans and other mammals run, the body's complex system of muscle, tendon and ligament springs behaves like a single linear spring ('leg spring'). A simple spring-mass model, consisting of a single linear leg spring and a mass equivalent to the animal's mass, has been shown to describe the mechanics of running remarkably well. Force platform measurements from running animals, including humans, have shown that the stiffness of the leg spring remains nearly the same at all speeds and that the spring-mass system is adjusted for higher speeds by increasing the angle swept by the leg spring. The goal of the present study is to determine the relative importance of changes to the leg spring stiffness and the angle swept by the leg spring when humans alter their stride frequency at a given running speed. Human subjects ran on treadmill-mounted force platform at 2.5ms-1 while using a range of stride frequencies from 26% below to 36% above the preferred stride frequency. Force platform measurements revealed that the stiffness of the leg spring increased by 2.3-fold from 7.0 to 16.3 kNm-1 between the lowest and highest stride frequencies. The angle swept by the leg spring decreased at higher stride frequencies, partially offsetting the effect of the increased leg spring stiffness on the mechanical behavior of the spring-mass system. We conclude that the most important adjustment to the body's spring system to accommodate higher stride frequencies is that leg spring becomes stiffer.

Protection against high intravascular pressure in giraffe legs.

PubMed

Petersen, Karin K; Hørlyck, Arne; Ostergaard, Kristine H; Andresen, Joergen; Broegger, Torbjoern; Skovgaard, Nini; Telinius, Niklas; Laher, Ismael; Bertelsen, Mads F; Grøndahl, Carsten; Smerup, Morten; Secher, Niels H; Brøndum, Emil; Hasenkam, John M; Wang, Tobias; Baandrup, Ulrik; Aalkjaer, Christian

2013-11-01

The high blood pressure in giraffe leg arteries renders giraffes vulnerable to edema. We investigated in 11 giraffes whether large and small arteries in the legs and the tight fascia protect leg capillaries. Ultrasound imaging of foreleg arteries in anesthetized giraffes and ex vivo examination revealed abrupt thickening of the arterial wall and a reduction of its internal diameter just below the elbow. At and distal to this narrowing, the artery constricted spontaneously and in response to norepinephrine and intravascular pressure recordings revealed a dynamic, viscous pressure drop along the artery. Histology of the isolated median artery confirmed dense sympathetic innervation at the narrowing. Structure and contractility of small arteries from muscular beds in the leg and neck were compared. The arteries from the legs demonstrated an increased media thickness-to-lumen diameter ratio, increased media volume, and increased numbers of smooth muscle cells per segment length and furthermore, they contracted more strongly than arteries from the neck (500 ± 49 vs. 318 ± 43 mmHg; n = 6 legs and neck, respectively). Finally, the transient increase in interstitial fluid pressure following injection of saline was 5.5 ± 1.7 times larger (n = 8) in the leg than in the neck. We conclude that 1) tissue compliance in the legs is low; 2) large arteries of the legs function as resistance arteries; and 3) structural adaptation of small muscle arteries allows them to develop an extraordinary tension. All three findings can contribute to protection of the capillaries in giraffe legs from a high arterial pressure.

The prefrontal oxygenation and ventilatory responses at start of one-legged cycling exercise have relation to central command.

PubMed

Asahara, Ryota; Matsukawa, Kanji; Ishii, Kei; Liang, Nan; Endo, Kana

2016-11-01

When performing exercise arbitrarily, activation of central command should start before the onset of exercise, but when exercise is forced to start with cue, activation of central command should be delayed. We examined whether the in-advance activation of central command influenced the ventilatory response and reflected in the prefrontal oxygenation, by comparing the responses during exercise with arbitrary and cued start. The breath-by-breath respiratory variables and the prefrontal oxygenated-hemoglobin concentration (Oxy-Hb) were measured during one-legged cycling. Minute ventilation (V̇e) at the onset of arbitrary one-legged cycling was augmented to a greater extent than cued cycling, while end-tidal carbon dioxide tension (ETco 2 ) decreased irrespective of arbitrary or cued start. Symmetric increase in the bilateral prefrontal Oxy-Hb occurred before and at the onset of arbitrary one-legged cycling, whereas such an increase was absent with cued start. The time course and magnitude of the increased prefrontal oxygenation were not influenced by the extent of subjective rating of perceived exertion and were the same as those of the prefrontal oxygenation during two-legged cycling previously reported. Mental imagery or passive performance of the one-legged cycling increased V̇e and decreased ETco 2 Neither intervention, however, augmented the prefrontal Oxy-Hb. The changes in ETco 2 could not explain the prefrontal oxygenation response during voluntary or passive one-legged cycling. Taken together, it is likely that the in-advance activation of central command influenced the ventilatory response by enhancing minute ventilation at the onset of one-legged cycling exercise and reflected in the preexercise increase in the prefrontal oxygenation. Copyright © 2016 the American Physiological Society.

Association between leg strength and muscle cross-sectional area of the quadriceps femoris with the physical activity level in octogenarians.

PubMed

Latorre-Román, Pedro Á; Arévalo-Arévalo, Juan Manuel; García-Pinillos, Felipe

2016-06-03

Aging is a complex physiological process whose main feature is the progressive loss of functionality, which may be delayed or attenuated by improving physical fitness.  To determine the association between leg strength and the muscle cross-sectional area of the quadriceps femoris in relation to physical activity level in the elderly.  Thirty-two functionally autonomous people over 80 years (men: 82.80±2.09 years; women: 83.77±4.09 years) participated in this study. The Barthel Index, the Yale Physical Activity Survey and the Chair Stand Test were the instruments used.  There were significant differences between sexes in muscle area (p<0.001) in the Chair Stand Test (p=0.028) and the walk index (p=0.029), with higher values in men. The muscle area and the Chair Stand Test correlated significantly with the walk index (r=0.445, p<0.005, and r=0.522, p<0.001, respectively) and the total weekly activity index (r=0.430, p<0.005, and r=0.519, p<0.001, respectively). In the multiple linear regression models for the total weekly activity index, muscle area and the Chair Stand Test, only the latter behaved as a predictor variable.  Muscle strength and muscle mass of quadriceps showed a significant association with the physical activity level in older people. Leg muscle strength was useful to reveal muscle mass and physical activity level in older people, which is relevant as a clinical practice indicator.

Influence of DARPP-32 genetic variation on BOLD activation to happy faces.

PubMed

Persson, Ninni; Lavebratt, Catarina; Ebner, Natalie C; Fischer, Håkan

2017-10-01

Dopaminergic pathways play a crucial role in reward processing, and advanced age can modulate its efficiency. DARPP-32 controls dopaminergic function and is a chemical nexus of reward processing. In 61 younger (20-30 years) and older adults (54% ♀) (65-74 years), we examined how blood-oxygen-level dependent (BOLD) activation to emotional faces, vary over genotypes at three single nucleotide polymorphism (SNPs), coding for DARPP-32 (rs879606; rs907094; 3764352). We also assessed age-magnification of DARPP-32 effects on BOLD activation. We found that major homozygote G, T or A genotypes, with higher cortical expression of DARPP-32, higher dopamine receptor efficacy, and greater bias toward positive cues, had increased functional connectivity in cortical-subcortical circuits in response to happy faces, engaging the dorsal prefrontal cortex (DLPFC), fusiform gyrus (FG) and the midbrain (MB). Local BOLD response to happy faces in FG, and MB was age-dependent, so that older carriers of the major G, T or A alleles showed lesser activation than minor genotypes. These genetic variants of DARPP-32 did not modulate BOLD response to angry faces, or engagement of the inferior occipital gyrus, to happy or angry faces. Taken together our results lend support for a potential role of DARPP-32 genetic variants in neural response to potential reward triggering cues. © The Author (2017). Published by Oxford University Press.

Dissociable patterns of medial prefrontal and amygdala activity to face identity versus emotion in bipolar disorder.

PubMed

Keener, M T; Fournier, J C; Mullin, B C; Kronhaus, D; Perlman, S B; LaBarbara, E; Almeida, J C; Phillips, M L

2012-09-01

Individuals with bipolar disorder demonstrate abnormal social function. Neuroimaging studies in bipolar disorder have shown functional abnormalities in neural circuitry supporting face emotion processing, but have not examined face identity processing, a key component of social function. We aimed to elucidate functional abnormalities in neural circuitry supporting face emotion and face identity processing in bipolar disorder. Twenty-seven individuals with bipolar disorder I currently euthymic and 27 healthy controls participated in an implicit face processing, block-design paradigm. Participants labeled color flashes that were superimposed on dynamically changing background faces comprising morphs either from neutral to prototypical emotion (happy, sad, angry and fearful) or from one identity to another identity depicting a neutral face. Whole-brain and amygdala region-of-interest (ROI) activities were compared between groups. There was no significant between-group difference looking across both emerging face emotion and identity. During processing of all emerging emotions, euthymic individuals with bipolar disorder showed significantly greater amygdala activity. During facial identity and also happy face processing, euthymic individuals with bipolar disorder showed significantly greater amygdala and medial prefrontal cortical activity compared with controls. This is the first study to examine neural circuitry supporting face identity and face emotion processing in bipolar disorder. Our findings of abnormally elevated activity in amygdala and medial prefrontal cortex (mPFC) during face identity and happy face emotion processing suggest functional abnormalities in key regions previously implicated in social processing. This may be of future importance toward examining the abnormal self-related processing, grandiosity and social dysfunction seen in bipolar disorder.

Seeing faces is necessary for face-patch formation

PubMed Central

Arcaro, Michael J.; Schade, Peter F.; Vincent, Justin L.; Ponce, Carlos R.; Livingstone, Margaret S.

2017-01-01

Here we report that monkeys raised without exposure to faces did not develop face patches, but did develop domains for other categories, and did show normal retinotopic organization, indicating that early face deprivation leads to a highly selective cortical processing deficit. Therefore experience must be necessary for the formation, or maintenance, of face domains. Gaze tracking revealed that control monkeys looked preferentially at faces, even at ages prior to the emergence of face patches, but face-deprived monkeys did not, indicating that face looking is not innate. A retinotopic organization is present throughout the visual system at birth, so selective early viewing behavior could bias category-specific visual responses towards particular retinotopic representations, thereby leading to domain formation in stereotyped locations in IT, without requiring category-specific templates or biases. Thus we propose that environmental importance influences viewing behavior, viewing behavior drives neuronal activity, and neuronal activity sculpts domain formation. PMID:28869581

A new leg voxel model in two different positions for simulation of the non-uniform distribution of (241)Am in leg bones.

PubMed

Khalaf, Majid; Brey, Richard R; Meldrum, Jeff

2013-01-01

A new leg voxel model in two different positions (straight and bent) has been developed for in vivo measurement calibration purposes. This voxel phantom is a representation of a human leg that may provide a substantial enhancement to Monte Carlo modeling because it more accurately models different geometric leg positions and the non-uniform distribution of Am throughout the leg bones instead of assuming a one-position geometry and a uniform distribution of radionuclides. This was accomplished by performing a radiochemical analysis on small sections of the leg bones from the U.S. Transuranium and Uranium Registries (USTUR) case 0846. USTUR case 0846 represents an individual who was repeatedly contaminated by Am via chronic inhalation. To construct the voxel model, high resolution (2 mm) computed tomography (CT) images of the USTUR case 0846 leg were obtained in different positions. Thirty-six (36) objects (universes) were segmented manually from the CT images using 3D-Doctor software. Bones were divided into 30 small sections with an assigned weight exactly equal to the weight of bone sections obtained from radiochemical analysis of the USTUR case 0846 leg. The segmented images were then converted into a boundary file, and the Human Monitoring Laboratory (HML) voxelizer was used to convert the boundary file into the leg voxel phantom. Excluding the surrounding air regions, the straight leg phantom consists of 592,023 voxels, while the bent leg consists of 337,567 voxels. The resulting leg voxel model is now ready for use as an MCNPX input file to simulate in vivo measurement of bone-seeking radionuclides.

Sensorimotor state of the contralateral leg affects ipsilateral muscle coordination of pedaling.

PubMed

Ting, L H; Raasch, C C; Brown, D A; Kautz, S A; Zajac, F E

1998-09-01

, subjects still showed a 33% decrease in negative torque during flexion. These results are consistent with the existence of an inhibitory pathway from elements controlling extension onto contralateral flexion elements, with the pathway operating during two-legged pedaling but not during one-legged pedaling, in which case flexor activity increases. However, this centrally mediated coupling can be overcome with practice, as the human "motor" was able to effectively match the bilateral crank torque after a longer practice regimen. We conclude that the sensorimotor control of a unipedal task is affected by interlimb neural pathways. Thus a task performed unilaterally is not performed with the same muscle coordination utilized in a bipedal condition, even if such coordination would be equally effective in the execution of the unilateral task.

The control of mono-articular muscles in multijoint leg extensions in man.

PubMed Central

van Ingen Schenau, G J; Dorssers, W M; Welter, T G; Beelen, A; de Groot, G; Jacobs, R

1995-01-01

1. Movements often require control of direction and a magnitude of force exerted externally on the environment. Bi-articular upper leg muscles appear to play a unique role in the regulation of the net torques about the hip and knee joints, necessary for the control of this external force. 2. The aim of this study was to test the hypothesis that the mono-articular muscles act as work generators in powerful dynamic leg extensions, which means that they should be activated primarily in the phases during which they can contribute to work, irrespective of the net joint torques required to control the external force. 3. Cycling movements of six trained subjects were analysed by means of inverse dynamics, yielding net joint torques as well as activity patterns and shortening velocities of four mono- and four bi-articular leg muscles. 4. The results show that the mono-articular muscles exert force only in the phase in which these muscles shorten, whereas this appears not to be the case for the bi-articular muscles. 5. Reciprocal patterns of activation of the rectus femoris and hamstring muscles appear to tune the distribution of net joint torques about the hip and knee joints, necessary to control the (changing) direction of the force on the pedal. 6. An analysis of running in man and additional related literature based on animal studies appears to provide further support for the hypothesis that mono- and bi-articular muscles have essentially different roles in these powerful multijoint leg extension tasks. PMID:7602524

Amygdala and whole-brain activity to emotional faces distinguishes major depressive disorder and bipolar disorder.

PubMed

Fournier, Jay C; Keener, Matthew T; Almeida, Jorge; Kronhaus, Dina M; Phillips, Mary L

2013-11-01

It can be clinically difficult to distinguish depressed individuals with bipolar disorder (BD) and major depressive disorder (MDD). To examine potential biomarkers of difference between the two disorders, the current study examined differences in the functioning of emotion-processing neural regions during a dynamic emotional faces task. During functional magnetic resonance imaging, healthy control adults (HC) (n = 29) and depressed adults with MDD (n = 30) and BD (n = 22) performed an implicit emotional-faces task in which they identified a color label superimposed on neutral faces that dynamically morphed into one of four emotional faces (angry, fearful, sad, happy). We compared neural activation between the groups in an amygdala region-of-interest and at the whole-brain level. Adults with MDD showed significantly greater activity than adults with BD in the left amygdala to the anger condition (p = 0.01). Results of whole-brain analyses (at p < 0.005, k ≥ 20) revealed that adults with BD showed greater activity to sad faces in temporoparietal regions, primarily in the left hemisphere, whereas individuals with MDD demonstrated greater activity than those with BD to displays of anger, fear, and happiness. Many of the observed BD-MDD differences represented abnormalities in functioning compared to HC. We observed a dissociation between depressed adults with BD and MDD in the processing of emerging emotional faces. Those with BD showed greater activity during mood-congruent (i.e., sad) faces, whereas those with MDD showed greater activity for mood-incongruent (i.e., fear, anger, and happy) faces. Such findings may reflect markers of differences between BD and MDD depression in underlying pathophysiological processes. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Ocean Drilling Program: Completed Legs

Science.gov Websites

. Austin Leg summary Repository Wolfgang Schlager 102 14-Mar-85 25-Apr-85 Miami, Florida 418 Bermuda Rise Lisbon, Portugal 902-906 New Jersey Sea-Level Transect Peter Blum Gregory Mountain Leg summary Repository , Nova Scotia 1071-1073 Continuing the New Jersey Sea-Level Transect Mitchell J. Malone James A. Austin

RELAP5 Analyses of OECD/NEA ROSA-2 Project Experiments on Intermediate-Break LOCAs at Hot Leg or Cold Leg

NASA Astrophysics Data System (ADS)

Takeda, Takeshi; Maruyama, Yu; Watanabe, Tadashi; Nakamura, Hideo

Experiments simulating PWR intermediate-break loss-of-coolant accidents (IBLOCAs) with 17% break at hot leg or cold leg were conducted in OECD/NEA ROSA-2 Project using the Large Scale Test Facility (LSTF). In the hot leg IBLOCA test, core uncovery started simultaneously with liquid level drop in crossover leg downflow-side before loop seal clearing (LSC) induced by steam condensation on accumulator coolant injected into cold leg. Water remained on upper core plate in upper plenum due to counter-current flow limiting (CCFL) because of significant upward steam flow from the core. In the cold leg IBLOCA test, core dryout took place due to rapid liquid level drop in the core before LSC. Liquid was accumulated in upper plenum, steam generator (SG) U-tube upflow-side and SG inlet plenum before the LSC due to CCFL by high velocity vapor flow, causing enhanced decrease in the core liquid level. The RELAP5/MOD3.2.1.2 post-test analyses of the two LSTF experiments were performed employing critical flow model in the code with a discharge coefficient of 1.0. In the hot leg IBLOCA case, cladding surface temperature of simulated fuel rods was underpredicted due to overprediction of core liquid level after the core uncovery. In the cold leg IBLOCA case, the cladding surface temperature was underpredicted too due to later core uncovery than in the experiment. These may suggest that the code has remaining problems in proper prediction of primary coolant distribution.

Individual differences in symptom severity and behavior predict neural activation during face processing in adolescents with autism

PubMed Central

Scherf, K. Suzanne; Elbich, Daniel; Minshew, Nancy; Behrmann, Marlene

2014-01-01

Despite the impressive literature describing atypical neural activation in visuoperceptual face processing regions in autism, almost nothing is known about whether these perturbations extend to more affective regions in the circuitry and whether they bear any relationship to symptom severity or atypical behavior. Using fMRI, we compared face-, object-, and house-related activation in adolescent males with high-functioning autism (HFA) and typically developing (TD) matched controls. HFA adolescents exhibited hypo-activation throughout the core visuoperceptual regions, particularly in the right hemisphere, as well as in some of the affective/motivational face-processing regions, including the posterior cingulate cortex and right anterior temporal lobe. Conclusions about the relative hyper- or hypo-activation of the amygdala depended on the nature of the contrast that was used to define the activation. Individual differences in symptom severity predicted the magnitude of face activation, particularly in the right fusiform gyrus. Also, among the HFA adolescents, face recognition performance predicted the magnitude of face activation in the right anterior temporal lobe, a region that supports face individuation in TD adults. Our findings reveal a systematic relation between the magnitude of neural dysfunction, severity of autism symptoms, and variation in face recognition behavior in adolescents with autism. In so doing, we uncover brain–behavior relations that underlie one of the most prominent social deficits in autism and help resolve discrepancies in the literature. PMID:25610767

Grounded running in quails: simulations indicate benefits of observed fixed aperture angle between legs before touch-down.

PubMed

Andrada, Emanuel; Rode, Christian; Blickhan, Reinhard

2013-10-21

Many birds use grounded running (running without aerial phases) in a wide range of speeds. Contrary to walking and running, numerical investigations of this gait based on the BSLIP (bipedal spring loaded inverted pendulum) template are rare. To obtain template related parameters of quails (e.g. leg stiffness) we used x-ray cinematography combined with ground reaction force measurements of quail grounded running. Interestingly, with speed the quails did not adjust the swing leg's angle of attack with respect to the ground but adapted the angle between legs (which we termed aperture angle), and fixed it about 30ms before touchdown. In simulations with the BSLIP we compared this swing leg alignment policy with the fixed angle of attack with respect to the ground typically used in the literature. We found symmetric periodic grounded running in a simply connected subset comprising one third of the investigated parameter space. The fixed aperture angle strategy revealed improved local stability and surprising tolerance with respect to large perturbations. Starting with the periodic solutions, after step-down step-up or step-up step-down perturbations of 10% leg rest length, in the vast majority of cases the bipedal SLIP could accomplish at least 50 steps to fall. The fixed angle of attack strategy was not feasible. We propose that, in small animals in particular, grounded running may be a common gait that allows highly compliant systems to exploit energy storage without the necessity of quick changes in the locomotor program when facing perturbations. © 2013 Elsevier Ltd. All rights reserved.

Test-to-test variability in motor activity during the suggested immobilization test in restless legs patients.

PubMed

Haba-Rubio, José; Sforza, Emilia

2006-10-01

To evaluate the test-to-test variability of the suggested immobilization test (SIT) in patients with restless legs syndrome (RLS). Twenty patients with primary RLS (12 men and eight women; age: 53.3+/-11.3 years) were selected for the study. We compared the results of two SITs performed on two consecutive evenings prior to polysomnographic recordings. Overall, the periodic leg movement index during the SIT (SIT PLM) and the SIT PLM index associated with sensory manifestations (SIT PLM+) were not significantly different between tests. The number of PLM sequences per SIT, the mean PLM duration and the PLM interval did not significantly change between the two consecutive tests. The pattern of temporal evolution of motor activity across the SIT was very reproducible, SIT PLM showing a clear tendency to a progressive increase across the test, with the SIT PLM+ index decreasing in the second half of the test. Despite good reproducibility, there were marked intra-individual differences. Considering the proposed cut-off value of 12 for the SIT PLM index to confirm RLS, 11 patients were positive at the first test and four additional patients became positive at the second test. SIT PLM index changes did not correlate with age, severity of disease and polysomnographic measures. Quantitative analysis of motor activity during two consecutive SITs in RLS patients showed a significant inter-test intra-individual variability unrelated to demographic, clinical or polysomnographic parameters. SIT PLM index variability suggests that a single test would not be sensitive enough for diagnostic purposes in unclear cases and that new criteria need to be applied to increase its specificity and sensitivity.

THE RELATIONSHIP BETWEEN VARIOUS MODES OF SINGLE LEG POSTURAL CONTROL ASSESSMENT

PubMed Central

Schmitz, Randy

2012-01-01

Purpose/Background: While various techniques have been developed to assess the postural control system, little is known about the relationship between single leg static and functional balance. The purpose of the current study was to determine the relationship between the performance measures of several single leg postural stability tests. Methods: Forty six recreationally active college students (17 males, 29 females, 21±3 yrs, 173±10 cm) performed six single leg tests in a counterbalanced order: 1) Firm Surface-Eyes Open, 2) Firm Surface-Eyes Closed, 3) Multiaxial Surface-Eyes Open, 4) Multiaxial Surface-Eyes Closed, 5) Star Excursion Balance Test (posterior medial reach), 6) Single leg Hop-Stabilization Test. Bivariate correlations were conducted between the six outcome variables. Results: Mild to moderate correlations existed between the static tests. No significant correlations existed involving either of the functional tests. Conclusions: The results indicate that while performance of static balance tasks are mildly to moderately related, they appear to be unrelated to functional reaching or hopping movements, supporting the utilization of a battery of tests to determine overall postural control performance. Level of Evidence: 3b PMID:22666640

Bed rest attenuates sympathetic and pressor responses to isometric exercise in antigravity leg muscles in humans.

PubMed

Kamiya, Atsunori; Michikami, Daisaku; Shiozawa, Tomoki; Iwase, Satoshi; Hayano, Junichiro; Kawada, Toru; Sunagawa, Kenji; Mano, Tadaaki

2004-05-01

Although spaceflight and bed rest are known to cause muscular atrophy in the antigravity muscles of the legs, the changes in sympathetic and cardiovascular responses to exercises using the atrophied muscles remain unknown. We hypothesized that bed rest would augment sympathetic responses to isometric exercise using antigravity leg muscles in humans. Ten healthy male volunteers were subjected to 14-day 6 degrees head-down bed rest. Before and after bed rest, they performed isometric exercises using leg (plantar flexion) and forearm (handgrip) muscles, followed by 2-min postexercise muscle ischemia (PEMI) that continues to stimulate the muscle metaboreflex. These exercises were sustained to fatigue. We measured muscle sympathetic nerve activity (MSNA) in the contralateral resting leg by microneurography. In both pre- and post-bed-rest exercise tests, exercise intensities were set at 30 and 70% of the maximum voluntary force measured before bed rest. Bed rest attenuated the increase in MSNA in response to fatiguing plantar flexion by approximately 70% at both exercise intensities (both P < 0.05 vs. before bed rest) and reduced the maximal voluntary force of plantar flexion by 15%. In contrast, bed rest did not alter the increase in MSNA response to fatiguing handgrip and had no effects on the maximal voluntary force of handgrip. Although PEMI sustained MSNA activation before bed rest in all trials, bed rest entirely eliminated the PEMI-induced increase in MSNA in leg exercises but partially attenuated it in forearm exercises. These results do not support our hypothesis but indicate that bed rest causes a reduction in isometric exercise-induced sympathetic activation in (probably atrophied) antigravity leg muscles.

Soccer players have a better standing balance in nondominant one-legged stance

PubMed Central

Barone, Rosario; Macaluso, Filippo; Traina, Marcello; Leonardi, Vincenza; Farina, Felicia; Di Felice, Valentina

2011-01-01

The purpose of this study was to analyze the differences in standing balance during dominant and nondominant one-legged stance among athletes of different sports and sedentary subjects. The right-footed subjects of four groups (sedentary, n = 20; soccer, n = 20; basketball, n = 20; windsurfer n = 20) underwent 5-sec unipedal (left and right foot) stabilometric analysis with open eyes and closed eyes to measure center of pressure (COP) sway path and COP velocity (mean value, anteroposterior, and laterolateral in millimeters per second). The soccer group showed better standing balance on the left leg than the sedentary group (P < 0.05). No other significant differences were observed within and amongst groups. The soccer players have a better standing balance on the nondominant leg because of soccer activity. PMID:24198563

Loading and performance of the support leg in kicking.

PubMed

Ball, Kevin

2013-09-01

The punt kick is important in many football codes and support leg kinematics and ground reaction forces have been implicated in injury and performance in kicking. To evaluate ground reaction forces and support leg kinematics in the punt kick. Cross sectional study. Seven elite Australian football players performed maximal kicks into a net using both the preferred and non-preferred legs. A force plate measured ground reaction forces and an optical motion capture system (200Hz) collected kinematic data during the stance phase of the kick. Preferred and non-preferred legs were compared and performance was evaluated by correlating parameters with foot speed at ball contact. Vertical forces were larger than running at a similar speed but did not reach levels that might be considered an injury risk. Braking forces were directed solely posteriorly, as for soccer kicks, but lateral force patterns varied with some players experiencing greater forces medially and others laterally. A more extended support leg, larger peak vertical and braking force during the stance phase and a shorter stance contact time was associated with larger kick leg foot speed at ball contact. No difference existed between the preferred and non-preferred legs for ground reaction forces or support leg mechanics. To punt kick longer, a straighter support leg, less time on the ground and stronger braking should be encouraged. Conditioning the support leg to provide stronger braking potential is recommended. Copyright © 2012 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Towards a Comparative Measure of Legged Agility

DTIC Science & Technology

2014-06-01

body movement with change of velocity or direction in response to a stimulus” [18]. Notwithstanding the many informative and inspiring studies of legged...specific power (watts per kilogram taken over a gait cycle of leg power output relative to leg muscle mass or body mass) [22, 26–28] but it is not scale...closest to the body mass normalized mea- sure we will introduce below. In contrast, characterizing directional aspects of agility performance seems

A Comparison of the Effectiveness of a Game Informed Online Learning Activity and Face to Face Teaching in Increasing Knowledge about Managing Aggression in Health Settings

ERIC Educational Resources Information Center

McKenzie, Karen

2013-01-01

The present study compared the impact of face to face teaching with a short online game informed learning activity on health participants' knowledge about, and confidence in, managing aggressive situations. Both forms of teaching resulted in a significant increase in participants' knowledge and confidence. Face to face training led to…

A Face Inversion Effect without a Face

ERIC Educational Resources Information Center

Brandman, Talia; Yovel, Galit

2012-01-01

Numerous studies have attributed the face inversion effect (FIE) to configural processing of internal facial features in upright but not inverted faces. Recent findings suggest that face mechanisms can be activated by faceless stimuli presented in the context of a body. Here we asked whether faceless stimuli with or without body context may induce…

Motion of the center of mass in children with spastic hemiplegia: balance, energy transfer, and work performed by the affected leg vs. the unaffected leg.

PubMed

Feng, Jing; Pierce, Rosemary; Do, K Patrick; Aiona, Michael

2014-01-01

Asymmetry between limbs in people with spastic hemiplegic cerebral palsy (HEMI) adversely affects limb coordination and energy generation and consumption. This study compared how the affected leg and the unaffected leg of children with HEMI would differ based on which leg trails. Full-body gait analysis data and force-plate data were analyzed for 31 children (11.9 ± 3.8 years) with HEMI and 23 children (11.1 ± 3.1 years) with typical development (TD). Results showed that peak posterior center of mass-center of pressure (COM-COP) inclination angles of HEMI were smaller than TD when the affected leg trailed but not when the unaffected leg trailed. HEMI showed greater peak medial COM-COP inclination angles and wider step width than TD, no matter which leg trailed. More importantly, when the affected leg of HEMI trailed, it did not perform enough positive work during double support to propel COM motion. Consequently, the unaffected leg had to perform additional positive work during the early portion of single support, which costs more energy. When the unaffected leg trailed, the affected leg performed more negative work during double support; therefore, more positive work was still needed during early single support, but energy efficiency was closer to that of TD. Energy recovery factor was lower when the affected leg trailed than when the unaffected leg trailed; both were lower than TD. These findings suggest that the trailing leg plays a significant role in propelling COM motion during double support, and the 'unaffected' side of HEMI may not be completely unaffected. It is important to strengthen both legs. Copyright © 2013 Elsevier B.V. All rights reserved.

Decreased Hip, Lower Leg, and Humeral Fractures but Increased Forearm Fractures in Highly Active Individuals.

PubMed

Stattin, Karl; Hållmarker, Ulf; Ärnlöv, Johan; James, Stefan; Michaëlsson, Karl; Byberg, Liisa

2018-06-22

It is not known how physical exercise affects the risk of different types of fractures, especially in highly active individuals. To investigate this association, we studied a cohort of 118,204 men and 71,757 women who from 1991 to 2009 participated in Vasaloppet, a long-distance cross-country skiing race in Sweden, and 505,194 nonparticipants frequency-matched on sex, age, and county of residence from the Swedish population. Participants ranged from recreational exercisers to world-class skiers. Race participation, distance of race run, number of races participated in, and finishing time were used as proxies for physical exercise. Incident fractures from 1991 to 2010 were obtained from national Swedish registers. Over a median follow-up of 8.9 years, 53,175 fractures of any type, 2929 hip, 3107 proximal humerus, 11,875 lower leg, 11,733 forearm, and 2391 vertebral fractures occurred. In a Cox proportional hazard regression analysis using time-updated exposure and covariate information, participation in the race was associated with an increased risk of any type of fracture (hazard ratio [HR], 1.02; 95% CI, 1.00 to 1.05); forearm fractures had an HR, 1.11 with a 95% CI, 1.06 to 1.15. There was a lower risk of hip (HR, 0.75; 95% CI, 0.67 to 0.83), proximal humerus (HR, 0.90; 95% CI, 0.82 to 0.98), and lower leg fractures (HR, 0.93; 95% CI, 0.89 to 0.97), whereas the HR of vertebral fracture was 0.97 with a 95% CI, 0.88 to 1.07. Among participants, the risk of fracture was similar irrespective of race distance and number of races run. Participants close to the median finishing time had a lower risk of fracture compared with faster and slower participants. In summary, high levels of physical exercise were associated with a slightly higher risk of fractures of any type, including forearm fractures, but a lower risk of hip, proximal humerus, and lower leg fractures. © 2018 American Society for Bone and Mineral Research. © 2018 American Society for Bone and Mineral

Chronic Lower Leg Pain in Athletes

PubMed Central

Brewer, Rachel Biber; Gregory, Andrew J. M.

2012-01-01

Context: Chronic lower leg pain in athletes can be a frustrating problem for patients and a difficult diagnosis for clinicians. Myriad approaches have been suggested to evaluate these conditions. With the continued evolution of diagnostic studies, evidence-based guidance for a standard approach is unfortunately sparse. Evidence Acquisition: PubMed was searched from January 1980 to May 2011 to identify publications regarding chronic lower leg pain in athletes (excluding conditions related to the foot), including differential diagnosis, clinical presentation, physical examination, history, diagnostic workup, and treatment. Results: Leg pain in athletes can be caused by many conditions, with the most frequent being medial tibial stress syndrome; chronic exertional compartment syndrome, stress fracture, nerve entrapment, and popliteal artery entrapment syndrome are also considerations. Conservative management is the mainstay of care for the majority of causes of chronic lower leg pain; however, surgical intervention may be necessary. Conclusion: Chronic lower extremity pain in athletes includes a wide differential and can pose diagnostic dilemmas for clinicians. PMID:23016078

Human hopping on damped surfaces: strategies for adjusting leg mechanics.

PubMed

Moritz, Chet T; Farley, Claire T

2003-08-22

Fast-moving legged animals bounce along the ground with spring-like legs and agilely traverse variable terrain. Previous research has shown that hopping and running humans maintain the same bouncing movement of the body's centre of mass on a range of elastic surfaces by adjusting their spring-like legs to exactly offset changes in surface stiffness. This study investigated human hopping on damped surfaces that dissipated up to 72% of the hopper's mechanical energy. On these surfaces, the legs did not act like pure springs. Leg muscles performed up to 24-fold more net work to replace the energy lost by the damped surface. However, considering the leg and surface together, the combination appeared to behave like a constant stiffness spring on all damped surfaces. By conserving the mechanics of the leg-surface combination regardless of surface damping, hoppers also conserved centre-of-mass motions. Thus, the normal bouncing movements of the centre of mass in hopping are not always a direct result of spring-like leg behaviour. Conserving the trajectory of the centre of mass by maintaining spring-like mechanics of the leg-surface combination may be an important control strategy for fast-legged locomotion on variable terrain.

Prior exercise and standing as strategies to circumvent sitting-induced leg endothelial dysfunction.

PubMed

Morishima, Takuma; Restaino, Robert M; Walsh, Lauren K; Kanaley, Jill A; Padilla, Jaume

2017-06-01

We have previously shown that local heating or leg fidgeting can prevent prolonged sitting-induced leg endothelial dysfunction. However, whether physical activity prevents subsequent sitting-induced leg endothelial dysfunction remains unknown. Herein, we tested the hypothesis that sitting-induced leg endothelial dysfunction would be prevented by prior exercise. We also examined if, in the absence of exercise, standing is an effective alternative strategy to sitting for conserving leg endothelial function. Fifteen young healthy subjects completed three randomized experimental trials: (1) sitting without prior exercise; (2) sitting with prior exercise; and (3) standing without prior exercise. Following baseline popliteal artery flow-mediated dilation (FMD) measurements, subjects maintained a supine position for 45 min in the sitting and standing trials, without prior exercise, or performed 45 min of leg cycling before sitting (i.e. sitting with prior exercise trial). Thereafter, subjects were positioned into a seated or standing position, according to the trial, for 3 h. Popliteal artery FMD measures were then repeated. Three hours of sitting without prior exercise caused a significant impairment in popliteal artery FMD (baseline: 3.8±0.5%, post-sitting: 1.5±0.5%, P <0.05), which was prevented when sitting was preceded by a bout of cycling exercise (baseline: 3.8±0.5%, post-sitting: 3.6±0.7%, P >0.05). Three hours of standing did not significantly alter popliteal artery FMD (baseline: 4.1±0.4%, post-standing: 4.3±0.4%, P >0.05). In conclusion, prolonged sitting-induced leg endothelial dysfunction can be prevented by prior aerobic exercise. In addition, in the absence of exercise, standing represents an effective substitute to sitting for preserving leg conduit artery endothelial function. © 2017 The Author(s). published by Portland Press Limited on behalf of the Biochemical Society.

ODYSSEUS autonomous walking robot: The leg/arm design

NASA Technical Reports Server (NTRS)

Bourbakis, N. G.; Maas, M.; Tascillo, A.; Vandewinckel, C.

1994-01-01

ODYSSEUS is an autonomous walking robot, which makes use of three wheels and three legs for its movement in the free navigation space. More specifically, it makes use of its autonomous wheels to move around in an environment where the surface is smooth and not uneven. However, in the case that there are small height obstacles, stairs, or small height unevenness in the navigation environment, the robot makes use of both wheels and legs to travel efficiently. In this paper we present the detailed hardware design and the simulated behavior of the extended leg/arm part of the robot, since it plays a very significant role in the robot actions (movements, selection of objects, etc.). In particular, the leg/arm consists of three major parts: The first part is a pipe attached to the robot base with a flexible 3-D joint. This pipe has a rotated bar as an extended part, which terminates in a 3-D flexible joint. The second part of the leg/arm is also a pipe similar to the first. The extended bar of the second part ends at a 2-D joint. The last part of the leg/arm is a clip-hand. It is used for selecting several small weight and size objects, and when it is in a 'closed' mode, it is used as a supporting part of the robot leg. The entire leg/arm part is controlled and synchronized by a microcontroller (68CH11) attached to the robot base.

Human hopping on damped surfaces: strategies for adjusting leg mechanics.

PubMed Central

Moritz, Chet T; Farley, Claire T

2003-01-01

Fast-moving legged animals bounce along the ground with spring-like legs and agilely traverse variable terrain. Previous research has shown that hopping and running humans maintain the same bouncing movement of the body's centre of mass on a range of elastic surfaces by adjusting their spring-like legs to exactly offset changes in surface stiffness. This study investigated human hopping on damped surfaces that dissipated up to 72% of the hopper's mechanical energy. On these surfaces, the legs did not act like pure springs. Leg muscles performed up to 24-fold more net work to replace the energy lost by the damped surface. However, considering the leg and surface together, the combination appeared to behave like a constant stiffness spring on all damped surfaces. By conserving the mechanics of the leg-surface combination regardless of surface damping, hoppers also conserved centre-of-mass motions. Thus, the normal bouncing movements of the centre of mass in hopping are not always a direct result of spring-like leg behaviour. Conserving the trajectory of the centre of mass by maintaining spring-like mechanics of the leg-surface combination may be an important control strategy for fast-legged locomotion on variable terrain. PMID:12965003

Recruitment strategy effectiveness for a cryotherapy intervention for a venous leg ulcer prevention study.

PubMed

Kelechi, Teresa J; Watts, Ashlee; Wiseman, Jan

2010-01-01

strategies ($83 vs $215). However, the time spent by the principal investigator (approximately 100 hours or 2.5 hours per week x 40 weeks) on recruitment, particularly maintaining frequent face-to-face contact with providers, increased success in the area of healthcare provider referrals. A variety of recruitment strategies are needed to ensure a diverse participant response to clinical research studies. As nurses become more involved in research activities, and particularly in recruitment, it is important to understand the most effective types of strategies and costs associated with these activities.

Night Leg Cramps

MedlinePlus

... feet or thighs might cramp as well. Forcefully stretching the contracted muscle relieves the pain. Most of ... include Drinking plenty of fluids to avoid dehydration Stretching your leg muscles or riding a stationary bicycle ...

Leg MRI scan

MedlinePlus

... anything that contains metal into the scanner room. Considerations Tests that may be done instead of an ... Magnetic resonance imaging - ankle; MRI - femur; MRI - leg Patient Instructions Femur fracture repair - discharge Hip fracture - discharge ...

Frustrated S = 1/2 Two-Leg Ladder with Different Leg Interactions

NASA Astrophysics Data System (ADS)

Tonegawa, Takashi; Okamoto, Kiyomi; Hikihara, Toshiya; Sakai, Tôru

2017-04-01

We explore the ground-state phase diagram of the S = 1/2 two-leg ladder. The isotropic leg interactions J1,a and J1,b between nearest neighbor spins in the legs a and b, respectively, are different from each other. The xy and z components of the uniform rung interactions are denoted by Jr and ΔJr, respectively, where Δ is the XXZ anisotropy parameter. This system has a frustration when J1,aJ1,b < 0 irrespective of the sign of Jr. The phase diagrams on the Δ (0≤Δ<1) versus J1,b plane in the cases of J1,a = - 0.2 and J1,a = 0.2 with Jr = -1 are determined numerically. We employ the physical consideration, the level spectroscopy analysis of the results obtained by the exact diagonalization method and also the density-matrix renormalization-group method. It is found that the non-collinear ferrimagnetic (NCFR) state appears as the ground state in the frustrated region of the parameters. Furthermore, the direct-product triplet-dimer (TD) state in which all rungs form the TD pair is the exact ground state, when J1,a + J1,b = 0 and 0≤ Δ ≲ 0.83. The obtained phase diagrams consist of the TD, XY and Haldane phases as well as the NCFR phase.

A Biomechanical Comparison of Single-Leg Landing and Unplanned Sidestepping.

PubMed

Chinnasee, Chamnan; Weir, Gillian; Sasimontonkul, Siriporn; Alderson, Jacqueline; Donnelly, Cyril

2018-06-14

Unplanned sidestepping and single-leg landing have both been used to screen athletes for injury risk in sport. The aim of this study was to directly compare the lower limb mechanics of three single-leg landing tasks and an unplanned sidestepping task. Thirteen elite female team sport athletes completed a series of non-contact single-leg drop landings, single-leg countermovement jumps, single-leg jump landings and unplanned sidestepping in a randomized counterbalanced design. Three dimensional kinematics (250 Hz) and ground reaction force (2,000 Hz) data with a participant specific lower limb skeletal model were used to calculate and compare hip, knee and ankle joint kinematics, peak joint moments, instantaneous joint power and joint work during the weight acceptance phase of each sporting task (α=0.05). Peak knee joint moments and relevant injury risk thresholds were used to classify each athlete's anterior cruciate ligament injury risk during unplanned sidestepping and single-leg jump landing. Results showed that peak joint moments, power and work were greater during the single-leg jump landing task when compared to the single-leg drop landings and single-leg countermovement jumps tasks. Peak frontal and sagittal plane knee joint moments, knee joint power, as well as hip and knee joint work were greater during unplanned sidestepping when compared to the landing tasks. Peak ankle joint moments, power and work were greater during the landing tasks when compared to unplanned sidestepping. For 4 of the 13 athletes tested, their anterior cruciate ligament injury risk classification changed depending on whether they performed an unplanned sidestepping or single-leg jump landing testing procedure. To summarize, a single-leg jump landing testing procedure places a larger mechanical on the ankle joint when compared to single-leg drop landings, single-leg countermovement jumps and unplanned sidestepping. An unplanned sidestepping testing procedure places a larger

Gender differences in BOLD activation to face photographs and video vignettes.

PubMed

Fine, Jodene Goldenring; Semrud-Clikeman, Margaret; Zhu, David C

2009-07-19

Few neuroimaging studies have reported gender differences in response to human emotions, and those that have examined such differences have utilized face photographs. This study presented not only human face photographs of positive and negative emotions, but also video vignettes of positive and negative social human interactions in an attempt to provide a more ecologically appropriate stimuli paradigm. Ten male and 10 female healthy right-handed young adults were shown positive and negative affective social human faces and video vignettes to elicit gender differences in social/emotional perception. Conservative ROI (region of interest) analysis indicated greater male than female activation to positive affective photos in the anterior cingulate, medial frontal gyrus, superior frontal gyrus and superior temporal gyrus, all in the right hemisphere. No significant ROI gender differences were observed to negative affective photos. Male greater than female activation was seen in ROIs of the left posterior cingulate and the right inferior temporal gyrus to positive social videos. Male greater than female activation occurred in only the left middle temporal ROI for negative social videos. Consistent with previous findings, males were more lateralized than females. Although more activation was observed overall to video compared to photo conditions, males and females appear to process social video stimuli more similarly to one another than they do for photos. This study is a step forward in understanding the social brain with more ecologically valid stimuli that more closely approximates the demands of real-time social and affective processing.

Sensitivity of sensor-based sit-to-stand peak power to the effects of training leg strength, leg power and balance in older adults.

PubMed

Regterschot, G Ruben H; Folkersma, Marjanne; Zhang, Wei; Baldus, Heribert; Stevens, Martin; Zijlstra, Wiebren

2014-01-01

Increasing leg strength, leg power and overall balance can improve mobility and reduce fall risk. Sensor-based assessment of peak power during the sit-to-stand (STS) transfer may be useful for detecting changes in mobility and fall risk. Therefore, this study investigated whether sensor-based STS peak power and related measures are sensitive to the effects of increasing leg strength, leg power and overall balance in older adults. A further aim was to compare sensitivity between sensor-based STS measures and standard clinical measures of leg strength, leg power, balance, mobility and fall risk, following an exercise-based intervention. To achieve these aims, 26 older adults (age: 70-84 years) participated in an eight-week exercise program aimed at improving leg strength, leg power and balance. Before and after the intervention, performance on normal and fast STS transfers was evaluated with a hybrid motion sensor worn on the hip. In addition, standard clinical tests (isometric quadriceps strength, Timed Up and Go test, Berg Balance Scale) were performed. Standard clinical tests as well as sensor-based measures of peak power, maximal velocity and duration of normal and fast STS showed significant improvements. Sensor-based measurement of peak power, maximal velocity and duration of normal STS demonstrated a higher sensitivity (absolute standardized response mean (SRM): ≥ 0.69) to the effects of training leg strength, leg power and balance than standard clinical measures (absolute SRM: ≤ 0.61). Therefore, the presented sensor-based method appears to be useful for detecting changes in mobility and fall risk. Copyright © 2013 Elsevier B.V. All rights reserved.

Promethus Hot Leg Piping Concept

DOE Office of Scientific and Technical Information (OSTI.GOV)

AM Girbik; PA Dilorenzo

2006-01-24

The Naval Reactors Prime Contractor Team (NRPCT) recommended the development of a gas cooled reactor directly coupled to a Brayton energy conversion system as the Space Nuclear Power Plant (SNPP) for NASA's Project Prometheus. The section of piping between the reactor outlet and turbine inlet, designated as the hot leg piping, required unique design features to allow the use of a nickel superalloy rather than a refractory metal as the pressure boundary. The NRPCT evaluated a variety of hot leg piping concepts for performance relative to SNPP system parameters, manufacturability, material considerations, and comparison to past high temperature gas reactormore » (HTGR) practice. Manufacturability challenges and the impact of pressure drop and turbine entrance temperature reduction on cycle efficiency were discriminators between the piping concepts. This paper summarizes the NRPCT hot leg piping evaluation, presents the concept recommended, and summarizes developmental issues for the recommended concept.« less

Effects of an Online Learning Community on Active and Reflective Learners' Learning Performance and Attitudes in a Face-to-Face Undergraduate Course

ERIC Educational Resources Information Center

Zhan, Zehui; Xu, Fuyin; Ye, Huiwen

2011-01-01

The purpose of this study was to examine the effects of an Online Learning Community (OLC) on active and reflective learners' learning performance and attitude in a face-to-face undergraduate digital design course. 814 freshmen in an introductory digital design course were randomly assigned to one of two treatments: one offered students an OLC,…

Guided Saccades Modulate Face- and Body-Sensitive Activation in the Occipitotemporal Cortex during Social Perception

ERIC Educational Resources Information Center

Morris, James P.; Green, Steven R.; Marion, Brian; McCarthy, Gregory

2008-01-01

Functional magnetic resonance imaging (fMRI) has identified distinct brain regions in ventral occipitotemporal cortex (VOTC) and lateral occipitotemporal cortex (LOTC) that are differentially activated by pictures of faces and bodies. Recent work from our laboratory has shown that the strong LOTC activation evoked by bodies in which the face is…

Altered spontaneous neural activity in the occipital face area reflects behavioral deficits in developmental prosopagnosia.

PubMed

Zhao, Yuanfang; Li, Jingguang; Liu, Xiqin; Song, Yiying; Wang, Ruosi; Yang, Zetian; Liu, Jia

2016-08-01

Individuals with developmental prosopagnosia (DP) exhibit severe difficulties in recognizing faces and to a lesser extent, also exhibit difficulties in recognizing non-face objects. We used fMRI to investigate whether these behavioral deficits could be accounted for by altered spontaneous neural activity. Two aspects of spontaneous neural activity were measured: the intensity of neural activity in a voxel indexed by the fractional amplitude of spontaneous low-frequency fluctuations (fALFF), and the connectivity of a voxel to neighboring voxels indexed by regional homogeneity (ReHo). Compared with normal adults, both the fALFF and ReHo values within the right occipital face area (rOFA) were significantly reduced in DP subjects. Follow-up studies on the normal adults revealed that these two measures indicated further functional division of labor within the rOFA. The fALFF in the rOFA was positively correlated with behavioral performance in recognition of non-face objects, whereas ReHo in the rOFA was positively correlated with processing of faces. When considered together, the altered fALFF and ReHo within the same region (rOFA) may account for the comorbid deficits in both face and object recognition in DPs, whereas the functional division of labor in these two measures helps to explain the relative independency of deficits in face recognition and object recognition in DP. Copyright © 2016 Elsevier Ltd. All rights reserved.

Encouraging Participation in Face-to-Face Lectures: The Index Card Technique

ERIC Educational Resources Information Center

Daws, Laura Beth

2018-01-01

Courses: This activity will work in any face-to-face communication lecture course. Objectives: By the end of the semester in a face-to-face lecture class, every student will have engaged in verbal discussion.

Skipping on uneven ground: trailing leg adjustments simplify control and enhance robustness.

PubMed

Müller, Roy; Andrada, Emanuel

2018-01-01

It is known that humans intentionally choose skipping in special situations, e.g. when descending stairs or when moving in environments with lower gravity than on Earth. Although those situations involve uneven locomotion, the dynamics of human skipping on uneven ground have not yet been addressed. To find the reasons that may motivate this gait, we combined experimental data on humans with numerical simulations on a bipedal spring-loaded inverted pendulum model (BSLIP). To drive the model, the following parameters were estimated from nine subjects skipping across a single drop in ground level: leg lengths at touchdown, leg stiffness of both legs, aperture angle between legs, trailing leg angle at touchdown (leg landing first after flight phase), and trailing leg retraction speed. We found that leg adjustments in humans occur mostly in the trailing leg (low to moderate leg retraction during swing phase, reduced trailing leg stiffness, and flatter trailing leg angle at lowered touchdown). When transferring these leg adjustments to the BSLIP model, the capacity of the model to cope with sudden-drop perturbations increased.

Managing leg ulceration in intravenous drug users.

PubMed

Geraghty, Jemell

2015-09-01

Chronic venous leg ulceration is a long-term condition commonly associated with lower-limb injecting and chronic venous hypertension caused by collapsed veins, incompetent valves, deep vein thrombosis and reflux. It is not usually a medical emergency, but intravenous (IV) drug users with leg ulcers can attend emergency departments (EDs) with a different primary complaint such as pain or because they cannot access local primary care or voluntary services. Leg ulceration might then be identified during history taking, so it is important that ED nurses know how to assess and manage these wounds. This article explains how to assess and manage chronic venous leg ulcers in patients with a history of IV drug use, and highlights the importance of referral to specialist services when required, and to local primary care or voluntary services, before discharge to prevent admission and re-attendance.

Dynamics of underwater legged locomotion: modeling and experiments on an octopus-inspired robot.

PubMed

Calisti, M; Corucci, F; Arienti, A; Laschi, C

2015-07-30

This paper studies underwater legged locomotion (ULL) by means of a robotic octopus-inspired prototype and its associated model. Two different types of propulsive actions are embedded into the robot model: reaction forces due to leg contact with the ground and hydrodynamic forces such as the drag arising from the sculling motion of the legs. Dynamic parameters of the model are estimated by means of evolutionary techniques and subsequently the model is exploited to highlight some distinctive features of ULL. Specifically, the separation between the center of buoyancy (CoB)/center of mass and density affect the stability and speed of the robot, whereas the sculling movements contribute to propelling the robot even when its legs are detached from the ground. The relevance of these effects is demonstrated through robotic experiments and model simulations; moreover, by slightly changing the position of the CoB in the presence of the same feed-forward activation, a number of different behaviors (i.e. forward and backward locomotion at different speeds) are achieved.

Design and modelling of a 3D compliant leg for Bioloid

NASA Astrophysics Data System (ADS)

Couto, Mafalda; Santos, Cristina; Machado, José

2012-09-01

In the growing field of rehabilitation robotics, the modelling of a real robot is a complex and passionate challenge. On the crossing point of mechanics, physics and computer-science, the development of a complete 3D model involves the knowledge of the different physic properties, for an accurate simulation. In this paper, it is proposed the design of an efficient three-dimensional model of the quadruped Bioloid robot setting segmented pantographic legs, in order to actively retract the quadruped legs during locomotion and minimizing large forces due to shocks, such that the robot is able to safely and dynamically interact with the user or the environment.

Brain Activity Related to the Judgment of Face-Likeness: Correlation between EEG and Face-Like Evaluation.

PubMed

Nihei, Yuji; Minami, Tetsuto; Nakauchi, Shigeki

2018-01-01

Faces represent important information for social communication, because social information, such as face-color, expression, and gender, is obtained from faces. Therefore, individuals' tend to find faces unconsciously, even in objects. Why is face-likeness perceived in non-face objects? Previous event-related potential (ERP) studies showed that the P1 component (early visual processing), the N170 component (face detection), and the N250 component (personal detection) reflect the neural processing of faces. Inverted faces were reported to enhance the amplitude and delay the latency of P1 and N170. To investigate face-likeness processing in the brain, we explored the face-related components of the ERP through a face-like evaluation task using natural faces, cars, insects, and Arcimboldo paintings presented upright or inverted. We found a significant correlation between the inversion effect index and face-like scores in P1 in both hemispheres and in N170 in the right hemisphere. These results suggest that judgment of face-likeness occurs in a relatively early stage of face processing.

Brain Activity Related to the Judgment of Face-Likeness: Correlation between EEG and Face-Like Evaluation

PubMed Central

Nihei, Yuji; Minami, Tetsuto; Nakauchi, Shigeki

2018-01-01

Faces represent important information for social communication, because social information, such as face-color, expression, and gender, is obtained from faces. Therefore, individuals' tend to find faces unconsciously, even in objects. Why is face-likeness perceived in non-face objects? Previous event-related potential (ERP) studies showed that the P1 component (early visual processing), the N170 component (face detection), and the N250 component (personal detection) reflect the neural processing of faces. Inverted faces were reported to enhance the amplitude and delay the latency of P1 and N170. To investigate face-likeness processing in the brain, we explored the face-related components of the ERP through a face-like evaluation task using natural faces, cars, insects, and Arcimboldo paintings presented upright or inverted. We found a significant correlation between the inversion effect index and face-like scores in P1 in both hemispheres and in N170 in the right hemisphere. These results suggest that judgment of face-likeness occurs in a relatively early stage of face processing. PMID:29503612

On the relationship between lower extremity muscles activation and peak vertical and posterior ground reaction forces during single leg drop landing.

PubMed

Mahaki, M; Mi'mar, R; Mahaki, B

2015-10-01

Anterior cruciate ligament (ACL) injury continues to be an important medical issue for athletes participating in sports. Vertical and posterior ground reaction forces have received considerable attention for their potential influence on ACL injuries. The purpose of this study was to examine the relationship between electromyographic activity of lower extremity muscles and the peak vertical and posterior ground reaction forces during single leg drop landing. Thirteen physical education male students participated in this correlation study. Electromyographic activities of gluteus medius, biceps femoris, medial gastrocnemius, soleus as well as anterior tibialis muscles along with ground reaction forces were measured. Participants performed single-leg landing from a 0.3 m height on to a force platform. Landing was divided into two phases: 100 ms preceding ground contact and 100 ms proceeding ground contact. Pearson correlation test was used to determine the relationships between these muscles activity and peak vertical and posterior ground reaction forces. The results of the study indicated that the activity of soleus and tibialis anterior in pre-landing phase were positively correlated with peak vertical ground reaction force ([P≤0.04], [P≤0.008], respectively). However, no significant correlation was found between the activities of other muscles in pre-landing phase and peak vertical as well as peak posterior ground reaction forces. Also, no significant correlation was found between the activities of muscles in post-landing phase and peak vertical as well as peak posterior ground reaction forces. Soleus loading shifts the proximal tibia posterior at the knee joint and tibialis anterior prevent hyperporonation of the ankle, a mechanisms of ACL injury. Hence, neuromuscular training promoting preparatory muscle activity in these muscles may reduce the incidence of ACL injuries.

Leg pairs as virtual wheels

NASA Astrophysics Data System (ADS)

Howe, Russel; Duttweiler, Mark; Khanlian, Luke; Setrakian, Mark

2005-05-01

We propose the use of virtual wheels as the starting point of a new vehicle design. Each virtual wheel incorporates a pair of simple legs that, by simulating the rotary motion and ground contact of a traditional wheel, combine many of the benefits of legged and wheeled motion. We describe the use of virtual wheels in the design of a robotic mule, presenting an analysis of the mule's mobility the results of our efforts to model and build such a device.

Detail of array panels, Face B, with active and terminated ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Detail of array panels, Face B, with active and terminated dipole elements - Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, Techinical Equipment Building, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA

ORTHOPEDIC LEG BRACE

NASA Technical Reports Server (NTRS)

Myers, William Neil (Inventor)

2005-01-01

Knee braces generally have been rigid in both the knee bending direction and in the knee straightening direction unless a manually operated release is incorporated in them to allow the knee to bend. Desirably a braced knee joint should effectively duplicate the compound, complex, actions of a normal knee. The key to knee braces is the knee joint housing. The housing herein carries a number of cam action pawls. with teeth adapted to engage the internal teeth of a ratchet ring mounted in the housing. Cam action return springs and the shape of the cam action pawl teeth allow rotation of the ratchet ring in a leg straightening direction while still supporting a load. The leg can then be extended during walking while at the same time being prevented by the cam action pawls from buckling in the knee bending direction.

Amygdala atrophy affects emotion-related activity in face-responsive regions in frontotemporal degeneration.

PubMed

De Winter, François-Laurent; Van den Stock, Jan; de Gelder, Beatrice; Peeters, Ronald; Jastorff, Jan; Sunaert, Stefan; Vanduffel, Wim; Vandenberghe, Rik; Vandenbulcke, Mathieu

2016-09-01

In the healthy brain, modulatory influences from the amygdala commonly explain enhanced activation in face-responsive areas by emotional facial expressions relative to neutral expressions. In the behavioral variant frontotemporal dementia (bvFTD) facial emotion recognition is impaired and has been associated with atrophy of the amygdala. By combining structural and functional MRI in 19 patients with bvFTD and 20 controls we investigated the neural effects of emotion in face-responsive cortex and its relationship with amygdalar gray matter (GM) volume in neurodegeneration. Voxel-based morphometry revealed decreased GM volume in anterior medio-temporal regions including amygdala in patients compared to controls. During fMRI, we presented dynamic facial expressions (fear and chewing) and their spatiotemporally scrambled versions. We found enhanced activation for fearful compared to neutral faces in ventral temporal cortex and superior temporal sulcus in controls, but not in patients. In the bvFTD group left amygdalar GM volume correlated positively with emotion-related activity in left fusiform face area (FFA). This correlation was amygdala-specific and driven by GM in superficial and basolateral (BLA) subnuclei, consistent with reported amygdalar-cortical networks. The data suggests that anterior medio-temporal atrophy in bvFTD affects emotion processing in distant posterior areas. Copyright © 2016 Elsevier Ltd. All rights reserved.

Injury due to leg bands in willow flycatchers

USGS Publications Warehouse

Sedgwick, J.A.; Klus, R.J.

1997-01-01

We report an apparently unusually high incidence of leg injury in Willow Flycatchers (Empidonax traillii) as a result of banding and color banding. Color bands and U.S. Fish and Wildlife Service (USFWS) bands applied to Willow Flycatchers from 1988-1995 resulted in an overall leg injury rate of 9.6% to birds returning to our study areas in subsequent years. Most injuries occurred on legs with only color band(s) (58.3%) or on legs with both a USFWS band and a color band (35%); only 6.7% of injuries (4/60) were due to USFWS bands alone, yielding an overall USFWS band injury rate of only 0.6%. Injuries ranged from severe (swollen, bleeding legs; a missing foot) to relatively minor (irritations on the tarsus). Amputation of the foot occurred in 33.9% of the cases. Return rates of adult injured birds in the year(s) following injury were significantly lower than for the population at large.

The effect of leg preference on postural stability in healthy athletes.

PubMed

Huurnink, Arnold; Fransz, Duncan P; Kingma, Idsart; Hupperets, Maarten D W; van Dieën, Jaap H

2014-01-03

In research regarding postural stability, leg preference is often tested and controlled for. However, leg preference may vary between tasks. As athletes are a group of interest for postural stability testing, we evaluated the effect of five leg preference tasks categorization (step up, hop, ball kick, balance, pick up) on single-leg postural stability of 16 field hockey athletes. The 'center of pressure speed' was calculated as the primary outcome variable of single-leg postural stability. Secondary variables were 'mean length of the GRF vector in the horizontal plane', 'mean length of the ankle angular velocity vector', and 'mean length of the hip angular velocity vector', as well as the separate outcomes per degree of freedom. Results showed that leg preference was inconsistent between leg preference tasks. Moreover, the primary and secondary variables yielded no significant difference between the preferred and non-preferred legs, regardless of the applied leg preference task categorization (p>0.05). The present findings do not support the usability of leg preference tasks in controlling for bias of postural stability. In conclusion, none of the applied leg preference tasks revealed a significant effect on postural stability in healthy field hockey athletes. © 2013 Published by Elsevier Ltd.

Clinical Characteristics of Mixed Arteriovenous Leg Ulcers: A Descriptive Study.

PubMed

Marin, Joseph A; Woo, Kevin Y

The purpose of this study was to identify the clinical characteristics of mixed arteriovenous leg ulcers (MLU) that differentiated them from venous leg ulcers (VLU). Secondary analysis of data from larger electronic database. The sample comprised 1007 persons with lower extremity ulcers. Two hundred sixty three individuals with MLU were compared to 744 individuals with VLU; their ankle brachial indices were 0.51-0.90 and 0.91-.30 respectively. Subjects were drawn from community care settings from across Canada. Data concerning baseline demographic and pertinent clinical characteristics including ulcer history were collected using multiple validated instruments. The Leg Ulcer Assessment Tool was used to collect demographic and pertinent medical history, The Short Form Health Survey 12 and the Euro Wuol 5D (EQ-5D) were used to measure health related quality of life, the numeric pain scales was used to measure character and intensity of pain. Groups were compared using χ or Mann-Whitney U. Individuals with MLU were significantly older, has lower body mass index, a history of smoking, and more comorbid conditions than subjects with VLU. In many cases, clinical presentation was indicative of significant arterial insufficiency including cool extremities, shiny, cracked and inelastic skin, impaired capillary refill, and weak pedal pulses. Ulcer pain was highly prevalent, but overall pain rating was similar between groups. Mixed arteriovenous leg ulcers were associated with lower health related quality of life, greater mobility impairments, and more deficits in self-care and usual activities. Greater knowledge and understanding of the distinct characteristics of MLU is critical for appropriate screening, prevention, assessment and management of persons with this form of leg ulcer. Pain and health related quality of life factors are important considerations when evaluating and managing these patients.

The effect of swinging the arms on muscle activation and production of leg force during ski skating at different skiing speeds.

PubMed

Göpfert, Caroline; Lindinger, Stefan J; Ohtonen, Olli; Rapp, Walter; Müller, Erich; Linnamo, Vesa

2016-06-01

The study investigated the effects of arm swing during leg push-off in V2-alternate/G4 skating on neuromuscular activation and force production by the leg muscles. Nine skilled cross-country skiers performed V2-alternate skating without poles at moderate, high, and maximal speeds, both with free (SWING) and restricted arm swing (NOSWING). Maximal speed was 5% greater in SWING (P<0.01), while neuromuscular activation and produced forces did not differ between techniques. At both moderate and high speed the maximal (2% and 5%, respectively) and average (both 5%) vertical force and associated impulse (10% and 14%) were greater with SWING (all P<0.05). At high speed range of motion and angular velocity of knee flexion were 24% greater with SWING (both P<0.05), while average EMG of m. biceps femoris was 31% lower (all P<0.05) in SWING. In a similar manner, the average EMG of m. vastus medialis and m. biceps femoris were lower (17% and 32%, P<0.05) during the following knee extension. Thus, swinging the arms while performing V2-alternate can enhance both maximal speed and skiing economy at moderate and, in particularly, high speeds. Copyright © 2016 Elsevier B.V. All rights reserved.

In the face of fear: Anxiety sensitizes defensive responses to fearful faces

PubMed Central

Grillon, Christian; Charney, Danielle R.

2011-01-01

Fearful faces readily activate the amygdala. Yet, whether fearful faces evoke fear is unclear. Startle studies show no potentiation of startle by fearful faces, suggesting that such stimuli do not activate defense mechanisms. However, the response to biologically relevant stimuli may be sensitized by anxiety. The present study tested the hypothesis that startle would not be potentiated by fearful faces in a safe context, but that startle would be larger during fearful faces compared to neutral faces in a threat-of-shock context. Subjects viewed fearful and neutral faces in alternating periods of safety and threat of shock. Acoustic startle stimuli were presented in the presence and absence of the faces. Startle was transiently potentiated by fearful faces compared to neutral faces in the threat periods. This suggests that although fearful faces do not prompt behavioral mobilization in an innocuous context, they can do so in an anxiogenic one. PMID:21824155

The effect of face patch microstimulation on perception of faces and objects.

PubMed

Moeller, Sebastian; Crapse, Trinity; Chang, Le; Tsao, Doris Y

2017-05-01

What is the range of stimuli encoded by face-selective regions of the brain? We asked how electrical microstimulation of face patches in macaque inferotemporal cortex affects perception of faces and objects. We found that microstimulation strongly distorted face percepts and that this effect depended on precise targeting to the center of face patches. While microstimulation had no effect on the percept of many non-face objects, it did affect the percept of some, including non-face objects whose shape is consistent with a face (for example, apples) as well as somewhat facelike abstract images (for example, cartoon houses). Microstimulation even perturbed the percept of certain objects that did not activate the stimulated face patch at all. Overall, these results indicate that representation of facial identity is localized to face patches, but activity in these patches can also affect perception of face-compatible non-face objects, including objects normally represented in other parts of inferotemporal cortex.

Anterior cruciate ligament injury alters preinjury lower extremity biomechanics in the injured and uninjured leg: the JUMP-ACL study.

PubMed

Goerger, Benjamin M; Marshall, Stephen W; Beutler, Anthony I; Blackburn, J Troy; Wilckens, John H; Padua, Darin A

2015-02-01

Information as to how anterior cruciate ligament (ACL) injury and reconstructive surgery (ACLR) alter lower extremity biomechanics may improve rehabilitation and return to play guidelines, reducing the risk for repeat ACL injury. To compare lower extremity biomechanics before ACL injury and after subsequent ACLR for the injured and uninjured leg. Baseline unilateral lower extremity biomechanics were collected on the dominant leg of participants without ACL injury when they entered the Joint Undertaking to Monitor and Prevent ACL (JUMP-ACL) study. Thirty-one participants with subsequent ACL injury, reconstructive surgery and full return to physical activity completed repeat, follow-up biomechanical testing, as did 39 uninjured, matched controls. Not all injured participants suffered injury to the dominant leg, requiring separation of those with ACL injury into two groups: ACLR-injured leg group (n=12) and ACLR-uninjured leg group (n=19). We compared the landing biomechanics of these three groups (ACLR-injured leg, ACLR-uninjured leg, control) before ACL injury (baseline) with biomechanics after ACL injury, surgery and return to physical activity (follow-up). ACL injury and ACLR altered lower extremity biomechanics, as both ACLR groups demonstrated increases in frontal plane movement (increased hip adduction and knee valgus). The ACLR-injured leg group also exhibited decreased sagittal plane loading (decreased anterior tibial shear force, knee extension moment and hip flexion moment). No high-risk biomechanical changes were observed in control group participants. ACL injury and ACLR caused movement pattern alterations of the injured and uninjured leg that have previously shown to increase the risk for future non-contact ACL injury. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Integrated system for single leg walking

NASA Astrophysics Data System (ADS)

Simmons, Reid; Krotkov, Eric; Roston, Gerry

1990-07-01

The Carnegie Mellon University Planetary Rover project is developing a six-legged walking robot capable of autonomously navigating, exploring, and acquiring samples in rugged, unknown environments. This report describes an integrated software system capable of navigating a single leg of the robot over rugged terrain. The leg, based on an early design of the Ambler Planetary Rover, is suspended below a carriage that slides along rails. To walk, the system creates an elevation map of the terrain from laser scanner images, plans an appropriate foothold based on terrain and geometric constraints, weaves the leg through the terrain to position it above the foothold, contacts the terrain with the foot, and applies force enough to advance the carriage along the rails. Walking both forward and backward, the system has traversed hundreds of meters of rugged terrain including obstacles too tall to step over, trenches too deep to step in, closely spaced obstacles, and sand hills. The implemented system consists of a number of task-specific processes (two for planning, two for perception, one for real-time control) and a central control process that directs the flow of communication between processes.

Agreement and correlation between the straight leg raise and slump tests in subjects with leg pain.

PubMed

Walsh, Jeremy; Hall, Toby

2009-01-01

The straight leg raise (SLR) and slump tests have traditionally been used to identify nerve root compression arising from disk herniation. However, they may be more appropriate as tests of lumbosacral neural tissue mechanosensitivity. The aim of this study was to determine agreement and correlation between the SLR and slump tests in a population presenting with back and leg pain. This was an observational, cross-sectional study design. Forty-five subjects with unilateral leg pain were recruited from an outpatient Back Pain Screening Clinic at a large teaching hospital in Ireland. The SLR and slump tests were performed on each side. In the event of symptom reproduction, the ankle was dorsiflexed. Reproduction of presenting symptoms, which were intensified by ankle dorsiflexion, was interpreted as a positive test. An inclinometer was used to measure range of motion (ROM). There was substantial agreement between SLR and slump test interpretation (kappa = 0.69) with good correlation in ROM between the 2 tests (r = 0.64) on the symptomatic side. In subjects who had positive results, ROM for both tests was significantly reduced compared to ROM on the contralateral side and ROM in subjects who had negative results. When the SLR and slump tests are interpreted as positive in the event of reproduction of presenting leg pain that are intensified by ankle dorsiflexion, these tests show substantial agreement and good correlation in the leg pain population. When interpreted in this way, these tests may be appropriate tests of neural tissue mechanosensitivity, but further criteria must be met before a definitive conclusion in relation to neural tissue mechanosensitivity may be drawn.

Greater sensitivity of the cortical face processing system to perceptually-equated face detection

PubMed Central

Maher, S.; Ekstrom, T.; Tong, Y.; Nickerson, L.D.; Frederick, B.; Chen, Y.

2015-01-01

Face detection, the perceptual capacity to identify a visual stimulus as a face before probing deeper into specific attributes (such as its identity or emotion), is essential for social functioning. Despite the importance of this functional capacity, face detection and its underlying brain mechanisms are not well understood. This study evaluated the roles that the cortical face processing system, which is identified largely through studying other aspects of face perception, play in face detection. Specifically, we used functional magnetic resonance imaging (fMRI) to examine the activations of the fusifom face area (FFA), occipital face area (OFA) and superior temporal sulcus (STS) when face detection was isolated from other aspects of face perception and when face detection was perceptually-equated across individual human participants (n=20). During face detection, FFA and OFA were significantly activated, even for stimuli presented at perceptual-threshold levels, whereas STS was not. During tree detection, however, FFA and OFA were responsive only for highly salient (i.e., high contrast) stimuli. Moreover, activation of FFA during face detection predicted a significant portion of the perceptual performance levels that were determined psychophysically for each participant. This pattern of result indicates that FFA and OFA have a greater sensitivity to face detection signals and selectively support the initial process of face vs. non-face object perception. PMID:26592952

Compliant leg behaviour explains basic dynamics of walking and running

PubMed Central

Geyer, Hartmut; Seyfarth, Andre; Blickhan, Reinhard

2006-01-01

The basic mechanics of human locomotion are associated with vaulting over stiff legs in walking and rebounding on compliant legs in running. However, while rebounding legs well explain the stance dynamics of running, stiff legs cannot reproduce that of walking. With a simple bipedal spring–mass model, we show that not stiff but compliant legs are essential to obtain the basic walking mechanics; incorporating the double support as an essential part of the walking motion, the model reproduces the characteristic stance dynamics that result in the observed small vertical oscillation of the body and the observed out-of-phase changes in forward kinetic and gravitational potential energies. Exploring the parameter space of this model, we further show that it not only combines the basic dynamics of walking and running in one mechanical system, but also reveals these gaits to be just two out of the many solutions to legged locomotion offered by compliant leg behaviour and accessed by energy or speed. PMID:17015312

Actometry in measuring the symptom severity of restless legs syndrome.

PubMed

Tuisku, K; Holi, M M; Wahlbeck, K; Ahlgren, A J; Lauerma, H

2005-05-01

In a previous, controlled study we demonstrated that the general lower limb activity measured by three-channel actometry is a promising objective measure of restless legs syndrome (RLS) severity. In the present study we have further evaluated the method in measuring RLS symptom severity in an open, single-day pramipexole intervention with 15 RLS patients. Both our standardized actometric parameters (nocturnal lower limb activity and controlled rest activity) decreased significantly during the intervention in parallel with the subjectively reported relief of RLS symptoms.

The effect of age and unilateral leg immobilization for 2 weeks on substrate utilization during moderate‐intensity exercise in human skeletal muscle

PubMed Central

Gram, M.; Dybboe, R.; Kuhlman, A. B.; Prats, C.; Greenhaff, P. L.; Constantin‐Teodosiu, D.; Birk, J. B.; Wojtaszewski, J. F. P.; Dela, F.; Helge, J. W.

2016-01-01

Key points This study aimed to provide molecular insight into the differential effects of age and physical inactivity on the regulation of substrate metabolism during moderate‐intensity exercise.Using the arteriovenous balance technique, we studied the effect of immobilization of one leg for 2 weeks on leg substrate utilization in young and older men during two‐legged dynamic knee‐extensor moderate‐intensity exercise, as well as changes in key proteins in muscle metabolism before and after exercise.Age and immobilization did not affect relative carbohydrate and fat utilization during exercise, but the older men had higher uptake of exogenous fatty acids, whereas the young men relied more on endogenous fatty acids during exercise.Using a combined whole‐leg and molecular approach, we provide evidence that both age and physical inactivity result in intramuscular lipid accumulation, but this occurs only in part through the same mechanisms. Abstract Age and inactivity have been associated with intramuscular triglyceride (IMTG) accumulation. Here, we attempt to disentangle these factors by studying the effect of 2 weeks of unilateral leg immobilization on substrate utilization across the legs during moderate‐intensity exercise in young (n = 17; 23 ± 1 years old) and older men (n = 15; 68 ± 1 years old), while the contralateral leg served as the control. After immobilization, the participants performed two‐legged isolated knee‐extensor exercise at 20 ± 1 W (∼50% maximal work capacity) for 45 min with catheters inserted in the brachial artery and both femoral veins. Biopsy samples obtained from vastus lateralis muscles of both legs before and after exercise were used for analysis of substrates, protein content and enzyme activities. During exercise, leg substrate utilization (respiratory quotient) did not differ between groups or legs. Leg fatty acid uptake was greater in older than in young men, and although young men demonstrated net

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

PubMed

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

2016-12-01

Clinicians use the single-leg hop test to assess readiness for return to sports after knee injury. Few studies have reported the results of single-leg hop testing after meniscectomy. Additionally, the contributions of impairments in quadriceps strength and psychosocial factors to single-leg hop performance are unknown. To compare single-leg hop performance (distance and landing mechanics) between limbs and to examine the association of single-leg hop performance with quadriceps strength and psychosocial factors in patients with meniscectomy. Descriptive laboratory study. A total of 22 subjects who underwent meniscectomy for traumatic meniscal tears received either standard rehabilitation alone or with additional quadriceps strengthening. Testing was conducted immediately postrehabilitation and at 1 year postsurgery. A single-leg hop test was performed bilaterally, and hop distance was used to create a hop symmetry index. Landing mechanics (peak knee flexion angle, knee extension moment, and peak vertical ground-reaction force) were analyzed with a motion-capture system and a force plate. An isokinetic dynamometer (60 deg/s) assessed knee extensor peak torque and rate of torque development (RTD 0-200ms and RTD 0-peak torque ). Questionnaires assessed fear of reinjury (Tampa Scale for Kinesiophobia [TSK-11]) and self-efficacy (Knee Activity Self-Efficacy [KASE]). Rehabilitation groups did not significantly differ in single-leg hop performance; therefore, groups were combined for further analyses. The mean hop symmetry index was 88.6% and 98.9% at postrehabilitation and 1 year postsurgery, respectively. Compared with the nonsurgical limb, the surgical limb showed decreased peak knee flexion angle at postrehabilitation and decreased knee extension moment at 1 year postsurgery. The hop symmetry index was positively associated with peak torque, RTD 0-200ms , and the KASE score at postrehabilitation. Moreover, at postrehabilitation, the peak knee flexion angle was

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

Background: Clinicians use the single-leg hop test to assess readiness for return to sports after knee injury. Few studies have reported the results of single-leg hop testing after meniscectomy. Additionally, the contributions of impairments in quadriceps strength and psychosocial factors to single-leg hop performance are unknown. Purpose: To compare single-leg hop performance (distance and landing mechanics) between limbs and to examine the association of single-leg hop performance with quadriceps strength and psychosocial factors in patients with meniscectomy. Study Design: Descriptive laboratory study. Methods: A total of 22 subjects who underwent meniscectomy for traumatic meniscal tears received either standard rehabilitation alone or with additional quadriceps strengthening. Testing was conducted immediately postrehabilitation and at 1 year postsurgery. A single-leg hop test was performed bilaterally, and hop distance was used to create a hop symmetry index. Landing mechanics (peak knee flexion angle, knee extension moment, and peak vertical ground-reaction force) were analyzed with a motion-capture system and a force plate. An isokinetic dynamometer (60 deg/s) assessed knee extensor peak torque and rate of torque development (RTD0-200ms and RTD0–peak torque). Questionnaires assessed fear of reinjury (Tampa Scale for Kinesiophobia [TSK-11]) and self-efficacy (Knee Activity Self-Efficacy [KASE]). Results: Rehabilitation groups did not significantly differ in single-leg hop performance; therefore, groups were combined for further analyses. The mean hop symmetry index was 88.6% and 98.9% at postrehabilitation and 1 year postsurgery, respectively. Compared with the nonsurgical limb, the surgical limb showed decreased peak knee flexion angle at postrehabilitation and decreased knee extension moment at 1 year postsurgery. The hop symmetry index was positively associated with peak torque, RTD0-200ms, and the KASE score at postrehabilitation. Moreover, at

Swimming with stiff legs at low Reynolds number.

PubMed

Takagi, Daisuke

2015-08-01

Locomotion at low Reynolds number is not possible with cycles of reciprocal motion, an example being the oscillation of a single pair of rigid paddles or legs. Here, I demonstrate the possibility of swimming with two or more pairs of legs. They are assumed to oscillate collectively in a metachronal wave pattern in a minimal model based on slender-body theory for Stokes flow. The model predicts locomotion in the direction of the traveling wave, as commonly observed along the body of free-swimming crustaceans. The displacement of the body and the swimming efficiency depend on the number of legs, the amplitude, and the phase of oscillations. This study shows that paddling legs with distinct orientations and phases offers a simple mechanism for driving flow.

Dimensional synthesis of a leg mechanism

NASA Astrophysics Data System (ADS)

Pop, F.; Lovasz, E.-Ch; Pop, C.; Dolga, V.

2016-08-01

An eight bar leg mechanism dimensional synthesis is presented. The mathematical model regarding the synthesis is described and the results obtained after computation are verified with help of 2D mechanism simulation in Matlab. This mechanism, inspired from proposed solution of Theo Jansen, is integrated into the structure of a 2 DOF quadruped robot. With help of the kinematic synthesis method described, it is tried to determine new dimensions for the mechanism, based on a set of initial conditions. These are established by taking into account the movement of the end point of the leg mechanism, which enters in contact with the ground, during walking. An optimization process based on the results obtained can be conducted further in order to find a better solution for the leg mechanism.

Continuous leg dyskinesia assessment in Parkinson's disease -clinical validity and ecological effect.

PubMed

Ramsperger, Robert; Meckler, Stefan; Heger, Tanja; van Uem, Janet; Hucker, Svenja; Braatz, Ulrike; Graessner, Holm; Berg, Daniela; Manoli, Yiannos; Serrano, J Artur; Ferreira, Joaquim J; Hobert, Markus A; Maetzler, Walter

2016-05-01

Dyskinesias in Parkinson's disease (PD) patients are a common side effect of long-term dopaminergic therapy and are associated with motor dysfunctions, including gait and balance deficits. Although promising compounds have been developed to treat these symptoms, clinical trials have failed. This failure may, at least partly, be explained by the lack of objective and continuous assessment strategies. This study tested the clinical validity and ecological effect of an algorithm that detects and quantifies dyskinesias of the legs using a single ankle-worn sensor. Twenty-three PD patients (seven with leg dyskinesias) and 13 control subjects were investigated in the lab. Participants performed purposeful daily activity-like tasks while being video-taped. Clinical evaluation was performed using the leg dyskinesia item of the Unified Dyskinesia Rating Scale. The ecological effect of the developed algorithm was investigated in a multi-center, 12-week, home-based sub-study that included three patients with and seven without dyskinesias. In the lab-based sub-study, the sensor-based algorithm exhibited a specificity of 98%, a sensitivity of 85%, and an accuracy of 0.96 for the detection of dyskinesias and a correlation level of 0.61 (p < 0.001) with the clinical severity score. In the home-based sub-study, all patients could be correctly classified regarding the presence or absence of leg dyskinesias, supporting the ecological relevance of the algorithm. This study provides evidence of clinical validity and ecological effect of an algorithm derived from a single sensor on the ankle for detecting leg dyskinesias in PD patients. These results should motivate the investigation of leg dyskinesias in larger studies using wearable sensors. Copyright © 2016 Elsevier Ltd. All rights reserved.

Coordination of planar cell polarity pathways through Spiny-legs

PubMed Central

Ambegaonkar, Abhijit A; Irvine, Kenneth D

2015-01-01

Morphogenesis and physiology of tissues and organs requires planar cell polarity (PCP) systems that orient and coordinate cells and their behaviors, but the relationship between PCP systems has been controversial. We have characterized how the Frizzled and Dachsous-Fat PCP systems are connected through the Spiny-legs isoform of the Prickle-Spiny-legs locus. Two different components of the Dachsous-Fat system, Dachsous and Dachs, can each independently interact with Spiny-legs and direct its localization in vivo. Through characterization of the contributions of Prickle, Spiny-legs, Dachsous, Fat, and Dachs to PCP in the Drosophila wing, eye, and abdomen, we define where Dachs-Spiny-legs and Dachsous-Spiny-legs interactions contribute to PCP, and provide a new understanding of the orientation of polarity and the basis of PCP phenotypes. Our results support the direct linkage of PCP systems through Sple in specific locales, while emphasizing that cells can be subject to and must ultimately resolve distinct, competing PCP signals. DOI: http://dx.doi.org/10.7554/eLife.09946.001 PMID:26505959

Is EMG of the lower leg dependent on weekly running mileage?

PubMed

Baur, H; Hirschmüller, A; Müller, S; Cassel, M; Mayer, F

2012-01-01

Neuromuscular activity of the lower leg is dependent on the task performed, speed of movement and gender. Whether training volume influences neuromuscular activity is not known. The EMG of physically active persons differing in running mileage was analysed to investigate this. 55 volunteers were allocated to a low (LM: < 30 km), intermediate (IM: > 30 km & < 45 km) or high mileage (HM: > 45 km) group according to their weekly running volume. Neuromuscular activity of the lower leg was measured during running (3.33 m·s - 1). Mean amplitude values for preactivation, weight acceptance and push-off were calculated and normalised to the mean activity of the entire gait cycle.Higher activity in the gastrocnemius group was observed in weight acceptance in LM compared to IM (+30%) and HM (+25%) but lower activity was present in the push-off for LM compared to IM and HM. For the peroneal muscle, differences were present in the push-off where HM showed increased activity compared to IM (+24%) and LM (+60%). The tibial muscle revealed slightly lower activity during preactivation for the high mileage runners. Neuromuscular activity differs during stance between the high and intermediate group compared to low mileage runners. Slight adaptations in neuromuscular activation indicate a more target-oriented activation strategy possibly due to repetitive training in runners with higher weekly mileage. © Georg Thieme Verlag KG Stuttgart · New York.

The Lower Extremity Biomechanics of Single- and Double-Leg Stop-Jump Tasks

PubMed Central

2011-01-01

The anterior cruciate ligament (ACL) injury is a common occurrence in sports requiring stop-jump tasks. Single- and double-leg stop-jump techniques are frequently executed in sports. The higher risk of ACL injury in single-leg drop landing task compared to a double-leg drop landing task has been identified. However the injury bias between single- and double-leg landing techniques has not been investigated for stop-jump tasks. The purpose of this study was to determine the differences between single- and double-leg stop-jump tasks in knee kinetics that were influenced by the lower extremity kinematics during the landing phase. Ground reaction force, lower extremity kinematics, and knee kinetics data during the landing phase were obtained from 10 subjects performing single- and double-leg stop-jump tasks, using motion-capture system and force palates. Greater peak posterior and vertical ground reaction forces, and peak proximal tibia anterior and lateral shear forces (p < 0.05) during landing phase were observed of single-leg stop-jump. Single-leg stop-jump exhibited smaller hip and knee flexion angle, and knee flexion angular velocity at initial foot contact with the ground (p < 0.05). We found smaller peak hip and knee flexion angles (p < 0.05) during the landing phase of single-leg stop-jump. These results indicate that single-leg landing may have higher ACL injury risk than double-leg landing in stop-jump tasks that may be influenced by the lower extremity kinematics during the landing phase. Key points Non-contact ACL injuries are more likely to occur during the single-leg stop-jump task than during the double-leg stop-jump task. Single-leg stop-jump exhibited greater peak proximal tibia anterior and lateral shear forces, and peak posterior and vertical ground reaction forces during the landing phase than the double-leg stop-jump task. Single-leg stop-jump exhibited smaller hip flexion angle, knee flexion angle, and knee flexion angular velocity at initial foot

Imbibition dynamics on surfaces of legs of a small animal and on artificial surfaces mimicking them

NASA Astrophysics Data System (ADS)

Tani, Marie; Ishii, Daisuke; Ito, Shuto; Hariyama, Takahiko; Shimomura, Masatsugu; Okumura, Ko

2014-03-01

Recently, imbibition of textured surfaces covered with homogeneous micro-pillar arrays has been actively studied partly because of the potential for transport of a small amount of liquids. In most cases, the dynamics is described by the Washburn law, in which the imbibition distance scales with the square root of elapsed time, while a different scaling law has been recently found. In this study, we studied imbibition on legs of a small animal that absorbs water via its legs to find yet another scaling law. Furthermore, imbibition of artificial surfaces mimicking the leg surface was found to be described well by a composite theory.

Leg exoskeleton reduces the metabolic cost of human hopping.

PubMed

Grabowski, Alena M; Herr, Hugh M

2009-09-01

During bouncing gaits such as hopping and running, leg muscles generate force to enable elastic energy storage and return primarily from tendons and, thus, demand metabolic energy. In an effort to reduce metabolic demand, we designed two elastic leg exoskeletons that act in parallel with the wearer's legs; one exoskeleton consisted of a multiple leaf (MLE) and the other of a single leaf (SLE) set of fiberglass springs. We hypothesized that hoppers, hopping on both legs, would adjust their leg stiffness while wearing an exoskeleton so that the combination of the hopper and exoskeleton would behave as a linear spring-mass system with the same total stiffness as during normal hopping. We also hypothesized that decreased leg force generation while wearing an exoskeleton would reduce the metabolic power required for hopping. Nine subjects hopped in place at 2.0, 2.2, 2.4, and 2.6 Hz with and without an exoskeleton while we measured ground reaction forces, exoskeletal compression, and metabolic rates. While wearing an exoskeleton, hoppers adjusted their leg stiffness to maintain linear spring-mass mechanics and a total stiffness similar to normal hopping. Without accounting for the added weight of each exoskeleton, wearing the MLE reduced net metabolic power by an average of 6% and wearing the SLE reduced net metabolic power by an average of 24% compared with hopping normally at frequencies between 2.0 and 2.6 Hz. Thus, when hoppers used external parallel springs, they likely decreased the mechanical work performed by the legs and substantially reduced metabolic demand compared with hopping without wearing an exoskeleton.

Getting Your Sea Legs

PubMed Central

Stoffregen, Thomas A.; Chen, Fu-Chen; Varlet, Manuel; Alcantara, Cristina; Bardy, Benoît G.

2013-01-01

Sea travel mandates changes in the control of the body. The process by which we adapt bodily control to life at sea is known as getting one's sea legs. We conducted the first experimental study of bodily control as maritime novices adapted to motion of a ship at sea. We evaluated postural activity (stance width, stance angle, and the kinematics of body sway) before and during a sea voyage. In addition, we evaluated the role of the visible horizon in the control of body sway. Finally, we related data on postural activity to two subjective experiences that are associated with sea travel; seasickness, and mal de debarquement. Our results revealed rapid changes in postural activity among novices at sea. Before the beginning of the voyage, the temporal dynamics of body sway differed among participants as a function of their (subsequent) severity of seasickness. Body sway measured at sea differed among participants as a function of their (subsequent) experience of mal de debarquement. We discuss implications of these results for general theories of the perception and control of bodily orientation, for the etiology of motion sickness, and for general phenomena of perceptual-motor adaptation and learning. PMID:23840560

Getting Your Sea Legs.

PubMed

Stoffregen, Thomas A; Chen, Fu-Chen; Varlet, Manuel; Alcantara, Cristina; Bardy, Benoît G

2013-01-01

Sea travel mandates changes in the control of the body. The process by which we adapt bodily control to life at sea is known as getting one's sea legs. We conducted the first experimental study of bodily control as maritime novices adapted to motion of a ship at sea. We evaluated postural activity (stance width, stance angle, and the kinematics of body sway) before and during a sea voyage. In addition, we evaluated the role of the visible horizon in the control of body sway. Finally, we related data on postural activity to two subjective experiences that are associated with sea travel; seasickness, and mal de debarquement. Our results revealed rapid changes in postural activity among novices at sea. Before the beginning of the voyage, the temporal dynamics of body sway differed among participants as a function of their (subsequent) severity of seasickness. Body sway measured at sea differed among participants as a function of their (subsequent) experience of mal de debarquement. We discuss implications of these results for general theories of the perception and control of bodily orientation, for the etiology of motion sickness, and for general phenomena of perceptual-motor adaptation and learning.

Study on Mucin in Normal-Appearing Leg Skin.

PubMed

Fernandez-Flores, Angel

2017-03-01

Dermal deposits of mucin in the legs have been described associated with venous insufficiency. However, some degree of stasis dermatitis is generally common in aged individuals. Therefore, some amount of mucin is expected a priori in the reticular dermis of aged patients, even in the absence of clinical lesions. To test this hypothesis, the authors investigated the mucin in the legs of aged individuals without any dermatologic disease. Cutaneous samples were taken from the legs of 15 autopsy cases. A sample of the skin of the legs (either from the left or the right leg without any distinction being made) was randomly taken (without selecting any specific area or attending to macroscopical features). The skin samples were fixed in formaldehyde, and sections obtained from all samples were stained with hematoxylin and eosin, iron, and Alcian blue. Iron deposits were graded as 0/4 in 7 cases, as 1/4 in 4 cases, as 2/4 in 2 cases, and as 4/4 in 2 cases. Cases with greater deposits of iron also had other signs of stasis, such as neovascularization. All the samples scored 0 for dermal mucin deposits in the reticular dermis. The authors conclude that mucin deposits in the legs are not inherent to aging. Therefore, any mucin deposit in the reticular dermis, as well as expansion of the periadnexal dermis by mucin deposits, should be considered abnormal.

Kinematic and EMG Responses to Pelvis and Leg Assistance Force during Treadmill Walking in Children with Cerebral Palsy

PubMed Central

Kim, Janis; Arora, Pooja; Zhang, Yunhui

2016-01-01

Treadmill training has been used for improving locomotor function in children with cerebral palsy (CP), but the functional gains are relatively small, suggesting a need to improve current paradigms. The understanding of the kinematic and EMG responses to forces applied to the body of subjects during treadmill walking is crucial for improving current paradigms. The objective of this study was to determine the kinematics and EMG responses to the pelvis and/or leg assistance force. Ten children with spastic CP were recruited to participate in this study. A controlled assistance force was applied to the pelvis and/or legs during stance and swing phase of gait through a custom designed robotic system during walking. Muscle activities and spatial-temporal gait parameters were measured at different loading conditions during walking. In addition, the spatial-temporal gait parameters during overground walking before and after treadmill training were also collected. Applying pelvis assistance improved step height and applying leg assistance improved step length during walking, but applying leg assistance also reduced muscle activation of ankle flexor during the swing phase of gait. In addition, step length and self-selected walking speed significantly improved after one session of treadmill training with combined pelvis and leg assistance. PMID:27651955

Mapping attractor fields in face space: the atypicality bias in face recognition.

PubMed

Tanaka, J; Giles, M; Kremen, S; Simon, V

1998-09-01

A familiar face can be recognized across many changes in the stimulus input. In this research, the many-to-one mapping of face stimuli to a single face memory is referred to as a face memory's 'attractor field'. According to the attractor field approach, a face memory will be activated by any stimuli falling within the boundaries of its attractor field. It was predicted that by virtue of its location in a multi-dimensional face space, the attractor field of an atypical face will be larger than the attractor field of a typical face. To test this prediction, subjects make likeness judgments to morphed faces that contained a 50/50 contribution from an atypical and a typical parent face. The main result of four experiments was that the morph face was judged to bear a stronger resemblance to the atypical face parent than the typical face parent. The computational basis of the atypicality bias was demonstrated in a neural network simulation where morph inputs of atypical and typical representations elicited stronger activation of atypical output units than of typical output units. Together, the behavioral and simulation evidence supports the view that the attractor fields of atypical faces span over a broader region of face space that the attractor fields of typical faces.

[Design and application of medical electric leg-raising machine].

PubMed

Liang, Jintang; Chen, Jinyuan; Zhao, Zixian; Lin, Jinfeng; Li, Juanhong; Zhong, Jingliang

2017-08-01

Passive leg raising is widely used in clinic, but it lacks of specialized mechanical raise equipment. It requires medical staff to raise leg by hand or requires a multi-functional bed to raise leg, which takes time and effort. Therefore we have developed a new medical electric leg-raising machine. The equipment has the following characteristics: simple structure, stable performance, easy operation, fast and effective, safe and comfortable. The height range of the lifter is 50-120 cm, the range of the angle of raising leg is 10degree angle-80degree angle, the maximum supporting weight is 40 kg. Because of raising the height of the lower limbs and making precise angle, this equipment can completely replace the traditional manner of lifting leg by hand with multi-functional bed to lift patients' leg and can reduce the physical exhaustion and time consumption of medical staff. It can change the settings at any time to meet the needs of the patient; can be applied to the testing of PLR and dynamically assessing the hemodynamics; can prevent deep vein thrombosis and some related complications of staying in bed; and the machine is easy to be cleaned and disinfected, which can effectively avoid hospital acquired infection and cross infection; and can also be applied to emergency rescue of various disasters and emergencies.

Trunk, pelvis, hip, and knee kinematics, hip strength, and gluteal muscle activation during a single-leg squat in males and females with and without patellofemoral pain syndrome.

PubMed

Nakagawa, Theresa H; Moriya, Erika T U; Maciel, Carlos D; Serrão, Fábio V

2012-06-01

Controlled laboratory study using a cross-sectional design. To determine whether there are any differences between the sexes in trunk, pelvis, hip, and knee kinematics, hip strength, and gluteal muscle activation during the performance of a single-leg squat in individuals with patellofemoral pain syndrome (PFPS) and control participants. Though there is a greater incidence of PFPS in females, PFPS is also quite common in males. Trunk kinematics may affect hip and knee function; however, there is a lack of studies of the influence of the trunk in individuals with PFPS. Eighty subjects were distributed into 4 groups: females with PFPS, female controls, males with PFPS, and male controls. Trunk, pelvis, hip, and knee kinematics and gluteal muscle activation were evaluated during a single-leg squat. Hip abduction and external rotation eccentric strength was measured on an isokinetic dynamometer. Group differences were assessed using a 2-way multivariate analysis of variance (sex by PFPS status). Compared to controls, subjects with PFPS had greater ipsilateral trunk lean (mean ± SD, 9.3° ± 5.3° versus 6.7° ± 3.0°; P = .012), contralateral pelvic drop (10.3° ± 4.7° versus 7.4° ± 3.8°; P = .003), hip adduction (14.8° ± 7.8° versus 10.8° ± 5.6°; P<.0001), and knee abduction (9.2° ± 5.0° versus 5.8° ± 3.4°; P<.0001) when performing a single-leg squat. Subjects with PFPS also had 18% less hip abduction and 17% less hip external rotation strength. Compared to female controls, females with PFPS had more hip internal rotation (P<.05) and less muscle activation of the gluteus medius (P = .017) during the single-leg squat. Despite many similarities in findings for males and females with PFPS, there may be specific sex differences that warrant consideration in future studies and when clinically evaluating and treating females with PFPS.

An index for breathlessness and leg fatigue.

PubMed

Borg, E; Borg, G; Larsson, K; Letzter, M; Sundblad, B-M

2010-08-01

The features of perceived symptoms causing discontinuation of strenuous exercise have been scarcely studied. The aim was to characterize the two main symptoms causing the discontinuation of heavy work in healthy persons as well as describe the growth of symptoms during exercise. Breathlessness (b) and leg fatigue (l) were assessed using the Borg CR10 Scale and the Borg CR100 (centiMax) Scale, during a standardized exercise test in 38 healthy subjects (24-71 years). The b/l-relationships were calculated for terminal perceptions (ERI(b/l)), and the growth of symptoms determined by power functions for the whole test, as well as by growth response indexes (GRI). This latter index was constructed as a ratio between power levels corresponding to a very strong and a moderate perception. In the majority (71%) of the test subjects, leg fatigue was the dominant symptom at the conclusion of exercise (P<0.001) and the b/l ratio was 0.77 (CR10) and 0.75 (CR100), respectively. The GRI for breathlessness and leg fatigue was similar, with good correlations between GRI and the power function exponent (P<0.005). In healthy subjects, leg fatigue is the most common cause for discontinuing an incremental exercise test. The growth functions for breathlessness and leg fatigue during work are, however, almost parallel.

Impact of restless legs syndrome in patients with inflammatory bowel disease on sleep, fatigue, and quality of life.

PubMed

Schindlbeck, Katharina A; Becker, Janek; Berger, Felix; Mehl, Arne; Rewitzer, Charlotte; Geffe, Sarah; Koch, Peter M; Preiß, Jan C; Siegmund, Britta; Maul, Jochen; Marzinzik, Frank

2017-01-01

Inflammatory bowel disease has been associated with neurological symptoms including restless legs syndrome. Here, we investigated the impact of restless legs syndrome in patients with inflammatory bowel disease on sleep, fatigue, mood, cognition, and quality of life. Two groups of inflammatory bowel disease patients, with and without restless legs syndrome, were prospectively evaluated for sleep disorders, fatigue, daytime sleepiness, depression, anxiety, and health-related quality of life. Furthermore, global cognitive function, executive function, attention, and concentration were assessed in both groups. Disease activity and duration of inflammatory bowel disease as well as current medication were assessed by interview. Inflammatory bowel disease patients with and without restless legs syndrome were matched for age, education, severity, and duration of their inflammatory bowel disease. Patients with inflammatory bowel disease and clinically relevant restless leg syndrome suffered significantly more frequent from sleep disturbances including sleep latency and duration, more fatigue, and worse health-related quality of life as compared to inflammatory bowel disease patients without restless legs syndrome. Affect and cognitive function including cognitive flexibility, attention, and concentration showed no significant differences among groups, indicating to be not related to restless legs syndrome. Sleep disorders including longer sleep latency, shorter sleep duration, and fatigue are characteristic symptoms of restless legs syndrome in inflammatory bowel disease patients, resulting in worse health-related quality of life. Therefore, clinicians treating patients with inflammatory bowel disease should be alert for restless legs syndrome.

A face to remember: emotional expression modulates prefrontal activity during memory formation.

PubMed

Sergerie, Karine; Lepage, Martin; Armony, Jorge L

2005-01-15

Emotion can exert a modulatory role on episodic memory. Several studies have shown that negative stimuli (e.g., words, pictures) are better remembered than neutral ones. Although facial expressions are powerful emotional stimuli and have been shown to influence perception and attention processes, little is known about their effect on memory. We used functional magnetic resonance imaging (fMRI) in humans to investigate the effects of expression (happy, neutral, and fearful) on prefrontal cortex (PFC) activity during the encoding of faces, using a subsequent memory effect paradigm. Our results show that activity in right PFC predicted memory for faces, regardless of expression, while a homotopic region in the left hemisphere was associated with successful encoding only for faces with an emotional expression. These findings are consistent with the proposed role of right dorsolateral PFC in successful encoding of nonverbal material, but also suggest that left DLPFC may be a site where integration of memory and emotional processes occurs. This study sheds new light on the current controversy regarding the hemispheric lateralization of PFC in memory encoding.

Near-Infrared Spectroscopic Measurement of the Effect of Leg Dominance on Muscle Oxygen Saturation During Cycling

NASA Technical Reports Server (NTRS)

Ellerby, Gwenn E. C.; Lee, Stuart M. C.; Paunescu, Lelia Adelina; Pereira, Chelsea; Smith, Charles P.; Soller, Babs R.

2011-01-01

The effect of leg dominance on the symmetry of the biomechanics during cycling remains uncertain -- asymmetries have been observed in kinematics and kinetics, while symmetries were found in muscle activation. No studies have yet investigated the symmetry of muscle metabolism during cycling. Near-infrared spectroscopy (NIRS) provides a non-invasive method to investigate the metabolic responses of specific muscles during cycling. PURPOSE: To determine whether there was an effect of leg dominance on thigh muscle oxygen saturation (SmO2) during incrementally loaded submaximal cycling using NIRS. METHODS: Eight right leg dominant, untrained subjects (5 men, 3 women; 31+/-2 yrs; 168.6+/-1.0 cm; 67.2+/-1.8 kg, mean +/- SE) volunteered to participate. Spectra were collected bilaterally from the vastus lateralis (VL) during supine rest and cycling. SmO2 was calculated using previously published methods. Subjects pedaled at 65 rpm while resistance to pedaling was increased in 0.5 kp increments from 0.5 kp every 3 min until the subject reached 80% of age-predicted maximal heart rate. SmO2 was averaged over 3 min for each completed stage. A two-way ANOVA was performed to test for leg differences. A priori contrasts were used to compare work levels to rest. RESULTS: VL SmO2 was not different between the dominant and non-dominant legs at rest and during exercise (p=0.57). How SmO2 changed with workload was also not different between legs (p=0.32). SmO2 at 0.5 kp (60.3+/-4.0, p=0.12) and 1.0 kp (59.5+/-4.0, p=0.10) was not different from rest (69.1+/-4.0). SmO2 at 1.5 kp (55.4 4.0, p=0.02), 2.0 kp (55.7+/-5.0, p=0.04), and 2.5 kp (43.4+/-7.9, p=0.01) was significantly lower than rest. CONCLUSION: VL SmO2 during cycling is not different between dominant and non-dominant legs and decreases with moderate workload in untrained cyclists. Assuming blood flow is directed equally to both legs, similar levels of oxygen extraction (as indicated by SmO2) suggests the metabolic load of

Influence of respiratory muscle work on VO(2) and leg blood flow during submaximal exercise.

PubMed

Wetter, T J; Harms, C A; Nelson, W B; Pegelow, D F; Dempsey, J A

1999-08-01

The work of breathing (W(b)) normally incurred during maximal exercise not only requires substantial cardiac output and O(2) consumption (VO(2)) but also causes vasoconstriction in locomotor muscles and compromises leg blood flow (Q(leg)). We wondered whether the W(b) normally incurred during submaximal exercise would also reduce Q(leg). Therefore, we investigated the effects of changing the W(b) on Q(leg) via thermodilution in 10 healthy trained male cyclists [maximal VO(2) (VO(2 max)) = 59 +/- 9 ml. kg(-1). min(-1)] during repeated bouts of cycle exercise at work rates corresponding to 50 and 75% of VO(2 max). Inspiratory muscle work was 1) reduced 40 +/- 6% via a proportional-assist ventilator, 2) not manipulated (control), or 3) increased 61 +/- 8% by addition of inspiratory resistive loads. Increasing the W(b) during submaximal exercise caused VO(2) to increase; decreasing the W(b) was associated with lower VO(2) (DeltaVO(2) = 0.12 and 0.21 l/min at 50 and 75% of VO(2 max), respectively, for approximately 100% change in W(b)). There were no significant changes in leg vascular resistance (LVR), norepinephrine spillover, arterial pressure, or Q(leg) when W(b) was reduced or increased. Why are LVR, norepinephrine spillover, and Q(leg) influenced by the W(b) at maximal but not submaximal exercise? We postulate that at submaximal work rates and ventilation rates the normal W(b) required makes insufficient demands for VO(2) and cardiac output to require any cardiovascular adjustment and is too small to activate sympathetic vasoconstrictor efferent output. Furthermore, even a 50-70% increase in W(b) during submaximal exercise, as might be encountered in conditions where ventilation rates and/or inspiratory flow resistive forces are higher than normal, also does not elicit changes in LVR or Q(leg).

Leg deformation during imaginal ecdysis in the downy emerald, Cordulia aenea (Odonata, Corduliidae).

PubMed

Frantsevich, Leonid; Frantsevich, Ludmilla

2018-04-01

A dragonfly larva migrates from the water to the shore, perches on a plant stem and grasps it with strongly flexed legs. Adult legs inside the larval exoskeleton fit to the larval legs joint-to-joint. The adult emerges with stretched legs. During the molt, an imaginal leg must follow all the angles in exuvial joints. In turn, larval apodemes are withdrawn from imaginal legs. We visualized transient shapes of the imaginal legs by the instant fixation of insects at different moments of the molt, photographed isolated exuvial legs with the imaginal legs inside and then removed the exuvial sheath. Instant shapes of the imaginal tibia show sharp intrapodomere bends copying the angle in the larval femoro-tibial joint. The site of bending shifts distad during the molt. This is possible if the imaginal leg is pliable. The same problem of leg squeezing is also common in hemimetabolous insects as well as in other arthropods, whereas holometabolous insects overcome problems of a tight confinement either by using leg pliability in other ways but not squeezing (cyclorrhaphan flies, mosquitoes) or by pulling hardened legs out without change of their pupal zigzag configuration (moths, ants, honey bees). The pupal legs are not intended to grasp any external substrate. Copyright © 2018 Elsevier GmbH. All rights reserved.

Backward masked fearful faces enhance contralateral occipital cortical activity for visual targets within the spotlight of attention

PubMed Central

Reinke, Karen S.; LaMontagne, Pamela J.; Habib, Reza

2011-01-01

Spatial attention has been argued to be adaptive by enhancing the processing of visual stimuli within the ‘spotlight of attention’. We previously reported that crude threat cues (backward masked fearful faces) facilitate spatial attention through a network of brain regions consisting of the amygdala, anterior cingulate and contralateral visual cortex. However, results from previous functional magnetic resonance imaging (fMRI) dot-probe studies have been inconclusive regarding a fearful face-elicited contralateral modulation of visual targets. Here, we tested the hypothesis that the capture of spatial attention by crude threat cues would facilitate processing of subsequently presented visual stimuli within the masked fearful face-elicited ‘spotlight of attention’ in the contralateral visual cortex. Participants performed a backward masked fearful face dot-probe task while brain activity was measured with fMRI. Masked fearful face left visual field trials enhanced activity for spatially congruent targets in the right superior occipital gyrus, fusiform gyrus and lateral occipital complex, while masked fearful face right visual field trials enhanced activity in the left middle occipital gyrus. These data indicate that crude threat elicited spatial attention enhances the processing of subsequent visual stimuli in contralateral occipital cortex, which may occur by lowering neural activation thresholds in this retinotopic location. PMID:20702500

Atypical parietal lobe activity to subliminal faces in youth with a family history of alcoholism

PubMed Central

Peraza, Jennifer; Cservenka, Anita; Herting, Megan M.; Nagel, Bonnie J.

2015-01-01

Background Adults with alcohol use disorders (AUDs) show different behavioral and neurological functioning during emotional processing tasks from healthy controls. Adults with a family history (FHP) of AUD also show different activation in limbic brain areas, such as the amygdala. However, it is unclear if this pattern exists during adolescence before any episodes of heavy alcohol use. Objectives We hypothesized that the amygdalar response to subliminally-presented fearful faces would be reduced in FHP adolescents compared to peers who were family history negative (FHN) for AUD. Method An adapted Masked Faces paradigm was used to examine blood oxygen level-dependent response to subliminal fearful vs. neutral faces in 14 FHP (6 females, 8 males) and 15 FHN (6 females, 9 males) youth, ages 11–15 years. Both FHP and FHN youth had no history of heavy alcohol consumption. Results A significant difference was seen between groups in the left superior parietal lobule FHN youth showed deactivation to fearful and neutral masked faces compared to baseline, whereas FHP youth showed deactivation only to fearful masked faces. No significant differences in amygdalar activation were seen between groups. Conclusion The left superior parietal lobule is part of the fronto-parietal network, which has been implicated in attentional control. Lack of reduced neural activity to neutral faces among FHP youth may represent differences in suppressing attention networks to less salient emotional stimuli, or perhaps, a higher threshold of saliency for emotional stimuli among at-risk youth. PMID:25268683

Atypical parietal lobe activity to subliminal faces in youth with a family history of alcoholism.

PubMed

Peraza, Jennifer; Cservenka, Anita; Herting, Megan M; Nagel, Bonnie J

2015-03-01

Adults with alcohol use disorders (AUDs) show different behavioral and neurological functioning during emotional processing tasks from healthy controls. Adults with a family history (FHP) of AUD also show different activation in limbic brain areas, such as the amygdala. However, it is unclear if this pattern exists during adolescence before any episodes of heavy alcohol use. We hypothesized that the amygdalar response to subliminally-presented fearful faces would be reduced in FHP adolescents compared to peers who were family history negative (FHN) for AUD. An adapted Masked Faces paradigm was used to examine blood oxygen level-dependent response to subliminal fearful vs. neutral faces in 14 FHP (6 females, 8 males) and 15 FHN (6 females, 9 males) youth, ages 11-15 years. Both FHP and FHN youth had no history of heavy alcohol consumption. A significant difference was seen between groups in the left superior parietal lobule FHN youth showed deactivation to fearful and neutral masked faces compared to baseline, whereas FHP youth showed deactivation only to fearful masked faces. No significant differences in amygdalar activation were seen between groups. The left superior parietal lobule is part of the fronto-parietal network, which has been implicated in attentional control. Lack of reduced neural activity to neutral faces among FHP youth may represent differences in suppressing attention networks to less salient emotional stimuli, or perhaps, a higher threshold of saliency for emotional stimuli among at-risk youth.

Evaluation of Thermoelectric Performance and Durability of Functionalized Skutterudite Legs

NASA Astrophysics Data System (ADS)

Skomedal, Gunstein; Kristiansen, Nils R.; Sottong, Reinhard; Middleton, Hugh

2017-04-01

Thermoelectric generators are a promising technology for waste heat recovery. As new materials and devices enter a market penetration stage, it is of interest to employ fast and efficient measurement methods to evaluate the long-term stability of thermoelectric materials in combination with metallization and coating (functionalized thermoelectric legs). We have investigated a method for measuring several thermoelectric legs simultaneously. The legs are put under a common temperature gradient, and the electrical characteristics of each leg are measured individually during thermal cycling. Using this method, one can test different types of metallization and coating applied to skutterudite thermoelectric legs and look at the relative changes over time. Postcharacterization of these initial tests with skutterudite legs using a potential Seebeck microprobe and an electron microscope showed that oxidation and interlayer diffusion are the main reasons for the gradual increase in internal resistance and the decrease in open-circuit voltage. Although we only tested skutterudite material in this work, the method is fully capable of testing all kinds of material, metallization, and coating. It is thus a promising method for studying the relationship between failure modes and mechanisms of functionalized thermoelectric legs.

The effect of age and unilateral leg immobilization for 2 weeks on substrate utilization during moderate-intensity exercise in human skeletal muscle.

PubMed

Vigelsø, A; Gram, M; Dybboe, R; Kuhlman, A B; Prats, C; Greenhaff, P L; Constantin-Teodosiu, D; Birk, J B; Wojtaszewski, J F P; Dela, F; Helge, J W

2016-04-15

This study aimed to provide molecular insight into the differential effects of age and physical inactivity on the regulation of substrate metabolism during moderate-intensity exercise. Using the arteriovenous balance technique, we studied the effect of immobilization of one leg for 2 weeks on leg substrate utilization in young and older men during two-legged dynamic knee-extensor moderate-intensity exercise, as well as changes in key proteins in muscle metabolism before and after exercise. Age and immobilization did not affect relative carbohydrate and fat utilization during exercise, but the older men had higher uptake of exogenous fatty acids, whereas the young men relied more on endogenous fatty acids during exercise. Using a combined whole-leg and molecular approach, we provide evidence that both age and physical inactivity result in intramuscular lipid accumulation, but this occurs only in part through the same mechanisms. Age and inactivity have been associated with intramuscular triglyceride (IMTG) accumulation. Here, we attempt to disentangle these factors by studying the effect of 2 weeks of unilateral leg immobilization on substrate utilization across the legs during moderate-intensity exercise in young (n = 17; 23 ± 1 years old) and older men (n = 15; 68 ± 1 years old), while the contralateral leg served as the control. After immobilization, the participants performed two-legged isolated knee-extensor exercise at 20 ± 1 W (∼50% maximal work capacity) for 45 min with catheters inserted in the brachial artery and both femoral veins. Biopsy samples obtained from vastus lateralis muscles of both legs before and after exercise were used for analysis of substrates, protein content and enzyme activities. During exercise, leg substrate utilization (respiratory quotient) did not differ between groups or legs. Leg fatty acid uptake was greater in older than in young men, and although young men demonstrated net leg glycerol release during

Dominant side in single-leg stance stability during floor oscillations at various frequencies

PubMed Central

2014-01-01

Background We investigated lateral dominance in the postural stability of single-leg stance with anteroposterior floor oscillations at various frequencies. Methods Thirty adults maintained a single-leg stance on a force platform for 20 seconds per trial. Trials were performed with no oscillation (static condition) and with anteroposterior floor oscillations (2.5-cm amplitude) at six frequencies: 0.25, 0.5, 0.75, 1.0, 1.25 and 1.5 Hz (dynamic condition). A set of three trials was performed on each leg in each oscillation frequency in random order. The mean speed of the center of pressure in the anteroposterior direction (CoPap) was calculated as an index of postural stability, and frequency analysis of CoPap sway was performed. Footedness for carrying out mobilizing activities was assessed with a questionnaire. Results CoPap speed exponentially increased as oscillation frequency increased in both legs. The frequency analysis of CoPap showed a peak <0.3 Hz at no oscillation. The frequency components at 0.25-Hz oscillation included common components with no oscillation and those at 1.5-Hz oscillation showed the maximum amplitude among all conditions. Postural stability showed no significant difference between left- and right-leg stance at no oscillation and oscillations ≤1.25 Hz, but at 1.5-Hz oscillation was significantly higher in the right-leg stance than in the left-leg stance. For the lateral dominance of postural stability at individual levels, the lateral difference in postural stability at no oscillation was positively correlated with that at 0.25-Hz oscillation (r = 0.51) and negatively correlated with that at 1.5-Hz oscillation (r = -0.53). For 70% of subjects, the dominant side of postural stability was different at no oscillation and 1.5-Hz oscillation. In the subjects with left- or right-side dominance at no oscillation, 94% or 38% changed their dominant side at 1.5-Hz oscillation, with a significant difference between these percentages. In

Variation in energy expenditure among black-legged kittiwakes: Effects of activity-specific metabolic rates and activity budgets

USGS Publications Warehouse

Jodice, P.G.R.; Roby, D.D.; Suryan, R.M.; Irons, D.B.; Kaufman, A.M.; Turco, K.R.; Visser, G. Henk

2003-01-01

We sought to determine the effect of variation in time-activity budgets (TABs) and foraging behavior on energy expenditure rates of parent black-legged kittiwakes (Rissa tridactyla). We quantified TABs using direct observations of radio-tagged adults and simultaneously measured field metabolic rates (FMR) of these same individuals (n = 20) using the doubly labeled water technique. Estimated metabolic rates of kittiwakes attending their brood at the nest or loafing near the colony were similar (ca. 1.3 x basal metabolic rate [BMR]), although loafing during foraging trips was more costly (2.9 x BMR). Metabolic rates during commuting flight (7.3 x BMR) and prey-searching flight (6.2 x BMR) were similar, while metabolic rates during plunge diving were much higher (ca. 47 x BMR). The proportion of the measurement interval spent foraging had a positive effect on FMR (R2 = 0.68), while the combined proportion of time engaged in nest attendance and loafing near the colony had a negative effect on FMR (R2 = 0.72). Thus, more than two-thirds of the variation in kittiwake FMR could be explained by the allocation of time among various activities. The high energetic cost of plunge diving relative to straight flight and searching flight suggests that kittiwakes can optimize their foraging strategy under conditions of low food availability by commuting long distances to feed in areas where gross foraging efficiency is high.

The Role of Active Exploration of 3D Face Stimuli on Recognition Memory of Facial Information

ERIC Educational Resources Information Center

Liu, Chang Hong; Ward, James; Markall, Helena

2007-01-01

Research on face recognition has mainly relied on methods in which observers are relatively passive viewers of face stimuli. This study investigated whether active exploration of three-dimensional (3D) face stimuli could facilitate recognition memory. A standard recognition task and a sequential matching task were employed in a yoked design.…

Exercise motivation of college students in online, face-to-face, and blended basic studies physical activity and wellness course delivery formats.

PubMed

Sidman, Cara Lynn; Fiala, Kelly Ann; D'Abundo, Michelle Lee

2011-01-01

The purpose of this study was to assess exercise motivation among college students self-selected into 4 online (OL) and face-to-face (F2F) basic studies' physical activity and wellness course delivery formats. Out of 1,037 enrolled students during the Spring 2009 semester, 602 responded online to demographic questions and to the Behavioural Regulation in Exercise Questionnaire, which assessed exercise motivation on 5 subscales. There were no significant differences (p > .05) in exercise motivation for students across course delivery formats, but there was a significant difference in age and employment status between the completely OL and F2F course formats. Health and physical educators can utilize these findings to better understand that physical activity and wellness students are not necessarily trying to avoid physical activity when selecting the OL course format, but are more likely trying to balance work and school responsibilities and need greater flexibility in time and location.

Distant influences of amygdala lesion on visual cortical activation during emotional face processing.

PubMed

Vuilleumier, Patrik; Richardson, Mark P; Armony, Jorge L; Driver, Jon; Dolan, Raymond J

2004-11-01

Emotional visual stimuli evoke enhanced responses in the visual cortex. To test whether this reflects modulatory influences from the amygdala on sensory processing, we used event-related functional magnetic resonance imaging (fMRI) in human patients with medial temporal lobe sclerosis. Twenty-six patients with lesions in the amygdala, the hippocampus or both, plus 13 matched healthy controls, were shown pictures of fearful or neutral faces in task-releant or task-irrelevant positions on the display. All subjects showed increased fusiform cortex activation when the faces were in task-relevant positions. Both healthy individuals and those with hippocampal damage showed increased activation in the fusiform and occipital cortex when they were shown fearful faces, but this was not the case for individuals with damage to the amygdala, even though visual areas were structurally intact. The distant influence of the amygdala was also evidenced by the parametric relationship between amygdala damage and the level of emotional activation in the fusiform cortex. Our data show that combining the fMRI and lesion approaches can help reveal the source of functional modulatory influences between distant but interconnected brain regions.

Peripheral artery disease - legs

MedlinePlus

... flow, which can injure nerves and other tissues. Causes PAD is caused by "hardening of the arteries." ... small arteries Coronary artery disease Impotence Open sores (ischemic ulcers on the lower legs) Tissue death (gangrene) ...

Leg lengthening and shortening

MedlinePlus

... to match its length. Proper timing of this treatment is important for best results. Certain health conditions can lead to very unequal leg lengths. They include: Poliomyelitis Cerebral palsy Small, weak muscles or short, tight ( ...

Hip-Abductor Fatigue and Single-Leg Landing Mechanics in Women Athletes

PubMed Central

Patrek, Mary F.; Kernozek, Thomas W.; Willson, John D.; Wright, Glenn A.; Doberstein, Scott T.

2011-01-01

Abstract Context: Reduced hip-abductor strength and muscle activation may be associated with altered lower extremity mechanics, which are thought to increase the risk for anterior cruciate ligament injury. However, experimental evidence supporting this relationship is limited. Objective: To examine the changes in single-leg landing mechanics and gluteus medius recruitment that occur after a hip-abductor fatigue protocol. Design: Descriptive laboratory study. Patients or Other Participants: Twenty physically active women (age  =  21.0 ± 1.3 years). Intervention(s): Participants were tested before (prefatigue) and after (postfatigue) a hip-abductor fatigue protocol consisting of repetitive side-lying hip abduction. Main Outcome Measure(s): Outcome measures included sagittal-plane and frontal-plane hip and knee kinematics at initial contact and at 60 milliseconds after initial contact during 5 single-leg landings from a height of 40 cm. Peak hip and knee sagittal-plane and frontal-plane joint moments during this time interval were also analyzed. Measures of gluteus medius activation, including latency, peak amplitude, and integrated signal, were recorded. Results: A small (<1°) increase in hip-abduction angle at initial contact and a small (<1°) decrease in knee-abduction (valgus) angle at 60 milliseconds after contact were observed in the postfatigue landing condition. No other kinematic changes were noted for the knee or hip at initial contact or at 60 milliseconds after initial contact. Peak external knee-adduction moment decreased 27% and peak hip adduction moment decreased 24% during the postfatigue landing condition. Gluteus medius activation was delayed after the protocol, but no difference in peak or integrated signal was seen during the landing trials. Conclusions: Changes observed during single-leg landings after hip-abductor fatigue were not generally considered unfavorable to the integrity of the anterior cruciate ligament. Further work may be

Bionic ankle–foot prosthesis normalizes walking gait for persons with leg amputation

PubMed Central

Herr, Hugh M.; Grabowski, Alena M.

2012-01-01

Over time, leg prostheses have improved in design, but have been incapable of actively adapting to different walking velocities in a manner comparable to a biological limb. People with a leg amputation using such commercially available passive-elastic prostheses require significantly more metabolic energy to walk at the same velocities, prefer to walk slower and have abnormal biomechanics compared with non-amputees. A bionic prosthesis has been developed that emulates the function of a biological ankle during level-ground walking, specifically providing the net positive work required for a range of walking velocities. We compared metabolic energy costs, preferred velocities and biomechanical patterns of seven people with a unilateral transtibial amputation using the bionic prosthesis and using their own passive-elastic prosthesis to those of seven non-amputees during level-ground walking. Compared with using a passive-elastic prosthesis, using the bionic prosthesis decreased metabolic cost by 8 per cent, increased trailing prosthetic leg mechanical work by 57 per cent and decreased the leading biological leg mechanical work by 10 per cent, on average, across walking velocities of 0.75–1.75 m s−1 and increased preferred walking velocity by 23 per cent. Using the bionic prosthesis resulted in metabolic energy costs, preferred walking velocities and biomechanical patterns that were not significantly different from people without an amputation. PMID:21752817

LegC3, an Effector Protein from Legionella pneumophila, Inhibits Homotypic Yeast Vacuole Fusion In Vivo and In Vitro

PubMed Central

Bennett, Terry L.; Kraft, Shannon M.; Reaves, Barbara J.; Mima, Joji; O’Brien, Kevin M.; Starai, Vincent J.

2013-01-01

During infection, the intracellular pathogenic bacterium Legionella pneumophila causes an extensive remodeling of host membrane trafficking pathways, both in the construction of a replication-competent vacuole comprised of ER-derived vesicles and plasma membrane components, and in the inhibition of normal phagosome:endosome/lysosome fusion pathways. Here, we identify the LegC3 secreted effector protein from L. pneumophila as able to inhibit a SNARE- and Rab GTPase-dependent membrane fusion pathway in vitro, the homotypic fusion of yeast vacuoles (lysosomes). This vacuole fusion inhibition appeared to be specific, as similar secreted coiled-coiled domain containing proteins from L. pneumophila, LegC7/YlfA and LegC2/YlfB, did not inhibit vacuole fusion. The LegC3-mediated fusion inhibition was reversible by a yeast cytosolic extract, as well as by a purified soluble SNARE, Vam7p. LegC3 blocked the formation of trans-SNARE complexes during vacuole fusion, although we did not detect a direct interaction of LegC3 with the vacuolar SNARE protein complexes required for fusion. Additionally, LegC3 was incapable of inhibiting a defined synthetic model of vacuolar SNARE-driven membrane fusion, further suggesting that LegC3 does not directly inhibit the activity of vacuolar SNAREs, HOPS complex, or Sec17p/18p during membrane fusion. LegC3 is likely utilized by Legionella to modulate eukaryotic membrane fusion events during pathogenesis. PMID:23437241

Prevention of metabolic alterations caused by suspension hypokinesia in leg muscles of rats

NASA Technical Reports Server (NTRS)

Tischler, M. E.; Jaspers, S. R.; Fagan, J. M.

1983-01-01

Rats were subjected to tail-cast suspension hypokinesia for 6 days with one leg immobilized in dorsal flexion by casting. Control animals were also tail-casted. The soleus, gastrocnemius and plantaris muscles of uncasted hypokinetic legs were smaller than control muscles. Dorsal flexion prevented atrophy of these muscles and caused the soleus to hypertrophy. The anterior muscles were unaffected by hypokinesia. The smaller size of the soleus of the uncasted leg relative to the dorsal flexed and weight bearing limbs correlated with slower protein synthesis and faster proteolysis. The capacity of this muscle to synthesize glutamine (gln), which carries nitrogenous waste from muscle was also measured. Although tissue homogenates showed higher activities of gln synthetase, the rate of de novo synthesis was not altered in intact muscle but the tissue ratio of gln/glutamate was decreased. Glutamate and ATP were not limiting for gln synthesis, but availability of ammonia may be a limiting factor for this process in hypokinesia.

Static innominate asymmetry and leg length discrepancy in asymptomatic collegiate athletes.

PubMed

Krawiec, C J; Denegar, C R; Hertel, J; Salvaterra, G F; Buckley, W E

2003-11-01

The objectives of the study were to assess: (1) static innominate asymmetry in the sagittal plane, (2) leg length discrepancy (LLD), and (3) the relationship between static innominate rotation and LLD in asymptomatic collegiate athletes. The study was an observational study by design which took place in a University athletic training research laboratory. The participants were twenty-four male and 20 female asymptomatic intercollegiate athletes who volunteered to take part in the study. Static innominate asymmetry was assessed with a caliper/inclinometer tool and LLD was measured with a tape measure using standard clinical methods. Results showed that forty-two subjects (95%) demonstrated some degree of static innominate asymmetry. In 32 subjects (73%), the right innominate was more anteriorly rotated than the left. Nearly all subjects were determined to have unequal leg lengths with a majority, 30 subjects (68%), showing a slightly longer left leg. Weak correlations (r=0.33 - 0.44) were identified between static innominate asymmetry and LLD. In Conclusion static innominate asymmetry and LLD are common among asymptomatic collegiate athletes. This information provides clinicians with normative data of common clinical measures in a physically active population.

A system for evaluation and exercise-conditioning of paralyzed leg muscles.

PubMed

Gruner, J A; Glaser, R M; Feinberg, S D; Collins, S R; Nussbaum, N S

1983-07-01

The purpose of this project was to develop instrumentation and protocols in which electrical stimulation is used to induce exercise in paralyzed quadriceps muscles strength and endurance evaluation and conditioning. A computer-controlled electrical stimulation system, using surface electrodes, automatically regulates the bouts of leg extension exercise. Load weights attached just above the ankles can be progressively increased over a number of training sessions in such a manner that a measure of the fitness of the legs can be obtained. With three exercise sessions per week for 9 weeks, the strength and endurance of the quadriceps muscles of two paraplegic and four quadriplegic subjects were gradually and safely increased. During exercise at a means load weight of 5.4 kg, means heart rate did not rise above rest, whereas systolic blood pressure increased about 20 mm Hg, and skin temperature above the active muscles increased about 1.75 degrees C. Such exercise conditioning appears to be safe and may provide important health benefits, including improved fitness of the muscles and bones, better circulation in the paralyzed limbs, and enhanced self-image. Conditioned electrically stimulated paralyzed leg muscles may be used for locomotion in conjunction with special vehicles.

Quadrupedal gaits in hexapod animals - inter-leg coordination in free-walking adult stick insects.

PubMed

Grabowska, Martyna; Godlewska, Elzbieta; Schmidt, Joachim; Daun-Gruhn, Silvia

2012-12-15

The analysis of inter-leg coordination in insect walking is generally a study of six-legged locomotion. For decades, the stick insect Carausius morosus has been instrumental for unravelling the rules and mechanisms that control leg coordination in hexapeds. We analysed inter-leg coordination in C. morosus that freely walked on straight paths on plane surfaces with different slopes. Consecutive 1.7 s sections were assigned inter-leg coordination patterns (which we call gaits) based on footfall patterns. Regular gaits, i.e. wave, tetrapod or tripod gaits, occurred in different proportions depending on surface slopes. Tetrapod gaits were observed most frequently, wave gaits only occurred on 90 deg inclining slopes and tripod gaits occurred most often on 15 deg declining slopes, i.e. in 40% of the sections. Depending on the slope, 36-66% of the sections were assigned irregular gaits. Irregular gaits were mostly due to multiple stepping by the front legs, which is perhaps probing behaviour, not phase coupled to the middle legs' cycles. In irregular gaits, middle leg and hindleg coordination was regular, related to quadrupedal walk and wave gaits. Apparently, front legs uncouple from and couple to the walking system without compromising middle leg and hindleg coordination. In front leg amputees, the remaining legs were strictly coordinated. In hindleg and middle leg amputees, the front legs continued multiple stepping. The coordination of middle leg amputees was maladapted, with front legs and hindlegs performing multiple steps or ipsilateral legs being in simultaneous swing. Thus, afferent information from middle legs might be necessary for a regular hindleg stepping pattern.

Quality of nursing care from the perspective of patients with leg ulcers.

PubMed

Törnvall, E; Wilhelmsson, S

2010-09-01

To investigate and analyse the quality of nursing care in a primary care setting from the perspective of patients with leg ulcers and determine the subjective importance that patients attach to various aspects of quality of care. All of the patients with leg ulcers at 15 primary care centres in the south east of Sweden were invited to participate. They were given the short version of the Quality from the Patient's Perspective questionnaire (QPP) to fill in. This included a number of closed and open questions relating to their perceptions of the quality of their nursing care and the importance of this care to them. Overall, the patients in this study perceived that the quality of nursing care was high. However, important areas for improvement were revealed, including the need for an increase in patient-focused care, continuity of care and better pain relief. To address the weak points highlighted by the study, we recommend that nurses explore patient perceptions of pain in greater detail and invite patients take a more active role in the management of their leg ulcers.

Design of Force Sensor Leg for a Rocket Thrust Detector

NASA Astrophysics Data System (ADS)

Woten, Douglas; McGehee, Tripp; Wright, Anne

2005-03-01

A hybrid rocket is composed of a solid fuel and a separate liquid or gaseous oxidizer. These rockets may be throttled like liquid rockets, are safer than solid rockets, and are much less complex than liquid rockets. However, hybrid rockets produce thrust oscillations that are not practical for large scale use. A lab scale hybrid rocket at the University of Arkansas at Little Rock (UALR) Hybrid Rocket Facility is used to develop sensors to measure physical properties of hybrid rockets. Research is currently being conducted to design a six degree of freedom force sensor to measure the thrust and torque in all three spacial dimensions. The detector design uses six force sensor legs. Each leg utilizes strain gauges and a Wheatstone bridge to produce a voltage propotional to the force on the leg. The leg was designed using the CAD software ProEngineer and ProMechanica. Computer models of the strains on the single leg will be presented. A prototype leg was built and was tested in an INSTRON and results will be presented.

The effect of spinal manipulation on imbalances in leg strength.

PubMed

Chilibeck, Philip D; Cornish, Stephen M; Schulte, Al; Jantz, Nathan; Magnus, Charlene R A; Schwanbeck, Shane; Juurlink, Bernhard H J

2011-09-01

We hypothesized that spinal manipulation (SM) would reduce strength imbalances between legs. Using an un-blinded randomized design, 28 males and 21 females (54 ± 19y) with at least a 15% difference in isometric strength between legs for hip flexion, extension, abduction, or knee flexion were randomized to treatment or placebo (mock spinal manipulation). Strength of the stronger and weaker legs for hip flexion, extension, abduction, and/or knee flexion was assessed before and after the intervention. SM reduced the relative strength difference between legs for knee flexion (mean ± SD 57 ± 53 to 5 ± 14%) and hip flexion (24 ± 12 to 11 ± 15%) compared to placebo (34 ± 29 to 24 ± 36%, and 20 ± 18 to 22 ± 26%, respectively) (p = 0.05). SM also improved strength in the weak leg for hip abduction (104 ± 43 to 116 ± 43 Nm) compared to placebo (84 ± 24 to 85 ± 31 Nm) (p = 0.03). This study suggests that spinal manipulation may reduce imbalances in strength between legs for knee and hip flexion.

Kicking Back Cognitive Ageing: Leg Power Predicts Cognitive Ageing after Ten Years in Older Female Twins

PubMed Central

Steves, Claire J.; Mehta, Mitul M.; Jackson, Stephen H.D.; Spector, Tim D.

2016-01-01

Background Many observational studies have shown a protective effect of physical activity on cognitive ageing, but interventional studies have been less convincing. This may be due to short time scales of interventions, suboptimal interventional regimes or lack of lasting effect. Confounding through common genetic and developmental causes is also possible. Objectives We aimed to test whether muscle fitness (measured by leg power) could predict cognitive change in a healthy older population over a 10-year time interval, how this performed alongside other predictors of cognitive ageing, and whether this effect was confounded by factors shared by twins. In addition, we investigated whether differences in leg power were predictive of differences in brain structure and function after 12 years of follow-up in identical twin pairs. Methods A total of 324 healthy female twins (average age at baseline 55, range 43-73) performed the Cambridge Neuropsychological Test Automated Battery (CANTAB) at two time points 10 years apart. Linear regression modelling was used to assess the relationships between baseline leg power, physical activity and subsequent cognitive change, adjusting comprehensively for baseline covariates (including heart disease, diabetes, blood pressure, fasting blood glucose, lipids, diet, body habitus, smoking and alcohol habits, reading IQ, socioeconomic status and birthweight). A discordant twin approach was used to adjust for factors shared by twins. A subset of monozygotic pairs then underwent magnetic resonance imaging. The relationship between muscle fitness and brain structure and function was assessed using linear regression modelling and paired t tests. Results A striking protective relationship was found between muscle fitness (leg power) and both 10-year cognitive change [fully adjusted model standardised β-coefficient (Stdβ) = 0.174, p = 0.002] and subsequent total grey matter (Stdβ = 0.362, p = 0.005). These effects were robust in discordant

Kicking Back Cognitive Ageing: Leg Power Predicts Cognitive Ageing after Ten Years in Older Female Twins.

PubMed

Steves, Claire J; Mehta, Mitul M; Jackson, Stephen H D; Spector, Tim D

2016-01-01

Many observational studies have shown a protective effect of physical activity on cognitive ageing, but interventional studies have been less convincing. This may be due to short time scales of interventions, suboptimal interventional regimes or lack of lasting effect. Confounding through common genetic and developmental causes is also possible. We aimed to test whether muscle fitness (measured by leg power) could predict cognitive change in a healthy older population over a 10-year time interval, how this performed alongside other predictors of cognitive ageing, and whether this effect was confounded by factors shared by twins. In addition, we investigated whether differences in leg power were predictive of differences in brain structure and function after 12 years of follow-up in identical twin pairs. A total of 324 healthy female twins (average age at baseline 55, range 43-73) performed the Cambridge Neuropsychological Test Automated Battery (CANTAB) at two time points 10 years apart. Linear regression modelling was used to assess the relationships between baseline leg power, physical activity and subsequent cognitive change, adjusting comprehensively for baseline covariates (including heart disease, diabetes, blood pressure, fasting blood glucose, lipids, diet, body habitus, smoking and alcohol habits, reading IQ, socioeconomic status and birthweight). A discordant twin approach was used to adjust for factors shared by twins. A subset of monozygotic pairs then underwent magnetic resonance imaging. The relationship between muscle fitness and brain structure and function was assessed using linear regression modelling and paired t tests. A striking protective relationship was found between muscle fitness (leg power) and both 10-year cognitive change [fully adjusted model standardised β-coefficient (Stdβ) = 0.174, p = 0.002] and subsequent total grey matter (Stdβ = 0.362, p = 0.005). These effects were robust in discordant twin analyses, where within

FD115 (Flight Day 115) SPRINT leg muscle self scan

NASA Image and Video Library

2011-10-03

ISS029-E-025280 (3 Oct. 2011) --- NASA astronaut Mike Fossum, Expedition 29 commander, performs a SPRINT leg muscle self scan in the Columbus laboratory of the International Space Station. Fossum powered on the Ultrasound 2 (USND-2) unit and Video Power Converter (VPC) hardware, and connected the VPC to Human Research Facility 1 (HRF-1) in order to perform this activity.

FD115 (Flight Day 115) SPRINT leg muscle self scan

NASA Image and Video Library

2011-10-03

ISS029-E-025270 (3 Oct. 2011) --- NASA astronaut Mike Fossum, Expedition 29 commander, performs a SPRINT leg muscle self scan in the Columbus laboratory of the International Space Station. Fossum powered on the Ultrasound 2 (USND-2) unit and Video Power Converter (VPC) hardware, and connected the VPC to Human Research Facility 1 (HRF-1) in order to perform this activity.

Afterimage induced neural activity during emotional face perception.

PubMed

Cheal, Jenna L; Heisz, Jennifer J; Walsh, Jennifer A; Shedden, Judith M; Rutherford, M D

2014-02-26

The N170 response differs when positive versus negative facial expressions are viewed. This neural response could be associated with the perception of emotions, or some feature of the stimulus. We used an aftereffect paradigm to clarify. Consistent with previous reports of emotional aftereffects, a neutral face was more likely to be described as happy following a sad face adaptation, and more likely to be described as sad following a happy face adaptation. In addition, similar to previous observations with actual emotional faces, we found differences in the latency of the N170 elicited by the neutral face following sad versus happy face adaptation, demonstrating that the emotion-specific effect on the N170 emerges even when emotion expressions are perceptually different but physically identical. The re-entry of emotional information from other brain regions may be driving the emotional aftereffects and the N170 latency differences. Copyright © 2014 Elsevier B.V. All rights reserved.

Recognition memory of newly learned faces.

PubMed

Ishai, Alumit; Yago, Elena

2006-12-11

We used event-related fMRI to study recognition memory of newly learned faces. Caucasian subjects memorized unfamiliar, neutral and happy South Korean faces and 4 days later performed a memory retrieval task in the MR scanner. We predicted that previously seen faces would be recognized faster and more accurately and would elicit stronger neural activation than novel faces. Consistent with our hypothesis, novel faces were recognized more slowly and less accurately than previously seen faces. We found activation in a distributed cortical network that included face-responsive regions in the visual cortex, parietal and prefrontal regions, and the hippocampus. Within all regions, correctly recognized, previously seen faces evoked stronger activation than novel faces. Additionally, in parietal and prefrontal cortices, stronger activation was observed during correct than incorrect trials. Finally, in the hippocampus, false alarms to happy faces elicited stronger responses than false alarms to neutral faces. Our findings suggest that face recognition memory is mediated by stimulus-specific representations stored in extrastriate regions; parietal and prefrontal regions where old and new items are classified; and the hippocampus where veridical memory traces are recovered.

A springy pendulum could describe the swing leg kinetics of human walking.

PubMed

Song, Hyunggwi; Park, Heewon; Park, Sukyung

2016-06-14

The dynamics of human walking during various walking conditions could be qualitatively captured by the springy legged dynamics, which have been used as a theoretical framework for bipedal robotics applications. However, the spring-loaded inverted pendulum model describes the motion of the center of mass (CoM), which combines the torso, swing and stance legs together and does not explicitly inform us as to whether the inter-limb dynamics share the springy legged dynamics characteristics of the CoM. In this study, we examined whether the swing leg dynamics could also be represented by springy mechanics and whether the swing leg stiffness shows a dependence on gait speed, as has been observed in CoM mechanics during walking. The swing leg was modeled as a spring-loaded pendulum hinged at the hip joint, which is under forward motion. The model parameters of the loaded mass were adopted from body parameters and anthropometric tables, whereas the free model parameters for the rest length of the spring and its stiffness were estimated to best match the data for the swing leg joint forces. The joint forces of the swing leg were well represented by the springy pendulum model at various walking speeds with a regression coefficient of R(2)>0.8. The swing leg stiffness increased with walking speed and was correlated with the swing frequency, which is consistent with previous observations from CoM dynamics described using the compliant leg. These results suggest that the swing leg also shares the springy dynamics, and the compliant walking model could be extended to better present swing leg dynamics. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of Exercise Intensity on Percent Body Fat Determined by Leg-to-Leg and Segmental Bioelectrical Impedance Analyses in Adults

ERIC Educational Resources Information Center

Andreacci, Joseph L.; Nagle, Trisha; Fitzgerald, Elise; Rawson, Eric S.; Dixon, Curt B.

2013-01-01

Purpose: We examined the impact that cycle ergometry exercise had on percent body fat (%BF) estimates when assessed using either leg-to-leg or segmental bioelectrical impedance analysis (LBIA; SBIA) and whether the intensity of the exercise bout impacts the %BF magnitude of change. Method: Seventy-four college-aged adults participated in this…

Effects of acute psychosocial stress on neural activity to emotional and neutral faces in a face recognition memory paradigm.

PubMed

Li, Shijia; Weerda, Riklef; Milde, Christopher; Wolf, Oliver T; Thiel, Christiane M

2014-12-01

Previous studies have shown that acute psychosocial stress impairs recognition of declarative memory and that emotional material is especially sensitive to this effect. Animal studies suggest a central role of the amygdala which modulates memory processes in hippocampus, prefrontal cortex and other brain areas. We used functional magnetic resonance imaging (fMRI) to investigate neural correlates of stress-induced modulation of emotional recognition memory in humans. Twenty-seven healthy, right-handed, non-smoker male volunteers performed an emotional face recognition task. During encoding, participants were presented with 50 fearful and 50 neutral faces. One hour later, they underwent either a stress (Trier Social Stress Test) or a control procedure outside the scanner which was followed immediately by the recognition session inside the scanner, where participants had to discriminate between 100 old and 50 new faces. Stress increased salivary cortisol, blood pressure and pulse, and decreased the mood of participants but did not impact recognition memory. BOLD data during recognition revealed a stress condition by emotion interaction in the left inferior frontal gyrus and right hippocampus which was due to a stress-induced increase of neural activity to fearful and a decrease to neutral faces. Functional connectivity analyses revealed a stress-induced increase in coupling between the right amygdala and the right fusiform gyrus, when processing fearful as compared to neutral faces. Our results provide evidence that acute psychosocial stress affects medial temporal and frontal brain areas differentially for neutral and emotional items, with a stress-induced privileged processing of emotional stimuli.

Mean individual muscle activities and ratios of total muscle activities in a selective muscle strengthening experiment: the effects of lower limb muscle activity based on mediolateral slope angles during a one-leg stance.

PubMed

Lee, Sang-Yeol

2016-09-01

[Purpose] The purpose of this study was to provide basic data for research on selective muscle strengthening by identifying mean muscle activities and calculating muscle ratios for use in developing strengthening methods. [Subjects and Methods] Twenty-one healthy volunteers were included in this study. Muscle activity was measured during a one-leg stance under 6 conditions of slope angle: 0°, 5°, 10°, 15°, 20°, and 25°. The data used in the analysis were root mean square and % total muscle activity values. [Results] There were significant differences in the root mean square of the gluteus medius, the hamstring, and the medial gastrocnemius muscles. There were significant differences in % total muscle activity of the medial gastrocnemius. [Conclusion] Future studies aimed at developing selective muscle strengthening methods are likely to yield more effective results by using muscle activity ratios based on electromyography data.

Lower Leg Anterior and Lateral Intracompartmental Pressure Changes Before and After Classic Versus Skate Nordic Rollerskiing.

PubMed

Woods, Katherine M; Petron, David J; Shultz, Barry B; Hicks-Little, Charlie A

2015-08-01

Chronic exertional compartment syndrome (CECS) is a debilitating condition resulting in loss of function and a decrease in athletic performance. Cases of CECS are increasing among Nordic skiers; therefore, analysis of intracompartmental pressures (ICPs) before and after Nordic skiing is warranted. To determine if lower leg anterior and lateral ICPs and subjective lower leg pain levels increased after a 20-minute Nordic rollerskiing time trial and to examine if differences existed between postexercise ICPs for the 2 Nordic rollerskiing techniques, classic and skate. Crossover study. Outdoor paved loop. Seven healthy Division I Nordic skiers (3 men, 4 women; age = 22.71 ± 1.38 y, height = 175.36 ± 6.33 cm, mass = 70.71 ± 6.58 kg). Participants completed two 20-minute rollerskiing time trials using the classic and skate technique in random order. The time trials were completed 7 days apart. Anterior and lateral ICPs and lower leg pain scores were obtained at baseline and at minutes 1 and 5 after rollerskiing. Anterior and lateral ICPs (mm Hg) were measured using a Stryker Quic STIC handheld monitor. Subjective measures of lower leg pain were recorded using the 11-point Numeric Rating Scale. Increases in both anterior (P = .000) and lateral compartment (P = .002) ICPs were observed, regardless of rollerskiing technique used. Subjective lower leg pain increased after the classic technique for the men from baseline to 1 minute postexercise and after the skate technique for the women. Significant 3-way interactions (technique × time × sex) were observed for the anterior (P = .002) and lateral (P = .009) compartment ICPs and lower leg pain (P = .005). Postexercise anterior and lateral ICPs increased compared with preexercise ICPs after both classic and skate rollerskiing techniques. Lower leg pain is a primary symptom of CECS. The subjective lower leg pain 11-point Numeric Rating Scale results indicate that increases in lower leg ICPs sustained during Nordic

Trigger point-related sympathetic nerve activity in chronic sciatic leg pain: a case study.

PubMed

Skorupska, Elżbieta; Rychlik, Michał; Pawelec, Wiktoria; Bednarek, Agata; Samborski, Włodzimierz

2014-10-01

Sciatica has classically been associated with irritation of the sciatic nerve by the vertebral disc and consequent inflammation. Some authors suggest that active trigger points in the gluteus minimus muscle can refer pain in similar way to sciatica. Trigger point diagnosis is based on Travel and Simons criteria, but referred pain and twitch response are significant confirmatory signs of the diagnostic criteria. Although vasoconstriction in the area of a latent trigger point has been demonstrated, the vasomotor reaction of active trigger points has not been examined. We report the case of a 22-year-old Caucasian European man who presented with a 3-year history of chronic sciatic-type leg pain. In the third year of symptoms, coexistent myofascial pain syndrome was diagnosed. Acupuncture needle stimulation of active trigger points under infrared thermovisual camera showed a sudden short-term vasodilatation (an autonomic phenomenon) in the area of referred pain. The vasodilatation spread from 0.2 to 171.9 cm(2) and then gradually decreased. After needling, increases in average and maximum skin temperature were seen as follows: for the thigh, changes were +2.6°C (average) and +3.6°C (maximum); for the calf, changes were +0.9°C (average) and +1.4°C (maximum). It is not yet known whether the vasodilatation observed was evoked exclusively by dry needling of active trigger points. The complex condition of the patient suggests that other variables might have influenced the infrared thermovision camera results. We suggest that it is important to check if vasodilatation in the area of referred pain occurs in all patients with active trigger points. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Leg lengthening - series (image)

MedlinePlus

... as Legg-Perthes disease Previous injuries or bone fractures that may stimulate excessive bone growth Abnormal spinal ... in the bone to be lengthened; usually the lower leg bone (tibia) or upper ... small steps, usually over the course of several months.

Preschool negative emotionality predicts activity and connectivity of the fusiform face area and amygdala in later childhood.

PubMed

Kann, Sarah J; O'Rawe, Jonathan F; Huang, Anna S; Klein, Daniel N; Leung, Hoi-Chung

2017-09-01

Negative emotionality (NE) refers to individual differences in the propensity to experience and react with negative emotions and is associated with increased risk of psychological disorder. However, research on the neural bases of NE has focused almost exclusively on amygdala activity during emotional face processing. This study broadened this framework by examining the relationship between observed NE in early childhood and subsequent neural responses to emotional faces in both the amygdala and the fusiform face area (FFA) in a late childhood/early adolescent sample. Measures of NE were obtained from children at age 3 using laboratory observations, and functional magnetic resonance imaging (fMRI) data were collected when these children were between the ages of 9 and 12 while performing a visual stimulus identity matching task with houses and emotional faces as stimuli. Multiple regression analyses revealed that higher NE at age 3 is associated with significantly greater activation in the left amygdala and left FFA but lower functional connectivity between these two regions during the face conditions. These findings suggest that those with higher early NE have subsequent alterations in both activity and connectivity within an extended network during face processing. © The Author (2017). Published by Oxford University Press.

Leg ulceration as a long-term complication of deep vein thrombosis.

PubMed

Walker, Natalie; Rodgers, Anthony; Birchall, Nicholas; Norton, Robyn; MacMahon, Stephen

2003-12-01

To evaluate the role of deep vein thrombosis as a cause of leg ulcers. A population-based, case-control study was conducted in Central and North Auckland, New Zealand. Cases comprised 241 people aged 40 to 99 years and on the electoral roll, with current leg ulcers (all types). Cases were identified by means of notification from health professionals and by self-referral. Controls were 224 people in the same age group, without leg ulcers, who were selected from the electoral roll by using a stratified random sampling process. The occurrence of leg ulceration as a consequence of exposure to deep vein thrombosis or being at high risk of deep vein thrombosis (that is, people with a family history of deep vein thrombosis, and/or a history of leg fracture and/or hip, leg, or foot surgery). After adjustment for age, sex, and other potential confounding factors, people who had a diagnosed thromboembolism were at almost three times higher risk of having a leg ulcer (odds ratio, 2.92; 95% confidence interval (CI), 1.47 to 6.08). In addition, people who had been at high risk of a venous thrombosis but were not diagnosed with this condition (eg, people with a history of major leg surgery) were also at increased risk of ulceration (odds ratio, 2.25; 95% CI, 1.49-3.42). Overall, 56% (95% CI, 33% - 71%) of leg ulcers were attributed to being at high risk of deep vein thrombosis. Deep vein thrombosis and factors that place people at high risk of deep vein thrombosis are an important cause of leg ulcers in older people. This finding strengthens the rationale for the routine and long-term use of thromboprophylaxis, particularly in high-risk patients.

Multi-leg heat pipe evaporator

NASA Technical Reports Server (NTRS)

Alario, J. P.; Haslett, R. A. (Inventor)

1986-01-01

A multileg heat pipe evaporator facilitates the use and application of a monogroove heat pipe by providing an evaporation section which is compact in area and structurally more compatible with certain heat exchangers or heat input apparatus. The evaporation section of a monogroove heat pipe is formed by a series of parallel legs having a liquid and a vapor channel and a communicating capillary slot therebetween. The liquid and vapor channels and interconnecting capillary slots of the evaporating section are connected to the condensing section of the heat pipe by a manifold connecting liquid and vapor channels of the parallel evaporation section legs with the corresponding liquid and vapor channels of the condensing section.

Characterizing rapid-onset vasodilation to single muscle contractions in the human leg

PubMed Central

Credeur, Daniel P.; Holwerda, Seth W.; Restaino, Robert M.; King, Phillip M.; Crutcher, Kiera L.; Laughlin, M. Harold; Padilla, Jaume

2014-01-01

Rapid-onset vasodilation (ROV) following single muscle contractions has been examined in the forearm of humans, but has not yet been characterized in the leg. Given known vascular differences between the arm and leg, we sought to characterize ROV following single muscle contractions in the leg. Sixteen healthy men performed random ordered single contractions at 5, 10, 20, 40, and 60% of their maximum voluntary contraction (MVC) using isometric knee extension made with the leg above and below heart level, and these were compared with single isometric contractions of the forearm (handgrip). Single thigh cuff compressions (300 mmHg) were utilized to estimate the mechanical contribution to leg ROV. Continuous blood flow was determined by duplex-Doppler ultrasound and blood pressure via finger photoplethysmography (Finometer). Single isometric knee extensor contractions produced intensity-dependent increases in peak leg vascular conductance that were significantly greater than the forearm in both the above- and below-heart level positions (e.g., above heart level: leg 20% MVC, +138 ± 28% vs. arm 20% MVC, +89 ± 17%; P < 0.05). Thigh cuff compressions also produced a significant hyperemic response, but these were brief and smaller in magnitude compared with single isometric contractions in the leg. Collectively, these data demonstrate the presence of a rapid and robust vasodilation to single muscle contractions in the leg that is largely independent of mechanical factors, thus establishing the leg as a viable model to study ROV in humans. PMID:25539935

Rembrandt's 'Beggar with a wooden leg' and other comparable prints.

PubMed

ten Kate, J J; Jennekens, F G I; Vos-Niël, J M E

2009-02-01

Rembrandt's etching of a beggar with a wooden leg is notable because the two lower limbs of the presumed beggar are present and not deformed. Using the facilities of four specialised Dutch art institutes, we carried out a systematic investigation to find other etchings and engravings of subjects with artificial legs supporting non-amputated limbs, from the period 1500 to 1700 AD. We discovered 28 prints produced by at least 18 artists. Several offered clues to a disorder of a knee, the lower leg or the foot. All individuals were adult males, suggesting the probability of traumatic lesions. We conclude that in this period artificial legs were not only used in the case of absence of part of a lower limb, but also for other reasons, notably disorders of the knee, lower leg or foot. They may also have been used to attract compassion.

Acute Effects of Stretching on Leg and Vertical Stiffness During Treadmill Running.

PubMed

Pappas, Panagiotis T; Paradisis, Giorgos P; Exell, Timothy A; Smirniotou, Athanasia S; Tsolakis, Charilaos K; Arampatzis, Adamantios

2017-12-01

Pappas, PT, Paradisis, GP, Exell, TA, Smirniotou, AS, Tsolakis, CK, and Arampatzis, A. Acute effects of stretching on leg and vertical stiffness during treadmill running. J Strength Cond Res 31(12): 3417-3424, 2017-The implementation of static (SS) and dynamic (DS) stretching during warm-up routines produces significant changes in biological and functional properties of the human musculoskeletal system. These properties could affect the leg and vertical stiffness characteristics that are considered important factors for the success of athletic activities. The aim of this study was to investigate the influence of SS and DS on selected kinematic variables, and leg and vertical stiffness during treadmill running. Fourteen men (age: 22.58 ± 1.05 years, height: 1.77 ± 0.05 m, body mass: 72.74 ± 10.04 kg) performed 30-second running bouts at 4.44 m·s, under 3 different stretching conditions (SS, DS, and no stretching). The total duration in each stretching condition was 6 minutes, and each of the 4 muscle groups was stretched for 40 seconds. Leg and vertical stiffness values were calculated using the "sine wave" method, with no significant differences in stiffness found between stretching conditions. After DS, vertical ground reaction force increased by 1.7% (p < 0.05), which resulted in significant (p < 0.05) increases in flight time (5.8%), step length (2.2%), and vertical displacement of the center of mass (4.5%) and a decrease in step rate (2.2%). Practical durations of SS and DS stretching did not influence leg or vertical stiffness during treadmill running. However, DS seems to result in a small increase in lower-limb force production which may influence running mechanics.

Leg massage therapy promotes psychological relaxation and reinforces the first-line host defense in cancer patients.

PubMed

Noto, Yuka; Kitajima, Maiko; Kudo, Mihoko; Okudera, Koichi; Hirota, Kazuyoshi

2010-12-01

Patients with cancer suffer a wide range of physical symptoms coupled with psychological stress. Moreover, cancer chemotherapy induces immunosuppression and consequently causes respiratory infections. Massage therapy has been reported to reduce symptoms in cancer patients via an increase in psychosocial relaxation and to enhance and/or improve immune function. In the present study, we determined whether leg massage could induce psychosocial relaxation and activate the first line of the host defense system. To assess effects of rest and leg massage, 15 healthy volunteers rested on a bed for 20 min on the first day, and 3 days later the subjects received a standardized massage of the legs for 20 min with nonaromatic oil. Twenty-nine cancer patients also received the same standardized massage of the legs. Anxiety/stress was assessed before and just after the rest or the massage using the State-Trait Anxiety Inventory (STAI-s) and visual analogue scale (VAS). To evaluate oral immune function, salivary chromogranin A (CgA) and secretory immunoglobulin A (sIgA) levels were measured. In healthy volunteers, rest significantly reduced VAS by 34% and increased sIgA by 61%. In contrast, leg massage significantly reduced both STAI-s and VAS by 24% and 63%, and increased both sIgA and CgA by 104% and 90%, respectively. In cancer patients, leg massage significantly decreased both STAI-s and VAS by 16% and 38%, and increased both salivary CgA and sIgA by 33% and 35%, respectively. Leg massage may promote psychosocial relaxation and reinforce a first-line host defense with an increase in secretion of antimicrobial peptides.

Four weeks one-leg training and high fat diet does not alter PPARalpha protein or mRNA expression in human skeletal muscle.

PubMed

Helge, J W; Bentley, D; Schjerling, P; Willer, M; Gibala, M J; Franch, J; Tapia-Laliena, M A; Daugaard, J R; Andersen, J L

2007-09-01

Fatty acid metabolism is influenced by training and diet with exercise training mediating this through activation of nuclear hormone receptor peroxisome proliferator-activated receptor alpha (PPARalpha) in skeletal muscle. This study investigated the effect of training and high fat or normal diet on PPARalpha expression in human skeletal muscle. Thirteen men trained one leg (T) four weeks (31.5 h in total), while the other leg (UT) served as control. During the 4 weeks six subjects consumed high fat (FAT) diet and seven subjects maintained a normal (CHO) diet. Biopsies were obtained from vastus lateralis muscle in both legs before and after training. After the biopsy, one-leg extension exercise was performed in random order with both legs 30 min at 95% of workload max. A training effect was evident as citrate synthase activity increased (P < 0.05) by 15% in the trained, but not the control leg in both groups. During exercise respiratory exchange ratio was lower in FAT (0.86 +/- 0.01, 0.83 +/- 0.01, mean +/- SEM) than CHO (0.96 +/- 0.02, 0.94 +/- 0.03) and in UT than T legs, respectively. The PPARalpha protein (144 +/- 44, 104 +/- 28, 79 +/- 15, 79 +/- 14, % of pre level) and PPARalpha mRNA (69 +/- [2, 2], 78 +/- [7, 6], 92 +/- [22, 18], 106 +/- [21, 18], % of pre level, geometric mean +/- SEM) expression remained unchanged by diet and training in FAT (UT, T) and CHO (UT, T), respectively. After the training and diet CS, HAD, PPARalpha, UCP2, UCP3 and mFABP mRNA content remained unchanged, whereas GLUT4 mRNA was lower in both groups and LDHA mRNA was lower (P < 0.05) only in FAT. 4 weeks one leg knee extensor training did not affect PPARalpha protein or mRNA expression. Furthermore, higher fat oxidation during exercise after fat rich diet was not accompanied by an increased PPARalpha protein or mRNA expression after 4 weeks.

An Investigation of the Relationship Between fMRI and ERP Source Localized Measurements of Brain Activity during Face Processing

PubMed Central

Richards, Todd; Webb, Sara Jane; Murias, Michael; Merkle, Kristen; Kleinhans, Natalia M.; Johnson, L. Clark; Poliakov, Andrew; Aylward, Elizabeth; Dawson, Geraldine

2013-01-01

Brain activity patterns during face processing have been extensively explored with functional magnetic resonance imaging (fMRI) and event-related potentials (ERPs). ERP source localization adds a spatial dimension to the ERP time series recordings, which allows for a more direct comparison and integration with fMRI findings. The goals for this study were (1) to compare the spatial descriptions of neuronal activity during face processing obtained with fMRI and ERP source localization using low-resolution electro-magnetic tomography (LORETA), and (2) to use the combined information from source localization and fMRI to explore how the temporal sequence of brain activity during face processing is summarized in fMRI activation maps. fMRI and high-density ERP data were acquired in separate sessions for 17 healthy adult males for a face and object processing task. LORETA statistical maps for the comparison of viewing faces and viewing houses were coregistered and compared to fMRI statistical maps for the same conditions. The spatial locations of face processing-sensitive activity measured by fMRI and LORETA were found to overlap in a number of areas including the bilateral fusiform gyri, the right superior, middle and inferior temporal gyri, and the bilateral precuneus. Both the fMRI and LORETA solutions additionally demon-strated activity in regions that did not overlap. fMRI and LORETA statistical maps of face processing-sensitive brain activity were found to converge spatially primarily at LORETA solution latencies that were within 18 ms of the N170 latency. The combination of data from these techniques suggested that electrical brain activity at the latency of the N170 is highly represented in fMRI statistical maps. PMID:19322649

Running in the real world: adjusting leg stiffness for different surfaces

NASA Technical Reports Server (NTRS)

Ferris, D. P.; Louie, M.; Farley, C. T.

1998-01-01

A running animal coordinates the actions of many muscles, tendons, and ligaments in its leg so that the overall leg behaves like a single mechanical spring during ground contact. Experimental observations have revealed that an animal's leg stiffness is independent of both speed and gravity level, suggesting that it is dictated by inherent musculoskeletal properties. However, if leg stiffness was invariant, the biomechanics of running (e.g. peak ground reaction force and ground contact time) would change when an animal encountered different surfaces in the natural world. We found that human runners adjust their leg stiffness to accommodate changes in surface stiffness, allowing them to maintain similar running mechanics on different surfaces. These results provide important insight into mechanics and control of animal locomotion and suggest that incorporating an adjustable leg stiffness in the design of hopping and running robots is important if they are to match the agility and speed of animals on varied terrain.

[Physical treatment modalities for chronic leg ulcers].

PubMed

Dissemond, J

2010-05-01

An increasing numbers of physical treatment options are available for chronic leg ulcer. In this review article, compression therapy, therapeutic ultrasound, negative pressure therapy, extracorporeal shock wave therapy, electrostimulation therapy, electromagnetic therapy, photodynamic therapy, water-filtered infrared-A-radiation and hydrotherapy are discussed in terms of their practical applications and the underlying evidence. With the exception of compression therapy for most of these treatments, good scientific data are not available. However this is a widespread problem in the treatment of chronic wounds. Nevertheless, several of the described methods such as negative pressure therapy represent one of the gold standards in practical treatment of patients with chronic leg ulcers. Although the use of physical treatment modalities may improve healing in patients with chronic leg ulcers, the diagnosis and treatment of the underlying causes are essential for long-lasting success.

Effect of shoe insert construction on foot and leg movement.

PubMed

Nigg, B M; Khan, A; Fisher, V; Stefanyshyn, D

1998-04-01

The purpose of this study was to quantify changes in foot eversion and tibial rotation during running resulting from systematic changes of material composition of five shoe inserts of the same shape. Tests were performed with 12 subjects. The inserts had a bilayer design using two different materials at the top and bottom of the insert. The functional kinematic variables examined in this study were the foot-leg in-eversion angle, beta, and the leg-foot tibial rotation, rho. Additionally, the subject characteristics of arch height, relative arch deformation, and active range of motion were quantified. The statistical analysis used was a two way repeated measures MANOVA (within trials and inserts). The average group changes resulting from the studied inserts in total shoe eversion, total foot eversion, and total internal tibial rotation were typically smaller than 1 degree when compared with the no-insert condition and were statistically not significant. The measured ranges of total foot eversion for all subjects were smallest for the softest and about twice as large for the hardest insert construction. Thus, the soft insert construction was more restrictive, forcing all feet into a similar movement pattern, whereas the harder combinations allowed for more individual variation of foot and leg movement and did not force the foot into a preset movement pattern. The individual results showed substantial differences between subjects and a trend: Subjects who generally showed a reduction of tibial rotation with all tested inserts typically had a flexible foot. However, subjects who generally showed an increase of tibial rotation typically had a stiff foot. The results of this study suggest that subject specific factors such as static, dynamic, and neuro-physiological characteristics of foot and leg are important to match specific feet and shoe inserts optimally.

Comparable Neutrophil Responses for Arm and Intensity-matched Leg Exercise.

PubMed

Leicht, Christof A; Goosey-Tolfrey, Victoria L; Bishop, Nicolette C

2017-08-01

Arm exercise is performed at lower absolute intensities than lower body exercise. This may impact on intensity-dependent neutrophil responses, and it is unknown whether individuals restricted to arm exercise experience the same changes in the neutrophil response as found for lower body exercise. Therefore, we aimed to investigate the importance of exercise modality and relative exercise intensity on the neutrophil response. Twelve moderately trained men performed three 45-min constant load exercise trials after determination of peak oxygen uptake for arm exercise (V˙O2peak arms) and cycling (V˙O2peak legs): 1) arm cranking exercise at 60% V˙O2peak arms, 2) moderate cycling at 60% V˙O2peak legs, and 3) easy cycling at 60% V˙O2peak arms. Neutrophil numbers in the circulation increased for all exercise trials, but were significantly lower for easy cycling when compared with arm exercise (P = 0.009), mirroring the blunted increase in HR and epinephrine during easy cycling. For all trials, exercising HR explained some of the variation of the neutrophil number 2 h postexercise (R = 0.51-0.69), epinephrine explaining less of this variation (R = 0.21-0.34). The number of neutrophils expressing CXCR2 decreased in the recovery from exercise in all trials (P < 0.05). Arm and leg exercise elicits the same neutrophil response when performed at the same relative intensity, implying that populations restricted to arm exercise might achieve a similar exercise induced neutrophil response as those performing lower body exercise. A likely explanation for this is the higher sympathetic activation and cardiac output for arm and relative intensity-matched leg exercise when compared with easy cycling, which is partly reflected in HR. This study further shows that the downregulation of CXCR2 may be implicated in exercise-induced neutrophilia.

Successful Decoding of Famous Faces in the Fusiform Face Area

PubMed Central

Axelrod, Vadim; Yovel, Galit

2015-01-01

What are the neural mechanisms of face recognition? It is believed that the network of face-selective areas, which spans the occipital, temporal, and frontal cortices, is important in face recognition. A number of previous studies indeed reported that face identity could be discriminated based on patterns of multivoxel activity in the fusiform face area and the anterior temporal lobe. However, given the difficulty in localizing the face-selective area in the anterior temporal lobe, its role in face recognition is still unknown. Furthermore, previous studies limited their analysis to occipito-temporal regions without testing identity decoding in more anterior face-selective regions, such as the amygdala and prefrontal cortex. In the current high-resolution functional Magnetic Resonance Imaging study, we systematically examined the decoding of the identity of famous faces in the temporo-frontal network of face-selective and adjacent non-face-selective regions. A special focus has been put on the face-area in the anterior temporal lobe, which was reliably localized using an optimized scanning protocol. We found that face-identity could be discriminated above chance level only in the fusiform face area. Our results corroborate the role of the fusiform face area in face recognition. Future studies are needed to further explore the role of the more recently discovered anterior face-selective areas in face recognition. PMID:25714434

Successful decoding of famous faces in the fusiform face area.

PubMed

Axelrod, Vadim; Yovel, Galit

2015-01-01

What are the neural mechanisms of face recognition? It is believed that the network of face-selective areas, which spans the occipital, temporal, and frontal cortices, is important in face recognition. A number of previous studies indeed reported that face identity could be discriminated based on patterns of multivoxel activity in the fusiform face area and the anterior temporal lobe. However, given the difficulty in localizing the face-selective area in the anterior temporal lobe, its role in face recognition is still unknown. Furthermore, previous studies limited their analysis to occipito-temporal regions without testing identity decoding in more anterior face-selective regions, such as the amygdala and prefrontal cortex. In the current high-resolution functional Magnetic Resonance Imaging study, we systematically examined the decoding of the identity of famous faces in the temporo-frontal network of face-selective and adjacent non-face-selective regions. A special focus has been put on the face-area in the anterior temporal lobe, which was reliably localized using an optimized scanning protocol. We found that face-identity could be discriminated above chance level only in the fusiform face area. Our results corroborate the role of the fusiform face area in face recognition. Future studies are needed to further explore the role of the more recently discovered anterior face-selective areas in face recognition.

Bilateral asymmetries in max effort single-leg vertical jumps.

PubMed

Stephens, Thomas M; Lawson, Brooke R; Reiser, Raoul F

2005-01-01

While asymmetries in the lower extremity during jumping may have implications during rehabilitation, it is not clear if healthy subjects should be expected to jump equivalently on each leg. Therefore, the goal of this study was to determine if asymmetries exist in maximal effort single-leg vertical jumps. After obtaining university-approved informed consent, 13 men and 12 women with competitive volleyball playing experience and no injuries of the lower-extremity that would predispose them to asymmetries participated. After thorough warm-up, five maximal effort vertical jumps with countermovement were performed on each leg (random order) with ground reaction forces and lower extremity kinematics recorded. The best three jumps from each leg were analyzed, assigning the leg with the highest jump height average as the dominant side. Asymmetry was assessed by determining statistical significance in the dominant versus non-dominant sides (p < 0.05). A significant interaction existed between side and gender for thigh length and peak vertical ground reaction force. Women had a significantly shorter thigh and men a greater peak vertical ground reaction force on their dominant side. All other parameters were assessed as whole group. Jumps were significantly greater off the dominant leg (2.8 cm on average). No other differences between sides were observed. Significant differences in magnitude (p < 0.05) existed between the men and women in jump height, several anthropometric parameters, minimum ankle and hip angles, and vertical ground reaction forces (peak and average). In conclusion, though a person may jump slightly higher on one leg relative to the other, and women may jump slightly differently than men, the magnitude of the difference should be relatively small and due to the multi-factorial nature of jump performance, individual parameters related to performance may not be consistently different.

Distal muscle activity alterations during the stance phase of gait in restless leg syndrome (RLS) patients.

PubMed

Dafkin, Chloe; Green, Andrew; Olivier, Benita; McKinon, Warrick; Kerr, Samantha

2018-05-01

To assess if there is a circadian variation in electromyographical (EMG) muscle activity during gait in restless legs syndrome (RLS) patients and healthy control participants. Gait assessment was done in 14 RLS patients and 13 healthy control participants in the evening (PM) and the morning (AM). Muscle activity was recorded bilaterally from the tibialis anterior (TA), lateral gastrocnemius (GL), rectus femoris (RF) and biceps femoris (BF) muscles. A circadian variation during the stance phase in only TA (PM > AM, p < 0.005) and BF (PM < AM, p = 0.008) activity was observed in control participants. Conversely no circadian variation was seen in any muscles in the RLS patients. RLS patients had an increased TA and GL activity (RLS > Controls, p < 0.05) during early stance and decreased GL activity (RLS < Controls, p < 0.01) during terminal stance in comparison to control participants in the evening. No other significant differences were noted between RLS patients and control participants. Activation of GL during the swing phase was noted in 79% of RLS patients and in 23% of control participants in the morning compared to 71% and 38% in the evening, respectively. EMG muscle activity shows no circadian variation in RLS patients. Evening differences in gait muscle activation patterns between RLS patients and control participants are evident. These results extend our knowledge about alterations in spinal processing during gait in RLS. A possible explanation for these findings is central pattern generator sensitization caused by increased sensitivity in cutaneous afferents in RLS patients. Copyright © 2018 Elsevier B.V. All rights reserved.

Arm to leg coordination in elite butterfly swimmers.

PubMed

Chollet, D; Seifert, L; Boulesteix, L; Carter, M

2006-04-01

This study proposed the use of four time gaps to assess arm-to-leg coordination in the butterfly stroke at increasing race paces. Fourteen elite male swimmers swam at four velocities corresponding to the appropriate paces for, respectively, the 400-m, 200-m, 100-m, and 50-m events. The different stroke phases of the arm and leg were identified by video analysis and then used to calculate four time gaps (T1: time gap between entry of the hands in the water and the high break-even point of the first undulation; T2: time gap between the beginning of the hands' backward movement and the low break-even point of the first undulation; T3: time gap between the hands' arrival in a vertical plane to the shoulders and the high break-even point of the second undulation; T4: time gap between the hands' release from the water and the low break-even point of the second undulation), the values of which described the changing relationship of arm to leg movements over an entire stroke cycle. With increases in pace, elite swimmers increased the stroke rate, the relative duration of the arm pull, the recovery and the first downward movement of the legs, and decreased the stroke length, the relative duration of the arm catch phase and the body glide with arms forward (measured by T2), until continuity in the propulsive actions was achieved. Whatever the paces, the T1, T3, and T4 values were close to zero and revealed a high degree of synchronisation at key motor points of the arm and leg actions. This new method to assess butterfly coordination could facilitate learning and coaching by situating the place of the leg undulation in relation with the arm stroke.

Do oarsmen have asymmetries in the strength of their back and leg muscles?

PubMed

Parkin, S; Nowicky, A V; Rutherford, O M; McGregor, A H

2001-07-01

The aim of this study was to establish whether asymmetry of the strength of the leg and trunk musculature is more prominent in rowers than in controls. Nineteen oarsmen and 20 male controls matched for age, height and body mass performed a series of isokinetic and isometric strength tests on an isokinetic dynamometer. These strength tests focused on the trunk and leg muscles. Comparisons of strength were made between and within groups for right and left symmetry patterns, hamstring: quadriceps ratios, and trunk flexor and extensor ratios. The results revealed no left and right asymmetries in either the knee extensor or flexor strength parameters (including both isometric and isokinetic measures). Knee extensor strength was significantly greater in the rowing population, but knee flexor strength was similar between the two groups. No difference was seen between the groups for the hamstring: quadriceps strength ratio. In the rowing population, stroke side had no influence on leg strength. No differences were observed in the isometric strength of the trunk flexors and extensors between groups, although EMG activity was significantly higher in the rowing population. Patterns of asymmetry of muscle activity were observed between the left and right erector spinae muscles during extension, which was significantly related to rowing side (P < 0.01). These observations could be related to the high incidence of low back pain in oarsmen.

Determination of muscle mass changes in legs from K-40 measurements

NASA Technical Reports Server (NTRS)

Palmer, H. E.; Rieksts, G. A.

1979-01-01

The K-40 content of the upper legs was periodically measured in several subjects whose injured legs had been in a cast for 6 weeks or more. As the subjects began using the leg again, the K-40 content increased as the muscle tissue was replaced. A 25% increase in K-40 content in 6 months is typical for a normal leg use and recovery. This is equivalent to an original muscle mass loss of 20%. By measuring specific body regions, such as arms or legs, with a high-efficiency detector system, muscle mass changes which exceed a few percent can be measured. These methods could be used in space flight and bedrest studies, and in studying nutritional deficiencies due to disease or diet.

The crossed leg sign indicates a favorable outcome after severe stroke

PubMed Central

Rémi, J.; Pfefferkorn, T.; Owens, R.L.; Schankin, C.; Dehning, S.; Birnbaum, T.; Bender, A.; Klein, M.; Adamec, J.; Pfister, H.-W.; Straube, A.

2011-01-01

Objective: We investigated whether crossed legs are a prognostic marker in patients with severe stroke. Methods: In this controlled prospective observational study, we observed patients with severe stroke who crossed their legs during their hospital stay and matched them with randomly selected severe stroke patients who did not cross their legs. The patients were evaluated upon admission, on the day of leg crossing, upon discharge, and at 1 year after discharge. The Glasgow Coma Scale, the NIH Stroke Scale (NIHSS), the modified Rankin Scale (mRS), and the Barthel Index (BI) were obtained. Results: Patients who crossed their legs (n = 34) and matched controls (n = 34) did not differ in any scale upon admission. At the time of discharge, the GCS did not differ, but the NIHSS was better in crossed legs patients (6.5 vs 10.6; p = 0.0026), as was the mRS (3.4 vs 5.1, p < 0.001), and the BI (34.0 vs 21.1; p = 0.0073). At 1-year follow-up, mRS (2.9 vs 5.1, p < 0.001) and the BI (71.3 vs 49.2; p = 0.045) were also better in the crossed leg group. The mortality between the groups differed grossly; only 1 patient died in the crossing group compared to 18 in the noncrossing group (p < 0.001). Conclusion: Leg crossing is an easily obtained clinical sign and is independent of additional technical examinations. Leg crossing within the first 15 days after severe stroke indicates a favorable outcome which includes less neurologic deficits, better independence in daily life, and lower rates of death. PMID:21987641

The relationship of hip muscle performance to leg, ankle and foot injuries: a systematic review.

PubMed

Steinberg, Nili; Dar, Gali; Dunlop, Martin; Gaida, James Edmund

2017-02-01

Hip control affects movement and muscle firing patterns in the leg, ankle and foot, and may contribute to overuse injuries. Muscle performance can be measured as strength, endurance or muscle activation patterns. Our objective was to systematically review whether hip muscle performance is associated with leg, ankle and foot injuries. A structured and comprehensive search of six medical literature databases was combined with forward and backward citation tracking (AMED, CINAHL, EMBASE, Medline, Scopus and SportDiscus). Eligible studies measured hip muscle performance in individuals with musculoskeletal injuries below the tibial tuberosity, using dynamometry or electromyography (EMG). All studies compared an injured group with a control group or compared the injured and non-injured limb in the same individual. Data was extracted from each study independently by two authors. Twenty case-control and four prospective studies (n = 24) met the inclusion criteria. Injury classifications included chronic ankle instability (n = 18), Achilles tendinopathy (n = 2), medial tibial stress syndrome and tibial stress fracture (n = 1), posterior tibial tendon dysfunction (n = 1), and exertional medial tibial pain (n = 2). Eleven of the studies revealed differences in hip muscle performance indicating less strength, delayed onset activation and decreased duration of activation in the injured groups. Two studies found evidence for differences between groups only in some of their measurements. Three out of the four prospective studies revealed that hip muscle performance was not a risk factor for leg, ankle and foot injuries. This review provides limited evidence that hip muscle performance variables are related to leg, ankle and foot injuries. Emerging evidence indicates this might be a result of the injury rather than a contributor to the injury.

Leg injuries and wound repair among cosmetid harvestmen (Arachnida, Opiliones, Laniatores).

PubMed

Townsend, Victor R; Schaus, Maynard H; Zvonareva, Tatyana; Illinik, Jeffrey J; Evans, John T

2017-01-01

Previous studies of leg injuries in harvestmen have focused on the fitness consequences for individuals that use autospasy (voluntary detachment of the leg) as a secondary defense mechanism. Leg damage among non-autotomizing species of laniatorean harvestmen has not been investigated. Under laboratory conditions, we damaged femur IV of Cynorta marginalis and observed with scanning electron microscopy (SEM) the changes in these wounds over ten days. We also used SEM to examine leg damage from individuals of three species of cosmetid harvestmen that were collected in the field. On the basis of changes in the external surface of the hemolymph coagulum, we classified these wounds as fresh (coagulum forming), recent (coagulum with smooth surface), older (coagulum is scale-like with visible cell fragments), and fully healed (scale replaced by new cuticle growth on the terminal stump). Our observations indicate that wound healing in harvestmen occurs in a manner comparable to that of other chelicerates. Leg injuries exhibited interspecific variation with respect to the overall frequency of leg wounds and the specific legs that were most commonly damaged. In addition, we measured walking and climbing speeds of adult C. marginalis and found that individuals with fresh injuries (lab-induced) to femur IV walked at speeds significantly slower than uninjured adults or individuals collected from the field that had fully healed wounds to a single leg. J. Morphol. 278:73-88, 2017. ©© 2016 Wiley Periodicals,Inc. © 2016 Wiley Periodicals, Inc.

[Cross replantation in a case of bilateral amputation of the legs].

PubMed

Girot, J; Marin-Braun, F; Merle, M; Xenard, J

1988-01-01

A case is reported of a patient aged 32 years who suffered bilateral traumatic amputation of the legs by a wagon. Neither of his two feet could be re-implanted to its original site. In spite of the severity of the lesions, reconstructive surgery was attempted by crossed re-implantation of the right foot onto the stump of the left leg. After bony shortening by 20 cm and internal fixation of the tibia, revascularisation was achieved by suture of the posterior tibial vascular pedicle. Primary repair of the posterior tibial nerve allowed protective sensibility to recover in the sole of the foot. Secondarily, a free musculo-cutaneous graft from the latissimus dorsi improved skin cover. Bony union occurred after 10 months. Prolonged rehabilitation resulted in satisfactory walking and activities of daily living and a return to work 18 months after the accident.

False memory for face in short-term memory and neural activity in human amygdala.

PubMed

Iidaka, Tetsuya; Harada, Tokiko; Sadato, Norihiro

2014-12-03

Human memory is often inaccurate. Similar to words and figures, new faces are often recognized as seen or studied items in long- and short-term memory tests; however, the neural mechanisms underlying this false memory remain elusive. In a previous fMRI study using morphed faces and a standard false memory paradigm, we found that there was a U-shaped response curve of the amygdala to old, new, and lure items. This indicates that the amygdala is more active in response to items that are salient (hit and correct rejection) compared to items that are less salient (false alarm), in terms of memory retrieval. In the present fMRI study, we determined whether the false memory for faces occurs within the short-term memory range (a few seconds), and assessed which neural correlates are involved in veridical and illusory memories. Nineteen healthy participants were scanned by 3T MRI during a short-term memory task using morphed faces. The behavioral results indicated that the occurrence of false memories was within the short-term range. We found that the amygdala displayed a U-shaped response curve to memory items, similar to those observed in our previous study. These results suggest that the amygdala plays a common role in both long- and short-term false memory for faces. We made the following conclusions: First, the amygdala is involved in detecting the saliency of items, in addition to fear, and supports goal-oriented behavior by modulating memory. Second, amygdala activity and response time might be related with a subject's response criterion for similar faces. Copyright © 2014 Elsevier B.V. All rights reserved.

Lower Extremity Limb Salvage with Cross Leg Pedicle Flap, Cross Leg Free Flap, and Cross Leg Vascular Cable Bridge Flap.

PubMed

Manrique, Oscar J; Bishop, Sarah N; Ciudad, Pedro; Adabi, Kian; Martinez-Jorge, Jorys; Moran, Steven L; Huang, Tony; Vijayasekaran, Aparna; Chen, Shih-Heng; Chen, Hung-Chi

2018-05-16

 Lower extremity salvage following significant soft tissue loss can be complicated by lack of recipient vessel for free tissue transfer. We describe our experience in lower limb salvage for patients with no recipient vessels with the use of pedicle, free and cable bridge flaps.  A retrospective review from 1985 to 2017 of patients undergoing lower limb salvage using a contralateral pedicle cross leg (PCL) flaps, free cross leg (FCL) flaps, or free cable bridge (FCB) flaps was conducted. Demographics, etiology of the reconstruction, type of flap used, donor-site vessels, defect size, operating time, time of pedicle division, length of hospital stay, time to ambulation, and complications were analyzed.  A total of 53 patients (48 males and 5 females) with an average age of 35 years (range, 29-38 years) were identified. The etiology for the reconstruction was trauma in 52 patients and oncological resection in 1 patient. There were 18 PCL, 25 FCL, and 10 FCB completed. The recipient vessels for all flaps were the posterior tibial artery and vein. The average operating room times for PCL, FCL, and FCB flaps were 4, 9, and 10 hours, respectively. The average length of hospital stay was 5 weeks and average time to ambulation was 4 weeks. The average follow-up time was 7.5 years (range, 3-12 years). Complications encountered were hematoma (six), prolonged pain (six), total flap loss (two), reoperation (five), and infection (four). Limb salvage rates were 96.2%.  When ipsilateral limb vessels are not available, and other reconstructive options have been exhausted, cross leg flaps can be a viable option for limb salvage in the setting of extensive defects. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Roll type conducting polymer legs for rigid-flexible thermoelectric generator

NASA Astrophysics Data System (ADS)

Park, Teahoon; Lim, Hanwhuy; Hwang, Jong Un; Na, Jongbeom; Lee, Hyunki; Kim, Eunkyoung

2017-07-01

A roll-type conducting polymer film was explored as a flexible organic p-type thermoelectric leg using poly(3,4-ethylenedioxythiophene) (PEDOT) doped with tosylate. The PEDOT films were prepared through solution casting polymerization and rolled up for a roll-type leg. Due to the high flexibility, the roll-type PEDOT leg enabled easy contact to both top and bottom electrodes. Simulation on the dynamic heat transfer and convective cooling for a vertically roosted rod- and roll-type PEDOT leg showed that the temperature difference (ΔT) between the hot and cold sides of the leg was much higher in the roll than that of the rod. The PEDOT legs were integrated with n-type Bi2Te3 blocks, to give a 36-couple rigid-flexible thermoelectric generator (RF-TEG). The maximum output voltage from the 36-couple RF-TEG under a ΔT of 7.9 K was determined as 36.7 mV along with a high output power of 115 nW. A wearable RF-TEG was prepared upon the combination of the 36-couple RF-TEG with an arm warmer, to afford an output voltage of 10.6 mV, which was generated constantly and steadily from human wrist heat.

The susceptibility of the knee extensors to eccentric exercise-induced muscle damage is not affected by leg dominance but by exercise order.

PubMed

Hody, S; Rogister, B; Leprince, P; Laglaine, T; Croisier, J-L

2013-09-01

The aims of this study were first to compare the response of dominant and non-dominant legs to eccentric exercise and second, to examine whether there is an effect of exercise order on the magnitude of symptoms associated with intense eccentric protocols. Eighteen young men performed three sets of 30 maximal eccentric isokinetic (60° s(-1)) contractions of the knee extensors (range of motion, ROM: 0°-100°, 0 = full extension) using either dominant or non-dominant leg. They repeated a similar eccentric bout using the contralateral leg 6 weeks later. The sequence of leg's use was allocated to create equally balanced groups. Four indirect markers of muscle damage including subjective pain intensity, maximal isometric strength, muscle stiffness and plasma creatine kinase (CK) activity were measured before and 24 h after exercise. All markers changed significantly following the eccentric bout performed either by dominant or non-dominant legs, but no significant difference was observed between legs. Interestingly, the comparison between the first and second eccentric bouts revealed that muscle soreness (-42%, P<0.001), CK activity (-62%, P<0.05) and strength loss (-54%, P<0.01) were significantly lower after the second bout. This study suggests that leg dominance does not influence the magnitude of exercise-induced muscle damage and supports for the first time the existence of a contralateral protection against exercise-induced muscle damage in the lower limbs. © 2013 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

Effects of Mobile Phone Usage in Supporting Leg Lymphedema Self-care

PubMed Central

Okutsu, Ayako; Koiyabashi, Kikuyo

2014-01-01

Objective: The aim of this study was to implement self-care support for leg lymphedema patients using mobile phones and to investigate the effects thereof. Patients and Methods: A total of 30 patients with lymphedema following female genital cancer surgery (stages I to II) who were referred from a nearby gynecologist were randomly divided into groups for routine self-care support (control group) and mobile telephone-assisted support (intervention group) and received the self-care support appropriate to their group. The (total) circumference of the leg with edema, FACT-G (cancer patient QOL), MHP (mental health status), and self-care self-assessment were comparatively investigated at three months after the initial interview. Results: No significant reduction in the (total) circumferences of legs with edema was confirmed in either the control or intervention group. The intervention group was significantly better than the control group in terms of the activity circumstances and FACT-G mental status at three months after the initial interview. The intervention group was also significantly better in psychological, social, and physical items in the MHP. The intervention group was significantly better than the control group in terms of circumstances of self-care implementation at three months after the initial interview. Additionally, comparison of the circumstances of implementation for different aspects of self-care content showed that the intervention group was significantly better at selecting shoes, observing edema, moisturizing, self-drainage, wearing compression garments, and implementing bandaging. Conclusion: Compared with routine self-care support, mobile telephone-assisted support is suggested to be effective for leg lymphedema patients’ QOL and mental health status as well as their self-care behaviors. PMID:25648778

Leg symptoms associated with sacroiliac joint disorder and related pain.

PubMed

Murakami, Eiichi; Aizawa, Toshimi; Kurosawa, Daisuke; Noguchi, Kyoko

2017-06-01

The symptoms of sacroiliac joint (SIJ) disorders are usually detected in the buttock and groin, and occasionally referred to the thigh and leg. However, lumbar disorders also cause symptoms in these same body regions. The presence of a characteristic, symptomatic pattern in the legs would be useful for diagnosing SIJ disorders. This study aimed to identify specific leg symptoms in patients with SIJ pain originating from the posterior sacroiliac ligament and determine the rate of occurrence of these symptoms. The source population consisted of 365 consecutive patients from February 2005 to December 2007. One hundred patients were diagnosed with SIJ pain by a periarticular SIJ injection (42 males and 58 females, average age 46 years, age range, 18-75 years). A leg symptom map was made by subtracting the symptoms after a periarticular SIJ injection from the initial symptoms, and evaluating the rate of each individual symptom by area. Ninety-four patients reported pain at or around the posterior-superior iliac spine (PSIS). Leg symptoms comprised pain and a numbness/tingling sensation; ≥60% of the patients had these symptoms. Pain was mainly detected in the back, buttock, groin, and thigh areas, while numbness/tingling was mainly detected in the lateral to posterior thigh and back of the calf. Leg symptoms associated with SIJ pain originating from the posterior sacroiliac ligament include both pain and numbness, which do not usually correspond to the dermatome. These leg symptoms in addition to pain around the PSIS may indicate SIJ disorders. Copyright © 2017 Elsevier B.V. All rights reserved.

On the design of a DEA-based device to pot entially assist lower leg disorders: an analytical and FEM investigation accounting for nonlinearities of the leg and device deformations.

PubMed

Pourazadi, Shahram; Ahmadi, Sadegh; Menon, Carlo

2015-11-05

One of the recommended treatments for disorders associated with the lower extremity venous insufficiency is the application of external mechanical compression. Compression stockings and elastic bandages are widely used for the purpose of compression therapy and are usually designed to exert a specified value or range of compression on the leg. However, the leg deforms under external compression, which can lead to undesirable variations in the amount of compression applied by the compression bandages. In this paper, the use of an active compression bandage (ACB), whose compression can be regulated through an electrical signal, is investigated. The ACB is based on the use of dielectric elastomer actuators. This paper specifically investigates, via both analytical and non-linear numerical simulations, the potential pressure the ACB can apply when the compliancy of the human leg is taken into account. The work underpins the need to account for the compressibility of the leg when designing compression garments for lower extremity venous insufficiency. A mathematical model is used to simulate the volumetric change of a calf when compressed. Suitable parameters for this calf model are selected from the literature where the calf, from ankle to knee, is divided into six different regions. An analytical electromechanical model of the ACB, which considers its compliancy as a function of its pre-stretch and electricity applied, is used to predict the ACB's behavior. Based on these calf and ACB analytical models, a simulation is performed to investigate the interaction between the ACB and the human calf with and without an electrical stimulus applied to the ACB. This simulation is validated by non-linear analysis performed using a software based on the finite element method (FEM). In all simulations, the ACB's elastomer is stretched to a value in the range between 140 and 220 % of its initial length. Using data from the literature, the human calf model, which is examined in

Leg raise increases pressure in lower and upper esophageal sphincter among patients with gastroesophageal reflux disease.

PubMed

Bitnar, P; Stovicek, J; Andel, R; Arlt, J; Arltova, M; Smejkal, M; Kolar, P; Kobesova, A

2016-07-01

The purpose of this study was to determine the relation between posturally increased intra-abdominal pressure and lower/upper esophageal sphincter pressure changes in patients with gastroesophageal reflux disease. We used high resolution manometry to measure pressure changes in lower and upper esophageal sphincter during bilateral leg rise. We also examined whether the rate of lower and upper esophageal sphincter pressure would increase during leg raise differentially in individuals with versus without normal resting pressure. Fifty eight patients with gastroesophageal reflux disease participated in the study. High resolution manometry was performed in relaxed supine position, then lower and upper esophageal sphincter pressure was measured. Finally, the subjects were instructed to keep their legs lifted while performing 90-degree flexion at the hips and knees and the pressure was measured again. Paired t-test and independent samples t-test were used. There was a significant increase in both lower (P < 0.001) and upper esophageal sphincter pressure (P = 0.034) during leg raise compared to the initial resting position. Individuals with initially higher pressure in lower esophageal sphincter (>10 mmHg) exhibited a greater pressure increase during leg raise than those with initially lower pressure (pressure ≤10 mmHg; P = 0.002). Similarly individuals with higher resting upper esophageal sphincter pressure (>44 mmHg) showed a greater pressure increase during leg raise than those with lower resting pressure (≤44 mmHg; P < 0.001). The results illustrate the influence of postural leg activities on intraesophageal pressure in patients with gastroesophageal reflux disease, indicating by means of high resolution manometry that diaphragmatic postural and sphincter function are likely interrelated in this population. Copyright © 2015 Elsevier Ltd. All rights reserved.

The second leg home advantage: evidence from European football cup competitions.

PubMed

Page, Lionel; Page, Katie

2007-12-01

The home advantage is a widely acknowledged sporting phenomenon, especially in association football. Here, we examine the second leg home advantage, an effect that is discussed in the public domain but which has received very little scientific attention. The second leg home advantage effect occurs when on average teams are more likely to win a two-stage knock-out competition when they play at home in the second leg. That is, both teams have a home advantage but this advantage is significantly greater for the team that plays at home second. Examining data from three different European Cup football competitions spanning 51 years, we show that the second leg home advantage is a real phenomenon. The second leg home team has more than a 50% probability to qualify for the next round in the competition even after controlling for extra time and team ability as possible alternative explanations. The second leg home advantage appears, however, to have decreased significantly over the past decade. Possible reasons for its existence and subsequent decline are presented.

Hemodynamic effect and safety of intermittent sequential pneumatic compression leg sleeves in patients with congestive heart failure.

PubMed

Bickel, Amitai; Shturman, Alexander; Sergeiev, Michael; Ivry, Shimon; Eitan, Arieh; Atar, Shaul

2014-10-01

Pneumatic leg sleeves are widely used after prolonged operations for prevention of venous stasis. In healthy volunteers they increase cardiac function. We evaluated the hemodynamic effects and safety of intermittent sequential pneumatic compression (ISPC) leg sleeves in patients with chronic congestive heart failure (CHF). We studied 19 patients with systolic left ventricular dysfunction and CHF. ISPC leg sleeves, each with 10 air cells, were operated by a computerized compressor, exerting 2 cycles/min. Hemodynamic and echocardiographic parameters were measured before, during, and after ISPC activation. The baseline mean left ventricular ejection fraction was 29 ± 9.2%, median 32%, range 10%-40%. Cardiac output (from 4.26 to 4.83 L/min; P = .008) and stroke volume (from 56.1 to 63.5 mL; P = .029) increased significantly after ISPC activation, without a reciprocal increase in heart rate, and declined after sleeve deactivation. Systemic vascular resistance (SVR) decreased significantly (from 1,520 to 1,216 dyne-s/cm5; P = .0005), and remained lower than the baseline level throughout the study. There was no detrimental effect on diastolic function and no adverse clinical events, despite increased pulmonary venous return. ISPC leg sleeves in patients with chronic CHF do not exacerbate symptoms and transiently improve cardiac output through an increase in stroke volume and a reduction in SVR. Copyright © 2014 Elsevier Inc. All rights reserved.

Single-leg hop testing following fatiguing exercise: reliability and biomechanical analysis.

PubMed

Augustsson, J; Thomeé, R; Lindén, C; Folkesson, M; Tranberg, R; Karlsson, J

2006-04-01

knee flexion and generated powers for the knee and ankle joints during take-off, and less hip joint moments during landing under fatigued conditions. The large negative power values observed at the knee joint during the landing phase of the single-leg hop, during which the quadriceps muscle activates eccentrically, indicate that not only hop distance but also the ability to perform successful landings should be investigated when assessing dynamic knee function.

Profiling Isokinetic Strength by Leg Preference and Position in Rugby Union Athletes.

PubMed

Brown, Scott R; Brughelli, Matt; Bridgeman, Lee A

2016-05-01

Muscle imbalances aid in the identification of athletes at risk for lower-extremity injury. Little is known regarding the influence that leg preference or playing position may have on lower-extremity muscle strength and asymmetry. To investigate lower-extremity strength profiles in rugby union athletes and compare isokinetic knee- and hip-strength variables between legs and positions. Thirty male academy rugby union athletes, separated into forwards (n = 15) and backs (n = 15), participated in this cross-sectional analysis. Isokinetic dynamometry was used to evaluate peak torque, angle of peak torque, and strength ratios of the preferred and nonpreferred legs during seated knee extension/flexion and supine hip extension/flexion at 60°/s. Backs were older (ES = 1.6) but smaller in stature (ES = -0.47) and body mass (ES = -1.3) than the forwards. The nonpreferred leg was weaker than the preferred leg for forwards during extension (ES = -0.37) and flexion (ES = -0.21) actions and for backs during extension (ES = -0.28) actions. Backs were weaker at the knee than forwards in the preferred leg during extension (ES = -0.50) and flexion (ES = -0.66) actions. No differences were observed in strength ratios between legs or positions. Backs produced peak torque at longer muscle lengths in both legs at the knee (ES = -0.93 to -0.94) and hip (ES = -0.84 to -1.17) than the forwards. In this sample of male academy rugby union athletes, the preferred leg and forwards displayed superior strength compared with the nonpreferred leg and backs. These findings highlight the importance of individualized athletic assessments to detect crucial strength differences in male rugby union athletes.

Muscle activity during the active straight leg raise (ASLR), and the effects of a pelvic belt on the ASLR and on treadmill walking.

PubMed

Hu, Hai; Meijer, Onno G; van Dieën, Jaap H; Hodges, Paul W; Bruijn, Sjoerd M; Strijers, Rob L; Nanayakkara, Prabath W; van Royen, Barend J; Wu, Wenhua; Xia, Chun

2010-02-10

Women with pregnancy-related pelvic girdle pain (PPP), or athletes with groin pain, may have trouble with the active straight leg raise (ASLR), for which a pelvic belt can be beneficial. How the problems emerge, or how the belt works, remains insufficiently understood. We assessed muscle activity during ASLR, and how it changes with a pelvic belt. Healthy nulligravidae (N=17) performed the ASLR, and walked on a treadmill at increasing speeds, without and with a belt. Fine-wire electromyography (EMG) was used to record activity of the mm. psoas, iliacus and transversus abdominis, while other hip and trunk muscles were recorded with surface EMG. In ASLR, all muscles were active. In both tasks, transverse and oblique abdominal muscles were less active with the belt. In ASLR, there was more activity of the contralateral m. biceps femoris, and in treadmill walking of the m. gluteus maximus in conditions with a belt. For our interpretation, we take our starting point in the fact that hip flexors exert a forward rotating torque on the ilium. Apparently, the abdominal wall was active to prevent such forward rotation. If transverse and oblique abdominal muscles press the ilia against the sacrum (Snijders' "force closure"), the pelvis may move as one unit in the sagittal plane, and also contralateral hip extensor activity will stabilize the ipsilateral ilium. The fact that transverse and oblique abdominal muscles were less active in conditions with a pelvic belt suggests that the belt provides such "force closure", thus confirming Snijders' theory. Copyright 2009 Elsevier Ltd. All rights reserved.

Scaling of avian bipedal locomotion reveals independent effects of body mass and leg posture on gait.

PubMed

Daley, Monica A; Birn-Jeffery, Aleksandra

2018-05-22

Birds provide an interesting opportunity to study the relationships between body size, limb morphology and bipedal locomotor function. Birds are ecologically diverse and span a large range of body size and limb proportions, yet all use their hindlimbs for bipedal terrestrial locomotion, for at least some part of their life history. Here, we review the scaling of avian striding bipedal gaits to explore how body mass and leg morphology influence walking and running. We collate literature data from 21 species, spanning a 2500× range in body mass from painted quail to ostriches. Using dynamic similarity theory to interpret scaling trends, we find evidence for independent effects of body mass, leg length and leg posture on gait. We find no evidence for scaling of duty factor with body size, suggesting that vertical forces scale with dynamic similarity. However, at dynamically similar speeds, large birds use relatively shorter stride lengths and higher stride frequencies compared with small birds. We also find that birds with long legs for their mass, such as the white stork and red-legged seriema, use longer strides and lower swing frequencies, consistent with the influence of high limb inertia on gait. We discuss the observed scaling of avian bipedal gait in relation to mechanical demands for force, work and power relative to muscle actuator capacity, muscle activation costs related to leg cycling frequency, and considerations of stability and agility. Many opportunities remain for future work to investigate how morphology influences gait dynamics among birds specialized for different habitats and locomotor behaviors. © 2018. Published by The Company of Biologists Ltd.

Lower Leg Anterior and Lateral Intracompartmental Pressure Changes Before and After Classic Versus Skate Nordic Rollerskiing

PubMed Central

Woods, Katherine M.; Petron, David J.; Shultz, Barry B.; Hicks-Little, Charlie A.

2015-01-01

lower leg pain 11-point Numeric Rating Scale results indicate that increases in lower leg ICPs sustained during Nordic rollerskiing may increase discomfort during activity. Our results therefore suggest that Nordic rollerskiing contributes to increases in ICPs, which may lead to the development of CECS. PMID:26090709

Whole person-evoked fMRI activity patterns in human fusiform gyrus are accurately modeled by a linear combination of face- and body-evoked activity patterns

PubMed Central

Kaiser, Daniel; Strnad, Lukas; Seidl, Katharina N.; Kastner, Sabine

2013-01-01

Visual cues from the face and the body provide information about another's identity, emotional state, and intentions. Previous neuroimaging studies that investigated neural responses to (bodiless) faces and (headless) bodies have reported overlapping face- and body-selective brain regions in right fusiform gyrus (FG). In daily life, however, faces and bodies are typically perceived together and are effortlessly integrated into the percept of a whole person, raising the possibility that neural responses to whole persons are qualitatively different than responses to isolated faces and bodies. The present study used fMRI to examine how FG activity in response to a whole person relates to activity in response to the same face and body but presented in isolation. Using multivoxel pattern analysis, we modeled person-evoked response patterns in right FG through a linear combination of face- and body-evoked response patterns. We found that these synthetic patterns were able to accurately approximate the response patterns to whole persons, with face and body patterns each adding unique information to the response patterns evoked by whole person stimuli. These results suggest that whole person responses in FG primarily arise from the coactivation of independent face- and body-selective neural populations. PMID:24108794

Carotid baroreflex control of leg vasculature in exercising and non-exercising skeletal muscle in humans

PubMed Central

Melvin Keller, David; Fadel, Paul J; Ogoh, Shigehiko; Matthew Brothers, Robert; Hawkins, Megan; Olivencia-Yurvati, Al; Raven, Peter B

2004-01-01

Carotid baroreflex (CBR) function was examined in five men and three women (25 ± 1 years) using the variable-pressure neck collar technique at rest and during dynamic, one-legged knee extension exercise at 7 W and 25 W. The CBR exhibited control of leg vascular conductance (LVC) at rest and during exercise in both an exercising leg (EL) and a non-exercising leg (NEL) across a wide range of pressures from +40 Torr neck pressure (NP) to −80 Torr neck suction (NS). Specifically, increases in LVC (% change) in response to NS were no different across −20 to −80 Torr in either EL or NEL compared to rest, P > 0.05. However, CBR-mediated decreases in percentage LVC in response to NP were attenuated in EL at both 7 W (16 ± 1%) and 25 W (12 ± 1%) compared to rest (40 ± 3%; P < 0.05) as well as compared to responses in the NEL (36 ± 6% at 7 W and 36 ± 7% at 25 W; P < 0.05). This decrease in vascular responsiveness in EL was associated with a reduction in the gain of the percentage muscle sympathetic nerve activity (%MSNA)–%LVC relationship compared to rest (P < 0.05). Collectively, these data indicate that, despite a clear attenuation of the vascular response to MSNA in the exercising leg, CBR-mediated changes in mean arterial pressure were no different between rest and exercise. PMID:15388778

[Measurement of external pressure of peroneal nerve tract coming in contact with lithotomy leg holders using pressure distribution measurement system BIG-MAT®].

PubMed

Mizuno, Ju; Namba, Chikara; Takahashi, Toru

2014-10-01

We investigated external pressure on peroneal nerve tract coming in contact with two kinds of leg holders using pressure distribution measurement system BIG- MAT® (Nitta Corp., Osaka) in the lithotomy position Peak contact (active) pressure at the left fibular head region coming in contact with knee-crutch-type leg holder M® (Takara Belmont Corp., Osaka), which supports the left popliteal fossa, was 78.0 ± 26.4 mmHg. On the other hand, peak contact pressure at the left lateral lower leg region coming in contact with boot-support-type leg holder Bel Flex® (Takara Belmont Corp., Osaka), which supports the left lower leg and foot was 26.3±7.9 mmHg. These results suggest that use of knee-crutch-type leg holder is more likely to induce common peroneal nerve palsy at the fibular head region, but use of boot-support-type leg holder dose not easily induce superficial peroneal nerve palsy at the lateral lower leg region, because capillary blood pressure is known to be 32 mmHg. Safer holders for positioning will be developed to prevent nerve palsy based on the analysis of chronological change in external pressure using BIG-MAT® system during anesthesia.

Rotational joint assembly for the prosthetic leg

NASA Technical Reports Server (NTRS)

Owens, L. J.; Jones, W. C. (Inventor)

1977-01-01

A rotational joint assembly for a prosthetic leg has been devised, which enables an artificial foot to rotate slightly when a person is walking, running or turning. The prosthetic leg includes upper and lower tubular members with the rotational joint assembly interposed between them. The assembly includes a restrainer mechanism which consists of a pivotably mounted paddle element. This device applies limiting force to control the rotation of the foot and also restores torque to return the foot back to its initial position.

Extensive Reading in the EFL Classroom: Benefits of a Face-to-Face Collaboration Activity

ERIC Educational Resources Information Center

Kirchhoff, Cheryl

2015-01-01

Extensive reading is an approach to language education that has shown great promise for foreign language learners to acquire language; however, implementation reveals difficulty in maintaining student motivation to read over long periods of time. This study investigates students' experience of face-to-face talk about books in an extensive reading…

CT angiography - arms and legs

MedlinePlus

... this page: //medlineplus.gov/ency/article/007675.htm CT angiography - arms and legs To use the sharing features on this page, please enable JavaScript. CT angiography combines a CT scan with the injection ...

Haemoglobin saturation during incremental arm and leg exercise.

PubMed Central

Powers, S. K.; Dodd, S.; Woodyard, J.; Beadle, R. E.; Church, G.

1984-01-01

There are few reports concerning the alterations in the percent of haemoglobin saturated with oxygen (%SO2) during non-steady state incremental exercise. Further, no data exist to describe the %SO2 changes during arm exercise. Therefore, the purpose of this study was made to assess the dynamic changes in %SO2 during incremental arm and leg work. Nine trained subjects (7 males and 2 females) performed incremental arm and leg exercise to exhaustion on an arm crank ergometer and a cycle ergometer, respectively. Ventilation and gas exchange measurements were obtained minute by minute via open circuit spirometry and changes in %SO2 were recorded via an ear oximeter. No significant difference (p greater than 0.05) existed between arm and leg work in end-tidal oxygen (PETO2), end-tidal carbon dioxide (PETCO2), or %SO2 when compared as a function of percent VO2 max. These results provide evidence that arterial O2 desaturation occurs in a similar fashion in both incremental arm and leg work with the greatest changes in %SO2 occurring at work rates greater than 70% VO2 max. PMID:6435715

Measurement and simulation of thermoelectric efficiency for single leg

NASA Astrophysics Data System (ADS)

Hu, Xiaokai; Yamamoto, Atsushi; Ohta, Michihiro; Nishiate, Hirotaka

2015-04-01

Thermoelectric efficiency measurements were carried out on n-type bismuth telluride legs with the hot-side temperature at 100 and 150 °C. The electric power and heat flow were measured individually. Water coolant was utilized to maintain the cold-side temperature and to measure heat flow out of the cold side. Leg length and vacuum pressure were studied in terms of temperature difference across the leg, open-circuit voltage, internal resistance, and heat flow. Finite-element simulation on thermoelectric generation was performed in COMSOL Multiphysics, by inputting two-side temperatures and thermoelectric material properties. The open-circuit voltage and resistance were in good agreement between the measurement and simulation. Much larger heat flows were found in measurements, since they were comprised of conductive, convective, and radiative contributions. Parasitic heat flow was measured in the absence of bismuth telluride leg, and the conductive heat flow was then available. Finally, the maximum thermoelectric efficiency was derived in accordance with the electric power and the conductive heat flow.

Many faces of expertise: fusiform face area in chess experts and novices.

PubMed

Bilalić, Merim; Langner, Robert; Ulrich, Rolf; Grodd, Wolfgang

2011-07-13

The fusiform face area (FFA) is involved in face perception to such an extent that some claim it is a brain module for faces exclusively. The other possibility is that FFA is modulated by experience in individuation in any visual domain, not only faces. Here we test this latter FFA expertise hypothesis using the game of chess as a domain of investigation. We exploited the characteristic of chess, which features multiple objects forming meaningful spatial relations. In three experiments, we show that FFA activity is related to stimulus properties and not to chess skill directly. In all chess and non-chess tasks, experts' FFA was more activated than that of novices' only when they dealt with naturalistic full-board chess positions. When common spatial relationships formed by chess objects in chess positions were randomly disturbed, FFA was again differentially active only in experts, regardless of the actual task. Our experiments show that FFA contributes to the holistic processing of domain-specific multipart stimuli in chess experts. This suggests that FFA may not only mediate human expertise in face recognition but, supporting the expertise hypothesis, may mediate the automatic holistic processing of any highly familiar multipart visual input.

Abnormal brain activation during threatening face processing in schizophrenia: A meta-analysis of functional neuroimaging studies.

PubMed

Dong, Debo; Wang, Yulin; Jia, Xiaoyan; Li, Yingjia; Chang, Xuebin; Vandekerckhove, Marie; Luo, Cheng; Yao, Dezhong

2017-11-15

Impairment of face perception in schizophrenia is a core aspect of social cognitive dysfunction. This impairment is particularly marked in threatening face processing. Identifying reliable neural correlates of the impairment of threatening face processing is crucial for targeting more effective treatments. However, neuroimaging studies have not yet obtained robust conclusions. Through comprehensive literature search, twenty-one whole brain datasets were included in this meta-analysis. Using seed-based d-Mapping, in this voxel-based meta-analysis, we aimed to: 1) establish the most consistent brain dysfunctions related to threating face processing in schizophrenia; 2) address task-type heterogeneity in this impairment; 3) explore the effect of potential demographic or clinical moderator variables on this impairment. Main meta-analysis indicated that patients with chronic schizophrenia demonstrated attenuated activations in limbic emotional system along with compensatory over-activation in medial prefrontal cortex (MPFC) during threatening faces processing. Sub-task analyses revealed under-activations in right amygdala and left fusiform gyrus in both implicit and explicit tasks. The remaining clusters were found to be differently involved in different types of tasks. Moreover, meta-regression analyses showed brain abnormalities in schizophrenia were partly modulated by age, gender, medication and severity of symptoms. Our results highlighted breakdowns in limbic-MPFC circuit in schizophrenia, suggesting general inability to coordinate and contextualize salient threat stimuli. These findings provide potential targets for neurotherapeutic and pharmacological interventions for schizophrenia. Copyright © 2017 Elsevier B.V. All rights reserved.

Method for six-legged robot stepping on obstacles by indirect force estimation

NASA Astrophysics Data System (ADS)

Xu, Yilin; Gao, Feng; Pan, Yang; Chai, Xun

2016-07-01

Adaptive gaits for legged robots often requires force sensors installed on foot-tips, however impact, temperature or humidity can affect or even damage those sensors. Efforts have been made to realize indirect force estimation on the legged robots using leg structures based on planar mechanisms. Robot Octopus III is a six-legged robot using spatial parallel mechanism(UP-2UPS) legs. This paper proposed a novel method to realize indirect force estimation on walking robot based on a spatial parallel mechanism. The direct kinematics model and the inverse kinematics model are established. The force Jacobian matrix is derived based on the kinematics model. Thus, the indirect force estimation model is established. Then, the relation between the output torques of the three motors installed on one leg to the external force exerted on the foot tip is described. Furthermore, an adaptive tripod static gait is designed. The robot alters its leg trajectory to step on obstacles by using the proposed adaptive gait. Both the indirect force estimation model and the adaptive gait are implemented and optimized in a real time control system. An experiment is carried out to validate the indirect force estimation model. The adaptive gait is tested in another experiment. Experiment results show that the robot can successfully step on a 0.2 m-high obstacle. This paper proposes a novel method to overcome obstacles for the six-legged robot using spatial parallel mechanism legs and to avoid installing the electric force sensors in harsh environment of the robot's foot tips.

Early life stress and trauma and enhanced limbic activation to emotionally valenced faces in depressed and healthy children.

PubMed

Suzuki, Hideo; Luby, Joan L; Botteron, Kelly N; Dietrich, Rachel; McAvoy, Mark P; Barch, Deanna M

2014-07-01

Previous studies have examined the relationships between structural brain characteristics and early life stress in adults. However, there is limited evidence for functional brain variation associated with early life stress in children. We hypothesized that early life stress and trauma would be associated with increased functional brain activation response to negative emotional faces in children with and without a history of depression. Psychiatric diagnosis and life events in children (starting at age 3-5 years) were assessed in a longitudinal study. A follow-up magnetic resonance imaging (MRI) study acquired data (N = 115 at ages 7-12, 51% girls) on functional brain response to fearful, sad, and happy faces relative to neutral faces. We used a region-of-interest mask within cortico-limbic areas and conducted regression analyses and repeated-measures analysis of covariance. Greater activation responses to fearful, sad, and happy faces in the amygdala and its neighboring regions were found in children with greater life stress. Moreover, an association between life stress and left hippocampal and globus pallidus activity depended on children's diagnostic status. Finally, all children with greater life trauma showed greater bilateral amygdala and cingulate activity specific to sad faces but not the other emotional faces, although right amygdala activity was moderated by psychiatric status. These findings suggest that limbic hyperactivity may be a biomarker of early life stress and trauma in children and may have implications in the risk trajectory for depression and other stress-related disorders. However, this pattern varied based on emotion type and history of psychopathology. Copyright © 2014 American Academy of Child and Adolescent Psychiatry. Published by Elsevier Inc. All rights reserved.

Dissecting contributions of prefrontal cortex and fusiform face area to face working memory.

PubMed

Druzgal, T Jason; D'Esposito, Mark

2003-08-15

Interactions between prefrontal cortex (PFC) and stimulus-specific visual cortical association areas are hypothesized to mediate visual working memory in behaving monkeys. To clarify the roles for homologous regions in humans, event-related fMRI was used to assess neural activity in PFC and fusiform face area (FFA) of subjects performing a delay-recognition task for faces. In both PFC and FFA, activity increased parametrically with memory load during encoding and maintenance of face stimuli, despite quantitative differences in the magnitude of activation. Moreover, timing differences in PFC and FFA activation during memory encoding and retrieval implied a context dependence in the flow of neural information. These results support existing neurophysiological models of visual working memory developed in the nonhuman primate.

Detection of Periodic Leg Movements by Machine Learning Methods Using Polysomnographic Parameters Other Than Leg Electromyography

PubMed Central

Umut, İlhan; Çentik, Güven

2016-01-01

The number of channels used for polysomnographic recording frequently causes difficulties for patients because of the many cables connected. Also, it increases the risk of having troubles during recording process and increases the storage volume. In this study, it is intended to detect periodic leg movement (PLM) in sleep with the use of the channels except leg electromyography (EMG) by analysing polysomnography (PSG) data with digital signal processing (DSP) and machine learning methods. PSG records of 153 patients of different ages and genders with PLM disorder diagnosis were examined retrospectively. A novel software was developed for the analysis of PSG records. The software utilizes the machine learning algorithms, statistical methods, and DSP methods. In order to classify PLM, popular machine learning methods (multilayer perceptron, K-nearest neighbour, and random forests) and logistic regression were used. Comparison of classified results showed that while K-nearest neighbour classification algorithm had higher average classification rate (91.87%) and lower average classification error value (RMSE = 0.2850), multilayer perceptron algorithm had the lowest average classification rate (83.29%) and the highest average classification error value (RMSE = 0.3705). Results showed that PLM can be classified with high accuracy (91.87%) without leg EMG record being present. PMID:27213008

Detection of Periodic Leg Movements by Machine Learning Methods Using Polysomnographic Parameters Other Than Leg Electromyography.

PubMed

Umut, İlhan; Çentik, Güven

2016-01-01

The number of channels used for polysomnographic recording frequently causes difficulties for patients because of the many cables connected. Also, it increases the risk of having troubles during recording process and increases the storage volume. In this study, it is intended to detect periodic leg movement (PLM) in sleep with the use of the channels except leg electromyography (EMG) by analysing polysomnography (PSG) data with digital signal processing (DSP) and machine learning methods. PSG records of 153 patients of different ages and genders with PLM disorder diagnosis were examined retrospectively. A novel software was developed for the analysis of PSG records. The software utilizes the machine learning algorithms, statistical methods, and DSP methods. In order to classify PLM, popular machine learning methods (multilayer perceptron, K-nearest neighbour, and random forests) and logistic regression were used. Comparison of classified results showed that while K-nearest neighbour classification algorithm had higher average classification rate (91.87%) and lower average classification error value (RMSE = 0.2850), multilayer perceptron algorithm had the lowest average classification rate (83.29%) and the highest average classification error value (RMSE = 0.3705). Results showed that PLM can be classified with high accuracy (91.87%) without leg EMG record being present.

Loss of legs: is it or not a handicap for an orb-weaving spider?

NASA Astrophysics Data System (ADS)

Pasquet, Alain; Anotaux, Mylène; Leborgne, Raymond

2011-07-01

Leg loss is a common phenomenon in spiders, and according to the species 5% to 40% of the adults can present at least one missing leg. There is no possibility of regeneration after adult moult and the animal must manage with its missing appendages until its death. With the loss of one or more legs, female orb-weaving spiders can be penalized twice: firstly, because the legs are necessary for web construction and secondly, the legs are essential for the control of the prey after its interception by the web. During development, spiders may be also penalized because regeneration has energetic costs that take away resources for survival, growth and reproduction. All these consequences should influence negatively the development of the spider and thus its fitness. We investigated the impact of leg loss in the orb-weaving spider, Zygiella x-notata by studying its frequency in a natural population and web building and prey capture behaviours in laboratory. In field populations, 9.5% to 13%, of the adult females presented the loss of one or more legs; the majority of individuals had lost only one leg (in 48% of cases, a first one). Leg loss seems to affect all the adult spiders, as there is no difference of mass between intact spiders and those with missing leg. Data obtained with laboratory-reared spiders, showed that the loss of legs due to the moult is rare (less than 1%). Considering changes in web design, spiders with missing legs decreased their silk investment, increased the distance between spiral turns but did not change the capture surface of the web. Under our laboratory experimental conditions, spiders with one or two lost legs did not present any difference in prey capture efficiency. In laboratory conditions, spiders with lost leg(s) did not show any difference in egg sac production or in longevity (adult lifespan) compared to intact spiders.

Real-Time and High-Resolution 3D Face Measurement via a Smart Active Optical Sensor.

PubMed

You, Yong; Shen, Yang; Zhang, Guocai; Xing, Xiuwen

2017-03-31

The 3D measuring range and accuracy in traditional active optical sensing, such as Fourier transform profilometry, are influenced by the zero frequency of the captured patterns. The phase-shifting technique is commonly applied to remove the zero component. However, this phase-shifting method must capture several fringe patterns with phase difference, thereby influencing the real-time performance. This study introduces a smart active optical sensor, in which a composite pattern is utilized. The composite pattern efficiently combines several phase-shifting fringes and carrier frequencies. The method can remove zero frequency by using only one pattern. Model face reconstruction and human face measurement were employed to study the validity and feasibility of this method. Results show no distinct decrease in the precision of the novel method unlike the traditional phase-shifting method. The texture mapping technique was utilized to reconstruct a nature-appearance 3D digital face.

Real-Time and High-Resolution 3D Face Measurement via a Smart Active Optical Sensor

PubMed Central

You, Yong; Shen, Yang; Zhang, Guocai; Xing, Xiuwen

2017-01-01

The 3D measuring range and accuracy in traditional active optical sensing, such as Fourier transform profilometry, are influenced by the zero frequency of the captured patterns. The phase-shifting technique is commonly applied to remove the zero component. However, this phase-shifting method must capture several fringe patterns with phase difference, thereby influencing the real-time performance. This study introduces a smart active optical sensor, in which a composite pattern is utilized. The composite pattern efficiently combines several phase-shifting fringes and carrier frequencies. The method can remove zero frequency by using only one pattern. Model face reconstruction and human face measurement were employed to study the validity and feasibility of this method. Results show no distinct decrease in the precision of the novel method unlike the traditional phase-shifting method. The texture mapping technique was utilized to reconstruct a nature-appearance 3D digital face. PMID:28362349

Leg orientation as a clinical sign for pusher syndrome

PubMed Central

Johannsen, Leif; Broetz, Doris; Karnath, Hans-Otto

2006-01-01

Background Effective control of (upright) body posture requires a proper representation of body orientation. Stroke patients with pusher syndrome were shown to suffer from severely disturbed perception of own body orientation. They experience their body as oriented 'upright' when actually tilted by nearly 20° to the ipsilesional side. Thus, it can be expected that postural control mechanisms are impaired accordingly in these patients. Our aim was to investigate pusher patients' spontaneous postural responses of the non-paretic leg and of the head during passive body tilt. Methods A sideways tilting motion was applied to the trunk of the subject in the roll plane. Stroke patients with pusher syndrome were compared to stroke patients not showing pushing behaviour, patients with acute unilateral vestibular loss, and non brain damaged subjects. Results Compared to all groups without pushing behaviour, the non-paretic leg of the pusher patients showed a constant ipsiversive tilt across the whole tilt range for an amount which was observed in the non-pusher subjects when they were tilted for about 15° into the ipsiversive direction. Conclusion The observation that patients with acute unilateral vestibular loss showed no alterations of leg posture indicates that disturbed vestibular afferences alone are not responsible for the disordered leg responses seen in pusher patients. Our results may suggest that in pusher patients a representation of body orientation is disturbed that drives both conscious perception of body orientation and spontaneous postural adjustment of the non-paretic leg in the roll plane. The investigation of the pusher patients' leg-to-trunk orientation thus could serve as an additional bedside tool to detect pusher syndrome in acute stroke patients. PMID:16928280

Genetic analysis of feet and leg conformation traits in Nelore cattle.

PubMed

Vargas, G; Neves, H H R; Cardoso, V; Munari, D P; Carvalheiro, R

2017-06-01

Feet and leg conformation scores are important traits in beef cattle because they encompass a wide range of locomotion disorders that can lead to productive and reproductive losses. Thus, the study of feet and legs in beef cattle is essential for evaluating possible responses to selection focusing on minimizing economic losses caused by the occurrence of feet and leg problems. The aim of this study was to estimate variance components for feet and leg conformation traits in Nelore cattle. The data set contained records of approximately 300,000 animals that were born between 2000 and 2013. These animals belonged to the commercial beef cattle breeding program of the CRV Lagoa (). Feet and legs were evaluated by assigning visual scores at 2 different time points: feet and leg evaluated as a binary trait (FL1), measured at yearling (about 550 d of age) to identify whether (or not) an animal has feet and leg defects, and feet and leg score (FL2), ranging from 1 (less desirable) to 5 (more desirable) was assigned to the top 20% of animals according to the selection index adopted by the beef cattle breeding program, which was measured 2 to 5 mo after the yearling evaluation. The FL1 and FL2 traits were analyzed together with yearling weight (YW). The (co)variance components and breeding values were estimated by Bayesian inference using 2-trait animal models. The posterior means (standard errors) of the heritabilities for FL1, FL2, and YW were 0.18 (0.04), 0.39 (0.07), and 0.47 (0.01), respectively. The results indicate that the incidence of feet and leg problems in this population might be reduced by selection. The genetic correlation between FL1 and FL2 (-0.47) was moderate and negative as expected because the classification score that holds up each trait has opposite numerical values. The genetic trends estimated for FL1 and FL2 (-0.042 and 0.021 genetic standard deviations per year, respectively) were favorable and they indicate that the independent culling strategy for

Mechanical Impedance of the Non-loaded Lower Leg with Relaxed Muscles in the Transverse Plane

PubMed Central

Ficanha, Evandro Maicon; Ribeiro, Guilherme Aramizo; Rastgaar, Mohammad

2015-01-01

This paper describes the protocols and results of the experiments for the estimation of the mechanical impedance of the humans’ lower leg in the External–Internal direction in the transverse plane under non-load bearing condition and with relaxed muscles. The objectives of the estimation of the lower leg’s mechanical impedance are to facilitate the design of passive and active prostheses with mechanical characteristics similar to the humans’ lower leg, and to define a reference that can be compared to the values from the patients suffering from spasticity. The experiments were performed with 10 unimpaired male subjects using a lower extremity rehabilitation robot (Anklebot, Interactive Motion Technologies, Inc.) capable of applying torque perturbations to the foot. The subjects were in a seated position, and the Anklebot recorded the applied torques and the resulting angular movement of the lower leg. In this configuration, the recorded dynamics are due mainly to the rotations of the ankle’s talocrural and the subtalar joints, and any contribution of the tibiofibular joints and knee joint. The dynamic mechanical impedance of the lower leg was estimated in the frequency domain with an average coherence of 0.92 within the frequency range of 0–30 Hz, showing a linear correlation between the displacement and the torques within this frequency range under the conditions of the experiment. The mean magnitude of the stiffness of the lower leg (the impedance magnitude averaged in the range of 0–1 Hz) was determined as 4.9 ± 0.74 Nm/rad. The direct estimation of the quasi-static stiffness of the lower leg results in the mean value of 5.8 ± 0.81 Nm/rad. An analysis of variance shows that the estimated values for the stiffness from the two experiments are not statistically different. PMID:26697424

Intensity of leg and arm training after primary middle-cerebral-artery stroke: a randomised trial.

PubMed

Kwakkel, G; Wagenaar, R C; Twisk, J W; Lankhorst, G J; Koetsier, J C

1999-07-17

We investigated the effects of different intensities of arm and leg rehabilitation training on the functional recovery of activities of daily living (ADL), walking ability, and dexterity of the paretic arm, in a single-blind randomised controlled trial. Within 14 days after stroke onset, 101 severely disabled patients with a primary middle-cerebral-artery stroke were randomly assigned to: a rehabilitation programme with emphasis on arm training; a rehabilitation programme with emphasis on leg training; or a control programme in which the arm and leg were immobilised with an inflatable pressure splint. Each treatment regimen was applied for 30 min, 5 days a week during the first 20 weeks after stroke. In addition, all patients underwent a basic rehabilitation programme. The main outcome measures were ability in ADL (Barthel index), walking ability (functional ambulation categories), and dexterity of the paretic arm (Action Research arm test) at 6, 12, 20, and 26 weeks. Analyses were by intention to treat. At week 20, the leg-training group (n=31) had higher scores than the control group (n=37) for ADL ability (median 19 [IQR 16-20] vs 16 [10-19], p<0.05), walking ability (4 [3-5] vs 3 [1-4], p<0.05), and dexterity (2 [0-56] vs 0 [0-2], p<0.01). The arm-training group (n=33) differed significantly from the control group only in dexterity (9 [0-39] vs 0 [0-2], p<0.01). There were no significant differences in these endpoints at 20 weeks between the arm-training and leg-training groups. Greater intensity of leg rehabilitation improves functional recovery and health-related functional status, whereas greater intensity of arm rehabilitation results in small improvements in dexterity, providing further evidence that exercise therapy primarily induces treatment effects on the abilities at which training is specifically aimed.

[Fractures of the lower leg in professional skiers].

PubMed

Mückley, T; Kruis, C; Schütz, T; Brucker, P; Bühren, V

2004-03-01

Fractures of the lower leg due to skiing accidents remain an important concern. Few studies have focussed on the special demands of professional athletes who sustain these injuries. We present our experience with three cases of lower leg fractures in competitive professional downhill skiers and discuss management and treatment concepts. We performed limited reamed compression nailing in all the patients presented because it offers the advantages of high mechanical stability and optimized fragment apposition. Plate osteosynthesis of the fibula is not required in most typical fractures. All patients resumed ski training. Two of them returned to World Cup. Only one achieved her pre-injury World Cup level of performance and success. In conclusion, a successful return for professional skiers with lower leg fractures is feasible using an optimized treatment strategy.

Experiments in balance with a 2D one-legged hopping machine

NASA Astrophysics Data System (ADS)

Raibert, M. H.; Brown, H. B., Jr.

1984-03-01

The ability to balance is important to the mobility obtained by legged creatures found in nature, and may someday lead to versatile legged vehicles. In order to study the role of balance in legged locomotion and to develop appropriate control strategies, a 2D hopping machine was constructed for experimentation. The machine has one leg on which it hops and runs, making balance a prime consideration. Control of the machine's locomotion was decomposed into three separate parts: a vertical height control part, a horizontal velocity part, and an angular attitude control part. Experiments showed that the three part control scheme, while very simple to implement, was powerful enough to permit the machine to hop in place, to run at a desired rate, to translate from place to place, and to leap over obstacles. Results from modeling and computer simulation of a similar one-legged device are described by Raibert (1983).

Neuromuscular Activation During Short-Track Speed Skating in Young Athletes.

PubMed

Felser, Sabine; Behrens, Martin; Fischer, Susanne; Baeumler, Mario; Salomon, Ralf; Bruhn, Sven

2016-10-01

To investigate differences in muscle activation of both legs between the straight and the curve and changes in muscle activity during a 1000-m time trial (TT) and their relationship to the change in skating velocity in 9 young short-track speed skaters. The authors recorded skating times and EMG data from different leg muscles during maximum-effort skating trials on the straight and in the curve, as well as during a 1000-m TT. Muscle activation differs between the straight and the curves and between legs; ie, average activities of selected muscles of the right leg were significantly higher during skating through the curves than in the straights. This could not be observed for the left leg. The reduction in speed during the 1000-m TT highly correlates with the decrease in the muscle activity of both the tibialis anterior and the rectus femoris of the right leg. Muscle recruitment is different in relation to lap section (straight vs curve) and leg (right vs left leg). The decreased muscle activity of the tibialis anterior and rectus femoris of the right leg showed the highest relationships with the reduction in skating speed during the 1000-m TT.

Multi-Axis Prosthetic Knee Resembles Alpine Skiing Movements of an Intact Leg

PubMed Central

Demšar, Ivan; Duhovnik, Jože; Lešnik, Blaž; Supej, Matej

2015-01-01

The purpose of the study was to analyse the flexion angles of the ski boot, ankle and knee joints of an above-knee prosthesis and to compare them with an intact leg and a control group of skiers. One subject with an above-knee amputation of the right leg and eight healthy subjects simulated the movement of a skiing turn by performing two-leg squats in laboratory conditions. By adding additional loads in proportion to body weight (BW; +1/3 BW, +2/3 BW, +3/3 BW), various skiing regimes were simulated. Change of Flexion Angle (CoFA) and Range of Motion (RoM) in the ski boot, ankle and knee joints were calculated and compared. An average RoM in the skiing boot on the side of prosthesis (4.4 ± 1.1°) was significantly lower compared to an intact leg (5.9 ± 1.8°) and the control group (6.5 ± 2.3°). In the ankle joint, the average RoM was determined to be 13.2±2.9° in the prosthesis, 12.7 ± 2.8° in an intact leg and 14.8±3.6 in the control group. However, the RoM of the knee joint in the prosthesis (42.2 ± 4.2°) was significantly larger than that of the intact leg (34.7 ± 4.4°). The average RoM of the knee joint in the control group was 47.8 ± 5.4°. The influences of additional loads on the kinematics of the lower extremities were different on the side of the prosthesis and on the intact leg. In contrast, additional loads did not produce any significant differences in the control group. Although different CoFAs in the ski boot, ankle and knee joints were used, an above-knee prosthesis with a built-in multi-axis prosthetic knee enables comparable leg kinematics in simulated alpine skiing. Key points The RoM in the ski boot on the side of the prosthetic leg was smaller than the RoM of the intact leg and the control group of healthy subjects. The RoM in the ankle joint of prosthetic leg was comparable to that of the intact leg and the control group of healthy subjects. The RoM in the prosthetic knee joint was greater than the RoM in the knee joint of the

Parental smoking during pregnancy shortens offspring's legs.

PubMed

Żądzińska, E; Kozieł, S; Borowska-Strugińska, B; Rosset, I; Sitek, A; Lorkiewicz, W

2016-12-01

One of the most severe detrimental environmental factors acting during pregnancy is foetal smoke exposure. The aim of this study was to assess the effect of maternal, paternal and parental smoking during pregnancy on relative leg length in 7- to 10-year-old children. The research conducted in the years 2001-2002 included 978 term-born children, 348 boys and 630 girls, at the age of 7-10 years. Information concerning the birth weight of a child was obtained from the health records of the women. Information about the mother's and the father's smoking habits during pregnancy and about the mothers' education level was obtained from a questionnaire. The influence of parental smoking on relative leg length, controlled for age, sex, birth weight and the mother's education, as a proxy measure of socioeconomic status, and controlled for an interaction between sex and birth weight, was assessed by an analysis of covariance, where relative leg length was the dependent variable, smoking and sex were the independent variables, and birth weight as well as the mother's education were the covariates. Three separate analyses were run for the three models of smoking habits during pregnancy: the mother's smoking, the father's smoking and both parents' smoking. Only both parents' smoking showed a significant effect on relative leg length of offspring. It is probable that foetal hypoxia caused by carbon monoxide contained in smoke decelerated the growth of the long bones of foetuses. Copyright © 2016 Elsevier GmbH. All rights reserved.

Surgical treatment of chronic exertional compartment syndrome of the leg: failure rates and postoperative disability in an active patient population.

PubMed

Waterman, Brian R; Laughlin, Matthew; Kilcoyne, Kelly; Cameron, Kenneth L; Owens, Brett D

2013-04-03

Chronic exertional compartment syndrome of the leg is a frequent source of lower-extremity pain in military personnel, competitive athletes, and runners. We are not aware of any previous study in which the authors rigorously evaluated the rates of return to full activity, persistent disability, and surgical revision after operative management of chronic exertional compartment syndrome of the leg in a large, physically active population. Individuals who had undergone surgical fasciotomy of the anterior, lateral, and/or posterior compartments (current procedural terminology [CPT] codes 27600, 27601, and 27602) for nontraumatic compartment syndrome of the lower extremity (International Classification of Diseases, Ninth Revision [ICD-9] code 729.72) between 2003 and 2010 were identified from the Military Health System Management Analysis and Reporting Tool (M2). Demographic variables including age, sex, and rank were extracted, and rates of postoperative complications, activity limitations, and revision surgery or medical discharge were obtained from the electronic medical record and U.S. Army Physical Disability Agency database. A total of 611 patients underwent 754 surgical procedures. The average patient age was 28.0 years, and 91.8% of the patients were male. Of the surgical procedures, 77.4% involved only anterior and lateral compartment releases; 19.4% addressed the anterior, lateral, and posterior compartments; and 2.2% addressed the posterior compartments alone. Symptom recurrence was reported by 44.7% of the patients, and 27.7% were unable to return to full activity. Surgical complications were documented for 15.7% of the patients, 5.9% underwent surgical revision, and 17.3% were referred for medical discharge because of chronic exertional compartment syndrome. Univariate analysis of prognostic factors revealed that surgical failure was associated with bilateral involvement (odds ratio [OR], 1.64), perioperative complications (OR, 2.12), activity limitations

Design of a Single Motor Based Leg Structure with the Consideration of Inherent Mechanical Stability

NASA Astrophysics Data System (ADS)

Taha Manzoor, Muhammad; Sohail, Umer; Noor-e-Mustafa; Nizami, Muhammad Hamza Asif; Ayaz, Yasar

2017-07-01

The fundamental aspect of designing a legged robot is constructing a leg design that is robust and presents a simple control problem. In this paper, we have successfully designed a robotic leg based on a unique four bar mechanism with only one motor per leg. The leg design parameters used in our platform are extracted from design principles used in biological systems, multiple iterations and previous research findings. These principles guide a robotic leg to have minimal mechanical passive impedance, low leg mass and inertia, a suitable foot trajectory utilizing a practical balance between leg kinematics and robot usage, and the resultant inherent mechanical stability. The designed platform also exhibits the key feature of self-locking. Theoretical tools and software iterations were used to derive these practical features and yield an intuitive sense of the required leg design parameters.

Increase in Leg Stiffness Reduces Joint Work During Backpack Carriage Running at Slow Velocities.