Effects of wearing an ankle brace on ground reaction forces during jumps in basketball game simulation / Efectos del uso de órtesis de tobillo sobre las fuerzas de reacción del suelo durante los saltos en simulación de juego de baloncesto / Efeitos do uso de órtese de tornozelo sobre as forças de reação do solo durante saltos em simulação do jogo de basquetebol

ABSTRACT Introduction: The use of ankle braces reduces the risk of ankle injuries in basketball players. However, the mechanisms of injury protection provided by the ankle braces in the basketball game are still unknown. Objectives: To analyze the effects of wearing a lace-up ankle brace, and to conduct an exercise protocol that simulated the intensity of the basketball game on ground reaction force (GRF) during basketball-specific vertical jumps. Methods: Eleven male younger basketball players aged under 18 completed 48 vertical jumps, with and without ankle braces, during an exercise protocol composed of four 10-minute periods, simulating the activity profile and intensity of the basketball game as well as the typical intervals between periods. Mediolateral (variables: the greatest medial and lateral peaks) and vertical (variables: vertical peak, impulse peak, impulse at 50 ms of landing, loading rate and jump height) GRF were measured during takeoff and landing for all the jumps performed in the exercise protocol. Results: The use of the ankle brace reduced mediolateral GRF in all periods of the exercise protocol during takeoff and landing ( P < 0.05), without affecting the vertical GRF ( P > 0.05). Mediolateral and vertical GRF (takeoff mediolateral vertical peaks, landing mediolateral peaks, landing impulse peak, takeoff and landing loading rate) increased significantly during four subsequent 10-minute periods ( P < 0.05). However, for mediolateral GRF, the increase overtime was higher without braces. Conclusions: The use of the ankle brace reduced the mediolateral GRF on the lower limb, while there was a progressive increase in the external load applied to the body during the vertical jumps in the subsequent periods of the exercise protocol performed at the same intensity of the basketball game. Level of evidence I; Randomized clinical trial .

RESUMEN Introducción: El uso de órtesis de tobillo reduce el riesgo de lesiones en el tobillo en jugadores de baloncesto. Sin embargo, los mecanismos de protección de lesión proporcionados por las órtesis durante el juego de baloncesto aún son desconocidos. Objetivos: Analizar el efecto del uso de órtesis de tobillo lace-up (con cordón) y de un protocolo de ejercicio que simuló la intensidad del juego de baloncesto sobre la fuerza de reacción del suelo (FRS) durante saltos verticales específicos del baloncesto. Métodos: Once jugadores de baloncesto del sexo masculino con menos de 18 años realizaron 48 saltos verticales, con y sin órtesis de tobillo, durante un protocolo de ejercicios compuesto por cuatro períodos de 10 minutos, que simularon el perfil de actividad e intensidad del juego de baloncesto, así como los intervalos típicos entre los períodos. Las FRS mediolaterales (variables: mayores picos medial y lateral) y verticales (variables: pico vertical, pico de impulso, impulso en 50 ms de aterrizaje, tasa de sobrecarga y altura del salto) fueron medidas durante las fases de despegue y aterrizaje de todos saltos realizados en el protocolo de ejercicio. Resultados: El uso de órtesis redujo la FRS mediolateral en todos los períodos analizados, durante las fases de despegue y aterrizaje (P < 0,05), sin afectar la FRS vertical (P > 0,05). La FRS mediolateral y vertical (picos mediolateral y vertical de despegue, picos mediolaterales de aterrizaje, pico de impulso de aterrizaje, tasa de sobrecarga en el despegue y aterrizaje) aumentaron significativamente durante cuatro períodos subsiguientes de 10 minutos (P < 0,05). Sin embargo, para la FRS mediolateral, el aumento a lo largo del tiempo fue mayor sin el uso de órtesis. Conclusiones: El uso de órtesis de tobillo redujo la FRS mediolateral en el miembro inferior, mientras que hubo un aumento progresivo de la carga externa aplicada al cuerpo durante los saltos en los períodos subsiguientes del protocolo de ejercicios con la misma intensidad del juego de baloncesto. Nivel de evidencia I; Ensayo clínico aleatorizado.

RESUMO Introdução: O uso de órtese de tornozelo reduz o risco de lesões no tornozelo em jogadores de basquetebol. No entanto, os mecanismos de proteção de lesão fornecidos pelas órteses durante o jogo de basquetebol ainda são desconhecidos. Objetivos: Analisar o efeito do uso de órtese de tornozelo lace-up (com cordão) e de um protocolo de exercício que simulou a intensidade do jogo de basquetebol sobre a força de reação do solo (FRS) durante saltos verticais específicos do basquetebol. Métodos: Onze jogadores de basquetebol do sexo masculino com menos de 18 anos realizaram 48 saltos verticais, com e sem órtese de tornozelo, durante um protocolo de exercícios composto por quatro períodos de 10 minutos, que simularam o perfil de atividade e intensidade do jogo de basquetebol, assim como os intervalos típicos entre os períodos. As FRSs mediolaterais (variáveis: maiores picos medial e lateral) e verticais (variáveis: pico vertical, pico de impulso, impulso em 50 ms da aterrissagem, taxa de sobrecarga e altura do salto) foram medidas durante as fases de decolagem e aterrissagem de todos os saltos realizados no protocolo de exercício. Resultados: O uso de órtese reduziu a FRS mediolateral em todos os períodos analisados, durante as fases de decolagem e aterrissagem (P < 0,05), sem afetar a FRS vertical (P > 0,05). A FRS mediolateral e vertical (picos mediolateral e vertical de decolagem, picos mediolaterais de aterrissagem, pico de impulso de aterrissagem, taxa de sobrecarga na decolagem e aterrissagem) aumentaram significativamente durante quatro períodos subsequentes de 10 minutos (P < 0,05). No entanto, para a FRS mediolateral, o aumento ao longo do tempo foi maior sem o uso de órtese. Conclusões: O uso de órtese de tornozelo reduziu a FRS mediolateral no membro inferior, enquanto houve um aumento progressivo da carga externa aplicada ao corpo durante os saltos nos períodos subsequentes do protocolo de exercícios com mesma intensidade do jogo de basquetebol. Nível de evidencia I; Estudo clínico randomizado .

Evaluation of eye, head and trunk coordination during target tracking tasks.

This study tested the feasibility of a method to synchronise and to evaluate eye, head and trunk movement patterns during target tracking tasks performed by 10 subjects. A projected central target was randomly repositioned at 40° and 70° of rotation to the left and right. Subjects were instructed to change gaze as quickly as possible. Head and trunk motion was measured using a motion analysis system, and eye movement was measured using an eye-tracker; all data were synchronised. For healthy subjects, the eye moved faster than the head, there was no trunk movement and the head moved more than the eye to reach further displaced targets. The method tested was feasible, and it could be used to evaluate eye, head and trunk movement patterns of subjects with injuries such as whiplash and concussions. Practitioner Summary: Studies of eye, head and trunk movements using synchronised methods are needed. We tested the feasibility of a method to synchronise and evaluate eye, head and trunk movement patterns. The method tested was feasible, and it could be used to evaluate movement patterns of subjects with injuries such as whiplash.

Does wearing unstable shoes reduce low back pain and disability in nurses? A randomized controlled pilot study.

OBJECTIVE: To evaluate if wearing unstable shoes reduces low back pain and disability in nurses. DESIGN: A randomized controlled trial. SETTING: Hospitals and homecare. SUBJECTS: A total of 20 matched female registered nurses with low back pain. The mean (standard deviation) age was 31 years (5) for the control and 34 years (6) for the intervention group; height was 161 cm (5) and 165 cm (7), respectively. INTERVENTIONS: The intervention group received unstable shoes at Week 2 to wear for at least 36 h/week for a month. MAIN MEASURES: The Oswestry Low Back Pain Disability Questionnaire and a visual analogue pain scale. RESULTS: The mean (standard deviation) pain level was 6 (1) at baseline vs. 6 (2) at Week 6 for the control group, and 5 (1) vs. 1 (1) for the intervention group. The mean (standard deviation) disability level was 31% (9) at baseline vs. 28% (7) at Week 6 for the control, and 27% (12) vs. 13% (5) for the intervention group. There were no significant changes over time on pain or disability levels for the control group. The intervention group reported lower levels of pain on Weeks 4 (mean difference ⩾-1.4, p ⩽ 0.009) and 6 (mean difference ⩾-3.1, p < 0.001). Disability levels were also lower on Weeks 4 (mean difference = -4.5%, p NS) and 6 (mean difference = -14.1%, p = 0.020). CONCLUSIONS: Wearing unstable shoes reduced low back pain and disability in nurses and might be helpful as part of the back pain rehabilitation process.

Work-related musculoskeletal disorders among physical therapists: A systematic review.

Physical therapists (PTs) perform demanding tasks that can lead to work-related musculoskeletal disorders (WMSD), but the rates and characteristics of WMSD among PTs are not well known. The objective of this systematic review of the literature was to integrate the information published on the prevalence, types, and risks for WMSD among PTs. Four databases were searched using combinations and synonyms for WMSD, discomfort, symptoms, and PTs. Two reviewers independently searched and screened peer-reviewed articles published in English evaluating WMSD in PTs; agreement between reviewers was evaluated. From 867 unduplicated articles, 32 were eligible and included. Up to 90% of PTs have WMSD during their careers; 50% experience WMSD within 5 years of practice. Low back was the body part most commonly affected. Female PTs and PTs working in hospitals have higher prevalence of WMSD. WMSD are associated with PTs' age, gender, specialty and job tasks. Performing manual therapy, lifting and transferring patients are tasks commonly associated with PTs' developing WMSD. The body parts affected differed by specialty and tasks. The findings presented in this review are useful to inform future research, quality improvement, and educational programs to reduce the rates of WMSD among PTs.

Work-related musculoskeletal disorders among physical therapists: an online survey.

PURPOSE: To evaluate the rates and characteristics of musculoskeletal disorders (MSDs) in physical therapists (PTs) according to their specialty and setting. METHOD: Participants completed an online questionnaire including 15 demographic questions, 7 work-related and 8 injury-related questions for 9 different body parts. RESULTS: Complete responses were obtained from 121 PTs; 96% reported MSD symptoms during the previous 12 months, 64% affecting at least 3 body parts. The body parts with the highest prevalence of symptoms were the low back (66%) and the neck (61%). For PTs specialized in acute care, geriatrics and pediatrics, the body part most commonly affected was the low back, while for PTs specialized in orthopedics and neurology, the body part most commonly affected was the neck. Regarding work settings, the low back was the most commonly affected for PTs working in skilled nursing facilities, outpatient clinics and hospitals, and the neck in PTs working in academic and home health settings. CONCLUSIONS: MSDs are common among PTs; the body parts most often affected were the low back and neck. The prevalence and body parts affected varied by practice setting and specialty area. The findings can help informing the design of evidence-based rehabilitation, prevention, training and educational programs. IMPLICATIONS FOR REHABILITATION: Rehabilitation of injured physical therapists needs to address the symptoms of the multiple body parts that are usually affected (e.g. back, wrists and hands). Rehabilitation of injured physical therapists needs to take into consideration their job demands, practice setting and specialty area. The findings can inform the design of rehabilitation, prevention, training and educational programs for physical therapists.

The influence of accuracy constraints on EMG and kinetic variables during gait initiation.

[Purpose] This study investigated the effects of accuracy constraints (targets) placed on the stepping-limb heel-strike (HS) on the electromyogram (EMG) and ground reaction forces (GRFs) during gait initiation. [Subjects and Methods] Twenty healthy subjects (29.2 ± 2.9 years) were asked to begin walking or stepping over a 10-cm-high obstacle at a fast speed. A 3-cm-diameter target was placed on the ground to dictate the position and accuracy of the stepping-limb HS. [Results] The results showed that the initiation velocity increase in the no-target conditions was due to modulation of the stance- and stepping-limb GRFs and a corresponding increase in the tibialis anterior (TA) activities of both limbs before stepping-limb toe-off. This was achieved by significantly increasing the stepping- and stance-limb TAEMG1 (determined between the onset of movement and time to peak anteroposterior (A-P) GRF of the stepping- and stance- limb) for the no-target conditions. It seems, therefore, that TAEMG1 and the slope to stepping-limb peak A-P GRF contributed to the intended velocity of initiation. [Conclusion] These data indicate that gait initiation and/or stepping over an obstacle may prove to be tasks by which motor control can be measured. The present study provides insight into the working mechanisms of the stepping and stance limbs and shows a clear need to further investigate whether the intact or affected limb should be used to initiate gait during rehabilitation and prosthetic training.

Kinesio Taping effects on knee extension force among soccer players

Background : Kinesio Taping (KT) is widely used, however the effects of KT on muscle activation and force are contradictory. Objective : To evaluate the effects of KT on knee extension force in soccer players. Method: This is a clinical trial study design. Thirty-four subjects performed two maximal isometric voluntary contractions of the lower limbs pre, immediately post, and 24 hours after tape application on the lower limbs. Both lower limbs were taped, using K-Tape and 3M Micropore tape randomly on the right and left thighs of the participants. Isometric knee extension force was measured for dominant side using a strain gauge. The following variables were assessed: peak force, time to peak force, rate of force development until peak force, time to peak rate of force development, and 200 ms pulse. Results : There were no statistically significant differences in the variables assessed between KT and Micropore conditions (F=0.645, p=0.666) or among testing sessions (pre, post, and 24h after) (F=0.528, p=0.868), and there was no statistical significance (F=0.271, p=0.986) for interaction between tape conditions and testing session. Conclusion: KT did not affect the force-related measures assessed immediately and 24 hours after the KT application compared with Micropore application, during maximal isometric voluntary knee extension. .

Kinesio Taping effects on knee extension force among soccer players.

BACKGROUND: Kinesio Taping (KT) is widely used, however the effects of KT on muscle activation and force are contradictory. OBJECTIVE: To evaluate the effects of KT on knee extension force in soccer players. METHOD: This is a clinical trial study design. Thirty-four subjects performed two maximal isometric voluntary contractions of the lower limbs pre, immediately post, and 24 hours after tape application on the lower limbs. Both lower limbs were taped, using K-Tape and 3M Micropore tape randomly on the right and left thighs of the participants. Isometric knee extension force was measured for dominant side using a strain gauge. The following variables were assessed: peak force, time to peak force, rate of force development until peak force, time to peak rate of force development, and 200 ms pulse. RESULTS: There were no statistically significant differences in the variables assessed between KT and Micropore conditions (F=0.645, p=0.666) or among testing sessions (pre, post, and 24h after) (F=0.528, p=0.868), and there was no statistical significance (F=0.271, p=0.986) for interaction between tape conditions and testing session. CONCLUSION: KT did not affect the force-related measures assessed immediately and 24 hours after the KT application compared with Micropore application, during maximal isometric voluntary knee extension.

Temporo-spatial gait parameters during street crossing conditions: a comparison between younger and older adults.

Most traffic accidents involving pedestrians happen during street crossing. Safe street crossing by older adults requires complex planning and imposes high cognitive demands. Understanding how street crossing situations affect younger and older adults' gait is important to create evidence-based policies, education and training. The objective of this study was to develop and test a method to evaluate temporo-spatial gait parameters of younger and older adults during simulated street crossing situations. Twenty-two younger (25±2 years old) and 22 older adults (73±6 years old) who lived independently in the community completed 3 walking trials at preferred gait speed and during simulated street crossing with regular and with reduced time. There were significant differences between groups (p<0.001) and conditions (p<0.001). Older adults' street crossing walking speed was higher than their preferred speed (p<0.001). Gait during simulated street crossing resulted in significant and progressive gait changes. The methods developed and tested can be used to (1) evaluate if people are at risk of falls and accidents during street crossing situations, (2) to compare among different groups, and (3) to help establish appropriate times for older pedestrians to cross streets safely. The current time to cross streets is too short even for healthy older adults.

Limits of Stability and Adaptation to Wearing Rocker Bottom Shoes.

BACKGROUND: Stability and balance are fundamental during static and dynamic activities. The effects of wearing rocker bottom sole (RBS) shoes on the limits of stability (LOS) and adaptation to wearing RBS shoes need to be investigated. The objectives of this study were to evaluate the LOS when wearing RBS shoes, and to evaluate if people improve their stability while wearing RBS shoes over time. METHODS: Eleven female subjects with no lower extremity impairments participated in the study. The LOS were tested at baseline and weeks 3 and 6 using a Neurocom SMART EquiTest equipment. Center of pressure (CoP) was determined using force plates, and the center of gravity (CoG) position was estimated from the CoP measures and subjects' anthropometry. Subjects performed a series of tasks that involved leaning in different directions so as to move the vertical projection of their CoG. End-point excursions of the CoG floor projection were calculated as a percentage of the distance between the starting position and the target. Considering the body as an inverted pendulum, we recorded the average angular velocity of the inverted pendulum during the movements and quantified directional control as a percentage of movement toward versus away from the target. Shoe types were compared using paired t tests, and sessions were compared using repeated measures ANOVA. RESULTS: The angular velocities of the inverted pendulum (ie, CoG velocity) were not significantly different between shoe conditions in the front and back directions at baseline (4 ± 3 with RBS vs 5 ± 2 deg/sec with regular shoes, and 4 ± 1 vs 6 ± 4 deg/sec). Front directional control of the CoG was significantly worse with RBS shoes at weeks 3 and 6 ( P < .015). Front end-point excursions were also lower with RBS shoes both at baseline and week 6 ( P < .014). There were no significant changes over time. CONCLUSION: The findings indicate that the LOS were negatively affected by wearing RBS shoes and that people do not improve their stability while wearing these shoes even after a 6-week period of use. CLINICAL RELEVANCE: This study shows that wearing RBS shoes increase instability and the instability remains even after wearing these shoes for six weeks.

Functional and psychosocial status of Haitians who became users of lower extremity prostheses as a result of the 2010 earthquake.

The January 12, 2010 earthquake devastated Port-Au-Prince, the capital of the Republic of Haiti, and its surroundings. Among the 300,000 injured, 1,200 to 1,500 people underwent traumatic /surgical amputations. The purpose of this study was to describe the functional and psychosocial impact of prostheses users who suffered a traumatic lower-limb amputation after the earthquake of 2010 in Haiti. We recruited 140 participants in collaboration with a large health care organization in Port-au-Prince from October 2011 to May 2012. Participants underwent an evaluation of physical impairments and completed questionnaires translated into Haitian Creole. The Trinity Amputation and Prosthesis Experience Scale (TAPES), and the Locomotor Capabilities Index (LCI) were used in this study. The questionnaires were administered verbally in Haitian Creole by a trained staff. We conducted descriptive statistics and t-tests using SPSS for data analysis. Participants had a mean age of 34.9 ± 12.0; 51.4% were women; 48.6% were transfemoral amputees. The mean of TAPES general adjustment (3.65 ± 0.59) and adjust to limitation (3.67 ± 0.86) were higher than the score for the social adjustment (2.58 ± 0.49). The LCI showed over 90% of subjects were physically independent in self-care; fewer were independent walking on uneven ground or inclement weather (69%). The relatively poor social adjustment is consistent with the literature that describes limited acceptance of people with physical disabilities in Haitian society. Prostheses users in Haiti would benefit from a health delivery infrastructure that also addresses the psychosocial reintegration of individuals with physical disabilities.

Coactivación muscular del miembro inferior de jóvenes y ancianos saludables durante la marcha con doble tarea funcional / Coativação muscular dos membros inferiores de jovens e idosas saudáveis durante marcha com dupla tarefa funcional / Lower limb muscle coactivation levels in healthy younger and older adults during functional dual-task gait

The purpose of this study was to investigate the influence of daily cognitive task on stiffness of old and young female adults during the gait. The study included 17 physically active younger and 18 older women, with low risk of falls. The volunteers were asked to walk on the treadmill at two different gait conditions: normal gait and functional dual-task gait. The electromyographic signals were collected of the lower limb muscles. The percentage of coactivation for the tibialis anterior/gastrocnemius lateralis and tibialis anterior/soleus were significantly higher in elderly than in younger in the normal gait and dual-task gait. Our results suggest that the elderly have a greater stiffness in the ankle joint during gait normal and daily dual task gait. Thus, we conclude that challenging cognitively situations during the gait may increase the risk of falls in this population.

O objetivo deste estudo foi investigar a influência de uma tarefa cognitiva cotidiana sobre a coativação muscular de mulheres idosas e jovens durante a marcha. Participaram do estudo 17 mulheres jovens fisicamente ativas e 18 mulheres idosas com baixo risco de quedas. Os voluntários foram orientados a caminhar sobre uma esteira em duas diferentes condições de marcha: marcha normal e marcha com dupla-tarefa cotidiana. Os sinais eletromiográficos foram coletados dos músculos dos membros inferiores. A porcentagem de coativação para tibial anterior/gastrocnêmio lateral e tibial anterior/sóleo foram significativamente maiores em idosos do que em jovens na marcha normal e marcha com dupla-tarefa. Nossos resultados sugerem que os idosos tem maior coativação muscular no tornozelo durante a marcha normal e marcha com dupla tarefa cotidiana. Assim, nós concluimos que situações cognitivamente desafiadoras durante a marcha podem aumentar o risco de quedas em idosos.

El objetivo de este estudio fue investigar la influencia de una tarea cognitiva diaria en la co-activación muscular en ancianos y jóvenes durante la marcha. Los participantes del estudio fueron 17 ancianos y 18 jóvenes físicamente activos con bajo riesgo de caídas. Los voluntarios caminaron sobre una cinta de correr en dos condiciones diferentes: la marcha normal y la marcha con doble tarea cotidiana. Las electromiografía se obtuvo de los músculos de las extremidades inferiores. El porcentaje de co-activación de los tibialis anterior/gastrocnemius lateralis and tibialis anterior /soleus fueron significativamente mayores en los ancianos que en los sujetos jóvenes durante la marcha normal y marcha con doble tarea. Nuestros resultados sugieren que los ancianos tienen un mayor coactivación muscular en el tobillo durante la marcha normal y marcha con doble tarea cotidiana. Por lo tanto, se concluye que las situaciones cognitivamente desafiantes durante la marcha puede aumentar el riesgo de caídas en los ancianos.

Effect of a change in step direction from a forward to a lateral target in response to a sensory perturbation.

The aim of the current study was to investigate the response of healthy older and young adults to a change in step direction from a forward to a lateral target in response to a sensory perturbation. Nine healthy older (75.1±6.7years; age range, 65-81years) and nine young adults (27±3.6years; age range, 23-31years) participated in the study. The sensory perturbation was a visual cue presented at random times while subjects stepped over an obstacle from quiet stance. For both young and elderly subjects there was an abrupt change in the slope of both shear ground reaction forces (GRFs) of the stance limb following the perturbation. The slope and peak of the change in GRFs was greater for the young subjects and the onset significantly earlier (205ms compared to 271ms). Changes in the GRFs were accompanied by an increase in bilateral gluteus medius and stance limb soleus activity. A late visual cue resulted in a delayed response for elderly subjects. These data show that a stepping response to a sensory perturbation was both delayed and of less magnitude for older adults which has implications for fall risk.

Use of a squatting movement as a clinical marker of function after total knee arthroplasty.

OBJECTIVE: The aims of this study were to evaluate weight bearing during standing and 30- and 60-degree squats approximately 1 wk and 2 mos after surgery and determine whether weight bearing during squatting could be a better clinical marker than standing for identifying perceived functional limitation approximately 1 wk after surgery. A further objective was to determine whether age, body mass index, and number of outpatient visits over the course of rehabilitation predicted weight bearing during a squat approximately 2 mos after surgery. DESIGN: The percentage of body weight placed over both limbs during stand and 30- and 60-degree squats in 38 patients (25 women and 13 men) who had primary unilateral knee arthroplasty was determined. An asymmetry index would be used as a marker that could discriminate between those who perceived at least moderate difficulty with functional tasks and those who perceived only slight or no difficulty with functional activities based on the physical function dimension of the Western Ontario McMaster Universities Osteoarthritis index approximately 1 wk after surgery. Stepwise regression was conducted to determine whether clinical characteristics predicted weight-bearing asymmetry at discharge. RESULTS: At initial visit (first observation), and compared with the uninvolved side, individuals placed significantly less body weight over the involved or operated limb for stand and 30- and 60-degree squats (P < 0.0001). Results were similar at last rehabilitation visit (second observation). Identifying at least moderate self-reported difficulty with functional tasks based on the receiver operator characteristic curve for the asymmetry index for the stand position was 0.64, whereas for the 30- and 60-degree squats, the area under the curve was 0.81 and 0.89, respectively. At discharge from rehabilitation, there was a moderate to good direct relationship (r = 0.70) between the number of rehabilitation visits completed and the weight-bearing asymmetry index for the 60-degree squat. CONCLUSIONS: On the first outpatient visit, individuals who had primary unilateral knee arthroplasty placed more body weight over the uninvolved side for the three weight-bearing positions. With high probability, the asymmetry index for both squatting angles identified perceived functional difficulty. As rehabilitation visits increased, there was a direct association to improved interlimb weight-bearing symmetry when squatting to 60 degrees.

The effect of a sensory perturbation on step direction or length while crossing an obstacle from quiet stance.

BACKGROUND AND AIMS: The purpose of this study was to investigate the effect of a sensory perturbation on step length and direction while crossing an obstacle from quiet stance. METHODS: Nine healthy adults were asked to step over an obstacle to land on a primary target (normal stepping condition). Following a light signal subjects had to respond as quickly as possible by stepping to secondary targets either forward or diagonal to the primary target. RESULTS: Distinct changes in the slope of the anterior-posterior (Fx) and medial-lateral (Fy) ground reaction forces occurred 176 ms following the light signal. For diagonal stepping stance limb tibialis anterior (TA) and bilateral gluteus medius (GM) were responsible for directing the swing limb to the target. An increase in step length towards the long target was achieved primarily by activation of bilateral GM. CONCLUSIONS: Both EMG and force plate changes suggest that diagonal stepping is a more complex and challenging task than long stepping.

Diabetic neuropathy is related to joint stiffness during late stance phase.

The majority of plantar ulcers in the diabetic population occur in the forefoot. Peripheral neuropathy has been related to the occurrence of ulcers. Long-term diabetes results in the joints becoming passively stiffer. This static stiffness may translate to dynamic joint stiffness in the lower extremities during gait. Therefore, the purpose of this investigation was to demonstrate differences in ankle and knee joint stiffness between diabetic individuals with and without peripheral neuropathy during gait. Diabetic subjects with and without peripheral neuropathy were compared. Subjects were monitored during normal walking with three-dimensional motion analysis and a force plate. Neuropathic subjects had higher ankle stiffness (0.236 N.m/deg) during 65 to 80% of stance when compared with non-neuropathic subjects (-0.113 N.m/deg). Neuropathic subjects showed a different pattern in ankle stiffness compared with non-neuropathic subjects. Neuropathic subjects demonstrated a consistent level of ankle stiffness, whereas non-neuropathic subjects showed varying levels of stiffness. Neuropathic subjects demonstrated lower knee stiffness (0.015 N.m/deg) compared with non-neuropathic subjects (0.075 N.m/deg) during 50 to 65% of stance. The differences in patterns of ankle and knee joint stiffness between groups appear to be related to changes in timing of peak ankle dorsiflexion during stance, with the neuropathic group reaching peak dorsiflexion later than the non-neuropathic subjects. This may partially relate to the changes in plantar pressures beneath the metatarsal heads present in individuals with neuropathy.

Soleus H-reflex modulation and paired reflex depression from prone to standing and from standing to walking.

Patterns of soleus H-reflex modulation as a function of posture, task, and reflex activation history were assessed with three experimental paradigms: lying prone compared with standing unsupported; standing compared with the initiation of walking; and standing compared with the mid stance phase of walking. Paired H-reflexes, 80 ms apart, were evoked under each condition. The paired reflex depression (PRD), the percentage depression of the second H-reflex relative to the first H-reflex, was modulated independently of the first H-reflex across the postures and tasks. These results reveal divergent patterns of segmental reflex modulation and support the idea that segmental reflexes are controlled by multiple mechanisms.

The effect of a dual-task on obstacle crossing in healthy elderly and young adults.

OBJECTIVE: To investigate the effect of a dual-task on step initiation over an obstacle. DESIGN: Repeated-measures design between groups. SETTING: University laboratory. PARTICIPANTS: Ten healthy, community-dwelling elderly adults and 10 healthy young adults. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The effect of a reaction time task on ground reaction forces, toe clearance, and temporal events in stepping over an obstacle. RESULTS: Ground reaction forces of the swing limb before toe-off did not differ between the groups and was not affected by task difficulty. Stepping with a random stimulus after toe-off was the most difficult task, whereas stepping with a predictable stimulus before toe-off was the easiest task. Reaction time and stepping time were greater and toe clearance was less for the elderly subjects. Both groups had a decrease in toe clearance and an increase in reaction time and stepping time as the task became more difficult. CONCLUSIONS: Our findings indicate that even healthy older adults may be at risk for falls in situations where they are engaged in concurrent tasks. The data support the inclusion of dual-task activities in fall prevention programs.

Do people with Parkinson's disease change strategy during unplanned gait termination?

In light of the movement control problems reported for patients with Parkinson's disease (PD), we examined the lower extremity control strategies used by these subjects to stop walking in planned and unplanned situations. We compared how patients with PD and age and gender-matched control subjects modulated lower extremity muscular activity and ground reaction forces during planned and unplanned stoppings. The main findings were that control subjects did not alter muscle activation from planned to unplanned stopping, relative to stance limb kinetic events; they just increased the amplitude of the response (by approximately 800%). We speculate that these data provide preliminary evidence in support of a stereotypical sequence of muscle activation for gait termination whether planned or unplanned. In contrast, subjects with PD appeared to adopt a different strategy when stopping unexpectedly compared to planned stopping. Additional data show that subjects with PD required additional steps to stop walking when stopping unexpectedly as compared to control subjects.

Athletic footwear, leg stiffness, and running kinematics.

CONTEXT: The leg acts as a linear spring during running and hopping and adapts to the stiffness of the surface, maintaining constant total stiffness of the leg-surface system. Introducing a substance (eg, footwear) may affect the stiffness of the leg in response to changes in surface stiffness. OBJECTIVE: To determine if the type of athletic footwear affects the regulation of leg stiffness in dynamic activities. DESIGN: Repeated-measures design. SETTING: Motion analysis laboratory. PATIENTS OR OTHER PARTICIPANTS: Nine healthy adults (age = 28 +/- 6.8 years, mass = 71.6 +/- 12.9 kg) free from lower extremity injuries. INTERVENTION(S): Subjects hopped at 2.2 Hz on a forceplate under 3 footwear conditions (barefoot, low-cost footwear, high-cost footwear). Subjects ran on a treadmill at 2 speeds (2.23 m/s, 3.58 m/s) under the same footwear conditions. MAIN OUTCOME MEASURE(S): Limb stiffness was calculated from forceplate data. Kinematic data (knee and ankle angles at initial contact and peak joint excursion after contact) were collected during running. We calculated 1-way repeated-measures (stiffness) and 2-way (speed by footwear) repeated-measures analyses of variance (running kinematics) to test the dependent variables. RESULTS: A significant increase in leg stiffness from the barefoot to the "cushioned" shoe condition was noted during hopping. When running shod, runners landed in more dorsiflexion but had less ankle motion than when running barefoot. No differences were seen between the types of shoes. The primary kinematic difference was identified as running speed increased: runners landed in more knee flexion. At the ankle, barefoot runners increased ankle motion to a significantly greater extent than did shod runners as speed increased. CONCLUSIONS: Footwear influences the maintenance of stiffness in the lower extremity during hopping and joint excursion at the ankle in running. Differences in cushioning properties of the shoes tested did not appear to be significant.