30 min of treadmill walking at self-selected speed does not increase gait variability in independent elderly.

Walking is one of the preferred exercises among elderly, but could a prolonged walking increase gait variability, a risk factor for a fall in the elderly? Here we determine whether 30 min of treadmill walking increases coefficient of variation of gait in elderly. Because gait responses to exercise depend on fitness level, we included 15 sedentary and 15 active elderly. Sedentary participants preferred a lower gait speed and made smaller steps than the actives. Step length coefficient of variation decreased ~16.9% by the end of the exercise in both the groups. Stride length coefficient of variation decreased ~9% after 10 minutes of walking, and sedentary elderly showed a slightly larger step width coefficient of variation (~2%) at 10 min than active elderly. Active elderly showed higher walk ratio (step length/cadence) than sedentary in all times of walking, but the times did not differ in both the groups. In conclusion, treadmill gait kinematics differ between sedentary and active elderly, but changes over time are similar in sedentary and active elderly. As a practical implication, 30 min of walking might be a good strategy of exercise for elderly, independently of the fitness level, because it did not increase variability in step and stride kinematics, which is considered a risk of fall in this population.

Local experience of laboratory activities in a BS physical therapy course: integrating sEMG and kinematics technology with active learning across six cohorts.

Introduction: Integrating technology and active learning methods into Laboratory activities would be a transformative educational experience to familiarize physical therapy (PT) students with STEM backgrounds and STEM-based new technologies. However, PT students struggle with technology and feel comfortable memorizing under expositive lectures. Thus, we described the difficulties, uncertainties, and advances observed by faculties on students and the perceptions about learning, satisfaction, and grades of students after implementing laboratory activities in a PT undergraduate course, which integrated surface-electromyography (sEMG) and kinematic technology combined with active learning methods. Methods: Six cohorts of PT students (n = 482) of a second-year PT course were included. The course had expositive lectures and seven laboratory activities. Students interpreted the evidence and addressed different motor control problems related to daily life movements. The difficulties, uncertainties, and advances observed by faculties on students, as well as the students' perceptions about learning, satisfaction with the course activities, and grades of students, were described. Results: The number of students indicating that the methodology was "always" or "almost always," promoting creative, analytical, or critical thinking was 70.5% [61.0-88.0%]. Satisfaction with the whole course was 97.0% [93.0-98.0%]. Laboratory grades were linearly associated to course grades with a regression coefficient of 0.53 and 0.43 R-squared (p < 0.001). Conclusion: Integrating sEMG and kinematics technology with active learning into laboratory activities enhances students' engagement and understanding of human movement. This approach holds promises to improve teaching-learning processes, which were observed consistently across the cohorts of students.

Understanding the effect of window length and overlap for assessing sEMG in dynamic fatiguing contractions: A non-linear dimensionality reduction and clustering.

The Short-Time Fourier transform (STFT) is a helpful tool to identify muscle fatigue with clinical and sports applications. However, the choice of STFT parameters may affect the estimation of myoelectrical manifestations of fatigue. Here, we determine the effect of window length and overlap selections on the frequency slope and the coefficient of variation from EMG spectrum features in fatiguing contractions. We also determine whether STFT parameters affect the relationship between frequency slopes and task failure. Eighty-eight healthy adult men performed one-leg heel-rise until exhaustion. A factorial design with a window length of 50, 100, 250, 500, and 1000 ms with 0, 25, 50, 75, and 90% of overlap was used. The frequency slope was non-linearly fitted as a task failure function, followed by a dimensionality reduction and clustering analysis. The STFT parameters elicited five patterns. A small window length produced a higher slope frequency for the peak frequency (p < 0.001). The contrary was found for the mean and median frequency (p < 0.001). A larger window length elicited a higher slope frequency for the mean and peak frequencies. The largest frequency slope and dispersion was found for a window length of 50 ms without overlap using peak frequency. A combination of 250 ms with 50% of overlap reduced the dispersion both for peak, median, and mean frequency, but decreased the slope frequency. Therefore, the selection of STFT parameters during dynamic contractions should be accompanied by a mechanical measure of the task failure, and its parameters should be adjusted according to the experiment's requirements.

Winter School on sEMG Signal Processing: An Initiative to Reduce Educational Gaps and to Promote the Engagement of Physiotherapists and Movement Scientists With Science.

The application of surface electromyography (sEMG) in neurology is sometimes limited by a scientific background in the use of sEMG. Students frequently use sEMG only when developing their graduate studies. To reduce these barriers, we promoted a free Winter School on sEMG to Latin American students. The school was a 3-day event with theoretical classes and computer programming in Matlab. Lectures were delivered in Portuguese and Spanish to 50 participants. All lectures were recorded and made available on YouTube®. After the School, participants completed a written exam to receive a certificate. The written exam revealed the average effectiveness of 71 ± 20% in the comprehension of topics addressed during the school. Participants rated the School as "excellent" and considered the event as having changed their thoughts about the use of sEMG. Limited mathematical skills or background were the main barriers identified to follow the lectures and to make use of sEMG. We conclude that the Winter School had a positive impact on participant's formation, especially by showing them the importance of continuous involvement with the concepts related to sEMG to become proficient in its use. From the participant's point of view, the activity was excellent and the follow up of the school on YouTube® suggests that combining face-to-face activities followed by the online availability of lectures is a valid strategy to reinforce the learning process and to reduce barriers in the use of sEMG. Whether similar results would be achieved for a paid registration event in an economically developing region, still requires further investigation.

Relationship between Skin Temperature, Electrical Manifestations of Muscle Fatigue, and Exercise-Induced Delayed Onset Muscle Soreness for Dynamic Contractions: A Preliminary Study.

Delayed onset muscle soreness (DOMS) indicates the presence of muscle damage and impairs force production and control. Monitorization of DOMS is useful to improving recovery intervention plans. The magnitude of DOMS may relate to muscle fatigue, which can be monitored by surface electromyography (EMG). Additionally, growing interest has been expressed in determining whether the skin temperature over a muscle group during exercise to fatigue could be a non-invasive marker for DOMS. Here we determine whether skin temperature and manifestations of muscle fatigue during exercise are correlated and can predict DOMS after concentric-eccentric bicep curl exercises. We tested 10 young adults who performed concentric-eccentric bicep curl exercises to induce muscle damage in the biceps brachialis to investigate the relationship between skin temperature and fatigue during exercise and DOMS after exercise. Muscle activation and skin temperature were recorded during exercise. DOMS was evaluated 24 h after exercise. Data analysis was performed using Bayesian regression models with regularizing priors. We found significant muscle fatigue and an increase in skin temperature during exercise. DOMS was observed 24 h after exercise. The regression models showed no correlation of changes in skin temperature and muscle fatigue during exercise with DOMS 24 h after exercise. In conclusion, our preliminary results do not support a relationship between skin temperature measured during exercise and either muscle fatigue during exercise or the ability to predict DOMS 24 h after exercise.

Acute responses to barefoot 5 km treadmill running involve changes in landing kinematics and delayed onset muscle soreness.

BACKGROUND: Barefoot running has gained popularity among physical activity practitioners, but there is a lack of information regarding the acute adaptations to this running technique without supervision. Information about acute adaptations can help to define the best way to insert barefoot running in the routine of runners willing to, and also provide orientation for those people who want to experience this technique. RESEARCH QUESTION: What acute adaptations can be observed among recreational runners exposed to barefoot running? METHODS: Sagittal 2D kinematics, plantar pressure, foot sensitivity and delayed onset muscle soreness were compared between conditions of shod and barefoot running in 13 recreational runners who performed two trials of 5 km treadmill running. RESULTS: We found an acute effect of barefoot running on foot landing that changes from a rearfoot strike to a forefoot strike pattern. This change most likely contributed to the increase in neuromuscular recruitment of calf muscles (i.e. gastrocnemius and soleus) resulting in higher perception of delayed onset muscle soreness. Barefoot running also elicited higher stride cadence. Plantar pressure before and after running revealed higher pressure in the different foot regions after barefoot running. Foot sensitivity increased after running regardless of the footwear condition. CONCLUSION: Barefoot running has acute effects on running technique including higher perception of delayed onset muscle soreness in the 48 h following the exercise. SIGNIFICANCE: Our results highlight the importance of following participants for days after a first session of barefoot running in order to properly manage the acute adaptation periods as well provide precise advices for those trying the barefoot technique.

Can exercise-induced muscle damage be related to changes in skin temperature?

OBJECTIVE: Measurement of skin temperature using infrared thermography has become popular in sports, and has been proposed as an indicator of exercise-induced muscle damage after exercise. However, the relationship between skin temperature and exercise-induced muscle damage is still unclear. Here we set out to investigate the relationship between skin temperature and exercise-induced muscle damage. APPROACH: Twenty untrained participants completed a protocol of exercise for calf muscles. Before and after exercise blood samples were collected to determine creatine kinase and acetylcholinesterase activity. Thermal images were recorded from the exercised muscles to determine skin temperature. Delayed onset muscle soreness was quantified. Correlations between skin temperature and exercise-induced muscle damage were analyzed considering thermal data, creatine kinase and acetylcholinesterase activity at different time moments. MAIN RESULTS: We found delayed onset muscle soreness and an increased creatine kinase activity 48 h after exercise (P < 0.01). Skin temperature parameters (average, maximal, amplitude and difference pre- and post-exercise, immediately after and 48 h after) did not correlate with the creatine kinase responses (P > 0.05). Acetylcholinesterase activity remained stable (P = 0.59). SIGNIFICANCE: We recommend caution when considering changes in skin temperature as dependent on the level of localized and symmetric muscle damage considering calf muscles in untrained participants.

Should we consider steps with variable height for a safer stair negotiation in older adults?

BACKGROUND: Effects of exercise on foot clearances are important. In older adults variations in foot clearances during walking may lead to a fall, but there is a lack of information concerning stair negotiation in older adults. Whether a condition of post exercise changes foot clearances between steps of a staircase in older adults still unknown. OBJECTIVE: To determine differences in clearances when older adults negotiate different steps of a staircase before and after a session of aerobic exercise. METHODS: Kinematics data from 30 older adults were acquired and the toe and heel clearances were determined for each step. Clearances were compared between the steps. RESULTS: Smaller clearances were found at the highest step during ascending and descending, which was not changed by exercise. Smaller clearances suggest higher risk of tripping at the top of the staircase, regardless of exercise. CONCLUSION: A smaller step at the top of a short flight of stairs could reduce chances of tripping in older adults. It suggests that steps with variable height could make stair negotiation safer in older adults. This hypothesis should be tested in further studies.

Acute Effects of Walking Exercise on Stair Negotiation in Sedentary and Physically Active Older Adults.

BACKGROUND: In negotiating stairs, low foot clearance increases the risk of tripping and a fall. Foot clearance may be related to physical fitness, which differs between active and sedentary participants, and be acutely affected by exercise. Impaired stair negotiation could be an acute response to exercise. Here we determined acute changes in foot clearances during stair walking in sedentary (n = 15) and physically active older adults (n = 15) after prolonged exercise. METHODS: Kinematic data were acquired during negotiation with a 3-steps staircase while participants walked at preferred speed, before and after 30 min walking at preferred speed and using a treadmill. Foot clearances were compared before and after exercise and between the groups. RESULTS: Sedentary older adults presented larger (0.5 cm for lead and 2 cm for trail leg) toe clearances in ascent, smaller (0.7 cm) heel clearance in the leading foot in descent, and larger (1 cm) heel clearance in the trailing foot in descent than physically active. CONCLUSION: Sedentary older adults negotiate stairs in a slightly different way than active older adults, and 30 min walking at preferred speed does not affect clearance in stair negotiation.

Leg skin stimulation can be a strategy to improve postural control in the elderly.

Previous studies suggested that skin stimulation by using medical tape glued to the skin over the Achilles tendon can improve postural control in young adults. Such strategy can be valuable if helping to improve postural control in the elderly. Here, we tested the effects of skin stimulation on the postural control of elderly while standing barefoot. Twenty-two voluntary elderly had postural control assessed under different conditions of skin stimulation. Center of pressure was monitored while they stood quietly barefoot on a force plate during standing with and without medical tape glued to the skin over the Achilles tendon. There were effects of skin stimulation for anteroposterior amplitude of center of pressure displacement, mediolateral amplitude of center of pressure displacement, and area of the ellipse for 95% of center of pressure data (P<.05). These results are promising considering that skin stimulation by using medical tape is feasible even for low incoming subjects and possible to self manage for improvements in postural control.

Does skin stimulation compensate impairments in postural control after ankle plantar flexors fatigue?

It has been suggested that skin stimulation using tape glued to the skin over the Achilles tendon helps to improve postural control. It was recently shown that these effects might emerge only after muscle fatigue and not during non-fatigue standing. Here we tested the influence of skin stimulation on postural control before and after fatigue of ankle plantar flexors. Eighteen subjects stood quietly on a force plate while the center of pressure was monitored before and after fatigue of ankle plantar flexors muscles, with and without medical tape glued to the skin over the Achilles tendon. Our results suggested main effects of tape stimulation before fatigue (P<.05) and significant effect of tape stimulation after fatigue only for amplitude of center of pressure in the anteroposterior direction. The novelty of our study is that most of the center of pressure variables are improved by skin stimulation when the ankle plantar flexors are not fatigued. Therefore the benefits of tape stimulation during fatigue condition are questionable.

A biomecânica na educação física escolar: adaptação e aplicabilidade / Biomechanics in the physical education classroom: adaptations and applicability

Embora com aplicações diversas, a Biomecânica do Movimento Humano é geralmente reconhecida na Educação Física (EF) pela sua importância no contexto do esporte. O processo de ensino-aprendizagem da biomecânica deve dar o embasamento necessário para a compreensão das leis da física aplicadas ao movimento, mas também no contexto da escola durante aulas de EF. No entanto, a aplicação da biomecânica na escola não vem sendo explorada nos cursos de licenciatura em EF. O objetivo deste texto é apresentar um ponto de vista sobre formas de adaptar conteúdos da biomecânica ao contexto escolar, por meio de atividades educativas, trazendo exemplos para facilitar a prática do professor de EF. Propõe-se também ilustrar ideias de como promover o contato dos escolares com diferentes conceitos de movimento, matemática, física, biologia, durante as aulas de educação física, contribuindo para um ensino integrativo. Discutimos também a influência da formação, delimitando espaços para conteúdos específicos e os métodos de ensino apropriados para tal abordagem. Observamos que críticas têm sido feitas às abordagens de ensino-aprendizagem da biomecânica no ensino superior, as quais privam o estudante da visualização de conceitos mais práticos e que possam ser aplicados e incorporados no campo de trabalho. Por fim, nosso ponto de vista conclui que, sem dúvidas, os professores de educação física escolar têm dificuldade em aplicar conhecimentos da biomecânica na elaboração de suas aulas. Contudo, essa dificuldade pode resultar tanto de uma formação precária, quanto da dificuldade de ampliar conceitos básicos obtidos durante a formação superior. Nesse sentido, a proposta de ações para divulgar aplicações da biomecânica na escola poderia contribuir positivamente para alteração deste quadro.

Although Biomechanics of Human Movement has several applications for the context of Physical Education area, it is often associated to sports... However, it has been observed that the biomechanics is inadequately presented during physical education graduation, not providing a reflexivespace. In this point of view we aimed at discuss strategies to adapt concepts belonging to biomechanics and applied them to the reality of physical education classrooms considering educative activities in elementary school. Additionally, strategies providing connection between physical education and other disciplines such as mathematics, physical, biology are provided, looking for an integrative learning. To achieve this, the literature was revised considering studies that describe and state the importance ofbiomechanics in the physical education graduation. We also discuss the role of universities in providing a background that would permit to the professional apply the concepts of biomechanics in the professional context as well the space saved to topics strictly related to learning processes. There is discussion about the methods of teaching biomechanics in the physical education faculties limited by few use of practical application, which make difficult to the students transfer the knowledge to the professional actuation. Our point of view concludes that physical education teachers have difficulties to apply the biomechanics knowledge in the context of physical education. However, these difficulties may result from a limited background, but also from the difficult to spread basic concept that are learnt in the graduation and require further study. In this regard, actions aiming at divulgation of biomechanics potential application to the scholar environment would contribute positively to improve the actual condition.