Effect of experimentally induced muscle pain on neuromuscular control of force production.

PURPOSE: Neural and peripheral effects of induced muscle pain on explosive force production were investigated. METHODS: Nine participants performed two maximal, six explosive, and six electrical stimulations induced (twitches and octets) isometric knee extensions before and after (15 min of rest) receiving an intramuscular injection of hypertonic saline (pain inducer) or isotonic (placebo) infusions in two laboratory visits separated by 7 days. RESULTS: It was observed a reduction of peak torque production in maximal voluntary contraction in both conditions (9.3 and 3.3% for pain and placebo, respectively) and in the rate of torque development in placebo (7%). There was an increase in the rate of torque development for twitch and octets (10.5 and 15.8%, respectively) in the pain condition and peak torque for twitch (12%) in both conditions (as did the total rate of torque development for octets). CONCLUSION: Force production decreases and increases during voluntary and involuntary contractions, respectively, suggesting that acute pain impairs force production via central mechanisms.

Effects of 6-weeks of detraining on functional capacity and rapid torque production in older women.

Mat Pilates has become an attractive alternative exercise among older women, however, despite knowing the importance of regular exercise, interrupting training is a common issue in this population. The aim of the current study was to evaluate the effects of 6-weeks of detraining after a period of 12-weeks of training with Mat Pilates on the functional capacity and neuromuscular performance of the knee extensor muscles in older women. Ten older women (62.6 ± 2.6 years; 1.57 ± 0.05 m height; 69.3 ± 9.2 kg; 27.8 kg/m2 body mass index) volunteered to participate in this study. The study was divided into three periods: a 4-week control period, followed by 12 weeks of Mat Pilates intervention, and a 6-week detraining period. During the intervention, the results showed significant improvements in functional capacity tests (time up and go, time up stairs, time down stairs, and chair sit-and-reach), rate of torque development, and impulse (p < 0.05). After the detraining period, a decrease was observed in the chair sit-and-reach test (p < 0.05) and contractile impulse at intervals 0-30 and 0-50 ms (p < 0.05). We conclude that a 6-week detraining period after a Mat Pilates training protocol was sufficient to cause declines in the chair sit-and-reach test and in the contractile impulse of the knee extensors in the early phase of the torque-time curve (0-30 and 0-50 ms), but not in the other functional capacity tests and neuromuscular parameters evaluated.

Can increased load carriage affect lower limbs kinematics during military gait?

The aim of this study was to investigate if increased load carriage, in male military personnel, can affect the lower limbs kinematics. Twelve male military volunteers from the Portuguese Army were recruited and evaluated in an unloaded and loaded gait condition. Linear kinematics and lower limbs joint angle at heel strike, midstance and toe off were calculated. The stance, swing and double support times were found to be different between load conditions (p < 0.05). There was an interaction between load and limb (p < 0.05) for joint angles, during midstance, with limbs performing different movements in the frontal plane during loaded gait. Load increase had a different effect on the right knee, with a reduction in the abduction (valgus). This study may be beneficial in offering suggestion to improve the performance of gait with load and in an attempt to help prevent possible injuries. Practitioner summary: Increased load can affect lower limbs of male soldiers at the pelvic, hip and knee angles on the frontal plane, which can alter the joint force distribution. While these alterations may indicate protective mechanics, load management procedures should be implemented along with gait monitoring to avoid negative effects in performance.

Does Gait with an Ankle Foot Orthosis Improve or Compromise Minimum Foot Clearance?

The purpose of this study was to investigate if the use of an ankle foot orthosis in passive mode (without actuation) could modify minimum foot clearance, and if there are any compensatory mechanisms to enable these changes during treadmill gait at a constant speed. Eight participants walked on an instrumented treadmill without and with an ankle foot orthosis on the dominant limb at speeds of 0.8, 1.2, and 1.6 km/h. For each gait cycle, the minimum foot clearance and some gait linear kinematic parameters were calculated by an inertial motion capture system. Additionally, maximum hip and knee flexion and maximum ankle plantar flexion were calculated. There were no significant differences in the minimum foot clearance between gait conditions and lower limbs. However, differences were found in the swing, stance and step times between gait conditions, as well as between limbs during gait with orthosis (p < 0.05). An increase in hip flexion during gait with orthosis was observed for all speeds, and different ankle ranges of motion were observed according to speed (p < 0.05). Thus, the use of an ankle foot orthosis in passive mode does not significantly hinder minimum foot clearance, but can change gait linear and angular parameters in non-pathological individuals.

Lifestyle of public transport bus drivers and fare collectors / Estilo de vida de motoristas e cobradores do transporte coletivo / Estilo de vida de condutores y cobradores de transporte colectivo

Objective: Analyze and compare the lifestyle of public transport drivers and fare collectors. Methods: Descriptive, quantitative and cross-sectional study with 88 bus drivers and 75 fare collectors from Florianópolis, Santa Catarina, Brazil. To determine the domain scores (nutrition, physical activity, preventive behavior, social relationship and stress control), the Individual Lifestyle Profile questionnaire and anamnesis were applied. Data collection took place from September to October 2016. The maximum significance level assumed was 5% (p≤0.05). Chi-square test was used to assess the association between responses and job function, and T-test for independent samples was used to compare variables between groups. Results: There was a statistical difference (p>0.001) between bus drivers and fare collectors for age (40,36±8,55; 31,30 ± 8,68 years), time in function (11,47±8,53; 6,14±5,46 years) and time in the transport company (12,8±6,64; 6,35±5,56 years) and there was no association between the answers of the questions and the function performed (p>0.05). Considering the five domains, the workers showed negative behavior for nutrition (p=0.68) and physical activity (p=0.50), and regular behavior for preventive behavior (p=0.09), social relationships (p=0.45) and stress control (p=0.98), without significant differences between groups. Conclusion: Comparing bus drivers and fare collectors, it is noteworthy that there are differences in age, time in function and time in the company, but not in lifestyle and the public transport workers have a negative lifestyle profile in nutrition and physical activity.

Objetivo: Analisar e comparar o estilo de vida dos motoristas e cobradores de tarifa do transporte público. Métodos: Estudo descritivo, quantitativo e transversal, com 88 motoristas de ônibus e 75 cobradores de tarifa de Florianópolis, Santa Catarina, Brasil. Para determinar os escores dos domínios (nutrição, atividade física, comportamento preventivo, relacionamento social e controle do estresse) aplicou-se o questionário Perfil Individual do Estilo de Vida e anamnese. A coleta de dados decorreu entre setembro e outubro de 2016. Considerou-se o nível de significância máximo assumido 5% (p≤0,05) e usou-se o teste qui-quadrado para avaliar a associação entre as respostas e a função do trabalho, e teste T para amostras independentes para comparar as variáveis entre os grupos. Resultados: Houve diferença estatística (p>0,001) entre motoristas de ônibus e cobradores de tarifa para: idade (40,36±8,55; 31,30±8,68 anos), tempo na função (11,47±8,53; 6,14±5,46 anos) e tempo na empresa (12,8±6,64; 6,35±5,56 anos), e não houve associação das respostas das perguntas com a função desempenhada (p>0,05). Considerando os cinco domínios, os trabalhadores apresentaram comportamento negativo para nutrição (p=0,68) e atividade física (p=0,50), e comportamento regular para comportamento preventivo (p=0,09), relações sociais (p=0,45) e controle de estresse (p=0,98), sem diferenças significativas entre grupos. Conclusão: Comparando-se os motoristas de ônibus e os cobradores de tarifa investigados, destaca-se que há diferenças na idade, no tempo na função e no tempo na empresa, mas não no estilo de vida, e que trabalhadores do transporte público possuem um perfil de estilo de vida negativo nos domínios de nutrição e atividade física.

Objetivo: Analizar y comparar el estilo de vida de los conductores y cobradores de tasas del transporte público. Métodos: Estudio descriptivo, cuantitativo y transversal con 88 conductores de autobuses y 75 cobradores de tarifa de Florianópolis, Santa Catarina, Brasil. Se aplicó el cuestionario Perfil Individual del Estilo de Vida y anamnesis para determinar las puntuaciones de los dominios (nutrición, actividad física, conducta de prevención, relacionamiento social y el control del estrés). La recogida de datos se dio entre septiembre y octubre de 2016. Se ha considerado el nivel de significancia máximo del 5% (p≤0,05) y se ha utilizado la prueba de chi-cuadrado para evaluar la asociación entre las respuestas y la función del trabajo, la prueba T para muestras independientes para comparar las variables entre los grupos. Resultados: Hubo diferencia estadística (p>0,001) entre los conductores de autobús y los cobradores de tarifa para: edad (40,36±8,55; 31,30±8,68 años), tiempo de función (11,47±8,53; 6,14±5,46 años) y tempo en la empresa (12,8±6,64; 6,35±5,56 años) y no hubo asociación entre las respuestas de las preguntas y la función realizada (p>0,05). Considerándose los cinco dominios, los trabajadores presentaron conducta negativa para nutrición (p=0,68) y actividad física (p=0,50), y conducta regular para la conducta de prevención (p=0,09), las relaciones sociales (p=0,45) y el control del estrés (p=0,98), sin diferencias significativas entre los grupos. Conclusión: Comparándose los conductores de autobús y los cobradores de tarifa investigados, destacase que hay diferencias en la edad, en el tempo de función y en el tiempo de empresa pero no en el estilo de vida, y que los trabajadores del transporte público tiene un perfil de estilo de vida negativo para los dominios nutrición y actividad física.