Muscle force distribution of the lower limbs during walking in diabetic individuals with and without polyneuropathy.

BACKGROUND: Muscle force estimation could advance the comprehension of the neuromuscular strategies that diabetic patients adopt to preserve walking ability, which guarantees their independence as they deal with their neural and muscular impairments due to diabetes and neuropathy. In this study, the lower limb's muscle force distribution during gait was estimated and compared in diabetic patients with and without polyneuropathy. METHODS: Thirty individuals were evaluated in a cross-sectional study, equally divided among controls (CG) and diabetic patients with (DNG) and without (DG) polyneuropathy. The acquired ground reaction forces and kinematic data were used as input variables for a scaled musculoskeletal model in the OpenSim software. The maximum isometric force of the ankle extensors and flexors was reduced in the model of DNG by 30% and 20%, respectively. The muscle force was calculated using static optimization, and peak forces were compared among groups (flexors and extensors of hip, knee, and ankle; ankle evertors; and hip abductors) using MANOVAs, followed by univariate ANOVAs and Newman-Keuls post-hoc tests (p < 0.05). RESULTS: From the middle to late stance phase, DG showed a lower soleus muscle peak force compared to the CG (p=0.024) and the DNG showed lower forces in the gastrocnemius medialis compared to the DG (p=0.037). At the terminal swing phase, the semitendinosus and semimembranosus peak forces showed lower values in the DG compared to the CG and DNG. At the late stance, the DNG showed a higher peak force in the biceps short head, semimembranosus, and semitendinosus compared to the CG and DG. CONCLUSION: Peak forces of ankle (flexors, extensors, and evertors), knee (flexors and extensors), and hip abductors distinguished DNG from DG, and both of those from CG. Both diabetic groups showed alterations in the force production of the ankle extensors with reductions in the forces of soleus (DG) and gastrocnemius medialis (DNG) seen in both diabetic groups, but only DNG showed an increase in the hamstrings (knee flexor) at push-off. A therapeutic approach focused on preserving the functionality of the knee muscles is a promising strategy, even if the ankle dorsiflexors and plantarflexors are included in the resistance training.

The effects of Achilles tendon compliance on triceps surae mechanics and energetics in walking.

Achilles tendon (AT) compliance can affect the generation and transmission of triceps surae muscle forces, and thus has important biomechanical consequences for walking performance. However, the uniarticular soleus (SOL) and the biarticular (GAS) function differently during walking, with in vivo evidence suggesting that their associated fascicles and tendinous structures exhibit unique kinematics during walking. Given the strong association between muscle fiber length, velocity and force production, we conjectured that SOL and GAS mechanics and energetic behavior would respond differently to altered AT compliance. To test this, we characterized GAS and SOL muscle and tendon mechanics and energetics due to systematic changes in tendon compliance using musculoskeletal simulations of walking. Increased tendon compliance enlarged GAS and SOL tendon excursions, shortened fiber operation lengths and affected muscle excitation patterns. For both muscles, an optimal tendon compliance (tendon strains of approximately 5% with maximum isometric force) existed that minimized metabolic energy consumption. However, GAS muscle-tendon mechanics and energetics were significantly more sensitive to changes in tendon compliance than were those for SOL. In addition, GAS was not able to return stored tendon energy during push-off as effectively as SOL, particularly for larger values of tendon compliance. These fundamental differences between GAS and SOL sensitivity to altered tendon compliance seem to arise from the biarticular nature of GAS. These insights are potentially important for understanding the functional consequences of altered Achilles tendon compliance due to aging, injury, or disease.

Effects of a full season on stabilometric parameters of team handball elite athletes / Efeitos da temporada completa em parâmetros estabilométricos em atletas de handebol de elite / Efectos de la temporada completa en parámetros estabilométricos en atletas de balonmano de élite

It is unclear whether athletes change their postural control over the course of a full sport season, or become more asymmetrical with respect to their neuromuscular performance over the same period. The aim of this study was to investigate the effects of a full sport season on the postural control of team handball elite athletes. Ten healthy, elite male team handball players performed bipodal standing (BP) and right and left unipodal standing (UP) during 30s. We used the RMS and speed of the center of pressure to describe postural sway. For the BP task, the sway was lower at the end of the season (p<0.005). For the UP tasks, the sway was lower at the end of the season only for the non-dominant limb (p<0.001). Differences between limbs were observed only at the end of the season (p<0.03). In conclusion, a full team handball season did not lead to deterioration of the athletes' postural control, but by the end of the season, the athletes were more asymmetrical.

Não é claro na literatura científica se atletas mudam seu controle postural ao longo de uma temporada esportiva, ou mesmo se tornam mais assimétricos em relação ao seu desempenho neuromuscular durante o mesmo período. O objetivo deste estudo foi investigar os efeitos de uma temporada esportiva completa no controle postural de atletas de elite do handebol. Dez jogadores de elite de handebol, saudáveis, realizaram a tarefa de postura ereta quieta bipodal (BP) e unipodal direito e esquerdo durante 30 segundos. Foi utilizada a RMS e a velocidade do centro de pressão para descrever a oscilação postural. Para a tarefa de BP, a oscilação foi menor após a temporada esportiva (p < 0,005). Para as tarefas unipodais, a oscilação foi menor após temporada esportiva apenas para o membro não dominante (p < 0,001). Apenas após a temporada, foram observadas diferenças entre os membros (p < 0,03). Em conclusão, uma temporada esportiva para o handebol não levou à deterioração do controle postural dos atletas, entretanto no final da temporada, os atletas apresentaram-se mais assimétricos.

No está claro en la literatura científica si los atletas cambian su control postural a lo largo de una temporada deportiva o incluso si llegan a ser más asimétricas en relación con su rendimiento neuromuscular durante el mismo período. El objetivo de este estudio fue investigar los efectos de una temporada deportiva completa en control postural de deportistas de elite de balonmano. Diez jugadores de balonmano de élite, sanos, llevaron a cabo la tarea de la tranquilidad de la postura de pie bipodal (BP) y unipodal izquierda y derecha durante 30 segundos. RMS fue utilizado y la velocidad del centro de presión para describir el balanceo postural. Para la tarea de BP, la oscilación fue menor después de la temporada de deportes (p < 0,005). Para unipodais las tareas, la oscilación fue menor después de la temporada deportiva para el miembro no dominante (p < 0,001). Solamente después de la temporada, se observaron diferencias entre los miembros (p < 0,03). En conclusión, una temporada de deportes para el balonmano no conduce al deterioro del control postural de los atletas, sin embargo al final de la temporada, los atletas presentaron más asimétrica.