Influence of complexity of the task and the level of physical activity in the association between the muscular function and posture of older adults.

Introduction: Postural control involves the coordination of muscle synergies of lower limb for the performance of postural strategies. However, the relationship between muscle function and postural control of older adults with different levels of physical activity has not yet been fully elucidated. The aim of this study was to analyze the influence of muscle function of lower limb on postural control in tasks with disturbance in the visual and somatosensory systems of older adults with different levels of physical activity.

Methods: 61 older adults participated in this study. The assessment of postural control was performed using posturography in tasks with visual and somatosensory systems disturbance. To assess peak torque and mean power of the lower limb, an isokinetic dynamometer was used. A regression test was performed to investigate the association between muscle function and posture. The regression model was adjusted for the level of physical activity.

Results: The complexity of the task and level of physical activity influenced the association between muscle function and postural control. The conditions that involved simultaneous disturbance in the visual and somatosensory systems were the ones that showed the greatest combination of associations, regardless of the stance type.

Conclusion: The ability to produce ankle and hip muscle power seems to be crucial for the postural control of the older adults in tasks that involve reducing the base of support associated with disturbances in the visual and somatosensory system. Physical activity programs for older adults should include strength and power training for the ankle, knee, and hip muscles, with emphasis on hip abductors.