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Sex differences in neuromuscular fatigue mechanisms in older adults
DescriptionAging is associated with physical and cognitive declines. Fatigability in older adults is more susceptible to cognitive perturbations, indicating that perturbation of the executive functioning of the brain might influence fatigability. We investigated if the prefrontal cortex (PFC) influences the primary motor cortex (M1) during exercise and fatigue by measuring effective connectivity between these areas. Sixty older adults, balanced by sex, performed handgrip contractions at 30% of maximum strength till voluntary exhaustion. Handgrip force, electromyographic activity from the forearm muscles, and activity of the PFC and M1 were recorded. We found that PFC had a significant influence on the M1 during exercise and during fatigue, the influence between the M1 and PFC was bidirectional for males and females. These results show the imperative role of the PFC in exercise endurance in older adults and the neural adaptations employed by older adults to maintain motor performance in the state of fatigue.