Neuromuscular Contributions to Age-Related Weakness

BACKGROUND: Declines in skeletal muscle mass and quality are important factors contributing to age-related weakness. Neural activation of agonist and antagonist muscles may also be important contributing factors. METHODS: We conducted a review of the scientific literature on older adults to determine (a) methodologies used to quantify activation, (b) the potential role of agonist and antagonist activation on weakness, and (c) some possible neurophysiological mechanisms that may underlie impaired activation. RESULTS: The cumulative evidence indicates that agonist activation is impaired in some, but not all, older adults and that this impairment contributes to age-related weakness. It is possible that antagonist coactivation also plays a role in age-related weakness, though a definitive link has not been established. CONCLUSION: Future research should focus on improving quantitative measurement and mechanistic understanding of impaired activation with aging.