Motor performance and aging in males and females.

Advanced aging is accompanied by marked declines in motor performance in males and females including reductions in strength, speed and power of limb muscles that begin as early as midlife (∼>40 years) and accelerate from ∼65 years of age. Low muscle power and strength is exacerbated by increased fatigability with aging of limb muscles during dynamic contraction tasks and larger performance variability (between and within older adults), especially in older females. Starting in midlife, females exhibit earlier and larger age-related reductions in muscle strength and power and athletic performance than males of the same age and this is paralleled by increased prevalence of poor health, frailty, and loss of independence. This review presents evidence of key neural and muscular mechanisms affecting the motor unit, the age-related reductions in motor performance and the increased variability in healthy old and very old males and females. Muscular atrophy, particularly of fast-twitch (Type II) fibers, contractile slowing, degradation of neuromuscular junctions, and impairments in motor unit activation collectively underpin sarcopenia and impaired motor and functional performance among older adults. This review also briefly highlights approaches to understanding the protective effects of physical activity and high-resistance training on the age-related changes in muscle and neural function, even in the oldest adults. Such interventions delay functional declines and emphasize the adaptability of the aging neuromuscular system. Opportunities abound for future research to focus on understanding the specific mechanisms driving neural and muscular degeneration and optimizing exercise strategies to improve neuromuscular health of old males and females.