Effect of aging on human skeletal muscle and motor function

Area of Science:

• Gerontology and Exercise Physiology
• Neuroscience and Aging

Background:

• The American population over 65 is increasing, driving interest in aging research.
• Understanding age-related physiological declines is crucial for maintaining elderly function and independence.

Purpose of the Study:

• To review human studies comparing age-related declines in VO2max, endurance, muscle strength, muscle mass, and motor unit/neuron counts.
• To identify temporal relationships between these declines within the same subjects.
• To highlight knowledge gaps regarding resistance training's effects on age-related neural and muscular losses.

Main Methods:

• Review of existing human studies examining physiological changes with aging.
• Comparison of declines in VO2max, work endurance, muscle strength, muscle cross-sectional area, muscle fiber number, spinal motor neuron number, and motor unit number as a function of age.

Main Results:

• Declines in VO2max and total leg muscle cross-sectional area start in early adulthood.
• Accelerated loss of total muscle area and muscle fiber number begins around age 50.
• Losses in spinal motor neurons and motor units become noticeable around age 60.

Conclusions:

• Distinct temporal patterns exist for age-related declines in cardiorespiratory function, muscle mass, and neuromuscular components.
• Further research is needed to establish precise cause-and-effect relationships by studying these changes within the same individuals.
• Investigating resistance training's impact on age-related motor neuron and muscle fiber loss is essential for promoting elderly function and quality of life.