Skeletal muscle function and hypertrophy are diminished in old age

Area of Science:

• Gerontology
• Skeletal Muscle Physiology
• Aging Research

Background:

• Muscle loss and functional decline are hallmarks of aging.
• The capacity for muscle hypertrophy, a key adaptive response, may be impaired in older individuals.

Purpose of the Study:

• To investigate the age-related changes in muscle mass and function.
• To determine if the hypertrophic response to overload is attenuated in aged skeletal muscle.

Main Methods:

• Utilized male Fischer 344 and Fischer 344 x Brown Norway rats across various ages (6, 9, 26, and 33 months).
• Induced muscle hypertrophy via surgical denervation of agonist muscles in the plantaris muscle.
• Measured muscle mass and maximal tetanic force (P(0)) in control and experimental limbs.

Main Results:

• Muscle mass and maximal tetanic force declined by ~30% between 9 and 26 months.
• Fatigue resistance decreased by ~60% in 33-month-old rats.
• At 33 months, hypertrophy induction led to decreased P(0) and a 25% increase in fatigue resistance across all ages.

Conclusions:

• Aging is characterized by a progressive decline in skeletal muscle mass and function.
• The hypertrophic response is diminished in advanced age.
• In aged muscle, a hypertrophic stimulus can exacerbate age-related muscle weakness.