Effects of physical activity and age on mitochondrial function

Area of Science:

• Gerontology
• Mitochondrial Biology
• Skeletal Muscle Physiology

Background:

• Ageing is theorized to result from accumulating mitochondrial DNA mutations, impairing ATP production and leading to cellular dysfunction.
• While mitochondrial DNA mutations and respiratory chain function decline with age in skeletal muscle, the observed decline in function exceeds that explained by mutation levels.
• This discrepancy suggests other factors contribute to age-related mitochondrial dysfunction.

Purpose of the Study:

• To investigate the influence of chronological age on muscle mitochondria.
• To test the hypothesis that reduced physical activity is a key factor in age-related decline of mitochondrial function.
• To differentiate the effects of ageing from physical activity levels on muscle oxidative metabolism.

Main Methods:

• Studied muscle mitochondria in subjects carefully matched for physical activity levels.
• Assessed parameters of respiratory chain function.
• Measured markers of physical activity, including activity score and handgrip strength.

Main Results:

• In physically active individuals, chronological age showed little correlation with oxidative metabolism.
• Several measures of respiratory chain function correlated significantly with physical activity markers.
• The extent of decline in respiratory chain function was less pronounced when physical activity was controlled.

Conclusions:

• Reduced physical activity is a major contributor to the decline in mitochondrial oxidative capacity during ageing.
• Physical activity can ameliorate, and potentially mask, mitochondrial ageing in skeletal muscle.
• Maintaining physical activity may be crucial for preserving muscle mitochondrial health throughout the lifespan.