Skeletal Muscle Mitochondrial Function and Fatigability in Older Adults

Area of Science:

• Gerontology
• Exercise Physiology
• Skeletal Muscle Metabolism

Background:

• Aging is associated with increased fatigability and decreased mitochondrial energy production.
• Diminished mitochondrial function may contribute to age-related fatigability.

Purpose of the Study:

• To examine the relationship between skeletal muscle mitochondrial function and fatigability in older adults.
• To investigate the association between quadriceps oxidative capacity and perceived exertion during walking.

Main Methods:

• Thirty older adults (mean age 78.5 years) underwent assessments of fatigability (Borg scale), quadriceps phosphocreatine recovery using (31)P MRS, quadriceps volume, and peak aerobic capacity (VO2peak).
• Calculated measures included ATPmax and quadriceps oxidative capacity (ATPmax·Quadriceps volume).

Main Results:

• Lower quadriceps oxidative capacity (ATPmax·Quadriceps volume) was associated with higher fatigability.
• Individuals with high fatigability utilized a greater proportion of their VO2peak to maintain walking speed.
• Higher ATPmax was linked to lower odds of experiencing high fatigability.

Conclusions:

• Reduced capacity for oxidative phosphorylation in the quadriceps is associated with increased fatigability in older adults.
• This impaired mitochondrial function may contribute to lower peak aerobic capacity and greater perceived exertion.