The relationship between mitochondrial function and walking performance in older adults with a wide range of physical...

Area of Science:

• Gerontology
• Exercise Physiology
• Mitochondrial Biology

Background:

• Age-related declines in walking performance are a significant concern in older adults.
• Skeletal muscle mitochondrial dysfunction, characterized by decreased oxidative phosphorylation capacity, may contribute to these declines.
• Mitochondria are crucial for ATP production, supplying over 90% of the energy required for physical activity.

Purpose of the Study:

• To investigate the association between skeletal muscle mitochondrial function and walking performance in older adults.
• To determine if this association differs between higher-functioning, active individuals and lower-functioning, sedentary individuals.

Main Methods:

• Cross-sectional analysis of participants from the Lifestyle Interventions and Independence for Elders (LIFE) Study and the Study of Energy and Aging-Pilot (SEA).
• Objective measurement of physical activity using accelerometers (Actigraph, SenseWear Pro).
• Assessment of skeletal muscle mitochondrial function via phosphocreatine recovery using (31)P magnetic resonance spectroscopy to calculate ATPmax.
• Evaluation of walking performance by measuring time to walk 400m.

Main Results:

• Participants (n=62) were older adults (77.6±5.3 years), predominantly female (64.2%) and white (67.2%).
• Maximal mitochondrial ATP production capacity (ATPmax) was similar between the higher-functioning SEA cohort and the lower-functioning LIFE cohort.
• Higher ATPmax was significantly associated with faster walking performance (shorter walk time) in the higher-functioning SEA cohort (r(2)=0.19, p=0.02), but not in the lower-functioning LIFE cohort (r(2)<0.01, p=0.74).

Conclusions:

• Skeletal muscle mitochondrial function is associated with walking performance in higher-functioning, physically active older adults.
• This association was not observed in lower-functioning, sedentary older adults, suggesting that physical activity levels and overall function may modulate the relationship between mitochondrial health and mobility.
• These findings highlight the importance of maintaining mitochondrial function for mobility in active aging populations.