Muscle metabolic function and free-living physical activity

Area of Science:

• Exercise Physiology
• Metabolic Health
• Body Composition

Background:

• Muscle metabolic function during exercise impacts exercise performance and long-term weight management.
• Physical activity is crucial for maintaining a healthy body weight.
• Previous research linked muscle metabolism to weight gain, prompting an investigation into its relationship with daily energy expenditure and physical activity.

Purpose of the Study:

• To investigate the relationship between muscle metabolic function during exercise and free-living energy expenditure and physical activity levels.
• To identify specific muscle metabolic markers associated with physical activity and energy expenditure in premenopausal women.

Main Methods:

• Seventy-one premenopausal women (Black and White) participated in the study.
• Muscle metabolism was assessed using 31P magnetic resonance spectroscopy during isometric plantar flexion.
• Free-living energy expenditure (TEE) was measured via doubly labeled water, with activity-related energy expenditure (AEE) and physical activity (ARTE) calculated subsequently.

Main Results:

• Higher anaerobic glycolytic rate (ANGLY) and muscle phosphomonoester (PME) concentrations at the end of exercise were negatively correlated with TEE, AEE, and ARTE.
• PME and ANGLY were independently associated with ARTE.
• PME was related to perceived exertion (RPE) during maximal exercise, and this relationship mediated the association between PME and ARTE.

Conclusions:

• Physically inactive women exhibit a greater reliance on anaerobic glycolysis during exercise.
• Suboptimal muscle glycolytic function, indicated by elevated PME, may be linked to increased perception of effort during physical activity.
• Muscle metabolic dysfunction could contribute to lower physical activity levels and challenges in weight maintenance.