In the realm of ageing research, understanding how mitochondrial function impacts physical performance is crucial. This study, published in the Journal of Cachexia, Sarcopenia and Muscle, investigates the link between mitochondrial respiration in peripheral blood mononuclear cells (PBMCs) and various performance metrics in healthy older adults.
Background
Age-related declines in energy metabolism, muscle strength, and overall physical performance have been associated with reduced mitochondrial respiratory capacity. The authors aimed to clarify the relationship between PBMC respiration and whole-body metabolic flexibility, particularly during submaximal exercise.
Methods
The study involved fifty community-dwelling older adults, aged approximately 70 years. Researchers quantified mitochondrial respiratory capacity using high-resolution respirometry, assessing different states of respiration: ROUTINE, LEAK, and MAX. They also measured substrate oxidation during steady-state treadmill walking at 60% of VO2max using indirect calorimetry, calculating fat and carbohydrate oxidation rates. Muscle strength was evaluated through handgrip dynamometry and one-repetition maximum leg extension tests, while physical function was assessed via gait speed and chair rise time.
Results
The findings revealed significant correlations between higher ROUTINE respiration and better metabolic flexibility, indicated by a lower respiratory exchange ratio (RER) and greater fat utilization. Specifically, ROUTINE respiration was positively correlated with grip strength and gait speed. Adjusted regression analyses further confirmed that higher ROUTINE respiration was associated with increased fat oxidation and faster gait speed.
Cluster analysis identified distinct mitochondrial respiration phenotypes, with the low-respiration group exhibiting lower performance metrics, such as reduced jump height and quadriceps strength, compared to the high-respiration group.
Conclusions
The study concludes that higher PBMC ROUTINE respiration is linked to a more fat-dominant substrate utilization profile during exercise, greater muscle strength, and improved physical performance in older adults. This suggests that PBMC respiratory capacity may serve as a marker for systemic bioenergetic status relevant to exercise performance in ageing.
What this study does not show
This study does not establish a causal relationship between mitochondrial respiration and physical performance, nor does it address the effects of interventions aimed at enhancing mitochondrial function.
Evidence scorecard
- Analytic validity: established
- Clinical validity: partial
- Clinical utility: not established
The evidence is based on primary research involving human subjects.