In vivo assessment of muscle mitochondrial function in healthy, young males in relation to parameters of aerobic fitness, 2019, Nieuwenhuizen et al

[Andy]

Abstract
Purpose
The recovery of muscle oxygen consumption (mVO2) after exercise provides a measure of skeletal muscle mitochondrial capacity, as more and better-functioning mitochondria will be able to restore (mVO2) faster to the pre-exercise state. The aim was to measure muscle mitochondrial capacity using near-infrared spectroscopy (NIRS) within a healthy, normally active population and relate this to parameters of aerobic fitness, investigating the applicability and relevance of using NIRS to assess muscle mitochondrial capacity non-invasively.

Methods
Mitochondrial capacity was analysed in the gastrocnemius and flexor digitorum superficialis (FDS) muscles of eight relatively high-aerobic fitness (VO2peak ≥ 57 mL/kg/min) and eight relatively low-aerobic fitness male subjects (VO2peak ≤ 47 mL/kg/min). Recovery of whole body VO2, i.e. excess post-exercise oxygen consumption (EPOC) was analysed after a cycling protocol.

Results
Mitochondrial capacity, as analysed using NIRS, was significantly higher in high-fitness individuals compared to low-fitness individuals in the gastrocnemius, but not in the FDS (p = 0.0036 and p = 0.20, respectively). Mitochondrial capacity in the gastrocnemius was significantly correlated with VO2peak (R2 = 0.57, p = 0.0019). Whole body VO2 recovery was significantly faster in the high-fitness individuals (p = 0.0048), and correlated significantly with mitochondrial capacity in the gastrocnemius (R2 = 0.34, p = 0.028).

Conclusion
NIRS measurements can be used to assess differences in mitochondrial muscle oxygen consumption within a relatively normal, healthy population. Furthermore, mitochondrial capacity correlated with parameters of aerobic fitness (VO2peak and EPOC), emphasising the physiological relevance of the NIRS measurements.

Open access at https://link.springer.com/article/10.1007/s00421-019-04169-8

 

[Jonathan Edwards]

This looks like a useful method for looking at muscle respiration and mitochondrial function in ME. MR spectroscopy can measure more different things I think but near infra red would be much more practical for real time assessments.

 

[JohnTheJack]

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