The effects of endurance training on muscle oxygen desaturation during incremental exercise tests: a systematic review and meta-analysis.

Objective: Minimum muscle oxygen saturation (SmO ₂ min) measured via near-infrared spectroscopy (NIRS) is a common measure during incremental exercise testing (IET). Our objective was to determine the effects of pre-to-post endurance training on SmO ₂ min (ΔSmO ₂ min) during an IET, using a meta-analysis.
Data Sources: MEDLINE, EMBASE, and SPORTDiscus.
Study Selection: Studies including healthy individuals had to meet the following criteria: (1) endurance training intervention; (2) peripheral muscle NIRS; (3) incremental exercise test pre/post training; (4) SmO ₂ or analogous saturation parameter measured.
Analysis: A PEDro scale was used for risk of bias analysis. A random effect meta-analysis model was used to synthesize the effect of training on ΔSmO ₂ min in individual studies. Statistical heterogeneity was quantified using I ² statistic. A meta-regression was used to estimate the effect of training on the relationship between peak cycling power output (Wpeak), peak pulmonary oxygen uptake (V˙O ₂ peak), and ΔSmO ₂ min. A mixed-effect model was used to estimate categorical variables.
Results: Five studies met the inclusion criteria. No difference in SmO ₂ min was detected following training pre- and post-intervention IETs. A trend for an effect of training on the relationship between Wpeak and ΔSmO ₂ min was observed ( p  = 0.06).
Conclusion: This meta-analysis showed no effects of endurance training on SmO ₂ min during an IET. Our results showed a trend for an effect of training on the relationship between Wpeak and ΔSmO ₂ min, with no effect for V˙O ₂ peak and ΔSmO ₂ min. It is possible that SmO ₂ min is not affected by endurance training, and may be used as a physiological marker for improvements in submaximal performance rather than at peak.
Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
(© 2024 Yogev, Arnold, Nelson, Rosenblat, Clarke, Guenette, Sporer and Koehle.)