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

Objective: Minimum muscle oxygen saturation (SmOmin) 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 SmOmin (ΔSmOmin) 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 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 ΔSmOmin in individual studies. Statistical heterogeneity was quantified using 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˙Opeak), and ΔSmOmin. A mixed-effect model was used to estimate categorical variables.

Results: Five studies met the inclusion criteria. No difference in SmOmin was detected following training pre- and post-intervention IETs. A trend for an effect of training on the relationship between Wpeak and ΔSmOmin was observed (= 0.06).

Conclusion: This meta-analysis showed no effects of endurance training on SmOmin during an IET. Our results showed a trend for an effect of training on the relationship between Wpeak and ΔSmOmin, with no effect for V˙Opeak and ΔSmOmin. It is possible that SmOmin is not affected by endurance training, and may be used as a physiological marker for improvements in submaximal performance rather than at peak.