Test-Retest Reliability of the Microvascular Oxygenation Recovery Response Subsequent to Submaximal Cycling Exercise

Introduction: The purpose was to quantify the within-session and between-session reliability of halftime (HT) and monoexponential curve fitting (EXP) analyses, when assessing the microvascular tissue oxygenation (StO2) recovery response via near-infrared spectroscopy (NIRS). Methods: Seventeen subjects completed a submaximal cycling test and 6-minute cool-down on three occasions. The protocol was completed twice during session 1 and once during session 2. StO2 were collected via NIRS from a randomized vastus lateralis. StO2 response from the last minute of exercise and the entire cool-down was analyzed using HT and EXP. Within-session and between-session reliability were examined by mixed, absolute agreement intraclass correlation coefficients (ICC) and standard error of the measurement (SEM). Results: HT resulted in higher within-session reliability compared to EXP for exercising StO2 (ICCHT=0.920, ICCEXP=0.865, SEMHT=4.9 ∆BSL, SEMEXP=6.2 ∆BSL) and StO2 recovery time (ICCHT=0.772, ICCEXP=0.720, SEMHT=7 sec, SEMEXP=9 sec). Similar between-session reliability for exercising StO2 was observed (ICCHT=0.895, ICCEXP=0.879, SEMHT=5.2 ∆BSL, SEMEXP=5.4 ∆BSL), however HT elicited higher between-session reliability for StO2 recovery time (ICCHT=0.583, ICCEXP=-0.211, SEMHT=7 sec, SEMEXP=15 sec). Conclusions: Due to the better within-session (exercising StO2, StO2 recovery time) and between-session (StO2 recovery time) reliability, practitioners are encouraged to use HT when assessing exercising StO2 and StO2 recovery time.