Verification Phase Confirms V?O2max in a Hot Environment in Sedentary Untrained Males

The verification phase is becoming the norm for confirming V?O-2max during a graded exercise test (GXT), but the use of such testing in untrained participants in the heat remains unknown.PurposeThis study aimed to assess the V?O-2 uptake obtained during a GXT and subsequent verification phase in untrained participants in a hot environment.MethodsTwelve sedentary males completed a GXT followed by a biphasic supramaximal-load verification phase in a hot environment (39 degrees C, 32% relative humidity). Rest between tests occurred in a temperate chamber and lasted until gastrointestinal temperature returned to baseline.ResultsMean verification phase V?O-2max (37.8 +/- 4.3 mL center dot kg(-1)center dot min(-1)) was lower than GXT (39.8 +/- 4.1 mL center dot kg(-1)center dot min(-1); P = 0.03) and not statistically equivalent. Using an individualized analysis approach, only 17% (2/12) of participants achieved a V?O-2 plateau during the GXT. Verification phase confirmed GXT V?O-2max in 100% of participants, whereas the traditional and the new age-dependent secondary V?O-2max criteria indicated GXT V?O-2max achievement at much lower rates (8/12 [67%] vs 7/12 [58%], respectively). Correlational indices between GXT and verification phase V?O-2max were strong (intraclass correlation coefficient = 0.95, r = 0.86), and Bland-Altman analysis revealed a low mean bias of -2.1 +/- 1.9 mL center dot kg(-1)center dot min(-1) and 95% limits of agreement (-5.8 to 1.7 mL center dot kg(-1)center dot min(-1)).ConclusionsVery few untrained males achieved a V?O-2 plateau during GXT in the heat. When conducting GXT in a hot condition, the verification phase remains a valuable addition to confirm V?O-2max in untrained males.