Verification tests to confirm graded exercise test (GXT) V[Combining Dot Above]O 2max are growing in popularity but the validity and reliability of such testing in the heat remains unknown.

Purpose

To evaluate the validity and reliability of a verification test to confirm GXT V[Combining Dot Above]O 2max in a hot environment.

Methods

Twelve recreationally trained cyclists completed a two-test protocol that included a GXT progressing 20 W·min-1 followed by a biphasic supramaximal-load verification test (1 min at 60% increasing to 110% maximal GXT wattage until failure) in a hot environment (39° C, 32% relative humidity). Rest between tests occurred in a thermoneutral room and was anchored to the duration required for gastrointestinal temperature to return to baseline.

Results

Mean verification test V[Combining Dot Above]O 2max (51.3±8.8 mL·kg-1·min-1) was lower than GXT (55.9±7.6 mL·kg-1·min-1; p = 0.02). Verification tests confirmed GXT V[Combining Dot Above]O 2max in 92% of participants using individual analysis thresholds. Bland-Altman analysis revealed a sizable mean bias (-4.6±4.9 mL·kg-1·min-1) with wide 95% limits of agreement (-14.0 to 5.0 mL·kg-1·min-1) across a range of V[Combining Dot Above]O 2max values. The high coefficient of variation (9.6%) and typical error (±3.48 mL·kg-1·min-1) indicate potential issues of test-retest reliability in the heat.

Conclusions