VO[subscript 2] Prediction and Cardiorespiratory Responses during Underwater Treadmill Exercise

We compared cardiorespiratory responses to exercise on an underwater treadmill (UTM) and land treadmill (LTM) and derived an equation to estimate oxygen consumption (VO[subscript 2]) during UTM exercise. Fifty-five men and women completed one LTM and five UTM exercise sessions on separate days. The UTM sessions consisted of chest-deep immersion, with 0, 25, 50, 75, and 100% water-jet resistance. All session treadmill velocities increased every 3 min from 53.6 to 187.8 m[middle dot]min[superscript -1]. Cardiorespiratory responses were similar between LTM and UTM when jet resistance for UTM was [greater than or equal to] 50%. Using multiple regression analysis, weight-relative VO[subscript 2] could be estimated as: VO[subscript 2] (mLO[subscript 2][middle dot]kg[superscript -1][middle dot]min[superscript -1]) = 0.19248 [middle dot] height (cm) + 0.17422 [middle dot] jet resistance (% max) + 0.14092 [middle dot] velocity (m[middle dot]min[superscript -1]) - 0.12794 [middle dot] weight (kg) - 27.82849, R[superscript 2] = 0.82. Our data indicate that similar LTM and UTM cardiorespiratory responses are achievable, and we provide a reasonable estimate of UTM VO[subscript 2]. (Contains 4 figures and 3 tables.)