Maximal workload but not peak oxygen uptake is decreased during immersed incremental exercise at cooler temperatures

This study investigated the effects of water temperature on cardiorespiratory responses and exercise performance during immersed incremental cycle exercise until exhaustion.

Ten healthy young men performed incremental cycle exercise on a water cycle ergometer at water temperatures (T _w) of 18, 26 and 34 °C. Workload was initially set at 60 W and was increased by 20 W every 2 min for the first four levels and then by 10 W every minute until the subject could no longer continue.

During submaximal exercise (60–120 W), \(\dot{V}{\text{O}}_{2}\) was greater at T _w = 18 °C than at 26 or 34 °C. Maximal workload was lower at T _w = 18 °C than at 26 or 34 °C [T _w = 18 °C: 138 ± 16 (SD) W, T _w = 26 °C: 157 ± 16 W, T _w = 34 °C: 156 ± 18 W], whereas \(\dot{V}\)O_2peak did not differ among the three temperatures [T _w = 18 °C: 3156 ± 364 (SD) ml min⁻¹, T _w = 26 °C: 3270 ± 344 ml min⁻¹, T _w = 34 °C: 3281 ± 268 ml min⁻¹]. Minute ventilation (\(\dot{V}_{\text{E}}\)) and tidal volume (V _T) during submaximal exercise were higher at T _w = 18 °C than at 26 or 34 °C, while respiratory frequency (f _R) did not differ with respect to T _w.

Peak workload during immersed incremental cycle exercise is lower in cold water (18 °C) due to the higher \(\dot{V}{\text{O}}_{2}\) during submaximal exercise, while the greater \(\dot{V}_{\text{E}}\) in cold water was due to a larger V _T.