Water treadmill parameters needed to obtain land treadmill intensities in runners

To establish water treadmill running parameters with shoes (WTR-S) and without water shoes (WTR-NS) needed to obtain known land treadmill running (LTR) cardiorespiratory responses.

Eighteen trained college-aged runners participated in three running conditions (LTR, WTR-S, and WTR-NS) where cardiorespiratory responses were measured. The primary variables of interest were VO2, HR, treadmill speed, and stride frequency (SF). These variables were assessed at 50%, 60%, 70%, and 80% equivalents of land VO2max for all three running conditions.

Data were centered; so in the analysis, intercepts were calculated within the range of data. At an HR of 150 bpm, VO2 was significantly less (P < 0.05) during LTR (34.6 mL·kg(-1)·min(-1)) compared with WTR-S (37.5 mL·kg(-1)·min(-1)) and WTR-NS (37.2 mL·kg(-1)·min(-1)). HR was approximately 7 bpm less during WTR compared with LTR, although the metabolic demand (VO2) was similar. At a treadmill speed of 160.9 m·min(-1), SF during LTR was 23.6 strides per minute greater (P < 0.05) than that during WTR-S and 21.8 strides per minute greater than that during WTR-NS. Wearing water shoes increased VO2 by 4.12 mL·kg(-1)·min(-1) at any given water treadmill speed.

To achieve metabolic oxygen demands equivalent to intensities from 50% to 80% of VO2max on LTR, WTR parameters have to be changed from those used on LTR. WTR is an effective alternative to LTR. Subjects were able to exercise on the water treadmill at intensities equivalent to 80% of their VO2max and 55% to 94% of their land HRmax. Individuals can select a treadmill speed during WTR that elicits an HR of approximately 7 bpm less than their LTR to obtain a cardiorespiratory overload equivalent to 50%, 60%, 70%, and 80% of their land VO2max.