VO2 peak during free swimming using the backward extrapolation of the O2 recovery curve.

The purpose of this study was to evaluate the accuracy and feasibility of estimating oxygen consumption (VO2) during maximal swimming by using the backward extrapolation (BE) of the VO2 recovery curve to time zero. Two series of experiments were conducted. In the first, the validity of the BE method was ascertained by comparing the VO2 peak values obtained during free swimming (Douglas bag technique) with those estimated by the BE method during recovery after the same tests. These results were also compared with VO2 peak measured during uphill treadmill running. VO2 peak measured during maximal free swimming and estimated by the BE method during the recovery period of that test, were not significantly different. No significant difference was found between VO2 peak uphill treadmill running and free swimming. In the second series of experiments, VO2 peak was measured in each of 28 swimmers during uphill running (conventional method) and during unimpeded swimming using the BE method. The mean value was significantly higher during swimming (mean = 3.37) than during running (mean = 3.23). Seventy-five percent of the subjects had higher VO2 peak during swimming. The swimming speed during maximal swimming effort was 10% higher when the BE method was used then when the same subjects were tested by the conventional Douglas bag technique. The BE method is reliable and valid way to measure VO2 peak in maximal swimming and allows the swimmer to use his specifically trained musculature fully.