The heart rate method for estimating oxygen uptake : analyses of reproducibility using a range of heart rates from commuter walking

Background. The heart rate method, based on the linear relation between heart rate and oxygen uptake, is potentially valuable to monitor intensity levels of physical activities. However, this depends not least on its reproducibility under standard conditions. This study aims therefore to evaluate the reproducibility of the heart rate method in the laboratory using a range of heart rates associated with walking commuting. Methods. On two different days, heart rate and oxygen uptake measurements were made during three submaximal (model 1) and a maximal exercise intensity (model 2) on a cycle ergometer in the laboratory. 14 habitual walking commuters participated. The reproducibility, based on the regression equations from test and retest and using three levels of heart rate from the walking commuting was analyzed. Differences between the two models were also analyzed. Results. For both models, there were no significant differences between test and retest in the constituents of the regression equations (y-intercept, slope and r-value). Neither were there any systematic differences in estimated absolute levels of VO2 between test and retest for either model. However, some rather large individual differences were seen in both models. Furthermore, no significant differences were seen between the two models in slopes, intercepts and r-values of the regression equations or in the estimated VO2. Conclusion. The heart rate method shows good reproducibility on the group level in estimating oxygen consumption from heart rate – oxygen uptake relations in the laboratory, and based on three levels of heart rate which are representative for walking commuting. However, on the individual level, some large variations were seen.FAA