Gender difference in the proportionality factor between the mass specific VO2max and the ratio between HR(max) and HR(rest).

The maximal rate of oxygen uptake uptake (VO2max) is an important determinant of cardiorespiratory fitness and aerobic performance. Estimation of VO2max from body mass (BM), maximal heart rate (HR (max)) and resting heart rate (HR(rest)) has recently been conducted in a group of well-trained men using the equation: dot VO2max = BM.PF.(HR(max)/HR(rest)), where PF denotes the proportionality factor between HR(max)/HR(rest) and the mass specific VO2max. Fick principle calculations show that PF is given as the product of the mass specific resting oxygen uptake (VO2rest) and the maximum-to-resting ratios for stroke volume and the arterio-venous O2 difference. Due to women's lower mass specific VO2rest, a gender PF difference was hypothesised. In the present study PF was examined in a sample of 27 trained female subjects, and compared with a similar study conducted in men. Significant gender difference was observed in PF, but there was no gender difference when lean BM replaced BM in the PF calculation. Accordingly, VO2max could be estimated indirectly by the following equation: dot VO2max = BM.PF.(HR(max)/HR(rest)), where PF is 14.5 ml.min(-1).kg(-1) for women and 15.3 ml.min(-1).kg(-1) for men. Cross validation showed that the SEE was 0.22 l/min (approximately 6.8 %).