Fig. 2From: Interchangeability and optimization of heart rate methods for estimating oxygen uptake in ergometer cycling, level treadmill walking and runningLinear regression lines for the estimated V̇O2. The figure is based on the individual V̇O2 values of all participants (n = 24) and the seven intensity levels between 25 and 85%HRR. (a) Model 1 and (b) model 2. For regression equations and r2-coefficients, see Table 4Back to article page