Are heart rate methods based on ergometer cycling and level treadmill walking interchangeable?

Introduction: The heart rate (HR) method is a promising approach for evaluating oxygen uptake (V˙O2), energy demands and exercise intensities in different forms of physical activities. It would be valuable if the HR method, established on ergometer cycling, is interchangeable with other regular activities, such as level walking. This study therefore aimed to examine the interchangeability of the HR method when estimating V˙O2 for ergometer cycling and level treadmill walking in submaximal conditions. Methods: Two models of HR‐V˙O2 regression equations for cycle ergometer exercise (CEE) and treadmill exercise (TE) were established with 34 active commuters. Model 1 consisted of three submaximal intensities of ergometer cycling or level walking, model 2 included also one additional workload of maximal ergometer cycling or running. The regression equations were used for estimating V˙O2 with seven individual HR values based on 25–85% of HR reserve (HRR). The V˙O2 estimations were compared between CEE and TE, within and between each model. Results: Only minor, and in most cases non-significant, average differences were observed when comparing the estimated V˙O2 levels between CEE and TE. Model 1 ranged from -0.4 to 4.8% (n.s.) between 25–85%HRR. In model 2, the differences between 25–65%HRR ranged from 1.3 to -2.7% (n.s.). At the two highest intensities, 75 and 85%HRR, V˙O2 was slightly lower (3.7%, 4.4%; P