Interchangeability and optimization of heart rate methods for estimating oxygen uptake in ergometer cycling, level treadmill walking and running

BACKGROUND: The heart rate (HR) method enables estimating oxygen uptake (V̇O(2)) in physical activities. However, there is a paucity in knowledge about the interchangeability of this method when applied to cycling, walking and running. Furthermore, with the aim of optimization, there is a need to compare different models for establishing HR-V̇O(2) relationships. METHODS: Twenty-four physically active individuals (12 males and 12 females) participated. For each participant, two models of HR-V̇O(2) relationships were individually established in ergometer cycling, level treadmill walking and running. Model 1 consisted of five submaximal workloads, whereas model 2 included also a maximal workload. Linear regression equations were used to estimate V̇O(2) at seven intensity levels ranging between 25 and 85% of heart rate reserve (HRR). The estimated V̇O(2) levels were compared between the exercise modalities and models, as well as with data from a previous study. RESULTS: A high level of resemblance in estimated V̇O(2) was noted between running and cycling as well as between running and walking, with both model 1 and model 2. When comparing walking and cycling, the V̇O(2) levels for given intensities of %HRR were frequently slightly higher in walking with both models (range of significant differences: 5–12%). The variations of the estimated individual V̇O(2) values were reduced when using model 2 compared to model 1, both between and within the exercise modalities. CONCLUSION: The HR method is optimized by more workloads and wider ranges. This leads to overall high levels of interchangeability when HR methods are applied in ergometer cycling, level treadmill walking and running. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12874-022-01524-w.