Bayesian Analysis of the HR-VO₂ Relationship during Cycling and Running in Males and Females

Professional organizations advise prescribing intensity of aerobic exercise using heart rate reserve (%HRR) which is presumed to have a 1:1 relationship with either maximal oxygen uptake (%VO₂max) or %VO₂ reserve (%VO₂R). Even though running and cycling are popular modes of training, these relationships have not been investigated in a group of males and females during both running and cycling. This study evaluated the %HRR-%VO₂max and %HRR-%VO₂R relationships in 41 college-aged males (n = 21) and females (n = 20) during treadmill running and cycling. Heart rate (HR) and VO₂ data were collected at rest and during maximal exercise tests on a treadmill and cycle ergometer. The HR and VO₂ data were analyzed using a Bayesian approach. Both the %HRR-%VO₂max and %HRR-%VO₂R relationships did not coincide with the line of identity in males and females in both treadmill running and cycling. %HRR was closer to %VO₂max than to %VO₂R. There were no significant differences in the intercepts of the %HRR-%VO₂max and %HRR-%VO₂R relationships between males and females during running or cycling, or between running and cycling in males or females. The credible intervals of the intercepts and slopes suggest interindividual variability in the HR-VO₂ relationship that would yield significant error in the prescription of intensity of aerobic exercise for an individual.