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.
Keywords: Karvonen heart rate; exercise intensity; exercise prescription; oxygen uptake.