Define Heart Rate (HR) Method -  aerobic capacity?

An alternative method for determining aerobic capacity involves the measurement of heart rate. Heart rate is linearly associated with maximum oxygen uptake. The available methods to predict VO2max consist of HR measurements during the performance at sub-maximal exercise with a treadmill or cycle ergo meter. At least three 3 to 5-minutes of testing at each load has to be performed. Since a fit person shows a lower HR than an unfit one when exercising at the same load (same oxygen uptake) and the maximal KR for each age group is known, the oxygen uptake-HR curve can be drawn to extrapolate maximal HR where it represents VO₂, max. Age and sex differences in HR have to be considered.