The American College of Sports Medicine (ACSM) recommends the use of 40%, 60%, 80%, and 85% of maximal oxygen consumption (JOURNAL/mespex/04.02/00005768-199401000-00019/ENTITY_OV0312/v/2017-07-20T222405Z/r/image-pngO2max) as target values in developing exercise prescriptions. Further, the ACSM states that 55%, 70%, 85%, and 90% of maximal heart rate (HRmax) may be used as indices of these respective levels of %JOURNAL/mespex/04.02/00005768-199401000-00019/ENTITY_OV0312/v/2017-07-20T222405Z/r/image-pngO2max for the general population. The current study evaluated this relationship between %HRmax and %JOURNAL/mespex/04.02/00005768-199401000-00019/ENTITY_OV0312/v/2017-07-20T222405Z/r/image-pngO2max in apparently healthy, young adults. Eighty-one men and 81 women between the ages of 18 and 34 engaged in an incremental exercise test to exhaustion. Linear regressions of %HRmax and %JOURNAL/mespex/04.02/00005768-199401000-00019/ENTITY_OV0312/v/2017-07-20T222405Z/r/image-pngO2max were performed on each subject. From these regressions, target values of %HRmax were computed for each individual. Mean percentages of HRmax were 63%, 76%, 89%, and 92% at 40%, 60%, 80%, and 85% of JOURNAL/mespex/04.02/00005768-199401000-00019/ENTITY_OV0312/v/2017-07-20T222405Z/r/image-pngO2max, respectively. At all of these values of %JOURNAL/mespex/04.02/00005768-199401000-00019/ENTITY_OV0312/v/2017-07-20T222405Z/r/image-pngO2max, the values obtained for %HRmax were significantly greater (P < 0.001) than those used by the ACSM. Fitness affected these results, particularly among men. High fit men averaged 2% higher in %HRmax than low fit men at any given value of %JOURNAL/mespex/04.02/00005768-199401000-00019/ENTITY_OV0312/v/2017-07-20T222405Z/r/image-pngO2max.