Exercise intensity is an important aspect of enhancing health-related fitness. Relationships between the percentages of heart rate reserve (%HRR), maximal oxygen uptake (%VO(2max)) and oxygen uptake reserve (%VO₂R) have been proposed as being effective for exercise intensity prescription. The present paper reviewed experimental studies published between 1966 and 2010, which investigated the relationships between the %HRR, %VO(2max) and %VO₂R. The following aspects were focused upon: (a) comparisons of the relationships between %HRR, %VO(2max) and %VO₂R at different exercise intensities; (b) methodological differences in determining resting VO₂ and VO(2max) and associated effects on the above relationships; (c) applicability of the %HRR-%VO(2max) and %HRR-%VO₂R relationships for exercise prescription. Fifteen studies published between 1997 and 2010 met inclusion criteria. Five studies observed the %HRR-%VO₂R relationship, while the others also investigated the %HRR-%VO(2max) relationship. Six studies found that the %HRR was closer to the %VO₂R than the %VO(2max). Most studies did not satisfy the recommended methodological criteria for assessing the resting VO₂, or used incremental test protocols which may have underestimated VO(2max). None investigated the stability of the %HRR-%VO₂R relationship in training conditions, such as during prolonged submaximal exercise. In conclusion, many of the reviewed studies presented methodological limitations that compromised their results in relation to the application of the %HRR-%VO₂R relationship for prescribing aerobic training.