Ratio scaling of VO2max penalizes women with larger percent body fat, not lean body mass.

Abstract

VO2max expressed in ml.BM-1.min-1 (BM = body mass) has been shown to unduly penalize heavier subjects and instead should be expressed as ml.BM-0.7.min-1. Such findings support the "theory of similarity" (TofS) that proposes the BM exponent should be 2/3 (0.67). The TofS, however, applies better to lean body mass (LBM) that is uninfluenced by fat mass. For young adults, the actual scaling exponent of LBM has yet to be satisfactorily determined. We used allometric scaling (AS) to scale VO2max by BM and LBM in 94 women (age = 27.4 +/- 6.7 yr, BM = 60.3 +/- 8.4 kg). Treadmill VO2max was assessed by indirect calorimetry and LBM was determined from hydrostatic weighing. AS yielded the following exponents (+/- 95% C.I.): BM: 0.61 +/- 0.27, and LBM: 1.04 +/- 0.26. We conclude that VO2max in ml.BM-1.min-1 indeed penalizes heavier women, but this penalty applies only to those who are heavier because of larger percent body fat, not LBM. If one takes the position that excess fatness is undesirable, then from a health and performance perspective, expressing VO2max in ml.BM-1.min-1 may provide an unbiased and useful expression of VO2max in young women.