Cardiovascular fitness in premenarcheal girls and young women

Maximal oxygen uptake ((V) over dot O(2)max) in females, expressed as ml x kg(-1) x min(-1), declines steadily during the first three decades of life. The contribution of diminished cardiovascular function to this apparent fa ll in aerobic fitness is unknown, Cardiac responses to maximal cycle exerci se were compared in 24 premenarcheal females (mean age 11.7 years) and 17 y oung adult women (mean age 27.4 years) using Doppler echocardiography. Mean (V) over dot O(2)max was 40 ml x kg(-1) x min(-1) and 34.7 ml x kg(-1) x m in(-1) in the girls and women, respectively (p < 0.05). When (V) over dot O (2)max was expressed relative to allometrically-derived mass(0.52), however , no significant difference was observed in aerobic fitness between the two groups. Similar allometric analyses revealed no significant differences in average maximal cardiac output (10.50 vs 10.07 L x min(-1) BSA(-1.11) for girls and women, respectively) nor maximal stroke volume (53 vs 56 ml BSA(- 1.13) respectively). These findings suggest that 1) allometric scaling is i mportant in eliminating the effects of body size on (V) over dot O(2)max, 2 ) body dimension differences can account for variations in (V) over dot O-2 in young females, and 3) cardiac functional reserve is similar in premenar cheal girls and young adult women.