MAXIMAL AEROBIC CAPACITY AND TOTAL BLOOD-VOLUME IN HIGHLY TRAINED MIDDLE-AGED AND OLDER FEMALE ENDURANCE ATHLETES

The primary aim of this study was to test the hypothesis that, relative to age-matched sedentary controls, middle-aged and older female endurance athletes exhibit levels of maximal rate of O-2 consumption (Vo(2max)) similar to those previously reported in male endurance athletes in the same age group and, furthermore, that these high levels of Vo(2max) are associated with elevated total blood volumes. To accomplish this, we measured V-o2max and total blood volume in 13 highly trained female runners and 17 healthy untrained women 50-70 yr of age. The runners had lower (P < 0.001) body mass index and estimated body fat relative to the controls. They also had higher levels of Vo(2max) (2.70 +/- 0.08 vs. 1.74 +/- 0.06 l/min, 48.6 +/- 1.9 vs. 26.5 +/-0.8 ml.kg(-1).min(-1), 58.0 +/- 1.8 vs. 38.8 +/- 1.2 ml.kg fat-free mass(-1).min(-1); all P < 0.001) and total blood volume (4,964 +/- 226 vs. 4,336 +/- 130 ml, P < 0.02; 89 +/- 4 vs. 64 +/- 2 ml/kg, P < 0.001; 106 +/- 4 vs. 96 +/- 3 ml/kg fat-free mass, P < 0.05). The elevated total blood volumes in the runners were due to both higher plasma and erythrocyte volumes. In addition, hematocrit and hemoglobin concentrations were higher in the runners (P < 0.007). Vo(2max) was strongly (P < 0.001) related to total blood volume (r = 0.79), plasma volume (r = 0.76), and erythrocyte volume (r = 0.78) when all were expressed relative to body weight. These findings support the hypothesis that highly trained 50- to 70-yr-old female endurance athletes are capable of exhibiting levels of Vo(2max) similar to 85% higher on average than age-matched healthy untrained controls, consistent with previous findings in trained and untrained men of this age. Furthermore, the high levels of Vo(2max) in the athletes are associated with elevated total blood volumes.