Physiological determinants of 10-km performance in highly trained female runners of different ages.

Endurance exercise performance declines with age; however, there is little information on the mechanisms responsible, especially in women. We tested the hypothesis that this performance decline in women is associated with decreases in maximal O2 consumption (VO2max), blood lactate threshold (LT), and running economy (RE). We determined a 10-km race pace, VO2max, LT, and RE in 31 highly trained female runners aged 23-56 yr with similar relative (i.e., age-adjusted) competitive performances. Absolute 10-km race pace declined with age (r = -0.83). Both 10-km performance and age were correlated with VO2max (P < 0.05) and with the running velocity and O2 consumption at LT but not with RE. The runners then were divided into three age groups: group I (23-35 yr), group II (37-47 yr), and group III (49-56 yr). Stepwise regression analyses performed on subjects pooled from groups I and II and from groups II and III indicated that the majority (60%) of the variability in performance for runners aged 23-47 yr was explained by the running velocity at which LT occurred, whereas VO2max explained the majority (74%) of the variability for the runners aged 37-56 yr. We conclude that decreases in VO2max and running velocity at LT are the two physiological phenomena most closely associated with declines in 10-km performance with age in highly trained female runners. However, the contributions of these two mechanisms to the declines in performance are not uniform with advancing age.