Cardiovascular changes associated with decreased aerobic capacity and aging in long-distance runners

Fifty-five male runners aged between 30 to 80 years were examined to determine the relative roles of various cardiovascular parameters which may account for the decrease in maximal oxygen uptake ( \(\dot V_{o_{2max} } \) ) with aging. All subjects had similar body fat composition and trained for a similar mileage each week. The parameters tested were \(\dot V_{o_{2max} } \) , maximal heart rate (HR _max), cardiac output (Q), and arteriovenous difference in oxygen concentration (C _a —C _¯v) O₂ during graded, maximal treadmill running. Average body fat and training mileage were roughly 12% and 50 km·week⁻¹, respectively. The average 10-km runtime slowed significantly by 6.0%·decade⁻¹ {[10-km run-time (min)=0.323 x age (years)+24.4] (n=49,r=0.692,p<0.001)}. A strong correlation was found between age and \(\dot V_{o_{2max} } \) {[ \(\dot V_{o_{2max} } \) (ml·kg⁻¹·min⁻¹)=- 0.439xage+76.5] (n=55,r=-0.768, p<0.001)}. Thus, \(\dot V_{o_{2max} } \) decreased by 6.9%·decade⁻¹ along with reductions ofHR _max (3.2%·decade⁻¹, p<0.001) andQ (5.8%·decade⁻¹, p<0.001), while no significant change with age was observed in estimated (C _a —C _¯v) O₂. It was concluded that the decline of \(\dot V_{o_{2max} } \) with aging in runners was mainly explained by the central factors (represented by the decline ofHR andQ in this study), rather than by the peripheral factor (represented by (C _a —C _¯v) O₂).