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 ( {Mathematical expression}) with aging. All subjects had similar body fat composition and trained for a similar mileage each week. The parameters tested were {Mathematical expression}, 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 {Mathematical expression} {[ {Mathematical expression} (ml·kg^-1·min^-1)=- 0.439xage+76.5] (n=55, r=-0.768, p<0.001)}. Thus, {Mathematical expression} decreased by 6.9%·decade^-1 along with reductions of HR_max (3.2%·decade^-1, p<0.001) and Q (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 {Mathematical expression} with aging in runners was mainly explained by the central factors (represented by the decline of HR and Q in this study), rather than by the peripheral factor (represented by (C_a -C_-v) O₂).