A physiological comparison of young and older endurance athletes

Sixteen highly trained masters endurance athletes, 59 ± 6 yr, were compared with 16 young athletes, with whom they were matched on the basis of their training regimens, and with 18 untrained middle-aged men. On echocardiographic evaluation, both groups of athletes had a significantly greater left ventricular volume and mass than the untrained men; there were no significant differences in percent fiber shortening or velocity of fiber shortening among the three groups. Maximum O₂ uptake (VO₂(max)) averaged 15% less in the masters than in the young athletes (58.7 vs. 69 ml.kg^-1.min^-1). When expressed in terms of lean body mass to correct for differences in body fat content, VO₂(max) of the masters athletes was about 60% higher than that of the middle-aged untrained men. Maximum heart rate was 14% lower in the masters athletes than in the young athletes (169 vs. 197 beats/min). The O₂ pulse during maximum exercise (i.e., VO₂(max)/heart rate at VO₂(max) was identical in the masters and young athletes. This finding suggests that the major factor responsible for the lower VO₂(max) of the masters athletes, compared with the young athletes, is their slower heart rate.