Physiological responses of typical versus heavy weight triathletes to treadmill and bicycle exercise.

A physiological comparison of the responses of typical weight (less than 90 kg) versus heavy weight (greater than 90 kg) male triathletes to maximal treadmill and maximal bicycle exercise was performed to better understand the effects of weight on endurance performance. The heavy triathlete group (90.9 +/- 3.2 kg, mean +/- SD) had significantly (p less than .01) greater percent body fat (11.9 +/- 3.6 vs 7.4 +/- 1.8%) while having significantly (p +/- .01) lower VO2max values expressed in ml.kg-1.min-1 on both the treadmill (55.6 +/- 4.1 vs 69.9 +/- 5.5) and bicycle ergometer (51.9 +/- 3.9 vs 60.5 +/- 6.2) than the typical triathlete group (66.6 +/- 5.9 kg). Analysis of covariance using body fat as the covariate resulted in persistent significant (p less than .02) VO2max (ml.kg-1.min-1) differences between the groups. Statistically significant (p less than .05) differences in running economy existed between the groups (33.7 +/- 2.7 vs 37.1 +/- 1.5 ml.kg-1.min-1; typical vs heavy). The heavy triathletes also had a significantly (p less than .01) shorter treadmill performance time (9.6 +/- 2.3 vs 13.2 +/- 1.7 min) and significantly (p less than .01) lower power per weight ratio on the bicycle ergometer (5.37 +/- 0.48 vs 6.47 +/- 0.59 watts/kg). These findings indicate that the heavy triathlete is at a physiological disadvantage when competing in endurance events and supports the inclusion of a weight category in these events. The reported triathlon results support these physiological findings.