Effect of body composition on oxygen uptake during treadmill exercise: Body builders versus weight-matched men

Oxygen uptake (VO2) during treadmill exercise is directly related to the sp eed and grade, as well as the participant ts body weight. To determine whet her body composition also affects VO2 (ml . kg(-1). min(-1)) during exercis e, we studied 14 male body builders (M weight = 99 kg, SD = 7; M height = 1 80 cm, SD = 8; M body fat = 8%, SD = 3; M fat free mass = 91 kg, SD = 7) an d 14 weight-matched men (M weight = 99 kg, SD = 9; M height = 179 cm, SD = 5; M body fat = 24%, SD = 5; M fat free mass = 73 kg, SD = 9). Percentage o f body fat, t(13) = 8. 185, p < .0001, and fat free mass, t(13) = 5.723, p < .0001, were significantly different between groups. VO2 was measured by r espiratory gas analysis at rest and during three different submaximal work rates while walking on the treadmill without using the handrails for suppor t. VO2 was significantly greater for the lean, highly muscular men at rest: 5.6 +/- 1 vs. 4.0 +/- 1 ml . kg(-1)min(-1), F(1, 26) = 21.185, p < .001; S tage 1: 1.7 mph/10%, 18.5 +/- 2 vs. 16.1 +/- 2 ml . kg(-1)min(-1), F(1, 26) = 6.002, p < .05; Stage 2: 2.5 mph/12%, 26.6 +/- 3 vs. 23.1 +/- 2 ml . kg( -1). min(-1), F(2, 26) = 7.991, p < .01; and Stage 3: 3.4 mph/14%, 39.3 +/- 5 vs. 33.5 +/- 5 ml . kg(-1). min(-1), F(1, 26) = 7.682, p < .01, body bui lders versus weight-matched men, respectively. However net VO2 (i.e., exerc ise VO2 - rest VO2) was not significantly different between the two groups at any of the matched exercise stages. The findings from this study indicat e that VO2 during weight-bearing exercise performed at the same submaximal work rate is higher for male body builders compared to that measured in wei ght-matched men and that which is predicted by standard equations. These ob served differences in exercise VO2 appear to be due to the higher resting V O2 in highly muscular participants.