Estimates of muscular efficiency in competitive and recreational cyclists at similar work intensities and cycling frequencies were examined. Twelve healthy college-age male nonsmoker volunteers were grouped as either competitive (CC; N = 6) or recreational (RC; N = 6) cyclists based upon previous cycling experience. Subjects were studied at pedaling frequencies of 50 and 80 rpm during bouts of graded and submaximal endurance (75% ˙VO2peak) exercise. Between rest and 250 W, we observed no intergroup differences in ˙VO2 (energy input) at either 50 or 80 rpm. Estimates of whole body (gross) muscular efficiency ranged from 15% to 24% in competitive and 13% to 22% in recreational cyclists at 50 rpm but were not different. Delta (Δ) efficiencies ranged from 20% to 34% in competitive and from 21% to 28% in recreational cyclists. Delta efficiency decreased from 27% to 21% in competitive cyclists, from 25% to 21% in recreational cyclists as a function of pedaling frequency, and was not different between groups. Competitive cyclists rode longer at both 50 rpm (27± 5 min vs 14 ± 2 min; P < 0.05) and 80 rpm (35± 4 min vs 20 ± 4 min; P < 0.05). At 50 rpm (3.08± 0.02 l·min-1 vs 2.78 ± 0.05 l·min-1; P < 0.01) and 80 rpm (3.14 ± 0.01 l·min-1 vs 2.7 ± 0.04 l·min-1; P< 0.001), the mean ˙VO2 was also greater in competitive cyclists. Although both groups showed superior endurance at 80 compared with 50 rpm and total work was approximately double competitive cyclists at each pedaling frequency, we observed no differences in whole body muscular efficiency during sustained exercise at 75% ˙VO2peak. Our results suggested that previous cycling experience was of minor importance when comparing cycle ergometer efficiency between these two groups. The increased endurance at higher pedaling frequencies during submaximal exercise is not explained by altered muscular efficiency.
Exercise Physiology Laboratory, Department of Human Biodynamics, University of California at Berkeley, Berkeley, CA 94720-4480
Submitted for publication May 1995.
Accepted for publication May 1996.
Address for correspondence: George A. Brooks, Ph.D., Professor, Exercise Physiology Laboratory, Department of Human Biodynamics, 103 Harmon Gymnasium University of California, Berkeley, CA 94720-4480. E-mail:GBrooks@violet.berkeley.edu