Tests of performance on a bicycle ergometer have routinely been standardized with pedaling frequencies of up to 60 rpm. Only rarely have higher speeds been used. It may be hypothesized than a higher VO2, more closely approximating the maximum attainable by treadmill running, may be achieved in bicycle ergometry if higher pedal frequencies are used so that premature fatigue of the leg musculature does not obscure the comparison. Even in treadmill running it remains equivocal which combination of speed and grade of running will produce a maximum VO2. Five male subjects performed maximally at pedal frequencies of 60, 80, 100 and 120 rpm and running speeds of 6.0, 6.5, 7.0, and 7.5 mph, on a bicycle and treadmill respectively. Power output on the bicycle and increasing grade sequence on the treadmill were maintained constant for each speed investigated. The highest VO2 attained in each test was measured and compared both within and between the modes of testing. It was confirmed that peak VO2 during bicycle ergometry is significantly less than VO2 max attained in treadmill running. Pedal frequencies of 80 and 100 rpm produced optimal VO2's in ergometry. No differences were noted between VO2's determined at any speed of treadmill running. Subjects preferred 60 or 80 rpm in ergometry and 6.0 and 7.0 mph in treadmill running; 120 rpm and 7.5 mph in bicycling and treadmill running, respectively, were generally disliked.

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