Comparison of physiological responses and muscle activity during incremental and decremental cycling exercise

Abstract

Objective: To investigate whether a cycling test based on decremental loads (DEC) could elicit higher maximal oxygen uptake (VO˙ 2max) values compared with an incremental test (INC). Design: Nineteen well-trained individuals performed an INC and a DEC test on a single day, in randomized order. Methods: During INC, the load was increased by 20 W·min−1 until task failure. During DEC, the load started at 20 W higher than the peak load achieved during INC (familiarization trial) and was progressively decreased. Gas exchange and electromyography (EMG) activity (n = 11) from 4 lower-limb muscles were monitored throughout the tests. Physiological and EMG data measured at VO˙ 2max were compared between the 2 protocols using paired t tests. Results: VO˙ 2max during the DEC was 3.0% (5.9%) higher than during INC (range 94%–116%; P = .01), in spite of a lower power output (−21 [20] W, P < .001) at VO˙ 2max. Pulmonary ventilation (P = .036) and breathing rate (P = .023) were also higher during DEC. EMG activity measured at VO˙ 2max was not different between tests, despite the lower output during DEC. Conclusions: A DEC exercise test produces higher VO˙ 2max in cycling compared with an INC test, which was accompanied by higher pulmonary ventilation and similar EMG activity. The additional O2 uptake during DEC might be related to extra work performed either by the respiratory muscles and/or the less oxidatively efficient leg muscles.