Comparison of Physiological Responses and Muscle Activity During Incremental and Decremental Cycling Exercise.

Abstract

To investigate whether a cycling test based on decremental loads (DEC) could elicit higher maximal oxygen uptake (V˙O2max) values compared with an incremental test (INC). Nineteen well-trained individuals performed an INC and a DEC test on a single day, in randomized order. During INC, the load was increased by 20W·min-1 until task failure. During DEC, the load started at 20W 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 V˙O2max were compared between the 2 protocols using paired t tests. V˙O2max 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 V˙O2max. Pulmonary ventilation (P = .036) and breathing rate (P = .023) were also higher during DEC. EMG activity measured at V˙O2max was not different between tests, despite the lower output during DEC. A DEC exercise test produces higher V˙O2max 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.