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

Objective: To investigate whether a cycling test based on decremental loads (DEC) could elicit higher maximal oxygen uptake DEC test on a single day, in randomized order. Methods: During INC, the load was increased by 20 W center dot 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 VO2max were compared between the 2 protocols using paired t tests. Results: VO2max 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 VO2max. Pulmonary ventilation (P = .036) and breathing rate (P = .023) were also higher during DEC. EMG activity measured at VO2max was not different between tests, despite the lower output during DEC. Conclusions: A DEC exercise test produces higher VO2max 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.

Automated summary

The objective of this study was to investigate whether a cycling test based on decremental loads (DEC) could elicit higher maximal oxygen uptake (VO2max) compared to an incremental load test (INC) on a single day. The results showed that, despite a lower power output, the DEC test produced higher VO2max, higher pulmonary ventilation, and similar EMG activity compared to the INC test.