Objective To explore the effect of transcranial direct current stimulation (tDCS) regulating the motor cortex on the performance of endurance exercise with incremental loading. Methods A randomized, double-blind, parallel control design was adopted. Forty healthy adults were randomly divided into real stimulation (lasting 20 min) or sham stimulation groups (30 s slow-rise and 30 s slow-fall stimulation provided within the 1st 1 min only). The multifocal tDCS was used, with seven small electrodes (3.14 cm2 round electrodes) placed in the primary, premotor, and supplementary motor areas to modulate motor cortex excitability. The injection current of a single electrode did not exceed 1 552 μA, and the total currents did not exceed 3 998 μA. Baseline tests on incrementally loading exercises were performed before and after the intervention, with an interval of 48 hours between the two tests. Two-way ANOVA was used to analyze the effects of this tDCS protocol on duration of cycling, power output, and revolution speed. Results All subjects completed the experiment without unexpected adverse effects. The overall accuracy rate of subjective guess was 37.5%. There was no significant difference in duration of cycling or power output between the two groups (P>0.05), and within-group statistics showed an increase in revolution speed after the real stimulation (P=0.012). Conclusions tDCS that targets and modulates the motor cortex can improve the revolution speed during cycling exercise with incremental loading in healthy adults, suggesting that this stimulation protocol may be a potential means of improving exercise efficiency in endurance sports.