PURPOSE: Interest in harmless but effective and easy-to-use methods such as transcranial direct current stimulation (tDCS) and aerobic exercise (AE) to improve cognitive performance in health and disease is growing. Recent research suggests that a combined application of both methods in a multimodal manner (e.g. tDCS before, during or after AE) could lead to improved cognitive improvement. Also tDCS could be a potential tool to modulate sports performance parameters such as perceived exertion and endurance capacity. Thus, here we investigated the impact of tDCS during moderate AE (cycling) on cognition, perceived exertion and power output.METHODS: Data from 101 healthy subjects (average age = 25.31, SD = 2.05, female = 45) were collected in five separate experiments (EXP). Each experiment had a crossover design. EXP-1: anodal tDCS vs. sham during active control (AC); EXP-2: cathodal tDCS vs. sham during AC; EXP-3: AE vs. AC; EXP-4: a. tDCS vs. sham during AE; EXP-5: c. tDCS vs. sham during AE. High-resolution (HD-)tDCS was applied for 25 minutes at 1 mA to the left dorsolateral prefrontal cortex (lDLPFC) using a 4x1 ring electrode configuration (stim electrode at F3). For AE, subjects ran at 75% of their maximum heart rate (moderate intensity) for 25 minutes, while rating of perceived exertion (RPE) and power output (watts) were recorded every four minutes. As a measure of cognition, response inhibition was assessed before and after 20 minutes during the ongoing intervention by a flanker task.RESULTS: A relevant TIME x CONDITION interaction for cognitive performance was only found in EXP-5. Cathodal tDCS during cycling led to a decrease in accuracy whereas accuracy remained constant for sham tDCS during cycling, F(1,23) = 4.58, p = .043, η_p² = .17. A sig. TIME x CONDITION x SEX showed that men were better able to maintain their cycling performance (measured in watts) during the intervention if when receiving anodal tDCS, F(2.32,44.03) = 3.27, p = .041, η_p² = .15. No interaction effects could be demonstrated for RPE and heart rate. CONCLUSIONS: Contrary to current literature only the multimodal, but not unimodal application of tDCS and AE had an influence on cognitive performance. The application of anodal tDCS during moderate AE led to improved cycling performance in men, a finding requiring further consideration in the future.