Acute effects of transcranial direct current stimulation on cycling performance in trained male athletes

Abstract Objectives The purpose of this study is to examine the effects of applying anodal tDCS (2 mA for 20 min) over the scalp from T3 (anodal-tDCS) to Fp2 (cathodal-tDCS) on the perceptual, physiological and performance responses during maximal incremental and constant-load exercise (CLE) in trained cyclists. Methods Eleven male cyclists performed maximal incremental exercise (MIE) on a cycle ergometer under either tDCS or sham, with power output, heart rate (HR), oxygen uptake (V̇O2), ratings of perceived exertion (RPE) assessed throughout, and blood samples collected before and after MIE. On two separate occasions, nine subjects performed CLE at 62 % of the peak power output followed by a 15 km time trial under either tDCS or sham (n=8 for the time trial). Results HR, V̇O2, RPE and blood samples were collected at regular intervals. There were no differences between tDCS and sham in any variable during the MIE. tDCS elicited a decreased HR (F (4,8)=9.232; p=0.016; η p 2 =0.54), increased V̇O2 (F (4,8)=8.920; p=0.015; η p 2 =0.50) and increased blood non-esterified fatty acids (F (6,8)=11.754; p=0.009; η p 2 =0.60) and glycerol (F (6,8)=6.603; p=0.037; η p 2 =0.49) concentrations during the CLE when compared to sham. tDCS also improved 15 km time trial performance by 3.6 % (p=0.02; d=0.47) without affecting RPE, HR and blood lactate. Conclusions The application of tDCS over the temporal cortex in trained cyclists improved cycling performance during a self-paced time trial but did not enhance performance during maximal incremental exercise. These results are encouraging and merit further investigation of the ergogenic effects of tDCS in trained athletes.