Examining the effect of transcranial direct current stimulation on the dominant motor cortex in the indirect measurement of physical ability

Background: The effects of transcranial direct current stimulation (tDCS) on specific sports skills have received extensive attention, however, it is difficult to accurately determine its effect on physical performance due to the complexity of the tasks. The objective of this study was to investigate the effects of uni-hemispheric anodal tDCS of the motor cortex (M1) on the indirect measurement of physical ability in healthy men. Methods: Thirteen healthy, right-leg-dominant men aged between 21 and 32 years (26.53 ± 2.73 years) participated in two different experimental conditions in a randomized, single-blinded crossover design: anodal stimulation (a-tDCS) and sham-tDCS (2 mA for 20 minutes targeting the left M1 contralateral to dominant leg). Before and immediately after the tDCS stimulation, participants completed the standing long jump (SLJ) and sidestep test (SST), and their blood pressure and heart rate were checked for the safety of tDCS application. Results: No significant difference was observed between a-tDCS and sham-tDCS (F_(1,24) = 0.02, p = 0.86, η_p² = 0.001) on SLJ. Also, no significant changes in SLJ were observed between pre- and post-stimulation sessions for both conditions (F_(1,24) = 1.18, p = 0.28, η_p² = 0.047). Similarly, SST scores were not significantly different from a-tDCS and sham-tDCS condition (F_(1,24) = 0.57, p = 0.45, η_p² = 0.024). Significant changes in SST were not observed throughout the experiment sessions for both stimulation conditions (F_(1,24) = 0.12, p = 0.73, η_p² = 0.005). Conclusions: The uni-hemispheric a-tDCS applied over the M1 for 20 minutes may not be a valuable tool to obtain the physical performance benefits from the tasks that require bilateral lower limb power output, such as SLJ and SST.