Can transcranial direct current stimulation improve muscle power in individuals with advanced resistance training experience?

The aim of this study was to investigate the effects of transcranial direct current stimulation (tDCS) on countermovement jump performance (CMJ) in men with advanced strength training experience. Ten healthy male subjects, with advanced strength training and squatting exercise experience, were included. Participants took part in an initial visit to the laboratory to complete anthropometric measurements and CMJ kinematic test-retest reliability. Participants then completed three experimental conditions, 48-72 hours apart, in a randomized, double-blinded crossover design: anodal, cathodal and sham tDCS (2 mA for 20 minutes targeting the motor cortex bilaterally). Participants completed three CMJ tests before and after each experimental condition, with one-minute recovery interval between each test. The best CMJ in each moment was selected for analysis. Two-way (condition by moment) repeated measures ANOVA's were performed for CMJ height, flight time and muscular peak power. Effect sizes and interindividual variability of tDCS responses were also analyzed. There was a significant condition by moment interaction for all outcome measures, with a large pre-post increase in CMJ height, flight time and muscular peak power in the anodal condition. All the participants displayed CMJ performance improvements after the anodal condition. There were no significant differences in both cathodal and sham conditions. Anodal tDCS may be a valuable tool to enhance muscle power related tasks performance, which is extremely relevant for sports that require vertical jumping ability. Anodal tDCS may also be used to support strength training, enhancing its effects on performance-oriented outcome measures.