Procedure
pain
CONTRACTION, CORTEX
The study had a randomized, single-blinded, sham-controlled cross-over design. Each elite gymnast participated in three tDCS conditions (i.e., premotor cortex stimulation, cerebellar stimulation, sham stimulation) in between-subject randomized order with one-week interval between sessions. Participants were asked to avoid high-intensity exercise or training for 48 h preceding the respective experimental session.During each session, performance parameters were measured including broad jump, straddle lift to handstand, double legs circle, back hang scale, dips on parallel bars, active shoulder flexibility and sit and reach tests for 10 min before stimulation (1 min for the BJT test, 2 min for the SLHT test, 2 min for the DLCT test, 1 min for the BHST test, 1 min for the ASFT test, 1 min for the SRT test, and 2 min for DPBT test), then participants were seated on a comfortable chair and rested for 30 min until heart rate returned to resting rate. After electrode placement, tDCS was conducted for 20 min. During the last 5 min of tDCS intervention, 10 s EMG maximal isometric contraction signals were recorded for each muscle, after that the 5 s of the best MIVC were selected for each muscle. Then the performance parameters were obtained in the same way, including order, as for the baseline measures, for 10 min. In other words, performance parameters were measured offline (before and after intervention) and EMG parameters were measured online (during stimulation). All participants completed a standardized warm-up before these measures and a cool-down after the testing sessions. At the end of each session, participants were asked to complete a short survey about tDCS-related side effects (e.g. itching, burning, pain) on a 5-point Likert scale using a standard questionnaire