Effects Of Repetitive Transcranial Direct Current Stimulation(tDCS) On Anti-fatigue Ability During High-intensity Jumping Exercise

The brain is one of the limiting factors of sports performance in humans. Transcranial direct current stimulation (tDCS) has been used to enhance sports performance by improving motor cortex excitability, but its cumulative effects remain controversial. PURPOSE: To investigate the effects of repetitive tDCS over the primary motor cortex (M1) on anti-fatigue and neuromuscular ability during repeated jumps in the general population. METHODS: Thirty healthy male college students were randomly assigned to two different conditions: anodal (a-tDCS, n = 15, 22.3 ± 1.6 yrs) and sham (sham-tDCS, n = 15, 22.9 ± 2.0 yrs). The a-tDCS group received 2 × 20 min of 2 mA simulation over the M1 on five consecutive days. The sham group received the same stimulation, but the equipment was turned off after 30s of stimulation. Participants performed repeated jumps before the tDCS application, immediately and 1 month after the last session of stimulation. A two-factor repeated measures ANOVA (stimulation condition × time) was used to compare the differences in biomechanical parameters of repeated jumps between two experimental conditions. RESULTS: When comparing the a-tDCS and sham-tDCS groups, the fatigue index was significantly lower (0.29 ± 0.03vs0.34 ± 0.01, p < 0.05). In the a-tDCS group, the total jump height of the repeated jumps was significantly higher after and 1 month after than before (16.41 ± 1.83 vs17.47 ± 2.15 vs 17.44 ± 2.41 m, p < 0.05), while in the sham-tDCS group, the trend of the increase in ground time after the intervention and 1 month after was significantly higher than before (1.78 ± 0.89 vs 2.24 ± 0.98 vs 2.46 ± 0.87, p < 0.05). After stimulation, activation of the rectus femoris (45.96 ± 2.52vs 48.20 ± 3.95, p < 0.05) in the eccentric phase at the end of the test and total jump height (16.41 ± 1.83 vs 17.47 ± 2.15 m, p < 0.05) in the a-tDCS group were significantly higher than the sham-tDCS group. Mean power, lower limb stiffness, and co-activation of lower limb muscles were not significantly different before and after stimulation. CONCLUSIONS: Anodal stimulation at 2 mA applied to the bilateral M1 area for 5 consecutive days can increase the neuromuscular activation during high-intensity jumping exercise, thereby mitigating the decline in exercise performance caused by fatigue, and it is still retained after one month. This work was supported by the National Natural Science Foundation of China (11932013)