Discussion
RPE, fatigue
CORTEX
The objective of the present study was to analyze the effects of tDCS on 5000 m running performance, muscle strength and RPE in runners. The results show that 20 min of stimulation with an intensity of 2 mA on the primary motor cortex promoted improved athletic performance by reducing the running time in the Anodal group, with no changes observed for RPE, internal load, and peak torque.The mechanisms of action related to the modulation of neuronal activity induced by tDCS are not yet fully understoodLong-term effects of tDCS may be associated with changes in protein synthesis and gene expressionIn our research, we found that 20 min of pacing can show improvement in running time. However, the results of similar studies still do not show a literature consensus. Recreational runners were found to have no improvement in fatigue after 15 min of stimulation with 2 mA at M1The use of tDCS on the motor cortex has been related to motor development and fatigue toleranceAnother factor that may be related to the lack of improvement in peak torque in our study was the maximum effort performance during the course. It is known that the ability of muscles to generate force becomes progressively impaired during maximum effort and a gradual recovery occurs at the end of physical effortIt is known that RPE and internal load analysis are subjective. Our expectation was to find a significant improvement in the athletes’ RPE as well, considering that there was an improvement in their running performance. The function responsible for the regulation and control of attention is reached by performing an exercise that causes effort and painWe observed self-consciousness as an important point in deciding the stimulation strategy during exercise; in this sense, RPE in each exercise can help the individual better understand the momentary tension caused by physical exertion helping the individual decide to modulate exercise intensityThere are limitations to our study to be considered. We believe that the evaluation of peak torque could have been performed on days other than the 5000 m run, furthermore it could be evaluated immediately after tDCS. If performed on the same day, we suggest longer recovery intervals to gradually return muscle strength after maximal effort. Sample size per group, the lack of crossover design and lack of a third group could be better recommended. We also believe that an investigation with recreational athletes may still be opportune since they present different sensitivities after stimulation because of the lower excitability threshold than trained runners. Further research should be conducted to investigate the chronic effects of tDCS, thus deepening the knowledge regarding the amplitude of responses in performance in these protocols.Finally, the improvements in physical performance related to the acute protocol investigated here can be of great importance for the day-to-day training of athletes. This result implies practical considerations, mainly due to the possibility of access to stimulation and its cost benefit.