Can transcranial direct current stimulation enhance maximal aerobic performance in runners?

Introduction and Purpose: Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique investigated for exercise performance improvement but the results are mixed, due in part to the paucity of clinical trials 1. This ongoing randomized controlled trial aims at investigating the effects of tDCS on running performance.
Methods: 25 trained runners between 18 and 35 years old completed 4 sessions spaced by one week: an incremental treadmill test to exhaustion to establish individual physiological profiles; two treadmill tests to exhaustion performed at 90% of the maximal aerobic speed following the application of either active or sham 20-minute motor tDCS (in a randomized order) and a control treadmill test to exhaustion at 90%. Primary outcomes were time to exhaustion and ratings of perceived exertion (RPEs) collected every 5 minutes with the Borg scale.
Results: Preliminary results show no significant difference for time to exhaustion and RPE evolution between active and sham conditions at the group level (11.9 min active – 11.7 min sham; p= 082). There is a trend towards runners with lower initial VO2max showing longer time to exhaustion following active tDCS (p=0.07).
Conclusions: Preliminary data suggest no significant effect of one session of motor tDCS in trained runners. The potential influence of baseline athletic level on responsiveness to tDCS needs to be confirmed on the final sample (50 subjects).