Meta-analysis Of The Comprehensive Effects Of Transcranial Direct Current Stimulation On Physical Fitness In Healthy Athletes And Non-athletes

Transcranial direct current stimulation (tDCS) can potentially improve physical fitness by modulating motor cortex excitability, but its effects with different stimulation parameters in healthy athletes and non-athletes remain controversial. PURPOSE: The purpose of this study is to quantitatively assess the comprehensive effects of transcranial direct current stimulation on physical fitness in healthy athletes and non-athletes. METHODS: Following the PRISMA guidelines, we registered the systematic review and meta-analysis with PROSPERO (CRD42024543696). Studies were systematically searched in journals indexed by databases including PubMed, Embase, Web of Science, Scopus, the Cochrane Library, CNKI, Wanfang, and VIP Database from their inception up to October 2024. We searched for randomized controlled and randomized crossover trials comparing the effects of anodal-tDCS stimulation versus sham-tDCS on physical fitness in healthy athletes and non-athletes. RESULTS: Data from 38 studies involving 709 subjects were included in the meta-analysis. Results revealed that tDCS significantly improved the physical fitness of healthy individuals (SMD = 0.17, p = 0.003, 95%CI: 0.06 ~ 0.29). Specifically, anodal tDCS targeting the primary motor cortex (SMD = 0.20, p = 0.003, 95%CI: 0.07 ~ 0.33), using 1.5 mA or 2 mA (SMD = 0.64, p = 0.0002, 95%CI: 0.30 ~ 0.98; SMD = 0.14, p = 0.03, 95%CI: 0.01 ~ 0.26), for a duration of 20 minutes (SMD = 0.23, p = 0.002, 95%CI: 0.08 ~ 0.38), and with a 35 cm2 electrode patch (SMD = 0.31, p < 0.0004, 95%CI: 0.14 ~ 0.48) resulted in significant improvements in maximum strength (SMD = 0.32, p = 0.01, 95%CI: 0.07 ~ 0.56), explosive force (SMD = 0.27, p = 0.03, 95%CI: 0.03 ~ 0.52), muscle endurance (SMD = 0.47, p < 0.0007, 95%CI: 0.20 ~ 0.74), cardiopulmonary endurance (SMD = 0.51, p < 0.02, 95%CI: 0.08 ~ 0.93), and static balance (SMD = 0.37, p = 0.03, 95%CI: 0.04 ~ 0.71) in both athletes (SMD = 0.25, p = 0.03, 95%CI: 0.02 ~ 0.48) and non-athletes (SMD = 0.15, p = 0.02, 95%CI: 0.02 ~ 0.28). However, no effect was observed on moving speed (SMD = 0.17, p = 0.18, 95%CI: - 0.08 ~ 0.42) and dynamic balance (SMD = 0.06, p = 0.69, 95%CI: - 0.22 ~ 0.33). CONCLUSIONS: tDCS can effectively improve maximum strength, explosive power, muscle endurance, cardiorespiratory endurance, and static balance in healthy athletes and non-athletes. Supported by: This research was funded by the Fundamental Research Funds for the Central Universities (2022QN013, 2024YDXL004), the Research Foundation for Advanced Talents of Beijing Sport University (3101037).