Pushing athletic performance boundaries with anodal transcranial direct current stimulation: an exploratory, pilot, randomized controlled study on strength and inflammation in elite weightlifters

BACKGROUND: Transcranial direct current stimulation (tDCS) has been proposed as a non-invasive neuromodulatory strategy to enhance motor performance and modulate inflammatory responses. However, its effects on strength capacity and physiological stress markers during complex resistance exercises in elite athletes remain underexplored. METHODS: In this exploratory, randomized, sham-controlled pilot study, ten elite male weightlifters (n = 10; active tDCS = 5, sham = 5) received either a single 20-min session of anodal tDCS (2 mA) over the motor cortex or sham stimulation immediately before performing high-load back squats (85% 1RM). Outcomes included repetition number, barbell kinematics, Borg Rating of Perceived Exertion (Borg-RPE), Visual Analogue Scale (VAS) measures, and metabolic and oxy-inflammatory biomarkers (blood glucose, lactate, antioxidant capacity; salivary ROS; urinary IL-6, 8-iso-PGF2α, 8-OH-dG, creatinine, and neopterin). Given the exploratory design and small sample size, intervention effects were analyzed using Mann-Whitney U tests. For outcomes assessed both before and after stimulation, between-group comparisons were performed on change scores (Δ = post - pre). In contrast, mechanical exercise-related variables, which were only collected after stimulation, were directly compared between the active and sham groups. RESULTS: Athletes receiving active tDCS performed a significantly higher number of back squat repetitions and exhibited shorter lift times compared with the sham group (p = 0.024 and p = 0.011, respectively). No significant between-group differences were observed in Borg-RPE, VAS-based subjective measures, or biochemical markers (all p > 0.05). No significant differences were found for the remaining mechanical parameters (all p > 0.05). CONCLUSIONS: A single session of anodal tDCS applied before high-load back squat exercise may be associated with improvements in repetition capacity and lifting efficiency in elite weightlifters. No significant effects were observed on perceived exertion, biomechanical stability measures, or metabolic, oxidative, inflammatory, and renal biomarkers. These preliminary findings suggest that tDCS may represent a promising neuromodulatory adjunct to strength training, warranting confirmation in larger and methodologically powered studies. TRIAL REGISTRATION: None (pilot study).