Effects of transcranial photobiomodulation on performance and cardiovascular responses in trained cyclists

Background: Transcranial photobiomodulation (PBM) has been proposed to enhance prefrontal cortex (PFC) oxygenation and modulate central mechanisms of fatigue, potentially improving endurance performance. This study investigated the acute effects of PBM on cycling time-trial (TT) performance in well-trained cyclists.Methods: In a randomized, double-blind, crossover design, 18 trained cyclists completed two experimental conditions (PBM and SHAM) prior to a constant-load (CL) test at 5% above the first lactate threshold (LT1) and a 25-min self-paced TT on their own bicycles mounted on an ergometer.Results: No significant condition × time interactions were found for heart rate, blood lactate, ratings of perceived exertion (RPE), or power-related ratios during either the constant-load or TT trials (p > 0.05).Conclusion: Acute transcranial PBM did not influence cycling performance or perceptual and physiological responses in trained athletes. These findings suggest that the applied PBM parameters may have been insufficient to elicit measurable cortical or performance effects. Future research should explore optimized stimulation parameters and chronic application protocols to clarify the potential ergogenic role of PBM in endurance exercise.