Determination of BDNF Peak Time in Different Types of Exercises

Purpose The purpose of this study was to determine the peak point of BDNF following exercises of different intensities. Method This randomized crossover controlled trial aimed to examine the acute effects of three experimental conditions-high-intensity interval training, long-interval continuous training, and low-intensity continuous training-on serum BDNF and blood lactate levels in healthy young adults aged 18-25 years. All participants completed the three conditions in a randomized and counterbalanced manner. To ensure balanced exposure, they were assigned to one of three groups (n = 4 per group), each following a distinct condition order based on a Latin square design. This approach guaranteed that each session occurred equally across time points (sessions 1-3) and that the order minimized sequence effects by rotating the position of each condition relative to the others. To control for potential carryover-particularly from elevated neurochemical responses following intense exercise (BDNF increases had been reported)-no two high-intensity sessions were scheduled consecutively. Where possible, higher- and lower-intensity protocols were alternated. Furthermore, a seven-day interval separated each session to reduce residual physiological or cognitive effects. The trial protocol was developed in line with CONSORT and SPIRIT guidelines, including relevant extensions for within-subject designs and non-pharmacological interventions. Participants were blinded to the study hypothesis. All exercise sessions were conducted in the morning (09:00-11:00) on a track and field pitch under the supervision of a certified strength and conditioning coach to ensure consistency and adherence to protocol. Participants were instructed to avoid strenuous activity for 48 hours prior, abstain from alcohol and caffeine for 24 hours, and obtain at least 7-8 hours of sleep before each session. Dietary habits and general lifestyle were kept unchanged throughout the study. During the fir