Abstract
Exercise serves as a potent physiological stimulus influencing brain-derived neurotrophic factor (BDNF), a key molecule involved in neuronal maintenance, synaptic plasticity, and cognitive regulation. However, the temporal dynamics of circulating BDNF in response to varying exercise intensities remain poorly understood. This study investigated serum BDNF kinetics following low- and moderate-intensity continuous exercise (LICE, MICE) and high-intensity interval exercise (HIIE) in young healthy men. Twelve participants completed all three exercise sessions in a randomized crossover design with seven-day washouts. Venous blood samples were collected at baseline, immediately post-exercise, and at 5, 15, 30, 45, and 60 min of recovery. Serum BDNF and blood lactate concentrations were measured, and heart rate was monitored continuously during each exercise session. BDNF levels were significantly higher in HIIE than in both LICE and MICE across all time points (p < 0.001), with no differences between LICE and MICE (p > 0.05). Within-group analysis revealed that HIIE induced a pronounced but transient rise in BDNF, peaking at 15 min post-exercise and returning to baseline by 60 min. These results suggest that HIIE elicits a distinct neurotrophic response pattern shaped by exercise intensity and interval structure. Our findings provide descriptive data on serum BDNF kinetics that may inform future mechanistic research. Trial registration: The study was registered on ClinicalTrials.gov (identifier: NCT07175831 https://clinicaltrials.gov/study/NCT07175831 ) on 15th of September 2025.