Effect of a Whole-Body HIIT Session on Psychophysiological Responses, Muscle Damage, and Oxidative Stress in Healthy Young Men: A Pilot Study

Introduction: Optimizing exercise prescription requires a comprehensive understanding of exercise-induced muscle damage (EIMD) kinetics. This study investigated the acute and 72 h recovery responses of psychophysiological markers, muscle damage, and oxidative stress following a single calisthenic high-intensity interval training (HIIT-C) session in healthy young men. Methods: Ten physically active healthy young men completed a HIIT-C protocol consisting of a 5 min warm-up followed by four blocks of five 30 s “all-out” bodyweight exercises (jumping jacks, burpees, mountain climbers, and jump squats) interspersed with 30 s passive recovery intervals. Perceptual, cardiovascular, functional, biochemical, oxidative stress, and circulating cell-free DNA (cfDNA) markers were assessed pre-exercise, immediately post-exercise, and at 24, 48, and 72 h post-session. Repeated measures were analyzed using a one-way ANOVA (p < 0.05). Results: The HIIT-C session elicited significant acute increases in heart rate, blood lactate, and perceived exertion (p < 0.001), accompanied by an immediate reduction in perceived recovery. Mood state analysis revealed immediate post-exercise increases in fatigue and decreases in vigor (persisting for 72 h), without alterations in depression and anger. Muscle soreness increased and general well-being decreased up to 48 h post-exercise. Nuclear cfDNA (n-cfDNA) was elevated immediately post-session and returned to baseline within 24 h, whereas mitochondrial cfDNA (mt-cfDNA) remained unchanged. Significant elevations in muscle thickness (biceps brachii, triceps brachii, rectus femoris), serum enzymes (CK, LDH, AST, ALT) and oxidative stress markers (TBARS, AOPP) were observed alongside reductions in the countermovement jump performance and pressure pain threshold. Most markers remained altered at 24 and 48 h; by 72 h post-exercise, all variables returned to baseline values except for the biceps brachii muscle thickness. Conclusions: A single HIIT-C session induces significant psychophysiological perturbations and systemic EIMD requiring a 48 to 72 h recovery period. These findings delineate the post-exercise recovery kinetics of bodyweight HIIT, providing empirical data to assist practitioners in optimizing training periodization and mitigating overtraining risks in young adult men.