Efeitos da suplementação intranasal de ocitocina nos indicadores hemodinâmicos e autonômicos pós-exercício em atletas de powerlifting paralímpico

Abstract

The present study aimed to analyze the effects of intranasal administration of 24 IU of oxytocin on post-exercise hemodynamic and autonomic indicators in Paralympic powerlifting athletes. A randomized, double-blind, crossover design was adopted, including fourteen male athletes who underwent two experimental conditions: intranasal oxytocin and placebo. The experimental protocol consisted of a resistance training session in the bench press exercise, comprising five sets of five repetitions at 80% of one-repetition maximum (1RM). Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR), rate-pressure product (RPP), and myocardial oxygen consumption (MVO₂) were assessed at baseline, immediately post-exercise, at 5, 10, 20, 30, 40, 50, and 60 minutes, and at 24 and 48 hours after the session. Statistical analyses included two-way repeated-measures ANOVA followed by Bonferroni post hoc test (p<0.05), with effect size calculated using partial eta squared (η²p). A significant reduction in SBP was observed in the oxytocin condition between 10 minutes (132±4.24 mmHg; 95% CI: 119–154) and 30 minutes (123±4.24 mmHg; 95% CI: 105–142; p=0.049), as well as at 50 minutes (119.5±4.94 mmHg; 95% CI: 102–151; p=0.01; η²p=0.107). A significant between-group difference was detected at 50 minutes, with lower SBP values in the oxytocin condition compared to placebo (119.5±4.94 vs. 132.5±14.84 mmHg; p=0.023; η²p=0.88). DBP showed significant between-condition differences at baseline (87±20.5 vs. 67.5±7.77 mmHg; p=0.013) and immediately post-exercise (69±14.84 vs. 60.5±13.43 mmHg; p=0.009), with a moderate effect size (η²p=0.24). MAP was significantly lower in the oxytocin condition at baseline (92.02±3.3 vs. 105.4±0.9 mmHg; p=0.038) and immediately after exercise (86.5±15.3 vs. 103.5±8.0 mmHg; p=0.020; η²p=0.137). Significant reductions in RPP were identified between 10 and 50 minutes (9841 vs. 8598 mmHg·bpm) and between 10 and 60 minutes (8526 mmHg·bpm) in the oxytocin condition. MVO₂ increased immediately after exercise, followed by a significant reduction between 10 and 50 minutes (p≤0.001; η²p up to 0.468). Regarding heart rate variability (HRV), the variables IntRR, SDNN, and RMSSD were analyzed at baseline, immediately postexercise, and at 24 and 48 hours post-exercise. Significant alterations in HRV indices were observed immediately after training in both conditions, indicating acute autonomic reorganization. The intranasal administration of 24 IU of oxytocin combined with exercise influenced acute autonomic modulation in Paralympic powerlifting athletes, with observable effects on HRV indices. However, late-phase responses appeared to be predominantly associated with the physiological load of training. These findings contribute to the understanding of the neuroendocrine effects of oxytocin on autonomic and hemodynamic control in high-performance athletes with disabilities, expanding knowledge regarding physiological monitoring strategies in this population.