Impacto da cafeína sobre indicadores neuromusculares, estresse oxidativo e dano muscular no powerlifting paralímpico

Abstract

Introduction: Resistance exercise improves performance but generates fatigue and muscle damage. Caffeine (CA) supplementation is used to mitigate these effects; however, neuromuscular parameters, muscle damage, and oxidative stress still need to be clarified, especially in paralympic powerlifting. Objective: To evaluate the effects of CA supplementation on strength performance (static and dynamic), oxidative stress, and muscle damage in paralympic powerlifting. Methods: This study investigated the acute effects of CA supplementation (9 mg/kg) on indicators of static strength (Rate of Force Development (RFD), Impulse, Peak torque, maximum isometric strength, peak strength at 1 second, and force variability) and dynamic strength (Mean Propulsive Velocity (MPV), Maximum Velocity (Vmax), and Power were evaluated at 45% of 1RM before, after, 24h, and 48h of a training session, and also at 80% of 1RM, performing 5x5). Markers of oxidative stress and enzymatic antioxidant activity (TBARS/MDA, total antioxidant capacity, sulfhydryl groups, and uric acid) and markers of muscle damage (thermography, CK (creatine kinase), LDH (lactate dehydrogenase), and creatinine) were assessed in 14 male Paralympic powerlifting athletes. The protocol included two conditions (CA and PLA (placebo)), 5x5 at 80% of 1RM in the bench press. Results: Regarding static strength, CA significantly increased RFD, impulse, peak torque, and maximum isometric strength, while improving peak strength at 1 second and reducing variability, suggesting enhanced motor unit recruitment. Regarding dynamic strength, no significant differences were observed at 45% of 1RM. However, at 80% of 1RM, the CA group demonstrated significant improvement compared to the PLA group during Set 1 and Set 5. Nonetheless, CA also led to an increase in oxidative stress, as evidenced by elevated TBARS levels, reduced antioxidant capacity, decreased sulfhydryl groups, and higher uric acid concentrations post-exercise. Thermography showed an increase in all evaluated muscles with CA compared to the PLA condition. For CK, LDH, and creatinine, there were no significant differences. Conclusion: CA demonstrates promising ergogenic properties, contributing to increased muscle strength and allowing athletes to maintain training intensity even with higher loads. Furthermore, it does not appear to increase muscle damage, suggesting a safe usage profile in this regard. However, while it acutely improves neuromuscular performance, CA does not reduce—and may even exacerbate—exercise-induced oxidative stress, indicating that its use in strength sports should be approached with caution.