Efeitos da suplementação com creatina monohidrato no curso temporal da força e da hipertrofia muscular no treinamento tradicional e com restrição do fluxo sanguíneo

Abstract

Introduction: Creatine Monohydrate supplementation has been extensively investigated in the scientific literature. The intake of this compound is justified by increases in intramuscular creatine and creatine phosphate (CP) concentrations, which increases ATP resynthesis, mainly during short term-high and high intensity exercises (<30 seconds). This, once repeated in resistance training exercises, would allow for the accumulation of muscle contractile proteins in the exercised muscle (muscle hypertrophy). According to previous studies by our group, BFR training proved to be superior in increasing muscle mass in the short term (<6 weeks), when compared to traditional hypertrophy training (TRAD). However, TRAD training proved to be superior in inducing gains in maximum muscle strength. Considering that creatine supplementation induces important gains in muscle performance, it is possible that such increased performance may also manifest in the BFR method, thus resulting in gains of muscle mass. Objective: To investigate the effects of 8-week creatine monohydrate or placebo supplementation on muscle strength and muscle thickness, employing different training paradigms (BFR vs TRAD). Materials and Methods: 18 healthy male subjects, between 18 and 30 years old, were randomized between the placebo (n = 9) or creatine (n = 9) group. The volunteers of both groups were trained unilaterally in the bicep curl exercise (each arm was allocated to a different training model, TRAD or BFR) for 8 weeks. In the present study, resistance training was performed employing the unilateral resistance training method for both paradigms, TRAD and BFR. Muscle strength was evaluated as follows: 1) Muscle dynamic strength was measured utilizing repetitions to failure, employing different 1 RM percentage (30%, 70% of 1RM); 2) Maximal dynamic strength was evaluated via 1 RM test; 3) Volume of training in each exercise session was calculated using the formula: number of sets x number of repetitions x load, in kilograms. Muscle hypertrophy was determined via muscle thickness measurements using ultrasound equipment and body composition was measured through skinfold caliper measurements. All measures of muscle thickness, circumference, strength, and body composition were evaluated at the moment 0, 2, 4, 6 and 8 weeks. Results: There were additional gains in the muscle thickness variable for both TRAD CR and BFR CR methods (17.85% and 14.35% respectively) when compared to the TRAD PL and BFR PL (9.53% vs 9, 08% respectively) (p = 0.011). Maximum strength (1RM) was increased in the TRAD CR group when compared to the BFR CR (35.89% vs 11.67% respectively) (p = 0.027). Repetition to failure test at 30% of 1RM was increased in the BFR CR group, when compared to TRAD CR (153.15% vs 90.04% respectively) (p = 0.025). Repetition to failure test at 70% 1RM was greater in BFR-CR than in placebo BFR (181.10% vs 79.19% respectively) (p = 0.007). There was an increase in total body weight in the group supplemented with creatine, when compared to the placebo group (2kg vs 0.01kg) (p = 0.002). Conclusion: Our data show that creatine supplementation favored increases in muscle mass in both groups (TRAD and BFR). Creatine was more effective at maximum strength for the TRAD group and repetitions to failure at 30% of 1RM for the BFR group, when compared to the placebo group. As already demonstrated in the literature, creatine supplementation was able to exert anabolic effects in the TRAD training modality. However, this is the first study to demonstrate that creatine supplementation also exerts anabolic and ergogenic effects on BFR training. The observed improvements in muscle performance and muscle hypertrophy, may have important implications not only in our study but also in other scenarios, such as rehabilitation programs or athletic programs, where BFR is also utilized.