ABSTRACT
BACKGROUND: Creatine (Cr) supplementation has been widely used among athletes and physically active individuals. Secondary to its performance-enhancing ability, an increase in oxidative stress may occur, thus prompting concern about its use. The purpose of this study is to investigate the effects of Cr monohydrate supplementation and resistance training on muscle strength and oxidative stress profile in healthy athletes. METHODS: A randomized, double-blind, placebo-controlled method was used to assess twenty-six male elite Brazilian handball players divided into 3 groups: Cr monohydrate supplemented group (GC, N = 9), placebo group (GP, N = 9), no treatment group (COT, N = 8) for 32 days. All subjects underwent a resistance training program. Blood samples were drawn on 0 and 32 days post Cr supplementation to analyze the oxidative stress markers, thiobarbituric acid reactive species (TBARS), total antioxidant status (TAS), and uric acid. Creatine phosphokinase, urea, and creatinine were also analyzed, as well. Fitness tests (1 repetition maximum - 1RM and muscle endurance) were performed on the bench press. Body weight and height, body fat percentage (by measuring skin folds) and upper muscular area were also evaluated. Statistical analysis was performed using ANOVA. RESULTS: Only GC group showed increase in 1RM (54 ± 9 vs. 63 ± 10 kg; p = 0.0356) and uric acid (4.6 ± 1.0 vs. 7.4 ± 1.6 mg/dl; p = 0.025), with a decrease in TAS (1.11 ± 0.34 vs. 0.60 ± 0.19 mmol/l; p = 0.001). No differences (pre- vs. post-training) in TBARS, creatine phosphokinase, urea, creatinine, body weight and height, body fat percentage, or upper muscular area were observed in any group. When compared to COT, GC group showed greater decrease in TAS (-0.51 ± 0.36 vs. -0.02 ± 0.50 mmol/l; p = 0.0268), higher increase in 1RM (8.30 ± 2.26 vs. 5.29 ± 2.36 kg; p = 0.0209) and uric acid (2.77 ± 1.70 vs. 1.00 ± 1.03 mg/dl; p = 0.0276). CONCLUSION: We conclude that Cr monohydrate supplementation associated with a specific resistance program promoted a meaningful increase in muscle strength without inducing changes in body composition. The observed significant increase in uric acid and the decrease in TAS suggest that creatine supplementation, despite promoting acute effects on muscle strength improvement, might induce oxidative stress and decreases total antioxidant status of subjects.
ABSTRACT
O objetivo deste estudo foi verificar a associação entre o nível de aptidão física e lesões desportivas (LD). Foram investigados 162 atletas, integrantes das equipes de representação da cidade de Sorocaba/SP. Tratou-se de estudo transversal, configurando-se como variável independente a aptidão física e como dependente as LD procedeu-se à análise de contingência, considerando LD como efeito e percentual de gordura corporal,resistência muscular abdominal e de membros superiores (MMSS), flexibilidade e característica da modalidade (individual ou coletiva) como exposição, de sorte que Odds Ratio (OR) e respectivos Intervalos de Confiança (IC) foram calculados por relação de distribuição diferencial. Os principais resultados revelaram ausência de associação entre LD e sexo, neste sentido: i) atletas com percentual e gordura acima da média referencial, apresentaram OR igual 2,24 de LD; ii) atletas com baixa flexibilidade apresentaram OR igual 2,36 de LD; iii) atletas com resistência muscular de MMSS reduzida revelaram OR = 2,35 de LD e iv) praticantes de modalidades coletivas mostraram risco 4,23 maior de LD do que os atletas de modalidades individuais. A partir destes resultados pode-se concluir que,independentemente do sexo, os atletas com gordura corporal elevada, baixa flexibilidade, resistência muscular de MMSS reduzida e que praticam modalidades coletivas, apresentaram risco aumentado de se lesionarem
