Efeito da suplementação de cafeína e ácido cafeico nas adaptações do músculo esquelético induzidas por treinamento

• Autor(a) principal: Caldas, Leonardo Carvalho
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/7185
• topic: Caffeine; Hypertrophy; Muscles; Training; Caffeic acid; Ácido cafeico; Cafeína; Hipertrofia; Músculos - Treinamento; Educação Física; 796

In vivo and in vitro studies have been demonstrating that two of the main metabolites present in coffee - caffeine and caffeic acid - can modulate mTOR pathway activity, which is considered the key pathway in overload-induced skeletal muscle hypertrophy. However, the effect of these substances on skeletal muscle adaptations induced by resistance training remains unknown. OBJECTIVE: To evaluate the effect of chronic administration of caffeine, caffeic acid and their combination of both on skeletal muscle adaptations induced by resistance training. MATERIALS AND METHODS: Fifty male Wistar rats were divided into 5 groups: 1) Sedentary (S); 2) Trained (T); 3) Trained + caffeine (TC); 4) Trained + caffeic acid (TAc); 5) Trained + caffeine plus caffeic acid (TCAc). The groups performed ladder-climbing training with progressive loads 3 times per week for 10 weeks. Supplementation was given by gavage (30 mg/kg) with two daily doses during the 10 weeks of training. The changes in body weight, food intake, strength performance (load carried, total load, training volume, number of climbs) and muscle mass of the soleus, plantar and long digital extensor muscles were evaluated. We also analyzed the cross-sectional area of the muscle fibers using the histology technique by staining with Hematoxylin and Eosin. RESULTS: The study was divided in two moments, first identifying the effect of training protocol (S vs. T) and then identifying the effect of supplementation (T; TC; TAc; TCAc). The training protocol was effective to increase strength in the maximum carried loading test (T: 813 ± 122.8g vs. S: 383 ± 67.0g; p < 0.0001) and in the total loading test (S: 878.0 ± 81.0g vs. T: 1269.8 ± 143.4g; p < 0.0001) after the 10th week of training. In addition, strength gains were observed over time (p < 0.0001). Training protocol also led to reductions in total food intake (T: 245.6 ± 11.6g vs. S: 270.8 ± 26.9g p = 0.0068). No changes were observed in body weight, muscle mass and cross-sectional area of soleus, plantar and EDL (all p ≥ 0.09). When the effect of supplementation was evaluated, no significant differences were found in strength performance, body weight and food intake (all p ≥ 0.13). For changes in muscle mass, when weight of soleus muscle was normalized by final body weight, main effect was found for caffeine (p = 0.01) and difference between T < TCAc groups (p = 0.03). The difference between the groups T < TCAc was also found for the plantar muscle normalized by body weight (p = 0.04), but with main effect for caffeic acid (p 23 = 0.04). However, the analysis of the cross-sectional area of the fibers did not confirm these results (all values of p ≥ 0.19). In addition, no differences in muscle mass were observed when tissue weight was analyzed or normalized by tibia length or dry weight between groups (p values ≥ 0.05). CONCLUSION: The results of the present study demonstrate that the caffeine and/or caffeic acid associated with resistance training did not result in further increases in muscle mass and strength. The resistance training protocol was effective in stimulating greater increases in strength in trained group, but no skeletal muscle hypertrophy was observed, which may is associated with lower food consumption in the trained condition.