Dietary-energy/protein Optimum For N-balance And Muscle Hypertrophy During Two Weeks Of Resistance Training

In a previous paper, dietary-protein needs for better muscle hypertrophy during 2-week resistance training were found to be between 1.5 and 2.5 g/kg/d (Maesta et al. Rev. Bras. Med. Esporte 2008). However, not only total energy adequacy but also energy-yielding nutrients are important. PURPOSE: To determine adequate energy and the energy-yielding nutrient (CHO/Fat) ratio for N-balance and related muscle-mass gain in training body builders. METHODS: forty-two healthy young men (18-35yrs), without exogenous anabolics and at least two years of body-building training were assessed at baseline (MO) for food intake, anthropometry (calculation of body fatness-BF and muscle mass-MM) and urinary nitrogen excretion (for N-balance, NB). The assessment was repeated after four weeks (M1) with a diet of 1.8g prot/kg/d and different proportions of kcal/prot and CHO/Fat along with a unique 6-day/wk resistance-training protocol. Statistics between groups and among moments were performed by ANOVA and Student's t test along with regression analysis (Pearson) with p=0.05. RESULTS: Total energy intake correlated positively with NB (r=0.69), BW (r=0.59), MM (r=0.41) and BF (r=0.34), with ≥ 30kcal/g protein giving greater gain of both MM and NB (than < 30kcal/g prot) without BF gain. Dietary CHO showed a strong positive relationship and dietary-fat a negative relationship with NB and MM. Dietary CHO/Fat (calorie) ratio > 6 resulted in better MM gain (2.2kg) and BF loss (-1.1%) for the same BW. CONCLUSION: For the best MM gain and NB during a short period of resistance training, the recommended diet would provide ∼ 1.8g prot/kg/d, ≥ 30kcal/g/prot in a proportion of CHO/Fat calories ≥ 6. Supported by Fapesp and CNPq