PROTEIN-REQUIREMENTS AND MUSCLE MASS STRENGTH CHANGES DURING INTENSIVE TRAINING IN NOVICE BODYBUILDERS

This randomized double-blind cross-over study assessed protein (PRO) requirements during the early stages of intensive bodybuilding training and determined whether supplemental PRO intake (PRO(IN)) enhanced muscle mass/strength gains. Twelve men [22.4 +/- 2.4 (SD) yr] received an isoenergetic PRO (total PRO(IN) 2.62 g . kg-1 . day-1) or carbohydrate (CHO; total PRO(IN) 1.35 g . kg-1 . day-1) supplement for 1 mo each during intensive (1.5 h/day, 6 days/wk) weight training. On the basis of 3-day nitrogen balance (NBAL) measurements after 3.5 wk on each treatment (8.9 +/- 4.2 and -3.4 +/- 1.9 g N/day, respectively), the PRO(IN) necessary for zero NBAL (requirement) was 1.4-1.5 g . kg-1 . day-1. The recommended intake (requirement + 2 SD) was 1.6-1.7 g . kg-1 . day-1. However, strength (voluntary and electrically evoked) and muscle mass [density, creatinine excretion, muscle area (computer axial tomography scan), and biceps N content] gains were not different between diet treatments. These data indicate that, during the early stages of intensive bodybuilding training, PRO needs are approximately 100% greater than current recommendations but that PRO(IN) increases from 1.35 to 2.62 g . kg-1. day-1 do not enhance muscle mass/strength gains, at least during the 1st mo of training. Whether differential gains would occur with longer training remains to be determined.