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 (PROIN) enhanced muscle mass/strength gains. Twelve men [22.4 +/- 2.4 (SD) yr] received an isoenergetic PRO (total PROIN 2.62 g.kg-1.day-1) or carbohydrate (CHO; total PROIN 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 PROIN 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 PROIN 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.
Lemon
P W
PW
School of Biomedical Sciences, Kent State University, Ohio 44242.
Tarnopolsky
M A
MA
MacDougall
J D
JD
Atkinson
S A
SA
D000328:Adult; D001835:Body Weight / Q000502:physiology; D004032:Diet; D004044:Dietary Proteins / Q000494:pharmacology*; D004311:Double-Blind Method; D004734:Energy Metabolism; D006801:Humans; D008297:Male; D009132:Muscles / Q000033:anatomy & histology / Q000294:innervation / Q000502:physiology*; D009584:Nitrogen / Q000378:metabolism; D009751:Nutritional Requirements; D009929:Organ Size / Q000502:physiology; D014057:Tomography, X-Ray Computed; D014891:Weight Lifting
D004044:Dietary Proteins; D009584:Nitrogen