Protein Requirements and Muscle mass/strength Changes During Intensive Training in Novice Bodybuilders

J Appl Physiol (1985). 1992 Aug;73(2):767-75. doi: 10.1152/jappl.1992.73.2.767.

Abstract

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.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Body Weight / physiology
  • Diet
  • Dietary Proteins / pharmacology*
  • Double-Blind Method
  • Energy Metabolism
  • Humans
  • Male
  • Muscles / anatomy & histology
  • Muscles / innervation
  • Muscles / physiology*
  • Nitrogen / metabolism
  • Nutritional Requirements*
  • Organ Size / physiology
  • Tomography, X-Ray Computed
  • Weight Lifting*

Substances

  • Dietary Proteins
  • Nitrogen