Hypoenergetic diet-induced reductions in myofibrillar protein synthesis are restored with resistance training and balanced daily protein ingestion in older men

Am J Physiol Endocrinol Metab. 2015 May 1;308(9):E734-43. doi: 10.1152/ajpendo.00550.2014. Epub 2015 Mar 3.


Strategies to enhance weight loss with a high fat-to-lean ratio in overweight/obese older adults are important since lean loss could exacerbate sarcopenia. We examined how dietary protein distribution affected muscle protein synthesis during energy balance (EB), energy restriction (ER), and energy restriction plus resistance training (ER + RT). A 4-wk ER diet was provided to overweight/obese older men (66 ± 4 yr, 31 ± 5 kg/m(2)) who were randomized to either a balanced (BAL: 25% daily protein/meal × 4) or skewed (SKEW: 7:17:72:4% daily protein/meal; n = 10/group) pattern. Myofibrillar and sarcoplasmic protein fractional synthetic rates (FSR) were measured during a 13-h primed continuous infusion of l-[ring-(13)C6]phenylalanine with BAL and SKEW pattern of protein intake in EB, after 2 wk ER, and after 2 wk ER + RT. Fed-state myofibrillar FSR was lower in ER than EB in both groups (P < 0.001), but was greater in BAL than SKEW (P = 0.014). In ER + RT, fed-state myofibrillar FSR increased above ER in both groups and in BAL was not different from EB (P = 0.903). In SKEW myofibrillar FSR remained lower than EB (P = 0.002) and lower than BAL (P = 0.006). Fed-state sarcoplasmic protein FSR was reduced similarly in ER and ER + RT compared with EB (P < 0.01) in both groups. During ER in overweight/obese older men a BAL consumption of protein stimulated the synthesis of muscle contractile proteins more effectively than traditional, SKEW distribution. Combining RT with a BAL protein distribution "rescued" the lower rates of myofibrillar protein synthesis during moderate ER.

Keywords: aging; energy restriction; stable isotope.

Publication types

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

MeSH terms

  • Aged
  • Aging / metabolism
  • Body Composition / drug effects
  • Caloric Restriction / adverse effects*
  • Diet, Reducing / adverse effects
  • Dietary Proteins / pharmacology*
  • Eating
  • Humans
  • Male
  • Middle Aged
  • Motor Activity / physiology
  • Muscle Proteins / biosynthesis*
  • Muscle Proteins / drug effects
  • Muscular Atrophy / etiology
  • Muscular Atrophy / metabolism
  • Muscular Atrophy / rehabilitation
  • Protein Biosynthesis* / drug effects
  • Resistance Training*


  • Dietary Proteins
  • Muscle Proteins