Aging Is Accompanied by a Blunted Muscle Protein Synthetic Response to Protein Ingestion

PLoS One. 2015 Nov 4;10(11):e0140903. doi: 10.1371/journal.pone.0140903. eCollection 2015.


Purpose: Progressive loss of skeletal muscle mass with aging (sarcopenia) forms a global health concern. It has been suggested that an impaired capacity to increase muscle protein synthesis rates in response to protein intake is a key contributor to sarcopenia. We assessed whether differences in post-absorptive and/or post-prandial muscle protein synthesis rates exist between large cohorts of healthy young and older men.

Procedures: We performed a cross-sectional, retrospective study comparing in vivo post-absorptive muscle protein synthesis rates determined with stable isotope methodologies between 34 healthy young (22±1 y) and 72 older (75±1 y) men, and post-prandial muscle protein synthesis rates between 35 healthy young (22±1 y) and 40 older (74±1 y) men.

Findings: Post-absorptive muscle protein synthesis rates did not differ significantly between the young and older group. Post-prandial muscle protein synthesis rates were 16% lower in the older subjects when compared with the young. Muscle protein synthesis rates were >3 fold more responsive to dietary protein ingestion in the young. Irrespective of age, there was a strong negative correlation between post-absorptive muscle protein synthesis rates and the increase in muscle protein synthesis rate following protein ingestion.

Conclusions: Aging is associated with the development of muscle anabolic inflexibility which represents a key physiological mechanism underpinning sarcopenia.

MeSH terms

  • Aged
  • Aging*
  • Cross-Sectional Studies
  • Dietary Proteins / metabolism
  • Humans
  • Male
  • Muscle Proteins / metabolism*
  • Postprandial Period
  • Protein Biosynthesis / physiology*
  • Retrospective Studies
  • Sarcopenia / metabolism
  • Sarcopenia / pathology
  • Young Adult


  • Dietary Proteins
  • Muscle Proteins

Grant support

The authors received no specific funding for this work.