Obesity appears to be associated with altered muscle protein synthetic and breakdown responses to increased nutrient delivery in older men, but not reduced muscle mass or contractile function.

Murton, Andrew J.; Marimuthu, Kanagaraj; Mallinson, Joanne E.; Selby, Anna L.; Smith, Kenneth; Rennie, Michael J.; Greenhaff, Paul L.

Abstract

Obesity is increasing, yet despite the necessity to maintain muscle mass and function with age, the effect of obesity on muscle protein turnover in older adults remains unknown. Eleven obese (BMI 31.9 ±1.1) and 15 healthy weight (HW; BMI 23.4 ±0.3) older men (55-75 years old) participated in a study that determined muscle protein synthesis (MPS) and leg protein breakdown (LPB) under post-absorptive (hypoinsulinaemic euglycaemic clamp) and post-prandial (hyperinsulinemic hyperaminoacidaemic euglycaemic clamp) conditions. Obesity was associated with systemic inflammation, greater leg fat mass, and patterns of mRNA expression consistent with muscle deconditioning, whilst leg lean mass, strength and work done during maximal exercise were no different. Under post-absorptive conditions, MPS and LPB were equivalent between groups, while insulin and amino acid administration increased MPS in only HW subjects and was associated with lower leg glucose disposal (LGD, 63%) in obese. Blunting of MPS in the obese was offset by an apparent decline in LPB, which was absent in HW subjects. Lower post-prandial LGD in obese subjects and blunting of MPS responses to amino acids suggests obesity in older adults is associated with diminished muscle metabolic quality. However this doesn’t appear to be associated with lower leg lean mass or strength.

Citation

Murton, A. J., Marimuthu, K., Mallinson, J. E., Selby, A. L., Smith, K., Rennie, M. J., & Greenhaff, P. L. (2015). Obesity appears to be associated with altered muscle protein synthetic and breakdown responses to increased nutrient delivery in older men, but not reduced muscle mass or contractile function. Diabetes, 64(9), https://doi.org/10.2337/db15-0021

• Journal Article Type: Article
• Publication Date: Sep 1, 2015
• Deposit Date: Feb 18, 2016
• Publicly Available Date: Feb 18, 2016
• Journal: Diabetes
• Print ISSN: 0012-1797
• Electronic ISSN: 1939-327X
• Publisher: American Diabetes Association
• Peer Reviewed: Peer Reviewed
• Volume: 64
• Issue: 9
• DOI: https://doi.org/10.2337/db15-0021
• Keywords: Muscle, Obesity, Ageing
• Public URL: https://nottingham-repository.worktribe.com/output/758072
• Publisher URL: http://diabetes.diabetesjournals.org/content/64/9/3160
• Additional Information: This is an author-created, uncopyedited electronic version of an article accepted for publication in Diabetes. The American Diabetes Association (ADA), publisher of Diabetes, is not responsible for any errors or omissions in this version of the manuscript or any version derived from it by third parties. The definitive publisher-authenticated version is available online at http://diabetes.diabetesjournals.org/content/64/9/3160http://diabetes.diabetesjournals.org.