Impact of combined resistance and aerobic exercise training on branched-chain amino acid turnover, glycine metabolism and insulin sensitivity in overweight humans

Erin L. Glynn, Lucy W. Piner, Kim M. Huffman, Cris A. Slentz, Lorraine Elliot-Penry, Hiba AbouAssi, Phillip J. White, James R. Bain, Michael J. Muehlbauer, Olga R. Ilkayeva, Robert D. Stevens, Kathryn N. Porter Starr, Connie W. Bales, Elena Volpi, M. Julia Brosnan, Jeff K. Trimmer, Timothy P. Rolph, Christopher B. Newgard, William E. Kraus

Research output: Contribution to journalArticlepeer-review

58 Scopus citations

Abstract

Aims/hypotheses: Obesity is associated with decreased insulin sensitivity (IS) and elevated plasma branched-chain amino acids (BCAAs). The purpose of this study was to investigate the relationship between BCAA metabolism and IS in overweight (OW) individuals during exercise intervention. Methods: Whole-body leucine turnover, IS by hyperinsulinaemic–euglycaemic clamp, and circulating and skeletal muscle amino acids, branched-chain α-keto acids and acylcarnitines were measured in ten healthy controls (Control) and nine OW, untrained, insulin-resistant individuals (OW-Untrained). OW-Untrained then underwent a 6 month aerobic and resistance exercise programme and repeated testing (OW-Trained). Results: IS was higher in Control vs OW-Untrained and increased significantly following exercise. IS was lower in OW-Trained vs Control expressed relative to body mass, but was not different from Control when normalised to fat-free mass (FFM). Plasma BCAAs and leucine turnover (relative to FFM) were higher in OW-Untrained vs Control, but did not change on average with exercise. Despite this, within individuals, the decrease in molar sum of circulating BCAAs was the best metabolic predictor of improvement in IS. Circulating glycine levels were higher in Control and OW-Trained vs OW-Untrained, and urinary metabolic profiling suggests that exercise induces more efficient elimination of excess acyl groups derived from BCAA and aromatic amino acid (AA) metabolism via formation of urinary glycine adducts. Conclusions/interpretation: A mechanism involving more efficient elimination of excess acyl groups derived from BCAA and aromatic AA metabolism via glycine conjugation in the liver, rather than increased BCAA disposal through oxidation and turnover, may mediate interactions between exercise, BCAA metabolism and IS. Trial registration:: Clinicaltrials.gov

Original languageEnglish (US)
Pages (from-to)2324-2335
Number of pages12
JournalDiabetologia
Volume58
Issue number10
DOIs
StatePublished - Oct 24 2015

Keywords

  • Branched-chain amino acids
  • Exercise
  • Insulin resistance
  • Metabolomics
  • Obesity
  • Protein

ASJC Scopus subject areas

  • Internal Medicine
  • Endocrinology, Diabetes and Metabolism

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