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Effect of high and low glycaemic index recovery diets on intramuscular lipid oxidation during aerobic exercise

Lookup NU author(s): Professor Mike TrenellORCiD



Intramyocellular lipid (IMCL) and plasma NEFA are important skeletal muscle fuel sources. By raising blood insulin concentrations, carbohydrate ingestion inhibits lypolysis and reduces circulating NEFA. We hypothesised that differences in the postprandial glycaemic and insulin response to carbohydrates (i.e. glycaemic index; GI) could alter NEFA availability and IMCL use during subsequent exercise. Endurance-trained individuals (n 7) cycled for 90 min at 70% VO2peak and then consumed either high GI (HGI) or low GI (LGI) meals over the following 12 h. The following day after an overnight fast, the 90 min cycle was repeated. IMCL content of the vastus lateralis was quantified using magnetic resonance spectroscopy before and after exercise. Blood samples were collected at 15 min intervals throughout exercise and analysed for NEFA, glycerol, glucose, insulin, and lactate. Substrate oxidation was calculated from expired air samples. The 90 min cycle resulted in >2-fold greater reduction in IMCL in the HGI trial (3.5 (sem 1.0) mm/kg wet weight) than the LGI trial (1.6 (sem 0.3) mm/kg wet weight, P<0.05). During exercise, NEFA availability was reduced in the HGI trial compared to the LGI trial (area under curve 2.36 (sem 0.14) mEq/l per h v. 3.14 (sem 0.28) mEq/l per h, P< 0.05 respectively). No other differences were significant. The findings suggest that HGI carbohydrates reduce NEFA availability during exercise and increase reliance on IMCL as a substrate source during moderate intensity exercise. © 2007 The Authors.

Publication metadata

Author(s): Trenell MI, Stevenson E, Stockmann K, Brand-Miller J

Publication type: Article

Publication status: Published

Journal: British Journal of Nutrition

Year: 2008

Volume: 99

Issue: 2

Pages: 326-332

Date deposited: 23/03/2011

ISSN (print): 0007-1145

ISSN (electronic): 1475-2662

Publisher: Cambridge University Press


DOI: 10.1017/S0007114507798963

PubMed id: 17697427


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Funder referenceFunder name
MC_G0802536Medical Research Council