Pre-Exercise Breakfast Ingestion versus Extended Overnight Fasting Increases Postprandial Glucose Flux after Exercise in Healthy Men: Pre-exercise feeding and postprandial glucose flux

Robert M Edinburgh, Aaron Hengist, Harry A Smith, Rebecca L Travers, Francoise Koumanov, James A Betts, Dylan Thompson, Jean-Philippe Walhin, Gareth A Wallis, D Lee Hamilton, Emma J Stevenson, Kevin D Tipton, Javier T Gonzalez

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Abstract

The aim of this study was to characterize postprandial glucose flux after exercise in the fed versus overnight fasted state and to investigate the potential underlying mechanisms. In a randomized order, twelve men underwent breakfast-rest [(BR) 3 h semirecumbent], breakfast-exercise [(BE) 2 h semirecumbent before 60 min of cycling (50% peak power output)], and overnight fasted exercise [(FE) as per BE omitting breakfast] trials. An oral glucose tolerance test (OGTT) was completed after exercise (after rest on BR). Dual stable isotope tracers ([U- 13C] glucose ingestion and [6,6- 2H 2] glucose infusion) and muscle biopsies were combined to assess postprandial plasma glucose kinetics and intramuscular signaling, respectively. Plasma intestinal fatty acid binding (I-FABP) concentrations were determined as a marker of intestinal damage. Breakfast before exercise increased postexercise plasma glucose disposal rates during the OGTT, from 44 g/120 min in FE {35 to 53 g/120 min [mean (normalized 95% confidence interval)] to 73 g/120 min in BE [55 to 90 g/120 min; P = 0.01]}. This higher plasma glucose disposal rate was, however, offset by increased plasma glucose appearance rates (principally OGTT-derived), resulting in a glycemic response that did not differ between BE and FE (P = 0.11). Plasma I-FABP concentrations during exercise were 264 pg/ml (196 to 332 pg/ml) lower in BE versus FE (P = 0.01). Breakfast before exercise increases postexercise postprandial plasma glucose disposal, which is offset (primarily) by increased appearance rates of orally ingested glucose. Therefore, metabolic responses to fed-state exercise cannot be readily inferred from studies conducted in a fasted state.

Original languageEnglish
Article number00163
Pages (from-to)E1062-E1074
Number of pages13
JournalAmerican Journal of Physiology: Endocrinology and Metabolism
Volume315
Issue number5
Early online date14 Aug 2018
DOIs
Publication statusPublished - 1 Nov 2018

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Keywords

  • Breakfast
  • Exercise
  • Glycemia
  • Insulin sensitivity
  • Metabolism

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Physiology
  • Physiology (medical)

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