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Gazzetta Medica Italiana Archivio per le Scienze Mediche 2011 June;170(3):177-84


language: English

Blood glucose changes before and during exercise with three meal conditions

Altoé J. L. 1, Pires Da Silva R. 1, Ferreira F. G. 1, Fabrício Cardozo Makkai L. 1, Dos Santos Amorim P. R. 1, Volpe S. 2, Bouzas Marins J. C. 1

1 Department of Physical Education, Federal University of Viçosa, Viçosa, Minas Gerais, Brazil 2 School of Nursing, University of Pennsylvania, Philadelphia, PA, USA


Aim. Carbohydrate (CHO) ingestion maintains blood glucose concentrations during exercise, whereas, pre-exercise meals is important for avoiding hypoglycemic symptoms and delay the onset of fatigue. Our purpose was to evaluate the glycemic response before and during running exercise performed after consuming three types of “breakfast”: mixed meal (BF1); 400 mL CHO drink (BF2); and no previous meal (BF0).
Methods. Fifteen healthy men (age 23.4 years) completed three trials in a randomized counterbalanced order. One-hour after consuming one of the meals, the participants ran at a steady-state on a laboratory treadmill during 60 min in a comfortable environmental condition at an intensity of 80% of their previously determined VO2max. Plasma glucose concentrations were measured at rest, right before consumption of one of the meals, and each 15 min thereafter for one hour as were during exercise (15, 30, 45 and 60 min). Lactate concentration, heart rate (HR), blood pressure (BP) and rating of perceived exertion (RPE) were also evaluated.
Results. Postprandial blood glucose concentrations increased significantly more in BF1 than in BF2. At 15-min during exercise, it was more elevated in BF0 than in BF1. The pre-exercise blood lactate concentration was significantly higher in BF1 and BF2 than in BF0. No substantial effect of the meals was observed in HR, RPE or BP.
Conclusion. The data show that a one-hour run performed by healthy and trained men after an overnight fast does not imply a risk of hypoglycemia and the both preexercise meals are equally effective in maintaining plasma glucose concentrations within normal ranges.

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