Effects of the glycemic index of breakfast on metabolic responses to brisk walking in females

doi:doi:10.1038/sj.ejcn.1602566

European Journal of Clinical Nutrition (2007) 61, 590–596. doi:10.1038/sj.ejcn.1602566; published online 29 November 2006

Effects of the glycemic index of breakfast on metabolic responses to brisk walking in females

Contributors: SHB was involved in all parts of the study from conception to preparation of the final manuscript. CW was involved in the project design, discussion and interpretation of results and manuscript preparation. ES was involved in data analysis, discussion and interpretation of results and manuscript preparation. MN was involved in the experimental aspects of the study and sample collection, analysis and interpretation.

S H Backhouse¹, C Williams², E Stevenson³ and M Nute²

¹Carnegie Research Institute, Leeds Metropolitan University, Leeds, UK
²School of Sport and Exercise Sciences, Loughborough University, Loughborough, UK
³School of Psychology and Sports Sciences, Northumbria University, Newcastle Upon Tyne, UK

Correspondence: Dr SH Backhouse, Carnegie Research Institute, Leeds Metropolitan University, Fairfax Hall, Headingley Campus, Leeds LS6 3QS, UK. E-mail: S.Backhouse@leedsmet.ac.uk

Received 28 April 2006; Revised 12 October 2006; Accepted 17 October 2006; Published online 29 November 2006.

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Abstract

Objective:

The aim of this study was to examine the metabolic responses during 1 h of brisk walking, 3 h after ingesting high glycemic index (HGI) and moderate glycemic index (MGI) breakfasts.

Design and subjects:

Six females completed three treadmill walking trials ( $approx$ 50% Vdot O₂ max), separated by at least 1 month. Three hours before walking, they ingested either water or a HGI or MGI breakfast. The MGI breakfast consisted of a mixture of an HGI breakfast cereal and low GI carbohydrate (CHO) foods. The GI values of the HGI and MGI meals were 77 and 51, respectively.

Setting:

The study took place in the School of Sport and Exercise Sciences at Loughborough University, Loughborough, UK.

Results:

In the HGI and MGI trials, plasma glucose and serum insulin concentrations peaked 15 min into the postprandial period. At the onset of exercise, plasma insulin concentrations were twofold higher in the HGI (31.5 plusminus 7.7 l U l^-1) than in the MGI trial (15.21.9 l U l^-1) (P<0.05). However, there were no differences in substrate utilization between the two CHO trials.

Conclusion:

These results suggest that although the addition of LGI CHO foods to an HGI breakfast cereal reduces the overall GI of the meal, the metabolic response to exercise is similar to that following a breakfast comprised entirely of HGI foods.

Keywords:

pre-exercise meal, CHO, glycemic index, walking, women

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Original Article