Brown, Laura, Midgley, Adrian W., Vince, Rebecca V., Madden, Leigh A. and McNaughton, Lars R. (2013) High versus low glycemic index 3-h recovery diets following glycogen-depleting exercise has no effect on subsequent 5-km cycling time trial performance. Journal of Science and Medicine in Sport, 16 (5). pp. 450-454.

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Abstract

OBJECTIVES:

Some athletes train/compete multiple times in a single day and rapid restoration of muscle and hepatic glycogen stores is therefore important for athletic performance.

DESIGN:

Randomised, counterbalanced, crossover, single blinded study investigated the effects of low/high glycaemic index (GI) meals on the physiological responses to a 3-h recovery period and subsequent 5-km cycling time trial (TT).

METHODS:

Seven male cyclists completed glycogen-depleting exercise followed by a 3-h recovery period, when participants consumed either a high or low GI meal providing 2gkg(-1) BM of carbohydrate. Participants then performed a 5-km cycling TT. Blood samples were analysed for glucose insulin, free fatty acid (FFA) and triglyceride.

RESULTS:

There was no significant difference between the median (IQR) cycling TT time of 8.5 (3.0) min in the LGI condition and 8.4 (1.8) min in the HGI condition (p=0.45). Serum insulin was significantly higher in the HGI condition throughout the 3-h recovery period (p=0.025), FFA concentrations were higher in the HGI condition only at 30min into recovery (p=0.008). The respiratory exchange ratio (p=0.028) and carbohydrate oxidation rate (p=0.015) increased over time in the HGI condition, whereas the rate of fat oxidation demonstrated the opposite response (p=0.001). No significant differences between conditions were observed for any physiological variables at the end of the 5-km TT.

CONCLUSIONS:

Although the GI of the two meals indicated important metabolic differences during the recovery period, there was no evidence suggesting these differences influenced subsequent 5-km TT performance.

Item Type:	Article
Status:	Published
DOI:	https://doi.org/10.1016/j.jsams.2012.10.006
Subjects:	R Medicine > RC Internal medicine > RC1200 Sports Medicine
School/Department:	School of Science, Technology and Health
URI:	https://ray.yorksj.ac.uk/id/eprint/513

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