Brown, Laura, Midgley, Adrian, Thomas, Gemma, Thurlow, Shane and McNaughton, Lars R. (2009) The effects of low and high glycemic index meals on time trial performance. International journal of sports physiology and performance., 4 (3). p. 331.

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Abstract

The aim of this work was to determine whether the consumption of preexercise
high– or low–glycemic index (GI) meals has a beneficial effect on time trial
performance. Methods: Eight male cyclists were provided with either a high-GI or
low-GI meal, providing 1 g·kg−1 body mass of carbohydrate, 45 min before performing
a 40-km time trial on a Velotron cyclePro. Results: Time trial performance was
significantly improved in the low-GI trial (92.5 ± 5.2 min) compared with the high-GI
trial (95.6 ± 6.0 min) (P = .009). Blood glucose concentrations at the point of exhaustion
were significantly higher in the low-GI trial (5.2± 0.6 mmol·L−1) compared with
the high-GI trial (4.7 ± 0.7 mmol·L−1) (P = .001). There was no significant difference
in estimated carbohydrate oxidation data between the low-GI (2.51 ± 1.74 g·min−1)
and high-GI (2.18 ± 1.53 g·min−1) meals (P = .195). No significant difference in estimated
fat oxidation was observed between the low-GI (0.15 ± 0.15 g·min−1) and
high-GI (0.29 ± 0.18 g·min−1) diets (P = .83). Conclusions: The improvement in time
trial performance for the low-GI trial may be associated with an increased availability
of glucose to the working muscles, contributing additional carbohydrate for oxidation
and possibly sparing limited muscle and liver glycogen stores.

Item Type:	Article
Status:	Published
Subjects:	G Geography. Anthropology. Recreation > GV Recreation Leisure Q Science > QP Physiology
School/Department:	School of Science, Technology and Health
URI:	https://ray.yorksj.ac.uk/id/eprint/375

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