Glycaemic index, glycaemic load and exercise performance.

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The below may be of interest:

Glycaemic index, glycaemic load and exercise performance.Sports Med.

2010;40(1):27-39. doi: 10.2165/11319660-000000000-00000.

O'Reilly J, Wong SH, Chen Y.

The concept of the glycaemic index (GI) was first introduced in the early 1980s

as a method of functionally ranking carbohydrate foods based on their actual

postprandial blood glucose response compared with a reference food (either

glucose or white bread). Although the GI is a debatable topic among many

exercise and health professionals, nutritional recommendations to improve

exercise performance and enhance exercise capacity are regularly based on

information related to the GI. Studies focusing on the consumption of a

pre-exercise GI meal have provided evidence that a benefit exists in relation to

endurance performance and substrate utilization when a low GI meal is compared

with a high GI meal. However, other investigations have shown that when

nutritional strategies incorporating GI are applied to multiple meals, there is

no clear advantage to the athlete in terms of exercise performance and capacity.

It has been suggested that carbohydrate ingestion during endurance exercise

negates the effect of the consumption of pre-exercise GI meals. The glycaemic

load (GL) is a relatively novel concept in the area of sports nutrition, and has

not been widely investigated. Its premise is that the effect, if any, on

exercise performance is determined by the overall glycaemic effect of a diet and

not by the amount of carbohydrate alone.

The claims for GL have been disputed by a number of sports nutrition

specialists, and have gone largely unrecognized by professional and scientific

bodies. Research on the effect of the GL on exercise performance and capacity is

still at an early stage, but recent studies have shown that the concept may have

some merit as far as sports nutrition is concerned. It has been suggested that

the GL may be a better predictor of glycaemic responses than the GI alone.

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Carruthers

Wakefield, UK