Bauer, R. S., Hatfield, B., Haufler, A., Lockwood, P., & Hung, T. (1997). Effect of exercise-induced hypoglycemia on CNS activation in elite cyclists. Medicine and Science in Sports and Exercise, 29(5), Supplement abstract 1275.

The effects of glycogen levels on neural functioning in elite cyclists (N = 6) were evaluated under two conditions: hyperglycemia as induced by carbohydrate feedings and placebo.

It was found that as glycogen levels were eroded, greater neural deactivation occurred. This showed that not only are energy resources for exercise removed with fatigue and lowered glycogen levels, but so are the resources for neural functioning, causing less-efficient and less powerful neural activation.

Implication. Carbohydrate loading has two important effects. First, it extends the fuel supply for endurance exercise allowing individuals to sustain effort levels for longer periods. Secondly, it extends the time the central and peripheral neural systems can maintain their highest levels of activation. As fatigue due to energy supply depletion is incurred it becomes increasingly difficult to produce a maximum intensity movement.

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