Nethery, V., Nelson-Pfab, C., Bergman, E., & Gee, D. (1997). Pre-exercise consumption of commercial energy bars affects plasma glucose regulation during prolonged intense cycling. Medicine and Science in Sports and Exercise, 29(5), Supplement abstract 1422.

The effects of several commercially available energy bars on a 60 km time trial (indoor trainer) and physiological factors were assessed. The energy supplements were:

• 76% CHO, 15% protein, 8% fat (HC);
• 40% CHO, 30% protein, 30% fat (MOD);
• 30% CHO, 8% protein, 58% fat (HF); and
• placebo.

Each "meal" was weighted to provide 5 kcals/kg of energy. Diet was controlled for three days prior to each trial. An eight-hour fast preceded ingestion, which occurred one hour before commencement of the trial. Ss (N = 5) were trained cyclists. Plasma glucose, completion time, heart rate, and VO2 data were collected at each 10 km interval.

There were no statistical differences between any condition although performance time was slower and in-performance glucose levels were lower in the HC condition.

Implication. A commercially available high-carbohydrate bar generated a hypoglycemic state but provided no performance benefit in a 60 km time trial. The ingestion of such foods should be evaluated and only used in individuals for whom benefits have been objectively demonstrated.

Return to Table of Contents for this issue.