Fritzche, R. G., Switzer, T. W., Hodgkinson, B. J., Lee, S. H., Martin, J. C., & Coyle, E. F. (1998). Carbohydrate added to water is better at maintaining maximal power during prolonged exercise. Medicine and Science in Sports and Exercise, 30(5), Supplement abstract 22.

The effects and interaction of water and carbohydrate (CHO) ingestion on prolonged cycling and maximal power (Pmax) were investigated. Endurance-trained heat-acclimatized cyclists (N = 8) exercise for 122 minutes (63% VO2max, 35 degrees Celsius, 50% RH). Pmax was measured for 10 minutes starting at the 22nd minute. This was repeated every 30 minutes to produce five observations. Immediately before and during exercise Ss received the following:

  1. Approximately 3.5 liters of water with no CHO.
  2. Approximately 3.5 liters of water with approximately 220 grams of CHO (a 6% solution).
  3. Approximately 220 grams of CHO in .4 liters of water (40% solution).
  4. A placebo of .4 liters of water with no CHO.

All treatments were similar at 22 minutes but then changes occurred depending upon the substances ingested.

  1. Ingestion of CHO alone did not slow the decline (-14%) in Pmax any more than a placebo.
  2. Water alone slowed the decline in power (-10%) throughout the task.
  3. Ingestion of a large amount of water and carbohydrate slowed the decline even further (-7%).

Implication. A 6% CHO solution is the best supplement to ingest during prolonged exercise.

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