1. Plasma concentrations of gastrin, glucose, vasoactive intestinal polypeptide and non-esterified fatty acid were analysed in six male endurance runners and six male hockey players before, during and 15 min after 90 min treadmill running at 65% maximum oxygen uptake under two conditions: no fluid ingestion (trial A) and ingestion of 8% maltodextrin solution (trial B).

2. Exercise resulted in significantly elevated plasma gastrin concentrations compared with resting values in both groups after trial A (endurance runners, 69.4 ng/l; hockey players 71.4 ng/l) and trial B (endurance runners, 105.5 ng/l; hockey players, 83.2 ng/l). The gastrin response was not significantly different between the trials.

3. Plasma vasoactive intestinal polypeptide levels increased significantly beyond resting levels for both groups during trial A (endurance runners, 76.1 ± 53.7 ng/l; hockey players 155.6 ± 41.9 ng/l) and trial B (endurance runners 47.5 ± 21.3 ng/l; hockey players 132.9 ± 43.9 ng/l). The vasoactive intestinal polypeptide response to trial B was significantly attenuated compared with trial A.

4. There were no significant differences between endurance runners and hockey players for plasma gastrin, although hockey players produced significantly elevated concentrations of plasma vasoactive intestinal polypeptide after both trials compared with endurance runners.

5. Plasma glucose levels throughout trial B were significantly greater than after trial A irrespective of the group. Plasma glucose concentrations were not significantly different between endurance runners and hockey players.

6. Plasma non-esterified fatty acid concentrations rose significantly for both groups throughout exercise. Trial B resulted in an attenuated non-esterified fatty acid response compared with trial A.

7. No significant relationships were identifed between metabolite and gastrointestinal hormone concentrations, or between maximum oxygen uptake and the hormonal response to exercise.

8. These results highlight the attenuating role of carbohydrate fluid ingestion and level of aerobic fitness in the responses of plasma vasoactive intestinal polypeptide during prolonged exercise, whereas plasma gastrin is not significantly affected by either.

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