Effect of diet on performance during recovery from intermittent sprint exercise

Eighteen games players (9 males, 9 females) performed 30 maximum 6-s sprints on a non-motorized treadmill. Each sprint was preceded by a 60-s jog at 40% maximum speed and was followed by a 54-s walk at 20% maximum speed. Thus, the entire test was of 60-min duration. The subjects were then randomly assigned to three groups and repeated the 1-h test 24 h later after consuming either a high, normal or low carbohydrate diet (79 +/- 3, 47 + 8, 12+1% CHO, respectively). During trial 1, mean power output declined from 653 + 131 to 600+ 158 W during the 30 sprints (P0.01) and power output was lower during trial 2 than during trial 1 (n = 18, P 0.01). During trial 2, there were no differences in sprint performance between the dietary groups for the exercise test as a whole (trial 2 mean power lower than trial 1 by 0.2, 0.5 and 5.0% for the high, normal and low CHO groups, respectively; N.S.#CP, but if only the first nine sprints are considered, then the high CHO group performed better than the low CHO group (P0.05). Blood lactate and glucose concentrations were lower during trial 2 than trial 1 by 4.5, 13.8 and 29.0% (lactate)and 14.9, 11.3 and 35.8% (glucose) for the high, normal and low CHO groups, respectively (both P0.01). Thus, both the metabolic responses to, and the performance of, maximum intermittent exercise were reduced when the test was repeated after 24 h recovery. In addition, both the performance and the metabolic responses to test 2 were altered by dietary manipulation in the intervening period.