Background: During competition season, races and games can be scheduled multiple times a week or even within 24 hours. This may interfere with macronutrient periodization, carbohydrate loading regimen, hydration status and nutrition. Most of the studies investigating the influence of diet on performance do not take into consideration that an athlete may need to perform closely spaced, repeated events. The study tested whether the fat-adaptation diet would improve performance on the consecutive day of interval exercise.
Methods: Nine healthy, male amateur athletes were randomly assigned to two diets in a single-blinded, crossover study. The fat-adaptation diet consisted of the first five days high-fat diet (2.62 g/kg/d carbohydrates, 2.23 g/kg/d fat). The day six and seven of the fat-adaptation diet consisted of 5.42 g/kg/d carbohydrates. The balanced carbohydrate diet consisted of a seven-day protocol involving consumption of 5.33 g/kg/d. On day seven of each diet protocol, subjects performed an interval treadmill test dependent on exhaustion. Blood glucose and lactate were measured before and immediately after exercise. The identical treadmill test was performed once again after 24 hours on the day eight of each diet.
Results: There was a significant decrease in the total distance to exhaustion after the fat-adaptation diet (11.2 ±0.6 km vs 10.9 ±0.8 km), p < 0.05 with lactate being lower after exercise on the second day (6.2 ±0.8 mM) compared to the first day (7.4 ±0.9 mM). Glucose was elevated after exercise except on the second test day on the fat-adaptation diet (5.3 ±0.3 mmol/L).
Conclusions: Athletes perform better on the balanced carbohydrate diet than short fat-adaptation diet on the consecutive day of interval test.
Keywords: carbohydrate; exercise performance; fat adaptation; human nutrition; macronutrients.