Towards optimizing the timing of the pre-exercise meal

Area of Science:

• Sports Science
• Exercise Physiology
• Nutrition Science

Background:

• Pre-exercise nutrition timing significantly impacts athletic performance.
• Understanding optimal meal timing is crucial for athletes to maximize energy availability and endurance.

Purpose of the Study:

• To compare the effects of a 3-hour versus 6-hour prefeeding regimen on exercise performance in active women.
• To determine the influence of meal timing on physiological responses during moderate- to high-intensity exercise.

Main Methods:

• Eight active women completed two treadmill exercise trials, differing in pre-exercise meal consumption time (3 vs. 6 hours).
• Exercise involved moderate-intensity running with intermittent sprints, followed by incremental grade increases to volitional fatigue.
• Physiological markers including time to exhaustion, oxygen uptake, heart rate, perceived exertion, respiratory exchange ratio (RER), blood lactate, glucose, cortisol, and insulin were measured.

Main Results:

• Time to exhaustion was significantly shorter following a 6-hour prefeeding interval compared to a 3-hour interval.
• Lower respiratory exchange ratios (RER) and blood lactate at exhaustion were observed in the 6-hour trials.
• Resting and post-exercise insulin levels were lower in the 6-hour trials, while blood glucose and cortisol responses were similar.

Conclusions:

• Consuming a moderate-high carbohydrate, low-fat, low-protein meal 3 hours before exercise enhances performance in moderate- to high-intensity exercise lasting 35-40 minutes, compared to a 6-hour pre-exercise meal.
• Athletes benefit from strategic meal timing, avoiding prolonged fasting periods before training or competition.