Nutrient Timing for Endurance Athletes

By: Don Gauvreau (courtesy of Inside Fitness)

Nutrient timing is a practice that researchers, athletes and coaches have explored and used for decades now. In simple terms, it's the eating of specific nutrients (usually protein and carbohydrates), in specific amounts and at specific times, such as pre-exercise, during-exercise and post-exercise.

If you’re simply looking to get in shape and maintain a good body composition and healthy lifestyle, then I don’t think nutrient timing is critical to your success. The most important thing is that you consistently eat adequate amounts of healthy foods on a daily basis. If you’re an athlete and looking to improve your performance, however, then employing a nutrient timing strategy is something you’ll definitely want to consider. There’s no doubt strength and power athletes can benefit from nutrient timing strategies, but I believe endurance athletes are the ones who can gain the greatest benefit from proper nutrient timing. With endurance athletes, the effectiveness of nutrient timing is really dependent on optimal fueling of the body. Nutrient timing ensures that endurance athletes, who are burning an excessive amount of energy, are appropriately fueled for optimal performance.

1 to 2 Hours Before Training

Before you head into a big endurance training session or competition it’s important that you consume carbohydrates and some protein or essential amino acids (EAAs). Research shows that when EAAs are consumed before endurance exercise, muscle protein synthesis rates and several signaling proteins related to muscle hypertrophy can be significantly increased. Although protein appears to be beneficial, the priority for an endurance athlete in the time leading up to training should be focused on adequate carbohydrate intake to fully maximize glycogen production in the body. I suggest consuming what I would consider to be a moderate-sized meal, that would be made up of 1 gram of carbohydrates and 0.25 grams of protein per kilogram of bodyweight. So, using an 80-kilogram athlete as an example, that would mean 80 grams of carbohydrates and 20 grams of protein, one to two hours prior to training.

During Training

If your bout of endurance exercise is less than 60 minutes in duration, then I don’t believe there’s a serious need to consume nutrients like protein and carbohydrates during exercise. Research shows that the need for carbohydrate replacement increases in importance as training extends beyond 60 minutes. The need for carbohydrates during shorter durations doesn’t have a lot of scientific backing. Exercise in the 60 to 90-minute range of moderate to high-intensity (65-80% VO2 max) relies heavily on muscle carbohydrate stores. Research shows that replenishing those carbohydrates during exercise beyond 60 minutes facilitates faster recovery and improved performance. In addition, consuming protein or EAAs along with carbohydrates can provide benefits such as muscle glycogen re-synthesis and tissue repair.

4-Hour Window Post-Training

The reason I suggest a 4-hour window after training, and not necessarily something immediately post-training is because if you’re consuming nutrients (protein/EAAs and carbohydrates) before and/or during your training, then there isn’t an immediate need to ingest high amounts of protein and carbs right after training. Research supports this notion too. Many studies show that the intake of high amount of carbs (in the range of 100g per hour) for 4 to 6 hours after exhausting endurance exercise can rapidly stimulate replenishment of muscle glycogen. An easy guideline that I suggest following is to consume 5 grams of carbs per kilogram of body weight within 4 hours after intense training. So, let’s return to our hypothetical 80-kilogram athlete: this person would consume 400 grams of carbs over the course of 4 hours post-exercise. Research shows that adding protein to those carbs increases the rate of glycogen re-synthesis. I suggest consuming 0.25 grams of protein per kilogram of body weight within 4 hours after training. So again, using our 80-kilogram athlete, that would be 80 grams of protein over the course of 4 hours. That protein can help minimize muscle damage and speed up recovery.

Nutrient & Hydration Timing in Hot & Humid Environments

Athletes who are training or competing in the heat have additional nutrient and fluid considerations that need to be accounted for. In the heat, muscles become less efficient and athletes have to work harder. Exercising in heat or humidity places an increased demand on the body and shifts towards anaerobic metabolism, which means an increase in the use of carbohydrates for fuel. Training in the heat also means an increase in sweating and more fluid loss. We already addressed the timing of carbohydrates and protein intake, but the timing of fluid intake to ensure proper hydration is critically important in a hot environment. Your intake of fluids has to be accounted for throughout the entire day for optimal hydration. Here’s a simple plan you can follow:

Immediately Upon Waking

500 mL of water (with a source of electrolytes)

Within 1 Hour Before Training

500 mL of water (with a source of electrolytes)

During Training

150 mL of water (with a source of electrolytes) every 15 minutes (if possible)

Immediately After Training

500 mL of water (with a source of electrolytes)

Throughout the Entire Day

500 mL of water (with a source of electrolytes) every 1-2 hours (or as needed to replace lost fluids)

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