Food Is Fuel
Training breaks the body down. Nutrition builds it back up. For endurance athletes, what you eat directly affects your ability to train consistently, recover adequately, and perform on race day. Yet nutrition remains one of the most neglected aspects of many athletes' preparation. Getting the basics right does not require a degree in biochemistry, just an understanding of a few key principles.
Carbohydrates: The Primary Fuel
During moderate to high-intensity exercise, carbohydrates are your body's preferred energy source. Muscle glycogen stores are limited, typically lasting 60 to 90 minutes of sustained effort before depletion. For endurance athletes, daily carbohydrate intake should match training demands.
- Light training days: 3 to 5 grams per kilogram of body weight
- Moderate training days: 5 to 7 grams per kilogram
- Heavy training or race day: 7 to 12 grams per kilogram
Whole grains, rice, pasta, potatoes, fruits, and oats are excellent sources. Time your largest carbohydrate meals around training sessions for optimal glycogen replenishment.
Protein: Repair and Rebuild
Protein supports muscle repair, immune function, and enzyme production. Endurance athletes should aim for 1.4 to 1.8 grams per kilogram of body weight daily, spread across meals. Consuming 20 to 40 grams of protein within two hours after training maximizes the muscle protein synthesis response.
Lean meats, fish, eggs, dairy, legumes, and tofu are all effective protein sources. The specific source matters less than hitting your daily target consistently.
Fat: The Endurance Reserve
Fat is the dominant fuel source during low-intensity exercise and provides essential fatty acids and fat-soluble vitamins. Endurance athletes should not restrict fat below 20 percent of total calories. Nuts, avocados, olive oil, and fatty fish supply healthy fats that support hormonal function and reduce inflammation.
Hydration Strategy
Dehydration of just 2 percent of body weight impairs endurance performance measurably. Develop a hydration plan based on your sweat rate, which you can estimate by weighing yourself before and after a one-hour training session.
During exercise, aim for 400 to 800 milliliters of fluid per hour, adjusted for conditions and individual sweat rate. For efforts lasting longer than 60 minutes, include electrolytes, particularly sodium, to replace what is lost in sweat.
During-Exercise Fueling
For activities lasting longer than 90 minutes, consuming 30 to 90 grams of carbohydrates per hour maintains blood glucose and delays glycogen depletion. Start fueling early, within the first 30 to 45 minutes, rather than waiting until you feel depleted. Gels, chews, sports drinks, and real food like bananas and rice cakes all work. The best choice is whatever you tolerate well and can consume consistently.
Race Day Nutrition
Never try anything new on race day. Your pre-race meal, during-race fueling, and hydration strategy should all be tested extensively during training. A reliable pre-race meal consumed 2 to 3 hours before the start typically includes 1 to 4 grams of carbohydrate per kilogram with minimal fat and fiber.
Train Your Gut
The gastrointestinal system adapts to during-exercise fueling with practice. Athletes who regularly train with carbohydrate intake during sessions experience fewer stomach issues on race day and can absorb fuel more efficiently. Treat nutrition practice as seriously as any other training session.
Fuel Smarter With Strilab
While Strilab focuses on training load and performance metrics, understanding your fueling needs is essential context for interpreting your data. An underfueled athlete will see declining performance regardless of how well their plan is structured. Pair smart nutrition with Strilab's AI coaching for complete endurance performance optimization.