Why Intra-Workout Nutrition is Crucial
For workouts lasting over 60-90 minutes, a pre-exercise meal alone is not enough to sustain peak performance. During prolonged or high-intensity efforts, your body depletes its muscle glycogen stores—the primary fuel source for working muscles. Once these reserves run low, fatigue sets in, and the body may begin breaking down muscle protein for energy, a catabolic state that undermines training goals. Proper intra-workout nutrition helps by providing a quick, accessible source of carbohydrates to top up fuel and, in some cases, protein to protect muscle tissue from breakdown.
The Role of Carbohydrates
Carbohydrates are your primary energy source for high-intensity exercise. Consuming easily digestible carbs during prolonged activity helps to maintain blood glucose levels and spare muscle glycogen stores, delaying the onset of fatigue. The type and amount of carbs depend on the duration and intensity of the exercise.
- Simple vs. Complex Carbs: During exercise, simple, high-glycemic carbohydrates like dextrose or maltodextrin provide rapid energy. They are absorbed quickly and don't cause the same digestive distress as high-fiber, complex carbs. For events over two hours, a mix of glucose and fructose can enhance carbohydrate absorption, allowing for higher intake rates of up to 90g per hour.
- Recommended Intake: For exercise lasting 60-90 minutes, 30-60 grams of carbohydrates per hour is a good starting point. For longer durations (e.g., multi-stage races or ultra-endurance events), intakes may increase to 60-90 grams or more per hour, often requiring a mix of carbohydrate sources.
The Role of Protein and Amino Acids
While carbohydrates are the main focus, a small amount of protein or essential amino acids (EAAs) can also be beneficial, especially during very long or intense sessions lasting over two hours. Adding protein can help mitigate muscle breakdown and can also assist with recovery and performance, though it should be a secondary concern to carbohydrate intake during the session itself. Studies show that adding protein to a carbohydrate supplement can enhance muscle protein synthesis and promote a more positive net protein balance during recovery.
The Importance of Hydration and Electrolytes
Dehydration significantly impacts athletic performance, leading to fatigue and muscle cramps. As you sweat, you lose both water and crucial electrolytes like sodium and potassium. Replenishing these is vital for maintaining fluid balance, nerve function, and muscle contractions.
- Fluid Intake: For exercise over an hour, plain water may not be enough. Sports drinks containing electrolytes and carbohydrates help with faster absorption and replenishment. Aim to drink consistently throughout the session rather than waiting until you are thirsty.
- Electrolytes: Sodium is particularly important, as its concentration in sports drinks helps stimulate thirst and retain fluids. Many energy gels and chews also contain added electrolytes.
Intra-Workout Strategies for Different Disciplines
The ideal intra-workout strategy can vary depending on the type and intensity of your exercise. A short, intense weightlifting session requires less fueling than a long marathon.
Strength Training (Under 90 minutes)
For most strength sessions under 90 minutes, focusing on pre- and post-workout nutrition is sufficient. If you train in a fasted state or have an exceptionally long, high-volume session, a small amount of fast-acting carbs or EAAs can prevent a performance drop. Simple options include a sports drink or a handful of chews.
Endurance Training (Over 90 minutes)
Endurance athletes, such as marathon runners or cyclists, must prioritize continuous fuel delivery. A combination of liquids and easily transportable, low-fiber solids is often best to avoid flavor fatigue. Sports drinks, energy gels, chews, and dried fruit are popular choices.
Fueling Options Comparison Table
| Fuel Source | Primary Nutrient | Absorption Speed | Benefits | Considerations |
|---|---|---|---|---|
| Sports Drink | Carbohydrates, Electrolytes | Fast | Hydrates, replenishes carbs and electrolytes simultaneously. | Can be high in sugar; concentration needs to be optimal (e.g., 6-8%) to avoid GI issues. |
| Energy Gels | Concentrated Carbohydrates | Very Fast | Highly concentrated, portable, and quickly absorbed. | Can cause stomach upset if not consumed with enough water; taste fatigue is common. |
| Energy Chews/Blocks | Carbohydrates | Fast | Convenient, chewable format, often includes electrolytes. | Can require more chewing than gels, may not be ideal during high-intensity efforts. |
| Dried Fruit (e.g., raisins) | Carbohydrates, Minerals | Medium | Whole-food option, provides natural sugars and minerals. | Fiber content can cause GI distress for some, especially in large quantities. |
| Bananas | Carbohydrates, Potassium | Medium | Natural food, good source of potassium for muscle function. | Can be bulky to carry, delicate, and may cause GI upset during intense exercise. |
Implementing Your Strategy
- Practice in Training: Never try a new fueling strategy on race day. Use your long training sessions to experiment with different fuels and timing to see what your body tolerates best.
- Start Early: Begin fueling about 30 minutes into exercise rather than waiting for fatigue. This helps maintain blood sugar and glycogen levels proactively.
- Combine Sources: Mixing solid and liquid sources can help combat taste and flavor fatigue during long events.
- Listen to Your Body: Pay attention to hunger, thirst, and energy levels. Adjust your intake as needed based on the intensity and duration of your session.
Conclusion: The Final Word on Fueling Muscles in Motion
To feed muscle in motion effectively, athletes must prioritize carbohydrates for energy, maintain adequate hydration, and replenish lost electrolytes. For prolonged activities over 90 minutes, incorporating a small amount of protein can further protect muscle tissue. Developing and practicing a personalized intra-workout nutrition strategy during training is key to unlocking peak performance and preventing fatigue. The right fuel at the right time ensures your body has the energy it needs to power through its toughest demands, allowing you to train harder and recover more effectively. Your consistency in meeting daily macronutrient needs is the most crucial factor for maximizing training benefits.
International Society of Sports Nutrition (ISSN) position stand: protein and exercise
Key Takeaways
- Prioritize Carbohydrates: During workouts over 60-90 minutes, easily digestible carbohydrates are the primary fuel source to maintain energy and spare muscle glycogen.
- Stay Hydrated: Consistent fluid intake and electrolyte replenishment are critical for preventing dehydration and maintaining muscle function during prolonged exercise.
- Consider Protein: For sessions exceeding two hours, adding a small amount of protein or EAAs can help prevent muscle breakdown and support recovery.
- Practice Your Strategy: Test different fueling options and timings during training to find what works best for your body and specific exercise demands.
- Time Your Fueling: Start consuming fuel proactively about 30 minutes into your workout, rather than waiting for fatigue to set in.
