Fueling by Exercise Duration
The amount of carbohydrates you should consume per hour is not a one-size-fits-all number. It depends heavily on the duration and intensity of your physical activity. The body stores carbohydrates as glycogen in the muscles and liver, but these stores are finite. For endurance events, replenishing these stores during exercise is essential to maintain blood glucose levels and delay fatigue.
Shorter, High-Intensity Efforts (<60 minutes)
For workouts lasting less than an hour, your body's pre-existing glycogen stores are usually sufficient. However, some research suggests that a small intake of carbohydrates or even a carbohydrate mouth rinse can still offer performance benefits during high-intensity sessions lasting 45-60 minutes. This practice can trick the brain into thinking fuel is available, potentially enhancing motor output.
Moderate Duration (60-120 minutes)
As your activity extends beyond an hour, your glycogen stores begin to deplete significantly. To sustain energy levels and prevent a drop in performance, a carbohydrate intake of 30-60 grams per hour is generally recommended. This can be achieved through various sports nutrition products or real foods.
Longer Endurance Events (>120 minutes)
For long-distance activities such as marathons, ultra-endurance cycling, or triathlons, fueling needs increase substantially. For these events, athletes should aim for a higher intake of 60-90 grams of carbohydrate per hour. Elite or highly-trained athletes may even be able to tolerate and benefit from up to 120 grams per hour, but this requires specific gut training and the use of multiple types of carbohydrates.
Optimizing Your Fueling Strategy
The Importance of Multiple Carbohydrate Sources
When pushing towards the higher end of hourly carbohydrate intake (e.g., 90-120g), relying solely on one type of sugar can lead to gastrointestinal distress. The body can only absorb a certain amount of glucose per minute. However, by combining different types of carbohydrates—most commonly glucose and fructose—the absorption rate can be increased significantly because they use different transporters in the intestine. This multiple transportable carbohydrate strategy is key for high-performance fueling.
The Art of Gut Training
Just like you train your muscles, you can train your digestive system. Consistently practicing your fueling strategy during training sessions prepares your gut to handle and absorb larger quantities of carbohydrates on race day. A trained gut can minimize stomach issues like bloating, cramping, and nausea, which can derail performance. Start by gradually increasing your hourly intake in training and find what works best for your body.
Timing Your Carbohydrate Intake
To maximize absorption and prevent energy crashes, it's best to start fueling early and consistently. Instead of waiting until you feel tired, begin consuming carbohydrates within the first 30-45 minutes of exercise. From there, aim for regular, smaller intakes every 15-30 minutes, rather than consuming a large amount all at once. This drip-feed approach keeps energy levels steady and reduces the load on your digestive system.
Fueling Options Comparison
| Fuel Type | Carbohydrate Content | Digestion Speed | Best For | Considerations |
|---|---|---|---|---|
| Energy Gels | 20-40g per packet | Very Fast | High-intensity efforts, long events where convenience is key | Requires water, different brands offer varying compositions |
| Sports Drinks | Variable (often 6-8% carb solution) | Fast | All durations, provides fluid and electrolytes | Can be difficult to carry enough for very long events |
| Energy Bars/Chews | 30-60g per bar/serving | Moderate | Lower intensity, longer events where solids are tolerated | Can be hard to chew during high-intensity efforts, may cause stomach upset |
| Natural Foods (e.g., Bananas) | ~25g per medium banana | Moderate | Training, lower intensity efforts | Less compact, can be harder to eat on the move |
Sample Fueling Plan for a Long Endurance Race
- Pre-Race (3-4 hours prior): A carbohydrate-rich meal to top off glycogen stores, such as pasta, rice, or oatmeal.
- Pre-Race (30 minutes prior): 20-30g of fast-acting carbs like an energy gel or chews.
- During Race (Hourly): 60-90g of carbohydrates from a mix of sources, such as:
- Hour 1: Begin with an energy gel and sips of sports drink.
- Hour 2: A different flavored gel or some chews, plus more sports drink.
- Hour 3: Introduce a high-carb mix in a water bottle for a steady supply, complemented by another gel.
- Continuous: Consistent sips of water or electrolyte drink every 15-20 minutes to aid in carbohydrate absorption and hydration.
Conclusion
For optimal performance in endurance events, actively managing your carbohydrate intake is non-negotiable. Knowing how many carbs can you consume per hour is the first step, with general guidelines ranging from 30-60g for moderate efforts to 60-90g+ for extended, high-intensity activities. By incorporating the right mix of carbohydrate types, training your gut to improve tolerance, and starting your fueling strategy early and consistently, you can avoid hitting the dreaded wall and unlock your true potential. Experimenting with different products and timings during training is crucial to find a personalized strategy that works for you on race day.
For further reading on sports nutrition strategies, visit the National Institutes of Health (NIH) at https://pmc.ncbi.nlm.nih.gov/articles/PMC4008807/.
