Triathlon
How to manage carbohydrate intake during extended events to prevent bonking and sustain power.
In endurance events, steady carbohydrate strategies are essential to avoid bonking, maintain energy, and preserve performance. This guide translates science into practical, race-tested approaches for athletes aiming to optimize fueling across long efforts, races, and multisport days.
August 08, 2025 - 3 min Read
Carbohydrate management begins long before the gun goes off. Athletes often underestimate how critical timing, type, and amount are for sustaining pace in long events. To begin, establish a baseline based on body weight, training history, and event duration. A practical starting point is 40–60 grams of carbohydrate per hour for events under four hours, increasing toward 90–120 grams per hour as intensity and duration extend. Distribute intake evenly and test different formats during training to find tolerances. Hydration, electrolyte balance, and stomach comfort all interact with carbohydrate absorption, so consider an integrated fueling plan that aligns with your daily nutrition.
The digestion of carbohydrates is not universal; different sources work better for different athletes. Fast-dasting glucose polymers, fructose blends, and Maltodextrin-based formulations each have pros and cons. For many, a mix of glucose and fructose can unlock higher carbohydrate absorption rates without overloading the gut. Having real foods, such as bananas, dried fruit, or energy bars, alongside sports drinks can also help if you tolerate them well. Practice this during long rides and brick sessions to gauge how well your stomach handles simultaneous intake and exercise. Remember that taste, texture, and portability influence consistency just as much as macro ratios.
Customize your carbohydrate plan around pace, terrain, and weather conditions.
Cadence matters as much as what you eat. Establish a fueling rhythm that mirrors your cadence on the bike and run. For example, take in a small amount every 15–20 minutes on the bike, and every 20–30 minutes on the run, adjusting for pace and terrain. If you experience fatigue, your body may be signaling a mismatch between intake and energy demand. Consider using a simple formula: carbohydrates per hour plus fluids, adjusted for temperature and sweat rate. Keep education about gut tolerance in mind, and avoid surprises by rehearsing your plan in training with similar effort levels to race conditions.
In long events, fat and protein play supporting roles, but carbohydrates remain the primary energy source. A well-rounded plan includes a modest amount of protein to support muscle repair during prolonged activity and recovery afterward. Some athletes find that small protein-containing snacks during ultra events can help reduce appetite fatigue and improve overall energy consistency. The key is to introduce these options gradually during training so they don’t disrupt digestion. Balance these with carbohydrate-dense choices and adequate hydration. If your stomach reacts poorly to dairy or specific proteins, seek plant-based or non-dairy alternatives that fit your tolerance window.
Build a structured routine that reduces decision fatigue mid-race.
Weather, heat, and humidity can alter how quickly you process carbohydrates. In hot conditions, gastric emptying may slow, while dehydration can amplify GI distress. A practical adjustment is to slightly reduce solid foods and rely more on liquids and gels when heat spikes. In cooler conditions, you may tolerate denser, solid sources with less risk of GI upset. Track how your body responds to different environments during long training sessions and adjust your hourly target accordingly. The goal is a reliable, predictable intake that supports steady power rather than chasing peaks or fighting fatigue from a depleted gut.
Practice, measure, and refine your plan using objective feedback. Keep a fueling log that pairs intake with perceived effort, GI comfort, and performance outcomes. Record the exact products, volumes, and timing you used during each training session. If performance flags occur, review what you consumed in the preceding hour and consider whether the carbohydrate type, concentration, or osmolality may have influenced digestion. Small tweaks—such as spacing out portions or swapping product brands—can yield meaningful improvements. Regularly testing different formulations helps you establish a robust, personalized system that survives race-day pressure.
Monitor hydration and electrolyte balance alongside carbohydrates.
A simple routine minimizes cognitive load and preserves focus for critical moments. Map out your planned intake at the start of the race and practice it during long workouts. For example, set a timer on your watch for regular fueling intervals and keep your fluids and gels within easy reach. If your event features frequent aid stations, decide whether to supplement with your own preferred products or use provided options as a backbone while adding your own small extras. The aim is predictability: you shouldn’t have to improvise when your energy is sinking or your form is deteriorating.
Gut comfort is the gatekeeper of performance. A flawless plan on paper is useless if your stomach rebels under load. Construct a gut-friendly strategy by gradually exposing your body to carbohydrate loads during long training sessions, then increasing intensity to race conditions while maintaining hydration. Consider enzyme-rich or low-FODMAP options if you’ve shown sensitivity to certain sugars. Always practice carb timing with your current shoes, apparel, and fueling kit to confirm you can access input without interruption. If GI distress arises, pause to reassess the type, amount, and timing before continuing.
Establish a post-race recovery fueling protocol to rebound quickly.
Fluids and electrolytes influence how well your body handles carbohydrate transport. Dehydration reduces gastric emptying and can amplify GI discomfort, limiting intake when you need it most. Establish a baseline hydration plan, aiming for steady urine color and regular thirst cues as guides. Pair this with electrolytes to maintain fluid distribution and prevent cramping, especially in long, sweaty efforts. Carbohydrate absorption can be hindered by imbalanced osmolality, so choose drinks that support both hydration and energy delivery. Tailor your plan to weather, sweat rate, and body size, then test it across training sessions.
In practice, many athletes benefit from a realistic mix of beverages and solids. A waterfront tasting tour of flavors and textures helps you settle on a routine that your gut tolerates. Consider alternating between sports drinks, gels, chews, and whole-food options such as dried fruit or rice cakes. The goal is redundancy: if one source becomes unavailable, another will supply the needed carbohydrate. Maintain consistent pacing and ensure your intake cadence matches effort, so you don’t oversupply or undersupply during intense segments or transitions.
Recovery fueling is as important as fueling during the race. After extended efforts, muscles need readily digestible carbohydrates to replenish glycogen stores and support immune function. A practical plan pairs fast-acting carbs with protein to stimulate repair and reduce soreness. Aim for a 3:1 or 4:1 carbohydrate-to-protein ratio in the first hour post-exercise, followed by a balanced meal later. Hydration should continue, with electrolytes if sweat losses were high. Reassess your training block’s fueling approach using feedback from your post-race fatigue levels and appetite signals to guide refinements for the next event.
Long-term improvement comes from disciplined, iterative testing of fueling strategies. Create a schedule that slots carbohydrate experiments into easy, moderate, and hard sessions, then document the outcomes. Seek input from coaches or peers who understand endurance fueling. Track metrics beyond pace, such as stomach comfort, perceived exertion, sleep quality, and recovery markers. Incremental changes—small increases in hourly carbohydrate intake or slight adjustments to timing—gradually reveal the most effective plan for you. With patience and consistent practice, you can build a fueling approach that sustains power across all phases of extended events.
