Fall race season is here, and training logs across the country are tapering toward finish lines. But for every athlete who's put in the miles, there's a fueling plan that hasn't received nearly the same attention. That gap shows up on the course. GI distress, early bonking, cramping, and the slow fade in the final miles are rarely about fitness. Most of the time, they're about nutrition choices made in the hours before and during the event.
These aren't rare mistakes. They're the same five errors that coaches and sports dietitians see race after race. Here's what they are and exactly how to fix them before your next start line.
Mistake 1: Eating a Large, Unfamiliar Pre-Race Meal
Race morning feels high-stakes, and that pressure pushes a lot of athletes toward meals that sound responsible. A large bowl of oatmeal with nut butter, a protein-heavy scramble, or a fiber-rich smoothie can all seem like smart choices. But if those foods aren't part of your regular pre-training routine, your gut doesn't know them. And a nervous gut under race stress knows even less what to do with them.
GI distress is one of the most common causes of underperformance in endurance events, with research showing it affects anywhere from 30 to 90 percent of athletes in races exceeding 90 minutes. The culprits are usually high-fat, high-fiber, or high-protein foods consumed within two to three hours of effort. Fat and fiber slow gastric emptying. High protein adds digestive load when blood flow is already being redirected to working muscles.
The fix is straightforward: eat what you've practiced. Your pre-race meal should be a near-identical copy of what you've eaten before your longest training sessions. Keep it carbohydrate-dominant, moderate in protein, low in fat and fiber, and timed at least two to three hours before the gun. White rice, a plain bagel with minimal topping, or a banana with a small amount of peanut butter are all tried-and-true options precisely because they're boring and predictable. Boring is what you want from your stomach on race day.
Mistake 2: Waiting Too Long to Start Fueling
Here's how it usually goes: the race starts, you feel great, and fueling feels unnecessary. By mile six, things have shifted. By mile nine, you're managing the clock instead of running it. That sequence has a physiological explanation, and it's almost entirely preventable.
Muscle glycogen, your body's primary fuel source during sustained aerobic effort, begins to deplete within 45 to 60 minutes of continuous moderate-to-high intensity exercise. Your liver glycogen, which maintains blood glucose levels, runs its own parallel drawdown. Once both reserves are significantly reduced, performance drops and recovery during the event becomes nearly impossible. You can't eat your way back from a bonk mid-race. You can only slow the deterioration.
Current sports nutrition guidelines recommend beginning carbohydrate intake between 30 and 45 minutes into any event lasting longer than 60 to 75 minutes. That means your first gel, chew, or sports drink should be going in while you still feel strong. For events over two hours, the target is 60 to 90 grams of carbohydrates per hour, ideally from multiple carbohydrate sources (glucose and fructose together) to maximize absorption and minimize gut load.
Set a fueling timer before you start. Don't rely on hunger or feel. By the time those signals arrive, you're already behind.
Mistake 3: Over-Hydrating With Plain Water
Hydration advice has been simplified to the point of becoming dangerous. "Drink plenty of water" is technically correct, but for athletes competing in events lasting over 90 minutes, drinking exclusively plain water can cause more problems than it solves.
Hyponatremia, a condition in which sodium levels in the blood drop to abnormally low levels, is a real and underappreciated risk in endurance sport. It occurs when fluid intake outpaces sodium replacement, diluting the blood's electrolyte concentration. Symptoms range from nausea and headache to confusion and, in severe cases, seizures. Studies from large marathons have shown that a meaningful percentage of finishers cross the line with clinically low sodium, with recreational runners at higher risk because they tend to drink more relative to their sweat rate.
The fix isn't to drink less. It's to drink smarter. In events exceeding 90 minutes, your hydration strategy should include sodium alongside fluids. That can come from electrolyte tabs, sports drinks with sodium content listed on the label, or salted whole-food options at aid stations. A general benchmark is 500 to 700 milligrams of sodium per hour during prolonged effort in moderate conditions, with higher targets in heat or for athletes who are heavy sweaters.
This applies equally to runners and to HYROX athletes, whose combined cardio and resistance format often creates significant sweat losses over competition windows of 60 to 90 minutes. Plain water at every station isn't a fueling strategy. It's a habit that needs adjusting.
Mistake 4: Practicing Your Fueling Plan for the First Time on Race Day
Sports nutrition isn't a set-and-forget system. Your gut is trainable, and the products, timing, and volumes you plan to use on race day need to be rehearsed during training. This is one of the most consistently ignored pieces of race preparation, and it's one of the most consequential.
Different gels sit differently. Some athletes tolerate fructose-heavy products well; others experience cramping or bloating. Certain electrolyte formulas work at low intensities but cause nausea when heart rate climbs. The only way to know what your body accepts at race pace is to test it at race pace, during training, repeatedly.
Build your fueling rehearsals into your longest training days, specifically the sessions that mirror race conditions in duration and intensity. Use the exact products you plan to carry on race day. Test the timing intervals you intend to follow. If the race course uses a specific brand at aid stations, either train with it or carry your own. Gut adaptation takes time, but it does happen. Athletes who train their nutrition alongside their fitness arrive at the start line with two systems prepared instead of one.
This kind of deliberate preparation mirrors the broader principle of practicing under realistic conditions, the same logic that makes technique and feedback such an effective pairing for preventing injury in strength and conditioning work.
Mistake 5: Ignoring the 30-Minute Post-Race Window
The race ends and the focus immediately shifts to celebration, medal photos, and finding your bag. Recovery nutrition is the last thing on your mind. But the 30-minute window after a sustained effort represents one of the highest-leverage opportunities in your entire training cycle, and most athletes waste it.
After depleting glycogen stores and creating muscle protein breakdown over the course of a race, your body enters a state of elevated insulin sensitivity and heightened nutrient uptake. Muscle tissue is primed to absorb carbohydrates for glycogen resynthesis and protein for repair. Research consistently supports consuming a combination of fast-digesting carbohydrates and 20 to 40 grams of protein within 30 to 60 minutes of finishing.
Solid food works, but it's often the last thing athletes want immediately after crossing the line. A recovery shake, chocolate milk, or a pre-packed snack bag with a banana and a protein source are all practical options that don't require planning in the moment. The goal is to bridge the gap until your first full recovery meal, not to replace it entirely.
For athletes who race frequently or are managing the compounding demands of a full fall schedule, recovery nutrition becomes even more critical. The strategies that support long-term consistency go well beyond the course. The post-workout recovery habits that matter most after 35 offer a useful framework for athletes building these practices into their weekly routine.
It's also worth noting that sleep quality has a direct effect on glycogen restoration and hormonal recovery. If your fall race schedule is already compressing your rest, how fall schedule shifts quietly affect your sleep is worth understanding before the cumulative deficit catches up with your performance.
One More Variable You Might Be Overlooking
Fueling at altitude or in unusual environmental conditions adds another layer of complexity that flat-course race plans don't account for. Carbohydrate oxidation, appetite, and hydration needs all shift in mountain environments. If your fall calendar includes a trail race or high-elevation event, understanding how altitude changes your nutritional needs can prevent a surprise drop in performance that has nothing to do with your fitness.
The Bottom Line
Race-day nutrition isn't where you experiment. It's where you execute a plan you've already stress-tested in training. The five mistakes above aren't signs of inexperience. They're signs of incomplete preparation. And preparation is something every athlete at every level can control.
Dial in your pre-race meal. Start fueling before you feel like you need to. Replace sodium, not just fluid. Practice your products during training. Recover deliberately in the window after you finish. Those five adjustments won't just protect you from a bad race. They'll move the ceiling on what a good one looks like.