NOVAFIT ENERGY · Performance · Nutrition · Science
Most of the digestive and performance problems athletes suffer in a race are not bad luck. They are the predictable result of avoidable decisions.
There is a conversation that repeats in every running group, in every cycling club, in every trail community. Someone tells how their stomach failed at the last race. That they had to stop. That they couldn't eat. That gels feel bad while racing but fine in training. That they don't understand why.
The answer almost always has the same structure: it is not bad luck or individual intolerance. It is physics and physiology. And the mistakes that cause it are, for the most part, completely avoidable.
Mistake 1: trying the gel for the first time on race day
It is the most common and the most costly mistake. The athlete chooses their race nutrition based on reviews, on what a training partner uses, or on what was available at the expo. And on race day, they try it for the first time.
The problem is not just that the gel might sit badly. It is that the digestive system needs training, just like the muscles. The ability to absorb carbohydrates during exercise — especially at the doses needed in long efforts — improves with repeated practice. A gut that has not been trained to process 60-90 g of CHO per hour under effort will tend to produce discomfort, regardless of the quality of the gel.
The rule is simple: any product you plan to use in competition must have been tested at least 4-6 times in long training sessions, under similar intensity conditions. No exceptions. Race day is not the time to experiment.
Mistake 2: starting to eat too late
Intuition says: "I eat when I'm hungry." Physiology says the opposite.
When the athlete feels hunger during exercise, blood glucose has already dropped. Glycogen stores are at critical levels. The digestive system is under maximum physiological stress. And at that moment — when intake feels most urgent — the ability to absorb nutrients is the lowest of the entire effort.
The correct protocol is preventive, not reactive. In efforts of more than 60-75 minutes, intake must start between minute 30 and 45, before the body registers any deficit signal. And it must be maintained regularly — every 30-45 minutes — regardless of how the athlete feels.
Eating to replenish is exponentially harder than eating to prevent. An ischemic gut, with low blood glucose and the nervous system on alert, processes nutrients at a fraction of its normal capacity. The gel that absorbed perfectly at minute 30 can, at minute 90 with a deficit, cause exactly the discomfort the athlete is trying to avoid.
Mistake 3: not hydrating properly when taking the gel
A gel without water is a hyperosmotic solution in the intestine. When the solute concentration in the intestinal content is higher than in the blood, the body reverses the absorption process: instead of moving water from the gut into circulation, it draws water out of circulation into the gut to balance osmolality. The result is the opposite of what was intended: more pressure in the intestine, greater risk of discomfort, and in some cases osmotic diarrhea.
The practical rule: each gel must be taken with 150-250 ml of water. Not after. Together with the gel, or immediately before. That amount of water dilutes the intestinal content to an osmolality the intestine can handle efficiently.
The exception is isotonic gels, formulated with built-in water and adjusted osmolality. But even in those cases, continuous hydration is essential to maintain plasma volume and cardiovascular efficiency.
Mistake 4: ignoring sodium until the cramps show up
Muscle cramps during exercise have multiple causes, but one of the most common and most ignored is sodium deficit. Many athletes only think about electrolyte replenishment once cramps are already present — and at that point, the accumulated loss has been building for hours.
Worse still: the athlete who drinks only water — with no sodium — during prolonged efforts can aggravate the problem. Ingesting large amounts of water without electrolytes dilutes blood sodium, which can trigger hyponatremia even in someone who has drunk abundantly. It is one of the reasons why "drink a lot" without an electrolyte strategy can be worse than drinking less.
Sodium replenishment, like carbohydrate replenishment, must be periodic and preventive. A gel with 400 mg of sodium per dose — in the most bioavailable form — integrated into the nutrition protocol from the start, keeps the electrolyte balance continuous without needing additional salt tablets.
Mistake 5: using in a race what works in a short training session
This is perhaps the most subtle mistake. A gel can work perfectly in a 45-minute session and trigger digestive rejection at kilometer 50 of an ultra. It is not that the gel has changed. The athlete's physiological state has.
In short efforts, intestinal blood flow is only moderately reduced. The intestinal barrier is intact. Gastric pH is normal. Intestinal motility is functioning. Under those conditions, the gut can handle ingredients that would otherwise cause problems: artificial additives, thickeners, sweeteners, preservatives.
After four, six or eight hours of intense effort, that same gut is under an accumulated physiological stress that reduces its tolerance capacity. What previously passed without consequence can now trigger a local inflammatory response, nausea or active rejection.
The real test of a gel is not how it feels at kilometer 10. It is how it feels at kilometer 70, with five hours of effort behind you, in the heat, with the gut already compromised. That is the test that matters. And to pass it, the ingredients have to be the kind the intestine can process even in its worst conditions.
Mistake 6: thinking race nutrition starts at the start line
What happens in the two or three days before the race has a direct impact on how the body responds during effort. Glycogen reserves are loaded — or not — in that window. Hydration status and electrolyte levels at the start depend on what was done before, not on what is taken at the first aid station.
In the same way, recovery from previous efforts — arriving at the start with unresolved accumulated muscle damage, low-grade inflammation, an already activated immune system — predisposes to a less robust physiological response to the effort.
Race nutrition does not start with the first gel. It starts in the loading phase, in the dinner the night before, in the pre-race breakfast. All of that is part of the strategy.
The six mistakes described here are not negligence. They are the natural result of an industry that for decades has sold sports nutrition as if it were an accessory — something added at the last moment, chosen by flavor and taken when the body asks for it.
Real sports nutrition does not work like that. It is a system. It has physiological logic. It is trained. It is planned. And when it is done well, it does not "turn out fine" by chance: it turns out fine because it had to.
Your body does not improvise. Your nutrition shouldn't either.
NovaFit Energy — novafitenergy.com — @novafitenergy
Sant Feliu de Llobregat, Barcelona · Artisans of performance for twelve years
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