Your swimmer shows up with a pizza in their stomach, or hasn't eaten in six hours. You don't control their plate, but you can educate them. A practical before/during/after guide for club coaches.
Your swimmer shows up to practice having eaten a pizza twenty minutes before. Their legs are heavy by the first 200 meters, they're dragging through turns, and by mid-session they're asking if they can stop. You can't control what goes on their plate. But you can explain why it changes everything.
Nutrition is often seen as the dietitian's domain. In reality, a club coach doesn't need a nutrition degree to give reliable and useful advice. You just need to understand a few basic mechanisms, and know how to translate them into plain language for a 14-year-old or a masters swimmer eating on the run between meetings.
What follows can be passed on to your swimmers without ever stepping outside your role.
Swimming is one of the sports that burns the most energy per hour. Cold water forces the body to constantly produce heat. Water resistance simultaneously engages the arms, legs, and trunk stabilizers. And club sessions rarely last less than an hour.
The primary energy source for a swimming effort is muscle glycogen — the carbohydrates stored in muscles and the liver. When these reserves are insufficient, effort quality drops. Swimmers can't hold their split times. They shorten their stroke. They instinctively avoid intense exercises. Not from lack of motivation. Lack of fuel.
These figures are not targets to calculate gram by gram for each swimmer in your club. They serve to calibrate the message: most club swimmers eat too few carbohydrates for the intensity of their training. Not by choice, but by lack of awareness.
The ideal window is two hours before training. A complete meal (carbohydrates, protein, vegetables) eaten two hours before allows sufficient digestion without leaving the body short on fuel. Under one hour, the body is still actively digesting: blood flow to the digestive muscles competes with muscular needs.
What your swimmers should eat two hours before training: moderate glycemic index carbohydrates (rice, pasta, bread), a light protein source (chicken breast, egg, yogurt), little fat and little fiber — both slow digestion and can cause gastric discomfort in the water.
Many clubs offer slots at 6 or 7 a.m. Training on an empty stomach is then tempting, or simply unavoidable if the swimmer doesn't have time to eat. This is acceptable for a light endurance session (Z1-Z2), but problematic for an intense session.
Practical solution: advise your swimmers to have a small snack 30 to 45 minutes before leaving: a banana, a slice of white bread with honey, or a yogurt. Not enough to burden digestion, enough to prime glycogen reserves.
This is the swimming paradox: your swimmers spend an hour in the water and don't drink. The sensation of thirst is masked by immersion. The body doesn't "feel" dehydration the same way as in running or cycling. Yet swimmers sweat.
How many of them have a water bottle at the pool edge? And among those who do, how many touch it during the session? A pool at 27°C with 80% humidity is a sauna. Effort raises core temperature, the body sweats to regulate it, even if the swimmer doesn't feel it, even if they're in cold water. Maughan & Shirreffs (2010, Scandinavian Journal of Medicine & Science in Sports) measured fluid losses of 500 ml to over one liter per hour in competitive swimmers, depending on intensity and ambient temperature.
The practical rule for your group: a water bottle at the poolside, and an explicit instruction to drink every 20 to 30 minutes, during breaks, between sets. Don't wait until thirsty. If your swimmers wait until they're thirsty, they're already slightly dehydrated.
The session is over. But recovery is just beginning. In the 30 to 60 minutes following effort, the body is in active reconstruction phase: glycogen to replenish, muscle fibers to repair. This is the most useful window for eating. Most club swimmers waste it: they get out of the water, get changed, and don't eat anything for an hour or two. It's the easiest mistake to fix.
The post-session meal or snack must combine two elements: carbohydrates (to replenish glycogen) and protein (for muscle rebuilding). The recommended ratio is approximately 3 grams of carbohydrates to 1 gram of protein.
During training camps or peak periods, some groups swim morning and evening. The recovery window between the two sessions is then critical. If your swimmers don't eat properly after the morning session, they'll arrive at the evening session with incomplete reserves. The second session will be poor quality, whatever their motivation.
Concrete instruction for camps: full meal within the hour after the morning session, light snack 1 hour before the evening session. Don't assume your swimmers know this. Say it.
Certain nutritional behaviors show up in almost every club. Identifying them lets you intervene with a simple, precise message.
Competition is not an ordinary training session. Stress increases resting energy expenditure. Waiting times between events create unusual nutritional windows. And the consequences of poor management are immediate and measurable on the clock.
| Criteria | Training | Competition |
|---|---|---|
| Main meal | 2 h before the session | 3 h before the first event |
| Meal size | Normal, balanced | Lighter, simple carbs preferred |
| Fats and fiber | Moderate | Minimize |
| New foods | Possible | Never — stick to familiar foods |
| Hydration | Bottle during session every 30 min | Drink regularly between events |
| Between events | N/A | Fast carbs (banana, bar, juice) if wait > 1 h |
| Coffee / stimulants | As usual | Only if habitual — no experimentation |
The golden rule of competition: no dietary experimentation on race day. Everything your swimmer eats at a competition must have been tested in training. An unfamiliar food can cause digestive discomfort at the worst moment.
In the week before an important competition, training volume decreases. But nutritional needs remain high. This is a common mistake: swimmers eat less because they're training less, when their body is precisely in the process of rebuilding its reserves.
During the taper phase, maintain carbohydrate intake at ≥ 6 g/kg/day even if training volume has dropped 30 to 40%. The caloric deficit can be absorbed by slightly reducing fats, not carbohydrates. The goal is to arrive at the competition with saturated glycogen reserves. This is precisely the period when the body has the capacity to fully replenish them.
Your role is not to prescribe personalized meal plans. That requires specific training. For swimmers with particular needs (eating disorders, medical conditions, high performance goals), directing them to a healthcare professional remains the right decision.
But explaining to your swimmers why eating two hours before the session improves their split times, why drinking between sets is not optional, and why the post-training snack is not a luxury — that's entirely within your scope. And it's often what's missing in clubs where nobody ever talks about it.
Your swimmer who showed up with pizza legs at the first 200 meters: they don't know what they don't know. It's your job to tell them. Not a lecture. Just: "What did you eat before coming? How long before?" Two questions. Asked once a week for a month. That's often all it takes for a swimmer to start making the connection between what they put on their plate and what they produce in the water.
Ideally, a full meal 2 hours before the session. Under one hour, the body is still actively digesting, which can cause discomfort in the water (nausea, side stitch, heaviness). If the slot doesn't allow 2 hours, a small light snack (banana, yogurt, slice of bread) 30 to 45 minutes before is a good compromise, especially for morning sessions.
Yes. The sensation of thirst is masked by immersion, but the body sweats to regulate the heat produced by effort, even in cold water. Estimates vary by intensity and water temperature, but losses of 500 ml to over one liter per hour are common. A water bottle at the pool edge with an instruction to drink every 20 to 30 minutes is essential.
In the 30 to 60 minutes after the session, a snack combining carbohydrates and protein is ideal. Simple examples: banana + Greek yogurt, chocolate milk, bread + ham + fruit juice. The goal is to replenish muscle glycogen (role of carbs) and start muscle rebuilding (role of protein). If a full meal follows directly, it replaces the snack.
For long competitions or multi-event meets, slightly increasing carbohydrates in the 48 hours beforehand (D-2 and D-1) is a strategy validated by sports physiology. In practice: slightly more rice or pasta at meals, without forcing. For a short event (a single 100 m), carb loading doesn't provide a measurable benefit. The key is not to reduce intake during the taper phase.
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