Why Your Brain Needs Different Fuel for Swimming vs. Running: A Mental Health Athlete's Guide to Race-Day Nutrition

The difference between a good and a great race goes beyond merely training more. Whether you’re a runner or swimmer, as an athlete, you train your heart, lungs and legs for months on end, but it’s just as crucial to train the brain.

Nutrition plays a huge role in an athlete’s performance. It’s not just about fueling. Nutrition optimizes brain function and supports mental clarity. What you eat can influence your psychological state throughout the race, from the start to the finish line. Knowing what to eat before running and swimming, and when, can build a strong and resilient brain.

How Exercise Impacts Your Mental State

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Both running and swimming are cardiovascular exercises. However, they are different sports that trigger different physiological and neurological responses. As such, you will need a different set of nutritional approaches to achieve mental acuity during the race.

The Neurochemical Reward

Sustained aerobic exercise is great for your brain chemistry. These activities release endorphins, which can produce euphoria-like effects and reduce pain perception. A key example is the runner’s high. These exercises also boost serotonin and dopamine levels, which help regulate your mood and enhance the reward system. They are also great for fighting depression.

Brain-Energy Connection

For athletes, peak performance is no longer just about pushing through limits. It’s about proactively managing the body's fuel and energy systems. This reflects a wider societal change —  the turn from disease prevention toward a more proactive approach to health is one of the biggest shifts in the 21st century. During races, applying this proactive mindset means the mind’s well-being should be just as well looked after as the physical.

The brain is an energy-intensive organ that consumes glucose for energy even at rest. An unstable blood sugar can introduce a host of negative mental feelings/emotions, such as sadness, irritability and mood swings. These events act as an alarm from the brain.

Exercise also improves the body’s stress response. It lowers cortisol levels at rest, so you generally feel calmer and less anxious. Proper nutrition helps prevent exercise from becoming a stressful event for the body, as an underfueled exercise session can make cortisol levels rise and negatively affect your mental health.

Like-Minded Communities

Exercise opens up avenues for social connection. With people to support your journey, you may experience greater heights of achievement than you previously thought possible. For example, Still I Run is a powerful network of athletes who use running to improve their mental health. Members encourage one another in their journeys, including during the Run. Write. Fight Program or Starting Line Scholarship.

What to Eat Before Running

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Running is a high-impact activity. It is gravity-intensive, and it can rapidly deplete your glycogen stores. In the middle of a race, you might notice that your brain needs a steady stream of glucose from the bloodstream. You might be more indecisive, have more negative thoughts, or find the activity itself requires more effort.

Mental Clarity Menu for 1-2 Hours Before the Race

Running results in a constant jostling, which makes the stomach highly sensitive to heavy meals before the race. If that’s the case, a banana is a great option as it provides fast-acting carbohydrates and is easy on the stomach. It is also a rich source of potassium, an important ingredient for nerve signaling and muscle function.

Another option is a small bowl of instant oatmeal, which provides a significant amount of easily digestible carbohydrates. Additionally, oatmeal provides sustained glucose release, which is especially helpful during the first few miles of the run. Like bananas, oatmeal  also doesn’t weigh you down like heavy meals.

A Runner’s Daily Diet

Long before efore the day of your run, you pave the way for a resilient brain through proper nutrition. Dietary protein provides the amino acids the brain needs. Tryptophan is crucial for serotonin production and is commonly found in turkey, peanuts and pumpkin seeds. 

What to Eat Before Swimming

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The body’s core temperature is around 98.6°F, but most competitive pools are colder. This temperature difference between your body and the pool creates a constant, significant toll on the body as it tries to keep warm. A swimmer experiences constant energy drain from depleted mental reserves. You might experience a slow loss of pace, form and rhythm.

Cognitive Fuel Menu for 1-2 Hours Before the Swim

Swimming is a low-impact sport, so your digestive system can be more stable during the race. You can eat more substantial foods that provide sustained release for muscle burn and thermoregulation.

A tasty and nutritious pre-swim meal is grilled chicken with vegetables on the side, such as carrots, potatoes or broccoli. Another meal option is Greek yogurt topped with nuts, as this provides a good balance of protein, carbohydrates and healthy fat. Both options help provide sustained energy levels for peak performance while swimming. 

If you want a drink option, a small fruit and spinach smoothie can be the perfect solution. Blending these ingredients to make them easier to digest. The fruit offers healthy nutrients and simple carbohydrates for quick energy.

Prevention Against Dehydration

The human body is comprised mostly of mostly water. When you are dehydrated, brain tissue shrinks while muscles cramp, leading to lethargy. Even mild dehydration can cause a drastic decline in cognitive performance. Without proper hydration, you might experience brain fog and mental fatigue, which can make the race more difficult.

You sweat even while swimming, causing you to lose both water and electrolytes. The body perspires to cool down, and the pool water just masks this effect. As such, you need to be properly hydrated. Dehydration can significantly impact cognitive function, reaction time and concentration. All these factors are highly critical during a race. Chugging right before can cause uncomfortable stomach sloshing as you move. 

Make sure to constantly sip water or an electrolyte drink before, during and after a swim to ensure mental sharpness. Electrolytes replenish your body with the essential minerals like sodium, potassium and magnesium. 

Low sodium levels can lead to confusion and poor coordination, while low potassium levels can increase feelings of anxiety. Lastly, magnesium calms your nervous system.

Your Race-Day Mental Health Nutrition Plan

You shouldn’t introduce anything new on a race day. You don’t know how your body is going to react or perform when you eat or drink a new food. Every factor should be tested and refined during training to give you a clearer idea of your food tolerance and response. This also ensures that you achieve peak performance during the race.

3-4 Hours Before

For the first three to four hours before a race, make sure to eat a well-balanced meal. Include complex carbs, sufficient protein and low fat. An example would be a grilled chicken with sweet potato and steamed vegetables.

1-2 Hours Before

An hour or two before the race, make sure to consume simple and fast-acting carbohydrates if you are a runner. Examples are a banana and an energy gel. For swimmers, it’s best to eat a combination of simple and complex carbs with a little bit of protein or fat mixed in. Consider half a serving of Greek yogurt with a small handful of berries.

Post-Race Recovery

After the race, it’s essential to recover by eating carbohydrate and protein-rich food sources. These will help to  replenish your glycogen stores. Amino acids can be found in foods like chicken, quinoa, eggs and fish, and can help repair muscles and support the production of helpful neurotransmitters. 

Since intense exercise can cause systemic inflammation in the body, it’s important to focus on eating foods that support your brain's long-term cognitive health and are rich in omega-3 fatty acids, such as:

• Fatty fish: Fish such as salmon, mackerel, tuna and herring help reduce blood levels of beta-amyloid, which form clumps in the brains of Alzheimer's patients.

• Walnuts: These nuts provide ample protein and healthy fats.

• Dark leafy greens: They’re rich in vitamin K, lutein, folate and beta carotene. 

• Berries: Strawberries, blueberries and other berries may help improve memory.

Fuel Your Body, Lead Your Mind

Your nutrition is one of the most powerful variables you can control for peak performance during a race. What to eat before running is all about focusing on food that provides quick energy stores without being heavy on your stomach. 

On the other hand, what to eat before swimming focuses on a mix of simple and complex carbohydrates. In both instances, nutrition plays an important role in keeping your brain focused and powerful. After all, it is the organ responsible for commanding the entire body.

By learning how to train your brain as well as other body parts, you’re unlocking a new aspect of being an athlete. Both your brain and body can work together toward achieving a common goal. Try eating these suggested foods at the right time and note down how your performance improves. These changes can truly help you transform into a stronger and healthier version of yourself. 

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Beth Rush is the fitness editor at Body+Mind. She writes about how women with PCOS can hack their exercise routines to balance hormones naturally. She covers topics like plant-based recipes for athletes and preaching the benefits of green exercise. You can find Beth on X @bodymindmag.