Performance nutrition

Nutrition may not create a good athlete, but it could be one of the factors that make a GREAT athlete. Sports performance is mostly determined by genetic potential, training, and psychological drive. Nutrition is one of those ‘X’ factors that can put one athlete above another. Nutrition plays a vital role in fueling the body to be able to train, replacing any losses that occur as a result of training, allowing for training adaptions to happen, and ensuring proper hydration. Inadequate nutrition at any of these points will have a negative effect on athletic performance.


Our body needs energy to perform basic physiological functions, but when we exercise, our need for energy increases drastically. The amount of energy that our body uses depends on the intensity and duration of the exercise. During exercise, carbohydrates are our body’s preferred energy source, but we can also get energy from fat. We can store energy in the muscle and liver, which is the initial source of energy utilized when exercising. Once our energy stores are depleted, the body relies on energy in the blood, which is maintained by eating food.

For optimal performance, you want to ensure that you start every exercise session will full energy stores to delay the time to fatigue. This means that you need to fuel up before training. You can do this the day before exercise by providing foods rich in carbohydrates throughout the day and ensure that you have a carbohydrate-based snack or meal before an exercise session.

For endurance exercise (lasting more than 90 minutes), you will likely deplete energy stores and need to provide energy through eating to fuel the rest of the exercise session. If you don’t provide energy, your exercise performance will decline. Once the exercise session is complete, you then need to replace energy stores. Eating carbohydrate-rich foods immediately after exercise will help with fast energy replenishment. This is particularly important if you will be training again in less than eight hours. If your next exercise session is only in 24 hours, eating regular meals that contain carbohydrates throughout the day will help to ensure adequate replenishment.

Ensuring that you provide a sufficient amount of fuel before, during, and after exercise is crucial to allow for adequate energy for training and competition.


Training results in the breakdown of old muscle fibers; the body can then rebuild the muscles via a process called protein synthesis. This allows the body to become stronger and more efficient at performing the exercise. The rebuilding of damaged tissue relies on available nutrients. What and when you eat after exercise will affect your body’s recovery and, therefore, how well your body adapts to your training.

Dietary protein is key to providing the essential amino acids to promote protein synthesis. We have a 30 minute window period after exercise where protein synthesis is at its optimal. Providing a good quality protein source will help to stimulate protein synthesis and, therefore, training adaptions. Carbohydrate intake, together with protein, is also essential as it will also promote muscle rebuilding and will provide available energy for adaptions to occur.

After that, providing a continuous supply of protein throughout the day (at main meals and snacks) will help to ensure adequate nutrients are available for recovery.


During exercise, we lose most of our fluid through sweat. We also lose electrolytes, specifically sodium, potassium, and phosphorus. Fluid requirements are individual and vary according to the environment and the duration and intensity of the exercise.

Inadequate hydration can have a direct effect on performance. As your hydration declines, so your perception of fatigue increases, which will make exercising feel harder. If you become dehydrated, not only will it reduce your performance, but it could also potentially stop you from finishing your event. Dehydration occurs as a result of increased fluid loss without an adequate replacement.

Conversely, overhydration can also affect performance. Overhydration increases weigh and can lead to hyponatremia, which is a life-threatening condition. Overhydration occurs when there is excess fluid intake and a significant sodium deficit as a result of loss through sweat and inadequate replacement. This leads to an increase in total body water retention, which reduces blood sodium levels further.

Managing your hydration before, during, and after exercise is an essential component of ensuring optimal performance. Starting training or an event in a normally hydrated state will help prevent dehydration during exercise. Matching your fluid and electrolyte losses with your intake during exercise will further prevent dehydration and overhydration. After exercise, it is just as important to ensure that you replace any losses to assist recovery, provide adequate hydration for the next exercise session, as well as replace additional losses as you will continue to lose fluid post-exercise.


An important component to ensure optimal performance is making sure that your nutrition is tailored for your exercise. Having a good performance nutrition strategy can improve sports performance by ensuring that you are fuelled and hydrated before and during exercise and that you recover after exercise to support training adaptions and replace what was lost. Nutrition should always be a main consideration for anyone wanting to perform well in their sport.

Written by: Michelle Tolmay, Registered Dietitian, Kings Park Sports Medicine Centre.

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