Nutrition for endurance sports

When partaking in endurance sports, we need to ensure we have the following boxes ticked:

  • ensuring hydration
  • providing adequate energy
  • sustaining motivation
  • recovering from training and competition

Ensuring hydration

Normally, the first limiting factor in endurance sports is hydration, especially in hot weather. We need to take on board enough water to keep our muscles, joints, and brain all working optimally. When we are dehydrated and have lost more than around 4% of our body weight (2.4kg for a 60kg woman), our performance rapidly drops. Even if you have not lost that much water, it has been found that having a dry mouth can reduce performance, and so just regularly sipping a drink can make quite a difference.

Sweat rate and respiration rate

Every individual has different hydration needs that depend on their sweat rate and respiration rate. For instance, your sweat rate, although unique to you, will increase as temperature, wind speed, and humidity rise. Your respiration rate will rise the harder you are working. As the water losses mount, you need to start replacing the fluid at a rate that lets you finish your exercise without a drop in performance level.

How much should I drink and when?

Start sipping a drink after around 30 minutes of exercise to prevent your mouth drying out, especially in hot and windy conditions. You do not need to finish at the same weight that you started out - in fact, that would be counterproductive for most people, leaving them at risk of over-drinking and possibly hyponatraemia (collapse due to deficient salt levels). Finishing an endurance event around 2-4kg lighter than when you started is acceptable for most. In fact, one legendary endurance runner lost 10% of his body weight while winning the 2009 Dubai marathon in a very fast time. However, 10% weight loss is not an appropriate guideline for most people!

Providing adequate energy

As you exercise, you burn up two types of fuel. Glucose is the quickest burning fuel that allows you to make maximal efforts. Fat is a slower burning fuel that is better suited to endurance. However, all endurance athletes will burn a proportion of both, with more fat predominating the longer they go on.

Glucose is stored as glycogen in your muscles and liver. The amount of pure glucose in the form of glycogen that you have stored is limited and may cover between one-two hours of maximal activity. That is why many marathon runners hit a wall after the halfway mark, having burnt all their glucose reserves. Using predominantly fat, they are unable to run as fast as before.

Reserves of fat are stored throughout your body and can last for days. It is only in ultra distance events that the need to consume fats and proteins to maintain body mass kicks in.

How much energy should I eat and drink, and when?

If you are just training, it can be useful to go without energy as a means to encourage your body to become more efficient at burning fuel. This is called "training low". For instance, a one hour run or cycle without any energy should be possible for most athletes. Running, cycling or swimming for two to three hours without any fuel can be more difficult, but is possible with practice, and is also a sign that your blood sugar handling is improving. This is also a signal that your diabetes risk is very low. This sort of training is best done once or twice a week and is only really relevant if you are exercising for more than 90 minutes.

However, it would be silly to restrict energy when you are competing or training at your limit. In these cases, you need to start taking on energy as soon as 20 minutes after starting exercise, and feed around every 10 minutes while cycling or every 20 minutes while running. The amounts needed vary depending on your size, performance, and effort level, as well as how long the event is. Longer events require more energy, and the feeding plan becomes more important the further you go.

The weight factor

With some sports such as running, cross country skiing and cycling, your weight is an important factor determining your performance level. Skipping a large breakfast before a short event that lasts less than 90 minutes can be a helpful tactic. Reducing weight by as much as 1kg can increase your running speed by as much as 10 seconds per mile.

Sustaining motivation

An often overlooked aspect of performance is the mind, and nutrition does play an important part in sustaining motivation. Avoiding episodes of hypoglycaemia (low blood sugar) is the most important, as hypoglycaemia drains motivation quickly. In a similar fashion, caffeine is able to reduce your perception of effort while at the same time releasing glucose into your blood. This is the reason there are so many sports products with added caffeine.

Recovery from training and competition

Recovery is absolutely vital if continued improvements are to be made, and without it, you can almost guarantee that your performance levels will at best plateau, and more usually drop.

The best strategy is to eat a rounded meal as soon after completing exercise as you can. This meal should contain carbohydrates, fats, and protein, as you will need all these components of food to make a proper recovery.

  • Carbohydrates can be of any sort, as this is the time when a quickly absorbed carbohydrate such as pasta, rice, bread, and cakes are not stored as fat, but rather get converted into glycogen and stored in your muscles.
  • Fats and cholesterol are required for the immune system and to restore cell membranes that are damaged by the intensity of long arduous endurance efforts.
  • Protein is required to help muscle recovery and repair other parts of the body after exercise.


When performing endurance exercise over more than 90 minutes, nutrition and hydration are very important factors. Practice with different drinks and food to check they do not upset your stomach. Remember also that you can use homemade snacks and drinks, which are often healthier and more environmentally friendly than commercial sports nutrition products.

The views expressed in this article are those of the author. All articles published on Nutritionist Resource are reviewed by our editorial team.

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Milton Keynes, Buckinghamshire, MK16
Written by Robin Dowswell, BSc MFNTP
Milton Keynes, Buckinghamshire, MK16

Robin Dowswell is a nutritional therapist working just outside Milton Keynes. He specialises in nutrition for health as well as sports nutrition. Check out his nutrition A-Z to find out about over 50 different foods and supplements as well as information on diets for a range of conditions.

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