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Carbohydrates: Ultimate Energy Source for Endurance Sports

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Carbohydrates: Ultimate Energy Source for Endurance Sports

Carbohydrates are the body’s main source of energy and should make up around 1/3 of your diet (10). There are three different types of carbohydrates; sugar, starch and fibre. Starch is the key carb to consume as it provides a slow release of energy throughout the day. Starch can be found in many foods such as bread, rice, potatoes and pasta.

Many popular diets advise cutting out carbs from your diet to lose weight, as the body breaks down stored fat instead of the glucose, which comes from carbs, to turn into energy. However, this increases ketones in blood, causing ketosis, and decreases sugar levels in the blood, causing hypoglycemia. These conditions can result in headaches, weakness, nausea, dehydration, dizziness and irritability (9).

During exercise, your body relies on your glycogen stores in your muscles which can quickly run out during high intensity endurance sports. Depletion in glycogen can result in tiredness and a lack of energy. Topping up on your carbs during exercise through gels, chews, bars and drink mixes can prevent energy levels from dropping mid-exercise.

The recommended carbohydrate intake for endurance athletes is 6-10g per kg body weight, per day so an athlete weighing 70kg should consume 420-700g of carbs during one day (1).


It increases energy & prevents fatigue:

When carbohydrates are ingested, the body will convert them into glucose which is used as a fuel to provide you with energy. During exercise, your energy source comes from the glycogen stores in your muscles (6) which can cause tiredness and fatigue when the level of glycogen drops. In one study, carbohydrate supplementation was shown to reduce muscle glycogen depletion, thus increasing energy levels and delaying fatigue (4).

Carbohydrate-electrolyte drinks can increase your endurance performance as well as improve lactate removal which in turn prevents fatigue (8). Ideally carbohydrates should be taken during exercise at a rate of 30-60g per hour, in a portable solution form such as a drink or gel which also contains glucose, sucrose or maltodextrins (5). Most energy gels luckily come in sizes from 30-60g making them perfect for carbohydrate consumption on the go. Consuming carbohydrates during moderate intensity exercise has shown to prevent fatigue by up to 30 minutes (4).

Improves performance:

Studies have shown that during high intensity exercise lasting over 2 hours, consuming carbohydrates can significantly improve endurance performance. Even for athletes involved in team sports such as football, rugby, tennis, cricket and netball, carbohydrate ingestion has shown to greatly benefit their performance (2).

For athletes taking part in exercise lasting 2 to 3 hours, it is advised to consume 60g of carbohydrates an hour, to maximise oxygen glucose oxidation rates in the blood which helps with metabolism. While well-trained endurance athletes completing races longer than 2.5 hours can consume up to 90g of carbohydrates an hour, providing it is taken in several smaller servings such as energy gels (2).

It prevents Hypoglycemia:

Hypoglycaemia is the drop in blood sugar levels that usually occurs after the body produces too much insulin. Symptoms of low blood sugar includes dizziness, tiredness, feeling shaky or trembling, heart palpitations, and if left untreated can lead to confusion, sleepiness, passing out, and even seizures or fits (9). Carbohydrates can prevent and greatly reduce the risk of getting hypoglycaemia (11), and be can be taken through carbohydrate snacks such as toast, or through carbohydrate drink mixes like the Maurten Drink Mix.

If during exercise you notice your blood sugar levels dropping, ingesting energy gels or energy drink mixes with carbohydrates in, can help prevent the post-exercise shakes. Gels with slow-release carbs like the Muir Energy Gel or OTE Super Gels, are great for boosting energy and are easy to take on the go.

Reduces the risk of heart disease:

When losing weight, many diets will advise cutting out carbohydrates from your diet altogether, however this comes with risks. In these diets, carbohydrates are typically replaced with fats or proteins with high fat contents, which will cause your body to use stored fats for fuel instead of the glucose you get from carbs. However, by increasing your intake of saturated fats, you are also raising the cholesterol found in your blood. The high saturated fat and high cholesterol levels can lead to heart disease or strokes (10).

These high fat, low carb diets have shown to provide short-term solutions for many people in losing weight, while being more beneficial in people with diabetes looking to reduce insulin levels (3).

Consuming carbohydrates as your source energy instead of fat will decrease your risk of heart disease. Eating a balanced diet of 1/3 carbohydrates, 1/3 fruits and vegetables and 1/3 dairy and protein, staying active and reducing sugar consumption will also help prevent heart disease (10). Eating a plant-based diet with a carbohydrate base, there is a significantly lower chance of developing heart disease, diabetes and obesity (3).

Aids in repair & recovery:

The two hours after exercise are the most important hours during the recovery process. Rebuilding glycogen levels and replenishing electrolytes are most effectively done during this “opportunity window” (7) and helps increase recovery time. Post-exercise is the best time to consume a meal or snack filled with carbs such as bread, pasta, rice, lentils, beans and potatoes.

It is essential to remember that carbohydrate intake will differ from person-to-person depending on gender, age, weight, exercise intensity, length of time exercising, and current diet.


(1) British Nutrition Foundation, 2020. Nutrition for sports and exercise. Available at: (Accessed: 26th May 2021).

(2) Cermak, N.M. and van Loon, L.J., 2013. The use of carbohydrates during exercise as an ergogenic aid. Sports Medicine, 43(11), pp.1139-1155.

(3) Connor, W.E., Duell, P.B. and Connor, S.L., 2005. Benefits and hazards of dietary carbohydrate. Current atherosclerosis reports, 7(6), pp.428-434.

(4) Coyle, E.F. and Coggan, A.R., 1984. Effectiveness of carbohydrate feeding in delaying fatigue during prolonged exercise. Sports Medicine, 1(6), pp.446-458.

(5) Coyle, E.F., 1991. Timing and method of increased carbohydrate intake to cope with heavy training, competition and recovery. Journal of Sports Sciences, 9(S1), pp.29-52.

(6) Gollnick, P.D. and Matoba, H., 1984. Role of carbohydrate in exercise. Clinics in sports medicine, 3(3), pp.583-593.

(7) Haff, G.G., Lehmkuhl, M.J., McCoy, L.B. and Stone, M.H., 2003. Carbohydrate supplementation and resistance training. The Journal of Strength & Conditioning Research, 17(1), pp.187-196.

(8) Khanna, G.L. and Manna, I., 2005. Supplementary effect of carbohydrate-electrolyte drink on sports performance, lactate removal & cardiovascular response of athletes. Indian Journal of Medical Research, 121(5), p.665.

(9) National Health Service, 2020. Low blood sugar (hypoglycaemia). Available at: (Accessed: 27th May 2021).

(10) National Health Service 2020. The truth about carbs. Available at: (Accessed: 26th May 2021).

(11) Rodriguez, N.R., Di Marco, N.M. and Langley, S., 2009. American College of Sports Medicine position stand. Nutrition and athletic performance. Medicine and science in sports and exercise, 41(3), pp.709-731.

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