The body can store carbohydrates in the muscles and liver as glycogen to fuel exercise. Carbohydrate requirements are higher in intense and long duration exercise and regular intake is important to keep stores topped up.
Foods high in carbohydrate include low-fat milk and cereal, yoghurt, fruit, bread, pasta and cakes. Athletes may also need to consider consuming carbohydrate during exercise using energy gels or sports drinks.
Carbohydrates provide the body with a primary fuel source during intense exercise. Muscle glycogen depletion is a major contributor to fatigue and limits performance, particularly during prolonged exercise. It is therefore essential to maintain carbohydrate stores through a regular diet and to ingest sufficient carbohydrates during training and competition. In addition, it is important to replenish carbohydrates as quickly as possible after exercise through a carbohydrate-rich recovery meal or drink.
Both aerobic and anaerobic exercise decrease muscle glycogen, requiring high carbohydrate intakes to sustain endurance performance. Carbohydrate-rich foods and drinks are the best sources of carbohydrate and should comprise a majority of an athlete’s diet. Carbohydrates can also be ingested during exercise by consuming liquid carbohydrate products. The type of carbohydrate consumed is critical for optimizing performance, as it will impact the rate of carbohydrate oxidation and utilization.
Polysaccharides are large molecules consisting of many glucose units linked together and are the most common structural and energy-reserve carbohydrates found in nature. They include cellulose, starch, and glycogen found in plants and animals. Carbohydrate-rich beverages, such as fruit juices and sports drinks, can support the intake of polysaccharides during and after exercise. Glucose-fructose blends are preferred for within-event carbohydrate consumption during exercise, as they permit a greater range of metabolic responses than a single carbohydrate source. Pre-exercise carbohydrate ingestion is also beneficial and can be augmented by using an oral carbohydrate loading strategy.
Protein is an essential macronutrient that helps build and repair muscles, as well as other body tissues. It also makes up hormones, enzymes, red blood cells, and other substances that are important for normal body function. Proteins are made of chains of amino acids, nine of which are considered essential (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine) because the body cannot produce them and must get them from food.
Protein supplements are frequently used by athletes to increase protein intake and stimulate muscle protein synthesis after exercise. High-quality proteins include animal sources such as poultry, beef, dairy products and whole eggs and plant sources such as beans, peas and tofu. Athletes should try to consume these protein foods in the form of complete proteins that contain all the essential amino acids, particularly the branched-chain amino acids (BCAAs) such as leucine.
Ingestion of carbohydrate and protein (or EAAs) during prolonged bouts of endurance exercise increases rates of muscle protein synthesis, suppresses changes in markers of muscle damage, and may improve subjective feelings of muscular soreness. It is recommended that endurance athletes ingest 0.25 g of protein per kg of body weight to maximize MPS and promote recovery from exercise.
In addition, it is recommended that resistance-trained individuals ingest adequate amounts of protein to promote muscle growth and recovery from resistance training. Typically, this is achieved through whole foods such as poultry, fish, dairy products and whole eggs and by using protein powder supplements.
Fats are a major source of energy in the body and consist of carbon, hydrogen and oxygen atoms. They provide 9 calories per gram of fat, which is significantly more than carbohydrates and protein. Dietary fats are important for providing structure to cell membranes, insulating and protecting vital organs, regulating endocrine system function (how hormones are produced) and helping transport vitamins and minerals. Dietary fats also help with energy production and exercise performance. During exercise, fatty acids can be used as an alternative to carbohydrate fuel. This can be beneficial to an athlete as it may spare glycogen stores, reducing fatigue and allowing continued effort in the later stages of exercise (e.g. a distance runner).
Athletes should consume a diet rich in unsaturated fats, which are found mainly in olive oil, nuts and avocado. They should also include some saturated fats from whole foods, such as meat and dairy products, to obtain the essential omega-3 fatty acids.
Carbohydrate, protein and fat intake should be based on the duration, frequency and intensity of an athlete’s training and competition schedule. Carbohydrates should be consumed in a variety of foods and should be evenly spread throughout the day. Fats are slowly digested and are only used during low to moderate intensity exercise, so they should be included in meals away from exercise or in a pre-training snack e.g., a yoghurt with some nuts/seeds or an avocado.
Hydration is crucial for all athletes. When you fail to hydrate, your muscle function is compromised and your endurance decreases. This is because your body cannot make enough water on its own. It is recommended to consume 1/2 ounce of water per pound of body weight prior to exercise to prevent dehydration and to fuel your workout.
The RRCTFS survey demonstrated that many throwers are confused about the best fluids to drink during and after exercise. For example, over half of the respondents erroneously believed that thirst was the best indicator of dehydration. Also, they were not aware that consuming a sports drink within two hours of training improves the rate at which carbohydrate is restored to the muscles.
While water is the most preferred beverage for hydrating and replacing fluid lost during training sessions, it may not be sufficient to meet the needs of some athletes. Water alone does not replace the electrolytes (sodium and potassium) and carbohydrates that are lost when you sweat, which can lead to dehydration. During long-distance training sessions and intense competition, a mixture of water and carbohydrate-electrolyte drinks is recommended to avoid hyponatremia (an imbalance between sodium levels in the body and fluid).
The role of nutrition is to help you achieve optimal health and performance through proper food choices and eating patterns. Ensure that you are consuming adequate amounts of nutrients to keep you performing at your best, including carbohydrates, fats, and proteins.