SPORTS NUTRITION
Milk is a natural source of many valuable nutrients which have important roles for sports people. Milk provides natural carbohydrate (lactose) to supply energy; calcium, protein and phosphorus for normal bone health; protein for the growth and maintenance of muscles; iodine, vitamin B12 and riboflavin to support energy release; as well as being packaged in a fluid form with natural electrolytes to support hydration. Milk is an affordable and widely accessible beverage choice, as it is a common commodity in most home fridges and available in every local shop nationwide. Milk is also considered by many sports people as a convenient and versatile recovery drink which can be consumed as a stand-alone drink, or blended with fresh fruit to create a post-exercise smoothie.
Adequate recovery following intense exercise is essential in order to perform well in subsequent training sessions, a match or competition. Milk is considered by many as a natural, convenient, accessible and affordable drink to consume post-exercise in order to address the key considerations of recovery: 1) REFUEL: Milk contains a natural carbohydrate (lactose) which assists in refuelling energy stores 2) REPAIR: Milk provides high quality protein (casein and whey) which contributes to muscle growth and repair 3) REHYDRATE: Milk contains natural electrolytes (e.g. potassium) and is packaged as a fluid (approx. 87 % water) to aid rehydration.
For effective rehydration, fluid intake should replace sweat losses. Electrolyte-containing fluids ensure greater retention of fluids in the body. Milk and liquid dairy foods provide the body with a great source of water and electrolytes. The sodium concentration of milk is similar to that of other sports drinks, with several studies showing that it is equally effective (or even better) than sports drink or water for rehydration. Milk also contains additional electrolytes, e.g. potassium that will assist in fluid absorption.
Intense exercise results in muscle tissue undergoing repair and adaption to enhance function. Taking 20 to 25 gram of a high quality protein after resistance exercise, high-intensity interval training and endurance events contribute to muscle repair and adaptation. Dairy protein has been found to be superior to other protein sources in optimising muscle protein synthesis following resistance training. Milk protein provides all of the essential amino acids, specifically leucine, which is recognised for its role in muscle protein synthesis. Emerging research is suggesting a volume of 500 mL of low-fat milk post-exercise as effective to assist muscle recovery.
Muscle protein anabolism implies that muscle protein synthesis must exceed muscle protein breakdown. Building muscle requires sufficient stimulation e.g. resistance exercise; as well as a healthy, balanced diet that provides adequate energy and muscle-friendly nutrients such as protein. Milk can play a role in building muscle as it is rich in high quality protein – providing all of the essential amino acids (building blocks of protein) our body needs. Milk protein consists of 80 % casein and 20 % whey. Whey is particularly high in the amino acid leucine which is recognised for its role in rebuilding muscle protein. Emerging research is demonstrating the consumption of milk following resistance exercise as an effective option for stimulating muscle growth in both men and women.
Low-fat chocolate milk has been highlighted as a popular option among sports people post-exercise. This is because chocolate milk provides important nutrients which address the key considerations of post-exercise recovery 1) REFUEL: Chocolate milk contains a natural carbohydrate (lactose) as well as added sugars such as glucose and sucrose which assist in refuelling energy stores 2) REPAIR: Chocolate milk provides high quality protein (casein and whey) to stimulate muscle growth and repair 3) REHYDRATE: Chocolate milk contains natural electrolytes (e.g. potassium) and is packaged in a fluid (approx. 83% water) to aid rehydration. Chocolate milk is also considered a palatable option after exercise as well as being a convenient, accessible and relatively affordable recovery choice. Due to its added sugar and therefore increased carbohydrate content in comparison to plain milk, choosing chocolate milk post-exercise is best following an intense exercise sessions and as part of a healthy, balanced diet.
Generally, all of the energy and nutrients we need can be provided by a healthy, balanced diet – with no need for supplement use unless a deficiency is identified. Athletes with a high protein need can fulfil the need with protein-rich food sources such as dairy products, meat, fish, eggs and soy. The intake of supplemental protein when the diet is already sufficient in protein will probably pose no additional benefit for the athlete. There is also little evidence to support the benefit of supplementing with individual amino acids when athletes are consuming an adequate diet. Some athletes although find it difficult to consume protein food sources at the ideal time and a protein supplement may add some convenience. Athletes should although be aware of protein supplements that contain extra ingredients and impurities.
Generally, ‘protein milk’ contains additional milk protein (which is 80 % casein and 20% whey) and this increases the protein content from approximately 3.5% in plain milk to 5% in protein milk. Apart from this, ‘protein milk’ reflects a similar nutrient profile to plain milk, unless other additional ingredients are added such as flavours (these will be stated in the ingredients list). Protein supplements, which usually are in powdered form, can be varied with many varieties on the market. Those providing milk protein may be either casein or whey isolate which provide only the specified protein constituent; or casein or whey concentrate which may include additional ingredients.