Diet and nutrition

• Carbohydrates


  Sugars and starches stored in the body as glycogen and converted to glucose to fuel energy production
• Carbohydrates


  • An essential part of a person's diet for energy production, cell division, active transport and formation of molecules
  • They are the preferred fuel for exercise, accounting for approximately 75 per cent of energy requirements
  • Can be consumed in the form of starches (e.g. rice, potatoes) or sugars (e.g. fruit, honey)
• Glycogen and glucose


  Provide the fuel for aerobic and anaerobic energy production
• The best foods to consume are starches to maximise stores of glycogen, which are then broken down to maintain blood glucose levels
• Surplus glucose, associated with a high sugar diet, will be converted into triglycerides (body fat)
• Proteins


  Amino acids essential for the growth and repair of cells and tissues
• Proteins


  • Found in large quantities in milk, eggs, meat and soya
  • Can be broken down to provide energy aerobically if no other fuel is available
• Proteins are used to make muscle proteins, haemoglobin, enzymes, antibodies and collagen
• Fats


  Triglycerides which provide the body with fatty acids for energy production
• Fats


  • An important part of the diet, serving to insulate nerves, cell membranes, cushion organs and provide an energy store
  • Provide essential fatty acids and the fat-soluble vitamins A, D and E
  • Can be broken down for aerobic energy production and have twice the energy yield of carbohydrates
• Saturated fatty acids, such as butter and bacon, should be limited to reduce the risk of cardiovascular disease
• The majority of fat intake should be unsaturated fatty acids, such as avocado and soya beans
• Omega-3s (fish oil) may be particularly beneficial for athletes, boosting the delivery of oxygen, improving endurance and recovery rates, and reducing inflammation and joint stiffness
• Minerals


  Essential inorganic nutrients required in small quantities to maintain healthy body functions
• Minerals


  • Necessary for bone and tooth health, controlling body fluids, enzyme formation, breaking down food to release energy and normal nerve function
  • Essential minerals include calcium, iron, phosphorus, magnesium, sodium, potassium and chloride
• Trace minerals required in small quantities include zinc, iodine, fluoride, selenium and copper
• Vitamins


  Essential organic nutrients required in small quantities to maintain healthy body functions
• Vitamins


  • Fat-soluble vitamins (A, D, E, K) are stored in the body and found mainly in fatty foods and animal products
  • Water-soluble vitamins (C, B) are not stored and require regular intake, found in fruit, vegetables, grains, milk and dairy foods
• Even for performers undertaking intense exercise, there is no need for vitamin supplementation, providing sufficient energy is consumed through a varied, balanced diet
• Water accounts for two thirds of the body and is essential for hydration before, during and after competition, especially in hot climates like triathlon
• Dehydration can result in decreased performance and increased temperature and heart rate
• Components of a healthy diet

  • Carbohydrates
  • Fats
  • Protein
  • Vitamins
  • Minerals
  • Fibre
  • Water
• Carbohydrates


  Important component of a healthy diet, provide energy for nerves, form
• Fats


  Can also provide energy, essential for the increased delivery of oxygen to muscles and reducing inflammation
• Protein


  Essential for growth and repair of tissues, including muscle
• Water-soluble vitamins


  Not stored and require regular intake, found in fruit, vegetables, grains, milk and dairy foods
• Vitamin C


  • Important for skin, blood vessel, tendon, ligament and bone health
• Vitamin B


  • Important for the breakdown of food, haemoglobin formation and skin, eye and nervous system health
• The International Olympic Committee believes most athletes can meet their bodily needs for minerals and vitamins from a varied, healthy diet rather than from supplementation programmes
• Those on a restricted diet or when food choice is limited, such as during travel and competition in foreign countries, may need to supplement their diet, especially female athletes who have relatively low intakes of calcium, iron and vitamin D
• Dietary fibre


  Found in food such as cereals, bread, beans, lentils, fruit and vegetables, important for the normal function of the large intestine, can reduce cholesterol, risk of diabetes and obesity
• Water


  Accounts for two thirds of body weight, essential to allow chemical reactions and dissolve and move substances around the body, required for hydration before, during and after training and competition
• Dehydration


  Can result in decreased plasma volume, stroke volume and increased temperature and heart rate, leading to decreased endurance and strength
• Energy


  The ability to perform work (joules or calories)
• Energy expenditure


  The sum of basal metabolic rate, the thermic effect of food and the energy expended through physical activity
• Basal metabolic rate (BMR)


  The minimum amount of energy required to sustain essential physiological function at rest, which can account for as much as 75 per cent of total energy expenditure
• Thermic effect of food (TEF)


  The energy required to eat, digest, absorb and use food taken in, which accounts for a very small percentage of the total energy expenditure
• Physical activity energy expenditure

  The total number of calories required to perform daily tasks, which can be estimated using MET values
• Metabolic equivalent (MET) value

  The ratio of a performer's working metabolic rate to their resting metabolic rate
• Energy intake is the total amount of energy from food and beverages consumed and measured in joules or calories