2.1 Diet and Nutrition

Diet

Calories

• men aged 19-50 = 2500 calories per day

• women ages 19-50 = 2000 calories per day

Balanced Diet

• 55% carbohydrates

• 15% protein

• 30% fats

• 5 portions of fruit and veg

Components of a Diet

Carbohydrates

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

• preferred fuel for exercise - 75% of energy requirements

• Starches - rice, potatoes - stored as glycogen in the liver and muscles

• Sugars - fruit, honey - circulate in the blood stream as glucose

Proteins

• amino acids essential for the growth and repair of cells and tissues

• make muscle proteins - increases muscle size

• make haemoglobin

• make enzymes, antibodies, and collages

  • enzyme - biological catalyst which increases the speed of chemical reactions

• can also be used as a fuel when carbohydrates and fats are depleted

Fats

• triglycerides which provide the body with fatty acids for energy production

• insulate nerves, form cell membranes, cushion organs

• provide an energy store - broken down for aerobic energy production and have twice the yield of carbohydrates

• unsaturated - typically liquid at room temperature - help lower cholesterol

  • avocado, olive oil

  • can boost the delivery of oxygen, improve endurance recovery, reduce joint inflammation

• saturated - typically solid at room temperature - can be associated with CV disease

  • butter, bacon

  • intake should be limited to reduce the risk of cardiovascular disease

Vitamins and minerals

• essential organic an inorganic nutrients required for healthy body function

Minerals

• Calcium - bone health, muscle contraction, nerve transmission, blood clotting

• Iron - formation of haemoglobin, enzyme reactions, immune system

• Phosphorus - bone health, energy production

Vitamins

• A - antioxidant properties, eye health

• B - breakdown of food, haemoglobin formation, skin and eye health

• C - skin, blood vessels, soft tissues

• D - bone health, protection against cancer and heart disease

• E - antioxidant properties, skin and eye health

• K - blood clotting, bone health

Fibre and Water

• fibre is essential for the function of the large intestine - found in fruit, cereals, lentils, vegetables

• adequate fluid intake allows fibre to work properly

• water is essential for hydration - before, during, after exercise

• two-thirds of body weight is water

• dehydration can result in decreased plasma volume, decreased SV, increased temperature, and increased HR

Energy Intake

• energy = ability to perform work, measured in joules or calorie

• not enough calories:

  • atrophy

  • decreased intensity and duration of performance

  • increased risk of fatigue, injury, and illness

• energy expenditure = BMR + TEF + physical activity energy expenditure

  • BMR = minimum amount of energy required to sustain essential physiological function at rest - can be up to 75% of energy expenditure

  • TEF = energy required to eat, digest and absorb food

Energy balance

• relationship between energy intake and energy expenditure

• energy in < energy expenditure - weight loss

• energy in = energy expenditure - weight maintenance

• energy in > energy expenditure - weight gain

Ergogenic Aids

• substance, object, or method used to improve or enhance performance

  • nutritional aids - relate to diet and nutrition - all legal

  • pharmacological aids - increase levels of hormones or neural transmitters - all illegal

  • physiological aids - increase the rate of adaptation of the body

Pharmacological Aids

• Anabolic steroids

  • increases muscle mass and strength, increases recovery, increases intensity of training

  • irritability, mood, liver damage, heart failure

  • can treat muscle wastage diseases, used by weightlifters or sprinters

• Erythropoietin (EPO)

  • increases RBC count, increases O2 transport and aerobic capacity

  • increases blood viscosity, decreased cardiac output, increased risk of blood clots

  • difficult to detect - some athletes have naturally higher RBC levels, used by endurance athletes

• Human Growth Hormone (HGH)

  • increased muscle mass and strength, increased fat metabolism, increase blood glucose

  • abnormal bone and muscle development, enlarged organs, higher risk of cancer and diabetes

  • used by any type of athlete

Physiological Aids

• Blood doping - illegal

  • increased RBC level, increased O2 transport, increased intensity and duration

  • increased blood viscosity, decreased cardiac output, increased risk of blood clots, risk of infection

  • used by endurance athletes

• Intermittent Hypoxic Training (IHT) - legal

  • training under low oxygen conditions

  • allow for acclimatisation, increased RBC level, increased mitochondria and buffering capacity so delayed OBLA

  • benefits lost when training stops, can disrupt training patterns, decreased immune system function, dehydration

  • used by endurance athletes

• Cooling aids - legal

  • reduce core body temperature, decreased sweating and dehydration, decreased swelling and pain, decreased DOMS

  • difficult to perceive exercise intensity, can cause ice burns, can make injuries worse, dangerous for people with heart and BP issues

  • used by any athlete

Nutritional Aids

• Carbohydrate loading

  • day 1 intense exercise to deplete stores, day 2-3 high protein/ fat diet, day 4 intense exercise, day 5-7 high carbohydrate diet

  • increased glycogen stores, increased endurance, increased time to exhaustion, delays fatigue

  • can cause hypoglycaemia and poor recovery rates, gastrointestinal issues, can impact mental preparation

  • used by endurance athletes - ensures the is enough glycogen for aerobic glycolysis

• Pre-event meal

  • 3 hours before low GI (glycaemic index) food, 1-2 hours before high GI food

  • maintains liver glycogen, maintains blood glucose levels

  • can cause the body to counteract high glucose levels and cause the athlete to become dizzy/ fatigued

  • used by all athletes

• During event meal

  • maintains liver glycogen, maintains blood glucose levels

  • can be difficult to eat during activity, must be pre-planned

  • energy gel in a marathon, banana at the end of a set in tennis

• Post-event meal

  • carbohydrates ideally within 30 minutes of finishing, and then every 2 hours until 6 hours after

  • promotes faster recovery rates

  • not always practical or possible

  • used by all athletes

• Hypotonic drink

  • lower concentration of glucose than blood - prolonged exercise

• Isotonic drink

  • equal concentration of glucose to blood - events over 1 hour

• Hypertonic drink

  • higher concentration of glucose than blood - used during recovery, not exercise as it can increase dehydration

• Creatine Supplements

  • increases PC stores

  • more fuel for high intensity exercise, increased maximum and explosive strength

  • increased weight gain, muscle cramps and gastrointestinal issues

  • used by power athletes - weight lifters and sprinters

• Caffeine

  • stimulates the CNS

  • increased concentration, increased metabolism of fats, increased endurance performance - preservation of muscle glycogen

  • diuretic - dehydration, insomnia, anxiety, gastrointestinal issues

• Bicarbonate

  • neutralises a rise in acidity in the bloodstream

  • increased buffering capacity, increased tolerance to lactic acid, increased intensity and duration

  • gastrointestinal issues, unpleasant taste - nausea

• Nitrates

  • dilate blood vessels and reduce BP

  • decreased BP, increased blood flow, delays fatigue

  • headaches, dizziness, possible carcinogenic