The Athletes Diet

Sports vary widely in the demands made upon the body. The standard of elite performance leaves little margin between victory/defeat. The search for improvement in performance will continue. An elite performer can meet all their nutritional needs from a ‘normal diet’ The use of high tech food supplements and drinks by elite performers significantly improves performance.

Optimal Weight…..? Excess weight means more energy required by the elite performer – so there is said to be an ‘optimal weight’ for different sports. Our bodies are made up of many tissues, the ones we can most easily manipulate are our MUSCLE MASS and FAT. Fat is still vital for providing energy for low-intensity endurance events, insulation against the cold and protection of internal organs Certain sports rely heavily on ‘power to weight ratio’ for the performer. This can have both a positive and negative effect. Simple measure of a healthy body weight, is your BMI. 27 and over = greater risk of health problems 27 and under = less risk, although too low can lead to problems

Importance of Water Water is vital for the elite performer because: –Regulates body temp –Carries nutrients and oxygen to all cells, via blood plasma –Assists with the conversion of food into energy and absorbs nutrients –Required for expiration –Removes waste –Protects and cushions vital organs and joints The body has a wide range of electrolytes that are vital for the functioning of cells – muscular

What are Electrolytes? They are electrically charged particles (ions) of salts such as Sodium/potassium/chlorine The body has a wide range of electrolytes that are vital for: – the functioning of cells – muscular; –ensuring nutrients and waste are exchanged –Ensuring the body’s pH level is maintained. S/P/C are vital for electrical transmission of nerve impulses that control muscle contraction A deficiency in one can alter the overall concentrations within the body – affecting performance.

Effects of Electrolytic Loss Electrolytic balance is affected by electrolyte loss through sweating and through an unbalanced diet The liver filters out excess electrolytes caused by diet imbalances such as too much salt Loss of electrolyteseffect on performance Impaired decision making Muscle weakness and fatigue Muscle cramps Interference of neural control of heart causing abnormal heart rhythm Electrolytes dissolve in water – so any changes in amount of water in the body, directly affects the electrolyte balance

Maintaining water/electrolytic balance (Temp reg during ex – Cyclist – p45) This must be in relation to: Intensity/duration of exercise Environmental conditions Convenience of ingesting fluids and electrolytes How to maintain balance: Water on its own – causes bloating/surpresses thirst/stimulates more water loss through urine output – which affect sodium levels More effective to consume drinks that contain electrolytes AND carbs. Easily absorbed into blood supply Concentrates of Carbs, Elect and water are dependant on: B.weight/Intensity/Duration/Temp/Humid/Level of Fit

Dehydration/Electrolyte Loss Amount of water lost varies in relation to environmental conditions: Temp/humidity/altitude as well as the intensity of exercise. Amount of water lost from exhaling can vary – ¼ - 1/3 Water loss is greatest in cold temps – inhaled air is dry or when at altitude Water loss when sweating – greatest during high temp. Sweating forming on the skin does not evaporate, therefore the body can not easily cool itself Heat = by product of exercise. The body must lose heat to maintain internal temp.

Exercise increases breathing rate – water vapour lost through increased exhaling Sweating loses electrolytes Leads to dehydration Dehydration Blood plasma has high proportion of bodys’ water Blood thickens Reduction of blood flow Raise in cardiac activity to maintain flow to organs/muscles As blood volume decreases, blood flow to skin reduces and body can not cool itself effectively Body temp rises Rise in core body temp

Preventative measures: Fluid loss which exceeds 3-5% of body weight: Reduces aerobic exercise performance Impairs reaction time/judgement Reduces concentration/decision making Therefore, measures should be taken before, during and after exercise to prevent dehydration/loss of electrolytes: BEFORE: Remain hydrated on the way to an event Not necessary for electrolyte drinks (provided balanced diet has been followed) ml fluid, 2/3 hrs before ex ml – 15 mins before ex Meal/Snack high in carbs 2-4 hrs prior to event

During: Ex can prevent you from feeling thirsty – therefore you should ingest water whenever possible You should be aware of the “Glycaemic Index” – a ranking system depending on how quickly carbs are converted to glucose and enter the bloodstream – raising blood sugar levels High GI can be absorbed rapidly by the body/Low GI much slower rate Athletes choice of carbs depends on whether they want rapid restoration of blood sugar levels after prolonged work, or a slower release of glucose into the blood stream Small amounts of H/L GI’s - avoids peaks and troughs

After: Endurance athletes exercising in humid conditions – find it particularly difficult to remain completely hydrated – because: Exercise represses thirst – underestimation of dehydration Limited opportunities to rehydrate Intolerance to taking on board too much fluid Underestimate how much athlete is sweating Rehydration after is vital especially if athlete is to continue exercising later/next day Essentially athlete is aiming to restore water/electrolyte balance Replenish carbohydrates Immediately after exercise – electrolytic drink would help, but should consume usual diet – naturally containing plenty of fluids/carbs