Nutrition & Sport (OCR GCSE Physical Education (PE)): Revision Note

Diet & hydration relating to sport

• A balanced diet is the starting point for most people but sports performers, especially those at elite level, need to plan their nutritional intake ensuring: 

  • the timing of meals fits around their training and events schedule 

  • their diet is balanced 

  • they have adequate fluid intake 

  • their diet is suitable to their workload 

• To get glucose into the body it must be consumed in the food we eat  

• Energy is measured in calories and has the unit Kcal  

• Different sports performers will have different day-to-day energy requirements. This varies depending on factors such as:  

  • Age:  

    • Young children require a lot of energy because they are very active and use energy for growing  

    • Adults require less energy because as you age, your body loses muscle mass and gains fat. Fat burns fewer calories 

  • Gender:  

    • Males tend to need more calories than females 

    • The average adult male requires 2,500 Kcal/day  

    • The average adult female requires 2,000 Kcal/day  

    • When athletes are training intensively this may increase to around 5,000 calories a day

  • Height:  

    • Taller people require more energy than shorter people because they have more body cells that are respiring  

  • Lifestyle:  

    • Exercise burns calories  

    • The more exercise a person carries out, the higher the energy requirement  

    • People who live a sedentary lifestyle require very little 

Effective nutritional strategies 

• Ensuring the body has enough glycogen is crucial for optimum energy supply 

• One method of increasing glycogen stores is known as carbohydrate loading  

  • This is a technique involves the athlete depleting their stores of glycogen by cutting down on carbohydrates and keeping a diet of protein of protein and fat for three days 

  • For the three days leading up to the event, the performer lightly trains with a high-carbohydrate diet 

  • Performers such as distance runners and cyclists, triathletes and cross-country skiers use this technique as it helps to offset fatigue 

Hydration and exercise 

• When we exercise, our body sweats in a bid to cool itself down and we lose water and salts

• Genetics, the clothing we wear, the amount and intensity of exercise we are doing and the temperature of our surroundings all contribute to how much we each sweat 

  • It is estimated that on average between 0.5 to 2 litres of sweat are produced per hour of exercise 

• If we do not replace lost fluids then we can experience dehydration which is the excessive loss of body water, which disrupts the normal body functions 

• Prolonged dehydration can lead to: 

  • The slowing down of blood flow due to 'thicker' blood with increased viscosity, meaning less oxygen is supplied to the working muscles and to the brain. 

    • It also means that waste products such as CO2 and lactic acid cannot be removed as efficiently 

  • An increase in heart rate to try and counteract the effect of the slow-flowing blood

  • Sweating is a very important mechanism for cooling the body down. Without excess water for sweat, the body could increase in temperature (overheating) causing dizziness or fainting. 

    • This could prevent a performer from continuing their training or activity 

  • Reaction times slow down as the brain is receiving less oxygen and muscles get tired 

    • This can result in poor decision making and reduced skill levels 

  • Muscle fatigue and cramps are also common symptoms of dehydration due to a lack of oxygen due to slow blood flow 

    • The muscles will tire, causing cramp and a limited range of movement which could potentially force the performer to stop continuing in their event