Hydration (AQA GCSE Physical Education (PE)): Revision Note

Reasons for Maintaining Water Balance

• Dehydration is the excessive loss of body water, interrupting the functioning of the body

• It occurs when the body does not take in enough water to supply the needs of the body's metabolism and to resupply the water that is lost via excretion (e.g. sweat)

• Consuming water in food and drinks (hydrating) is essential for preventing dehydration

  • This is particularly important during exercise when increased sweat is lost to the environment

• There are several consequences of prolonged dehydration. These include:

  • The slowing down of blood flow due to 'thicker' blood with high viscosity. This reduces the delivery of essential chemicals like glucose and oxygen to the cells

  • Heart rate increases 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 can easily overheat

  • The reduction in blood flow to the brain and muscles can also increase reaction times and lead to poor decision-making

    • This can have a particular impact on sporting ability and success in competitive environments

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