Module 4 - Hydration and Sports Performance

Table of Contents

1. Hydration and sport: Signs and symptoms
   1. Hypohydration or Dehydration
   2. Hyperhydration or hyponatremia
   3. Superhydration
2. Hydration and Sport: Fluid intake for performance
   1. Fluid intake before competition
   2. Fluid intake during competition
   3. Fluid intake after competition
3. Hydration and Sport: Choose the right fluid
   1. Water
   2. Hypotonic sports drinks
   3. Hypertonic sports drinks
   4. Isotonic drinks
   5. Sports drinks dilution activity
4. Hydration and Sport: Best practice for performance

Hypohydration or Dehydration

The loss of a large volume of body fluid because of heat, exercise or illness is known as Hypohydration or Dehydration. It can have serious consequences for any person even if they are only slightly dehydrated - if an sports performer loses even 5% of their body weight through fluid loss, there will be a significant decrease in performance of up to 30%.

Dehydration occurs when fluid losses are not properly replaced by fluid intake. This is especially a problem during exercise and hot conditions, because the body naturally controls temperature by sweating. Hypohydration can cause many symptoms including tiredness and poor concentration, headaches, nausea and cramps. Exercising in a dehydrated state can make some individuals more susceptible to minor injuries as well.

A sports performer might expect to rely on thirst as a good indicator that they need to drink, but unfortunately the thirst mechanism relies on signals from the body that are relayed when a person is already dehydrated. This is known as a negative feedback system, and effectively means that when a person is thirsty, they might have already missed the opportunity to avoid hypohydration.

One way of checking that a person is dehydrated is to monitor urine colour. If there is lots of Pale urine, this is a good indication that a person is drinking enough. The urine should normally be a pale straw yellow colour. If urine is dark yellow, this indicates dehydration.

Hypohydration can occur for a number of reasons, including:

How much activity a sports performer does during their day. The more activity, the more important it is to constantly maintain hydration levels.

The intensity of the activity - the higher the intensity, the more fluid is lost to ensure that body temperature is maintained within normal limits.

The length of time of the activity - the longer the activity, the more fluid is lost. This is especially true where sports are played over a set period of time with no opportunity to rehydrate, such as football or rugby.

Specificity of the activity - sometimes, the venue for the sport might cause fluid loss. An example might be a squash court and so it would be good practice for a sports performer to include regular opportunities for fluid replacement wherever possible.