Hydration strategies and sports drinks

Overview

The effects of dehydration, hydrating before, during and after exercise with worked fluid figures, monitoring hydration, thirst in the heat, isotonic, hypotonic and hypertonic drinks, and the danger of too much plain water.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   What are the main effects of dehydration on sporting performance?

   Model answer

   Dehydration raises heart rate and body temperature, so exercise feels harder and endurance falls. Concentration and skill also decline, and the risk of heat illness rises.

2. 2

   How should a performer hydrate before exercise?

   Model answer

   A common guideline is about 500 ml of fluid two to three hours before exercise. A further 200 to 300 ml can be taken 10 to 20 minutes before the start.

3. 3

   How should a performer hydrate during exercise?

   Model answer

   The performer should drink little and often, such as 200 to 300 ml every 10 to 20 minutes. Intake should be matched to sweat rate rather than forced.

4. 4

   How much fluid should be drunk after exercise?

   Model answer

   Roughly 1.5 litres should be drunk for every kilogram of body mass lost. The extra 50% allows for fluid still being lost in urine and sweat.

5. 5

   A rower weighs 1.2 kg less after a training session. How much fluid should be drunk to rehydrate?

   Model answer

   The rower should drink about 1.8 litres. The working is 1.2 kg × 1.5 L per kg = 1.8 L.

6. 6

   A runner's mass falls from 75.0 kg to 73.8 kg during a one-hour run, and 0.5 L of fluid was drunk. What was the sweat loss?

   Model answer

   The sweat loss was about 1.7 litres in the hour. The working is 1.2 kg + 0.5 L = 1.7 L, since 1 kg of sweat is about 1 L.

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.