Hydration for physical activity

Hydration means replacing lost fluid

Hydration means having enough fluid in the body. Drinks contribute to fluid intake, and some fluid also comes from food. If a person does not take in enough fluid to replace what they lose, they can become dehydrated.

Water has several important roles: it helps transport nutrients in the blood, remove waste through urine and regulate body temperature. A performer therefore needs to consider fluid intake alongside the demands of their activity, rather than treating drinking as something unrelated to exercise.

Sweating cools the body but loses fluid

During exercise, the body produces heat. Sweating helps control body temperature because sweat removes heat as it evaporates from the skin. However, sweating also means that water is leaving the body.

Drinking replaces this lost fluid. Without enough replacement, dehydration makes it harder for the body to regulate its temperature. Body temperature and heart rate may rise excessively, increasing the strain on the performer. This is particularly important during exercise in hot conditions, when dehydration can make performance worse and increase the risk of heat stress.

Hydration supports physical and mental performance

Dehydration can cause greater fatigue, reducing a performer’s ability to sustain effort. For example, a distance runner may find it harder to maintain their pace. Maintaining hydration supports endurance by helping the body function effectively throughout the activity.

It can also reduce concentration, decision-making and control of movement, and slow reaction times. These effects matter even in sports that are not continuous endurance events. A dehydrated netball player, for example, may react more slowly to an opponent’s movement or make a poor decision about where to pass.

Correct hydration therefore supports both physical effort and skilful performance. It is not just about avoiding thirst: it helps a performer stay alert, maintain effort and control body temperature.

Fluid needs change with the conditions

The general daily recommendation is 6–8 cups or glasses of fluid, but this is a guide, not a fixed target for every person or every training session. People may need more fluid when they are physically active for long periods or are in a hot environment.

Exercise intensity, duration and how heavily someone sweats also affect their needs. For example, someone taking part in a long training session on a hot day needs to account for these conditions when planning access to drinks. Their usual daily intake may not be enough to replace the additional fluid lost through sweating.

Maintaining hydration around exercise

The practical approach is to drink regularly throughout the day and take extra fluid when sweating through physical activity. This means building hydration into the routine before, during and after exercise, rather than relying on a single drink at the end.

Before exercise, regular drinking helps the performer begin well hydrated. During a prolonged activity, having water available at suitable breaks makes drinking little and often possible. A football player could use stoppages and half-time to drink; a runner needs to plan access to water along their route.

Afterwards, continued drinking helps replace fluid lost during the activity. Fluid can still be lost through sweating and urine after exercise finishes, so recovery involves more than one immediate drink. The amount needed depends on the circumstances; there is no single total that suits all exercise sessions. Drinking excessive amounts is also unsafe, so the aim is to replace losses, not to drink as much as possible.

Water is a healthy, inexpensive choice and is suitable during and after most activities. Other drinks can contribute to daily fluid intake, but regularly choosing high-sugar drinks adds sugar and can damage teeth. Sports drinks containing carbohydrates and electrolytes may be useful during prolonged, strenuous exercise, but are not necessary simply because someone has exercised.

Checking hydration

A useful everyday guide is for urine to be a clear, pale yellow colour. Darker urine can indicate that more fluid is needed. Thirst is another signal, but it should not be the only guide: feeling less thirsty after drinking does not necessarily mean all lost fluid has been replaced.

Regular drinking, checking urine colour and taking account of activity and heat work together. The key connection is: exercise produces heat, evaporating sweat helps cool the body, sweating loses fluid, and replacing that fluid helps maintain health and performance.