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Many athletes, recreational and elite are aware of the need to properly hydrate to optimise training, recovery and competitive performance. This article examines the topic of hydration further and aims to provide athletes of all ages and abilities with an improved understanding of the need to develop an appropriate hydration plan to optimize your results and enjoyment of endurance sport.

The fatigue that many endurance athletes experience during training or competition is often related to factors such as glycogen depletion (the fuel needed for muscle activity), high training volumes, inadequate recovery including lack of sleep or race intensity.

An important, often underestimated and relatively ‘controllable’ component of performance optimization is adequate hydration, in training, recovery and competition.

Studies of exercise performance have shown that performance is effected by as little as a 2% reduction in body mass (1.4 kgs for a 70 kg person) and losses in excess of 5% of body mass can reduce your capacity to do ‘work’ (exercise) by approximately 30% (3.5 kgs for a 70 kgs person).

….’performance is effected by as little as a 2% reduction in body mass’….

When you combine this information with further data regarding average sweat rates of 1 to 1.5 litre/hour for sport the need to understand your own fluid needs is further strengthened.

So why does dehydration reduce athletic performance?

  1. It causes a decreased sweat rate, which alters your ability to regulate your body temperature. Given that increased muscle and cellular during activity generates ‘heat’, the ability to dissipate heat production is crucial for normal body function.
  2. It impairs mental function making decision making more challenging. Not great on challenging run courses!
  3. It impairs motor (muscle) function thereby effecting co-ordination and movement patterns making you more susceptible to overloading muscle, tendon, bone and fascia, potentially inducing injury.
  4. It increases the rate at which you use muscle glycogen
  5. It alters your blood volume and blood viscosity (thickness), which in turn negatively alters how hard your cardiovascular system, has to work to sustain activity.
  6. Dehydration can lead to gastric distress further impacting the ability to absorb or tolerate fluid intake.

TIP 1 Monitor your urine

Thirst is a poor indicator of hydration. It is best to develop a hydration plan for your day-to-day life. It is too late to start drinking fluids on the way to training or competition. The body needs a consistent fluid intake approach across the day. Monitoring your urine colour over your day can give you a guide to your hydration status (see chart). Please be aware that some medication, vitamins and foods can change the colour of your urine.

‘Thirst is a poor indicator of hydration’

TIP 2 Perform a basic ‘sweat test’

There are sophisticated and scientific ways of establishing sweat and electrolytes loss rates via tests conducted by an appropriately qualified health professional but most endurance athletes can improve their understanding of their individual requirements by conducting a 1-hour test as follows. (These tests are good to do at ‘race pace’ so as to simulate race intensity). It is also a good idea to note the temperature and humidity of the test day in your training diary.

  • First weigh yourself before you head out on your training run. It is best to do this in your ‘birthday suit’ so perhaps not the most appropriate thing to do at your weekly club run!
  • Perform your 1-hour session.
  • At the completion of your session immediately weigh yourself again naked before your go to the toilet.
  • If your pre session weight was 72.4 kgs and your post session weight was 71.2 kgs, you have a body mass loss of 1.2 kgs. It could be estimated that you have incurred an approximate loss of 1.2 litres off fluid giving you an understanding of your per hour fluid loss rate.

TIP 3 Electrolytes

Water is often not enough. There are many high quality electrolyte supplements available to athletes that can improve the manner in which the gastrointestinal system absorbs fluid. You are also replacing many of the minerals lost by the body through exercise such as sodium, potassium and magnesium. Do not trial a new supplement on race day! When possible carry electrolyte tablets that you have used in training and are comfortable with to avoid the negative effects of gastric distress.

‘Do not trial a new electrolyte supplement on race day’

TIP 4 Seek professional advice

If you remain unsure on the best way to develop a hydration plan for your individual needs please seek the assistance of an appropriately qualified accredited dietitian or high performance professional.

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