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Tim Matthews is a freelance fitness and nutrition coach and Naish sails opinion leader. He has recently been working with several PWA competitors, most notably John Skye, to help them achieve their optimum levels of performance. Tim also runs fluidforce – a company specialising in supplying leading sports nutritional advice and products at market leading prices.

Tim Matthews - Fitness Coach

Age:	31yrs
Local Beach:	Shoreham, West Wittering
Email:	Tim@fluidforce.co.uk
Website:	www.fluidforce.co.uk

Dehydration and Performance

When we windsurf water is all around us. It is the element that allows us to do the sport we love BUT as this article will show it is not the water on the outside that we have to worry about but the water (or lack of it) on the inside.

What is it?

Dehydration is the loss of fluid from the body. Studies have shown that performance can reduce by up to 33% as a result of dehydration. (British Journal of Sports Science. 1998)

Dehydration also causes the loss of minerals and electrolytes (calcium, magnesium, sodium, potassium and chloride) from the body that assist in maintaining effective bodily function.

Was Dunky suffering from dehydration at the recent PWA Fuerte Slalom event?

How does it occur?

Dehydration occurs as the body’s temperature increases during exercise. The body combats this increase in temperature by producing sweat as a cooling mechanism. This has the side effect of reducing the levels of fluid within the body. Also as we exercise our breathing rate increases. In every breath that we exhale there is water vapour. As the intensity of exercise increases so does the rate and depth of breathing resulting in an increased rate of fluid loss from the body via the water vapour on our breath.

How does this specifically affect windsurfers?

Windsurfers are prime candidates for suffering from dehydration. Windsurfing is a vigorous activity, resulting in rapid rates of fluid loss. In addition to this we wear a wetsuit to protect us from variable sea and air temperatures. This wetsuit is a double edged sword for windsurfers! Modern wetsuits are very efficient at insulating the body ensuring that body temperature is maintained, allowing us to continue to windsurf even in cold temperatures. The side effect of this insulation is that the rate of water loss increases as the body temperature increases. One well known racer that I have worked with in the USA needed to drink over 3.5 litres of fluid an hour whilst windsurfing wearing a wetsuit to maintain his hydration status! Even on a cold day a windsurfer will continue to lose water through sweating inside their wetsuit. Unfortunately dehydration is an unseen problem for windsurfers as the obvious signs of water loss such as sweat soaked sports apparel are not apparent as the neoprene absorbs all your sweat!

What effect will it have on your performance?

Dehydration reduces the body’s ability to perform effectively; it reduces our ability to concentrate and makes us more susceptible to fatigue. It could cause our judgement to become impaired resulting in less completed manoeuvres or maybe misjudging a safety situation. If you have ever experienced a mysterious reduction in your ability to gybe towards the end of your sailing session it is likely to be fatigue induced by dehydration rather than you forgetting how to do it!

Dunky - refreshed!!!

An average weight windsurfer (72kgs) would need to lose only 1.44 litres of fluid to experience impaired levels of performance. That is half an hours sailing for the US racer. The same windsurfer would only need to lose 3.6 litres of fluid to experience heat exhaustion. Have a think about how much fluid you normally drink when at the beach. Is it enough?

To put this into perspective the same windsurfer playing in a football match would experience a bodyweight loss of approximately 2.75%. (1.98 litres) If you compare the levels of physical exertion between you playing in a football match and having a good day sailing then I think that you will agree that dehydration is likely to be affecting your levels of performance as a windsurfer.

How do I know how hydrated I am?

The only true way to assess your levels of hydration is to check the colour of your urine using a colour chart.

Ideally your urine should be checked in the morning soon after getting up. If your urine is a darker colour then you should aim to increase your daily intake of isotonic or hypotonic fluids. Fluids that are hypertonic could reduce levels of hydration further. Champagne rather than bitter is the phrase!!

Types of Drink

Isotonic Drinks
	Isotonic drinks are in the same concentration as the bodily fluids. This causes fluids to pass quickly from the intestine into the blood stream providing rapid rehydration. These drinks usually contain carbohydrates for energy and also electrolytes to help replace those lost in sweat. For example SIS PSP22, TORQ Energy. (mixed at 6% solution or below)

Hypotonic Drinks
	Hypotonic drinks have particles that are in a lower concentration that found in the blood stream. This encourages fluids to pass quickly into the blood stream providing rapid rehydration. For example SIS Go electrolyte or very well diluted squash.

Hypertonic Drinks

Hypertonic drinks have particles that are in a greater concentration than found in the blood stream. This means that depending on the concentration of the drink fluids are either slowly absorbed or draw fluids from the blood stream to dilute the concentration of the drink before they are reabsorbed. Hypertonic drinks are generally used to provide energy and as such are not that suitable for use during windsurfing but could be good for replacing energy stores. For example sports drinks mixed above 6% solution.

Make your own sports drinks

Hypotonic drink - for before, during and after exercise

4 fl oz (12 ml) orange squash
1 ¾ pints (1 litre) drinking water
Small pinch of salt

Shake ingredients until well mixed and then chill until needed

Isotonic drink - for before, during and after exercise

2 oz (50 g) granulated sugar or glucose
1¾ pints (1 litre) drinking water
Small pinch or salt

Warm 4 tablespoons of the water and mix it with the salt and glucose or sucrose, add the rest of the water and chill.

Hypertonic drink - for restoring energy after exercise

1 pint (570 ml) unsweetened orange or apple juice
small pinch or salt

Shake ingredients until well mixed and the chill until needed.

Build your own!

An interesting note about tea:


Studies (European Journal of applied physiology 91 (4):493-8,2004) have shown that drinking tea made little difference to levels of hydration but it did significantly improve peoples mood and levels of perceived tiredness – so don’t ditch the post sail cuppa!

What can I do to avoid dehydration?

It is very simple to ensure sound levels of hydration. Each person should be aiming to drink approximately two litres of water each day as part of their daily routine. This will help most people achieve good levels of hydration.


Thirsty work for a world champ		During activity you should aim to replace essential fluids lost during exercise by regularly sipping small amounts of isotonic or hypotonic drink. Care should be taken to ensure that minerals and electrolytes that are lost in sweat are replaced (water alone will not replace these) to keep you going for the duration of your sailing session. The best way to do this is to drink a sports drink that contains a suitable electrolyte mix. The easiest way to buy these is ready mixed but the cheapest is in powdered form – your choice! All drinks consumed should ideally be chilled as this speeds up the rate of absorption.

Calculate your needs:

If you want to work out exactly the amount of water lost during windsurfing sessions the way to do it is:

Weigh yourself in just underwear. Note the weight in kgs. (Weight 1)
Windsurf for an hour. Note the volume of fluids drunk (litres).
Dry yourself and remove clothing except for underwear. Note the weight in kgs. (Weight 2)
((Weight 1 – Weight 2) – fluids drunk)*1.5 = The amount of fluid needing to be drunk per hour of windsurfing.

You need to be weighed without a wetsuit on, as after sailing the neoprene absorbs water and gives a false impression of water loss.

Once you have this information you do not need to repeat this process each time you sail. Approximate based on your ‘usual’ amount of fluid loss. Separate readings for summer and winter sailing would be useful as the higher temperatures of summer will cause a greater fluid loss. Sailors competing should do this process at the end of each day of competition to ensure they are suitably prepared for the next days of competition.

If you wish to discuss any aspects of this article further please email: Tim@f1fitness.co.uk

If you want to buy Nutritional Sports drinks at rock bottom prices check out the Excel document & give Tim a call!

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