Hydration in sport by Harry Ogata

It is a subject that is quite neglected in Badminton clubs and in general, but is quite important - especially to some of us who train hard and play hard. I hope that whatever you do in regards to hydrating yourself during sports this may make you feel comfortable in your regime or give you more understanding in what you can improve on.

Before I go into HYDRATION we should understand a little about what DEHYDRATION is.

Dehydration

Sweating is the clever way in which the body maintains its core temperature at 37 degrees Celsius. This results in the loss of body fluid and electrolytes (minerals such as chloride, calcium, magnesium, sodium and potassium) and, if unchecked, will lead to dehydration and, eventually, circulatory collapse and heat stroke. The effect of fluid loss on the body is as follows:

% body weight lost as sweatPhysiological Effect
2%Impaired performance
4%Capacity for muscular work declines
5%Heat exhaustion
7%Hallucinations
10%Circulatory collapse and heat stroke

So as you can see, as you reach 2% loss of your own bodyweight in sweat your performance starts to deteriorate. You can easily work out how many in litres this is for you. We hope you never reach 10%.

You start to dehydrate if your body is unable or is not given the opportunity to absorb water at the same or faster rate as it is losing it.

How do you know you are dehydrated?
1) If you are feeling thirsty (and we don't mean the need to have a pint) then you are already well into the realms of being dehydrated.

2) If your urine is a dark colour and you are not going as often then, again, you're dehydrated.

3) On the court, this could include a higher heart rate, slower reaction time, decreased coordination, impaired concentration, and a greater perceived sense of the difficulty of the task you are doing.

4) For those of us who digress to the pub too often for too long then a 'hangover' is a sure sign of dehydration due to alcohol being a diuretic.

Be aware that you don't have to be doing physical exertions/exercise/pubbing to become dehydrated. Just not drinking enough of the right fluids can lead to dehydration.

So what has this go to do with Badminton, all the extra training you are doing on the side and the way we feel sometimes after a little exertion? You're drinking enough surely and you feel alive and well.

Well, going back to what was said at the beginning, you sweat during exercise and this leads to water loss and crucially loss of important electrolytes. You also lose fluids through breathing and there has been plenty of heavy breathing on court. This in turn could lead to poor performance - simple!

So why is Hydration important?
Well water is the lubrication of life. Water and its constituents are what make life tick. But it's not just a case of "filling yourself with fluids and you're good to go", especially if they are the wrong type of fluids e.g. alcohol.

So what are the internal and external influences that can affect what you drink and how much?

Consider the different range of drinks in order of importance in rehydration: Water, Sports Drinks, Juice, Carbonated Soft Drinks, Coffee & Tea, Alcohol. These will influence the internal absorption of fluids and electrolytes.

Water - is considered the best for rehydration BUT has some physiological constraints. It is absorbed in the gut very quickly, but lacks the electrolytes. So is good for rehydration for normal low day activity, getting up in the morning etc. When it comes to exercise the rapid absorption into the blood stream dilutes sodium concentration and a feedback mechanism in the brain halts the feeling of thirst. Therefore athletes are likely to take less fluid. Also it can be quite bland especially in large quantities.

Sports drinks - are considered more efficient at getting fluids in and at the right quantities with the benefit of carbohydrates and electrolytes but can be counter effective to the very reasons some people exercise i.e. to lose weight. So for example, high carbohydrate drinks can counter affect a weight loss regime exercise or damage teeth due the high concentration of sugars. Flavouring is known to induce a higher intake by athletes.

Juice - provides more of the necessary carbohydrates for more endurance athletes.

The others - rehydrate in declining efficiency due to their chemical makeup, but it's suffice to say these would not be suitable for an athlete who trains for more than an hour at medium to high intensity.

Consider the different aspects of training and environment.

Intensity and humidity are the external influences that determine what, how much you should drink.

Day to day non-sporting activity or exercising for less than an hour per day in comfortable conditions requires just plain water.

Exercising for an hour or more or whenever conditions are hot or humid low-carbohydrate electrolyte drink is a better hydration option than plain water. A sports drink is the very best method for both rehydrating and refuelling when conditions demand it. A low-carbohydrate electrolyte drink is appropriate if the intensity and duration of the exercise don't demand refuelling and if sweat losses are not at their highest. Otherwise a high-carbohydrate drink should be considered.

Isotonic/Hypotonic/Hypertonic - are all sports drinks the same?
Confusingly, no!

Hypotonic drinks contains a less concentrated carbohydrate solution (1-3%) - promotes good fluid absorption.

Hypertonic drinks contain a carbohydrate concentration greater than 10% - these will have a slow gastric emptying rate, thus decreasing fluid absorption.

Isotonic drinks contain a carbohydrate (glucose) concentration of 6% to 8% - quickly replaces fluids lost by sweating and supplies a boost of carbohydrate. This drink is the choice for most athletes.

There are now fluid replacements that concentrate purely on electrolyte balance.

A few notes on electrolytes:
Electrolytes provide the electrical charge that keeps the heart, muscles, and nervous system working properly. Diet, climate, stress, exercise, illness and medications all impact electrolyte levels.

Common signs of electrolyte imbalances are low or high blood pressure, fatigue, circulation problems, illness and disease.

Electrolyte replacement fluids claim to do so without upsetting the body's mineral balance or adding carbohydrate calories. This is an interesting area and I have come across a few athletes who incorporate this method in their rehydration regime.

So know you should have the gist of the types of drinks you can and cannot have and which environment and types of exercise you can take them.

Having explored the influences placed on our bodies that determine our fluid regime we can now explore the variety of drinks on the market and how we should or should not take them.

It's important to point out that re-hydration is IMPORTANT but this is not me marketing a range of energy drinks for you to try or depend on. Knowing your own body, exercise regime and taking appropriate action is the key to improving your performance.

There is a plethora of re-hydration marketing guidelines by drinks companies sponsored scientists. This is a massive area of business in the UK. I will have to let you draw your own conclusions to these creative marketing. But do check out their contents and chose those appropriate to your own needs.

For now we'll keep it simple by understanding the basics of hydration and following general and sensible measures to make your own informed choice of drinks.

General Guidelines for Fluid Needs during Exercise
While specific fluid recommendations aren't possible due to individual variability, most us can use the following guidelines as a starting point, and modify the fluid needs accordingly.

Hydration before Exercise
• Drink about 400 - 600 ml, 2-3 hours before exercise
• Drink 200 - 300 ml, 10-15 min before exercise

Hydration during Exercise
• Drink 200 - 300 ml, every 10-15 min during exercise
• If exercising longer than 90 minutes, drink 200 - 300 ml of a sports drink (with no more than 8 percent carbohydrate) every 15 - 30 minutes.

Hydration after Exercise
• Weigh yourself before and after exercise and replace fluid losses.
• Drink 600-700 ml water for every 500g lost.
• Consume a 4:1 ratio of carbohydrate to protein within the 2 hours after exercise to replenish glycogen stores.


Want to make you own sports drink?

Isotonic
200ml of orange squash (concentrated orange), 1 litre of water and a pinch of salt (1g). Mix all the ingredients together and keep chilled.

Hypotonic
100ml of orange squash (concentrated orange), 1 litre of water and a pinch of salt (1g). Mix all the ingredients together and keep chilled.

Hypertonic
400ml of orange squash (concentrated orange), 1 litre of water and a pinch of salt (1g). Mix all the ingredients together and keep chilled.

Small note on salt:
Sodium is readily available in the form of salt. When we sweat and exercise sodium is the element lost most (in relation to the other elements). As the other elements loss are small there is no need to replenish them immediately as a good varied diet will replenish these in good time.

Marketed Sports/Energy drinks
There is a ship load of Sports drinks on the market all purporting to boost hydration and performance. There doesn't seem to be any science to prove one way or the other any of them are better or worse than each other. Like I said, follow simple guidelines to the concentration of carbohydrate to match your level of exercise intensity. Harry Ogata plays for Hale Badminton club, Harrow

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