Does it matter?
Yes, and in this blog entry I’ll begin to explain why…
Most of us can probably remember being taught in Biology class that “the make-up of the human body is roughly 70% water”. In real terms lean muscle tissue contains 75% water, blood contains 83% water, body fat contains 25% water and even bone contains 22% water.
We’ve all probably also been told that in a dire situation the human body can survive for weeks without food - but without water survival times are dramatically reduced – dehydration can kill in a matter of hours in the most extreme of environments. This is no coincidence, we need water to function.
For the vast majority of the population in the developed world, dehydration isn’t a life and death issue, we take access to drinking water for granted. However, dehydration can lead to health issues and is an important consideration in sports performance.
So… How much water should I be drinking?
The average sedentary person in a temperate climate should be fine drinking 8-12 glasses of water per day, many people however don’t manage that (especially when it is pointed out that coffee, cola and similar drinks containing caffeine DO NOT COUNT), thus leading to a perpetually dehydrated state affecting mental alertness and impaired performance (both general and sporting).
… and if I’m training or playing sport?
Dehydration in an athlete has dramatic negative ramifications for levels of speed, strength, stamina, alertness and co-ordination. As little as a 2% decrease in body weight through dehydration can have a significant negative effect on performance levels.
For an athlete at any level, water intake required to remain hydrated significantly increases from that required by a sedentary person. With exercise the body looses water in many ways, particularly through respiration and sweating. When we sweat not only do we lose water, we also lose electrolytes (mineral salts the body needs to carry out chemical reactions) these too need to be replaced.
Post exercise, re-hydration is one of the keys to optimal recovery. A body with the correct balance of fluids is in the best state to repair and recover from the exertions of exercise. Replacement of the electrolytes lost through sweating is also essential so as to maintain the mineral and chemical balance of the body.
How do I know if I’m hydrated or dehydrated?
When monitoring hydration it is possible to get as scientific as you can imagine using labs and expensive pieces of equipment. However, in practice there are some simple markers to use to monitor your hydration levels.
- Urine Colour – This is easy, when pass water, observe the colour of your urine. The darkness of the colour indicates the concentration of the fluid, and therefore the water content. Ideally a light straw colour should be observed indicating sufficient hydration, any darker colour indicates dehydration – the darker the more severe.
- Body Weight – Most useful when trying to calculate how much water is needed to replace fluids lost through exercise. Weigh yourself pre-exercise in a hydrated state, and then again post-exercise. The difference between the two weights indicates the weight lost through dehydration… and therefore the amount of fluid needed to re-hydrate. For every 1kg lost aim to consume 1.5 litres of fluid in the following 2 hours. (Example: if a rugby player weighs 94kg before the warm-up and 91kg after the game, he has lost 3kg and needs to replace 4.5 litres of fluid to rehydrate).
What’s best to drink? There are so many options!
There are many different branded sports drinks on the shelves claiming different things on the label, it can become very confusing.
They are all branded as sports drinks, but they differ greatly in terms of what they do. There are some common terms used which are worth understanding to make an informed choice. The terms refer to the concentration of the sugars and electrolytes in the drinks compared to that of your body fluids. Here’s a brief explanation:
“Hypotonic”
Hypotonic drinks are less concentrated than your body fluids, meaning that the drink is absorbed into your system very quickly as it contains little in the way of electrolytes or sugars.
“Isotonic”
The name Isotonic indicates that the drink has the same or similar concentration of sugars and electrolytes to your body fluids, meaning it is not only absorbed quickly but also allows for effective refuelling, an ideal combination during sports activity.Isotonic drinks should ideally contain 6g of carbohydrate per 100ml for optimal absorption.
“Hypertonic”
Hypertonic drinks are much greater in concentration of sugars and electrolytes than the bodily fluids. Therefore they absorb much more slowly and are less effective at re-hydrating the body. However, as refuelling drinks they are effective post sport.
… and when?
This is a common question. The normal assumption is that “if I’m thirsty – it’s time to get a drink”.
This is not the case.
In truth, we get thirsty as the body’s response to there being an undesirable increase in the concentration of salts in the body fluids (due to a decrease in water). If concentration has reached that point, you’re already significantly dehydrated and you’re already fighting a losing battle.
As an athlete, if you start exercising in a dehydrated state you are only going to make the situation worse. Therefore, it is essential to begin exercise fully hydrated.
When we exercise we lose water all the time, so to combat the negative performance related effects of dehydration it makes sense to include some sort of re-hydration strategy to your sport – the longer your event in duration, the more important this becomes. Consuming little and often is a good rule of thumb.
Are there other factors to consider?
Environmental factors are the most important to keep in mind. Obviously when it is hot we will sweat more, losing more water and electrolytes. Humid conditions will also increase the rate of dehydration as the body sweats more but as the sweat doesn’t evaporate there is no cooling effect. So the body sweats some more, this can lead to dehydration very quickly.
And what’s so bad about Alcohol, Coffee and Cola?
From a physiological point of view, alcohol and sports don’t mix well, but that’s a topic I’ll leave for another blog entry!
In terms of the relationship between alcohol and dehydration, there is a strong link. Alcohol is a strong diuretic, increasing urination to a level more than is necessary for the body – leading to dehydration. The morning after “a couple of drinks” you will most likely be significantly dehydrated and not in an ideal state to begin exercise, as you will become more dehydrated.
Often people finish their exercise and proceed to consume alcohol. Although they are replacing volumes of fluid, the alcohol in the fluid acts as a diuretic and they end up making themselves more dehydrated and thus significantly impairing recovery.A good compromise is to ensure that the body is completely rehydrated and refuelled for 2 hours before you allow yourself an alcoholic drink.
Coffee, Cola and certain energy drinks all contain high levels of caffeine – another strong diuretic, they therefore have a similar effect.
Too much of a good thing?
It is important to be aware that you can over do it in terms of hydration. A state known as hyponatremia occurs when too much water has been absorbed into the body. This leads to “water intoxication”. So much water has entered the blood stream that it dilutes the mineral and chemical balance of the blood interfering with the brain, heart and muscle function. This can be serious in extreme cases.
In Conclusion
It is fair to say that although hydration can have such an impact on our sporting performance and general health, it is one of the easiest factors to keep control of. It takes a little fore-planning but can make the difference you’ve been missing out on.