With the warmer weather starting to appear more regularly, and summer officially here in Australia, I thought it was time to write about hydration. While drinking water seems simple enough, many people just don’t drink enough to stay properly hydrated.
WATER IN THE BODY
Water is one of the key substances required by the body to function. It is used in metabolic reactions; it helps to transport blood and nutrients around the body; it assists in the elimination of toxins; and it is a component of the body’s cells. Water is also vital in helping to regulate body temperature. Water is contained in the body’s tissues, as well as in the fluids circulating around the body.
Typically, a healthy male will have about 50 to 65% of their weight as water; while females will have between 45 to 60%. However, the different types of tissues within the body have varying amounts of water within them. For example, body fat usually contains around 10% water, while muscle tissue is made up of about 75% water.
WHAT HAPPENS WHEN WE SWEAT
When we exercise, our metabolism increases to create energy, which we burn. One of the results of this is an increase in body temperature. As our bodies begin to heat up, more blood is circulated to the extremities (arms, legs, hands and feet) and to the skin, in order to allow the body to cool down. If we get hot enough, we begin to sweat.
Sweating is where the body allows fluids to pass through to the surface of the skin, where it can evaporate. This creates a cooling effect for the skin, which, in turn, can cool the blood which is circulating beneath the skin surface, cooling the body down.
On a day to day basis, the loss of water through sweat is comparatively small…..only about 400ml per day. But when we exercise, the amount of water lost as a result of sweating increases dramatically. In extreme circumstances, the body can lose 2 to 4 litres of water every hour as a result of sweating.
But our sweat doesn’t just contain water. Other substances such as sodium, magnesium, potassium and calcium (in addition to many other trace elements) are secreted in small amounts when we sweat. As a result, salt can often be found on the skin or clothing once the water has evaporated!
HOW ELSE DO OUR BODIES LOSE WATER?
Water is lost from the body in a few other ways. In addition to sweating, water is lost in small amounts through our breathing, and also through our faeces.
But one of the bigger ways we lose water is through our urine. Water is required to assist in the clearance of toxins from our bodies when we go to the toilet. On average, we typically lose around 1.5 litres of fluid every day as a result of urinating…..of course, this figure varies depending on a large number of factors!
DEHYDRATION
Dehydration occurs when the body loses water which is not being adequately replaced. When we are exercising, the more dehydrated we become, the more impact it has on our performance.
A loss in body weight of around 2% as a result of dehydration can impair performance to a degree; while a 5% loss in body weight will seriously impair performance. A body weight reduction of 6-10% can stop exercise performance altogether; as well as causing serious problems such as heat exhaustion and heat stroke.
Heat exhaustion and heat stroke are where the body has lost its ability to remain cool, and the body temperature begins to rise to dangerous levels. This can quickly damage the body’s vital organs…especially the brain, heart, kidneys and muscles. If not treated quickly, it may also lead to death! Heat exhaustion should be taken seriously and treated as soon as possible; while heat stroke should be considered as a medical emergency. Below is a list of the signs and symptoms of heat exhaustion and heat stroke….if you are beginning to experience any of these, stop exercising and seek treatment as soon as possible!
Heat exhaustion Heat stroke
- Excessive thirst • High body temperature
- Heavy sweating • Lack of sweating
- Fatigue • Rapid breathing and heart rate
- Headache • Rapid heart rate
- Dizziness • Confusion • Nausea and vomiting
HOW TO RE-HYDRATE AND STAY HYDRATED
The best thing to do to avoid dehydration is to drink fluids regularly and stay properly hydrated. But how much should you be drinking? Ultimately, this figure varies depending on the amount of fluid you are losing. The old rule of 8 glasses of water a day is always a good start. But if you are doing a lot of exercise, or it is a bit hotter than normal and you are sweating, you will probably need to drink more.
When we are exercising, small, regular amounts of fluid are the best. Drinking 150-250ml of water every 15 to 20 minutes is adequate for most types of exercise; but this of course can vary depending on the type of exercise you are doing, as well as how hot it is. Remember, it is possible to lose up to 4 litres of water through sweat in extreme conditions!
Don’t start to think about rehydrating when you begin to feel thirsty…..at this point, you are probably already a little bit dehydrated. You should start your fluid intake before you even begin to exercise, continuing to drink both during and after finishing your activities.
As we can lose extra minerals in our sweat, it is sometimes a good idea to drink something other than just water. For shorter types of activities, lasting less than an hour, water is usually good enough, as everything else is replaced through a healthy, balanced diet. But with longer types of endurance exercise, where we can sweat for hours on end, products like Hydralyte and Gastrolyte can help to replace things like sodium, potassium and magnesium, which are lost through sweating.
OVER HYDRATION
While staying hydrated is vitally important, too much fluid intake can also cause some issues. If your body takes on too much water, it can dilute the fluids flowing around your system…..this can effectively reduce the concentrations of vital elements and minerals in your body, which can cause problems such as agitation, nausea, muscle cramps and lethargy.
However, this is usually not a big problem. In healthy individuals, the body can normally deal with excess fluid intake quite effectively…….you will just find yourself going to the toilet on a very regular basis!
WATCH YOUR WEIGHT AND LOOK AT YOUR URINE
For athletes, two of the best ways to monitor your fluid levels are to keep and eye on your weight; and look at the colour of your urine.
Closely watching your weight will give you a bit of an idea of how much fluid you may have lost as a result of your exercise. Many athletes weigh themselves both before and after exercising, with a drop of weight used as an indicator as to how much fluid has been lost; and hence how much needs to be replaced.
The colour of your urine is also a good indicator as to how well hydrated you are. Typically, a well hydrated person will pass pale, straw coloured urine. A darker colour can indicate dehydration; while clearer urine can indicate that somebody is drinking just a little bit too much. But of course, things like vitamin B supplements can change the colour of urine to a bright yellow; and diuretics such as alcohol and caffeine can cause clear urine to be passed, even in somebody who is a little bit dehydrated!
While keeping an eye on your fluid intake is important all year round, with summer finally here it is more important than ever……always remember to take adequate fluids with you when you are exercising, and keep on top of your hydration!
The Sports Pharmacist 