To keep your body full of energy and performing at its best,
good hydration is essentialWe all need around two litres
of fluid a day to keep our bodies properly hydrated. Water
is the medium in which most of body processes take place,
and makes up about two thirds of body weight. Right now
50% of the population is poorly hydrated. We lose water
via breathing, sweat and urine.
The functions of Water
- Regulates Body Temperature
- Lubricates joints
- Assists digestion & carries nutrients throughout the body
- Diffusion of gases insuring a moist environment (breathing)
- Waste products leave the body through water
- Gives each cell in the body proper form
The recommended daily two litres of fluid should come from
water, plain or flavoured. We also get approximately half
a litre from food eaten each day, about a quarter of daily
needs, mostly from fruit and vegetables. Of course, alternatives
to water do tend to have more calories, so it makes sense
to get at least some of our daily fluid needs from water.
Also, some studies have indicated that drinking plenty of
water is beneficial to the immune system; good for the skin;
alleviates constipation and can reduce the risk of kidney
Dehydration can make you feel tired and lethargic, and
will decrease your capacity for exercise. Extra fluid is
needed in hot weather and when you exercise. For each hour
of exercise you should drink an extra litre of fluid. If
you have an illness that is causing sickness, diarrhoea
or sweating, you will need to up your fluid intake to make
up for the extra loss.
Hyponatremia, also called water intoxication, is generally
the result of drinking excessive amounts of plain water
which causes a low concentration of sodium in the blood.
Once a rare occurrence at sporting events, it is becoming
more prevalent as participation increases and more novice
exercisers are entering endurance events.
Hydration and Exercise
Proper hydration is helpful for achieving the best performance
in elite athletes. Adequate fluid intake is also helpful
for recreational exercisers to exercise at their best. There
have been recommendations about how much water or sports
drinks are needed and over the years athletes were advised
to drink much more water than we now know is necessary.
New Guidelines on nutrient recommendations were published
by the Institute
of Medicine of the National Academies (external link).
They state that the vast majority of healthy people adequately
meet their daily hydration needs by letting thirst be their
guide. They don't provide specifics, such as the number
of glasses of water per day, because fluid needs can be
met through a variety of sources besides drinking water
The group makes special
recommendations for athletes (external link) in the
area of water, sodium and potassium.
The International Marathon Medical Director's Association
also revised guidelines regarding hydration for athletes
in May 2006. They recommend drinking a sports drink when
exercising thirty minutes or more. They also state that
during a marathon, it's best if runners listen to their
body and drink when they feel they need to.
For many exercisers water intoxication is a very real and
very serious complication from drinking too much water.
The numbers of triathlon and marathon participants, who
develop symptoms of water intoxication, continue to grow
as more and more novice exercisers have entered these events.
So what is the right amount of fluid to drink? Well, that
all depends, and in fact, it may not be that important to
try to figure it out.
The longer and more intensely you exercise, the more important
it is to replace lost fluids. And for an elite athlete,
a loss of two percent of body weight in fluid has been linked
to a drop in blood volume. This makes the heart work harder
in order to move blood through the bloodstream. For elite
athletes this decrease can result in a slight decrease in
performance. Dehydration in athletes may also lead to fatigue,
poor performance, decreased coordination and muscle cramping.
The American College Of Sports Medicine provides guidelines
for athletes regarding proper hydration and fluid replacement.
If you feel that you need some sort of guideline to determine
how much you should be drinking, use the following as a
Drink no more than 1 glass of water every twenty minutes.
You can also weigh yourself before and after you exercise
to get a sense of how much fluid you typically lose. One
kilo is equivalent to approximately 750ml of fluid.
Sports drinks can be helpful to athletes who are exercising
at a high intensity for 60-90 minutes or more. It's necessary
to replace losses of sodium, potassium and other electrolytes
during exercise. Keep in mind that under normal situations
most exercisers are unlikely to deplete these minerals during
regular training. If, however, you find yourself exercising
in extreme conditions or for long times (an Ironman or ultra-marathon)
consider adding a sports drink with electrolytes.
Hyponatremia may occur during longer events when athletes
drink excessive amounts of plain water.
The Pee Test
Thirst is not a good indicator of dehydration. Use the
pee test to assess how hydrated you are.
When you are well hydrated, your pee should be the colour
of pale straw.
This relates to colours I or 2 on the chart.