Importance of Hydration

By Liz

The importance of hydration and the health benefits:    

Are you drinking enough and is it affecting your athletic performance   ?

The health benefits of water        

Water makes up the majority of the body’s weight and supports every aspect of our health, from improving brain function, to protecting muscles and joints, to encouraging dewy and supple skin.

Getting enough fluids keeps your digestive health in balance, too. Water helps absorb some of the nutrients from our food and boosts saliva production to help break down solids.

It’s particularly important if you’re adding more fibre to your diet.

“Water helps to soften fibre allowing it to pass more easily through the digestive system,” said Lauren McGuckin, spokesperson for the Dietitians Association of Australia.

Another core function of water is to keep your body cool, especially as it loses fluids through sweat or illness.


Why is fluid important during exercise?

As water has so many important roles in the body, such as maintaining blood volume and regulating body temperature. During exercise the body cools itself by sweating but this ultimately results in a loss of body fluid which, if not replaced, can lead to dehydration. Sweat production (fluid loss) increases with increasing temperature and humidity, as well as with an increase in exercise intensity. In one hour of exercise the body can lose more than a quarter of its water. Without an adequate supply of water the body will lack energy and muscles may cramp.


Pre-hydration strategy

Before exercise, athletes often fail to hydrate effectively and begin exercise in a hypo-hydrated (dehydrated), state which refers to the state of being in a negative water balance. As little as a 2-3% body mass deficit is enough to adversely affect physical and mental performance during exercise, especially when the exercise is undertaken in hot conditions

When you sweat you lose fluids and key electrolytes, such as sodium, potassium, magnesium, chloride and calcium – crucial to maintaining performance. When playing or training, it is subsequently important to replace both fluids and electrolytes if you want to avoid the effects of dehydration. When dehydrated, your total blood volume decreases, therefore causing a reduction of blood flow to your muscles and skin. Altogether, these responses result in higher body temperatures, reduction of sweat rates, increased muscle glycogen use, increased perception of effort and higher heart rates, all of which contribute to reducing your concentration, skill and physical performance. Given the negative effects of dehydration, it is then crucial that you begin your training session, game or exercise, already in a hydrated state.


Note: As sweat rates vary between individuals, knowing your unique sweat rate and how much fluid you should be drinking is important.


How Much Water Do You Need?

As recommended by the  Nutrient Reference Values for Australia and New Zealand Adult men should drink 2.6 litres of water per day (about 10 cups) and adult women should drink 2.1 litres per day (about eight cups). We much not forget our kids.  Below is a general fluid intake guide for all age groups.

 Recommended daily fluid intake

Approximate adequate daily intakes of fluids (including plain water, milk and other drinks) in litres per day include:

  •  infants 0–6 months – 0.7 l (from breastmilk or formula)
  • infants 7–12 months – 0.9 l (from breastmilk, formula and other foods and drinks)
  • children 1–3 years – 1.0 l (about 4 cups)
  • children 4–8 years – 1.2 l (about 5 cups)
  • girls 9–13 years – 1.4 l (about 5-6 cups)
  • boys 9–13 years – 1.6 l (about 6 cups)
  • girls 14–18 years – 1.6 l (about 6 cups)
  • boys 14–18 years – 1.9 l (about 7-8 cups)
  • women – 2.1 l (about 8 cups)
  • men – 2.6 l (about 10 cups).

Note: These adequate intakes include all fluids, but it is preferable that the majority of intake is from plain water (except for infants where fluid intake is met by breastmilk or infant formula). Sedentary people, people in cold environments, or people who eat a lot of high-water content foods (such as fruits and vegetables) may need less water.

Can you drink too much and what are the risks ?

In cool weather or when the exercise intensity is low, sweat losses may be small. Drinking more fluid than necessary has the potential to interfere with performance (and can be dangerous to health) in several ways. Over-hydration during exercise is called hyponatraemia (dilute levels of sodium in the bloodstream Sodium is needed in muscle contraction and for sending nerve impulses.) Hyponatraemia is rare in the general population. Symptoms include headaches, blurred vision, cramps (and eventually convulsions), and in severe cases, swelling of the brain, coma and possibly death. It is important to note though that this is relatively rare and dehydration is a typically a more common issue for athletes.

For water to reach toxic levels, you would have to consume many litres in a short period of time. Hyponatraemia is most common in people with particular diseases or mental illnesses (for example, in some cases of schizophrenia), endurance athletes and in infants who are fed infant formula that is too diluted.


Recommendations for athletes

Research has suggested that athletes may achieve euhydration prior to exercise by consuming a fluid volume equivalent to 5–10 ml per kilo of body mass in the 2 to 4 hours before exercise (1). It is recommended that an athlete should achieve urine that is pale yellow in colour while allowing for sufficient time for excess fluid to be voided from the body (1,2,4).

Sodium plays a key role in hydration, helping absorb and retain fluid in the body (1,3,5). The concentration of sodium in our bloodstream is normally tightly regulated within a concentration of 135-145 mmol/L. When the blood sodium level drops below the range, this is known as hyponatremia (6). The solute content of sweat is influenced by a number of factors, including the sweating rate and acclimatization status of the individual (6). Some athletes are ‘salty’ sweaters, which is highly individual. For these athletes especially, increasing sodium levels in the diet (particularly pre-exercise) is important to maintain performance in the heat and/or for prolonged periods of time.

Follow this example plan for a 70kg athlete preparing for a competition:

  1. Wake up – 250-500 ml fruit juice/water with breakfast
  2. 3-4 hours prior – 500-750 ml with electrolyte.
  3. 30-60 minutes prior– 250 ml electrolyte (at this stage your urine output should have reduced and any urine passed should be pale yellow)
  4. During your workout or physical exercise, drink another 250 ml every 15 minutes.

As always, you should practice your pre-hydration in training before trying in competition.


One more things… Checking the colour of your urine.

For more information:


  1. Thomas, D. T., Erdman, K. A., & Burke, L. M. (2016). American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance. Medicine and Science in Sports and Exercise, 48(3), 543.
  2. Shirreffs, S. M., & Sawka, M. N. (2011). Fluid and electrolyte needs for training, competition, and recovery. Journal of sports sciences, 29(1), 39-46.
  3. Casa, D. J., DeMartini, J. K., Bergeron, M. F., Csillan, D., Eichner, E. R., Lopez, R. M., & Yeargin, S. W. (2015). National Athletic Trainers' Association position statement: exertional heat illnesses. Journal of Athletic Training, 50(9), 986-1000.
  4. Armstrong, L. E., Herrera Soto, J. A., Hacker Jr, F. T., Casa, D. J., Kavouras, S. A., & Maresh, C. M. (1998). Urinary indices during dehydration, exercise, and rehydration. International Journal of Sport Nutrition, 8(4), 345-355.
  5. Stachenfeld, N. S. (2014). Sodium Ingestion, Thirst and Drinking During Endurance Exercise. Sports Science Exchange, 27(122), 1-5.
  6. Lara, B., Gallo-Salazar, C., Puente, C., Areces, F., Salinero, J. J., & Del Coso, J. (2016). Interindividual variability in sweat electrolyte concentration in marathoners. Journal of the International Society of Sports Nutrition, 13(1), 31.


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