Greg Eskedjian, MSc. CSCS


More than half of our bodies are made up of water, which is stored in our cells, muscles, blood and organs. We also have lots of water stored outside of our cells (extracellular fluid), which is the fluid we lose when we sweat. This fluid is not just water; it is salt water, with about 9 grams of sodium (salt) per Liter of fluid.


  • Water serves a number of different roles in the body, including:
  • Maintain blood volume
  • Remove wastes & toxins
  • Regulate body temperature (sweating)
  • Nerve function
  • Shock absorption & lubrication


Severe Dehydration

When we lose a certain amount of internal water, or do not drink enough, we can become dehydrated. When we become severely dehydrated (large amounts of fluid loss), we can be at risk of serious health problems, such as heat exhaustion or stoke.

Mild Dehydration

Mild dehydration, which is not a health risk, can affect performance in athletes. *2% body mass loss during exercise can result in decrease in both physical and mental performance.

EXAMPLE: If you weigh 1551bs (70kg), 1.4 L is 2% of your body mass.

During intense competition lasting an hour or more, it is not uncommon for athletes to lose much more than 2% of their body mass, with research showing sweat losses of as high as 5% in an hour of competition.

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