Did you know:

losing just 2% of your body weight from dehydration can decrease your performance up to 10%?

Dehydration also impairs a persons ability to dissipate heat (sweat), causing increased risk of heat related illnesses. Hydration is important for general health as well as exercise performance. Many people have asked me how many ounces of water to drink each day. I used to tell them 91 oz or the standard 8 glasses of 8 oz of water a day. While popular myths still conclude that there is some magic number of ounces of water to drink for hydration, modern science would say that they are missing the mark. Hydration is much more than just water and more complex than just monitoring your thirst. It may seem like a simple topic but hydration scientists research many topics including optimal hydration, staying hydrated, dehydration, mineral and electrolyte loss, body fluid management and sweat rates to name a few. These topics and their results can be the difference between a good work out and an injury. Keep reading to find out more about how hydration is affecting your body and your work out.

Hydration Stages- How it works

During hydration, the body:

  1. Receives fluid through intake (drinking and eating)

  2. Absorbs it through the gastrointestinal tract

  3. Disperses it to various places where it may be needed

  4. Uses it to flush out toxins and keep the body temperature stable through secretion

We are using the word fluid while we talk about hydration because using the term water is not entirely accurate. Hydrating fluid usually has some amount electrolytes including sodium, potassium, magnesium and also a small amount of carbohydrates (sugar). This electrolyte “solution” as it is called, can help retain fluid in blood and expands plasma volume for cardiovascular function and is more effective in hydrating the body than just water alone.

The fluid in our bodies does a number of amazing things like:

  • regulate temperature

  • regulate blood pressure

  • transport nutrients

Definitions to know: 

Extracellular Hydration- The fluid in the body outside of cells, in the tissue and around the organs

Plasma– the fluid in the blood stream around the cells, comprising the largest fluid balance in the body

Plasma Volume– The total volume of blood in the body

Extracellular hydration is very importance to performance because it directly effects plasma volume. Fluid balance is maintained by Antidiuretic Hormone (ADH), a hormone that directs the flow of fluid in or out of the blood stream. It controls plasma volume and osmolarity (thickness). Thickening (or increased osmolarity) happens with dehydration and is responsible for the majority of the symptoms you feel during dehydration.  You can see that if plasma osmolarity is high due to dehydration, blood can become thicker and harder for the heart to pump. Thicker blood causes delays in delivering fresh oxygen and energy to the muscle cells. Low plasma volume and high osmolarity also create high blood pressure and decreased brain function due to slower delivery of oxygen and energy to the brain. To correct this, increased osmolarity in the blood volume will stimulate the release of ADH. This will result in increased fluid re-absorption into the blood to thin it out, more concentrated urine due to less output, and less concentrated plasma volume. Conversely, osmolarity decreases with over-hydration as well and stimulates the dispersion of fluid out of the plasma as needed.


Check out this table for signs and symptoms of dehydration

to make sure you are doing your part to stay hydrated