Hydration is extremely important, you need water for most bodily processes including digestion, absorbing and transporting nutrients, disposing of waste products and keeping your body temperature stable. If you don’t consume enough fluids to replace approximately 2000-30000mL of water lost a day you can become dehydrated. A mere 2% change in body weight caused by dehydration can decrease in your physical and mental performance considerably.

The ACSM guidelines (2007) for hydration and fluid replacement in athletes recommend;

  1. toconsume a nutritionally balanced diet and drink adequate fluids during the 24-hr period before an event, especially during the period that includes the meal prior to exercise, to promote proper hydration before exercise or competition.
  2. that individuals drink about 500 ml (about 17 ounces) of fluid about 2 h before exercise to promote adequate hydration and allow time for excretion of excess ingested water
  3. During exercise, athletes should start drinking early and at regular intervals in an attempt to consume fluids at a rate sufficient to replace all the water lost through sweating (i.e., body weight loss), or consume the maximal amount that can be tolerated. 
  4. It is recommended that ingested fluids be cooler than ambient temperature [between 15 degrees and 22 degrees C (59 degrees and 72 degrees F])]
  5. Addition of proper amounts of carbohydrates and/or electrolytes to a fluid replacement solution is recommended for exercise events of duration greater than 1 h since it does not significantly impair water delivery to the body and may enhance performance


Let’s not forget about the water lost through sweat, athletes can typically lose anywhere between 500 – 2000 ml of sweat per hour. This means about 1-4lbs worth of sweat from your total body weight. Sweat rates can vary tremendously from one individual to the other depending on the activity and the duration. Just remember that hydration zone is losing no more than 2% of your pre-exercise body weight due to fluid loss during exercise (Casa et al., 2000).


For endurance athletes or events in hot weather electrolyte balance is important as a large level of sodium is lost through sweat when exercising. Depending on the individual this could be a large amount of sodium or a little amount of sodium, people tend to refer to this as a “salty sweater”. If you are a salty sweater you would tend to develop a crust of salt on your skin after a workout, or tend to find regular gym clothing starts to get discoloured and turns white. Recommendations suggest The amount of sodium in sweat averages about 500 mg sodium/lb sweat (and ranges from 220 to 1,100 mg) If you lose two pounds of sweat per hour for four hours of intense biking, tennis, football practices, etc., your sodium losses become significant (4,000 mg). You should eat salty foods to replace the losses.


Casa, D. J., Armstrong, L. E., Hillman, S. K., Montain, S. J., Reiff, R. V., Rich, B. S., ... & Stone, J. A. (2000). National Athletic Trainers' Association position statement: fluid replacement for athletes. Journal of athletic training35(2), 212.