Why HydrateTo perform at the peak of your athletic ability, proper hydration is of the utmost importance. During exercise, your heart increases the blood flow to the muscles (in use) and the skin (to cool your body down). Through perspiration, your body loses about 1-litre (32 oz) of water per hour based on moderate activity. If you don’t replace the water you lose, your body starts to become dehydrated. At a higher heart rate and core temperature, your body can’t produce more energy, leaving you weakened and much more vulnerable to heat illness (symptoms such as headaches, nausea and muscle fatigue)
The best defense against dehydration is a good offense – drink often – at least 1 litre (32 oz) per hour for moderate activity in moderate conditions. It’s also better to drink continuously – 6 to 8 oz every 15 to 20 minutes is recommended by the American College of Sports Medicine. Remember that thirst is a delayed response, and by the time you’re thirsty, your body is already dehydrated. Always carry some sort of bottled drinking water.
For endurance athletes, the USA track and field advisory also suggests adding 700mg of sodium per litre (32 oz) of water. This, or the occasional salty or powerbar-type snack, will help prevent the onset of hyponatremia, a rare condition that occurs when the level of sodium in your blood gets dangerously low. This condition is rare but can occur after a full day of strenuous activity.
The USATF also suggests using hydration systems to help keep fluids cooler, making it easier for your body to absorb.
Dehydration can set in sooner than you think. You can easily lose 2 litres (64oz) / hour on a hard ride or a run on a hot day, but even recreation outdoors enthusiasts can lose up to 1 to 1.5 litres per hour. In a recent position statement of the National Athletic Trainers Association, as little as a 1 to 2 percent lose of fluids could negatively affect function and performance. A 1 to 2 percent loss of fluids can occur after a little more than one hour of moderate activity in cool weather without water. At 3 percent, the risk of potential heart illness increases exponentially.
2% of body weight lost
3 lbs of fluid lost (1.5 litres)
Happens in about 1 hour
Decreased athletic performance, decreased muscular endurance
4-6% of body weight lost
6-9 pounds of fluid lost
Happens in about 2 to 3 hours
Muscle cramps, loss of strength, fatigue
6 to 8% of body weight lost
9 to 12 pounds of fluid lost
Happens in about 3 to 4 hours
Dizziness, serious fatigue, nausea, high temperature
7 to 8 % of body weight lost
11 – 12 pounds plus fluid lost
Happens in 4+ hours
Confusion, loss of consciousness
Rob's note: This article came to be because of a percieved need to make new participants of Warrior Camp aware of the need to be hydrated before attending camp.
Hyponatremia related articles:
Emergency Medicine: Hyponatremia
Labels: peak potentials