The 8 X 8, otherwise known as an 8oz glass of water 8 times a day is a pretty common rule when it comes to hydration. On top of that, you may have even found some formulas that account for age, weight, etc. However, these are meant to be baselines for any given day and don’t really account for extra fluids lost during workouts. Here are some guidelines for how much water to drink when working out.
The following information was gathered during studies through the American Council of Exercise (ACE) and based on guidelines set by ACSM and the United States Track and Field Association (USATF).
Drink 17-20oz Before Working Out
It is recommended that you drink 17-20 oz (500-600 mL) of fluid 2 hours prior to exercise.
To put that into perspective, a typical bottle of water is about 16-17 oz. So a good rule of thumb would be to drink one bottle of water two hours before working out.
Drink 21-30oz While Working Out
For hydration during workouts, it is recommended to drink 7-10 oz (200-300 mL) every 10-20 minutes.
So if we relate that to a 1-hour workout you need about 21-30 oz total. If you can drink a water bottle and a half while working out then you in good shape. This is just a guideline. If you need more, drink more.
Drink 16-24oz For Every Pound Lost
For post-workout hydration, you should intake 16-24 oz of fluid for every pound of body weight lost. Or, 450-675 mL per 0.5 kg lost.
This one requires a little prep work. I recommend this, especially after cardio. Hit the scale prior to your workout and again after. During your post-workout cool-down, drink 1 bottle of water for every pound of body weight lost. You are not burning multiple pounds of fat during your run. It is fluids that need to be replenished.
The More You Know
Well, now you know. The 8 X 8 rule is a solid baseline to live by. Just don’t neglect the additional fluids you lose when you exercise. Those 8 glasses may not be enough to compensate for the sweat equity you are putting into your workouts.
Fitness is a long term journey. Staying hydrated for today’s workout will put you in better position to attack tomorrow’s.