Drinking too much or being dehydrated can decrease your workout productivity. To determine if you are well hydrated, take a look at your urine volume and color. If your urine is light yellow in color and you are going on a regular basis (every 3 to 4 hours), you are well hydrated. If your urine is dark, you are dehydrated.
It is important to make sure you are well hydrated before working out. It is recommended to drink between 8 to 16 ounces of water 15 minutes before your workout. During your workout, it is recommended to drink 4 to 8 ounces every 15-20 minutes. If you are working out vigorously for over 90 minutes, it is recommended you drink 8 to 10 ounces of a sports drink every 15 to 30 minutes.