Nutritionists say we need to drink at least 64 ounces of water every day, but you need to drink more if you’re exercising, particularly in the summer heat. Des Moines-based physical therapist Dave Freeseman says you should drink water or sports drinks in the two hours before you work out. During your workout, drink eight-ounces of water for every 10 minutes you exercise. He says people usually find better results when they stay hydrated.Outdoor activity in the heat can be just as heart stopping as winter-time activities like scooping the driveway. Freeseman says people with heart problems need to take extra precautions, like frequently checking their heart rate by taking their pulse.Doctors say the heart has to work harder when the body loses fluids, so it’s very important to keep hydrated. Water is the liquid that’s most quickly absorbed by the body; sports drinks and juices are absorbed more slowly because of their sugar levels.