Along with monitoring heart rate the ACUMEN EON 202 watch provides an indication of the level of dehydration. The purpose of the dehydration reading is to remind an individual to drink fluids. It takes the human body 12 to 24 hours to replace fluids from heat and exercise. To prevent the harmful effect of excessive dehydration it is necessary to drink before you becoming thirsty. The thirst mechanism is not precise in humans. An individual can lose fluids equaling up to 3% of their body weight before the thirst mechanism tells the person they need fluids. Strength and endurance are reduced by 10 to 15% after a 2% loss of body weight, through dehydration. Most people need more than eight - eight-ounce glasses of water per day. The water intake each day needs to be ????? ounce per pound of body weight. Do not drink over 32 ounces at any one time. Do not consume more than four - eight ounce glasses of water in any one-hour. Divide the water intake over the entire day. If the exercise period is under 60 to 90 minutes water is always appropriate. If the exercise period is more than 60 to 90 minutes a sports drink offers an energy advantage during exercise that can enhance stamina and endurance. Cardiac drift occurs because dehydration causes a drop in blood volume with less blood being pumped with each heartbeat. The Heart rate increases 7 beats per minute for each 1 percent loss in body weight due to dehydration.