Water loss can affect your body in many adverse ways. It takes only 1 to 2% water loss to negatively affect your aerobic endurance. Unfortunately, your thirst mechanism is not triggered until this amount of water loss has already occurred. 3% water loss may reduce your anaerobic endurance. Your muscle strength will be reduced at 4% water loss. 5% water loss will result in heat exhaustion, muscle cramps, fatigue, decreased blood pressure, and increased heart rate. Heat stroke and possible coma may result when 6% water loss occurs. 10 to 20% water loss will cause death.
You should drink liquid (preferably water) almost every hour throughout the day because a sufficiently hydrated body is a happy body. Plus, and this is very important, staying hydrated allows you to have more energy due to the increased circulation of nutrients (e.g., glucose, amino acids, fatty acids) within your blood stream. Waiting to drink water by the time you get to the gym is too late. You need to drink water regularly at least four to six hours prior to your workout to feel energized and ready to take on those weights. In the event you did not hydrate in advance before your workout, simply drink ice water instead. The cold water allows for quicker emptying from your stomach and thus increases rehydration rate--ideal before, during or immediately after training.
The dangers of dehydration are very real, especially as we get older. This is because the older we get, the less efficient our body's thermoregulatory mechanism becomes. Translation: we don't readily recognize the feelings of thirst as we age and losing more than 10% of body weight in fluid can be fatal. Dehydration can cause a whole host of problems including the following:
- Decreased temperature regulation which may cause overheating
- Increased muscle fatigue
- Decreased strength
- Decreased food metabolism
- Decreased athletic performance
- Decreased energy level
- Possible heart malfunction
- BMR (Basal Metabolic Rate)--Drink 80 to 100 ml per every 100 calories of your metabolic rate (i.e., if your BMR is 2000 calories, then you should drink 1.6 to 2.2 L daily).
- Bodyweight--Drink 30 to 40 ml per kg bodyweight (i.e., if you weigh 100kg, then you should drink 3 to 4 L daily). Another recommendation is to drink half of your body weight in fluid ounces daily (i.e., if you weigh 200 lbs, then you should drink 100 ounces daily).
Before your workout, you should drink about 500 ml of water. During your workout, you should drink about 250 ml of water per every 15 minutes. Ideally, you should drink 16 ounces (2 cups) of water for each pound of bodyweight lost during exercise. Remember that exercising in a hot, humid environment means more sweating which means a faster rate of dehydration (i.e., it may only take 30 minutes before dehydration has occurred). Dehydration can readily occur in cold weather conditions as well because of water lost from breathing, sweating and increased urine production. Cold temperatures may decrease the thirst mechanism so you're likely to drink less. When drinking water to replenish lost amounts, you should aim to drink only 16 ounces in 15-minute intervals in order to allow the body time to absorb the fluid. By the way, the Center for Science in the Public Interest (CSPI) has found that nearly half of bottled waters comes from municipal sources and not from mountain streams as advertised on the labels. This means that tap water has as good a quality as most bottled waters for drinking.
Brian Danley, CFT
"Motivation is what gets you started. Habit is what keeps you going."