Answer for When are electrolyte/sports drinks necessary?
It seems to me that you're basically asking 2 questions:
- Under what circumstances do most people need to drink sports drinks to recharge their electrolytes?
- When drinking large amount of water (it sounds like you drink up to 3 gallons per day), does a person need to make a special effort to replenish electrolytes?
I'll do my best to address both these questions based on the research I've done.
First of all, it's important to understand what "electrolytes" are. Essentially, an electrolyte is a charged mineral or salt. Electrolytes used by the human body include sodium, potassium, chloride, calcium, magnesium, and some others. Sodium and potassium are the electrolytes of which we generally lose the most when exercising (largely through our sweat).
Your body requires a certain amount of these substances to function. However most people consume more than enough of these electrolytes every day. Sodium in particular is something that most Americans get in much larger quantities than their bodies need. Although you lose sodium, potassium, and other electrolytes, sports drinks contain more than just electrolytes. They also contain sugar, and of course water. The general advice I've read is that if you're doing exercise for less than 1 hour, you probably don't need to worry about replenishing your electrolytes. You'll still have plenty left. If you're exercising to lose weight, drinking a sports drink after your work out may hinder your progress. You need to consume less calories than you burn, and the extra calories from the sugar in the sports drink may negate the extra calories you burned during your workout, resulting in little net benefit from your exercise.
On the other hand, if you're going to be running a long-distance race, or doing some other lengthy endurance exercise, you should be concerned about replenishing your electrolytes and rehydrating properly. You'll also need carbohydrates to keep you fueled. In this case, sports drinks may indeed be helpful.
For those running a marathon or long distance race, Livestrong makes the following recommendation:
When running a marathon, you must create an electrolyte replacement strategy. A variety of electrolyte replacement options is available. Examples include sports drinks, which contain both electrolytes and water to prevent dehydration. Gels also are available in small pouches and contain a concentrated amount of electrolytes. Jelly beans known as sports beans also can be used for electrolyte replacement. You can eat nutrition bars and sodium-containing foods such as pretzels, bananas and animal crackers. When choosing the best electrolyte replacement for you, consider portability and what will be easiest for you to carry with you on race day.
Marathon runners and training coaches Gary and Ellen Bloome recommend drinking one cup of an electrolyte-containing drink every 30 minutes during competition. Train with your electrolyte replacement drink of choice in order to ensure it will be sufficient to replace your losses. If you utilize electrolyte or carbohydrate-containing gel packs, the Bloomes suggest consuming one every four to six miles. If you utilize food or bars to replace electrolytes, break these into small pieces and consume some every 20 to 30 minutes.
Furthermore, the Wilderness Medical Society says this about endurance exercises:
The American College of Sports Medicine in its position statement, currently recommends a fluid intake during exercise of 600-1200 mls/hr. The fluid intake of most of the reported cases of exercise associated hyponatremia has been at the middle or upper end of this range challenging this as an appropriate fluid intake. A more realistic intake is likely to be 500-750mls/hr. Whether this fluid should contain salt as well remains unproven. Intuitively, it seems prudent to use a proprietary sports drink containing 20-30mmol/l of sodium if this is available, rather than just water.
As regards the water drinking question. About.com has this to say about water intoxication and electrolytes:
The kidneys of a healthy adult can process fifteen liters of water a day! You are unlikely to suffer from water intoxication, even if you drink a lot of water, as long as you drink over time as opposed to intaking an enormous volume at one time. As a general guideline, most adults need about three quarts of fluid each day. Much of that water comes from food, so 8-12 eight ounce glasses a day is a common recommended intake. You may need more water if the weather is very warm or very dry, if you are exercising, or if you are taking certain medications. The bottom line is this: it's possible to drink too much water, but unless you are running a marathon or an infant, water intoxication is a very uncommon condition.
However, the Encyclopedia of Nursing & Allied Health says:
Overhydration is an excess of body water that results when water intake exceeds output. Drinking large amounts of water does not typically lead to overhydration if the kidneys, heart, and pituitary gland are functioning properly. An adult would have to drink more than 2 US gallons per day (7.6 L per day) to exceed the body's ability to excrete water.
It sounds like you're drinking up to 12 liters, which is more than what the encyclopedia above seems to consider safe. So you might want to cut back. Also, it seems that drinking more than 1.5 liters in a short time (less than an hour) may also be dangerous, and you should be more conservative if you're on a low-sodium diet.
If you are drinking too much water, and your electrolyte balance is poor, some early symptoms may include nausea and vomiting, headache, fatigue, muscle cramps, spasms, and bloating. If you start to experience these things, stop exercising or doing things that would make you sweat, and try to improve your electrolyte balance. Eating a banana might be good, if you want to avoid taking in more liquid. Please note that the symptoms of dehydration are similar, however. Also cramps experienced during exercise are not necessarily caused by hydration or electrolyte problems.
Please note that I am not a doctor, dietician, or scientist. The above should not be taken as medical advice. If you're feeling like you might have an electrolyte imbalance, do not ignore your symptoms because of anything you read here. If you have further questions or concerns talking to your doctor and/or doing further research would be prudent.