According to Dr. Timothy Noakes author of Waterlogged: The Serious Problem of Overhydration in Endurance Sports, the sport drink industry has managed to create and market a positive image for its products despite being one of the leading contributors to athletes over hydrating. The media as does sponsors of ironman triathlon and marathon, continually give the message to drink before you get thirsty.
When doing exercise in extremely hot environments here are the facts:
The human body can handle transient under-hydration for approximately 4 to 8 hours in duration.
Most individuals involved in intense activities and exercise feel thirsty at about 2% dehydration.
Factoid: To determine your dehydration percentage, weigh yourself naked before and after your workout. A one-pound drop equates to 16 ounces of water loss from sweat
Thirst equates to fluid regulation. To maintain proper hydration levels without over hydrating, do a pre-and post- exercise weigh-ins.
Factoid: Athletes lose more water than sodium, which means under normal conditions, the blood sodium level can actually become more saturated during exercise due to water loss
Exercise induced hyponatremia (low blood sodium) occurs when athletes drink liquids excessively during a prolonged activity. Yet the amount of sodium lost in sweat varies from person to person.
Muscle cramps are more related to fatigue, not sodium deficiency.
Exercise induced muscle cramps occur in muscles that perform excessive repetitive contractions or those prone to cramp due to a mineral imbalance on the inside and outside of the muscle cell.
When cramping, stopping the activity to stretch resolves muscle cramping.
A 2.5 oz. mouthful of pickle juice has been shown to circumvent muscle camps within 90 seconds. Not due to blood sodium levels but rather it is speculated by Dr. Timothy Noakes that the acidity of pickle juice triggers a reflex in the throat that lessens or stops the cramps.
The athlete or exerciser who collapses after activity is more than likely experiencing changes in blood pressure not hydration level, because when exercise stops, the heart stops pumping enough blood to the brain.
The athlete or exerciser, male or female, who feels fluids in the stomach sloshing around, should stop drinking. The body can absorb approximately 600 to 1,000 ml/hour.
Adding carbohydrates, protein and sodium to the water enhances fluid absorption, stamina, and performance levels as well as consuming real foods like pretzels, pickles, chicken broth and a good old fashion ham and cheese with mustard in a wrap.
References:
Nancy Clark, MS, RD, AMERICAN FITNESS MAGAZINE, September/October 2014 issue, Sodium, muscle cramps and sweat losses, page 64 -65.
Dr. Timothy Noakes, Waterlogged: The Serious Problem of Overhydration in Endurance Sports, May 2012, Human Kinetics.