Sunday, July 10, 2011

Water Needs in Marathon Running

1. Runners and common population influenced by local babas and messiahs, often consume too much of water, which amounts to six litres and above in 24 hrs. It’s known from ages that, less water intake leads to hypo-hydration (less than default level in the body) and sudden losses lead to dehydration. Athletes and coaches always worried about hydration till we get useful scientific information like this. New studies say that too much could be even worse.

2. Body cannot manage anything in excess even water; more water we push inside, more work for kidneys. Recollect your school lessons; water has to go through circulation and minute tubules of kidney where, many good chemicals are re-absorbed in to circulation such as sugar, vitamins and some trace minerals.

3. Five days before the Boston Marathon, the NEJM (New England Journal of Medicine) published a major article showing that 13 percent of runners in the 2002 Boston Marathon, might have suffered from hyponatremia (low sodium in blood) a dangerous condition caused by drinking too much fluid. The figure was surprising because Boston draws the best, fittest, and most experienced runners in the world. If Boston has a 13-percent rate of hyponatremia, what is it at other marathons?. It is Frightening because four runners, all women, have died of exercise-associated hyponatremia in the last 12 years after participating in marathons.

4. This form of hyponatremia, or low sodium, is caused, when over-hydration takes place during exercise, dilutes the sodium level in the body. This possibly results in the most serious cases: Brain swelling that could lead to seizures (fits) and other life-threatening complications. This makes hyponatremia arguably the most important marathon-related health risk. This is also noticed over a period of time among elderly population who or on supposedly cleansing diet prescribed by local quacks.

5. The history of exercise-associated hyponatremia revolves closely around Tim Noakes, M.D., the noted South African sports-medicine physician. During 1970s, Dr. Noakes was a devoted marathoner who ultimately completed the 54-mile Comrades Marathon seven times. At the time, he wrote three articles encouraging his fellow runners to drink more fluids. But a strange thing happened in the early 1980s. Dr. Noakes started getting calls from athletes and emergency-room doctors faced with a condition never seen before at road races: over-hydration. The runners actually seemed to have consumed too much fluid. In 1985, Dr. Noakes published the similar paper in the field, "Water Intoxication: A Possible Complication During Endurance Exercise." In it he wrote that the condition appears to be caused "by voluntary hyper-hydration.

6. But runners and Ironman triathletes kept developing hyponatremia, Noakes and colleagues continued to publish more papers, and other researchers grew interested in the field. By the mid-1990s, a New Zealand physician named Dale Speedy, M.D., was conducting detailed hyponatremia studies at the Ironman Triathlon in Auckland and found that 18 percent of the Ironman finishers were hyponatremic.

7. By late 2001, Dr. Noakes was invited to write an "Advisory Statement on Fluid Replacement During Marathon Running" for the International Marathon Medical Directors Association. In the paper, he recommended that marathoners drink 400 to 800 milliliters/hour (13.5 to 27 fluid ounces). Dr. Noakes's advice touched off a firestorm, as it was basically 50 percent lower than the widely quoted recommendations of the American College of Sports Medicine, the National Association of Athletic Trainers, and other sports medicine groups, which have generally advised endurance athletes to drink 600 to 1200 ml/hour (20 to 40 ounces).

Problems in Boston

8. Dr. Almond' and his colleagues obtained before-race and after-race body weights and blood sodium levels from 488 Boston finishers, 63 of whom were clinically hyponatremic after the race. The researchers also performed a sophisticated "analysis" to identify what actually caused hyponatremia among the afflicted runners, identifying three primary triggers:

1) Weight gain during the marathon from excessive fluid consumption;

2) A finishing time slower than four hours;

3) Very small or very large body size.

9. Of these, the first was the most important. "The strongest single predictor of hyponatremia was considerable weight gain during the race," the study concluded. Another significant finding: A sports drink doesn't protect you from hyponatremia. "In our subjects, we didn't find that consuming sports drinks was any different than consuming water," Dr. Almond said. "Sports drinks are mostly water themselves, and contain only small amounts of sodium."

10. Gender is not a risk factor for hyponatremia, on the other hand, a lot of women are small and might run over four hours, and those are definite risk factors. At the same time runners should not stop drinking fluids during their marathons, but they should simply aim for a safe middle-ground in their hydration strategies.

Talk About Consumption

11. Hilary Bellamy died from hyponatremia after the 2002 Marine Corps Marathon. According to Dr. Verbalis, hyponatremia was caused by two concurrent events: over drinking; and an "inappropriate hormone response" that limits normal urination. This inappropriate response may be genetic, and can be exacerbated by medications including NSAIDs (pain killers), which many marathoners take to relieve pain and inflammation. But it is also triggered by stress and, especially, nausea--like the nausea marathoners often feel when there's too much fluid sloshing around in their stomach. In the future, the most clued-in experts will no longer tell you to drink XYZ ounces per hour. Instead, they'll say: Drink when you're thirsty; or drink only to the point where you are maintaining your body weight, but not gaining weight.

The Finish Line

1) Don't drink obsessively in the several days before a marathon. Drink when you're thirsty; that will get the job done.

2) Don't take NSAIDs such as aspirin, ibuprofen, or naproxen sodium before, during, or immediately after your race.

3) Weigh yourself before the marathon, and write your weight on the back of your race number. If you need help at the finish line, the marathon medical staff will find this pre-race weight very helpful when they attend to you.

4) During the marathon, drink when you're thirsty, understanding that water, sugars, and electrolytes will help you feel and perform your best. But don't force yourself to drink.

5) Be particularly careful if you expect to run over four hours, and if you have an unusually small or large body size. Drink less if you begin to get a queasy, sloshy feeling in your stomach.

6) Drink sports drinks and also rather than water. But don't expect sports drinks to prevent hyponatremia. They won't.

7) Don't gulp fluids immediately after the marathon. This is a time, according to a 2003 London Marathon report, when the risk of hyponatremia can be quite high, as stomach fluids are absorbed into the bloodstream. Nibble on solid foods and sip a variety of drinks slowly until you feel well recovered.

Happily the word is getting out. After the 2002 hyponatremia deaths at Boston and Marine Corps, the 2003 Boston Marathon had only a six-percent incidence of hyponatremia, and race physicians have told this figure continues to come down. The London Marathon docs say that "after an educational campaign warning runners of the dangers of excessive drinking," there was only one hyponatremia case at the 2004 London Marathon versus 14 the year before.

Prof Dr S Bakhtiar Choudhary

Sports medicine consultant

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