The great risks of hyponatremia were headlined by the New York Times last week (October 20th), in a follow-up to the front page story to the New York Times article April 14, 2005, titled "Study Cautions Runners to Limit Intake of Water."
Hyponatremia is low sodium concentration in the blood (less than 135mmol/L) and the electrolyte imbalance can cause symptoms of nausea, bloating, headaches, disorientation, and rarely - coma or death. Hyponatremia is a serious health condition associated prolonged physical exertion, with some medical conditions, and as a side effect of some medications. As we wrote in a previous article, hyponatremia has been long recognized in athletes, however it has more often been associated with hospitalized patients. With the recent increase of marathons and participants, doctors have been seeing an uptick in the number of cases in athletes. Hyponatremia during prolonged exercise usually occurs when people who are often (but not always) unconditioned, drink too much during prolonged exercise bouts like a marathon or hiking the Grand Canyon. Researchers warn that hyponatremia can be can also be caused by drinking to many electrolyte drinks**.
The following article does not provide diagnosis or advice about this medical condition but looks at the media's presentation of the condition hyponatremia in prolonged exercise. We question the numbers and severe tone of the New York Times articles.
The New York Times' April, 2005 article that an original research article on exercise induced hyponatremia published in the New England Journal of Medicine which that found 13% of participants of a study had hyponatremia. The article indicated that all these marathon runners were in such serious health danger that they could have died from the condition.
This latest New York Times article is now the second to emphasize that vast numbers of runners are drinking too much water. The article quoted the marathon doctor, Dr. Maharam:
"Last year, one percent of the more than 35,000 New York City marathoners developed hyponatremia...and although that is a smaller toll than in other cities' marathons, doctors say every one of those life-threatening medical emergencies could have been avoided."
One percent, 350 marathoners had "life-threatening medical emergencies?" Despite the very real dangers of becoming hyponatremic, the incidence of the condition during marathons is far less than either of the New York Times articles would lead readers to believe. Serious hyponatremia requires hospitalization, so as Acronym Required wrote in our last article, if 13% of all marathon runners were being hospitalized because of hyponatremia, we wouldn't be reading about it in a research report, it would be a major news story after marathons. This has not happened. The news on the health conditions of the runners in the last five New York city marathons was upbeat and cheery, with no mentions of serious helath conditions. If there has been a recent spate of hyponatremic runners it's been a secret well-kept by race organizers, fans, hospitals, and participants.
After the 2004 New York City Marathon, the one that the October 20th in which the NYT article reports that 13% of the runners had this "life-threatening" condition, the same paper -- The New York Times -- previously wrote this in "A Glimpse of Greatness Lifts an Otherwise Dour Day":
"yesterday was unseasonably warm: it was 55 degrees at the start of the race, with a high of 65. Yet the most common injury among the 37,257 marathoners was blisters, race officials said. Although some had heat-related illnesses, there were no reports of runners in serious distress as of 6 p.m."
The New York Times wrote about the 2003 NYC Marathon in "A Great Day for Spectators Isn't So Great for Runners" that:
"Although the unseasonably warm weather may have led to the increase in spectator turnout, several runners complained of cramping and dehydration, and finishing times suffered as a result." But, "[e]arly reports indicated that although the heat caused several runners some distress, no serious injuries were reported....as of 5 p.m., no runners had been reported in critical condition. Event officials said that fewer than 20 runners had been taken to local hospitals."
The New York Times article following the 2002 NYC marathon: "Easy Day For Doctors", quoted the same doctor who is now reporting high incidences of hyponatremia reporting on happy healthy runners: "Maharam...reported that only about 20 of the 31,285 entrants needed more than temporary medical assistance, and by 7:15pm...any runners treated at local hospitals had been discharged..."
In 2001, the New York Times wrote under the headline, "No Major Emergencies", that "[t]he worst medical emergency by late afternoon was of some foreign runners mistaking Vaseline for nutritional goo..." and "by 4:30 p.m. no competitors had been admitted to a hospital."
Finally in 2000, the New York Times noted in an article "A Healthy Performance", that according to Dr. Maharam: "20 out of 29,377 runners had been transported to hospitals...treated for minor injuries and released."
As we previously wrote in April, the numbers of hyponatremia afflicted runners reported by the research report in the New England Journal of Medicine in April and the New York Times coverage of that article seemed at least 10 times greater then the number of people who actually fall sick at races. Similiarly, while this most recent NYT article reports that 10% of the 2004 race runners had hyponatremia, the race report doesn't seem to reflect that rate of illness.
To their credit the New York Times printed a correction about the severity of the condition the next day, October 21. They said:
"A sports article yesterday about the danger of drinking water excessively during marathons misstated the toll of hyponatremia, a resulting condition that developed in about 1 percent of the 35,000 runners in the New York City Marathon last year. Dr. Lewis Maharam, medical director of the race, said that a small percentage of those runners had required hospital visits, and two had required an overnight stay; not all were hospitalized."
However the correction did not change the number of people they reported were afflicted.
The correction still leaves ambiguity about how dangerous hyponatremia is. There was never a correction printed for the first article, which was emphatic about the potential mortality of the disease. Neither of the NYT articles attempt to balance the dire statistics in their story by referring to other articles in their own paper that report on the number of people suffering from the opposite condition: dehydration. Dehydration is also detrimental to health and performance.
Research on the exact physiology of exercise induced hyponatremia is still developing. The risk of these two stories that send terrifying messages about hyponatremia to the public is that if the news article is unbalanced runners may risk not drinking the water they need - especially inexperienced athletes. This is worrisome to physiologists in the field. Reportage about a marathon in D.C. in the fall of 2004 by the Washington Post said this:
"According to Capt. Bruce Adams, the marathon medical director, approximately 45 people [of 17,000 who ran the Marine Corps Marathon] were taken to area hospitals with heat-related illnesses and dehydration, which is about four times as many as last year." (November 1, 2004)
Are people under-drinking now? Or are reports of medically dangerous hydration status simply all over the map? Some doctors vehemently state that dehydration does not occur, others report that many people are suffering from dehydration.
Doctors and researchers understand the basic reasons for hyponatremia, but research continues. One cause is the body's reaction to physiological stress via anti-diuretic hormone (ADH). ADH is released from the pituitary when sodium levels decrease in the body or when blood volume is too low. When runners drink water to the extent that sodium concentrations are significantly reduced, ADH signals the kidneys to reduce output - which is the body's protective response to dehydration. The condition, Syndrome of Inappropriate Anti-Diuretic Hormone (SIADH), is one possible cause of hyponatremia. The most likely cause of SIADH is drinking too much water (the NYT article profiles someone who apparently drank seemingly gallons of water before, during and after the Boston Marathon). However excessive sweating - especially if sodium content is high has also been theorized to be a culprit. Some researcher report that runners can be both dehydrated and hyponatremic, others disagree. Ingestion or overuse of non-steroidal anti-inflamatory drugs (NSAID)(Ibuprofen) has also been associated with hyponatremia.
Appropriate hydration is important to performance. We have a good understanding of the general mechanism, but we don't know why elite athletes don't seem to need to drink as much, while less trained athletes sometimes drink excessively. What is the mechanism of the training effect? Is there research? It's more than an issue of self-restraint as the April NYT article indicated in the quote from one exercise physiologist:
"Elite athletes are not drinking much, and they never have." Dr. Noakes said. The lead female marathon runner in the Athens Olympics, running in 97-degree heat drank just 30 seconds of the entire race."
While the public needs to be aware of the health risks, and certainly running a front page article in the New York Times is a way to garner attention to the issue and potentially reduce liability, hydration is important too. If hyponatremia is simply a more common --but not always dangerous -- physiological effect of endurance exercise and if at levels of 125mmol/L and 135mmol/L people may not have symptoms, this should be presented. Information should not be skewed to scare people from drinking appropriate amounts of water, potentially risking dehydration.
Since there are multiple causes and physiology can vary among individuals, uniform recommendations are difficult to make, as with many health recommendations. Sports medicine doctors warn that athletes should drink no more than eight ounces of water every 20 minutes -- this includes ALL drinks, Gatorade as well as water.
**For example see: (Weschler, L.; "Exercise-Associated Hyponatremia: A Mathematical Review". Sports Medicine, Volume 35, Number 10, 2005, pp. 899-922(24)).
Information and some references can be found at (broken link removed 07/22/12). Note: This site is a commercial site that we are not affiliated with nor endorsing. Their recommendations propose drinking sports drinks. But as the previous citation notes, and race doctors warn: sports drinks provide do not prevent hyponatremia.