Written 2002                                                                                                                                                                          

                                                                           Water – Know When To Say When!

By Michael Jacques

 

Water, H2O, the wet stuff... without it life as we know it would cease to exist. For runners it is our very lifeblood. But as Michael Jacques reveals, even with the most essential things we need to know when to when.

 

True Story: Nearing the 35km mark of this year’s Boston Marathon, 28-year-old Cynthia Lucero is starting to struggle. For all but the last 15min she had felt fine. Careful to stay as hydrated as possible she had walked while she drank at every aid station and while others struggled she had taken Boston’s infamous Heartbreak Hill in her stride. But in the time that it took her to run the next 3km Cynthia Lucero’s life unravelled. At the 22mile mark of America’s most famous race she was walking, felt nauseous and told a friend she must be dehydrated. Then in the next breath the friend watched as the walk turned to a wobble and she collapsed. Going into seizure, worried spectators called for an ambulance but by the time she arrived at a hospital Cynthia Lucero was in a coma. Two days later she died !  

 

This shocking account is but one of an increasing trend in endurance sports where participants, especially women, are suffering symptoms ranging from nausea to vomiting, collapse, seizures, hospitalisation… and yes, even dying. But it has nothing to do with dehydration. In fact it is the complete opposite, a case of “over hydration.” And that’s the incredible thing; so dependant are we on fluids for performance, who would ever have imagined that endurance athletes such as we could ever suffer from what is very much a case of getting too much of a good thing.

It’s called  “Hyponatremia,” which according to Auckland doctor Dale Speedy, “Is a loss lowering of sodium concentration in the blood due to water overload.” Speedy is something of a pioneer in research into hyponatremia, one of the first to recognise it as a serious health risk. “What actually happens,” he says, “is water- logging of the cells and brain, which is why people with Hhyponatremia suffer confusion and in severe cases seizures. People can and have died from this!”

Indeed, while there have been no hyponatremic deaths in New Zealand, the American case outlined above is not an isolated incident. In 1993 a 32-year-old women died during California’s Big Sur Marathon and in 1998’s Chicago Marathon a 43-year-old women died, both from complications associated with after finishing the race in a hyponatremic state. Speedy began studying hyponatremia as a result of his involvement as medical director of the Auckland Ironman during the mid-1990s. In It was 1997 he put the entire field through medical screening and found who witnessed the earlier mentioned  “Denis,” and that same year (1997) he that 18% of the finishers finishers were technically hyponatremic. “The majority had no major symptoms, he says, “but 16 people ended up in hospital!”

In the years since, similar figures have been recorded in endurance events all over the world. Athletes are reported to have died in South Africa, and the advent of water as something of a fashion has even seen hyponatremia show it’s ugly face amongst the casual recreation crowd. In 1997, 27 walkers were helicoptered out of the Grand Canyon suffering hyponatremia.

  

 

For the most part, studies indicate water overload asand sodium concentration scenarioas  the principal cause of hyponatremia. The woman who died in the Chicago Marathon is reported to have drank, “gallons and gallons of water daily,” in the two weeks prior to the Windy City race, and in another American marathon a women admitted to hospital with hyponatremia told of drinking 10 litres of fluid the night before. In his Ironman studies Dale Speedy has come across Hyponatremia cases where athletes have drank as much as 23 litres of fluid during the race alone.

However, despite the strong correlations between water overload, Speedy is the first to admit that there is a lot still unknown about what the causes behind it all. Right now, for example, expert opinion is divided as to the relationship between this over hydration and the loss of sodium via sweat. In an address to a sports nutrition conference in February 2001, Dr E. Randy Eichner, M.D., promoted the role of salt loss to sweat as a contributing cause to hyponatremia.

“Studies have shown that athletes can lose two or more grams of salt per litre of sweat,” said Eichner, who is a Professor of Medicine at the University of Oklahoma Health Sciences Centre. “If you consider that athletes may lose up to a litre or more of sweat each hour, you can see that over a long endurance event it is not unimaginable that an athlete could sweat out 30 or 40 grams of salt. Replacing this loss of sodium during an event is critical to performance and safety.”

               The implications of this aren’t lost on Wellington sports dietician Shona Jaray, who says of hyponatremia and salt debate, “It’s one of the great ironies of health and sport. On one side we have this big health push saying we need to reduce salt in our diets. But on the other side we have athletes who lose large amounts of salt due to sweating. Health experts say, ‘ohhh, all that salt can’t be good for your health,’ but the fact is that athletes need more salt than normal people.”

Dale Speedy admits that the logic appeals, but says the scientist in him isn’t sold because, “Studies really don’t support this.” Speedy thinks the real answer lies with finding out why the body cannot absorb or expel this excess fluid during exercise. John Hellemans, a sport medicine physician, coach and world champion triathlete, tends to agree, saying, “It seems to be tied to blood supply to the kidneys being shut down because bloodflow is pulled away to supply the working muscles.”

Both Hellemans and Dale Speedy also wonders if it this absorption problem might have something to do withbelieve that part of the cause behind Hyponatremia may relate to athletes adopting race day hydration regimes that they have not accustomed their body too in training. Speedy’s extreme case of an Ironman athlete suffering hyponatremia after drinking 23 litres on race day is a classic example. With the average finisher clocking around 11hrs 30min, this equates to a massive two litres of fluid per hour! Not only is that too much says Speedy, but “When athletes train usually they usually don’t have the large amounts of fluid available to them like at races. So when they flood the body with fluid on race day perhaps the body can’t cope.”

Experts may be arguing over the exact causes behind hyponatremia, but they have come to conclusions in regard to avoiding it. Science has shown us that at steady aerobic efforts the body loses between 500ml and 1000ml of fluid per hour to sweat. To maintain good health (let alone performance) this obviously needs to be replaced, and if you’re running longer than 90min it needs to be replaced as you go. But this is where over hydration can arise says Speedy because, “ “It’s a wide individual response,”  says Hellemans. “Some people need half a litre and hour, others might need one and half. But anymore than 1200ml per hour is a risk.” Michael – suggest deleting this paragraph – most people who drink even 900ml/h will become hyponatremic and so the figures John is quoting are not appropriate for Ironman although they may be fine for shorter distance events.

Many people have trouble absorbing more than 700ml an hour.” ,” 

The key says Shona Jaray is replacing water lost to sweat at the exact same rate that it is being lost, and then balancing the dilution of the bodiey’s sodium content by replacing it with a drink containing sodium. “The safest way to do this,” adds Jaray, who was one of the first dieticians to promote sodium in sports drinks via her design of the Vitasport product, “is a sweat test.”

               John Hellemans is a strong proponent of the sweat test. “What we do with athletes I coach is weigh them before and after a variety of training sessions. A kilogram lost when exercising relates to about one litre of fluid. So from this we can plot almost exactly how much they need to replace. Then we replace it using a sports drink that contains sodium.”

Hellemans example provides perhaps the best clue to avoiding hyponatremia, because sweat rate not only varies per person but also in relation to variables such as heat, wind, humidity, exercise intensity and the exercise discipline. For example, you will lose far more fluid to sweat during a two-hour run than you will during a two-hour cycle. A hilly run will lose more fluid than a flat run too, because of the increased effort. Likewise, your fluid needs for a marathon in the middle of winter is going to be far less than for a marathon during the middle of summer.

The most important variant when considering sweat rates, however, is the difference between men and women. Both science and history point to female endurance athletes as the group most at risk of Hyponatremia. The scientific explanation is quite simple. “Women sweat less due to their smaller muscle mass and lower metabolism so they don’t lose as much fluid,” says Shona Jaray. And the historical angle talks for itself. In 1997’s Auckland Ironman a massive 45% of the entire women’s field suffered some form of hyponatremia. More recently, studies at the San Diego Marathon revealed female finishers as having the lowest sodium levels. And remember, the only three hyponatremia-related deaths ever recorded in American Marathons have all been women!

Whatever your gender, the problems associated with avoiding hyponatremia is a potentially deadly irony where hyponatremia actually shares many of the same symptoms as dehydration. In this year’s Houston Marathon eight-time marathoner Kathy Schatte was one of four people who suffered hyponatremia. But in Schatte’s case it almost resulted in death after she was presumed dehydrated.

So intent was Kathy Schatte on recording a PB that she had tanked up liberally prior to the race and during the race drunk both Powerade and water at all drink stops. Houston is not known as a hot marathon, so she was taking in far more than her body needed and she finished suffering severe swelling in fingers and hands (basic water intoxication), severe cramps and started vomiting. Presumed dehydrated she was put on an IV, which immediately sent her into seizure and eventually into a coma from which she didn’t wake for two days. When she did wake doctors said they had taken eight litres of fluid out of her and that the fluid had got into her lungs. It was another three days until her Sodium levels were deemed safe for her to be released and three weeks before she could stay awake long enough to go to work.

In his address to the 2001 sports nutrition conference E. Randy Eichner agreed that, “The early warning signs are often subtle and may be similar to dehydration, with nausea, muscle cramps, disorientation, slurred speech, confusion, and inappropriate behaviour.” In an article he wrote for the Sports Medicine Digest following the earlier-mentioned death in April’s Boston Marathon he added that symptoms more specific to hyponatremia were: “bad headache, vomiting, bloating, puffiness from water retention (shoes tight, rings tight, race wristband tight), confusion, and seizure.” But the best advice was his closing comment in the nutrition conference; “If the symptoms are extreme, a medical professional should be seen because at the most extreme an athlete may experience seizures, coma, or death!”

               Despite these warnings a lot of medical professionals see this problem as the domain of extreme people in extreme sports. But John Hellemans isn’t willing to take it so lightly, warning, “As a health risk, overloading is much worse than underloading!” What’s more, in marathon running the latest statistics highlight hyponatremia as afflicting mostly ordinary runners in the middle of the pack. Studies from this year’s San Diego Marathon reveal that no hyponatremia case finished in less than four hours, which happens to be somewhere around the average finishing time for almost every marathon in the world. So don’t let hyponatremia turn you into a statistic – know when to say when.

 

SIDEBAR:

Symptoms of Hyponatremia

Ø       Fatigue, despite adequate fluid intake

Ø       Loss of mental focus

Ø       Nausea

Ø       Confusion

Ø       Vomiting

Ø       Low body temperature

Ø       Weight gain during exercise

Ø       Fitting &/or seizures

Ø       Loss of consciousness

Ø       In extreme cases, coma &/or death!