Dec
Hyponatremia
Good, but it Needs A Little Salt
“Low salt”… “Salt free”… “Low sodium”… these products are all over the shelves of your Whole Foods and HEB. Is this what we should eat?
What is Hyponatremia? (hi-PO-na-tree-mee-uh)
Table salt, sodium chloride, is lost in sweat and urine and replaced by food. The sodium part (of sodium chloride) is vitally necessary for such body functions as muscle contraction and transmission of signals along nerves. The average American diet has more than enough sodium to keep these functions going… for most people.
The body has excellent adaptation mechanisms in the kidney, sweat glands, and blood vessels that maintain blood sodium levels in a very tight range of about 135-145 meq/L. Going much outside this range means trouble. So the maintaince system is very efficient. Ultra endurance events challenge this efficient survival mechanism.
Imagine your body is a glass of salt water. Poor out (sweat) some of this water. Replace it with tap water. This glass (your body) is now low in sodium compared to the original glass. This low blood sodium or hyponatremia can be tolerated for a brief period of time. But do this for 4-12 hours or more, and potentially dangerous symptoms result. In fact 30% of Hawaii IM finishers are hyponatremic.
Sweat contains 2-3.5 grams of sodium per liter. (The more trained you are, the more dilute your sweat, the better your body can conserve salt.) Triathletes can easily sweat more than 1 liter per hour during training. In a 12-hour race, that could mean 24-42 grams of salt lost. Replacing with only water causes hyponatremia.
Aspirin, ibuprofen, and other anti-inflammatory that tri racers frequently pop, interfere with kidney function and contribute to the development of hyponatremia. Under tough conditions you need your kidneys need to function at 100%.
Symptoms of Hyponatremia
Blood sodium levels below 125 produce symptoms. You’re probably familiar with the symptoms of hyponatremia: nausea, muscle cramps, and irritability. At this point many athletes think they’re dehydrated and drink more water, making the problem worse. In the past, the medical tent at races would treat these symptoms with intravenous fluids. The American College of Sports Medicine now calls such practice the “dehydration myth.” These early symptoms should be treated with salty foods and some sports drink.
More severe symptoms include seizure and coma. Of course if your training buddy has these symptoms, get him to medical attention immediately. The medical team will likely go with intravenous HYPERnatremic (high salt) solutions to rapidly elevate serum sodium level to a “safe” level of 120-130 in a few hours, followed by a gradual increase to normal over the next few days. Entirely too many athletes have died of hyponatremia.
Prevention of Hyponatremia
No clear-cut recommendations work for all. So I stress that you know your sodium needs prior to race day. Practice your hydration, eating and salt strategy during training. In general, events more than 3 hours require sodium from sports drinks. When going more than 5 hours (ultras, IMs) salty foods are necessary. Most authorities and I recommend against salt tablets (unless your very experienced with them) which may give you too much salt.
Get used to reading FDA labels. Remember training removes 2-3.5 grams of sodium per hour. Do not try to replace all of this during your workout. Rather increase sodium intake for several days prior to a long event. Then shoot to get about 1 gram of sodium an hour during training. This will keep you out of trouble. The ideal training food has both sodium and carbs. Here are a few favorites:
Serving Sodium (mg) Fat (gm) Carbs (gm)
Gatorade 8 oz 110 0 14
Exceed 8 oz 50 0 17
Salted pretzel 10 reg size 300-500 0-1 19-22
Fat free saltine 5 crackers 130 0 11
Other great choices are chicken noodle soup (a must at IM), pickles, and tomato juice. The exact amount of sodium varies among brands.
Recommendations
1. Increase sodium intake by 10-20 grams per day for a few days before the event.
2. Use a sodium containing sports drink when going for a long time.
3. Shoot to get one gram of sodium per hour during the event.
4. Weigh yourself before and after training. Drink enough sports drink to keep the numbers the same.
5. Avoid aspirin, ibuprofen, and other anti-inflammatories.
6. Discourage the practice of “drinking the maximal amount of water that can be tolerated.”
Don’t get rid of your saltshaker, know your needs, eat well, drink the right fluids, and go like hell.
Have you tried a new hydration tool called ‘AquaJoe’. It allows for much easier hydration.
December 24th, 2007 at 10:05 amNo, I haven’t tried that one, but a quick look at their website leads me to believe that it may be a welcomed addition to one’s hydration belt. One of the more basic keys to hydration is drinking something that you will enjoy, otherwise you wont hydrate like you are supposed to. This may help those trying to avoid water and hyponatremia associated with lack of electrolyte replacement and over indulgence at the water stations.
December 28th, 2007 at 7:54 pmAre you familiar with the drug Florinef used to control vasovagal syncope? As an endurance athlete, how should I manage my fluid and electrolyte intake to compensate for the potential magnesium/potassium depletion associated with this drug?
April 23rd, 2008 at 7:09 amGreat question Greg. For those of you not familiar with this type of diagnosis Vasovagal Syncope (Neurocardiogenic Syncope) is a neural mediated disorder characterized by basically ‘passing out’. There can be multiple reasons for this condition, each with their own remedy. Florinef is one medication that is often used to decrease/resolve the problem. A common side effect of this medication is electrolyte imbalances caused by fluid shifts into your blood vessels. Fluid shifting into your blood vessels helps maintain your blood pressure but at a cost….low potassium(hypokalemia) and sometimes magnesium (hypomagnesemia) and elevated sodium (hypernatremia). There are regimens to correct these electrolytes. Those regimens vary depending on your dose of Florinef, diet, reason for the disorder, your other medical problems and medications. In a very basic sense, loss of potassium and magnesium from your system will cause generalized fatigue and more importantly can be dangerous for your heart. Many of those on Florinef require frequent evaluations of those electrolyte levels. Interestingly, potassium absorption will not happen if your magnesium level is not adequate. That being said, there are a few other vitamins that are important to maintain as well. As an endurance athlete you are wise to raise this concern as Florinef use now requires a delicate balancing of all the above. mentioned factors with your workouts, hydration status and symptoms, and the cooperation of more than one specialist. Magnesium and Potassium supplements should never be take outside the guidance of your doctor. Greg, Ill email you personally with more info.
April 23rd, 2008 at 8:36 pmI have found that either salty pretzels or even pedialyte works. You can even make homemade pedialyte. The plain generic kind is really cheap, has no sugar and comes in small bottles you can keep in the car, too. I cannot ingest much sugar, so this is a great alternative for me. But you do just have to figure out what works for you.
August 29th, 2008 at 8:33 pm