Did you know? Exercise associated low sodium can have serious consequences

What is exercise associated hyponatremia?

Exercise associated hyponatremia (low sodium) can be caused by a loss of sodium (like sweating), an excess of total body water (drinking isotonic water), or a combination of both. Hyponatremia is serious issue and can lead to delirium, seizures, or even death.


What are the symptoms of low sodium?

If you are engaged in strenuous exercise, be on the look out for these signs and symptoms of hyponatremia:

- Lightheadedness

- Dizziness

- Nausea

- Puffiness

- Vomiting

- Headaches

- Frothy saliva

- Altered mental status, confusion, agitation, disorientation


What causes hyponatremia?

Examine your exercise routine to see if you have any of these risk factors that could potentially cause hyponatremia:

- Overdrinking water and other hypotonic beverages

- Weight gain during exercise

- Exercise duration greater than 4 hours

- Slow running or performance pace

- High or low body mass index


The prototypical patient that experiences exercise associated hyponatremia is a smaller individual who trains at a slower pace and drinks more water than they sweat out.


What should I do if I have signs and symptoms?

Alot of the cases are seen at an event like a Triathlon or a marathon.  The medical tent staff will assess you if it is suspected and manage accordingly.  If you are having symptoms after exercising on your own, then the first thing you should do is seek a medical professional. If your vital signs are stable with mild symptoms, then expect your doctor to put you on fluid restriction and observation until urination. For fluid replacement, at an event we will add 3 small salt packets to Gatorade if oral intake is tolerated. If symptoms are severe, it is recommended to get 3% oral saline solution if tolerated and taken to a medical facility for further evaluation. 


How do I prevent exercise associated hyponatremia?

Prevention of exercise associated hyponatremia is achieved by proper fluid consumption. You do not want to drink excess fluids and it is recommended to use your thirst as your guide. Practice your hydration on your training runs, bike etc, especially the long distance when you'll be assimilating race distances.  Drinking only when thirsty should limit excessive drinking and therefore prevent developing hyponatremia.  Dr Carfagno is the medical director for Ironman AZ and the Rock and Roll Marathons.  He can help guide you on hydration and nutrition strategies for you.  He also has an top-notch referral source of coaches he works with that can help train you. 


Dr. David Carfagno is a Board Certified Internist and Sports Physician, who trained at the Cleveland Clinic Foundation


Sharwood K, Collins M, Goedecke J, et al. Weight changes, sodium levels, and performance in the South African Ironman triathlon. Clin J sport Med 2002

Spasovski G, Vanholder R, Allolio B, et al. Clinical practice guideline on diagnosis and treatment of hyponatremia. Eur J Endocrinol 2014