Take it With a Grain of Salt: Hyponatremia Risk in Endurance Athletes.

Most of us endurance athletes are health-conscious people.  We sweat every day.  Boatloads of sweat.  We drink tons of water.  We eat our veggies.  All good things right?  Maybe, maybe not.  Sometimes, our health conscious habits get us into trouble and can actually be a detriment to our training.  Especially this obsession we have with hydration.

It’s summer.  Here in the southeast, it is HOT and HUMID AF. You can barely even stand outside in the sun without breaking a sweat, so if you want to beat the heat for your run or ride, you either need to 1) be heading out the door before 6 am or 2) wait until about 8:30pm.  Regardless, though, the temperatures are high and you’re going to be sweating a ton, and likely losing some water weight during your runs that you’ll need to replenish.  Hydration is important, of course, but I would argue that we as an athletic population are way too concerned with water, and not thinking enough about electrolytes – salt in particular.


I have an unfortunate personal experience to share in this regard.  It was early fall of 2014, and I was training a TON.  At least 9 hours per week of running and cycling, PLUS an hour of walking to/from/between classes per day, PLUS lifting three times a week, PLUS weekend hikes…and, being in Virginia in early September, I was sweating a ton.  I was also extremely health-conscious, borderline orthorexic. I never ate processed foods. If I bought anything canned or packaged, I made sure that it was “low sodium”.  I didn’t even own a salt shaker – salt on my food??? No WAY, that will cause high blood pressure!!….right?

That first week of September, I was on my bike pushing hard, and started to feel a little light-headed and nauseous.  My heart started skipping beats, like it was just fluttering around in my chest.  I suddenly couldn’t breathe.  My chest started to hurt. I stopped riding, tried to shake it out, but I couldn’t.  I had to walk the rest of the way home.   I was a little worried – did I just have a heart attack? I’m 25, is that even possible??– but I talked myself down, drank a boatload of water, and resolved to get back out there the next day.

The same thing happened the next day on a run.  On the third day, I took my workouts to the stationary bike on the gym, *just in case*.  By the end of that week, I couldn’t make it past the 40 minute mark in my workouts – my heart would just start jumping into my throat, and my head would start spinning.  I would cool down and leave the gym, but there were days where I couldn’t drive home, I felt so lightheaded.  Eating seemed to help a little, but I’d spend much of the rest of my day in a major fog.

As many of you know, my Master’s degree is in exercise physiology – so as you can imagine, we talk a LOT about the role of the heart in exercise, and about prevention and rehabilitation of  cardiovascular disease.  I’d NEVER thought that I’d be one to have heart problems – hello, I’m an endurance athlete and I eat vegetables and don’t eat salt!! – but I knew from my training that the symptoms of an arrythmia are as follows (ACSM):

-Syncope or Pre-syncope (passing out or feeling like you’re about to)

-Shortness of breath


-Heart palpitations

-Chest pain

UMMM….check check check! These were my symptoms.  I made an appointment with a cardiologist, who did a resting EKG on me that read completely normal, and refused to work me up further because “well you’re an athlete, it’s highly unlikely that you’d have heart problems”.


I wasn’t convinced.  Of COURSE my resting EKG looked fine – I didn’t have these symptoms at rest, after all! So I made an appointment with Student Health, asking for an EKG stress test and bloodwork, which they agreed to. Sure enough….my stress test was positive.  My symptoms came on predictably at the 40 minute mark, and lo and behold, my rhythm was abnormal! Even more telling was the blood work – my sodium levels were abysmally low.  A normal blood sodium level for an adult is 135-145 mEq/L…..mine was 23.  TWENTY THREE. In the words of the physician at student health, “I don’t understand how you’re able to exercise at all!”

I was thankfully not admitted to the hospital, but was given IV sodium at the student health office and some new strict lifestyle instructions.  My orders were:

-No clear liquids.  Only sports drink, no water.

-Sodium tablets daily for 8 weeks

-Salt the $#!* out of my food

-Eat saltier foods

-No exercise until blood levels return to normal.

So. Obviously, I did not die, and I am currently exercising more than 40 mins per day without symptoms. And I do drink straight water on occasion. I’m EXTREMELY lucky that I followed the doctor’s orders and that my arrythmia did not persist – arrythmias and other heart problems are more common in endurance athletes than you’d think.

It just goes to show, though, the important role that sodium plays in our bodies.  I’ll try not to get too science-y on you, but sodium is an ion that plays a HUGE role in the electrical impulses that control our heartbeat! If you don’t have enough of it,  your heart can’t function properly, plain and simple.  “Electrolyte” is kind of a buzzword in endurance sports, but all they are are these ions – charged molecules – that drive the electric impulses controlling heartbeat.  They’re also the driving force behind muscle contractions (they are responsible for the “action potential” that eventually leads to contractile activity).  When you consume plain water, the concentration of these ions in your bloodstream dilutes, which means they are less available for doing the important work of driving your heart and your muscles….and so you end up with muscle cramps (relatively benign), or an arrythmia (potentially fatal).

OVERhydration, then, is a huge problem among health-conscious endurance athletes.  I would argue that this is much more of an issue than DEHYDRATION is, simply because we’ve been so concerned about dehydration that we’ve swung too far in the opposite direction.


Here’s how to combat it: 

Drink to thirst.  The vast majority of literature shows that this is plenty enough.

-If you are doing a long  workout, OR a workout in the heat/humidity, you should not be consuming straight water – you need some electrolytes.  Nuun and Hammer are good options that do not also contain sugar (optimal for workouts under 45minutes).  For workouts longer than 60 minutes, you DO want to replenish carbohydrates – good ol’ gatorade works just fine for this purpose.

-SALT YOUR FOOD.  Do not be shy with the salt shaker!! I think in general, choosing unprocessed, whole foods the vast majority of the time is the way to go, but the salt shaker is absolutely your friend! (unless you do have hypertension, or any other cardiovascular condition, in which case PLEASE consult your physician about your individual sodium needs)

-Be familiar with the signs and symptoms of hyponatremia, which include, nausea, headache, confusion, and fatigue.

The average runner is more susceptible to hyponatremia/overhydration than to dehydration, believe it or not – don’t let it be you!

Happy Running!


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