Did I Get Hyponatremia at the World's Toughest Half Triathlon?

Two days after completing the "World's Toughest Half" the headache I developed on the run finally started to subside. My quads still ache when I stand up, but I can deal with that kind of pain.

Hard to see, but my fingers were terribly swollen

Tuesday morning, as I was getting ready for work, HS noted that the bloating in my belly was going down. I could tell the difference too and thought "What did I do to myself?" I told him I thought I looked bloated in some of my race photos and he agreed. The definition was gone in my arms and my belly looked a little distended. I actually believe I managed to gain weight during the race!

My bloating was bad enough that during the run, my fingers became so swollen that they hurt to bend. They looked like fat little sausages sticking out of my hands. Now, swollen fingers are not something new for me, but it usually happens on a long run in 90+ degree heat.

The last few days at work have been torture. I have been tired, sore, and my head throbbed. It was all I could do at lunch to Google my symptoms. One thing that kept showing up in my various searches...hyponatremia.  Could I have been over-hydrated and/or had too low of sodium levels?

The Basis of My Diagnosis 

According to the Korey Stringer Institute at the University of Connecticut, several factors increase an athlete's risk of hyponatremia including:

• Exercise lasting more than four hours or a slow pace (Yes on both) 
• Being female (Check)
• Excessive fluid intake during the event (Water, Gatorade and/or Coke at every stop)
• Pre-exercise over-hydration ( (I drink a LOT of water everyday, HS says too much)

Guilty!

The Ultra Marathon Cycling Association describes bloating hyponatremia as having a distinct set of symptoms beyond just low sodium. These include visible puffiness around sock lines, waistbands, wrists and hands, a forehead headache that worsens on bumpy roads, weight gain during the event, nausea, and in serious cases altered mental status — which they note represents a medical emergency requiring immediate attention.

I won't claim to look like the Michelin Man, but I do know that HS and James were laughing at the size of my arms in a picture of me on the bike. I don't think it was muscle so much as bloating.

The same source explains that it's possible to take in fluids faster than the kidneys can process them, leading to bloating. More confusingly, some athletes experience a complete urination shutdown even when mildly overhydrated — the opposite of what you'd expect. The danger is that a non-urinating athlete is usually assumed to be dehydrated, when in fact they may be dangerously over-hydrated.

Without going into too much detail, let me just say that after I warmed up my wetsuit in Folsom Lake, I didn't go to the bathroom again until I was back home in Stockton...over 9 hours later! And that was after drinking  3-1/2 bottles of sports drink on the bike, fluids at every aid station on the run, and a large ice filled diet coke when we stopped to gas up the truck.

One More Thing

Hyponatremia isn't just an athlete's problem. According to the American Academy of Family Physicians, a significant percentage of elderly people in long-term care facilities show signs of the condition. Women entering menopause are also at elevated risk due to hormonal changes that affect the body's ability to regulate sodium levels.

Great! Just freakin' great!!!!

Plan Going Forward 

I'm not sure if this was my problem or not, but I'm going to take a little precautionary measures to see if I notice a difference in how I feel...especially now that the weather is heating up and my race season has officially started. Here are some of the things I am going to try:

• Weigh myself before and after long training sessions
• Start taking electrolyte tablets during hot and/or long training sessions
• Reduce the amount of water I drink during the day
• Salt my food a little bit more

2026 Update

The World's Toughest Half no longer exists — the race was discontinued. If you want the full story of the race that caused all of this, read the World's Toughest Half 2016 race report.