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Wednesday, October 5, 2011

Sweat & Salty

Swollen
I frequently obsess about the edema my body experience(s/d) in all my ITI races. I've had it in severe form and mild. While the 2008 race was the most severe, (injuries + 17 lbs of edema), the most severe form of straight-up edema (without injury) was coming into Rohn (2010) about 200 miles into the race. That was bad.
Edema in Ruby, 2008 ITI
I have asked other racers if they experience swelling. Most admit to a much milder version at one time and others, I get a shrug of the shoulders as it's par for the course. I now pay particular attention to the way people look at the end of the race in McGrath. Swelling is easily explained right? Punishing our bodies to extreme limits, days at a time on lack of sleep can certainly account for a build-up of toxins and cause some localized swelling- especially if there is an overuse injury.  But edema is the buildup of fluid in the body not localized except by gravity (my face was puffy when lying flat and my legs swollen when upright).


Before the Susitna race this year I asked a friend of mine, who is a sports medicine doc and knows my history, to consider me a patient . He mulled it over and finally said "it's got to be hypoanatremia, there's no other explanation". Hypoanatremia is a situation where there is too little sodium in your body fluids. It is a well known condition in any endurance race and can be dangerous. You may start retaining fluid (though there are other serious conditions that cause edema in ultra's) and many ultra running races have weigh in stations to check weight for this condition.  


Sodium
Nutrition is easy to blame in endurance races. Hitting the wall, bonking, dying like a pig whatever the term it's all related to reaching a point of depletion, nutritional or training related. I've spent a lot of time thinking about replenishing calories during a race and less on "electrolytes". Lately I've been more focused on electrolytes. Electrolytes are generally sodium, chloride and potassium lost by sweating. Sodium replenishment is easily overlooked, after all, every trail food on the planet has salt (sodium chloride) in peanuts, jerky, pretzels, Cheetos, potato chips, etc and every checkpoint we gorge on some super high calorie yummy sodium filled delights.  If anything I assumed I was low on potassium and that was the major reason for adding electrolyte tablets.


Occasionally, I follow some of the ultra running races and read race reports with interest in their nutrition description. I noticed that many of the top racers are "eating" not only gu packetsss an hour but also adding an S cap each hour. It seemed standard practice and I began to pay more attention to sodium. Sodium and potassium loss is entirely dependant on how much we sweat and other complicated individual physiological factors, but most directly related to sweat. According to this article in sports medicine the recommendation for endurance racing (longer than 4 hours) is to replenish 300 - 1000 ml of water an hour and about .5 up to 1 gram of sodium (~2.5 grams of salt) per hour! First of all that's quite a range and shows how varying conditions (temperature, humidity) can be in a race. Second of all that seems like a lot per hour for a lower intensity 350 or 1000 mile (cold temp) snow bike race. 


Then I read this article on horse racing and electrolyte replenishment, made me glad I wasn't a horse. A horse can sweat 10 liters / hour when racing in some cases. That's 50 grams of sodium, 83 chloride and 52 grams potassium. 50 grams of sodium would be 10 cans of spam an hour! Ouch, can you imagine carrying hydration and calories for a race with that amount to consume? Thorough bred horse racing is intriguing because there is a ton of money on a good horse.  It pays to know these things and the owner/rider is going to push that horse to its' limits.  Me, on the other hand, I ain't no thorough bred but I do put myself on the edge physically at times.  It's nice to know electrolyte replacement is not unique to human athletes. 


Na+ Calculations
In the 2008 ITI by day 10 I had been doing consecutive 18 hr days of bike pushing. When asked about my nutrition I would say “yes, I felt like I was completely replenishing my electrolytes…” Hmmm, 18 hrs a day of exhausting bike pushing through deep snow—according to the article above I should be taking in 9-18 grams of sodium/ day!!!... that’s something like 18 cans of beef broth or 18 bags mountain house meals or 30 (2 oz) bags of Cheetos or 4 complete bags of pretzel rods or 54 gu packets a DAY just to get my sodium. Not quite a horse's intake but um no, I wasn't even close not even half.


In the 2010 ITI I came into Rohn unrecognizable with swelling. It was (hot) close to 40 degrees and I had been pushing for over 24 hrs straight. It took me 16 hours to recover and keep going. And I did keep going all the way to Nome and didn't swell again after that. Why? Don't really know. The temp dropped -20 to -50 the rest of the race, maybe I didn't sweat as much?


2011 Tri's:
Lake Stevens Triathlon (Temp 60-70)    Timberman Tri (Temp 80-90)
Time:                         5 hrs 00 mi                                   5 hrs 01 min
Hydration:      2 liters with 2 nuun tabs          3 liters with 2 nuun tabs
Caloric intake:       1,000 (5 gu packets)                   1,000 (5 gu packets)
Sodium intake:          1.6 grams                                         1.6 grams
Possible Na+ Used  5 grams                                           5+ grams 
Na+ depletion:       3.4 grams                                        3.4+ grams 


It's science but not really rocket science, it's more of a "duh" moment than an "aha" one.  But we'll see if improvement is on the way. I rec'd my S Caps in the mail, now I just have to get out for a long ride....and I have another dr. f who may be willing to complete basic blood panels to check my personal electrolyte levels throughout.... so...to be continued..






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