Saturday, January 14, 2012

Dehydration and IMAZ 2011

A few months ago, I wrote up a recap of my IMAZ 2011 marathon, and talked a little about what went wrong.  In short, I stopped taking in fluids during the bike portion, which ended up taking its toll on my during the run.  I came across some info that better explains what happened.

Instead of posting the entire article, I'll just post the pieces that apply to my situation.  You can read the article, in its entirety, by clicking here.

First off, a bit of "duh" information"

"Water is primarily lost from the body via urine, gastrointestinal tract, evaporation from skin, and respiration and is exacerbated by heat, humidity, or fluid restriction during exercise (Barr, 1999)."
I think that part is pretty self explanatory.  In my case, I was peeing, a lot.  It wasn't a hot day, but for some reason, my body was still getting rid of fluids like crazy.  Next point:
"Endurance performance is affected by dehydration as the lower blood volume creates cardiovascular strain, which is exhibited by an increased heart rate and decreased stroke volume (ACSM, 1996). Dehydrated individuals show increased muscle glycogen utilization during prolonged exercise, possibly as a result of higher body temperatures, increased catecholamine levels, or a combination of the two (Barr, 1999; Shirreffs, 2005)."
Just an explanation on how dehydration can affect the endurance athletes performance.  Here's that part that is really important:
"All concluded that dehydration of 2% body mass consistently showed diminished endurance performance in both temperate and hot climates, especially when the duration of exercise was greater than 90 minutes (Barr, 1999; Shirreffs, 2005)."
For me, weighing around 165 lbs on race day, that would mean that once I had lost enough fluids to equal 3.3 lbs, or drop me to a weight of 161.5 lbs, I would start to show a decrease in endurance performance.  Judging by the amount of fluid that I was peeing each time I took a "natural break", I am quite sure that I easily evacuated more than 3.3 lbs, and was nowhere near replacing that amount of fluid.  And that doesn't even take into account the amount of fluid lost from sweating and breathing!  My body was hurting so badly for fluids, and I did the exact opposite of what I should have done.  I should have just kept drinking and stuck to my nutritional plan.  Oh well...that's why I signed up for another Ironman!
Now, I'm not a doctor, and I am not going to, for one minute, pretend that I am all-knowing about dehydration or any other medical problems that can happen during endurance sports.  I just happened to come across a piece of work originally written by K. Doyle, MS, CSCS July 25, 2005.  Again, you can read that paper here.


Thanks for reading!

No comments:

Post a Comment