Hypothermia in Running

Yesterday (Wednesday), I did a talk for the Penticton Tri Club and Running Club.  It was a lot of fun.  I got to talk for 1.5 hours and there were a lot of good questions.  It was a well educated and experienced group so we had some really good discussions.  The focus of the talk was on winter running. 

Before you walk away because you do not think winter running is relevant to you then think again.  We talked a little bit about hypothermia.  Yes, I am back in Canada and yes it is a little colder up here than in Portland, Oregon, but honestly not by much.  Marathons can get cold especially if it is raining outside.  Maybe not in AZ, but in Portland, Victoria, New York and even Chicago or Boston it can get chilly.  And if you ride a bike, things can get a lot colder (even in AZ). 

In the talk, I covered three main topics under the winter theme umbrella.  They were 1) Exercising in the cold and how that affects our bodies, 2) How to gear up for the cold and 3) Winter training (i.e. base or pre-season) recommendations.

One discussion surrounded hypothermia during a rainy marathon.  Apparently a participant had to quit their race early due to hypothermia.  When they measured her temperature it was 32 degree’s.  But, they also found that she had really low blood sugar (hypoglycaemic).  The question was whether the hypoglycaemia caused hypothermia or visa versa.  I honestly said I do not know.

I knew that, yes, low blood sugar could allow the body temperature to drop faster.  I also knew that hypothermia (low body temperature) causes the body to burn more carbohydrates.  But, I do not know for sure which occurred first in this athlete.  A member of the audience pointed out that slowing down also causes thermoregulation problems.  That is true.  It was cold enough outside to cause hypothermia (windy, cool and raining).  Our bodies are very good at producing enough heat during exercise to avoid hypothermia assuming we are dressed appropriately.  However, if we go from running a solid pace, where we are producing adequate heat to keep us warm and give off excess heat to the cold environment, then slowing down, stopping or jogging poses risks.  Running at a slower pace means she was producing less heat and too much heat was being lost to the environment.  Although our bodies can compensate a little in cooler temperatures the situation was beyond the body’s ability to self-regulate.  Thus, she needed more clothes to stay warm which she likely did not have available at that time in the race. 

It is possible this athlete got wet, cold and did not eat enough to maintain her blood sugar thus causing hypothermia.  At the same time, the athlete had either slowed down or was forced to slow down as the race continued, thus, allowing her core temperature to drop further and perhaps quicker.  Or, it could be that the athlete just got tired, slowed down and could not add more clothing.  As they got colder and colder her blood sugar also dropped since more carbohydrates were being burned.  I think you get the idea.  It could be some combination of the above.  Great question and one I do not have a specific answer for.

32 degree’s C seemed really low to me.  Another question was at what temperature is hypothermia dangerous.  I remember reading about different grades of hypothermia but I did not remember the exact body temperatures.  Thanks to the internet, I just found out that hypothermia in medical terms is a core body temperature below 35 degree’s C.  Here is a great description of what happens to us as our body temperature continue to drop:  brrrrrrr….

Goes to show that racing is not always easy (or never easy?).  Proper nutrition, hydration, pacing, clothing and so on can really impact your day.