Tuesday, 28 August 2012

Sleep deprivation and running performance

You know what seems to be the cool thing to do these days?  Running events that are way too long (for me).

I remember when I was in elementary school, the 800m was the longest race ever.  4 loops of the 200m track? Impossible.

Then, in grade 8, the 1500m came along; the ultimate test of endurance (or so I thought).

But boy things have changed.  Athletes are now competing in 100-mile trail races, 8 day stage races (like the ENDURrun) among other similar yet equally punishing events.  When did the marathon all of a sudden become a speed-oriented event?

Needless to say, with the popularity of these ultra events rising, the competition is starting to become much more fierce.  As a result, athletes are looking for new ways to tackle the entire host of new challenges that this type of racing introduces.

Nothing like a 24 hour marathon in Namibia!

Among the most significant of these new challenges: sleep deprivation.

The solution to sleep deprivation is an easy one (sleep more).  But just how much does sleep deprivation impact an athlete over a 24-hour period?  That's what I wanted to start looking at with this blog.


2009 study looked at this issue in an interesting way as they took into account both the perceived challenges of being in sleep debt along with some physiological parameters.

Subjects were forced to go 30 hours without sleep and then complete a treadmill stress test.  They first went for 30 minutes at 60% of their V02max, and then went for 30 minutes as hard as they could.  All of the subjects also completed baseline tests when on normal rest.

The subjects were evaluated using the following parameters: core temperature, skin temperature, heart rate, oxygen uptake, carbon dioxide production, some breathing measurements and rating of perceived exertion.

These are the changes the researchers saw:
  • Less distance was covered after sleep deprivation (by 2.9% on average)
  • Subjects consumed slightly more oxygen during the initial 30 minutes in the sleep deprivation trial
  • There was very little difference in the remaining parameters, including perceived exertion
Practical Applications:

So what does this study show us?  Well, first of all, it points toward the conclusion we all would expect: not sleeping over the course of 30 hours makes you slower than if you were well rested.  

The interesting thing, however, is that there was very little difference in the numerous physiological outcomes that were looked at.  There was a hint of sleep deprivation having a negative impact on cardiovascular physiology (which the authors seem to dispel, I'm not sure why?), but all other measures remained constant.  The authors speculate that the reduction in performance, therefore, was likely due to psychological changes involving how the subjects perceived their level of exertion.

Even though the runners THOUGHT they were going just as hard after 30 hours of not sleeping, they were actually going slower.  Perhaps the lack of sleep lowered their threshold for pain?

Clearly more research is needed.  A next logical step would be to investigate WHY the subjects consumed slightly more oxygen after sleep deprivation despite moving at the same pace.  

That being said, if you are an ultra runner, and you plan on working on limited sleep, this study is nothing but good news for you!  It suggests that your body can keep working while the mind starts to fail.  SO, if you just suck it up, there's a good chance you will be good to go!

Ultra runners (or tired runners)- what are your experiences with running while on no sleep?  Is this study consistent with what you went through? 

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