Monday, July 9, 2012

Outrunning The Heat - How To Survive The Next Heatwave

If you are living pretty much anywhere in the US, you've experienced a massive heatwave over the past 10 days or so.  In DC, we've had 10 straight days of 95+ degrees!  But fortunately, with a cold front that blew through last night and this morning, that streak will be broken...phew!  It has been brutal and extremely frustrating as an endurance athlete.

The big question everyone seems to ask is what can I do to acclimate?  Well this can vary from person to person and it also depends on the extent of the heat.  Your body will amazingly adjust to any set of conditions, but hot is always going to feel hot.  Its just a matter of how efficiently your body will operate in a given set of conditions that we can control.  With effective heat acclimatization we can do a number of things that will drastically improve our chances of a better experience:
  • Have a better control of our body temperature
  • Sweat sooner and increase the number of activated sweat glands
  • Increase blood volume
  • Ensure more blood is available to the muscles
  • Lower the increase in your heart rate

If you can survive the temperatures, it can really work in your favor to soak up the extra hours of the summer and make the most of that extra time.  Around these parts, light remains outside till around 9 pm, which is a drastically different case than the winter, when it gets dark around 4:30 pm.  So needless to say, I like to make the most of my summer by getting outside wherever possible.  And specific to running, that means implementing a strategy that not only WORKS, but doesn't leave you feeling like death at the end.

So with the latest increase in temperatures, you may have seen an uptick in the number of articles/blog posts about surviving the heat.  Unfortunately, many of them leave much to be desired, because they are simply a set of generic advice you could find anywhere.  This motivated me to write something specific, because I don't find generic articles very useful.  In those articles, you'll find such blah advice as:
  • Run in the cooler part of the day - For some people who have flexibility, this is a viable option, but not everyone.  And certainly when it is already in the 80s with 80% humidity at 5 am, there is no "cooler" part of the day.  Right now, my schedule is based on when I can get out - whether that is at 12 noon, or 5 am.  So it doesn't matter if I want to run when it is cooler - sometimes I just have to make due with whatever is available.  And many other people with real lives deal with the same situation.
  • Hydrate - This is the most common thing you see people say, but rarely do they tell you any guidelines.  How much?  What should you drink?  Does the duration/intensity of your run matter?  When should you hydrate?  It frustrates me to not end that people give "advice" that simply says to hydrate well.  Based on anecdotal evidence I've seen at larger races, many people have more problems from over-hydrating than from dehydration.  This doesn't mean everyone suffers from hyponatremia, but often times people do get mild cases of it by simply drinking too much water and diluting their balance of electrolytes.  Dehydration happens to everyone and has even shown that  faster runners were more dehydrated than slower runners at the end of a marathon.
  • Go slow - Ok, so some people get it that it is harder to run in the heat, but how slow should you go?  Often times, you'll read advice to run by feel in these situations, but the problem I see with most runners, is that their judgement at the beginning of a run is drastically different than how things feel 45 min to 1 hr into a run.  So what happens?  They think they are going slow, but because of a certain pace they were running early on, their mental spirit comes crashing down when they realize it is either too hard to keep that pace or they keep the pace and work much harder to maintain it.  Either way is not an ideal scenario and it leaves you frustrated, questioning your fitness.
So with these thoughts in mind, I'd like to propose at least 1 SPECIFIC strategy for surviving the heat - the one that it seems most people struggle with - How To Adjust Your Pacing.

Adjusting Your Pace

Notice above when I mentioned that running by feel often results in not dialing in the right pace for these hotter runs?  Well what happens is that your body isn't working as hard to cool itself early on, so most of your body's resources are going to support your running.  But once you've established an increased core temperature from working out, your body's resources start doing damage control to cool itself.  You sweat more (hopefully) and things start to feel more difficult as the run gets longer and your body works to keep up with the demand.  This is because less blood is actually going to the muscles to support your running, since it is also being used to cool you.  This is why it is harder for you to maintain the same pace you set out at.  So even though it felt slower to start, it can quickly make you realize that it wasn't slow enough.  And if you use a heart rate monitor, you'll also notice this trend.  If you maintain your heart rate for a given "zone", you'll end up slowing considerably over the course of a run to maintain the same heart rate.  Partly due to cardiac drift, but also due to your body's response to try and cool itself. 

So what can we do to specifically find out the appropriate pace so we finish our runs feeling strong?  Well, I'm glad you asked!  Nearly every dedicated runner is well aware of the various pace calculators out there, whether you use Jack Daniels vDOT or the McMillan Calculator.  But the problem that most runners fail to consider is that ALL paces in these calculators assume ideal conditions.  And for those that don't know what that is, that means relatively flat terrain and about 55 degrees (sure sounds nice right about now, huh?).  So when you see a range of paces that you should be training at (which I hope is based on a recent race result, not a pie in the sky goal time), it doesn't simply mean you hit those numbers at all costs. 

The general guidance here is that you need to slow your running pace by about 3-5s/mile for every 5 degrees above 55F.  So for someone who regularly runs 10:00/mile and is now running in 85F, that means slowing your pace to about a range of 10:18 - 10:30 (3-5 x 6 = 18-30s/mile).  And based on the excessive humidity and heat, I'd caution anyone to steer toward the slower end of that range.

So while it may feel super easy to start, your body will thank you in the 2nd half of your run, when you are actually able to be INCREASING your speed, rather than slowing down.  As a matter of fact, that is exactly what I did on this weekend's long run, by picking up the pace over the last 2 miles, despite running in 90F for nearly 1:30.  I finished the run feeling hot and tired, but I knew I paced it right by slowing down 30-40s/mile, except for those last 2 miles.

Other Helpful Tips
Just a couple of other notes about heat acclimatization I wanted to mention.  In order to maximize your adaptations, you'll typically need 5-10 hr+ runs in the heat.  Within that time, cardiovascular adaptations will start within the first 3-5 days and sweating changes may take up to 10 days to occur.  When starting out, reduce the intensity of your runs initially - so as to give your body adequate time to adjust before overloading it by rapid increases due to the enhanced workload of higher intensity workouts.

So while it may take a bit of self control and an ego check to run slower than you are used to, a runner who dominates their runs is always going to be more motivated to get back out there than the one who slogs through the last few miles of a death march.  You get to choose which option you want to take, so choose wisely.


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