Saturday, June 18, 2011

Furman hydration tips

With the long winterspring we've had and summer late to arrive (it's not here yet), I've been convinced that summer will hit us all at once, on the worst possible day: Seattle RNR Marathon Day.

It's totally illogical but I've been convinced that the heat will hit on marathon day, giving us NO time to acclimate. And I do NOT do well in heat (heat = > 65 degrees). So, I've planned to wear a white singlet to stay cool, visor to block the sun, 70 SPF sunscreen to protect the skin, etc.

The actual prediction? 60 degrees and rain. Sounds fine to me - or - better than heat anyway. This, I can deal with. I KNOW rain, I know 60 degrees, though even that will feel quite warm once I get going. I don't want a downpour, but a few sprinkles will be fine.

So before this forecast came out, I was doing some reading on the Furman Institute of Running website. They have a great download on HEAT & HUMIDITY. I thought I'd share a few interesting tidbits as I know it will be warming up eventually around here and it's already really DAMN hot in other places. There is much more detail in their presentation so if you're interested, I recommend checking it out.

Consider the effects of heat on your body:
  • Blood flow increases at skin surface, taking blood flow away from your working muscles
  • You experience a decrease in blood volume
  • Your heart rate and body temperature gradually increase
  • Oxygen and glycogen/energy consumption increases
  • All this TIRES YOU OUT
When planning for a race or run, consider both the heat and humidity. The Furman guys give this rule of thumb: If temperature + humidity > 150, be careful! Personally, I think an index of 120 would be good but they're the experts.

What to do when exercising in heat & humidity:
  • Drink according to a schedule, do not use thirst as your guide, and start drinking early
  • Start getting adequately hydrated 24 hours BEFORE your run
  • Drink 0.5 liter about 2 hours before your run (~16 oz.) 
  • Add carbohydrates to water if exercising > 1 hr
  • Consume 500-700 mg sodium per liter of water if exercising > 1 hr
  • Drink COLD water to help cool your body and increase the absorption rate of the water
Interesting that the Furman guys say it takes about 5 to 10 days for your body to acclimate. By acclimatization, they mean your body starts sweating earlier to cool off sooner, blood flow at skin surface decreases (keeps that blood in your working muscles instead), blood volume increases, electrolyte loss decreases, and you burn less oxygen and fuel.

Good stuff.


  1. Thanks for sharing. I am also using the FIRST training program to train for an upcoming half marathon and was looking this up last night!!

  2. We were just talking about the effects of heat and humidity on the run today. Thanks for the info!

  3. So, if I go run in Hawaii again, I will be telling my husband we need to be there 10 days ahead of the race!! Awesome!

    Good advice, thanks.

  4. I just moved to Florida and MISS running in Seattle! (Oh, what I wouldn't give for temperatures in the 60s. I was actually pretty speedy then! Acclimated or not, 90+ temps are killing my pace -- which is not good for my ego.)

    I'm glad to know I'm not the only person who wilts in the head (and that it's physiological, not just me being a wuss).

    Good luck with the marathon next week. I look forward to the post-race report!

  5. I hear ya! I don't do well in the heat either. In fact, I consider heat my own personal Kryptonite.

  6. Thanks for the helpful info! I am worried about a sudden temp spike too, and will probably carry water in the half as a security blanket. Still going back and forth on that decision though.

  7. Great tips! Did you see that now it says partly cloudy and high of 69? Chance of precip: 20%.

  8. Great info! Furman rocks. Praying it doesn't get too hot for you on race day. I am no fan of heat either.

  9. I hate heat. Good luck. Be careful.