Running when it's hot and (especially) humid
August 10, 2007 7:15 AM   Subscribe

It's not the heat, it's the... you know. Tips on running in high humidity?

Here in Ohio we've been having killer heat. But I still need to keep training for the marathon in October. During the week I suffer the treadmill but once a week I have to run long, and that means outside. We've been in the upper 90's with ungodly humidity for weeks now.

This morning I went out at 8:30 am thinking I would be ahead of the heat. It was already 75 degrees but oh. my. God, the humidity! I planned to run for 90 minutes but I was whipped at 50. I had water and drank plenty before and during. But I felt like such a loser for not being able to make it further.

What about the high humidity saps your energy and strength so much? Should I be breathing differently? My legs felt heavy and it was one of the worst runs I've ever had.
posted by I_Love_Bananas to Sports, Hobbies, & Recreation (21 answers total) 8 users marked this as a favorite
Have you tried using Gu or other portable electrolyte/carbohydrate replacement packs?

You may be better off going even earlier in the morning that 8:30. Think sunrise, before the sun's had a chance to start putting the moisture in the air.
posted by Anonymous at 7:25 AM on August 10, 2007

Response by poster: But when I looked at a weather chart for today, the early morning had the highest humidity levels. ??

My tradeoff was to go for the time when temps were coolest. 8 AM said 75 degress and 93% humidity. Later in the day it was only 62% humidity but a temp of 90+, so I opted for the first choice.
posted by I_Love_Bananas at 7:31 AM on August 10, 2007

Response by poster: And I forgot to mention- yes, I use Gu whenever I run more than 4 or 5 miles at a time.
posted by I_Love_Bananas at 7:33 AM on August 10, 2007

Same problem here in DC. By the time you're running that marathon, the fact that you had to get up and go running at 5 a.m. a few times (I'd do schroedinger one better and say hitting the trial before sunrise is essential) won't seem so crazy.
posted by kittyprecious at 7:44 AM on August 10, 2007

Response by poster: I guess what I am still looking for is information on what is happening physically when the humidity is high, and what I might do to compensate (other than run at a different time of day, which due my schedule is sometime not very negotiable).

Am I bringing in less oxygen with each breath due to the fact that the air is so saturated with moisture? Is sweat evaporating more slowly in the "wet" air?
posted by I_Love_Bananas at 7:50 AM on August 10, 2007

I've been running lunchtimes in downtown Philadelphia for the last few weeks and it's been equally hot and humid. Here's a few things I do:

I drink water, a lot, and hours ahead of time. I also stay consistent so as to acclimate myself. Finally, I make sure I run by a couple of fountains and on extremely hot days, stop, dunk my shirt, wring it out and don it again wet to cool me while I run.

Oh, and you might considering altering your route so you stay relatively close to your home base. That way if you get out and feel really rotten, you're not that far from home if you need to cut it short and rest.
posted by lpsguy at 7:55 AM on August 10, 2007


It's the second one. When it gets more humid, the air is already saturated with water, so it won't evaporate as much of the water on your body. This means your body can't cool itself.

Not sure, but I think you should be getting about the same amount of air.
posted by kingjoeshmoe at 8:11 AM on August 10, 2007

It's your latter point that's correct, bananas. We cool by evaporating sweat, and the humidity prevents that from happening.

If you can't avoid it entirely, you're better of acclimating to it. Just get out in it and survive a few times and the next time won't be so bad. When your marathon comes, it's either going to be in equally horrible weather in which case you'll be damned glad you spent time acclimating, or it'll be in much nicer weather in which case you will feel god-like due to your preparation.
posted by Wolfdog at 8:11 AM on August 10, 2007

When I ran cross-country in high-school my coach never had advice for us on hot days except to brace ourselves for suffering. And hydrate. Honestly, if I were you I would just run at night. I know you think it's the humidity, but a humid 70 degrees has never bothered me. Whereas you cannot run when it's 90 degrees out.

You can't breathe differently, you can't swing your legs differently...nothing.
posted by creasy boy at 8:19 AM on August 10, 2007

Although now that I think about it, obviously you should run as naked as possible, and....could you rig up a system of putting ice under your hat? With slow-trickle mechanism? Or is this crazy talk?
posted by creasy boy at 8:24 AM on August 10, 2007

Best answer: Nthing the explanations for why exercising in humidity sucks. As for planning your runs, maybe pay attention to the dew point, since my understanding is that provides a better absolute measure of humidity in some ways than, uh, relative humidity.

But there's only so much you can do, really. When the dew point is in the 60s and 70s, as it is now in Ohio and Western Pennsylvania (my location), it is just infernal.

Stay hydrated. Weigh yourself immediately before and after exercising, so you can develop a more precise understanding of what your water requirements are, so you don't err on either side.
posted by chinston at 8:36 AM on August 10, 2007

Best answer: Found a pretty neat Heat/humidity index chart. The link has some extra tips on running when it's hot.

Oh and I found something interesting. This
paper (sorry, it's stupid word doc) claims that at least in conditions similar to yours the time of day doesn't really matter.

Bikers and rowers sometimes wears ice vests but I wouldn't run in one.
posted by uandt at 8:40 AM on August 10, 2007

Can you run indoors, on a treadmill?
posted by futility closet at 9:16 AM on August 10, 2007

What do you wear? For high humidity, you want something that really wicks the sweat away. Skin-tight underarmor is great for this. Since the air itself is too saturated to evaporate much sweat, the underarmor helps by wicking it off your skin, cooling you. It still isn't the best solution, but it works for me when I have practice or have to run decent distances.
posted by Loto at 9:30 AM on August 10, 2007

Response by poster: uandt, that chart and article are great- very helpful!

From the linked article:
"While running, your body's demand for oxygen to the muscles means less blood will flow to the skin and this is when overheating occurs.

"And thus begins the tug-of-war within your body, especially if you want to keep up a certain pace. Either the blood (and oxygen) goes to your muscles to keep up with the pace demands and you start to overheat because less blood is going to the skin for cooling - OR - the blood goes to the skin for cooling, but less blood goes to your working muscles meaning you'll be forced slow down. "

She also states: "It takes approximately two weeks of consistent running in the heat and humidity to acclimate to warmer conditions. " Ugh. But I guess if that's what it takes. I'm bummed that the weather seems to be putting the brakes on my training plan, but oh well.

Futility closet, I do use a treadmill for shorter runs but it's so godawful boring... plus my gym gets frowny if you stay on a machine as long as I would need to for these runs. And since the marathon is outside, I want my long runs to be as close to those conditions as possible.
posted by I_Love_Bananas at 9:31 AM on August 10, 2007

If you're training for a marathon, hopefully, you've given up on wearing cotton shirts or the like. I find there's nothing more refreshing that running in a nice technical tee that's drenched in cool water. Sometimes, it comes from running through a sprinkler. Sometimes, it's just me squirting water from my water bottle over my head.
posted by advicepig at 9:35 AM on August 10, 2007

I deal with the heat a lot out here in AZ and every summer seems to bring a new level of brutality. Sucks!

I just did the SF marathon two weeks ago, so I spent a substantial portion of the summer training.

Mostly, I just end up running really, really early in the morning, like around 5:00 am, right as the sun comes up. When I miss my early morning wakeup, though, I usually end up in the pool as an alternative. Not as fun as running, maybe, but a totally nice alternative to the tyranny of the treadmill... plus, I've found that the increased core strength I've gotten from swimming has helped immensely with my marathon times.

What marathon are you doing?
posted by ph00dz at 9:53 AM on August 10, 2007

Best answer: I've actually found that running somewhat *after* the heat of day - six PM or so - is best, specifically because of the humidity. The "humidity" that is listed on the weather report is actually *relative* humidity. Warmer air can hold more humidity, so a specific dew point (temperature at which the current absolute humidity would be 100% relative humidity) might correlate to 90% when it's 77degrees, and only 60% at 95F. When the RH is above 80% or so, I feel like i'm suffocating; even though the temperature was a hellish 98 here in St. Louis yesterday, that the RH was down (because it was so damn hot) made running almost bearable.

Nonetheless, try to plan your run to go by or through parks that have drinking fountains, just to get a few sips, plus the shade. Also, load up with a quart of liquid about an hour before you run, and then start your run right after the *second* time you pee.
posted by notsnot at 9:55 AM on August 10, 2007 [1 favorite]

Response by poster: @ ph00dz: it's the Columbus Marathon.
posted by I_Love_Bananas at 2:13 PM on August 10, 2007

Like the op, I want all of my miles to be outdoors miles. In fact, I haven't been on a treadmill in at least 2 years. Five miles on the treadmill? Okay. A 15 miles on the treadmill - not even for love or money. I'm also constrained in when I can train. Unfortunately, many days it's in some pretty intense humidity.

The humidity prevents your body from cooling efficiently. Anything you can do to keep yourself cool will make your run better. On especially muggy days I use a capbandoo hat to use evaporative cooling. On the worst days, I use the neck coolie thing too.

It's not the sexiest look. I may look like a dork, but I'm not passing out from heat exhaustion.
posted by 26.2 at 11:36 PM on August 10, 2007

Also, water vapor displaces oxygen, but I'm not enough of a sci-geek to figure out the extent.
posted by BrotherCaine at 6:21 AM on August 11, 2007

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