Biking in 110 degree desert heat?

July 15, 2005 5:05 AM

Exercising in the extreme heat... Bad idea?

Here in Phoenix it gets regularly above 110 during the day, remaining over 100 well into the night.

Now, personally, I run in the mornings when its only like 89 degrees before dawn, but some of my work buddies regularly go out biking in the afternoons, when its well into the 105-112 range.

How bad of an idea is that? They carry water/gatorade, all that kind of stuff and seem to be in good shape... but are they just fooling themselves as to the risk? Does exercising in those conditions do more damage then good, even if they're used to the heat from years of living in the desert?

posted by ph00dz to sports, hobbies, & recreation (16 comments total)

Biking is probably one of the better sports for high but dry temperatures. Your self generated wind coupled with the low humidity helps your body to cool itself more efficiently than in a humid environment with little or no wind. Nevertheless, I would take it easy in such extreme heat, hydrate yourself well with something that will replace your lost electrolytes and cool down properly. A good cool down would be a five to fifteen minute recovery pace at the end of the ride.
posted by caddis at 5:55 AM on July 15, 2005

IANAAT (Athletic Trainer), but as far as I have heard/read/experienced, as long as you stay hydrated and replace lost salts (the latter really only needed in extreme temperatures like you mention), there is no inherent danger to exercising in the heat. But, I really think that is key - the average person is not pro-active enough to "drink before he's thirsty". Often when I ride with people on only moderately hot days here in NY (say, 85F), some don't even bring water with them. Go figure.
posted by ObscureReferenceMan at 6:03 AM on July 15, 2005

Heat, humidity, extreme excercise, sweat, dehydration = heat stroke
posted by webmeta at 6:21 AM on July 15, 2005

I just recently started taking Bikram yoga classes (power yoga done in a room heated to 110 degrees), and while I'd consider myself to be a fairly fit individual, there have been moments during each 90 minute class I've attended where I had to take a break and lie down for fear of passing out.

I think the key for me is keeping my body hydrated, definitely, but also learning to breathe correctly, so that I have enough oxygen to keep my body from giving out and keep me conscious.

I gotta say, though, nothing has helped to tone me up faster.
posted by killjoy at 7:07 AM on July 15, 2005

I agree with caddis. I routinely cycled (mountain and road, 25-75 miles) in 100+ heat when I lived in Southern California. The combination of the dryness and the motion kept it bearable, but also made it potentially dangerous. I would sweat incredible amounts without really being aware of it. When I returned I'd be covered in salt crystals from the evaporated sweat but was never conscious of it while I was riding. I discovered that it was necessary to start out grossly over-hydrated: I'd drink as much as I possibly could (something around 3/4 gallon of water) before I left. Then I'd take three full water bottles (pre-frozen when I remembered) with me, then drink as much as possibly could (again, about 3/4 gallon) when I got back. Without taking these precautions I'd suffer some dehydration symptoms (sore muscles, weakness, irritibility, and orange-brown piss) up to a day later. Here in the East I can barely go outside if it's over 85 because of the humidity but in the West, with some preparation, there's no need to stop cycling. (btw, I never concerned myself with electrolytes (I can't stand those "energy" drinks); just focusing on water seemed to be what was important for me).
posted by tiny purple fishes at 7:08 AM on July 15, 2005

Not a bad idea, as long as people are smart about it. This includes making sure that they get enough fluids, consider electrolyte replacement if they're gonna be out for longer than an hour or so (pills like Succeed!, not drinks). The Badwater Ultramarathon is run through Death Valley each July, and people do fine.
posted by OmieWise at 7:16 AM on July 15, 2005

I never concerned myself with electrolytes

You should, though. I remember reading an NYT story earlier this year about increasing cases of hyponatremia due to overhydrated athlets who didn't concern themselves with electrolytes. They quoted an ER doc who I believe said he had never seen anyone die from dehydration, but he had seen it from hyponatremia. Watch out.
posted by grouse at 8:38 AM on July 15, 2005

You should, though.

I can only speak of my own experience. In that experience, just getting enough (i.e. huge quantities of) water seemed to prevent any problems, problems including, but not limited to, death. Perhaps my diet included enough electrolytes to compensate for any lost through perspiration; perhaps my repeated prayers to St. Sebastian, patron saint of athletics, protected me; maybe I was just lucky. Your blood chemistry may vary. Consult your physician. Not to be used as a flotation device.

These days I carefully avoid any exertion that might lead to perspiration and the only electrolytes I ingest are those naturally occuring in the mint juleps that I drink in the shade of my veranda. Oh, the humidity.
posted by tiny purple fishes at 9:25 AM on July 15, 2005

Isn't phoenix awesome? General answer: As long as you're hydrated your fine. But it's hard to stay hyrdated.

Here's a suggestion: Pedialite. It's for rehydrating kids but it works much better than gatorade on adults too.

Don't forget sunscreen either, because even if you're hydrated you can still burn.

If you want to do it though you can do it safely. I would say: Pedialite before you go out, then a camelback while you're riding and force yourself to drink it down.
posted by propagandist at 9:37 AM on July 15, 2005

Thanks for the input, folks.

Yeah... phoenix is rad, but right around this time of year, I wonder what the heck I'm doing in the middle of the desert.

That said, I've actually come to really enjoy my pre-dawn raids on Papago and South Mountain parks. If you ever wonder what this town would be like if the weather was perfect, the sun isn't mindblowingly bright, and all the people were gone, hit the road at 5:00 am.
posted by ph00dz at 10:20 AM on July 15, 2005

I read a study that seemed to indicate a few things: If you lose a few pounds worth of water in the process of exercising, you are at risk for hyponatremia. It only applies to long distance exercise, like running a marathon or perhaps a 100 mile bike ride. They also determined that drinks containing electrolytes do nothing to increase your body's electrolyte level during the short term, so you can't remedy the situation by drinking gatorade. Drinking too much can result in more sweat which means more loss of electrolytes.

So, it's a balance between hydration and not over-hydrating. Personally I don't do any runs longer than 5 miles so I don't really concern myself with it. I just keep myself hydrated and everything seems to work fine, even in extreme heat.
posted by knave at 11:19 AM on July 15, 2005

When heat and humidity combine to reduce the amount of evaporation of sweat from the body, outdoor exercise becomes dangerous even for those in good shape.

High humidity can kill you. This article describes the heat index used to calculate how dangerous temperature and humidity (combined) are. For example, 95 degree temperature and 80 percent humidity equals an apparent temperature of 136 degrees. Anything more than 130 degrees is considered "Heat stroke imminent."
posted by WestCoaster at 3:21 PM on July 15, 2005

I think there's something to be said for variations in individual physiology.

I can't feel fully limber and warmed up if it's below 85 degrees, personally. At 110 degrees, I feel fabulous biking hard, as long as I have enough water. And that means a LOT of water - a few liters per hour minimum.

But some of my friends insist that their biking is best done in the snowy winter, when it hurts me just to flex my knees and hips.
posted by ikkyu2 at 6:54 PM on July 15, 2005

The only difference is that they need to stay more hydrated than you. They are making themselves more comfortable in the heat.
posted by raaka at 4:32 AM on July 16, 2005

The US Army has some interesting work/rest/fluid intake tables. A slightly less complex summary is at another military oriented website.

I went through Basic Training during a drought and a heat wave in So. Carolina using these guidelines. Despite being a cold loving type, I survived. Others, who didn't follow the guidelines, became heat casualties. The drills said a couple trainees died every year from heat.
posted by QIbHom at 9:37 AM on July 16, 2005

But some of my friends insist that their biking is best done in the snowy winter, when it hurts me just to flex my knees and hips

I can relate. That is why God created liniment. Winter biking is awesome, given proper preparation.
posted by caddis at 8:29 PM on July 16, 2005