Naked Science Forum

General Science => Question of the Week => Topic started by: katieHaylor on 29/01/2018 17:47:53

Title: QotW - 18.01.28 - Is it better to walk or run in the cold?
Post by: katieHaylor on 29/01/2018 17:47:53
Trent asks:

The temperature where I live recently hit minus 40. It got me thinking - is it better to walk or to run through the cold air? Should you run to reduce the amount of time out in the cold, or do the adverse effects of moving faster, like wind-chill, outweigh the benefits of getting to your destination quickly?

What do you think?
Title: Re: QotW - 18.01.28 - Is it better to walk or run in the cold?
Post by: Janus on 29/01/2018 18:34:32
From what little I've been able to find, you would likely be better off running.  At -40 and at a walking pace of ~3mph, thewind chill brings the effective temp down to -57.  At a jogging pace of 8 mph, it becomes -63.   At -57 you are just into the temp range where frostbite can start in about 10 min of exposure.  At -63 you are not yet into that range where frostbite can occur in 5 min.  Since jogging at 8 mph will more than cut the time in half vs walking, it should result in less risk (over a short enough distance).
Title: Re: QotW - 18.01.28 - Is it better to walk or run in the cold?
Post by: Bored chemist on 29/01/2018 19:19:29
Running will also mean that you generate more heat so you will keep a bit warmer.
Title: Re: QotW - 18.01.28 - Is it better to walk or run in the cold?
Post by: chris on 30/01/2018 07:43:06
Trent doesn't say how fast he has in mind to move, and the question put me in mind of a topic we discussed a little while back asking "at what point is wind chill surmounted by frictional heating? (https://www.thenakedscientists.com/articles/questions/what-speed-does-windchill-give-way-frictional-heating)."

In the above, the suggestion was that cycling at about 500 miles per hour should provide enough frictional heating against the air to compensate for the wind-chill!
Title: Re: QotW - 18.01.28 - Is it better to walk or run in the cold?
Post by: alancalverd on 30/01/2018 07:44:14
A surprisingly difficult question that has occupied many survival experts!

Running exposes a larger effective area of your body than walking, and makes you inhale faster than the sinus passages can preheat the air. You will generate more heat when running, but core temperature is more important than surface temperature for mid-term survival, so the current advice on immersion in water is to ball up and keep still.

If you have a choice, running into wind will increase your heat loss but only by a factor of V0.16 where V is the sum of wind and running speed, but running downwind will also reduce the likelihood of facial and tracheal frostbite.

The two schools of thought are exemplified by skiwear. Nordic cross-country skiers rely on speed for survival, so wear thin knee breeches and a windproof jacket with very little insulation - major problem is actually getting rid of body heat
when skirenning at -40 C. Compare this with downhillers' "padded everything" even at -2 degrees.
Title: Re: QotW - 18.01.28 - Is it better to walk or run in the cold?
Post by: katieHaylor on 09/02/2018 10:02:35
This question has now been answered in our show, and you can listen to the answer here:

https://www.thenakedscientists.com/articles/questions/cool-runnings-does-sprinting-or-walking-conserve-more-heat-cold (https://www.thenakedscientists.com/articles/questions/cool-runnings-does-sprinting-or-walking-conserve-more-heat-cold)