I am trying to get back into this running lark. Last weekend I set off early in zero degrees with no wind and with no particular ambition and was very pleased and even more surprised to do an accidental PB of 29:12 for 6k.
Flushed with success I set out today once it had stopped raining to see if I could repeat it. I very quickly learned that running into a fierce headwind (24mph according to my weather app) not only decimates your time but will simply destroy you if you are foolhardy enough to try to maintain a non-windy time. After just 2k I was so far off the pace and so utterly knackered that I decided to give in.
When I got back I decided to research the effects of a headwind and will now share this with you so you don't make the same mistake. I found the following facts at runnersconnect.net/running-... if you want to read the whole article.
- Running into a wind that is equal to your running speed will add about 12 secs per mile / 7.5 secs per km.
- Oxygen consumption / energy usage increases with the square of the airflow over the body. So, the performance hit of a 10mph wind is four times greater than that of a 5mph wind.
To translate this to my own run today, my normal pace is about 5 mins per km or 12 kph. The headwind was about 24mph = 38kph or approx 3x my running speed. To find the total effect of the headwind we must square this 3x (giving 9x) and multiply it by 7.5 secs per km. 9x 7.5secs = 67secs.
I ran my second km today (the one into the wind that nearly killed me) in 5:22. Subtract the 67 secs wind effect gives 4:15. A fast km for me in still conditions would be about 4:20 so all this theory & maths seems to work pretty well and explains why I was so utterly knackered. What I thought was an appallingly poor pace/time was very possibly a PB once the wind effect is stripped out!
Oh, and in case you are wondering; while a tailwind does aid performance, you only “get back” about half of what you put into a headwind when you turn around and run with it at your back. So if I had been going the other way and had that 24mph wind behind me my time should have been about 33 secs better than my usual time for that km.
Well I find it interesting anyway......