Run Pace Normalising for Hills

So I tore myself away from the Royal Wedding coverage this morning for a 10mile run. This is a specific pace session, with a bit of a warm up then 10mile at 6min/miles. Ordinarily (over the winter at least) I’ve been doing this type of pace run on the treadmill for accuracy. But given the Royal holiday, access to treadmills today was a little limited (and indeed last weekend due to the Bank Holiday weekend too) so I’ve been getting out in the nicer weather and slogging it out on the roads.
The only problem with this is that around where I live is by no means flat. So, I strap on the trusty Global Trainer and head out for the run. With all the data that the GT collects, I did a little web surfing and found this article which suggests how to take into account ascents and descents: http://runningtimes.com/Print.aspx?articleID=10507
The article’s author suggests that treadmill tests show that a 1% elevation means that per mile for a 5min/miler they should allow 10secs more per mile and that a 7:30 min/miler should allow 15 secs per mile more; and this is for every single % per mile. (52.8 feet per mile is 1%)
So this is what I’ve done:
The Global Trainer tells me that I’ve gained and lost (circular route) 1550 feet in total. So that’s 155 feet per mile, and at an estimated flat pace of 6min/mile, this amounts to a 3% grade or 36secs/mile extra due to the climbing. However, we need to add back in the descending – apparently you get back about 55% of the time of the climbs – so as you would expect, you do go slower over a hilly course compared to a flat course. This means that I’m left with a 16secs/mile handicap because of the hills.
My 6:28mins/mile pace through the rollers therefore works out at a ‘normalised’ 6:12mins/mile pace. Given that I was supposed to be running 6min/miles, I clearly slacked off a bit, but not as much as the actual pace suggested.
Its not a bad guestimate at how hills translate into flat pace – the GT data again proves itself invaluable.
But now I’m going to get back to the Royal Wedding highlights!