[cgrubb]

7mph is a speed a lot of people can't run. Those are 8 1/2 minute miles. It corresponds to a speed of 26min for a 5k.

This article

  http://www.letsrun.com/forum/flat_read.php?thread=4612823

has some stats for a 5k race. The average time for men was 28min, and only 10% of the women were faster than 26min.

Slower speeds might skew towards women, who naturally live longer.

Another thought is that people who run fast do so over shorter distances, and their volume isn't sufficient to see a health bump.

[nl]

If someone wants to work out these stats properly, Parkrun[1] has an excellent dataset ready for scraping.

Eyeballing [2] 26:00 will get you 93rd out of 300, ie top 1/3rd. That's probably achievable by someone who runs regularly (3 times a week). On [3] it gets you 362/844.

[1] http://www.parkrun.com/

[2] http://www.parkrun.org.uk/aberdeen/results/latestresults/

[3] http://www.parkrun.org.uk/bushy/results/latestresults/

[rodgerd]

12 km/h isn't particularly unachievable. I'm middle-aged, heavily built, run to and from work a couple of times a week and otherwise do no cardio exercise. I've built up to that kind of pace over a couple of years.

[mkempe]

It's easier if you run at that pace for 20 minutes, 3 times a week...