Two things wrong with this article.
First, squats are a bit hard to define and compare. How many of those numbers were powerlifting-legal "thighs parallel"? Sprinters and well-coached runners-in-the-gym may well be doing quarter squats to stress the glutes and minimize the risk to the back. Recreational lifters may be squatting shallow because they just like the big numbers. I am pretty sure Jenny Meadows' 3xBW squat is not all the way down.
Secondly, if runners are going to pick one lift as their measure, they should DEADLIFT. Reasons:
- it's 100% repeatable and does not allow any cheating.
- back squats use (and tire) your back muscles. Running with a tired back sucks, way worse than running with tired legs, and can lead to other injuries.
- there is a LONG heritage of strength coaches since Percy Cerutty say 2x bodweight is a good target - much below this, you have something to gain, and much above this, leg strength is not the limiting factor on your running.
- posterior chain will do more for your running mechanics and downforce, and interfere less with your training. The deadlift is training your running and jumping muscle patterns.
- safer. Just drop the bar. More ways to get in trouble with a bar on your back.
If you like squatting, do power cleans, light front squats and push presses. Well rounded workout with one bar from the floor, keeps the spine nice and vertical, encourages athleticism.