Heel contact in elite sprinters

Do elite sprinters touch the ground at all (at top speed) with their heels or do they run only on the balls of their feet???

all sprinters from amature to elite strike first with the ball then as the body passes the GOC/BDC the heel will touch briefly.i have seen only a few sprinters who do not touch with the heel at all and they include marion jones/carl lewis but there are alot more.

So would you say the reason a sprinters heel doesnt touch, is because of superior strength levels to those who do make heel contact???

They said the same thing about Ben not touching but I’m not really sure. I imagine it depends on whether the athlete iin question is fully upright towards the end of the 100m or still slightly forward up to 60m when viewed.
(The study of Ben was taken during a 50m WR race so hard to know what to make of it.)

I would say almost all male 100m runners hit the ground with the ball and heel when running hard.

However, when running easy, most runners run on their “toes”.

I’ve studied some slow motion videos on Asafa Powell and in some races he has heel contact at the end - and in some races he doesn’t.
I think heel contact at the end means he’s still pushing hard / trying to run fast. However, it’s easier to maintain speed if you run easy.

Haven’t watched much female videos, but as they reach max v. faster they have a longer phase of speed maintenance, thus it looks like most females run on “toes”.

Simone Collio (6.55 breaking an old NR this week end) sprints very high , his heel is probably the highest on the circuit. Asafa on the other hand sprints flat footed, incl in the max speed intervals. What to conclude? Both of them touch down very close to bdc and hips stay high with little knee flexion during stance achieving triple extension which is what he are looking for really.

Is excessive knee flexion an indicator of lack of posterior chain strength if running technique is good?

If there is too much flexion then technique is not good. Technique can’t be separate from strength. If an athlete has a bad technique, one question one might ask is Does he have the physical abilities to do better (strength, flexibility, agility, medical situation?). Besides lack of leg strength, could be touch down too far ahead verical projection of COM which causes too long support phase.