++ don't overstride
To go faster increase your cadence
count steps 1 2 3 4
get it down to 12341234
Your knee should give a little at footstrike
Too much is asking for knee trouble
A locked knee may be too harsh
If problems persist and you have $$$ to throw at the problem
check out Hoka One One shoes
they're not typcial raised heel padded running shoes, more like a flat shoe that's very cushioned.
I've only had mine a week and a half but they're seeming near-miraculous so far.