Form fundamentals
Knee Flexion at Contact
How much bend your knee has when the foot touches down (~20° is the clinical norm).
What it is
The knee should touch down with roughly 20° of bend — enough spring to absorb and rebound. A nearly straight knee at contact is a stiff, braking landing; a deeply bent one usually means you're sitting low or fatigued.
Why it matters
Straight-leg landings send impact up the skeleton instead of into the muscles. This number, measured exactly at contact, separates a soft landing from a jarring one better than any whole-video average.
How we detect it
We measure the hip-knee-ankle angle at each detected initial contact and report 180° minus it (flexion), median across strides, per leg.
How to fix it
Quiet-feet strides teach the leg to pre-bend before landing. If the knee lands straight AND the shank angles forward, treat it as overstriding and fix cadence first.
Recommended drills
- •Quiet-feet strides (4x80m)
- •Single-leg squats (3x8/side)
- •Cadence work
Run these 2-3x per week. Expect to feel a change in form 4-6 weeks in.