Heel kick
How tightly your leg folds during swing
After propulsion the foot leaves the ground and the leg swings forward as it folds: the heel rises toward the glutes. Runify Motion measures how far the knee bends in this phase, for each leg.
Descriptive measure: the app gives you the value and explains it, with no score and no verdict.
Recovery: the knee of the leg swinging forward
How to read the value
0° is a straight leg; the higher the value, the more tightly the leg folds during swing.
It’s a descriptive measure: the app gives you the value and puts it in words, for example “During swing the knee bends to about 117°: how far depends a lot on speed,” with no score.
What it can mean
It grows a lot with speed: at an easy pace it’s normal for the knee to bend less. The value describes how you run; it doesn’t judge it.
Compared with 2.5 m/s, at 3.5 m/s the knee bends on average about 15° more during swing, and at 4.5 m/s about 26° more: a low value on a slow run isn’t a flaw.
Studies: Fukuchi 2017.
To measure it well
Only compare analyses recorded at the same speed: the faster you run, the more the knee bends.
What the app suggests
Nothing to try: the value describes how you run; it doesn’t judge it. Butt kicks stay in the catalog as a technique drill, not as a way to change this measure.