Trunk lean
How you carry your trunk as you run
Your trunk is never perfectly upright while you run. Runify Motion measures how far it leans, from hip to shoulder, across the whole clip.
Descriptive measure: the app gives you the value and explains it, with no score and no verdict.
Absorption: the line from hip to shoulder
How to read the value
0° is an upright trunk; the higher the value, the more your trunk leans forward. A negative value means it leans slightly back.
It’s a descriptive measure: the app writes, for example, “The trunk leans forward about 5° throughout the run,” with no score.
What it can mean
A slight forward lean takes some load off the knee and puts more on the hip. There’s no threshold that fits everyone: it depends on speed and style.
A perfectly upright trunk isn’t a goal: studies on lean describe work shifting between knee and hip, not a position to reach.
Studies: Teng and Powers 2014.
To measure it well
Your trunk changes with speed and slope: to compare two analyses, record on the same stretch at the same pace.
What the app suggests
Nothing to try: the value describes how you run; it doesn’t judge it.