Forward trunk lean

Also known as: forward lean, torso lean

The angle of your torso forward from vertical, measured at midstance.

Why it matters

The right amount of forward lean shifts load off the knees and onto the hips and glutes, but leaning from the wrong joint can create more problems than it solves.

What it means

A whole-body forward lean from the ankles of about 5–10° is associated with reduced knee loading. Lean from the waist (hinging) is a fault — it loads the lumbar spine and reduces hip extension. The lean should come from the ankles, keeping the torso, hips, and shoulders in a straight line, not from bending at the hips.