Hip Extension at Push-Off

Why this matters

Hip extension is the workhorse of forward propulsion, driven by the glutes and hamstrings. At toe-off, the powerful posterior chain has finished sweeping the leg backwards and the foot is leaving the ground; this swing-back of the thigh past the line of the pelvis is what actually propels the runner forward.

Two readings live in the same posture:

• The thigh's angle vs vertical (the legacy single-line measurement). This includes whatever forward lean the trunk has, so a runner leaning forward shows a falsely large "extension" even with a stiff hip.
• The trunk-vs-thigh angle (this measurement). This is the true hip extension — independent of trunk lean — because both lines move together when the runner leans, leaving the relative angle pinned to the actual hip joint motion.

What good looks like

At toe-off the thigh has swung 10°–20° behind the pelvic line, with the glutes-and-hamstrings driving extension. The trunk holds a stable forward lean (~5°) throughout — it doesn't fold or whip back during push-off. The next frame of swing recovery shows the thigh quickly returning forward.

Common faults

• Restricted extension (<5°) — usually a sign of tight hip flexors. Watch for anterior pelvic tilt appearing simultaneously: the runner is faking extension by tilting the pelvis forward instead of moving the thigh, which transfers load to the lower back.
• No extension at all (a negative reading) — the thigh is still ahead of the pelvis when the foot leaves the ground, so the hip never even reaches neutral. This is the severe end of the same fault, not a milder one: read −6° as "6° short of neutral", never as "6° of extension".
• Excessive extension (>25°) — uncommon, but seen in runners who over-emphasise the back-kick. Long ground-contact times often accompany.
• Asymmetric L vs R (>4° difference) — typically traces to unilateral hip flexor tightness or glute weakness.

Coaching cues

• Hip flexor mobility — couch stretch, kneeling hip flexor stretch. Anterior pelvic tilt at push-off is the diagnostic for this.
• Glute activation — single-leg bridges, hip thrusts. The angle is gated by how well the glutes engage, not how flexible the hip is.
• Cue: "Push the ground back behind you." Most runners under-extend because they're focused on what's ahead.

Related measurements

• Midstance Knee Flexion — the previous phase. Stiff midstance often pairs with reduced extension.
• Ankle Plantarflexion — the next link in the same kinetic chain. Plantarflexion + hip extension together deliver propulsion.
• Trunk Bend — lateral compensation patterns can mask extension by tilting the whole pelvis sideways.