PIR / PFS for the Hip Flexors (Iliopsoas & Rectus Femoris)

How to do it

1. In a modified Thomas position (supine at table edge with the test leg hanging into hip extension), take the hip flexors to their barrier.
2. Barely contract the hip flexors (lift the thigh slightly) against light resistance and hold 20 to 30 s for PIR (or 8 to 10 s maximal for postfacilitation stretch).
3. Relax fully; for PFS, the clinician then quickly and firmly moves the segment into the new stretch range and holds ~15 s.
4. Return to rest with full relaxation for ~20 s.
5. Repeat 3 to 4 times into progressively greater hip extension.

Form cues

• Keep the lumbar spine flat - do not let the pelvis tip forward (anterior tilt).
• Tight iliopsoas/rectus femoris are the prime drivers of lower-crossed anterior pelvic tilt and lordosis.
• PFS is for larger muscles and requires the patient to relax instantly on command; avoid heavy loading right after.

Dosage

PIR: 20-30 s hold x3-4. PFS: 8-10 s contraction, 15 s stretch, 20 s rest x4.

Muscles worked

Stretches: iliopsoas, rectus femoris

Target muscles

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