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Exercises

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

stretchhipintermediateHip flexor / iliopsoas length

Content last reviewed: 2026-07-18

4 × 25s

The posture scan does not measure thoracic kyphosis, lordosis, or flat-back posture directly. This exercise may still help mobility and strength that support overall alignment — it is wellness education, not a diagnosis.

An illustration is coming soon. Follow the step-by-step instructions below.

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, use your hands (or a strap) to move the thigh smoothly into the new stretch range and hold ~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 suits larger muscles and requires you to relax instantly the moment you stop contracting; avoid heavy loading right after.

Muscles worked

iliopsoas — anatomical illustration
iliopsoasAnatomical illustration derived from BodyParts3D, © The Database Center for Life Science, licensed under CC BY-SA.
rectus femoris — anatomical illustration
rectus femorisAnatomical illustration derived from BodyParts3D, © The Database Center for Life Science, licensed under CC BY-SA.

Stretches: iliopsoas, rectus femoris

Part of a program

Part of Lower-Body Posture Reset

This exercise is one move. Lower-Body Posture Reset puts it in a plan — so you know what to do, in what order, and how much, week by week.

  • Sequenced & dosed — the right exercises, in the right order, at the right volume.
  • Progresses with you — difficulty ramps as you get stronger, not on a fixed calendar.
  • Personalized — built around the specific limiter actually holding you back.
  • Tracks your progress — see what's working and adjust over time.

Week 1: 3 sessions · ~15 min each

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