Iliopsoas
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The major hip flexor, made of the iliacus and psoas major; shortening it increases lumbar lordosis.
Detail
The iliopsoas consists of the iliacus and psoas major muscles. Shortening of these muscles increases lumbar lordosis by pulling the lumbar curvature anteriorly, which can produce low-back strain — counter this with strong abdominals. This effect is seen in exercises such as straight-leg raises from zero to 45 degrees and hip flexions with a straight leg. The iliopsoas contracts strongly in sit-ups, particularly if the hip is not flexed. (Traditional straight-leg sit-ups and leg raises work the hip flexors — the iliacus and psoas, i.e., the iliopsoas.)
Key facts
- Composed of the iliacus and psoas major.
- Major hip flexor.
- Shortening increases lumbar lordosis (pulls lumbar curve anteriorly) → low-back strain; counter with strong abs.
- Contracts strongly in sit-ups, especially with the hip not flexed.
Connections
- Hip Flexors — primary group it belongs to.
- Spinal Column (Vertebral Column) — lordosis effect on the lumbar spine.
- Iliopsoas, Lumbar Lordosis & Sit-Up Lower-Back Caution — straight-leg raise / sit-up caution.
Sources
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Educational content only — not medical advice. Always consult a qualified professional for individualized guidance, especially around injury, pregnancy, or medical conditions.