Relationship between iliopsoas muscle thickness and hip angle during squats in different pelvic positions.
Ryo Miyachi, Miyuki Deguchi, Yuki Nishi and 2 others
PMID 33935360WHAT IT FOUND
In seven healthy men, squatting with an anterior pelvic tilt linked iliopsoas muscle thickening to hip flexion.
Posterior tilt squats showed less hip movement and no such link. This suggests active iliopsoas engagement supports hip-dominant squatting, but evidence is preliminary.
Key findings
01Iliopsoas muscle thickness change during squatting was significantly greater in the anterior pelvic tilt position than in the posterior tilt position.
02Only in the anterior pelvic tilt position was there a significant positive correlation between iliopsoas thickness change and hip joint angle change.
03Hip flexion angle during squatting was significantly lower in the posterior pelvic tilt position compared to neutral and anterior tilt positions.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study included only seven healthy males, making it impossible to generalize to patients with pain, disability, or different body types. Muscle thickness change was used as a proxy for muscle activity, but the authors state this does not directly reflect activation and can be influenced by other factors like myofascial extensibility. The pelvic positions were maximal voluntary efforts, which may not represent functional or sub-maximal movements used in therapy. The study did not measure other hip flexors like the rectus femoris, so the isolated role of the iliopsoas cannot be confirmed.
Declared interests
The authors declare no conflict of interest. The work was supported by a JSPS KAKENHI grant.
The easy way to misread this
Do not assume iliopsoas thickness changes prove muscle activity or that these findings apply to patients with low back pain. The sample was small, healthy, and male-only, and thickness is an indirect measure of activation.