Influence of thoracic asymmetry on trunk movement patterns during sit-to-stand motion.
Tetsuya Mamizu, Fujiyasu Kakizaki, Tatsuya Sano and 8 others
PMID 41835171WHAT IT FOUND
In healthy men, a more asymmetric upper ribcage went with more forward trunk bending during standing up, and a head that sat further forward at rest did too.
This is a lab finding, not proof that changing posture improves standing.
Key findings
01In the 20 men whose ribcage sat to the left of the pelvis, the thorax rotated further to the left relative to the pelvis during the transition out of sitting (mean angle 1.49) than at the start of the movement (0.69), and the difference was statistically significant.
02Greater asymmetry of the upper ribcage went with a larger change in trunk flexion relative to the pelvis during the flexion phase of standing up.
03The further forward the head sat at rest, the larger the change in trunk flexion relative to the pelvis during the flexion phase; there was no such relationship with trunk rotation.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Only healthy adult men took part, so this tells you nothing about people with pain, weakness or neurological conditions, or about women. Only 3 of the 23 men had a ribcage deviating to the right, so all of the relationship analyses rest on the 20 men with leftward deviation and the authors say detailed analysis of the other group was not possible. Muscle activity was not recorded, so the explanation about which trunk muscles drive the rotation during the transition is inferred rather than measured. The study describes associations at a single testing session, so it cannot show that ribcage asymmetry or head position causes a particular standing pattern, or that correcting either would change it. Participants stood at a speed they chose and the results come from one laboratory session with three trials per person.
Declared interests
The authors declare no conflict of interest, and the paper states no funding source.
The easy way to misread this
Do not read this as evidence that correcting an asymmetric ribcage or a forward head position will improve someone's ability to stand up. The study measured 23 healthy young men at one point in time and found associations only, and the explanation about which muscles are involved is inferred because muscle activity was never recorded.
Summarised by AI from the full paper, without a clinician reviewing it. Check it against the source before it changes what you do. Read it on PubMed →