Effect of forearm positions on scapular movements and trunk rotation angles.
Yuuki Homma, Takeru Kato, Akito Chiba and 2 others
PMID 37915457WHAT IT FOUND
Changing forearm position during seated trunk rotation significantly altered both trunk rotation angles and scapular movements.
Supination on the rotating side increased trunk rotation and scapular motion compared to pronation, suggesting upper limb position influences trunk mobility.
Key findings
01Trunk rotation angle was significantly different across the three forearm positions, with supination yielding the highest angle (21.0°) and pronation the lowest (17.5°).
02Scapular movements on the rotational side (downward rotation, posterior tilt, external rotation) were significantly greater when the forearm was in supination compared to pronation.
03The authors suggest that physical therapy evaluation and intervention for trunk rotation should consider the interlocking of the shoulder girdle and upper limbs.
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 healthy young males, so results may not apply to patients with spinal or upper limb disorders, or to older adults. Measurements were taken in a seated position with fixed elbow flexion, which may not reflect trunk rotation during functional activities like walking or standing. The mechanism linking forearm position to scapular movement was not directly measured, though biceps involvement is suspected.
Declared interests
The authors declare no conflicts of interest.
The easy way to misread this
Do not assume that changing forearm position will directly improve a patient's trunk rotation range in functional tasks. This study measured kinematics in a controlled seated position in healthy individuals, not clinical outcomes or functional performance.