Piriformis electromyography activity during prone and side-lying hip joint movement.
Yasuhiro Morimoto, Tomoki Oshikawa, Atsushi Imai and 2 others
PMID 29410588WHAT IT FOUND
Prone hip extension with the hip turned outward produced the highest piriformis muscle activity in healthy adults.
Side-lying abduction in outward rotation did not show a clear difference. This is lab muscle activation, not patient outcome evidence.
Key findings
01Piriformis EMG activity was highest during prone hip extension with the hip externally rotated, at 69.6 ± 40.6 %MVC.
02In the three prone extension trials, piriformis activity was higher with external rotation than with neutral or internal rotation.
03The three side-lying abduction trials did not show a clear difference for piriformis activity.
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 11 healthy volunteers, and piriformis results were reported for 10 participants. Participants were healthy adults with a mean age of 22 ± 2 years, so findings may not apply to patients with hip, back, or lower-limb problems. The measured outcome was EMG activity, not pain, strength, function, or clinical recovery. Testing was done only in side-lying and prone positions, not standing or functional tasks. The authors discuss possible mechanisms, but the study did not test whether higher EMG activity changes patient care.
The easy way to misread this
Do not read this as evidence that a patient exercise works. It measured piriformis EMG activity in 10 healthy adults in lying positions, not pain, strength, function, or treatment outcomes.