Effects of measurement posture and stimulation intensity on the nociceptive flexion reflex (RIII reflex).
Jeong-Woo Lee, Se-Won Yoon
PMID 28626326WHAT IT FOUND
Sitting required less electrical current to trigger the leg withdrawal reflex than lying prone.
However, participants reported feeling more pain in the prone position despite needing stronger stimulation. The reflex muscle response size depended only on how strong the stimulation was, not on the body position used.
Key findings
01The electrical current needed to elicit the reflex was significantly lower in the sitting position compared to the prone position.
02Subjective pain ratings (NRS) were higher in the prone position than in the sitting position, even though the prone position required higher stimulation intensity to trigger the reflex.
03The amplitude of the reflex response was not affected by measurement posture, showing significant differences only based on stimulation intensity.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
The study included only healthy young women, so results may not apply to men, older adults, or people with pain conditions. The sample size was small (30 participants). The study examined healthy individuals, so it is unclear if posture affects the reflex threshold in patients with chronic pain or neurological conditions.
The easy way to misread this
Do not assume that a higher pain report in the prone position means the patient is more sensitive to pain. The prone position required significantly more electrical current to trigger the reflex, so the higher pain scores may reflect the stronger stimulus needed to elicit the response, not a change in pain sensitivity alone.