Intrarater Test-Retest Reliability of Hip Abduction, Internal Rotation, and External Rotation Strength Measurements in a Healthy Cohort Using a Handheld Dynamometer and a Portable Stabilization Device: A Pilot Study.
Aaron Byrne, Clare Lodge, Jennifer Wallace
PMID 33543077WHAT IT FOUND
A handheld dynamometer with a PVC stabilization device measured hip strength reliably in healthy athletes.
Changes greater than 5.09 N within a day, or 13.41 N between days, likely reflect true strength change rather than measurement error.
Key findings
01Within-day test-retest reliability was excellent for all hip movements, with the smallest detectable change being 5.09 N for internal rotation.
02Between-day reliability was also excellent, though external rotation showed the largest error margin at 13.41 N.
03The testing protocol took approximately 8 minutes to complete, including setup and rest periods.
STILL TO COME
What they foundWhat it means for PTsWhat it means for OTsWhat it means for SLPs
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What it does not show
The study only included healthy, physically active participants, so these reliability figures may not apply to patients with hip, knee, or back pain. The stabilization device was custom-made and has not been validated against gold-standard isokinetic dynamometry. This was a small pilot study with only 18 participants, limiting the generalizability of the findings.
Declared interests
The study was part of a PhD program funded by the President’s Fellowship Scheme at the Institute of Technology Carlow. No financial inducements were offered to participants.
The easy way to misread this
Do not assume these error margins apply to patients with hip or knee pathology. The reliability data comes from a healthy cohort, and the authors explicitly state that the method needs validation in clinical populations before widespread use.