Validity and reliability of isometric knee extension muscle strength measurements using a belt-stabilized hand-held dynamometer: a comparison with the measurement using an isokinetic dynamometer in a sitting posture.
Masahiro Hirano, Munenori Katoh, Masahiro Gomi and 1 others
PMID 32158074WHAT IT FOUND
Belt-stabilized handheld dynamometry matched the gold standard isokinetic dynamometer in healthy young men, with no significant difference between devices.
In women, handheld scores did not correlate with the reference device. Use handheld strength data cautiously for female patients until further research clarifies the discrepancy.
Key findings
01There was no significant difference between isometric knee extension strength measured by belt-stabilized handheld dynamometry and isokinetic dynamometry across the whole group.
02Handheld and isokinetic dynamometry scores showed a significant positive correlation in male participants but no significant correlation in female participants.
03Intra-rater reliability for the handheld dynamometer was 0.94 overall and 0.93 in men, but dropped to 0.75 in women.
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 only included healthy young adults aged 19 to 22, so these findings may not apply to older patients or those with neurological or musculoskeletal pathology. The lack of correlation in women means the handheld dynamometer cannot be considered a valid substitute for the isokinetic dynamometer in that population based on this data. Trunk stabilization was achieved by the patient's own upper limb support and foot contact rather than straps, which may introduce variability in how well patients maintain the required posture.
Declared interests
The authors declared no conflict of interest.
The easy way to misread this
Do not assume the handheld dynamometer is a valid replacement for an isokinetic dynamometer for all patients. The study found no significant correlation between the two devices in women, meaning handheld measurements in female patients may not accurately reflect their true knee extension strength compared to the reference standard.