The Validity of a Portable Strain-Gauge Apparatus Versus a Commercial Isokinetic Dynamometer for Evaluating Knee Extension Kinetics.
Dustin Oranchuk, Chris Juneau, Shelley Diewald and 2 others
PMID 38439775WHAT IT FOUND
For healthy adults, peak force and peak rate of force development were closely matched on a portable strain-gauge plinth and an isokinetic dynamometer.
Rapid-force measures were less interchangeable, so switch devices only for peak force and peak rate of force development.
Key findings
01The plinth strain-gauge and dynamometer produced no significant differences for peak force, peak rate of force development, RFD 2080, or IMP 2080.
02Peak force and peak rate of force development showed very large correlations between devices (r=0.77 and r=0.73).
03RFD 2080 and IMP 2080 showed small or moderate non-significant correlations between devices (r=0.48 and r=0.59).
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Only 14 healthy university participants were studied, so findings may not apply to clinical patients, athletes, or people with knee pain or prior knee surgery. Only the right leg was analysed, and all participants reported right-leg dominance, so left-leg results are unknown. The study compared a single isokinetic dynamometer and a single strain-gauge, so results may not transfer to other devices or manufacturers. The small sample made it hard to judge device bias in high performers or low performers. Pre-tension, self-selected rest, and combined maximal and rapid contractions can add variability, making small changes hard to trust. Single-joint isometric testing may need to be used alongside dynamic multi-joint assessments.
Declared interests
Some authors helped develop the strain-gauge and software, with the end goal of commercialization.
The easy way to misread this
Do not conclude the strain-gauge is interchangeable with the dynamometer for all knee-extension kinetics. RFD 2080 and IMP 2080 had non-significant correlations and greater differences in high performers, so those measures should not be compared across devices.