Validity and Reliability of a Modified Seated Athletic Shoulder Test Using a Functional Electromechanical Dynamometer.
Ignacio J Chirosa-Ríos, Dario Martínez-García, Luis J Chirosa-Ríos et al.
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In 30 seconds
This randomized, repeated-measures validation study assessed between-session reliability and concurrent validity of a seated Modified Athletic Shoulder (ASH) test using an electromechanical dynamometer, compared with the traditional prone force-platform test. Thirty-four active university students completed both assessments. The seated test showed excellent reliability across the 180° (I), 135° (Y), and 90° (T) positions (intraclass correlation coefficient = .91-.97; coefficients of variation = 7.25%-11.33%). Forces correlated strongly between devices (r = .77-.87, P < .001), but the dynamometer produced systematically higher readings, so absolute scores were not interchangeable.
Key findings
- Seated dynamometer reliability was excellent across positions (intraclass correlation coefficient = .91-.97; coefficients of variation = 7.25%-11.33%).
- Prone force-platform reliability was good to excellent, with greater variability (intraclass correlation coefficient = .83-.91; coefficients of variation = 12.43%-15.89%).
- Device forces correlated strongly (r = .77-.87, P < .001), but dynamometer readings had a systematic bias of 18-28 N and nontrivial limits of agreement.
Why it matters
Reliable assessment of upper-limb isometric strength can support consistent measurement across testing sessions. A seated dynamometer-based approach may offer a portable alternative to prone force-platform testing, but strong correlation does not mean the devices yield equivalent absolute values. The observed bias and limits of agreement matter when interpreting scores or comparing measurements obtained with different equipment.
What to keep in mind
The study involved 34 active university students, which may limit how well the findings apply to other populations.