Measuring shoulder abduction strength using 2 different dynamometers: comprehensive intrarater and interrater...

Area of Science:

• Orthopedics
• Musculoskeletal Research
• Rehabilitation Medicine

Background:

• Accurate assessment of isometric muscle strength is crucial for diagnosing and managing shoulder conditions.
• Handheld dynamometers (HHD) offer a portable and accessible method for muscle strength testing.
• Comparing HHD with fixed dynamometers (FD) is essential to validate its clinical utility.

Purpose of the Study:

• To evaluate the intrarater and interrater reliability of HHD for shoulder abductor isometric strength.
• To compare HHD measurements with those obtained from a fixed dynamometer (FD).

Main Methods:

• Twenty-two healthy participants (age >18) were assessed twice by two experienced testers.
• Measurements were taken at 90 degrees of shoulder abduction in the scapular plane using both HHD and FD.
• Intraclass correlation coefficient (ICC), standard error of measurement, and minimal detectable change were calculated.

Main Results:

• Strong correlations were found between HHD and FD measurements for both testers (r=0.772 and r=0.748).
• Excellent intrarater reliability (ICC=0.941) and interrater reliability (ICC=0.889) were observed for HHD.
• The handheld dynamometer demonstrated high validity and reliability in assessing shoulder abductor strength.

Conclusions:

• Handheld dynamometer is a reliable and valid tool for assessing shoulder abductor muscle strength in research and clinical settings.
• Consider a fixed dynamometer if the study population's muscle strength exceeds that of the testers.
• Further research with diverse populations and tester experience levels is recommended.