New assessment of forearm strength: reliability and validity

Area of Science:

• Biomechanics
• Rehabilitation Engineering
• Musculoskeletal Assessment

Background:

• Accurate measurement of forearm strength is crucial for diagnosing impairments and guiding rehabilitation.
• Portable dynamometers offer convenience but require validation against established gold standards.
• The functional doorknob handle design may improve usability in clinical settings.

Purpose of the Study:

• To evaluate the reliability (intra- and interrater) of a portable hydraulic forearm dynamometer with a doorknob handle.
• To assess the criterion validity of this dynamometer by comparing its measurements to those obtained from a Cybex 6000 isometric torque assessment.

Main Methods:

• A methodological study involving 18 volunteers (30 forearms) was conducted in a single session.
• Intra- and interrater reliability were assessed for pronation and supination.
• Criterion validity was determined by comparing the hydraulic dynamometer's readings with the Cybex 6000.

Main Results:

• Excellent intrarater reliability was observed for both pronation (ICC(3,1)=.937-.961) and supination (ICC(3,1)=.923-.968).
• Good interrater reliability was found for pronation (ICC(3,2)=.927) and supination (ICC(3,2)=.847).
• Criterion validity showed moderate agreement, with correlation coefficients ranging from .574-.664 for pronation and .749-.750 for supination.

Conclusions:

• The Baseline hydraulic dynamometer with a doorknob handle demonstrates high intra- and interrater reliability.
• The device exhibits moderate validity when compared to the gold-standard Cybex 6000.
• This portable dynamometer is a reliable tool for assessing forearm strength in clinical and research settings.