New Methods to Assess Forearm Torque and Lifting Strength: Reliability and Validity.

Area of Science:

• Biomechanics
• Clinical Measurement
• Rehabilitation Science

Background:

• Objective measurement of forearm torque and lifting strength is crucial for assessing wrist and forearm disorders.
• Existing methods may lack repeatability or validity in clinical settings.

Purpose of the Study:

• To determine the repeatability and validity of new methods for objectively measuring forearm torque and lifting strength in a clinical setting.
• To compare the performance of new dynamometers (Baseline and Kern) against a reference standard (Work Simulator II, Baltimore Therapeutic Equipment - BTE II).

Main Methods:

• Twenty-eight healthy volunteers were tested for lifting strength and forearm torque using Kern and Baseline dynamometers.
• Two raters assessed participants on three occasions, with one rater also testing in a seated position and using the BTE II.
• Intraclass correlation coefficients (ICCs) and Bland-Altman plots were used to assess intra- and interrater reliability and validity.

Main Results:

• Excellent intra- and interrater reliability (ICCs 0.88–0.96) was found for forearm torque measurements with both Baseline and BTE II.
• Comparisons between Baseline and BTE II showed substantial agreement (ICCs 0.74–0.88).
• Lifting strength measurements demonstrated high reliability (ICCs 0.84–0.96) and strong agreement between Kern and BTE II (ICCs 0.91–0.95).

Conclusions:

• The Baseline and Kern dynamometers exhibit excellent intra- and interrater repeatability for forearm torque and lifting strength.
• The new methods are valid when compared to the BTE II, with the exception of forearm pronation torque (ICC 0.74).
• Measurements in standing or seated positions showed minimal difference, indicating the methods' suitability for future clinical studies.