Reliability and Validity of a Low-Cost and Portable Dynamometer: Toward a Simple Clinical Test for Assessing Plantar...

Area of Science:

• Biomechanics
• Rehabilitation Engineering
• Clinical Assessment

Background:

• Plantar flexor weakness is prevalent in neurological and orthopedic conditions.
• Reliable strength assessment tools are crucial for managing these disorders.
• Existing gold-standard devices can be cumbersome for routine clinical use.

Purpose of the Study:

• To evaluate the validity and reliability of a portable strain gauge dynamometer for measuring plantar flexor strength.
• To compare the portable device against a gold-standard instrumented dynamometer.
• To determine the clinical utility of the portable strain gauge dynamometer.

Main Methods:

• Thirty-five healthy adults participated in validation and test-retest reliability studies.
• Plantar flexor maximal force and torque were measured using the portable and reference dynamometers.
• Statistical analyses included Pearson correlations, Bland-Altman analyses, and intraclass correlation coefficients (ICCs).

Main Results:

• A strong correlation (r = .84) confirmed the portable dynamometer's validity against the gold standard.
• The device showed excellent test-retest reliability (ICCs = .889-.926).
• A slight torque underestimation (-4.6%) and acceptable bias were observed.

Conclusions:

• The portable strain gauge dynamometer is a valid and reliable tool for assessing plantar flexor strength.
• Its performance supports its use in clinical settings for evaluating muscle strength.
• The device offers a practical alternative for strength assessment in patients with mobility impairments.