Repeatability and accuracy of a foot muscle strength dynamometer

Area of Science:

• Biomechanics
• Kinesiology
• Musculoskeletal Research

Background:

• Toe flexor strength is vital for maintaining balance and enabling effective gait.
• Current methods for measuring toe flexor strength and torque lack sufficient accuracy and repeatability.
• A reliable tool is needed to quantify the torque produced by toe flexor muscles at the metatarsophalangeal joint.

Purpose of the Study:

• To introduce and validate a novel device and methodology for quantifying toe flexor torque.
• To assess the measurement accuracy, bias, and repeatability of the new device.
• To establish a standardized protocol for measuring maximal toe flexor torque.

Main Methods:

• Development of a new device to measure toe flexor torque at the metatarsophalangeal joint.
• Evaluation of measurement bias for angle and torque.
• Assessment of the device's reliability and repeatability using the Interclass Correlation Coefficient (ICC) and repeatability coefficient (CR) in ten participants.

Main Results:

• The device demonstrated high accuracy in measuring angle (bias: 0.10°) and torque (bias: 0.07 Nm).
• Excellent reliability and repeatability were observed, with an ICC of 0.99.
• Low bias (-1.13 Nm) and a small repeatability coefficient (CR = 3.9) were recorded for toe flexor torque measurements.

Conclusions:

• The developed device is an accurate and reliable tool for measuring toe flexor torque.
• The proposed protocol provides a standardized method for assessing maximal toe flexor torque.
• Reporting mean bias and CR is recommended for future measurement techniques in this field.