Reliability of the intelligent stretching device for ankle stiffness measurements in healthy individuals

BackgroundA number of devices have been developed to measure joint stiffness. This study investigated the reliability of the Intelligent (Intel) stretch device to measure bilateral ankle joint stiffness during passive range of motion (ROM).MethodsThe reliability of the device was investigated based on torque and angle by establishing the consistency of measurements between examiners on different testing days. In addition, demographic variables were analyzed to investigate the degree of stiffness. Forty-six gender-matched subjects completed the test.ResultsThe reliability ICC2,1 coefficient of ankle stiffness between-day for both examiners was 0.77 for the right ankle and 0.76 for the left ankle with a 0.05 standard error of measurement (SEM) for ankle stiffness for the right side and 0.04 for the left side. The ICC values of the two examiners were also high based on Chronbach's alpha (0.87 and 0.86). Among the demographic variables, gender (F = 35.25, p = 0.001) and body weight (F = 23.55, p = 0.001) were the most important factors in determining ankle joint stiffness.DiscussionThe results of this study indicated that dorsiflexion and plantarflexion measurements obtained by the Intel stretch device are reproducible and consistent. In addition, ankle stiffness was significantly different based on gender and body weight to develop and/or maintain ankle function. These results may help to identify ankle stiffness factors that will lead to more efficient rehabilitation programs and injury prevention strategies.