Reliability and concurrent validity of Iphone®level application for measuring lower limb active flexion and extension range of motions in physical education students

Background and Study Aim. The aim of this study was to analyse reliability and validity of accelerometer-based Iphone® Level application for measuring lower extremity active flexion and extension joint range of motion. Material and Methods. Thirty physically healthy students enrolled in sport sciences (11 males, 19 females, 21.2±1.5 years, Body mass 64.4±10.0 kg, Height 1.68±0.8 m, Fat percentage 21.2±7.8 %, 22.5±2.6 kg/m2) participated in the measurements of hip, knee, and ankle joint range of motion twice through Universal goniometer and Iphone® Level applications. The same experienced measurer carried out blind study of plantarflexion, dorsiflexion and knee flexion/extension, hip flexion/extension joint range of motion three times for each measurement methods and the other researcher recorded the results. For simultaneous validity analysis Pearson coefficient of correlation was used to decide the level of adaptation between the two intraclass correlation coefficient and Cronbach’s alpha values. Bland-Altman graphics were utilized for level of agreement between these two different methods. Results. The results of Pearson coefficient of correlation analysis revealed a positive correlation between the measurement values of joint range of motion performed through Universal goniometer and Level App (r2 = 0.44-0.94, p <0.05). Bland-Altman graphics showed a good agreement among Cronbach Alpha values and intraclass correlation coefficient in the confidence range of %95, and universal goniometers and Level App application. Conclusions. The results of this study revealed that goniometric measurements using Iphone® Level App is a good reliable method for measuring lower extremity active range of motion compared to universal goniometer.