Development and Usability Study of Mobile Physical Fitness Assessment for Lower Secondary Students Aged 13–15 Years

Physical fitness assessment is an essential component of school-based physical education, yet in many schools it still relies on manual recording that is time-consuming and prone to error. This study aimed to (1) develop a web-based application, accessible on computers and mobile devices, to assist physical education teachers in assessing the physical fitness of lower secondary school students aged 13–15 years, and (2) evaluate user satisfaction and the usability of the application. A Research and Development (R&D) approach based on the System Development Life Cycle (SDLC) was employed. The study included 36 physical education teachers from secondary schools in Mueang District, Chiang Mai Province, Thailand, who used the application to record and analyze five physical fitness components—Body Mass Index (BMI), Sit-and-Reach, 30-s Modified Push-ups, 60-s Sit-ups, and the 3-min Step Test—using 1580 student records. Instruments included the developed application, a user satisfaction questionnaire, and the System Usability Scale (SUS); data were analyzed using descriptive statistics. A comparative analysis of the sit-and-reach test showed a high level of consistency between manual assessments and the mobile application, indicating that the system classified students’ flexibility performance consistently with the manual criteria. The mean SUS score was 87.08, exceeding the acceptable usability threshold, although the internal consistency of the Thai SUS in this sample was low (Cronbach’s α = 0.42); participants reported high to very high satisfaction across all evaluation dimensions. The application’s automatic classifications were identical to the manual classifications across all fitness tests analyzed, indicating that it implements the scoring criteria correctly. Overall, the application reproduced the manual classifications and teachers rated its usability as excellent, suggesting that it is a promising and practical tool for physical education teachers in school settings; its effects on recording time and data-entry errors were not quantified in this study.