Validation of the Japanese Version of the Rating of Fatigue Scale

BACKGROUND: Fatigue research remains important across a wide range of fields. In Japan, fatigue has become a major social issue, and research using Japanese population data is expected to contribute to both practical interventions and theoretical advances. Although several Japanese scales for assessing fatigue have been developed, brief instruments designed to measure fatigue during ongoing activity are limited. Therefore, this study translated the Rating of Fatigue (ROF) scale into Japanese and examined the validity of the Japanese version (ROF-J). METHODS: First, the original ROF was translated into Japanese and back-translated. The comparability of language and similarity of interpretability between the original ROF and the ROF-J were evaluated. These procedures were conducted between July and October 2024. Second, the face validity and concurrent validity of the ROF-J were examined in a questionnaire survey of 85 university students at Tohoku University, Japan, in October 2024. Third, convergent validity was examined by comparing ROF-J scores before and after physical exercise among 35 university sports team members at Tohoku University, Japan, in November 2024. RESULTS: As a result of the comparison between the original ROF and the ROF-j, the comparability of language and similarity of interpretability were generally within acceptable limits. According to the examination of face validity of the ROF-J, participants generally agreed that the ROF-J measured fatigue, supporting its face validity. In addition, ROF-J scores showed a significant positive correlation with scores on an established Japanese fatigue questionnaire, supporting concurrent validity. The survey for examining convergent validity indicated that ROF-J scores increased significantly after exercise. CONCLUSIONS: These findings indicate that the ROF-J demonstrates adequate validity. The scale provides a brief and practical Japanese instrument for assessing subjective fatigue during ongoing activity and may facilitate both applied fatigue assessment and future fatigue research in Japan.