Development and Prospect of Isotemporal Substitution Model in Physical Activity Research: A Narrative Review

Abstract

Human health promotion is an important research field in sports science and public health. Several studies have investigated the association of physical activity, sedentary behavior, and sleep, with various health outcomes in isolation, yet the timing of different behavioral activities within a limited 24-h day is dependent on each other. The proposal of Isotemporal Substitution Model (ISM) research method finds the best time allocation method to maximize health benefits by reallocating the time use of each activity behavior. A literature search was conducted using major computerized databases and library holdings for peer-reviewed articles. The inclusion of articles followed a three-phased approach using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The studies included in this review were divided into three categories. The first category uses qualitative research to sort out the concepts related to ISM and PA, the second category uses quantitative research to review the application of ISM in PA research along the time line, and the third category describes current human 24-h activity measurement tools. Finally, the controversial points of the current ISM research and suggestions for future research development are discussed. Through literature review, scholars are suggested to improve the following research in the later research: standardize the definition and application of ISM; consider human 24-h activity behavior in a more specific manner; establish an evaluation and monitoring system for ISM research in human activities; develop convenient and scientific human activities. The evaluation tool of ISM; in-depth research and discussion on the dose–response relationship of ISM.