Abstract
Introduction: The isotemporal substitution model (ISM) is a statistical approach that estimates the effects of replacing, in minutes, a block of physical activity or sedentary behavior by another block with different intensity. Previous studies have used the ISM to evaluate the effect of different isotemporal substitutions on body composition. Thus, the ISM can contribute to the understanding of changes in body composition related to distinct lifestyles and, hence, guiding future recommendations for maintaining and/or improving body composition. Objective: To review the effect of replacing sedentary behavior by physical activity on body composition change analyzed through ISM. Methods: Original articles in English were identified from searches in PubMed and Periódicos Capes databases. The search was carried out by two researchers. Last search was performed in October 2020. Results: A total of 17 included articles, which evaluated different applications of ISM in relation to body composition change, mostly obtained by BMI and body fat. The physical activity was mainly assessed by using an accelerometer. Several methodological differences among the included studies limited comparisons between findings, including the sample profile and cut off points for physical activity. Conclusion: Among the studies that evaluate the effect of replacing sedentary behavior for different intensities of physical activity through ISM, replacing sedentary behavior by moderate-to-vigorous physical activity presented a more consistent effect in body composition change in comparison to replacement by other physical activity intensities, even for small blocks of time (five minutes).
Highlights
The isotemporal substitution model (ISM) is a statistical approach that estimates the effects of replacing, in minutes, a block of physical activity or sedentary behavior by another block with different intensity
Eligibility criteria The eligibility criteria were studies that investigated whether replacing sedentary behavior for the same amount of time of physical activity at different intensities determined body composition change analyzed through ISM
Review, and summarize studies that investigate whether replacing sedentary behavior by physical activity at different intensities determines body composition change by using a specific statistical approach
Summary
The isotemporal substitution model (ISM) was developed after publication of Willett’s nutritional studies[1]. Regarding the ISM, the most used blocks were time spent in watching television, slow and fast walk, running, and other activities (swimming, bicycle riding, aerobics, playing tennis, climbing stairs)[1]. Time spent in these activities generate coefficients to total physical activity[1]. ISM uses absolute values of physical activity (i.e., block of time spent in each activity in minutes instead of percentage) to be more “touchable” and, to facilitate the interpretation. The purpose of the present study was to identify, review and synthesize studies that investigate whether replacing sedentary behavior by the same amount of time of different intensities of physical activity determine body composition change, when analyzed through ISM. We aimed to provide basis for development of behavior change interventions
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