Methods for Characterization of Day-to-Day Intra-Individual Variation in 24-Hour Physical Behaviors
- PMID: 40329631
- DOI: 10.1080/24725838.2025.2499273
Methods for Characterization of Day-to-Day Intra-Individual Variation in 24-Hour Physical Behaviors
Abstract
OCCUPATIONAL APPLICATIONSWe present methods to characterize individual day-to-day variation in physical behaviors, either by assessing variation in one behavior in isolation or multiple behaviors simultaneously. These methods could be used in future studies to evaluate the health implications of variation in occupational exposures. For example, the method presented for characterizing variation in a single behavior can be used to investigate how day-to-day variation in time spent standing relates to risks of developing musculoskeletal pain. However, it may be that the health risks associated with variation in one occupational exposure (e.g., standing) depend on the variation in other occupational exposures (e.g., sitting). The method presented for assessing variation in multiple behaviors could facilitate the exploration of such research questions. This method could also be used by practitioners to evaluate the effectiveness of interventions aimed to enhance variation in workplaces.
Keywords: Variation; composition; physical behaviors; sleep.
Plain language summary
Background Day-to-day variation in behaviors may have health implications, but methods to characterize variation in 24-h physical behaviors are under-developed.Purpose We present two approaches to characterize day-to-day intra-individual variation in 24-h physical behaviors, either by assessing variation in one behavior in isolation or multiple behaviors simultaneously.Methods Data for this study came from 563 young adult participants in the 22-year-old follow-up of the Raine Study, which had >1 day of valid accelerometer measurements (mean = 5.0 days, SD = 1.9 days). Daily 24-h physical behavior compositions of sleep, sedentary, light physical activity, and moderate-to-vigorous physical activity (MVPA) were measured using hip-worn accelerometers. Variation in daily 24-h physical behaviors was described by calculating two measures: the ‘standard’ coefficient of variation (CoV) for individual behaviors; and the ‘compositional’ variation in all behaviors, which was obtained by calculating a compositional variation matrix for each participant. To aid interpretation, daily times spent in behaviors were visualized for three randomly selected participants within each of the 10th and 90th percentile of the variation measures.Results When assessing day-to-day intra-individual variation using CoV, the largest variation was found in MVPA (CoV= 0.65, SD = 0.30). Likewise, results based on the compositional measure showed that MVPA contributed the most to the total day-to-day intra-individual variation in 24-h physical behaviors. Visual inspection of randomly selected individual’s behaviors across the week showed higher fluctuation in daily durations among those in the highest vs. lowest decile of variation, for both measures.Conclusion Day-to-day behavior variation can be characterized using either a standard or compositional measure. These measures could be used in future studies to evaluate mechanisms and effects of variation, and the efficacy of interventions aimed at changing day-to-day variation. Evidence based on such studies could support effective interventions and guidelines on day-to-day 24-h physical behavior accumulation for improved health.
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