Sedentary behavior: Different types of operationalization influence outcome measures.
Level 4 - case-series / case-control
Cross-sectional comparative measurement study
PubMed 28324755 · doi:10.1016/j.gaitpost.2017.02.025
What was done
Fifty-three healthy participants wore a multi-sensor activity monitor for 24 hours to measure body posture and movement intensity at one-second resolution. Researchers evaluated three operational definitions of sedentary behavior during waking hours: 1) posture and intensity combined (lying/sitting and <0.016g, COMBI); 2) posture only (lying/sitting, POST); and 3) intensity only (<0.016g, INT). Total sedentary time and sedentary pattern metrics (bout count, mean bout length, fragmentation, W-index) were compared across definitions using repeated measures ANOVA.
What was found
Total sedentary time differed significantly across all three definitions (p < 0.001): 505.8 (113.85) min for COMBI, 593.2 (112.09) min for POST, and 565.5 (108.54) min for INT. Significant differences were also found for other sedentary outcome measures, but specific numerical values for those metrics were not provided in the abstract.
Why it matters
Studies measuring sedentary behavior using only accelerometry counts or only posture sensors generate non-equivalent sedentary metrics. Accurately adhering to the formal definition of sedentary behavior requires capturing both posture and energy expenditure concurrently.
Limits
The study evaluated a small sample of 53 healthy individuals over a single 24-hour observation period. Numerical values for secondary sedentary pattern metrics were not reported in the abstract, and clinical outcomes were not evaluated.
Cited by
- context Sedentary behavior is defined as an energy expenditure falling below 1.5 metabolic equivalents (METs).