Physical Activity Patterns Determine Required Accelerometer Days

Researchers from Reykjavík University analyzed accelerometer step-count data from 258 participants and used hierarchical clustering to identify distinct physical activity patterns, publishing results in JMIR Mhealth Uhealth in 2026. They found four short-term and three medium-term clusters (n≥12), with required days to reach ICC≥0.80 ranging 2–6 days (7-day window) and 6–11 days (28-day window). The study implies researchers should tailor valid-day inclusion criteria to sample-specific activity variability.