# Comparison of Omron and ActiGraph monitors in estimating daily step counts and time spent in moderate to vigorous physical activity in free-living adults

## TL;DR

This study compares two activity monitors to see how accurately they estimate daily steps and physical activity in real-life settings.

## Contribution

The study provides a direct comparison of Omron and ActiGraph devices in free-living adults using Bland-Altman analysis.

## Key findings

- Omron estimated similar daily step counts but more MVPA time compared to ActiGraph.
- Differences increased with higher activity levels.
- Bland-Altman analysis showed wide limits of agreement for both step counts and MVPA.

## Abstract

This study compared the Omron Active style Pro HJA-750C (OM) and the ActiGraph wGT3X-BT (AG) in estimating daily physical activity—step counts and time spent in moderate to vigorous physical activity (MVPA)—in free-living adults.

Japanese adults without gait abnormalities wore both devices during waking hours for seven consecutive days. Data were aggregated into daily steps and MVPA. A valid day required ≥10 hours of AG wear time with ≥100 and <50 000 accumulated steps from both devices. Agreement was assessed using Bland-Altman plots with multilevel analysis.

The final dataset included 129 participants (age 23–89 years, 50.4% women), totalling 887 observations (5–7 daily observations/participant). OM estimated an overall mean of 7456 (SE 253) steps/day and 68.9 (SE 2.8) min/day in MVPA. Bland-Altman plots showed that OM estimated −56 steps/day (95% limits of agreement (LoA) = −1599; 1486) and +23 min/day (LoA = −17; 63) in MVPA compared with AG. Differences tended to increase with higher mean estimates for both step counts and MVPA.

OM estimated substantially more daily time spent in MVPA but showed similar daily step counts compared with AG. Differences were larger with higher activity levels.