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

Objective: 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.

Methods: 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.

Results: 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.

Conclusion: 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.