Activity Monitors Step Count Accuracy in Community-Dwelling Older Adults

Area of Science:

• Gerontology
• Biomedical Engineering
• Physical Activity Measurement

Background:

• Activity monitors are widely used to assess physical activity in older adults.
• Accurate step count data is crucial for understanding mobility and health outcomes in this population.
• Previous research has shown mixed results regarding the accuracy of these devices in diverse populations.

Purpose of the Study:

• To evaluate the step count accuracy of various activity monitors in community-dwelling older adults.
• To compare device accuracy across different walking conditions, including self-selected pace and controlled treadmill speeds.
• To inform the selection of appropriate activity monitors for research involving older adult populations.

Main Methods:

• Twenty-nine older adults (mean age ~68 years) participated in the study.
• Step counts from three pedometers and an Actical accelerometer were compared against directly observed steps.
• Data were collected during a 200-m walk and treadmill walking at three distinct speeds (0.67, 0.894, and 1.12 m/s).

Main Results:

• No significant differences were found between activity monitor step counts and actual steps during self-selected pace walking.
• At a slower treadmill speed (0.67 m/s), all devices significantly overestimated or underestimated actual steps.
• Specific devices (Omron HJ-112, Yamax SW-200) showed varying accuracy at different treadmill speeds, with some being accurate at 0.894 m/s but not 1.12 m/s.

Conclusions:

• The choice of activity monitor is critical when studying the walking behaviors of community-dwelling older adults.
• Device accuracy can be compromised at slower walking speeds, potentially affecting research findings.
• Researchers should carefully consider the intended population's typical gait characteristics and walking speeds when selecting activity monitors.