Comparison Of ActiGraph Hip Worn And Wrist Worn Activity Monitors For Assessment Of Physical Activity

Accelerometers worn at the hip are used to assess physical activity, but non-wear can limit such studies. Wearing the monitor on the wrist may enhance compliance, but estimates of physical activity levels may not be comparable between hip worn and wrist worn monitors.

Purpose To examine agreement between wrist worn and hip worn accelerometers on physical activity outcomes.

Methods Sixty-four participants (age 21.3 ± 2.4 yrs; BMI 24.7 ± 4.6 kg/m2) wore two ActiGraph GT3X+ accelerometers (on hip and wrist) for two consecutive days. Participants exercised on a treadmill at two speeds to allow development of a regression model to predict wrist activity counts from hip activity counts. Moderate and vigorous physical activity cut-points for wrist worn monitors comparable to established cut-points for hip worn monitors were calculated. These cut-points were applied to the two days of free-living physical activity. Participants also reported their preferences regarding hip and wrist worn activity monitors.

Results Activity counts for axis 1 and vector magnitude were significantly higher for wrist worn than for hip worn monitors (p < .05), although monitor output was significantly correlated between the wrist and hip (r = .74) during both treadmill and free-living physical activity. Minutes of moderate (hip: 46 ± 21 min; wrist 143 ± 51 min; r = .52) and vigorous (hip: 4 ± 6; wrist 16 ± 14 min; r = .83) physical activity were higher (p < .05) for the wrist worn than for the hip worn monitors. More participants felt the wrist worn monitor compared to the hip worn monitor was comfortable to wear when sleeping (65% vs. 52%) and easy to wear while exercising (94% vs. 67%).

Conclusions Activity counts from wrist worn monitors are moderately correlated to counts from hip worn monitors, but cut-points developed to equate minutes of physical activity did not result in comparable estimates of moderate or vigorous physical activity. Compliance may be improved with wrist worn monitors because participants report greater comfort and ease of wear than for hip worn monitors. The moderately high correlations between activity counts from the hip worn and wrist worn monitors suggests future work to accurately estimate minutes of activity from wrist worn monitors could be successful. Supported by ECU Undergraduate Research Creative Activity Grant.