AGREEMENT OF STEP-BASED METRICS BETWEEN ACTIGRAPH AND ACTIVPAL ACCELEROMETERS IN ADULTS 18 - 65

Step counting is a simple and widely available method of physical activity (PA) assessment. The 2018 Physical Activity Guidelines Advisory Committee concluded that more research examining stepping intensity, measured as cadence (steps/minute) is needed, including studies examining agreement between different measurement devices. PURPOSE: To compare steps and step cadence variables measured from two research-grade accelerometers: The ActiGraph (AG) and ActivPAL (AP) in a sample of adults. METHODS: Thirty women (n = 18) and men (n = 12) aged 18 – 65 years (29 ± 14 years; BMI = 24 ± 4) underwent 7 days of PA assessment while wearing an AG and AP. The AG was worn on the right hip and the AP was worn on the right thigh. Subjects completed a sleep log to document in-bed and out-of-bed times. Paired sample t-tests, mean differences, and mean absolute percentage error (MAPE) values were calculated for step-based metrics. RESULTS: Step counts per day were lower with AG (9832 ± 3302) compared to AP (10680 ± 3173, P < 0.001), with a mean difference of 848 and MAPE of 9.9%. Mean minutes of 0 cadence were also lower with AG (511 ± 79) compared to AP (627 ± 74, P < 0.001), with a mean difference of 116.3 and MAPE of 19.6%. Mean peak 1-minute cadence (128 ± 18 and 127 ± 12 for AG and AP, respectively) and mean peak 30-minute cadence (106 ± 23 and 109 ± 14) did not differ between devices. Mean differences were 1.0 and 2.8 and MAPE was 4.2% and 7.7% respectively. Mean minutes of cadence between 1 – 19, 20 – 39, 40 – 59, 60 – 79, 80 – 99, and 100 – 119 were significantly different between devices (P < 0.001), with MAPE ranging between 17.7% and 23.4%. Mean minutes of cadence >120 did not differ between devices (14 ± 19 and 15 ± 20 for AG and AP respectively). CONCLUSION: Compared to the AP, which is worn continuously for 24 hours straight, the AG underestimated daily step counts and at cadence rates >19 and at 0. Peak cadence rates for 1 or 30 minutes and cadence >120 did not differ between devices. Reasons for discrepancies across the different metrics are unclear, however discrepancies at low or no cadence likely are due to differences in how sleep and wake time are quantified between devices. Supported by: James Madison University College of Health and Behavioral Studies Research Grant Award