Validity Evidence Of Step Count Cut-points To Determine The Moderate-to-vigorous Physical Activity Levels

PURPOSE: The purpose of this study is to obtain step count-based physical activity (PA) estimates collected by wearable devices and compare them with accelerometer PA estimates. METHODS: A total of 59 adults (27 males, 32 females) participated, with 43.12±13.42 yrs (Male : 42.44±13.29, Female : 43.69±13.71) and BMI 23.84±3.25 (Male : 25.91±2.39, Female : 22.01±2.82). In the laboratory, 22 activities including sedentary, low-, moderate-, and vigorous-intensity of activities were performed over 2 hours. Among them, 51 participants wore Actigraph GT3X (AG), fitbit Charge2 (FB), Miband11 (MB), and Galaxy A23 (GP) for a week and then measured free-living activities. The intensity of the number of steps was classified as low≤97, 97<moderate≤119, 119<vigorous≤ 142, 142<very vigorous intensity based on the number of walking steps (Abel et al., 2011). Cohen's kappa agreement was applied to both the lab setting and free-living. Mean Absolute Percent Error (MAPE, %) for the lab setting measurement and Symmetric Mean Absolute Percentage Error (SMAPE, %) for the free-living data set were calculated. RESULTS: In the lab setting, the moderate and vigorous intensity time (minutes) of each measurement based on the number of steps were as follows: AG: 29.69±2.81, FB: 28.57±4.10, MB: 26.00±3.20, GP: 32.36±3.50. The agreement between AG and the estimated PA levels of each device was FB: k=0.847, MB: k=0.715, and GP: k=0.830. Also, MAPE(%) was FB: 10.69±10.55, MB: 13.81±10.04, and GP: 11.69±9.24. In free-living, estimated moderate to vigorous PA time (minutes) for each device was AG: 39.35±40.00, FB: 35.71±39.21, MB: 34.32±34.18, and GP: 37.75±39.86. For agreement with AG, the kappa was FB: k=0.586, MB: k=0.677, and GP: k=0.721. In addition, SMAPE(%) was FB: 14.65±14.55, MB: 12.93±13.36, and GP: 13.86±14.80. CONCLUSIONS: The walking step counts were similar for estimating moderate to vigorous PA in the lab setting, except for GP. Nevertheless, larger error rates revealed to estimate moderate to vigorous PA based on the cut-points of the step counts. This study was supported by Korea Disease Control and Prevention Agency [A2022-0634] Corresponding: [email protected] Korea Disease Control and Prevention Agency