Maria Haider, Brantley K. Ballenger, Sydni L. Carter, Grant Norman, Stamatis Agiovlasitis, FACSM. Mississippi State University, Mississippi State, MS.

BACKGROUND: Physical activity (PA) and sedentary time in adults with Down syndrome (DS) have been examined with accelerometer cuts-points developed for the general population. These cut-points may not be appropriate for adults with DS because the association between PA intensity and accelerometer output may be altered in this population. This study examined if DS-specific cut-points and cut-points developed for the general population differ in estimating sedentary time and PA levels in adults with DS. METHODS: Twenty-five adults with DS (age 39±10 yrs; 12 men) had PA and sedentary behavior measured by an accelerometer (wGT3X-BT, Actigraph) on their non-dominant hip. DS-specific vector magnitude cut-points developed by our lab (sedentary: ≤237 counts/min; light ≤2166 counts/min; moderate-to-vigorous: ≥2167 counts/min) and cut points by Freedson (sedentary: ≤199 counts/min; light ≤2690 counts/min; moderate-to-vigorous: ≥2691 counts/min) were used to obtain the variables. Differences between cut-points for total and percent of time in sedentary, light, and moderate-to-vigorous PA were tested with two by three (method × intensity) mixed model ANOVA and follow-up dependent samples t-tests. RESULTS: Participants wore the accelerometer for 6.4±1.1 days (4.7±0.8 weekdays; 1.7±0.5 weekend days) for a total of 5540±1364 min or 850±99 min/day. There were significant method × intensity interactions for both total time and percent of time (p<.001). T-tests showed significant differences between methods in total time sedentary (DS: 2677±803 min, Freedson: 2538±776 min; p<.001), light PA (DS: 2193±742 min, Freedson: 2581±855 min; p<.001), and moderate-to-vigorous PA (DS: 102±45 min, Freedson: 64±36 min; p<.001). Percent of time spent sedentary (DS: 49±10%, Freedson: 46±10%) and in moderate-to-vigorous PA (DS: 12±5%, Freedson: 7±4%;) was higher with the DS than the Freedson cut-points (p<.001). Light PA was higher with the Freedson cut-points (DS: 39±8%, Freedson: 46±8%; p<.001). CONCLUSION: Greater moderate-to-vigorous and less light PA levels were observed for adults with DS when using DS-specific cut-points compared to cut-points for the general population. DS-specific cut-points may more accurately assess PA and sedentary behavior in adults with DS. Funding: Mississippi State University Office of Research and Economic Development and I’m An Athlete Foundation

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