Comparison of physical activity assessed using hip- and wrist-worn accelerometers

• Physical activity can be assessed using accelerometers worn at the hip or wrist.
• In adults, few data exist on how estimates from both sites compare.
• We found that physical activity correlates moderately well between the two sites.
• The most and least active subjects were more likely to be identically classified.

ObjectivesIt is unclear how physical activity estimates differ when assessed using hip- vs wrist-worn accelerometers. The objective of this study was to compare physical activity assessed by hip- and wrist-worn accelerometers in free-living older women.DesignA cross-sectional study collecting data in free-living environment.MethodsParticipants were from the Women's Health Study, in which an ancillary study is objectively measuring physical activity using accelerometers (ActiGraph GT3X+). We analyzed data from 94 women (mean (SD) age = 71.9 (6.0) years) who wore a hip-worn and wrist-worn accelerometers simultaneously for 7 days.ResultsUsing triaxial data (vector magnitude, VM), total activity volume (counts per day) between the two locations was moderately correlated (Spearman's r = 0.73). Hip and wrist monitors wear locations identically classified 71% individuals who were at the highest 40% or lowest 40% of their respective distributions. Similar patterns and slightly stronger agreements were observed when examining steps instead of VM counts.ConclusionsAccelerometer-assessed physical activity using hip- vs wrist-worn devices was moderately correlated in older, free-living women. However, further research needs to be conducted to examine comparisons of specific activities or physical activity intensity levels.