Purpose. This study aimed to (i) explore children’s compliance to wearing wrist and hip-28 mounted accelerometers, (ii) compare children’s physical activity (PA) derived from wrist 29 and hip raw accelerations, and (iii) examine differences in raw and counts PA measured by 30 hip-worn accelerometry. 31 Methods. One hundred and twenty nine 9-10 y old children wore a wrist-mounted 32 GENEActiv accelerometer (GAwrist) and a hip-mounted ActiGraph GT3X+ accelerometer 33 (AGhip) for 7 d. Both devices measured raw accelerations and the AGhip also provided 34 counts-based data. 35 Results. More children wore the GAwrist than the AGhip regardless of wear time criteria 36 applied (p<.001 - .035). Raw data signal vector magnitude (SVM; r = .68), moderate PA 37 (MPA; r = .81), vigorous PA (VPA; r = .85), and moderate-to-vigorous PA (MVPA; r = .83) 38 were strongly associated between devices (p<.001). GAwrist SVM (p = .001), MPA (p = 39 .037), VPA (p = .002), and MVPA (p = .016) were significantly greater than AGhip. 40 According to GAwrist raw data, 86.9% of children engaged in at least 60 min MVPA∙d-1, 41 compared to 19% for AGhip. ActiGraph MPA (raw) was 42.00 ± 1.61 min∙d-1 compared to 42 35.05 ± 0.99 min∙d-1 (counts) (p=.02). Actigraph VPA was 7.59 ± 0.46 min∙d-1 (raw) and 43 37.06 ± 1.85 min∙d-1 (counts; p=.19). 44 Conclusion. In children accelerometer wrist placement promotes superior compliance than 45 the hip. Raw accelerations were significantly higher for GAwrist compared to AGhip, 46 possibly due to placement location and technical differences between devices. AGhip PA 47 calculated from raw accelerations and counts differed substantially, demonstrating that PA 48 outcomes derived from cutpoints for raw output and counts cannot be directly compared.
Fairclough, S., Noonan, R., Rowlands, A., van Hees, V., Knowles, Z., & Boddy, L. (2016). Wear compliance and activity in children wearing wrist and hip mounted accelerometers. Medicine & Science in Sports & Exercise, 48(2), 245-253. https://doi.org/10.1249/MSS.0000000000000771