Site-specific Concurrent Validity of the ActiGraph GT9X Link in the Estimation of Activity-related Skeletal Loading

Abstract

To inform the development of bone-specific physical activity (PA) assessment methods and contribute to bone-specific PA guidelines, accelerometer outcomes that provide the most valid estimates of skeletal loading in adults must be identified. Purpose: The aims of this project were twofold: 1) to assess the concurrent validity of raw accelerometer outputs with ground reaction forces (GRF) and loading rates (LR) calculated from force plate across a range of simulated habitual PA and 2) to identify the optimal wear site among the ankle, hip, and wrist with the strongest relationships between accelerometer and force plate and/or skeletal outcomes. Methods: Thirty healthy young adults (23.0 ± 4.5 yr, 50% female) wore a triaxial accelerometer at the right ankle, hip, and wrist while performing eight trials of walking, jogging, running, low box drops, and high box drops over an in-ground force plate. Repeated-measures correlations and linear mixed models were used to assess concurrent validity of accelerometer and force plate outcomes across wear sites. Results: Strong repeated-measures associations were observed between peak hip resultant acceleration and resultant LR (r rm 1169 = 0.74, P < 0.001, 95% confidence interval = 0.718, 0.769) and peak hip resultant accelerations and resultant GRF (r rm 1169 = 0.69, P < 0.001, 95% confidence interval = 0.660, 0.720) when data were combined across activities. By contrast, small to moderate associations were seen between ankle-based outcomes and corresponding GRF and LR during walking and jogging (r rm 209 = 0.17-0.34, all P < 0.001). No significant associations were seen with wrist-based outcomes during any activity. In addition, linear mixed models suggested that 24%-50% of the variability in peak GRF and LR could be attributed to measured accelerations at the hip. Conclusion: Peak accelerations measured at the hip were identified as the strongest proxies for skeletal loading assessed via force plate.

Validity of New Technologies That Measure Bone-Related Dietary and Physical Activity Risk Factors in Adolescents and Young Adults: A Scoping Review

“…Table 1 shows the study characteristics. One study was conducted in Canada [ 27 ], one from Australia [ 28 ], one from the UK [ 29 ] and one from the USA [ 30 ]. The earliest publication date was 2012 and the most recent was 2020.…”

“…The earliest publication date was 2012 and the most recent was 2020. Two studies assessed physical activity [ 29 , 30 ] and two assessed diet [ 27 , 28 ]. Of the dietary studies, one study examined calcium [ 28 ], while the other examined calcium and vitamin D [ 27 ].…”

“…The sample size ranged from 10 to 50 participants, with n = 130 individuals included in this review, 65% of the total being female. One study consisted of only female participants [ 28 ], while the others comprised of individuals of both genders equally [ 27 , 29 , 30 ].…”

“…One study used three tri-axial accelerometers (GT1M, GT3X+ and GENEA) [ 29 ], while the other study used one tri-axial accelerometer, the GT9X Link [ 30 ]. The positioning of the accelerometers varied from the right hip [ 29 , 30 ], right wrist [ 29 , 30 ] and left wrist [ 29 ] to the right ankle [ 30 ]. All studies used the sampling rate of 100 Hz for the ActiGraph devices (GT3X+ and GT9X Link), while 80 Hz was used for the GENEA.…”

“…The GT1M was set to collect data in counts (vertical axis, 1 s epoch). The operating range varied between studies, from 6 [ 29 ] to 8 g [ 30 ]. The force plate, used to collect GRF, ranged from 960 [ 29 ] to 1000 Hz [ 30 ].…”