Accuracy of Actigraph inclinometer to classify free-living postures and motion in adults with overweight and obesity

ABSTRACT

Sedentary behaviour (SB) is an independent health risk-factor and interrupting SB seems to be beneficial. SB is both defined by posture and intensity, thus objective measurement of postures remains a priority. The ActivPAL inclinometer (AP) has been used as a reference for postural estimation, but information on the validity of the Actigraph inclinometer (AG_incl) is scarce. We compared postural estimation from waist-worn AG_incl against thigh-worn AP, under free-living. Data from 10 participants (50.4 ± 11.4 years) were used and each 15s-block from 60-valid days was matched for the devices’ comparison. At group level, no differences were found for SB and standing-time between inclinometers (p ≥ 0.05). AG_incl underestimated stepping-time by 26.3 min and overestimated SB-to-upright transitions by 200.7 occasions (p < 0.05). Inter-individual variability was higher for SB and standing-time, and AG_incl was in better agreement with AP for the stepping-time (area under the ROC curve = 0.98, with 100% sensitivity and 94% specificity; CCC = 0.44). These results highlight potential error in estimating individual postures using AG_incl in overweight/obese adults and provide insights on the differences of using specific criteria on data-analysis. Our findings suggest that at the group level, AG_incl provides similar estimates compared to AP for SB and standing-time, but not for SB-to-upright transitions or stepping-time. (ClinicalTrials.govID:NCT02007681)

KEYWORDS:

• Sedentary behaviour
• standing time
• transitions
• objective methods
• ActivPAL (AP)

Acknowledgments

PBJ is supported by the Portuguese Foundation for Science and Technology with a post-doctoral scholarship (SFRH/BPD/115977/2016). The funding sources had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; or preparation, review, or approval of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

PBJ is supported by the National funding from the Portuguese Foundation for Science and Technology [SFRH/BPD/115977/2016] .