Validation of Accelerometer Thresholds and Inclinometry for Measurement of Sedentary Behavior in Young Adult University Students

Abstract

Sedentary behavior (SB) is a major contributor to obesity and significant morbidity and mortality in adolescence and adulthood, yet measurement of SB is still evolving. The purpose of this study was to assess the degree of construct validity of the inclinometer function and single-axis and vector magnitude accelerometry metrics of the ActiGraph GT3X+ in objectively measuring SB and physical activity in 28 young adult university students who performed nine semi-structured activities, each for five minutes: lying, sitting, reading, seated video gaming, video watching, seated conversation, standing, stationary biking, and treadmill walking. Inclinometry and four output metrics from the ActiGraph were analyzed in comparison to direct observation by a researcher recorded each minute. For overall accuracy in measuring both SB and physical activity, all four accelerometer metrics (94.7-97.8%) outperformed the inclinometer function (70.9%). Vector magnitude accelerometry with a threshold of 150 counts per minute as the cut point for sedentary behavior was superior to other methods. While accelerometry was more accurate overall at detecting the behaviors tested, inclinometry had some advantages over accelerometry methods at detecting walking, biking, and standing. The findings support use of accelerometry as a valid objective measure of body movement, while use of inclinometry as a sole measure is not recommended. Additional research would be beneficial to improve the calibration of the inclinometer and explore ways of combining this with accelerometer data for objectively measuring SB and physical activity.

Accuracy of the ActiGraph GT9X Inclinometer to Assess Human Body Postures

“…Our findings demonstrated that the ActiGraph GT9X accelerometer correctly classified sedentary behaviors 68.8% (trial 1), 83.5% (trial 2), 69.5% (trial 3), and 74.1% (trial 4) of the time, with the average of these four trials being 74%. This average (74%) is similar (70.9%) to a recent study evaluating the accuracy of the ActiGraph GT3X inclinometer across a variety of sedentary behaviors among young adults [14]. Carr and Mahar [5] also reported that 71.8% of light-intensity walking was correctly identified as standing, with our estimates averaging 98% (96% for trial 6, 100% for trial 7).…”

Sedentary behavior and physical activity of young adult university students

“…Well‐established standardized cutoffs determine the level of intensity of body movement. For example, body movement of less than 150 counts per minute is sedentary, whereas 6,000 counts or more per minute is vigorous physical activity (Peterson, Sirard, Kulbok, DeBoer, & Erickson, ; Troiano et al, ). For this study, a low‐frequency extension setting was used to ensure that the accelerometer would capture even the slightest sedentary‐level movements without inadvertently classifying that time as the device being off.…”

“…Missing data have been noted to range from 0–3% (de Vries et al, ). GT3X+ accuracy ranges between 80% and 100% for SB in laboratory conditions (Carr & Mahar, ; Peterson et al, ; Sasaki, John, & Freedson, ) and in free‐living conditions (Kaminsky & Ozemek, ; Santos‐Lozano et al, ). The device construct validity is high ( r = .39 to .90; de Vries et al, ) with agreement between accelerometer‐derived SB and direct observation between 80% and 98% (Carr & Mahar, ; Hänggi et al, ).…”

Physical activity and myopia in Danish children—The CHAMPS Eye Study

“…) and adolescents (Peterson et al. ). Counts per minute (CPM) was used as an estimate of overall mean intensity of PA, and cut‐off points were defined for four PA intensity levels (sedentary (SED), light (L), moderate (M) and vigorous (V)) according to previous studies (Trost et al.…”