Objective: Accelerometer-determined physical activity, sedentary behavior and energy expenditure estimation may be influenced by the accuracy of accelerometer-assessed inclinometer. The purpose of this study was to examine the accuracy of the ActiGraph GT9X (most recent ActiGraph model) inclinometer across participant body habitus, and in particular, differences in central adiposity.
Methods: Eighteen participants (Mage = 21.5 years) completed a series of 11 consecutive activities that varied in both movement (i.e., no movement, walking and pedaling) and anatomic position (i.e., lying, sitting and standing). During the trials, participants wore an ActiGraph GT9X accelerometer, with direct observation used to compare body position determination derived from the ActiGraph GT9X inclinometer.
Results: The ActiGraph GT9X inclinometer demonstrated moderate accuracy (>68%) in body position determination for sedentary behaviors, high accuracy (>95%) in body position determination for ambulatory-based activities (e.g., walking and jogging), and had varied accuracy (100% vs. 32.1%) in identifying non-wear.
Conclusion: The exclusive use of inclinometry for sedentary behavior and non-wear determination is not recommended.
Key words: Accelerometry; body posture; energy expenditure
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