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Using Ecological Momentary Assessment to estimate raw accelerometer thresholds
Background: Raw accelerometer thresholds were based on absolute intensity and developed in lab-based environments.Purpose: To use Ecological Momentary Assessment (EMA) to estimate raw accelerometer thresholds using ‘naturally occurring’ activities in different domains, based on measures of perceived exertion in mid-age adults in Brisbane.Methods: Participants (N= 50, 40-65 years) wore an ActiGraph tri-axial accelerometer (GT9x Link) on the non-dominant wrist and responded to six EMA questionnaires per day for seven days. EMA questions were used to collect information about type and duration of each activity, as well as rate of perceived exertion (0-10) of the activity conducted prior to the prompt. Linear mixed models were used to estimate perceived exertion values and acceleration outputs (mg) and to estimate ranges of acceleration for three categories of perceived exertion [less than moderate (0-2); less than severe (3-5); severe or more (6-10)]Results: Median acceleration for categories of intensity based on perceived exertion were 36.0 mg for “less than moderate”, 74.5 mg for “less than severe” and 87.5 mg for “severe or more”. The proposed intensity thresholds for intensity based on perceived exertion were 89 mg for “less than severe” and 385 mg for “severe or more”.Conclusions: The widely adopted raw accelerometer thresholds may be too high to detect vigorous activity in a real-world setting. Thresholds estimated in this study, based on perceived exertion can be used in future studies as they have ecological validity.Funding: Ruth Brady is supported by a University of Queensland and University of Exeter (QUEX) Institute Studentship. Gregore Mielke is supported by a National Health and Medical Research Council Investigator Grant.Keywords: raw accelerometer thresholds, Moderate physical activity, vigorous physical activity,
Submitting Author
Ruth Brady
Population Group
Adults
Study Type
Measurement or surveillance
Setting
Not Applicable