Validity and reliability of the activPAL3 for measuring posture and stepping in adults and young people

Abstract

Characterisation of free-living physical activity requires the use of validated and reliable monitors. This study reports an evaluation of the validity and reliability of the activPAL3 monitor for the detection of posture and stepping in both adults and young people. Twenty adults (median 27.6y; IQR22.6y) and 8 young people (12.0y; IQR4.1y) performed standardised activities and activities of daily living (ADL) incorporating sedentary, upright and stepping activity. Agreement, specificity and positive predictive value were calculated between activPAL3 outcomes and the gold-standard of video observation. Inter-device reliability was calculated between 4 monitors. Sedentary and upright times for standardised activities were within ±5% of video observation as was step count (excluding jogging) for both adults and young people. Jogging step detection accuracy reduced with increasing cadence >150stepsmin(-1). For ADLs, sensitivity to stepping was very low for adults (40.4%) but higher for young people (76.1%). Inter-device reliability was either good (ICC(1,1)>0.75) or excellent (ICC(1,1)>0.90) for all outcomes. An excellent level of detection of standardised postures was demonstrated by the activPAL3. Postures such as seat-perching, kneeling and crouching were misclassified when compared to video observation. The activPAL3 appeared to accurately detect 'purposeful' stepping during ADL, but detection of smaller stepping movements was poor. Small variations in outcomes between monitors indicated that differences in monitor placement or hardware may affect outcomes. In general, the detection of posture and purposeful stepping with the activPAL3 was excellent indicating that it is a suitable monitor for characterising free-living posture and purposeful stepping activity in healthy adults and young people.

Agreement between activPAL3c accelerometers placed at different thigh positions

“…This is important given the increasing importance of the pattern of seated or sedentary behaviour in relation to chronic disease risk [35] and mortality. [4] Our findings also support the recent findings of Sellers and colleagues [15] which show that although monitors placed in different location result in differing outcomes, there is high level of agreement between attachment site for a range of activities.…”

“…This would be interpreted as a 'high' correlation. 25 Our findings are similar to those of Sellers and colleagues [15] who noted a difference in activity classification from activPAL3 monitors placed in differing locations on the anterior right and left thigh and attributed this to differences in monitor orientation resulting from the curvature of the anterior thigh. This may be an issue for studies examining day to day variability in behaviour.…”

“…[13], with moderate to very high test-retest reliability across a range of activities [14]. Similarly, the activPAL3 accelerometer has demonstrated validity for the assessment of step count and posture [15].…”

“…Their study reported ICC (2,1) values between 0.79 (walking) to >0.99 (time in standing and sitting/lying positions and postural transitions) which led the authors to conclude that attachment sites may be used interchangeably. Recently, Sellers and colleagues [15] reported good to excellent interdevice reliability for activPAL3 monitors across a range of tasks, and accurately detected standard postures such as sitting and…”

Physical performance following acute high-risk abdominal surgery: a prospective cohort study

“…It also includes an inclinometer that can register the number of transitions made from sitting to standing and from standing to sitting. 34,35 The validity of the activPAL has been confirmed in both healthy and hospitalized elderly people. 36,37 The monitor was attached to the skin on the anterior of the mid thigh.…”