Calibration of the RT3 accelerometer for various patterns of physical activity in children and adolescents

Abstract

The aim of this study was to determine thresholds for various intensities of physical activity in children and adolescents using the RT3 accelerometer. Forty healthy participants aged 10-16 years were recruited to the study. To validate the RT3 accelerometer data, an independent sample of 20 children and adolescents aged 10-16 years performed the same activities. Accelerometer data, heart rate, and oxygen consumption were measured at nine levels of physical activity, which varied in intensity: sedentary, light, moderate, and vigorous. Age and sex did not affect thresholds. The activity categories and accelerometer counts were: sedentary activity, 0-40 counts x min(-1); light activity, 41-950 counts x min(-1); moderate activity, 951-3410 counts x min(-1); and vigorous activity, >3410 counts x min(-1), respectively. These thresholds were considered valid as the difference between threshold values obtained using two independent groups of children was not significant. This study has established threshold values for various physical activities and enables the RT3 accelerometer to be used to quantify the duration of various levels of activity in adolescents under free-living conditions.

How many days of accelerometer monitoring predict weekly physical activity behaviour in obese youth?

“…The RT3 is 71 9 56 9 28 mm, and weighs 62Á5 g and can store data recorded at 1-min epoch for up 21 days (Vanhelst et al, 2010). The RT3 measures acceleration in three dimensions according to a vertical vector (x), an anteroposterior vector (y) and a mediolateral vector (z).…”

“…The epoch interval was set at one min, and output was expressed as mean counts per minute in VM. Physical activity was divided into the following classifications: sedentary activity, 0-40 counts min À1 ; light activity, 41-950 counts min À1 ; moderate activity, 951-3410 counts min À1 ; and vigorous activity, >3410 counts min À1 (Vanhelst et al, 2010). …”

Use of pedometers and accelerometers in clinical populations: validity and reliability issues

“…However, some researchers have begun developing their own cut-points for the RT3 in child and adolescent populations. 45 The limited validity studies performed to date indicate that the RT3 performs in a manner similar to the ActiGraph and Actical. In a validation study using structured activity bouts, the RT3 overestimated activity EE for all activities combined, overestimated TM activities by 9%, and underestimated activities of daily living by 34%, compared to indirect calorimetry.…”

“…46 In terms of reliability, the RT3 has been found to have good reliability within RT3 units, but poor reliability among RT3 units. 45,47 SenseWear Pro Armband…”

Comparison of Patterns of Physical Activity and Sedentary Behavior Between Children With Cerebral Palsy and Children With Typical Development

“…RT3 accelerometer cut-points developed by Vanhelst et al 34 were used to classify sedentary behavior and physical activity intensity as, when compared to other published RT3 accelerometer cut-points, they provide the most accurate estimate of physical activity intensity in children with and without CP. 35,36 An overview of the physical activity variables that were calculated is provided in Table I.…”