Lankhorst K.1, van den Berg-Emons H.J.G.2, Bussmanns J.2, Horemans H.2, Stam H.2, de Groot J.1
1University of Applied Sciences, Research Group Lifestyle and Health, Institute of Human Movement Studies, Utrecht, Netherlands, 2Erasmus MC University Medical Centre, Rehabilitation Medicine, Rotterdam, Netherlands
Background: Promoting healthy physical behavior (PB), comprising both physical activity and sedentary time, is increasing to prevent health related problems later on in life in typically developing youth and peers with motor disabilities. To evaluate interventions aimed at improving PB it is important to measure this behavior objectively. Although, several device-based instruments have been validated in the adult population, none of these are validated in youth or provides feedback about the actual PB. A recently developed accelerometer (Activ8) is promising for that purpose. The Activ8 measures PB, gives real-time feedback, is easy to use and is low-priced.
Purpose: To investigate the criterion validity of the Activ8 measuring physical behavior in typically developing youth and peers with motor disabilities.
Methods: Ten typically developing children (mean age, 14 years; SD 2.5) and ten ambulatory children with motor disabilities (mean age, 12.9 years; SD 2.1) were recruited. Participants performed a series of consecutive and representative daily life activities according to a standardized protocol either at home or at school. During the test, the Activ8 and a hand-held digital camera measured the activities of the participant. For criterion validity, Activ8 output was compared with the synchronized video recordings. Primary outcome of the analyses were absolute and relative time differences between video analyses and Activ8 activity output for measuring static activities (sitting, standing) and dynamic activities (walking, cycling and running). Secondary outcome focused on the accuracy of the Activ8 in measuring each activity separately; sitting, standing, walking, cycling and running.
Results: In typically developing youth, the relative time difference between video and Activ8 for static activities was -1.3% and 0.65% for dynamic activities. Secondary analysis, looking at the different activities showed 5%, -14.7%, 0.17%, 1.78% and 0.94% difference for resp. sitting, standing, walking, cycling and running. In youth with motor disabilities, the relative time difference for static activities was 0.72% and -0.38% for dynamic activities. The percent difference of time in duration of each measured activity was 6.92%, -11.63%, -19.15%, 30,94%, 16.74% for sitting, standing, walking, cycling and running, respectively in youth with motor disabilities.
Conclusion(s): This study demonstrated excellent validity of the Activ8 in distinguishing static from dynamic activities in daily life in both typically developing youth and those with motor disabilities. Looking at specific activities in typically developing youth, the Activ8 demonstrated as well an excellent validity. In youth with motor disabilities, the Activ8 demonstrated a validity ranged from good-excellent for measuring specific activities. The Activ8 overestimated cycling and running, while walking and standing were underestimated in youth with motor disabilities.
Implications: Device-based measurement tools, like the Activ8, can measure an important component of PB, which consists of both static and dynamic activities. The Activ8 provides the researcher, physical therapist, parent and child real-life PB information. In that perspective, using the Activ8 provides new possibilities to assess associations with health, to monitor change of PB over time and to estimate population prevalence of meeting physical activity guidelines in a valid way. Future research will involve studying the effect of giving feedback for optimizing PB using this device.
Funding acknowledgements: Unconditional grant (PRO-4-03) of the Dutch Foundation Innovation Alliance (SIA-RAAK), part of the Dutch Organization for Scientific Research (NWO)
Topic: Paediatrics
Ethics approval: Approved by the Medical Ethical Committee of the Erasmus University Medical Center Rotterdam, the Netherlands (MEC number: MEC-2013-404)
All authors, affiliations and abstracts have been published as submitted.
