ABSTRACT
Although many physical activity measures exist, the majority prove unsuitable for examining habitual physical activity within a child population; this has led to an increase in the use of movement sensors, such as accelerometers, to undertake such tasks (Puyau et al., 2004). The advantages of this method include minimal burden to the user (Rowlands et al., 2004), while their small size allows for easy use with children (Freedson et al., 2005). Several accelerometers, e.g. the Actical (Mini Mitter, Bend, Oregon, USA), the ActiGraph GT1M (ActiGraph, Pensacola, Florida, USA) and the RT3 (Stayhealthy Inc., Monrovia, California, USA), have been validated for use with both adults and children. However, lack of compliance with the wearing protocol when using these accelerometers can lead to a reduction in participant numbers. For example, Van Coevering et al. (2005) found that only 50 % of students were compliant for the full 7 day measurement period where as 92 % of students were compliant for ≥ 3 days. The issue of non compliance may be exacerbated by the necessity to remove the monitor when changing clothes (as most are worn on the hip) and when partaking in water-based activities (due to the lack of waterproofing). In an attempt to overcome these problems, the GENEA waveform triaxial accelerometer was developed (Unilever Discover, Colworth, UK, manufactured and distributed by Activinsights Ltd, Kimbolton, Cambridge, UK).
