Despite the positive points of self-report methods, studies have documented that children aged 10 years and younger are unable to recall their previous activities accurately 6,7 because the activity bouts are often very short and spontaneous, making recall difficult 8. Available evidence indicates that self-report measures have many advantages such as the ability to record physical activity type and context in a historical way, at low cost and with ease of administration 5. Self-report measures vary considerably with respect to the quantity and quality of information they can provide for the type, frequency, duration and intensity of the activity.
When surveying children, this method includes self-administered recalls, interviewer administered recalls, direct and proxy reports completed by either parents or teachers. Self-reporting is one of the most common subjective methods used in epidemiological and surveillance studies. These include the ratio of the activity energy expenditure to the resting energy cost, oxygen consumption per unit of body mass per unit of time (mL/kg/min), multiples of resting metabolism or ‘metabolic equivalents’ (METs) 4, duration of activity bout spent at sedentary, light, moderate and vigorous intensity levels and the total time spent in bouts of moderate-to-vigorous physical activity (MVPA) combined 3. Several classification units are used in measuring physical activity behaviours. Thus, measuring physical activity behaviours in children and adolescents is extremely difficult, making it is necessary to have valid and reliable tools that are capable of including all of the relevant dimensions and domains 3.
Further, physical activity behaviours can be characterised according to the dimensions of type, intensity, frequency and duration. Usually, physical activity domains include all types of activities performed during free-time or leisure-time, transportation activities, all tasks performed in the home environment, physical education sessions and break-time at school. Free-living physical activity behaviours in children and adolescents are considered one of the most complex domains to assess.
The term ‘physical activity’ has been described as referring to any bodily movement produced by the skeletal system and muscles that results in energy expenditure 1,2.
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