Physical activity prevalence in australian children and adolescents: why do different surveys provide so different estimates, and what can we do about it?

To illustrate how the differences in measurement protocols affect physical activity (PA) monitoring among Australian children and adolescents aged ~5-17 years, this review aimed to summarize and critically assess the most recent findings from the national and state or territory health surveillance systems and population surveys. We compared methods and results of 21 population surveys identified in an extensive web-based search conducted using the entries ‘Physical Activity’, ‘Surveillance’, ‘Monitoring’, ‘Survey’, ‘Australia’ and the names of Australian states and territories as keywords. A large variability between PA prevalence rates from different Australian national- and state-level surveys was observed, both for selfreported and pedometer-based estimates. The prevalence estimates tended to be: [i] higher among children when compared with adolescents; [ii] higher for boys than for girls when assessed using self-reports; and [iii] higher for girls than for boys when assessed using pedometers. The true prevalence of compliance with PA guidelines among children and adolescents in Australia seems to be difficult to determine. To ensure comparability of prevalence estimates, key elements of data collection and processing protocols, such as PA questionnaires, survey administration modes, survey time frames, and definitions of a ‘sufficient’ PA level, should be standardised throughout all PA surveillance systems and population surveys in Australia.