Introduction: There have been an increasing number of reports in recent years which have highlighted that the aerobic fitness test performances of Australian and New Zealand children and adolescents are declining. Some researchers have previously commented on secular changes in performance, but have used data dating back only to 1985. Using a metaanalytical approach, this study aimed to quantify the secular changes in the aerobic fitness test performances of Australasian (Australian and New Zealand) children and adolescents over the past half a century.
Methods: Forty-six studies reporting on the aerobic fitness test performances of healthy Australasian children and adolescents were included in the analysis. Corrections for methodological variation were made where possible, and data for each aerobic fitness test were expressed in a common metric. Raw data were merged with pseudo data generated from reported means and standard deviations using Monte Carlo simulation. Changes in aerobic test performance were calculated at the country x age x sex x test level using least squares linear regression.
Results: Secular changes were calculated for 161,419 6-17-year-old tested on five different maximal field-running tests of aerobic fitness between 1961 and 2002. Overall, the aerobic performance of young Australasians declined at an average rate of -0.24% per annum (95% confidence interval -0.22 to -0.26% per annum). The pattern of change, however, was not consistent over time. Early in the 1960s, changes in performance shifted from improvements to declines, with the rate of decline accelerating until about 1990, and slowing thereafter. Secular changes were reasonably similar for boys and girls, but quite different for children and adolescents.
Discussion/conclusion: There has been a marked decline in aerobic fitness test performances of Australasian children and adolescents in recent decades. It is likely that this secular decline is caused by a network of social, behavioral, physical, psychosocial and physiological factors.