Temporal changes in long-distance running performance of Asian children between 1964 and 2009.

Aerobic fitness is considered to be an important marker of current health and even a predictor of future health. The aim of this study was to systematically analyse the available scientific information on temporal changes in maximal long-distance running performance (a widely and long-used marker of aerobic fitness) of Asian children. A systematic review of the scientific literature was undertaken to locate studies explicitly reporting on temporal changes (spanning a minimum of 5 years) in maximal long-distance running of apparently healthy (free from known disease or injury) Asian children aged 9-17 years. Studies were located up to October 2010 via computerized searching of bibliographical databases, reference list searching and personal communication with international experts. Temporal changes were analysed at the country by sex by age by test level using best-fitting linear or polynomial regression models relating the year of testing to long-distance running performances expressed as average running speeds. Changes in means were expressed as percent changes and as standardized effect sizes. Eight studies reporting temporal changes in the long-distance running performance of 23,897,571 children aged 9-17 years from four Asian countries over the period 1964-2009 were included. Overall, there was a large decline in long-distance running performance equivalent to -16.6 ± 1.3% (mean change ± 95% confidence interval) or -1.2 ± 0.1 standard deviations. Temporal changes were generally consistent for different sex and age groups, but not for different countries, with large declines observed for children from China and the Republic of Korea, small declines for children from Japan and very small declines for children from Singapore. There is overwhelming evidence of meaningful declines in the maximal long-distance running performance of Asian children in recent decades, which are probably caused by a network of social, behavioural, physical, psychosocial and physiological factors. These declines highlight the need for regular surveillance of Asian children's health-related fitness and proactive public health strategies.