Six-year changes in body mass index and cardiorespiratory fitness of English schoolchildren from an affluent area

We compared values of body mass index (BMI) and cardiorespiratory fitness (20 m shuttle-run test) of n =157 boys and n =150 girls aged 10–11 measured in 2014 with measures from 2008 and 1998. Boys’ fitness was lower ( d =0.68) in 2014 than 2008, despite a small ( d =0.37) decline in BMI. Girl’s BMI changed trivially ( d =0.08) but cardiorespiratory fitness was lower ( d =0.47) in 2014 than 2008. This study suggests fitness is declining at 0.95% per year, which exceeds the 0.8% rate of decline we reported between 1998 and 2008 and is double the global average of 0.43%. Declines in fitness were independent of changes in BMI suggesting continued reductions in English children’s habitual physical activity levels.