Variation in physical fitness between ethnic groups in nine year olds

There is little information on cardio-respiratory fitness of children, especially in ethnic minorities in Britain. In this study we assess the associations of social factors, ethnicity, parental health related factors, child's anthropometry, blood pressure and cholesterol measurements with cardio-respiratory fitness.

Power output against load at 85% of the maximum heart rate (PWC85%), was measured, using a cycle-ergometer test, in children aged 8-9 years in 22 randomly selected areas in England, 14 in Scotland and in 20 inner city areas in England. The subjects were 317 boys and 310 girls from the English sample, 152 boys and 140 girls from the Scottish sample and 242 boys and 261 girls from the inner city sample.

Short stature (P < 0.001), fatness (P < 0.001), and Indian subcontinent origin (OR = 0.34, 95% CI: 0.16, 0.68 in boys and OR = 0.22, 95% CI: 0.12, 0.40 in girls) were associated with inability to finish the test. In those who finished the test PWC85% was greater in taller children and in those with lower skinfold values (P < 0.001, except height in boys P = 0.017). The PWC85% in those originating in the Indian continent was lower (-0.17 watt/kg, 95% CI :-0.32, -0.01 in boys and -0.29, 95% CI: -0.43, -0.14 in girls) than in white children.

Shorter and obese children have poorer physical fitness than other children. Physical fitness is lower in children originating in the Indian subcontinent than other British children. This seems to be unrelated to socioeconomic disadvantage. Physical inactivity and lack of cycling skills may explain our findings.