Longitudinal patterns in objective physical activity and sedentary time in a multi-ethnic sample of children from the UK

BACKGROUND Children of south Asian decent born in the UK display lower levels of physical activity than British Caucasians although no longitudinal data are available. OBJECTIVES We aimed to investigate change in activity levels over 1-year in a diverse ethnic sample of children residing in London, UK. METHODS Children were categorised into ethnic groups (Caucasian/mixed, black, south Asian). At baseline and 1-year follow-up children’s objective physical activity was monitored (Actigraph accelerometer) for at least one day. Mixed models were employed to investigate differences in change in activity levels between ethnic groups. RESULTS A total of 281 children were included in the analyses. South Asians had a significantly greater increase in time spent sedentary at follow-up than those of a Caucasian/mixed ethnicity (B [ratio sedentary/wear time] = 0.024; 95% CI 0.003, 0.046). South Asian children recorded lower moderate to vigorous physical activity at baseline (B= -6.5, 95% CI, -11.1, -1.9 min/d, p=0.006) although levels remained relatively stable over follow-up and changes did not differ across ethnic group. CONCLUSIONS In a diverse ethnic sample of children from inner city London, those of a south Asian ethnicity exhibited a significantly greater increase in sedentary time over a period of 12 months in comparison to Caucasian/ mixed and black children.