Researchers at the University of Cambridge said the patterns mirror inequalities seen in levels of childhood obesity – which has increased tenfold on a global level over the past four decades – and suggests the need for greater focus on the promotion of exercise.
Children from specific ethnic minority backgrounds, including Pakistani and Bangladeshi, have lower levels of vigorous physical activity, according to the researchers.
There are also widening inequalities in obesity prevalence.
By the age of 11, UK children from disadvantaged families are three times as likely to be obese than more advantaged children.
There are also stark ethnic and racial differences in levels of childhood obesity, with higher rates of obesity within certain ethnic minorities including children from Black African, Black Caribbean, Pakistani and Bangladeshi backgrounds.
Evidence suggests that more vigorous intensity activity – such as running or swimming – is more strongly linked with reduced waist circumference and body fat than moderate intensity activity. International guidelines say that children should engage in moderate-to-vigorous intensity activity for at least 60 minutes per day.
Rebecca Love, a Gates Cambridge Scholar at the Centre for Diet and Activity Research at Cambridge, said: “When we look at overall physical activity we don’t see clear differences between children from different backgrounds despite clear inequalities in obesity. To investigate further, we looked at whether overall physical activity was hiding inequalities in the intensity with which that activity is performed that might explain these patterns.”
The researchers studied data from almost 5,200 children aged seven years who were part of the Millennium Cohort Study, of children born in the UK between September 2000 and January 2002.
The children were given accelerometers and their activity measured for a minimum of ten hours for three days. The results are published today in the journal BMJ Open.
The team found the higher the level of education attained by the mother, the more minutes of vigorous intensity activity her child was likely to have, accounting for time spent in moderate physical activity. Children with mothers with high levels of education accumulated three minutes more vigorous activity per day then those with low levels of education. Similarly, the team found significantly more time spent in vigorous intensity activity incrementally with increasing household income.
Intensity differences were also apparent by ethnicity. White British children perform on average more than three minutes more daily vigorous physical activity in comparison to children from Pakistani and Bangladeshi backgrounds. Children from “other ethnic groups” also accumulated 2.2 minutes fewer daily vigorous intensity activity overall.