Moving beyond BMI for assessing the health of young people in Kingston-upon-Hull
Much has been written in recent years about the childhood obesity epidemic which is affecting record numbers of children from around the UK. However, what is perhaps less well known is that levels of muscular fitness and habitual physical activity have also declined significantly in young people over the past 25 years.
This is a considerable problem given the strong association between low levels of physical activity and muscular fitness, and the increased risk of cardiovascular disease and musculoskeletal ill-health. A team in the Department of Sport, Health & Exercise Science at the University of Hull led by Professor Lee Ingle has recently investigated this issue in two secondary schools in the Kingston-upon-Hull region. The study, recently published in the European Journal of Sports Science, compared the performance of nearly 600 boys and girls from the Hull region with an age- and sex-matched group of school children from similar socio-economic backgrounds in the south-eastern region of England. Each child completed a physical activity recall questionnaire, a vertical jump test, and a hand-grip strength test. Boys from the south-eastern region had significantly stronger hand-grip scores, jumped higher, were more powerful, and reported being more physically active than their male counterparts in the Hull region. In girls, the opposite trend was evident. Girls from the Hull region were stronger (based on hand-grip strength), jumped higher, and were more powerful than their peers from the south-eastern region. All analyses were adjusted to account for differences in age, body mass index (BMI), physical activity levels, and area level deprivation, between the children in the two regions.
Declines in young people’s fitness have prompted calls for the introduction of a more systematic surveillance of fitness in the UK, possibly as an addition to the current measurement of BMI (body mass divided by the square of body stature) within the National Child Measurement Programme (NCMP). There has been resistance to these calls from some quarters with concerns focused on how such a testing regime would impact on children of lower abilities. Parents of children deemed overweight or obese according to NCMP data receive a letter warning of potential ill-effects to their child’s health. Interpreting a single measure of body size for identifying an increase in health risk is clearly problematic. In our study, based on BMI alone, one interpretation of the data could be that boys from the south-eastern region and girls from the Hull region have greater health risks due to higher adiposity indicated by their higher BMIs (based on mean scores). However, when BMI values are interpreted in conjunction with measures of muscular fitness (from the hand-grip strength test), the data suggests no increased health risks as boys from the south-eastern region and girls from the Hull region are also stronger. The higher BMI values are likely to indicate greater lean body mass in these groups, not excessive adiposity. Therefore, we advocate the implementation of a functional test such as the hand-grip strength test (which is less likely to impact on children of lower abilities) beyond a single assessment based on BMI within the NCMP. Furthermore, the identification of significant regional variations in muscular fitness that was not explained by anthropometric differences suggests that our current normative data derived from large regional samples (>10 000 children) should be expanded and updated. Therefore, a more systematic approach to fitness testing incorporating as many schools as possible in the Hull region is required prior to roll-out of any national fitness surveillance programme.
More information about the study can be found at the link below:
Lee Ingle, Ashlie Stephenson & Gavin R. Sandercock (2016): Physical activity profiles and selected muscular fitness variables in English schoolchildren: A north–south divide? European Journal of Sport Science. DOI: 10.1080/17461391.2016.1183714