The potential for fitness tests to be misleading can be illustrated by considering aerobic fitness - the fitness component most often associated with health. Maximal oxygen uptake (the highest rate at which a person can consume oxygen during exercise) is the best laboratory measure of aerobic exercise, but in schools the 20-metre shuttle run or "bleep test" is the most popular test of aerobic fitness.
Despite the popular view that children are less aerobically fit than in previous generations, there is no evidence to support a fall in maximal oxygen uptake since the first laboratory measures of children in the 1930s.
Bleep test scores, however, suggest a decline in children's aerobic fitness over the past 20 years. But this has coincided with a dramatic increase in the number of overweight young people and as bleep tests require body mass to be moved, it's more likely that scores reflect a general increase in body mass than a decrease in aerobic fitness.
Overweight young people are heavily penalised in bleep tests as moving their body involves them doing more work during each shuttle run.
This means they are likely to stop earlier than their leaner peers and have their aerobic fitness underestimated. Exposing the limitations of these children in this way is unlikely to help them become more active. If the scores are used for subsequent exercise prescriptions then the programme developed will focus on the wrong issues, such as improving fitness instead of increasing energy use.
Fitness tests are often used to classify students and I'm frequently contacted by teachers requesting norm tables for aspects of children's fitness, but do they serve any purpose? Using them confounds the issue of relative fitness, as tables based on age can't be used to interpret the level of fitness of young people at different stages of maturity.
Constantly comparing children on the basis of test scores is likely to negatively affect those who score low. Having different norms for boys and girls also results in different expectations. Norms are based on performances rather than capabilities and if teachers accept lower norms for girls as reflecting acceptable performances, girls will tend to meet these lower expectations.
Fitness tests at best only distinguish the mature andor motivated from the immature andor unmotivated. They can't be used to compare fitness.
Students generally view fitness testing unfavourably and as a major reason for their negative attitudes towards physical education. There is little, if any relationship between fitness test scores and habitual physical activity. The major problem facing physical educators is the sedentary lifestyles of many of their students. Would the time devoted to fitness testing not be better spent promoting physical activity?
Professor Neil Armstrong is the director of the Children's Health and Exercise Research Centre, Exeter University.