AND HOW FIT ARE YOU?

The Allied Dunbar National Fitness Survey

The first attempt to assess the nation’s physical fitness was published 1990 – The Allied Dunbar National Fitness Survey (ADNFS). The ADNFS was conducted in a representative sample of English adults aged 16 to 96 years, between February and November 1990. A total of 4,316 participants (76% response rate) were interviewed about a range of socio-demographic characteristics and lifestyle factors, such as diet, physical activity (type, frequency and duration), smoking, alcohol, sleep, stress and social support. A subsample of 2,767 participants also took part in a physical appraisal which included objective assessment of body dimension, composition, flexibility, and cardio-respiratory and muscular fitness.

The findings were shocking. Over 7 out of 10 men and 8 out of 10 women fell below their age-appropriate activity level for achieving a health benefit. About 1 in 6 had done no activity for 20 minutes or more in the past month. The level of inactivity fell with age, 10% of 16-20 years olds took no exercise increasing to 40% for 65-74 year olds. When tested on a treadmill the proportion of men unable to sustain uphill walking at 3mph rose from 4% in the 16-24 year olds to 81% in the 65-74 year group. For women the equivalent proportions were 34% to 92%.

The figures for muscle strength were no more encouraging, 50% of women over 55 being unable to walk upstairs without assistance. Astonishingly, 80% of both men and women of all ages incorrectly believed that they did enough exercise to keep fit – yet more evidence of the human’s capacity for self-deception.

Interestingly, though fitness tended to decline with age, many older individuals were as fit as or fitter than some of the much younger subjects.

Health Survey for England

The Health Survey for England (HSE) 2008 is the most up to date source of information on cardiovascular fitness of a wide selection of the population. Adults aged 16 to 74 were tested by using a step test – stepping up and down a single step of determined height at a fixed rate for a maximum of eight minutes. The pace of stepping increased throughout the test. Heart rate measurements were taken during and after the test, and combined with the resting heart rate to provide an estimate of the individual’s maximal oxygen uptake (VO_2max). The information in the HSE 2008 was analysed to allow comparisons to be made between the HSE 2008 and the ADNFS and this involved converting the results of the step test from the HSE to indicate the percentage of adults who could sustain walking at 3 miles per hour (mph) on the flat and on 5 per cent incline. Key findings from HSE 2008 are:

• Men had higher cardiovascular fitness levels than women, with an average level of VO_2max of 36.3 ml O₂/min/kg for men and 32.0 ml O₂/min/kg for women. In both sexes, the mean VO_2max decreased with age.
• Cardiovascular fitness was lower on average among those who were obese (32.3 ml O₂/min/kg among men and 28.1 ml O₂/min/kg among women) than among those who were neither overweight nor obese (38.8 ml O₂/min/kg and 33.9 ml O₂/min/kg respectively).
• Virtually all participants were deemed able to walk at 3 mph on the flat but 84 per cent of men and 97 per cent of women would require moderate exertion for this activity. Thirty two per cent of men and 60 per cent of women were not fit enough to sustain walking at 3 mph up a 5 per cent incline. Lack of fitness increased with age.
• Physical fitness was related to self-reported physical activity. Average VO₂max decreased, and the proportion classified as unfit increased, as self-reported physical activity level decreased. There have been a number of other studies of physical fitness in the “population” but the HSE figures are probably the most meaningful in the real world because they deliberately included as broad a cross section of society as possible. Longitudinal studies, which examine the same people over a number of years give more accurate estimates of the effects of age than cross sectional samples which examine all the subjects at one point in time.But are we really becoming more active?

  Although HSE annual surveys indicate that more of us are complying with the government’s exhortations to reach their exercise targets, there is evidence that this is not always translating into increased levels of fitness. For instance the number of British military reservists failing their fitness assessments increased from 20% in 2015 to 29% in 2018. Even the much vaunted Olympic Games stimulus to increasing sports participation is an illusion. A large survey of existing physical activity surveillance data collected before, during, and after the Olympic Games in hosting areas around the world, including the London 2012 Olympics, indicates that there was no change in the prevalence of physical activity or sports participation, except for the 2008 Summer Olympics in Beijing. Is the reported increase in exercise taking over the past decade a reflection of the notorious inaccuracy of self-reporting of physical activity? It is possible that the apparent trend for increasing activity is false and more to do with trying to satisfy the hopes and expectations of the surveyors. Is it possible that the “social desirability bias” is becoming greater as the evidence grows that exercise is so important to health?