Physical fitness is a requirement for a number of Uniformed Services including Police, Firefighters and Prison Officers. All three have implemented fitness standards and fitness testing in the past few years. Some of the background to this is outlined below.
Aerobic fitness is generally expressed as VO2Max, a measure of the maximum volume of oxygen that can be taken up by the body in one minute. This is usually expressed as millilitres per kilogram per minute to correct for individual variation in size. This represents quite a complex expression, and a much simplified approach is to simply consider the amount of energy consumed at rest for any individual and equate this to a ‘Metabolic Equivalent of Task’ (MET) of 1. Any activity will be a multiple of this, so for anyone whether they are 5’2 and 7st or 6’6” and 18st, at rest their MET will be 1 and when walking briskly their MET will be roughly 3.5. There is a direct read across from VO2Max to MET by multiplying the MET value by 3.5. Hence a VO2Max or 35 is 10 METs.
Personnel with low cardiorespiratory fitness will be at risk of illness and injury when undertaking physically demanding tasks. The key physical task for police and prison officers is control and restraint, where the sudden physical activity is combined with uncertainty and threat, with a surge of adrenaline. There are a number of demanding tasks that firefighters can undertake. This can put particular strain on the heart. There is evidence from firefighters that the risk of a sudden cardiovascular event increases below a VO2Max of 42 and becomes substantial below a VO2Max of 35 (Baur et al., 2012, Kales et al., 2003, Lee et al., 2011). A large national cohort of Swedish military conscripts found a clear increased risk of ischaemic heart disease among those who had low aerobic fitness and those who had high body mass index (BMI); fitness and BMI were independent risk factors (Crump et al., 2016). There is no evidence of any difference in risk between men and women at specific levels of aerobic fitness.
There is a clear requirement under the Health and Safety at Work Act 1974 (HSWA), clarified in the Management of Health and Safety at Work Regulations 1999 to assess risk and provide a safe working environment. The duties under the HSWA apply to both employers and employees. This implies a duty on both to ensure they are physically fit enough to be safe undertaking their role. Evidence indicates that the risk increases substantially below a VO2Max of 35. In the absence of any evidence showing a difference, this level should be considered the same for both men and women.
A validated multi-stage shuttle run test (MSSRT) was first developed in 1982 (Leger and Lambert, 1982) and validated against VO2Max in 1987 (Ramsbottom et al., 1988). The MSSRT was a 20m shuttle run, and was considered unsuitable for many organisations with smaller locations. Loughborough University developed a modified version, the 15m multi-stage fitness test (MSFT), in 1995 for the Metropolitan Police and this was validated against VO2Max by Roehampton University in 2003 for the Prison Service. While the running speeds for the MSSRT and MSFT equate for each shuttle, the VO2Max levels do not. A level of 5.4 for the MSSRT equates to VO2Max of 31 while level 5.4 for the MSFT equates to a VO2Max of 35.
Attempts to validate the MSFT directly against the job requirements were undertaken by Brewer in 2004 for Lilleshall Consultancy Services (unpublished) where he compared physiological changes of heart rate and lactate production seen in control and restraint with the same changes in the MSFT, and considered level 5.4 of the MSFT to equate to the effort involved in control and restraint. This involved substantial variables that could not be readily controlled. Control and restraint is not a standard procedure like a firefighter lifting a ladder or even lifting a casualty. It would be very hard not only to define a standard control and restraint situation, but to replicate it effectively for research purposes.
A VO2Max level of 35 should therefore be considered a minimum for safety reasons, not the level required for control and restraint. It is, in essence, a safety test not a fitness test. The prison service use the MSFT as a safety test, not allowing the individual to progress to control and restraint training if they have failed to complete the test. The prison service adopted this standard in 2001. The Fire and Rescue Service have adopted the same standard as the minimum for operational firefighting. The police have introduced exactly the same test at level 5.4 as a minimum for safety reasons, following the Winsor report of 2011 (Winsor, 2012). Of note, the Canadian Correctional Services have introduced a similar fitness test which uses the MSSRT test with a cutoff at level 5.5.
The best source of standardised values for men and women can be found in the American College of Sports Medicine’s publication ‘Guidelines for Exercise Testing and Prescription’ which breaks down values into centile groups as follows:
Men VO2max (mL∙kg-1∙min-1)
Women VO2max (mL∙kg-1∙min-1)
Table 2. Population percentile values for cardiorespiratory fitness levels (VO2max in ml kg-1 min-1) with ageing (Thompson et al., 2010).
A major US study shows the typical decline seen in fitness with age, comparing men and women.
Figure 1. Age related changes in cardiorespiratory fitness in men and women, allowing for natural population change in smoking status, physical activity levels and body mass index with ageing (Jackson et al., 2009).
There is a clear difference between men and women, with men consistently having higher levels of fitness at all ages. However when the rate of decline is determined, this is almost identical.
Figure 2. Age related changes in cardiorespiratory fitness comparing men and women (Jackson et al., 2009).
The most important indication of the issues of lifestyle and fitness can be seen on the figure below, which incorporated evidence from a number of studies including UK firefighters. This compared those who maintained a level of fitness corresponding to around thirty minutes of exercise three times a week, and did not gain in weight with those who adopted a typical UK lifestyle gaining weight and not exercising.
Figure 3. Comparison between UK firefighters who maintain fitness and avoid weight gain with those whose lifestyle follows typical population trends (Williams et al., 2013).
Population studies clearly show that men have a higher aerobic fitness than women, therefore fewer women would be expected to meet the fitness standards required at recruitment. While this is arguably discriminatory, it can clearly be justified on health and safety grounds. Once they have been recruited, the decline in fitness should be no different between men and women, so there is no issue of gender bias. There is, however a subtle distinction. Many more men will be substantially above the minimum standard at recruitment while fewer women will be. It can therefore be argued that more women will join close to the minimum standard and will therefore be unable able sustain a fitness level sufficient to pass particularly from age 50 onwards.
Applying the fire service review to centile values gives two charts, one for those who follow typical population trends and a second for those who maintain fitness and avoid weight gain. It should be noted that the charts do not correspond to the ACSM values as the charts below represent two different populations, and the values for men and women have been combined.
Cardiorespiratory Fitness Level (VO2max in mL∙kg-1∙min-1)
Table 3. Estimated cumulative percentage of firefighters who follow typical population declines in physical activity and BMI who would be below the minimum VO2max standard recommended for operational duty (i.e. 35 mL∙kg-1∙min-1 shown in RED) and above the minimum recommended standard for operational duty (shown in GREEN).
Table 4. Estimated cumulative percentage of firefighters who maintain fitness and BMI who would be below the minimum VO2max standard recommended for operational duty (i.e. 35 mL∙kg-1∙min-1 shown in RED) and above the minimum recommended standard for operational duty (shown in GREEN).
Overall, the ACSM tables show that a VO2max standard of 35ml kg-1 min-1 will exclude less than 10-15% of men and 25-45% of women in the general population who apply for the role between ages 20 and 39. Once they have joined, the outcome will depend entirely on whether they maintain physical fitness and do not put on weight. If they follow typical population declines in fitness and increases in weight, then there will be a progressive increase in those who fail to meet fitness standards.
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THOMPSON, W. R., GORDON, N. F. & PESCATELLO, L. S. 2010. ACSM's Guidelines for Exercise Testing and Prescription, Baltimore, Lippincott Williams and Wilkins.
WILLIAMS, A. N., WILKINSON, D. M., RICHMOND, V. L. & RAYSON, M. P. 2013. Normal Pension Age for Firefighters: A review for the Firefighter's Pensions Committee. Department of Communities and Local Government.
WINSOR, T. P. 2012. Independent Review of Police Officer and Staff Remuneration and Conditions. In: OFFICE, H. (ed.).