There is much evidence of the health benefits of national adult physical activity guidance, but more research is needed on the duration of exercise and its impact on compliance. Matthew Adams appraises the evidence.
Within occupational health, the promotion of health is routinely conducted. Regardless of the clientele, clinicians will often give lifestyle improvement advice and promote the benefits of physical activity. While the Government promotes UK physical activity guidelines, you might have wondered about how appropriate the current physical activity guidelines are.
Although the national guidance targets large populations, this is the advice most commonly and correctly referenced by OH professionals. However, it is arguable whether or not such advice is applicable to everyone; suiting differing needs or abilities. This appraisal reviews the guidelines, and argues that OH clinicians need greater awareness to provide good physical activity advice.
Current physical activity guidelines for adults aged 19-64 years old in the UK
Over a week, activity should add up to:
- At least 150 minutes (2½ hours) of moderate intensity activity in bouts of 10 minutes or more.
- One way to approach this is to do 30 minutes at least five days a week.
- Alternatively, comparable benefits can be achieved through 75 minutes of vigorous intensity activity spread across the week or combinations of moderate and vigorous intensity activity.
- Adults should also undertake physical activity to improve muscle strength on at least two days a week.
(Department of Health, 2011)
One adverse aspect of the current format is that having multiple messages for physical activity and including the intensity types makes the message complex and difficult to interpret.
A review of the guidelines conducted by The British Heart Foundation Centre for Physical Activity and Health concluded that the latest evidence does support the volume of physical activity currently advised and the associated health benefits. However, it also argued that further reviews to allow for better reflection on the evidence of research accumulated since 2004 was needed (Bull et al, 2010).
Furthermore, the report added that physical activity guidelines should reflect that “higher volumes of activity (>150 minutes) are associated with even greater health benefits” (Bull et al, 2010, p.53). It is therefore clear that one simple message cannot encompass all the information that needs to be given. Some of the varying benefits to health will now be explored further.
One large base of evidence for current guidelines comes from the British Association of Sport and Exercise Sciences (BASES), which, in 2007, looked at evidence-based relationships between physical activity and various health outcomes (Tremblay et al, 2007). The associated health outcomes included the following:
- cardio-respiratory fitness;
- musculoskeletal fitness;
- cardiovascular disease risk;
- metabolic diseases;
- body composition;
- weight gain;
- bone health; and
- mental health issues.
There are multiple studies and evidence within literature for all these positively associated health outcomes directly linked to physical activity. However, in order to appraise the guidelines for the purpose of this article, it is the volumes of physical activity advised that will be discussed, and not the well-established outcomes of the exercise itself.
There is evidence showing that the volumes of moderate intensity activity required for different health benefits can vary. Moderate intensity activity for 120-150 minutes per week has been associated with: lower levels of all-cause mortality (Lee & Skerrett, 2001); type 2 diabetes (Gill & Cooper, 2008); cardiovascular disease mortality (Wannamethee & Shaper, 2001); and depression (Mutrie & Fox, 2010).
Conversely, significantly lower rates of breast cancer (Monninkhof et al, 2007), colon cancer (Samad et al, 2005), and obesity (Hill & Wyatt, 2005) were found in those doing 180-300 minutes per week of moderate intensity activity. Therefore, research advocates that there is no defined volume of exercise that can provide all of the fundamental benefits that can be obtained through activity.
Nevertheless, at present, no countries reflect these differing volumes of activity in their national physical activity guidelines. Primarily this is due to the added complexity and confusion that multiple health messages create.
Because of this, the Department of Health tries to retain within the primary message a single “dose” of activity, that has evidence of at least some of the health benefits to be had to prevent disease and ill health.
There are still relatively few studies that evaluate the health benefits in response to various volumes of activity. This is because volumes of activity need to account for the intensity, duration and frequency, which can be hard to quantify.
Duration of bouts of exercise
Conversely to Bull et al (2010) and the apparent increased health benefit of exercising for longer, the current guidelines also mention bouts of 10 minutes.
This dates back to 1995 and studies conducted by the American College of Sports Medicine (ACSM).
Current research also shows that 10-15 minute bouts, totalling 30-40 minutes a day can increase cardiovascular fitness, reduce adiposity, and improve blood pressure and lipid profile to a similar extent that the same volume of continuous exercise provides (Murphy et al, 2009). The advantage of this is not only that it is evidence based, but shorter bouts are easier to achieve among all population groups and especially for persons not conducting more structured forms of activity. This is why public health messages reflect this point in the guidelines.
The guidelines also mention the alternative of 75 minutes of vigorous activity each week. Again, research provides evidence for improvements to fitness (Duscha et al, 2005) and some health outcomes (Lee et al, 2005) with specifically vigorous activity.
However, most recent studies show that vigorous activity is only achieved by 20% of the population (Department of Health, 2010) and this form of exercise has been associated with increased risk of injury. So the risks of vigorous activity would vary between individuals, and with some would lead to low levels of compliance and therefore potentially reduced health benefits.
What is clear is that physical activity has many benefits to health, yet many are frequently overlooked. Even with the absence of weight loss, Esliger & Tremblay (2007) showed there is sufficient evidence that physical activity brings significant health improvements and reduces risk of heart disease, diabetes and even some cancers.
Equally, for those with poor compliance to physical activity, even low levels of activity below the national guidance do provide some health benefit compared with inactivity (Physical Activity Guidelines Advisory Committee, 2008).
As OH clinicians, a greater awareness of such issues raised in this appraisal is needed, as well as an understanding that current national guidance is not as clear cut and applicable to all as it seems.
An awareness that the Government guidance targets healthy adults is vital. For those with varying levels of physical needs, or special health issues, physical activity advice should be tailored accordingly.
Equally there needs to be greater awareness that there are varying health benefits to be had dependent upon the type, frequency, duration and intensity of physical activity performed. As a result, the advice given by OH clinicians needs to be based on national guidelines but adapted to suit the individual.
A clinical judgement based upon an individual’s health needs, risk factors and ability to be physically active will need to play a greater part in the advice given.
Matthew Adams is OH adviser at Managed Occupational Health Ltd.
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