** NEW** UK Chief Medical Officers’ Physical Activity Guidelines

Since publication of the previous physical activity guidelines in 2011, the scientific evidence on the relationships between physical activity and health has continued to accumulate, including new evidence on the volume, duration, and frequency of physical activity for substantial health benefits for all adults.

Each week, adults should accumulate at least 150 minutes (2 1/2 hours) of moderate intensity activity; or 75 minutes of vigorous intensity activity; or even shorter durations of very vigorous intensity activity; or a combination of moderate, vigorous and very vigorous intensity activity.

The previous guidelines (2011) recommended that adults should undertake 150 minutes per week of moderate intensity physical activity (MPA) or 75 minutes of vigorous intensity physical activity (VPA) or a combination of the two, and resistance training two or more times per week, to gain a range of physical and mental health benefits, and to reduce the risk of many non-communicable diseases. They recommended that physical activity should be spread throughout the week by being active on most days and accumulated in bouts of 10 minutes or more.

However, more recent evidence suggests that these 150 minutes can in fact be accumulated in bouts of any length, and/or achieved in one or two sessions per week while still leading to health benefits. In addition, it suggests that health benefits may also be derived from lower volumes, intensities and frequencies of activity, particularly for individuals with low levels of physical fitness and for disabled adults. Further new evidence suggests that short duration, very vigorous exercise (at or close to all-out or maximal effort) at lower volumes than 75 minutes per week may bring equivalent health benefits to those derived from adherence to the previous guidelines, in a more time-efficient manner.

Improving fitness also further reduces the risk of cardiovascular disease beyond the reduction associated with regular physical activity. The evidence continues to suggest that at least twice a week, all adults should undertake activities which increase or maintain muscle strength (resistance training). The activities chosen should use major muscle groups in the upper and lower body. This can include activities such as using bodyweight, free weights, resistance machines or elastic bands, as well as activities of daily living such as stair climbing, wheeling your wheelchair, carrying shopping bags, lifting and carrying children, and gardening.

Physical activity expends energy…

…and therefore makes a valuable contribution to weight management by reducing adiposity. The evidence reviewed suggests that greater than 150 minutes of physical activity, together with dietary restriction, may be required for weight loss. Given the interdependency of energy intake and expenditure for weight loss, it is not possible to specify how much more physical activity alone would be likely to result in weight loss. However, given the scale of the problem of overweight and obesity, the importance of physical activity and the need to simultaneously restrict energy intake should be emphasised. Moreover, the role of physical activity in maintaining weight following weight loss should be highlighted. It is also worth emphasising that the health benefits associated with physical activity are experienced by adults irrespective of weight status, and in the absence of weight loss.

Dose-response relationship varies by disease risk…the research…

Often increases in the volume of physical activity bring additional reductions in risk.

For example, for hypertension, the evidence suggests that 150 minutes (10 MET-h) of ‘leisure time PA’ reduces the risk of hypertension by 6%, with further reductions of a similar magnitude for every additional 150 minutes.

For type 2 diabetes, dose-response analysis indicates that risk reduction can be achieved below 150 minutes of MVPA per week, but that substantially greater benefits can be achieved by being more active.

For cardiovascular disease (CVD), recent evidence suggests that achieving the current guidelines is associated with reduced risk, but that moving from inactive to moderately active (6 MET-h per week, or less than half of the guideline amount) brings proportionately the greatest benefit.

There have been notable developments in the epidemiological evidence base for adults, particularly regarding associations between sedentary behaviour and cancer risk and survivorship. Recent meta-analytical data from 34 studies, including over one million unique individuals, concluded that for adults, above 6 to 8 hours per day of total sitting time and 3 to 4 hours per day of TV viewing time are associated with greater risk of all-cause and CVD mortality, independently of levels of MVPA. Despite these new studies, there currently remains insufficient evidence to determine a dose–response relationship or a threshold for clinically relevant risk. At present the evidence therefore does not support including a specific time limit or minimum threshold of sedentary time within this recommendation. New evidence on the health benefits of shifting from sitting to standing was insufficient to support including a recommendation to interrupt sedentary time by standing.

For good physical and mental health, adults should aim to be physically active every day. Any activity is better than none, and more is better still.

• Adults should do activities to develop or maintain strength in the major muscle groups. These could include heavy gardening, carrying heavy shopping, or resistance exercise. Muscle strengthening activities should be done at least two days a week, but any strengthening activity is better than none.
• Each week, adults should accumulate at least 150 minutes (2 1/2 hours) of moderate intensity activity (such as brisk walking or cycling); or 75 minutes of vigorous intensity activity (such as running); or even shorter durations of very vigorous intensity activity (such as sprinting or stair climbing); or a combination of moderate, vigorous and very vigorous intensity activity.
• Adults should aim to minimise the amount of time spent being sedentary, and when mphysically possible should break up long periods of inactivity with at least light physical activity.

To read the full report click here

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