Physical activity for adults (18-64 years)

This is an English summary of the Danish report: Fysisk aktivitet for voksne (18-64 år)

'Physical activity for adults (18-64 years) – knowledge about prevention and health benefits' presents the evidence on the association between physical activity, sedentary behaviour and health among adults aged 18-64 years. The report includes scientific literature from the Danish Health Authority (Sundhedsstyrelsen) and international systematic reviews conducted by research institutions and authorities from different countries: World Health Organization, USA, and Canada.

In the report the level of the evidence is described as strong, moderate, low, very low or insufficient. The indicated levels of evidence are based on the assessment made in the literature reviews that form the basis of the report. In these literature reviews, the level of evidence is based on an evaluation of the amount and quality of research in the area and whether there is consistency in the results of the studies. Strong evidence indicates great confidence in the observed relationship between physical activity and a given health outcome. In order to obtain strong evidence for an association, much research and several high-quality studies that point in the same direction is required. In the case of insufficient evidence, there is insufficient research to determine whether there is an association. Amongst other things, this may be because it has not yet been sufficiently investigated, which often characterizes new areas of research.

Physical activity and health

• There is strong certainty evidence that physical activity is associated to a lower mortality risk
• There is strong certainty evidence that physical activity reduces the risk of cardiometabolic diseases (e.g., cardiovascular disease and type 2 diabetes), obesity and weight gain
• There is moderate to strong certainty evidence that physical activity reduces the risk of breast cancer and colon cancer. Recent research shows that physical activity also reduces risk of other cancers such as bladder, endometrial, prostate, oesophageal, gastric and renals cancer.
• There is moderate certainty evidence that physical activity reduces risk of cognitive impairment and reduce the risk of development of anxiety and depression.

Dose-response relationship in relation to amount and intensity of physical activity

• There is high certainty evidence of a dose-response relationship where higher levels of physical activity (intensity, frequency and duration) are associated with lower risk of premature death and cardiometabolic diseases. Research shows that 150-300 minutes of physical activity of moderate intensity per week reduces the risks for premature death and cardiometabolic diseases considerable.
• There is moderate to high certainty evidence of a dose-response relationship between physical activity and breast and colon cancers where higher levels of physical activity reduces the risk of these types of cancers.
• There is very low to low certainty evidence of a dose-response relationship where higher levels of physical activity reduce risk of adiposity and decrease weight gain in adults
• There is insufficient evidence to describe the dose-response relationship between the volume of physical activity and the effect on cognitive function and mental health in adults.

Domain and type of physical activity

• There is moderate certainty evidence that physical activity undertaken in different domains (e.g. leisure, transport, occupational) has beneficial health effects. However, it is not possible to differentiate the effect of different domains of physical activity on various health outcomes.
• There is moderate certainty evidence that muscle-strengthening activities in combination with aerobic/cardiovascular activities of moderate to high intensity has additional health effects in adults. Muscle-training activities undertaken 2 or more days a week combined with regular aerobic/cardiovascular exercise of moderate to high intensity is associated with lower mortality compared to adults who only perform muscle-strengthening activities or aerobic/cardio training activities.
• There is insufficient evidence to describe and specify the combined volume of muscle-strengthening activities and aerobic/cardiovascular activities for optimal health benefits

Sedentary behaviour and health

Sedentary behaviour is a relatively new area of research that has received increased attention as more knowledge has emerged of the adverse effects of sedentary behaviour on health and the relation between physical activity and sedentary behaviour.

• There is moderate certainty evidence that sedentary behaviour increases risk of allcause mortality, cardiometabolic mortality and cancer mortality.
• There is moderate certainty evidence of an association between sedentary behaviour and higher incidence of cardiovascular disease and type 2 diabetes.
• There is low to moderate certainty evidence that sedentary behaviour increases risk of colon, endometrial, and lung cancers.
• There is low certainty evidence that sedentary behaviour increases risk of overweight, obesity, and unhealthy weight gain.
• There is insufficient evidence on the association between sedentary behaviour and cognitive function and mental health. Findings indicate that sedentary behaviour are related to an increased risk of developing depression and having a lower quality of life

Dose-response relationship and types of sedentary behaviour

• There is moderate certainty evidence of a dose-response relationship where higher volumes of sedentary time is related to increased risk of all-cause mortality and cardiovascular diseases. There is insufficient evidence to quantify frequency and/or duration of breaks in sedentary behaviour for a negative impact on health.
• There is insufficient evidence to describe a dose-response relationship between volume of sedentary behaviour and the effect on cancer, weight gain, cognitive function, and mental health, respectively.
• There is insufficient evidence to describe differences in risks depending on different types of sedentary behaviour (e.g., screen time or reading).

Sedentary behaviour and all-cause mortality in relation to physical activity level

There is moderate certainty evidence that physical activity of moderate to high intensity reduces the increased risk of all-cause mortality and cardiometabolic diseases due to sedentary behaviour.

Knowledge gaps and future perspectives

A national survey (National Health Profile 2021) show that more than half of adult Danes do not meet the WHO's minimum recommendation for physical activity, and about a fifth have sedentary leisure activities. In addition, there are clear differences in the level of physical activity in relation to age, gender, and socio-economic status. Most women (73.2%) and men (67.9%) who do not meet recommendations for physical activity wish to be more physically active. Therefore, it is important to support knowledge about how to motivate adults to take up and maintain a physically active lifestyle.

The stated amounts of physical activity in the existing systematic reviews are based on qualified estimates based on evidence in the field. In future research, there is a need to gain more knowledge about how high level of physical activity in combination with low sedentary time improves health among adults. In addition, there is still a lack of evidence about the health effects of sedentary behavior.