Physical activity - manual on disease prevention and treatment

Report in Danish (13 December 2018, 494 pages): Fysisk aktivitet - håndbog om forebyggelse og behandling

Summary

Physical activity in preventing disease

There is a consensus that physical activity promotes health and prevents many diseases. Children who have relatively high levels of various risk factors for cardiovascular disease and who engage in increased physical activity reduce these levels (including overweight). This mostly applies to aerobic activity, but strengthtraining activity also has an independent effect. The quartile of children who have the poorest physical fitness have a 15-fold greater risk of elevated cardiovascular risk factors. Strength-training activities positively affect bone development in addition to cardiovascular risk factors.

Children’s physical activity has received increased attention in recent years because many of the health conditions physical activity prevents, such as obesity, are easier to prevent than to treat. No precise data indicate whether the level of physical activity among children in Denmark has changed in recent decades. Studies of children’s physical fitness show an increasing gap between the children with the best and worst fitness. From a health perspective, it is not a priority that the children with the best physical fitness improve, but it is a serious problem that the children with the worst physical fitness are getting worse. This observation probably results from reduced daily physical activity and physical play among part of the population.

The greatest challenge is activating the least physically active people. Recent research shows that interventions targeting children with obesity are effective, and more physical education classes in the school curriculum are effective at improving the health status of the most vulnerable children.

Epidemiological studies among adults consistently show that physically active people have lower morbidity and mortality. The risk is nearly halved among the most physically active people. Increasing physical activity is associated with reduced morbidity and mortality even among middle-aged and older people. Epidemiological cohort studies generally underestimate the effects of physical activity because they normally analyse everyone based on the level of activity they had when the study started, and everyone who changes their level of physical activity during the follow-up period is thereby incorrectly categorized. The diseases for which evidence demonstrates conclusively that physical activity has a preventive effect include heart disease, type 2 diabetes, metabolic syndrome and cancer of the colon, but many other conditions and diseases such as osteoporosis, depression, dementia and cancer of the prostate, testicles, lungs and breasts are also clearly associated with physical activity.

The effect of physical activity in preventing premature death applies to both sexes and all age groups and regardless of the presence of overweight or other risk factors. The manual reviews some of the classical studies and studies carried out in the Nordic countries. Physical activity among older people has the same preventive effects as among younger adults, but physical activity also considerably improves their functioning, which is especially important in maintaining normal activities of daily living and their quality of life. Older people generally have lower physical reserve capacity than younger people, which means that the activities of daily living comprise a great burden. Older people have at least the same proportional potential as younger people to improve their physical performance, and exercise training can therefore substantially affect their functional capacity. Further, increasing muscle strength among older people reduces their risk of falling and thereby their risk of osteoporotic fractures.

Physical activity has the same health-promoting effects among pregnant women as among non-pregnant women of the same age. High-intensity aerobic physical activity (condition training) provides benefits before, during and after pregnancy. Women who have been very physically active before pregnancy can continue to be physically active during pregnancy, perhaps with a slightly lower intensity and quantity, as long as they are otherwise healthy. High-impact physical activity may increase the risk of abortion early in pregnancy. Strength training in a sitting position with light weights or a light load in training with machines provides benefits during pregnancy. Women who have engaged in strenuous strength training before pregnancy may continue this training during pregnancy as long as they are otherwise healthy. Non-weight-bearing physical activity is recommended for women with back or pelvic pain and is generally recommended for all pregnant women late in pregnancy.

Pregnant women who have a high risk of gestational diabetes or pre-eclampsia and eclampsia should engage in a higher quantity and intensity of physical activity. Pregnant women may prevent urinary incontinence by training the pelvic muscles during pregnancy.

Exercise training as treatment

Substantial evidence has been gathered in the past two decades on the role of exercise training in treating numerous diseases, including diseases other than musculoskeletal disorders. Exercise training is currently indicated for treating many diseases. Medicine traditionally prescribes the treatment that scientific studies have shown is most effective with the fewest side effects or risks. Evidence now indicates that exercise training in selected cases is just as effective or, in special cases, even more effective than pharmaceutical treatment or has an additive effect when combined with pharmaceutical treatment.

The manual presents an evidence-informed basis for exercise training in treating 31 diseases. The borderline between exercise training as prevention and as specific treatment is fluid in some cases. For example, this applies to hypertension, hyperlipidaemia, overweight and metabolic syndrome, which may all be considered risk conditions rather than diseases. The manual includes these diagnoses, since there is a tradition of or consensus around offering prophylactic pharmaceutical treatment and evidence of an effect of physical activity and physical training.

Exercise training may have clinical effects by directly influencing disease pathogenesis (such as in intermittent claudication and ischaemic heart disease), by improving the predominant symptoms of the underlying disease (such as in chronic obstructive lung disease) or by improving fitness and strength and thereby the quality of life among people who are weakened by disease (such as cancer). Some diseases may comprise a barrier to being physically active, such that the person with the disease does not achieve the positive effects of preventing other diseases. There are guidelines on how such people can be physically active (such as people with type 1 diabetes and asthma). In the first section “Konklusion og træningstype” for each of the 31 diseases the manual describes the level of evidens and the recommended kind of exercise training.

Recommendations for physical activity

The manual presents recommendations for physical activity in Denmark in accordance with the international recommendations for physical activity. The recommended quantities are based on a qualified estimate informed by evidence in this field. The recommendations are based on educational considerations and the desire to maintain motivation for physical activity among the specific groups desired to be engaged. The aim is to activate the people who are currently least physically active.