High-intensity exercise – a tool for improved public health?

Physical inactivity is the fourth leading risk factor for global mortality. Recent reports from England and the United States indicate that physical inactivity is the most common risk factor for chronic disease given that 95% of the adult population does not comply with their national recommendations of physical activity. 

D-eldre1Population-based strategies, aimed at reducing general risk factor levels through lifestyle and environmental changes, are considered to be the most cost-effective and sustainable approaches for reducing the rates of mortality and morbidity. The rationale is that a moderate lowering of risk across a large number of people will have a bigger public health impact than large risk reductions among the few at high risk. However, one of the lessons from previous large community health interventions is that when you try to do too much with too many people, the focus of the program may be lost, the dose per person is low, and the outcomes are often disappointing. The majority of projects have shown only modest impacts on the prevalence non-communicable diseases (NCDs) and its risk factors at the community level.

There is massive evidence that physical activity is associated with reduced risk of NCDs such as cardiovascular disease, diabetes, high blood pressure, many different types of cancer, asthma, arthritis, osteoporosis and Alzheimer’s disease, to mention some. Individuals with at least average cardiorespiratory fitness (CRF) live longer than those with lower fitness, and even small changes in fitness can provide significantly increased life expectancy. Results from the HUNT survey including over 56 000 men and women showed that one vigorous workout a week was associated with a 39% reduction in mortality for men and 51% reduction in mortality for women. In another study involving 416 175 individuals, physical activity for 15 min a day or 90 min a week provided a reduction in all-cause and all-cancer mortality and extended an individual’s lifespan for an average of 3 years. This minimum amount of exercise was found to be applicable to men and women of all ages, even those with cardiovascular diseases or lifestyle risks.

Research also point to that high intensity training, such as interval training, is superior to that of training with low and moderate intensity with respect to its preventive effect, both in health and disease. Actually, in patients with heart failure, an improvement of the hearts pump function has only been found after high-intensity exercise training. Interestingly, it seems that most of the effect of aerobic training is attained when the high-intensity threshold is passed for only a few minutes, and with only one exercise bout. Thus, interval training can be an effective way to implement high exercise intensity in the general population, and we believe there is sufficient empirical support to use high intensity exercise to promote health in a coordinated population-based intervention to maximize cardiorespiratory fitness. In line with this, WHOs report on global recommendations on physical activity for health emphasizes the central role of high intensity exercise.

In a recent review article, we argue that the high prevalence of chronic diseases, increasing obesity and inactivity, rising health expenditure and the increasing proportion of elderly people in our society represent a set of developments that cannot be considered sustainable, and will have dire long-term consequences. Increased physical activity has a beneficial effect on all risk factors for NCDs and premature death. A coordinated population-based intervention program for improved health through increased physical activity in the entire population urgently needs to be implemented. High intensity exercise should be emphasized as the health benefits seem to be larger with high intensity training, specifically forms of interval training.

Tommy A. Rehn

Tommy A. Rehn

The question is how a sufficient level of high intensity physical activity can be attained in all strata of the population. In contrast to most previous large-scale population-based intervention programs, we believe that introducing a single focus, namely increased physical activity with high exercise intensity, will improve the chance of a successful intervention. It is crucial that the intervention has an effect on the inactive individuals, regardless of age, and that there is a strong focus to intervene from childhood as this would have the greatest potential in a long perspective. Such a coordinated population-based intervention could demonstrate positive effects of increased physical activity on public health by reducing the prevalence of NCDs, reducing medical expenses and mortality, as well as increasing work capacity in the population, which in turn would reduce socioeconomic costs. This could form the basis for national and international implementation of health policies.

Tommy Aune Rehn, general practitioner at Levanger Legesenter, PhD in cardiology and exercise physiology.

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About CERG

The Cardiac Exercise Research Group (CERG) at the Norwegian University of Science and Technology (NTNU) seeks to identify the key mechanisms underlying the beneficial effects of physical on cardiac health in the context of disease prevention and treatment. Named the K.G. Jebsen Center for Exercise in Medicine under Professor Ulrik Wisløff's leadership in 2011, CERG uses both top-down and bottom-up approaches to combat lifestyle-related disease.

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