Physical activity guidelines, based on the available scientific evidence, claim that achieving recommended activity levels will substantially improve individual and population lifespan and health. [1,2] Engaging in regular physical activity may, therefore, be one of our best “life-enhancing medicines” and should be used extensively. 

The sceptics of using exercise as medicine argue that the literature lacks high-quality evidence on the effect of exercise on hard endpoints. Indeed, whether physical activity actually reduces mortality has never been tested in a randomized setting, nor have the effects of different exercise intensities. With these challenges in mind, The Cardiac Exercise Research Group at the Norwegian University of Science and Technology launched the Generation 100 study in 2011. The Generation 100 study is the longest and largest randomized controlled exercise trial evaluating the effect of supervised exercise training versus physical activity recommendations on mortality in older adults.  

Ideally, such a study should cover all ages of adulthood. However, due to the need for a large sample size, and long and costly follow-up time, we decided to focus on older adults. This is a rapidly growing population, and the higher death rates among older adults, make this population particularly interesting for testing whether there is a causal relationship between current physical activity levels and longevity. This is the first randomized controlled study examining the effect of long-term aerobic exercise on all-cause mortality compared to controls being asked to follow the physical activity guidelines in a general population of older adults. Importantly, our data demonstrate larger health benefits in those that undertook mainly high intensity exercise when compared to those that mainly undertook exercise with moderate intensity. We therefore suggest that future guidelines for physical activity, at least for older adults, should be more specific in requiring that at least part of the physical activity should be performed with high intensity.

Older adults are often ignored or underrepresented as study participants in clinical research studies. For us it has been an enrichment to see how dedicated and grateful the participants have been to be included in a long-term randomized clinical study. Our participants regularly said that they were honored to contribute to research that can impact and benefit society. Importantly, despite the fact that the study ran over five years, the drop-out rate was low, and comparable to many short-term exercise interventions. We think that one of the main reasons for the relatively low drop-out rate is that we succeeded in finding a balance between a real-life setting and being able to control the interventions. We did not want to exclude people who preferred to exercise on their own. Combining a mandatory exercise programme, in addition to offering two weekly supervised exercise session was a success. Retrospectively, this combination was of great significance, as almost 50% of the participants reported that they exercise mostly on their own. Nevertheless, the real-life setting was challenging, as we lacked the tools for accurate tracking of exercise. The use of questionnaires was a suitable tool to access physical activity with moderate and high intensities when we initiated the study. However, with the technology available today, where numerous exercise and physical activity tracking tools exist, enabled researchers to collect objective and detailed information about exercise sessions outside the lab in future studies. 

Importantly our study indicates that a yearly follow up of older adults that includes a focus on the importance of physical activity, can motivate them to stay physical active. This finding should have an impact on our healthcare service, and we believe that GPs can play a more significant role in motivating older adults to take better care of themselves simply by asking specific questions about their physical activity level. Our study revealed a serious challenge in finding a suitable control group in life-style interventions. People signing up for studies looking at the effect of life-style changes, are in general healthy and/or very motivated to change lifestyle. Hopefully the experience from our study empowered researchers to look for new concepts in regard to suitable control groups in randomized controlled lifestyle trials in the future.

Dorthe Stensvold, professor, The Cardiac Exercise Research Group (ntnu.edu/cerg) at The Norwegian University of Science and Technology

Ulrik Wisloff, professor, The Cardiac Exercise Research Group (ntnu.edu/cerg) at The Norwegian University of Science and Technology

Oivind Rognmo, associate professor, The Cardiac Exercise Research Group (ntnu.edu/cerg) at The Norwegian University of Science and Technology

Competing interests: See research paper for full declaration.

References:

1. Piercy KL, Troiano RP, Ballard RM, et al. The Physical Activity Guidelines for Americans. JAMA. 2018;320:2020-2028.
2. Thompson PD, Eijsvogels TMH. New Physical Activity Guidelines: A Call to Activity for Clinicians and Patients. JAMA. 2018;320:1983-1984.
3. Wen CP, Wai JP, Tsai MK, et al. Minimum amount of physical activity for reduced mortality and extended life expectancy: a prospective cohort study. Lancet. 2011;378:1244-1253.
4. Anderson L, Thompson DR, Oldridge N, et al. Exercise-based cardiac rehabilitation for coronary heart disease. Cochrane Database Syst Rev. 2016:CD001800.