Author + information
- aRadboud Institute for Health Sciences, Department of Physiology, Radboud University Medical Center, Nijmegen, the Netherlands
- bResearch Institute for Sports and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
- ↵∗Address for correspondence:
Dr. Thijs M.H. Eijsvogels, Department of Physiology (392), Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, the Netherlands.
The cardiovascular health benefits of a physically active lifestyle are well recognized and frequently described (1,2). Nevertheless, physical inactivity remains a global problem, particularly in clinical populations such as coronary heart disease (CHD) patients. A recent meta-analysis including >1,000,000 individuals found that individuals who are inactive and sit the most have the highest risk for mortality (3). The typical CHD patient fits this description as she or he usually performs little regular exercise and sits much of the time. Strategies to increase physical activity (PA) and decrease sitting in high-risk populations such as CHD patients are therefore needed. Current guidelines prescribe similar PA recommendations for primary (4) and secondary prevention (5,6): 150 min/week of exercise at a moderate intensity. Most evidence for the health benefits of exercise in CHD patients are derived from cardiac rehab studies (7). Although these findings support the benefits of regular PA, these studies do not inform on the minimal dose, optimal dose, and potential upper limit of PA to reduce cardiovascular morbidity and mortality.
In this issue of the Journal, Stewart et al. (8) describe the association between self-reported PA and mortality in 15,486 patients with stable CHD who participated in the STABILITY (Stabilization of Atherosclerotic Plaque by Initiation of Darapladib Therapy) trial. Patients from 39 countries were allocated to tertiles of PA. The intermediate and most active tertile had a lower risk for all-cause mortality (hazard ratio [HR]: 0.75; 95% confidence interval [CI]: 0.65 to 0.87, and HR: 0.70; 95% CI: 0.60 to 0.82), cardiovascular mortality (HR: 0.89; 95% CI: 0.74 to 1.06, and HR: 0.71; 95% CI: 0.58 to 0.88), and noncardiovascular mortality (HR: 0.54; 95% CI: 0.41 to 0.72, and HR: 0.73; 95% CI: 0.55 to 0.96) compared with the least active tertile. The most active tertile also had a lower risk for major adverse coronary events (HR: 0.81; 95% CI: 0.71 to 0.92), whereas there were no differences in the risk for myocardial infarction and stroke across all tertiles. The dose-response analysis showed a curvilinear relationship between PA and mortality with the largest risk reductions at the beginning of the curve. Furthermore, the PA-associated reductions in mortality were greater among CHD patients, whose exercise was limited by dyspnea and in those with a high STABILITY CHD risk score, suggesting that high-risk patients benefit the most from a physically active lifestyle.
This study provides important insight in the health benefits of exercise training and habitual PA in CHD patients. Data from Stewart et al. (8) suggest that as little as 10 min/day of brisk walking (i.e., 3.5 mph) is associated with a 33% risk reduction for all-cause mortality. For those unable to walk at a brisk pace, 15 to 20 min/day at a slower pace (2 to 2.5 mph) will yield similar benefits (8). These findings suggest that CHD patients reduce their mortality risk by performing PA volumes below current recommendations. The low volume of this minimal effective dose may stimulate patients to incorporate feasible PA goals in their daily lives and may also eliminate barriers, such as insufficient time or self-confidence, to become physically active.
An important limitation of the study by Stewart et al. (8) is that questionnaires were used to assess PA. Questionnaires, including the International Physical Activity Questionnaire, overestimate PA volumes, and there is poor agreement between objective (accelerometers) and self-reported PA (9). Average PA volume in the present study was 40 metabolic equivalents (METs) h/week, which is equivalent to 3.5× to 4× current PA recommendations and can be translated to 10 h of walking per week. It is unlikely that the STABILITY patients were so active, because a recent review found that 41 METs h/week is the optimal PA volume to reduce cardiovascular events in the general population (10). A potential explanation for the high PA volumes may relate to the inclusion of low-intensity and work-related activities, because most epidemiological studies include moderate to vigorous intensity PA only (11). Nevertheless, we can assume that the PA-related health benefits start at lower PA volumes than those estimated in the present study.
The greatest reductions in mortality risk were found in the most active patients. These observations align with dose-response analyses in the general population (11,12) and suggest that high volumes of PA do not increase mortality risks. Although similar data were reported in a Norwegian cohort of CHD patients (13), studies in American heart attack survivors (14) and British (15) and German (16) CHD patients found attenuated health benefits in the most active group. Differences in study methodology and follow-up duration may contribute to these discrepancies. Furthermore, it is important to emphasize that patients in the STABILITY trial mainly performed low- to moderate-intensity PA, whereas vigorous-intensity PA is known to transiently increase the risk for sudden cardiac death, especially in previously inactive patients (17). Therefore, findings from Stewart et al. (8) do not exclude the possibility that extreme PA may worsen cardiovascular outcomes for CHD patients.
Regardless of the PA volume, patients who performed any vigorous-intensity PA had a lower mortality risk compared with those performing only low- or moderate-intensity PA. High-intensity interval training is also increasingly applied to cardiac rehabilitation programs, and a recent meta-analysis showed that high-intensity interval training produces greater increases in cardiopulmonary fitness compared with traditional moderate-intensity exercise training (18). The superior health benefits of vigorous PA have been established in the general population previously (10,19), and Stewart et al. (8) suggest that these findings can be extrapolated to the CHD community.
In summary, findings from this large-scale study among CHD patients demonstrate that low volumes of PA are associated with large risk reductions for all-cause and cardiovascular mortality. Increasing volumes of PA yield additional health benefits, but the absolute decrease in mortality risk becomes smaller for every doubling of PA volume. Vigorous intensity PA was associated with the lowest mortality risk, suggesting that patients benefit most from this type of exercise. These novel insights inform us about effective exercise regimens for secondary prevention, but require confirmation from additional studies. In the interim, patients and clinicians should remember that a little is good, more is better, and vigorous is best.
↵∗ Editorials published in the Journal of the American College of Cardiology reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology.
Dr. Eijsvogels is supported by a European Commission Horizon 2020 grant (Marie Sklodowska-Curie Fellowship 655502). Dr. Maessen is financially supported by an INTERREG VA grant (203072/WP1).
- 2017 American College of Cardiology Foundation
- ↵Physical Activity Guidelines Advisory Committee. Physical Activity Guidelines Advisory Committee Report. Washington DC, U.S.: Department of Health and Human Services. 2008. Available at: https://health.gov/paguidelines/report/pdf/CommitteeReport.pdf Accessed July 27, 2017.
- Fihn S.D.,
- Gardin J.M.,
- Abrams J.,
- et al.
- O’Gara P.T.,
- Kushner F.G.,
- Ascheim D.D.,
- et al.
- Anderson L.,
- Oldridge N.,
- Thompson D.R.,
- et al.
- Stewart R.A.H.,
- Held C.,
- Hadziosmanovic N.,
- et al.,
- on behalf of the STABILITY Investigators
- Dyrstad S.M.,
- Hansen B.H.,
- Holme I.M.,
- Anderssen S.A.
- Eijsvogels T.M.,
- Molossi S.,
- Lee D.C.,
- Emery M.S.,
- Thompson P.D.
- Wannamethee S.G.,
- Shaper A.G.,
- Walker M.
- Mons U.,
- Hahmann H.,
- Brenner H.