Walking in subzero winter temperatures puts extra strain on the heart of patients with coronary artery disease

Research carried out at the University of Oulu indicates that exercising in cold temperatures puts a greater strain on the heart of coronary artery disease patients than exercising in warm temperatures. No other unusual activity was observed in the cardiac and circulatory systems of men suffering from coronary artery disease while they were engaging in a half-hour brisk walk. 

Regular exercise all year round, and even in winter, is a key element for rehabilitation of coronary artery disease patients and helping them to maintain their health. However, cold environments are for these patients connected with symptoms of chest pain and cardiac arrhythmia, as well as such environments being associated with an increased risk of cardiovascular problems at the population level. In addition, it is also known that both cold conditions and exercise increases cardiac and circulatory strain, but little is known about their joint effects.

In order to provide safe, year-round exercise guidelines for coronary artery disease patients whose cardiac oxygen supply has been weakened and whose risk of vascular incidence has increased, it is important to understand the joint effects of cold temperatures and moderate, lengthy exercise carried out in line with the recommendations. This research assessed whether the cold environment affected the amount of work done by the heart and its function suggesting oxygen deficiency while brisk walking exercise was being carried out.

Participants of the research were 16 male coronary artery disease patients who had suffered an infarction of the heart from Oulu and the surrounding area with an average age of 60. The participants were brought into the laboratory in a random order, and engaged in either a resting or exercise (walking) task, which was performed either in cold conditions (-15°C with winter clothing) or at room temperature (22°C, light clothing). The blood pressure, pulse and ECG of the research subjects was measured during the tests.

The research indicated that the amount of work done by the heart was 17% greater for exercise in cold conditions than for exercise at room temperature. Nevertheless, no changes were observed in the ECG under cold conditions that would indicate oxygen deficiency in the heart. After the exercise, blood pressure returned to normal in the same way in both cold conditions and at room temperature.

These observations support the practice of year-round, health-promoting exercise even in climates which repeatedly expose people to cold conditions. The results can be applied to patients suffering from stable coronary artery disease. Further research will seek to establish how upper body exercise – designed to be equivalent to activities such as snow shovelling – impacts cardiovascular activity in those suffering from coronary artery disease. Taking into account the known cardiovascular health effects resulting from cold air, the researchers recommend further investigations that include individuals with more serious cases of coronary artery disease, or who have other chronic diseases, as well or who are also using other medication. The research data produced is beneficial for health care and rehabilitation professionals who are providing those suffering from coronary artery disease with safe exercise guidelines for winter conditions, and thus can promote the health and functioning of cardiac patients.

The research was carried out as part of a project led by the Center for Environmental and Respiratory Health Research (CERH) and supported by the Ministry of Education and Culture. The research was published in October 2018 in the American Journal of Physiology: Regulatory, Integrative and Comparative Physiology.

Valtonen RIP, Kiviniemi A, Hintsala HE, Ryti NRI, Kenttä T, Huikuri HV, Perkiömäki J, Crandall C, van Marken Lichtenbelt W, Alén M, Rintamäki H, Mäntysaari M, Hautala A, Jaakkola JJK, Ikäheimo TM. Cardiovascular responses to cold and submaximal exercise in patients with coronary artery disease. Am J Physiol Regul Integr Comp Physiol. 2018 Oct 1;315(4):R768-R776. https://doi.org/10.1152/ajpregu.00069.2018

More information:
Principal Investigator, Docent Tiina M. Ikäheimo, Center for Environmental and Respiratory Health Research (CERH), University of Oulu,
tiina.ikaheimo(at)oulu.fi, tel: +358 (0)40 5422 968

Last updated: 22.1.2019