A study shows, for the first time, that people with cardiovascular disease benefit more from exercise than healthy people.
However, no studies had looked at how exercise really benefits individuals who already have cardiovascular disease.
Now, for the first time, researchers — many from Seoul National University, in South Korea — have compared the effects of exercise on the risk of death in a cohort of healthy participants and a cohort of participants with preexisting cardiovascular disease.
The study revealed that individuals with cardiovascular disease seemed to benefit more from exercise than healthy individuals — and the more they exercised, the better.
The team, led by Dr. Sang-Woo Jeong, published the findings in the European Heart Journal last week and also presented them at the European Society of Cardiology (ESC) Congress 2019, held in Paris, France.
14% death risk reduction over 6 years
Dr. Jeong and colleagues analyzed the data of 441,798 participants, who were part of the Korean National Health Insurance Services Health Screening Cohort.
Of these, 131,558 participants had preexisting cardiovascular disease, while 310,240 were healthy. All of the participants were aged 40 or over, with an average age of 60. All had taken part in a health screening program between 2009 and 2015 and had provided information about their levels of physical activity.
In their analysis, the researchers also had access to follow-up data for nearly 6 years, as well as information regarding death and its cause, accessed through the Korean National Death Index.
The participants provided information on their levels of physical activity via surveys that asked them to report how often they had been physically active in the past week. In this case, physical activity referred mainly to instances of aerobic exercise and did not include daily activities, such as housework.
The researchers converted these data into units of metabolic equivalent task minutes per week (MET-mins/week), which allowed them to quantify levels of activity.
Dr. Jeong and the team found that, after the 6-year follow-up period, the participants with cardiovascular disease had benefitted more from physical activity than the healthy participants.
More specifically, for every 500 MET-mins/week, healthy individuals saw a 7% reduction in premature death risk, while those with cardiovascular disease saw a 14% death risk reduction.
Among healthy individuals, those who saw the most benefits were those who undertook 0–499 MET-mins/week of exercise. The benefits were less significant for healthy people who undertook 500–1,000 MET-mins/week, only increasing again after the 1,000 MET-mins/week landmark.
As for participants with cardiovascular disease, once more, individuals who undertook 0–499 MET-mins/week of exercise saw the most significant benefits. However, in this cohort's case, risk reduction continued to rise beyond the 500 MET-mins/week point.
Yet, at the same time, the researchers noted that almost 50% of all participants exercised very little, and about 25% of participants reported no physical activity.
"We found that approximately half of the people in the study did not reach the recommended level of leisure-time physical activity, and a quarter had a totally sedentary lifestyle," says Dr. Jeong.
"People with cardiovascular disease had lower levels of physical activity than those without, but the more exercise people did, the lower their risk of death during the 6 years of follow-up. The main new finding of this study is that people with cardiovascular disease benefit from a physically active lifestyle to a greater extent than healthy people without cardiovascular disease," Dr. Jeong explains.
How to reach desired activity levels
As to why individuals with cardiovascular disease derive greater benefits from exercise than healthy individuals, the researchers can only make conjectures.
"There may be several plausible explanations for why people with [cardiovascular disease] benefited the most from exercise. First, sedentary lifestyle is a well-known risk factor for [cardiovascular disease]. Patients with [cardiovascular disease] may have had sedentary lifestyles, and thus, changing their lifestyle to become more physically active may be more beneficial," notes study co-author Dr. Si-Hyuck Kang.
"Secondly," he adds, "a number of previous studies have shown that physical activity helps control cardiovascular risk factors such as blood pressure, cholesterol, and blood glucose. The benefit of physical activity in secondary prevention may come by better controlling such risk factors."
"Lastly, patients with [cardiovascular disease] usually have higher levels of systemic inflammation than those without [this condition], and there is evidence that physical activity lowers systemic inflammatory levels," Dr. Kang explains.
The researcher also goes on to advise that doctors encourage individuals with cardiovascular problems not to give up on exercise and explain just how physical activity can benefit health.
"The 2016 ESC guideline for primary prevention recommends healthy adults of all ages should perform at least 150 minutes a week of moderate intensity or 75 minutes a week of vigorous intensity aerobic physical activity, or an equivalent combination," Dr. Kang notes.
"One way you can achieve 500 MET-minutes a week is to do brisk walking for 30 minutes, five times a week. If you are very busy [...], the other way to achieve approximately 500 MET-minutes a week is to do vigorous physical activity, such as climbing hills with no loads, for 75 minutes, once a week."
Dr. Si-Hyuck Kang
"You can achieve 1,500 MET-minutes a week by doing brisk walking for 30 minutes, five times a week, plus climbing hills for 2.5 hours, once a week," Dr. Kang also suggests.