Written by: Irene Euodia
Medically reviewed by: Robert Philibert MD PhD
How Much Movement Is Enough?
The New York Department of Health estimates that 35% of the ~700,000 coronary heart disease deaths in the United States each year are due to physical inactivity. The level of physical activity in adults is a strong independent indicator of coronary heart disease risk. These findings raise concerns in many of us to increase our level of exercise. But, how much “dose” of “activity” do we actually need to prevent heart disease?
Defining Physical Inactivity, Sustained, and Vigorous Activity
“Physical inactivity” also known as being sedentary, is a term used to identify people who do not get the recommended level of regular physical activity. The American Heart Association recommends 30-60 minutes of aerobic exercise three to four times per week to promote cardiovascular fitness. Sustained physical activity usually means activity of any intensity lasting 30 minutes or more 5 times a week. Moderate activity increases your heart rate to 50-70% of its maximum recommended rate. Vigorous activity is an activity intense enough to make the heart beat fast (70-85% of its maximum recommended rate) for at least 20 minutes, 3 times a week. But before embarking on an exercise regimen, use caution. Consider consulting a clinician because not everyone’s exercise tolerance is the same and one does not want to invite a cardiac event by engaging in an exercise routine beyond the safe limits.
Why Should We Care?
Physical inactivity alters the risk for coronary heart disease by modulating the effect of other “classic” risk factors such as obesity, hypertension, and smoking, on endothelial function (Winzer, 2018). The endothelium is the innermost lining of our blood vessels and plays a vital role in ensuring the delivery of oxygen and nutrients to all tissues. At the molecular level, endothelial functions include promoting the growth of preexisting coronary vessels, rejuvenating the endothelium (heart lining), and decreasing the production of reactive oxygen species (toxic substances to cells) (Winzer, 2018).
These molecular signaling pathways are critical to understanding how exercise affects heart health. Studies have shown the part of the protective effects of physical activity is mediated by the secretion of cytokines during skeletal muscle contraction. These cytokine messengers may trigger specific metabolic pathways in different tissues, including the endothelium, as well as other organs and tissues such as visceral fat, bone, liver, and nervous system. Some cytokines may work exerting specific endocrine effects on visceral fat metabolism and anti-inflammatory functions through signaling pathways involved in fat oxidation (So et al., 2014). So, when there is no muscle contraction, visceral fat accumulates, which again, is one of the sources of systemic inflammation and is recognized as one of the leading risk factors for developing dozens of chronic diseases (Booth et al., 2012).
Past Studies
In a study published in 2002, researchers analyzed the relationship between occupational activity and leisure time in 40,000 people over 12 years of time. They found that there was a dose-dependent relationship between exercise and coronary heart disease incidents. This trend of association remained constant regardless of any major exercise types such as swimming, jogging, and cycling. However, it is important to note that vigorous exercise in untrained individuals elevates the risk for coronary heart disease.
How Much Physical Activity Do We Need?
The best “dose” of physical activity is a combination of duration, intensity, and frequency of exercise. It is recommended that adults engage in moderate-intensity physical activities (defined as those activities that lead to notable increases in heart rate and breathing) for at least 30 minutes per day, five days per week. Alternatively, adults can engage in vigorous-intensity activities, which cause rapid breathing and substantial increases in heart rate for 20 minutes per day at least 3 days per week. The ideal physical activity program represents a combination of both moderate- and vigorous-intensity physical activities in bouts lasting at least 10 minutes per session. Specific recommendations vary for older adults and children and whether the goal is weight loss, weight maintenance, or disease prevention (Carnethon, 2009). All recommendations share components that address the frequency, intensity, and duration of activities. Please consult with your health care provider to help tailor your personalized needs.
In brief, regular exercise provides many benefits for your health, especially coronary heart disease prevention. It is important to remember, that although exercise is one major intervention, other aspects of health such as diet and sleep also play important roles to achieve synergistic results. Don’t forget to consult a clinician and start exercising regularly!
References:
- Physical Activity and Cardiovascular Disease: How Much is Enough? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2857374/
- Effects of Physical Inactivity in Cardiovascular Biomarkers, https://jlpm.amegroups.com/article/view/5639/html
- Physical Activity in the Prevention and Treatment of Coronary Artery Disease, https://www.ahajournals.org/doi/10.1161/JAHA.117.007725
- Physical Inactivity and Cardiovascular Disease, https://www.health.ny.gov/diseases/chronic/cvd.htm
- Exercise-induced myokines in health and metabolic diseases, https://www.sciencedirect.com/science/article/pii/S2213422014000705
- Lack of Exercise is a Major Cause of Chronic Diseases, https://pubmed.ncbi.nlm.nih.gov/23798298/