You might work out mostly to improve your body composition, but exercise is good medicine. Preliminary research shows that being physically active lowers the risk of a number of health problems. Now, a new study further highlights the role exercise plays in long-term health. In fact, this study identified five chronic health problems that physical activity lowers the risk of. It also offers some idea of how much exercise you need each week to stay healthy.
How the Study Was Carried Out
For this latest study, researchers in Australia and the United States pooled the results of 174 research studies on exercise and the risk of chronic disease. These studies were published between 1980 and 2016. This body of research specifically looked at how physical activity impacts the risk of five common, chronic health problems – diabetes, ischemic heart disease, ischemic stroke, colon cancer, and breast cancer. These are some of the most common health problems that shorten our lives.
What they found was accumulating 3000 to 4000 MET minutes of physical activity per week was linked with a lower risk of these diseases. MET stands for metabolic equivalent tasks and is a measure of the energy cost of a particular activity. One MET is the quantity of energy you expend while sitting in a chair. The energy cost of all other activities is measured in relation to this. For example, an activity that expends 6 times as much energy would have a MET of 6.
So, what is a MET-minute? A MET-minute adds time to the equation. If you carried out an activity with a MET value of 6 for 30 minutes, it would be the equivalent of 180 MET minutes. (6 MET X 30 minutes). If you did this activity every day of the week, you’d have MET-minute value for the week of 180 MET minutes X 7 days = 1260 MET-minutes for the week. Here are some MET values for common activities:
· Gardening MET = 4
· Walking briskly MET = 5
· Moving heavy furniture MET = 6
· Vigorous weight training MET = 6
· Running or HIIT training MET =10 -12
You accumulate MET minutes each day by the activities (structured or unstructured) you do. In this study, the risk of developing these five common diseases dropped with each additional MET-minute of physical activity each week. Risk reduction began at 600 MET-minutes, before leveling off at around 3000 to 4000 MET minutes. Beyond 4000 MET-minutes, further risk reductions were less.
Is More Exercise Better?
Unfortunately, for those who are reluctant to exercise, the degree of physical activity you need to achieve the highest level of protection, 3000 to 4000 MET-minutes, is several-fold greater than the quantity of exercise the World Health Organization recommends. The World Health Organization currently sets the minimum at 600 MET-minutes per week.
Based on this study, exercising at this level weekly offers SOME reduction in risk, but you can lower the odds further by pushing your activity level closer to 3000 MET minutes on a weekly basis. Once you go above 4000 MET-minutes per week, the risk reduction is minimal. So, there seems to be a ceiling beyond which more exercise doesn’t dramatically lower your risk of these health problems further.
Here’s an example. If your physical activity level is around 600 MET-minutes per week, your risk for type 2 diabetes would fall only 2%. Boost your activity level to 3600 MET minutes weekly and you would enjoy an additional 19% reduction in the risk of developing type 2 diabetes. Likewise, with at least 3000 MET minutes of physical activity per week, your risk of colon and breast cancer would drop by almost 25%. That’s significant!
This data suggests that the activity recommendations made by the World Health Organization are on the low side, at least in terms of maximizing protection against these five common, chronic health problems. Yet, there is a ceiling, weekly physical activity beyond 4000 MET-minutes per week will only modestly reduce your risk further.
How Does Exercise Lower the Risk of Chronic Health Problems?
One way physical activity reduces the risk of health problems, like heart disease, type 2 diabetes, and stroke, is its impact on body weight and visceral body fat. People who are physically active tend to accumulate less visceral body fat, deep belly fat that’s strongly linked with heart disease and type 2 diabetes. Exercise also improves insulin sensitivity and prevents the metabolic problems that plague so many people. Insulin resistance is strongly associated with heart disease, diabetes, and high blood pressure.
What about cancer? Exercise reduces the amount of estrogen that your breasts are exposed to. This may be why physically active women have a lower risk of getting breast cancer after menopause. For other forms of cancer, like colon cancer, the fact that people who exercise have a healthier body weight may play a role. Inflammation is a driving force behind many health problems, including some forms of cancer. Body fat produces compounds that promote inflammation. Plus, exercise itself has anti-inflammatory benefits. The fact that exercise improves insulin sensitivity and helps lower circulating insulin is likely also a factor. Insulin and its close cousin, IGF-1, can fuel the growth of malignant cells.
Although this study focused on breast and colon cancer, a study published in the Journal of the American Medical Association earlier this year, showed a link between exercise and a lower risk of 13 types of cancer, including cancer of the esophagus, lungs, uterus, stomach, liver, kidneys, as well as the blood cancer myeloid leukemia. In addition, physical activity was also linked with a reduced risk of cancers of the rectum, colon, bladder, breasts, head, neck, and a type of immune system cancer called multiple myeloma. As you can see, exercise lowers the risk of MOST forms of cancer.
The Bottom Line
Of course, you already knew exercise is good for your health. It also calls into question whether the amount of exercise the World Health Organization recommends, 150 minutes of moderate-intensity exercise or 75 minutes of vigorous activity, is really enough. It is but only if you’re highly active when you aren’t working out.
It seems that up to a point, more movement is better for your health and that people doing no more than the World Health Organization recommends may not be getting the most protection possible against chronic disease. Still, if you work out most days of the week at a moderate to high intensity and don’t spend the rest of the day sitting, you’re doing more than the minimum. So, keep it up!
References:
Eurekalert.org. “Higher Weekly Activity Levels Linked to Lower Risk of 5 Chronic Diseases”
BMJ 2016;354:i3857 “Physical activity and risk of breast cancer, colon cancer, diabetes, ischemic heart disease, and ischemic stroke events: a systematic review and dose-response meta-analysis for the Global Burden of Disease Study 2013”
JAMA Intern Med. Published online May 16, 2016. doi:10.1001/jamainternmed.2016.1548.
NHS Choices. “Physical Activity Guidelines for Adults”
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