How Much Exercise Do You Need To SuperPower Your Health?
HHN: In "What Every Adult Needs To Know About Exercising for Health," you reported that most people can reduce their risk of getting heart disease, diabetes, and some cancers by 25% - 50% and live two years longer by doing moderate aerobic exercise for 150 minutes every week. Is that the optimal exercise Rx for our health?
CG: On average, the optimal exercise Rx appears to be about twice that number—300 minutes weekly of moderate aerobic exercise (exercise that feels «fairly light to somewhat hard," or 64% - 76% of maximum heart rate. Here’s how to calculate your exercise and reach your minutes.) People who do cardio/endurance exercise each week for 5 hours or slightly more realize these 3 health benefits:
- Weight Loss: The most successful dieting—both in losing weight and keeping that weight off—according to most studies;
- Healthier Body Composition, especially a trimmed abdominal area and reduced body fat, which leads to
- Better Health-Related Biomarkers: improvements in blood lipids (especially triglycerides), high density lipoproteins (the "good cholesterol"), glucose, and insulin levels, seen in many studies.
HHN: How do exercise-induced changes in weight, body composition, and biomarkers translate into better health?
CG: A few examples:
One 2015 study compared two large groups of Americans aged 65+: those who performed 300+ minutes of light-intensity activity weekly and their less active contemporaries. Overall, the 300+ group had a lower body mass index, a lower waist circumference, and these favorable biomarkers:
- Lower C-reactive protein (measuring bodily inflammation; high values increase risk of cardiovascular events);
- Lower systolic blood pressure (reducing heart attack risk); and
- Lower insulin resistance (decreasing risk of diabetes and heart disease)
The 300+ minute group also had fewer chronic diseases, and the researchers estimated they were 18% less likely to get a chronic disease.
Another 2015 study, published in JAMA Oncology, compared two groups of previously inactive postmenopausal women."About 300 minutes of aerobic exercise may lower postmenopausal women’s risk of breast cancer."Approximately half of these 400 women exercised for 150 minutes/week; the other group exercised 300+ minutes weekly. After a year, the 300-minute group had a significant reduction in total body fat in comparison to the 150-minute group. Since a larger body of research shows that body fat increases postmenopausal breast cancer risk, the researchers hypothesized that 300-minutes of aerobic exercise may lower postmenopausal women’s risk of breast cancer.
In other findings, exercising 300+ minutes weekly lowered some people’s cholesterol sufficiently to decrease their dosage of cholesterol-lowering statin drugs, and exercising in addition to taking statins appears more effective in reducing heart risk than statin use alone Also, some people with diabetes have normalized just from the exercise!
In essence, cancer, diabetes, and heart diseases have some of the same underlying correlates, including a sedentary lifestyle and"Cancer, diabetes, and heart diseases have some of the same underlying correlates."excess body fat, which increases cytokines and other inflammatory substances in the body. Exercise reduces body fat, abdominal adiposity, and inflammation. It also boosts the immune system, which helps in cancer prevention; immune factors relating to different types of cancer are increasingly being uncovered.
Getting 300 minutes of exercise weekly seems to achieve all this most successfully.
More Exercise = Better Health?
HHN: In some of these studies, participants exercised for 300 minutes or more. Might the exercise level for optimal health exceed 300 minutes?
CG: We don’t know the exact physical activity level for optimal health.
Most research indicates that the biomarker changes we’ve been discussing are exercise dose-responsive, up until 300 minutes or so. In other words, on average, a person’s biomarkers continue to improve as his/her physical activity increases, up to about 300 minutes/weekly or a little more. At some point the biomarkers appear to level off and/or show diminishing returns.
HHN: In this 2015 study, which pooled 12 studies including approximately 370,000 adults for about 13 years, researchers reported: "People who did 2 to 4 times more exercise than the U.S. minimum activity recommendations lowered their risk of heart failure by 20 percent and 35 percent" respectively. Simplifying, this translates somewhat to 300 minutes of weekly exercise reducing heart failure risk by 20%, and 600 minutes reducing risk by 35%, thereby offering another 15% protection. Should the ACSM consider revising its minimum exercise guidelines, as the study authors suggest? And for optimal exercise, should 600 minutes be the new 300?
CG: I do not think so at this time. The data to support this is too limited.
This very interesting study supports the dose responsiveness of exercise: physical activity reaching the target volumes reduces risk"A new study shows high-volume exercise reduces heart failure; other studies indicate it results in heart damage. We need further study to sort out the discrepancies."of developing heart failure, and more exercise can provide even greater benefits. However, this study also suggests that volumes much greater than recommended are beneficial in reducing heart failure, while other studies suggest that physical activity at this level may provide diminishing returns and may even cause harm—markers of heart damage as well as increased symptoms of depression and anxiety.
ACSM is always reviewing new relevant research that can further inform its activity recommendations. But it is premature to revise based upon the results of one study—even a meta analysis—because:
- All research findings need to be replicated.
- The discrepancy between this and other studies showing that additional exercise can result in heart damage needs further study in a variety of populations.
- We still have a plethora of studies supporting the standard exercise target of 150 minutes per week.
- Finally, given the large number of people who fail to get even 150 minutes of physical activity weekly, we might be setting a target that is not attainable by most—and in fact may provide a barrier because it may seem overwhelming.
HHN: Do you believe there is an upper limit of exertion for optimal health?
CG: Most scientists would likely say there is a level of exercise that could be harmful for a given individual, especially for those who never take a day off.
HHN: I was struck by the latest 2015 Copenhagen Heart Study, comparing about 1,100 healthy joggers to some 4,000 healthy non-joggers, in which the researchers pointed to "a U-shaped association between all-cause mortality and dose of jogging as calibrated by pace, quantity, and frequency of jogging. Light and moderate joggers have lower mortality than sedentary nonjoggers, whereas strenuous joggers have a mortality rate not statistically different from that of the sedentary group."
CG: This study is intriguing, and also worrisome at first look. However, when one looks at the paper more carefully, the number of adverse events was quite small, so the conclusions are somewhat overstated.
Other studies, such as Potential Adverse Cardiovascular Effects From Excessive Endurance Exercise, suggest there can be adverse effects of large amounts of exercise. But again, these results are quite tentative.
It is unknown how much exercise is too much—and it’s likely different for different people."How much exercise is too much is likely different for different people."Exercise is very individualized—how it affects you depends on many factors, including your overall lifestyle, starting weight, diet, and genetics. Some marathon winners, for example, can run a race one week and then another the following week, with seemingly no adverse impact. Certain people in the middle or the end of the marathon pack, however, may have heart issues. Research suggests that some of them have inflammation of the heart muscle.
Advice for Endurance Athletes
HHN: Can endurance athletes get tested to find out whether they have an increased heart disease risk?
CG: Most of the data suggests that an EKG, echocardiogram, or stress test does not help identify these individuals, unless they have symptoms or signs of heart disease. But athletes can take other steps to protect themselves.
First, remember: Athletes are not invincible, no matter how much you or I do and how great we may feel. We need to visit our doctor and test for the risk factors that can be measured.
Second, don’t ignore the signs of a potential problem. Athletes, myself included, are used to pushing through discomfort. It comes with our macho view— and that’s a male and female macho: that we’re tough and can just keep going.
That’s why it’s especially important to pay attention to unusual symptoms. If you’re feeling atypically dizzy, extremely tired, or unwell, or you’re having discomfort pretty much anywhere above the navel, have a conversation with your doctor to find out whether or not something’s going on.
Athletes & Arthritis
HHN: Is it true that endurance athletes have an increased risk of arthritis later in life?
CG: It’s not a direct cause and effect of a particular physical activity. For example, it’s a myth—there's no data supporting the notion—that runners get more arthritis than non-runners.
That said, people who repeatedly do the same activity, especially over long distance or duration, are more likely to get overuse injuries. And injuries, such as tendonitis, may contribute to improper joint function, and then lead to arthritis. In this way, runners who’ve had overuse injuries are at risk.
Sports such as football, rugby, and basketball are more likely to result in arthritis, because they involve a lot of twisting and put extra tension on the joints. Again, it’s the joint injury from overuse, not the exercise itself, that’s the culprit.
To reduce arthritis risk, your best option is to engage in a mixture of physical activities. People who run and swim, or run and cycle, for example, seem to have fewer injuries than those who participate only in one sport.
Your Optimal Health
HHN: Is there anything else you’d like to say to active readers about exerciseing for optimal health?
CG: Yes. First, try to vary your exercise. You’ll work diverse muscles and get different health benefits. It’s the most effective way to get the maximum bang for your time.
Second, know yourself. If you’re not already active, or have little desire to take your exercise to the next level, don’t focus on getting to 300 minutes. You’ll have the most health benefits from doing the amount of physical activity you enjoy and can comfortably sustain.
On the other hand, if you really like being active, don’t limit yourself to 150 minutes. If you can do 300, great!
In short, the best Rx for you is the one you truly enjoy and can habituate.by