From The Desk Of Clarence Bass
“No single medication treatment can influence as many organ systems in a
positive way as can physical activity.”
Exercise Adds Years—Exploring the Limits
(Professor Speaks Out Below)
Exercise is the best medicine for just about everything that ails us—including early death. We are learning more and more about how and how much.
Numerous studies have shown that exercise reduces the risk of many chronic diseases and increases longevity. Two minutes of moderate exercise is said to be roughly equivalent to one minute of vigorous exercise. Put another way, total energy expenditure is the key factor. Breaking with the party line, researchers from James Cook University and other universities in Australia questioned the assumption that intensity simply burns calories faster. They predicted that a higher proportion of vigorous activity would produce a lower risk of early death. And that’s what they found.
“Independent of energy expenditure, vigorous physical activity is more efficient than moderate activity in inducing cardiorespiratory and metabolic fitness, which is a stronger predictor of morbidity and mortality than activity,” Gebel, Ding, Chey, et al wrote in introducing their study. (JAMA Internal Medicine, online April 6, 2015) “Therefore, it could be hypothesized that there might be greater health benefits from vigorous activity than from moderate activity alone, even when the overall amount of activity is held constant.” Using that rationale, they predicted that vigorous activity would eclipse total energy expenditure in extending lifespan.
Again, they found that more intensity meant reduced all-cause mortality, independent of the total time spent being active. “[Moreover], this finding applied to both sexes, all age categories, people with different weight status, and people with or without cardiometabolic disease,” they reported.
The size of the study was one of its strengths; the type was another. The Aussie scientists began by asking more than 200,000 people between 45 and 75 years of age how much of their current activity was vigorous—anything that “made you breathe harder or puff and pant”—and how much was moderate—walking, gentle swimming, social tennis, gardening or housework and the like.
Asking about activity level—volume and intensity in this case—beforehand has been found more accurate than asking participants to recall what they did in the past. Asking beforehand is the only practical way to assess the effect of exercise intensity on death rates. It is not feasible to carry out a randomized controlled trial. You simply can’t get people to agree to follow a specific exercise pattern over a long period of time. This study is about the best there is likely to be for assessing the effect of behavior over a long period of time.
During the 6.5 year follow up period, 7435 of the 217,755 participants died.
Participants were divided into three groups based on the proportion of vigorous activity in their total activity mix. The percentage of deaths in each category declined in linear fashion based on the proportion of vigorous activity. The most deaths were in those who did no vigorous activity, followed by those with vigorous activity less than 30% of total activity, and finally those doing more than 30% vigorous activity.
Those reporting less than 30 percent vigorous activity had a mortality rate 9% lower than those with no vigorous exercise, while those who reported doing more than 30 percent vigorous activity had a 13% reduction in mortality. In short, more than 30% vigorous activity reduced deaths by almost 50% compared to less than 30% vigorous activity.
“Among people reporting any activity, there was an inverse dose-response relationship between proportion of vigorous activity and mortality,” the researchers concluded. “Our findings suggest that vigorous activities should be endorsed in clinical and public health guidelines to maximize the population benefits of physical activity.” (Klaus Gebel et al, JAMA Internal Medicine, online April 6, 2015)
The explanation offered by Dr. Gebel and colleagues is straight forward, about as clear as physiology speak gets:
A potential explanation for the positive effect of engaging in some vigorous activity on longevity might be that high-intensity activities lead to more physiologic adaptations, which improve function and capacity. For example, regular aerobic activities increase cardiac stroke volume and capillary density, improve endothelial function, and reduce peripheral resistance, all of which improve the delivery of oxygen and glucose to tissues. Some clinical trials with equal amounts of physical activity have found that participants exposed to higher- rather than lower-intensity activity had more improvements in maximum oxygen consumption, blood pressure, or lipid profiles. Similarly, a clinical trial found that, independent of energy expenditure, high-intensity training was more efficient in achieving anti-inflammatory effects in patients with type 2 diabetes and metabolic syndrome.”
Clearly, intensity matters and matters a lot. Continually challenging the body improves function in just about every way.
Dr. Gebel does suggest that people who do not exercise regularly—or have health problems—should talk to their doctor before embarking on a vigorous exercise program. Encouragingly, he adds that interval training with short bursts of vigorous effort is often preferred by older people, including those who are overweight or obese. Approached properly, vigorous exercise is more interesting, more satisfying—and more result producing.
Intensity Comes in Many Forms
Photo by Wayne Gallasch
Second Study Reports Peak Longevity Benefits
As I was putting the final touches on this article, I learned of in an even larger study reporting exciting new details on exercise and longevity; the study is in the same issue of JAMA Internal Medicine. Researchers from the National Cancer Institute, Harvard, and other institutions reported impressive new findings on the upper limit of longevity benefit and probed the point of possible harm.
Hannah Arem, MHS, PhD, (National Cancer Institute) and colleagues combined activity data from six large studies involving a total of 661,137 mostly middle aged men and women from the United States and Europe. They observed 116,686 deaths over 14.2 years of follow-up.
Current activity guidelines for Americans recommend a minimum of 1.25 vigorous-intensity or 2.5 moderate-intensity hours per week of aerobic activity, and suggest additional health benefits by doing more than double that amount.
Arem et al found that three to five times the recommended minimum amount of exercise added significantly to lifespan. Ten or more times the minimum, however, added no additional benefit—or excess risk.
The trajectory of reduced mortality risk looked like a playground slide with a long essentially flat area at the bottom. Compared to individuals reporting no leisure time physical activity, they found a 20% lower risk of death among those doing less than the recommended limit, a 31% lower risk at 1 or 2 times the recommended minimum (2.5 to 5 hours/wk), 37% lower at 2 to 3 times (5 to 7.5 hours/wk), and “an upper threshold for mortality benefit” of 39% at 3 to 5 times the recommended minimum (7.5 to 12.5 hours). No additional benefit—or evidence of harm—was found at 10 or more times the recommended minimum.
A similar benefit curve was found for mortality due to heart disease and to cancer.
In summary, maximum longevity benefit came at a little over an hour a day of moderate activity (420-700 minutes) such as walking—or about half that amount (135-240 minutes) of vigorous activity such as 2.25 hours a week of running at 10-min mile pace. Doing substantially more is safe but provided no added health benefit.
As in the Australian study, benefit was consistent in men and women, different age groups, various lifestyle factors, and individuals with and without cardiovascular disease and cancer.
A strength of the study was that pooling results from six large studies—and the long follow up—provided ample information on individuals reporting such high levels of exercise. This is a big plus because there aren’t many older individuals who do such high levels of activity or vigorous exercise.
“In regard to mortality, health care professionals should encourage inactive adults to perform leisure time physical activity and do not need to discourage adults who already participate [at] high-activity levels,” the researchers concluded.
The two studies taken together strongly suggest that exercise volume and intensity both contribute significantly to longevity. Unfortunately, studies aimed at the general public tend to assume that most people will reject any form of exercise which causes discomfort. As a consequences, the Aussie study described vigorous exercise as anything that makes you breathe harder and the other study used running at 10-minute mile pace as an illustration. Laszlo Bencze, who alerted me to the Australian study, observed that what the researchers called “vigorous” would be called fairly mild by many of us. That makes one wonder whether more vigorous exercise would produce more longevity benefits.
Perhaps harder-but-less exercise would be better for the well trained—and willing—person. Brief high-intensity exercise stimulates just about every organ system in the body—and extended low-intensity exercise promotes repair and growth. Those are the two forms of exercise I do. I call it a barbell strategy: high-intensity on one end and low-intensity on the other, with very little in between. Challenge. Rest. Improve. See my “Diet and Training Philosophy, in Brief” http://www.cbass.com/PHILOSOP.HTM
Muscles energize the metabolism; they “speak” to every organ in the body
Photo by Wayne Gallasch
You’ll note the weight training, which went unmentioned in both studies, is a very important part of my training regimen. Research and experience tell me that including strength training would add significantly to longevity benefits. University of Miami Professor Joseph Signorile explains why in his landmark book “Bending the Aging Curve.”
“As we age, the motor units that we lose are mainly the fast-twitch variety,” Signorile writes. “The slow-twitch fibers show practically no change.”
A picture is worth a thousand words. Signorile uses a graph to show the pattern of change in fast and slow twitch muscle fibers as we age. The curve of the slow-twitch fibers over time is no curve at all; it’s flat, showing essentially the same number of slow fibers at 60 and 90. On the other hand, the fast-fiber curve drops rapidly from 60 to 90.
In short, the loss of muscle size with age is virtually all due to shrinkage and death of fast-twitch fibers. Translated to the activities of everyday life, this means the untrained person becomes slower and weaker with age. Independence suffers substantially over time.
It’s a dismal picture, but all is not lost. Far from it. We can keep our fast-twitch fibers alive and well with resistance training. Signorile is a big booster of resistance training. For more details, see my commentary on Bending the Aging Curve: http://www.cbass.com/BendingTheAgingCurve.htm
Taking it a step further, muscle mass may be the single most important factor in health and longevity. In their breakthrough book “Biomarkers,” Tufts University Professors Evans and Rosenberg stated that the first biomarker, muscle mass, is responsible for the vitality of your whole physiological apparatus. Muscle mass and strength, the second signpost, are our primary biomarkers. They’re the lead dominoes, so to speak. When they start to topple, the other biomarkers soon follow. On the other hand, when muscle mass and strength are maintained, the other indicia of aging are likewise maintained.
That is where strength training comes to our aid. Aerobic exercise and diet are important, but strength training, according to the authors, is pivotal if you want to stay young longer. For more details, see my commentary on Biomarkers: http://www.cbass.com/Biomarkers.htm
Finally, see my article “Muscle Talk” for more about the metabolic benefits of high intensity exercise: http://www.cbass.com/MuscleTalk.htm
I believe we are just beginning to explore the best possible forms of exercise for health and longevity.
Understandably, most physicians and health care professionals are primarily interested in persuading their patients to do any form of exercise on a regular basis. They don’t have much time for those who are interested in exploring the outer limits of what’s possible.
It’s refreshing and inspiring to reflect on the awesome power we have to extend our lifespan and make every day more productive and satisfying.
There are of course limits. Let’s find out what they are.
As always, check with your health care provider before making major changes in your lifestyle.
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Professor Speaks Out on Exercise
Great article! In
particular, your discussion regarding the difference between public
recommendations and what might be optimum for a healthy individual are pertinent
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