The Lucky Years: How to Thrive in the Brave New World of Health (29 page)

Note that physical activity encompasses a lot of different kinds of movement. It’s not just about formal exercise in a gym or going on a run. Physical activity includes, as put by the WHO, “leisure time physical activity (e.g., walking, dancing, gardening, hiking, swimming), transportation (e.g., walking or cycling), occupational (i.e., work), household chores, play, games, sports or planned exercise, in the context of daily, family, and community activities.”

The science of exercise wasn’t a course offered when I was in medical school. The world has changed immensely since then, and today entire new disciplines of medicine have emerged to study physiology in this regard. Metabolomics, for example, is a form of health profiling that identifies metabolic patterns in people that either heighten or lower their risk for certain illnesses. Scientists can get a chemical snapshot of the effects of exercise by examining blood samples. This kind of research has led to the discovery that the fitter you are, the more your body and its myriad systems benefit, thanks to dramatic changes that happen spontaneously during physical movement.

I marvel at the fact that we’ve only recently realized, from a scientific standpoint, the power of movement over time. In 2012, it was finally shown just how many years of life can be gained after age forty as a
result of various levels of physical activity, both overall and according to body mass index (BMI).
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The conclusions emerged from six studies in the National Cancer Institute Cohort Consortium, comprising 654,827 individuals from twenty-one years of age all the way up to ninety. The following graph reveals the research’s findings:

Leisure-time physical activity is associated with longer life expectancy, even at relatively low levels of activity and regardless of body weight.

Metabolic equivalent hours per week (MET-h/wk) is how the researchers calculated the extent of the participants’ exercise. A physical activity level of 0.1 to 3.74 MET-h/wk, for instance, is the same as brisk walking for up to 75 minutes per week. Higher levels of physical activity were associated with greater gains in life expectancy, with a gain of 4.5 years at the highest level (22.5+ MET-h/wk, equivalent to brisk walking for 450+ minutes per week, which is 7
¹
/
₂
hours). Substantial gains were also recorded in each BMI group. In joint analyses, being active (7.5+ MET-h/wk) and normal weight (BMI 18.5–24.9) was correlated with a gain of 7.2 years of life compared to being inactive (0 MET-h/wk) and obese (BMI 35.0+). A BMI of 35+ in an inactive individual was actually shown to be associated with seven years of life lost compared to meeting recommended activity levels and being normal weight.

So it’s a foregone conclusion: a physically active lifestyle is vital for
good health as well as important for increasing life expectancy. What probably surprised some of the researchers is that the people who were overweight (but not obese) and engaged in physical activity lived longer than those of normal weight who were inactive. Other research has also shown this to be true: it’s better to be physically fit and overweight than to be of normal weight and sedentary. Indeed, movement matters. Movement over time matters most.

While it’s common knowledge and well established now that physical fitness levels are related to risk for metabolic and cardiovascular diseases, we didn’t know about the link between fitness and cancer risk until relatively recently. The American Institute for Cancer Research now links physical activity with a reduced risk for most forms of cancer. Extended sitting periods in particular are associated with increased risk of both breast and colon cancers.

According to a study published in 2015, men with a high fitness level in midlife appear to be at lower risk for lung, colorectal, and prostate cancer, and that higher fitness level also may put them at lower risk of death if they are diagnosed with cancer when they are older.
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The explanation for the relationship between exercise and lower risk for cancer is based on the fact that physical activity does things to the body that prevent cancer from starting or progressing. It helps control energy levels and weight, balance the body’s hormonal system, regulate insulin, reduce inflammation, and influence the immune system positively. Moreover, because exercise gets your circulation going at a faster clip, there’s less likelihood for toxic substances to accumulate and trigger adverse cellular reactions.

In another related study, also published in 2015, researchers showed how influential exercise can be when someone is undergoing chemotherapy for cancer.
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Perhaps nothing can be more frustrating for doctors like me than trying to treat a cancer that continues to become increasingly stealthier, evading the drugs we throw at it. Cancers grow resistant
to treatment in many ways, one of which is by generating a network of blood vessels that become so entangled that they suffocate the tumor, depriving it of oxygen. And an oxygen-starved tumor then gains a kind of shield that protects it from chemotherapy drugs and radiation, which are designed to seek out well-oxygenated tissue. In research circles, we’ve long tested various approaches to improving blood flow to tumors in the hopes of improving treatments. Nothing has worked well, until researchers led by Duke Cancer Institute (DCI) studied the effects of exercise in mice made to model breast cancer cases in humans. They found that physical activity stimulated significant improvements in the number and function of blood vessels surrounding tumors, boosting oxygen flow to the cancer site. When blasted with chemotherapy, the tumors shrank much better in these exercising animals than they did in sedentary ones. The scientists employed two different models of breast cancer cells, implanting them in mice and then making some of them run on a wheel while allowing others to remain sedentary.

Tumor growth was significantly slower among the animals that exercised than in the sedentary mice. The death of cancer cells was in fact 1.5 times higher in the exercisers. Mice that ran on the wheel developed small blood vessels that were about 60 percent higher in density compared to the sedentary controls’, thereby leading to improved oxygen transport and less oxygen starvation to the tumor.

Next, the researchers looked at whether exercise would improve chemotherapy. The mice were randomly assigned to one of four groups: sedentary, exercise alone, chemo alone, or exercise in combination with the chemotherapy. The rate of cancer growth was dramatically delayed in mice treated with exercise and chemo compared to all of the other groups. Cancer growth was also slowed in both the exercise alone and chemo alone groups, but there was no difference in tumor growth rate between those two groups. This observation suggested that exercise has a similar effect to chemotherapy. What exercise was doing, essentially, was changing the body’s context—changing the environment in a way that made it less hospitable for the tumor to grow.

Earlier studies have confirmed that people who are fitter during their thirties through their fifties have less chronic illness in later years. One of these studies in particular, published in the
Archives of Internal Medicine
in 2012, looked at 18,670 participants in the Cooper Center Longitudinal Study, which contained records of more than 250,000 patients over forty years.
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They compared the data with the participants’ Medicare claims during the ages of seventy to eighty-five. The results were similar in both men and women:

People who increased their fitness levels by 20 percent in their midlife years decreased their chances of developing chronic illness by 20 percent in old age. When the individuals turned fifty, the part of the group in the bottom 20 percent of the fitness scale had almost
twice
as many chronic illnesses as those in the top 20 percent. People with the highest fitness levels at midlife enjoyed more time being illness-free than those who were the least fit. Fitter people also lived their last five years with fewer chronic diseases.

Just how much time do we spend in a parked position? According to one team of researchers at Louisiana’s Pennington Biomedical Research Center who published their findings in 2012, whether or not people exercise the recommended 150 minutes a week, we spend an average of 64 hours a week sitting, 28 hours standing, and 11 hours moving and walking in ways that don’t count as exercise.
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That means that no matter how active we are otherwise, most of us are sitting for more
than nine hours a day. Although this group’s calculations were based on women, it likely reflects what’s happening with men as well. One observation made by these researchers that they didn’t expect is that the individuals who exercised the most didn’t spend less time sitting. Regular exercisers were actually prone to making less of an effort to move outside their designated workout time. Other research has shown that people are about 30 percent less active overall on days when they do set aside time for a formal workout, as opposed to the days when they don’t plan an exercise routine.

What all this translates to is a concern not only for those who don’t exercise at all, but also for people who lack general movement on a regular basis to counteract all the harm that can result from sitting for most of the day. Multiple effects happen simultaneously when the body is on the go, even if it’s just walking around while talking on the phone, taking the stairs instead of the elevator, or simply making a point to get up every hour for a five-minute stroll, stretch, or jog in place. All of these movements will have positive biological effects to offset the poison of excessive sitting. It doesn’t help that our social infrastructure accommodates idleness. We have LEED (Leadership in Energy and Environmental Design) standards for the environmental impact of buildings, so why don’t we establish “LHD” (Leadership in Health Design) standards for office buildings also? This can entail any number of innovations, such as more openly accessible staircases, in-house gyms, and nutritious food served in cafés and commissaries. We have become a society in which the more important you are, the closer your parking space is to your desk, and the more resources you have, the more bathrooms your family enjoys so no one has to walk far to use one. We need to change this thinking and develop building codes and incentives that reflect a new understanding of health.

Don’t let appearances skew your perception of fitness. There are a lot of people today who embody the so-called lean paradox, which refers to the way thin people can look healthy on the outside but be suffering from many health problems on the inside. These individuals may try to manage their weight and health through diet alone, shunning physical activity.
They lose out on exercise’s metabolic benefits, and they experience consequences similar to those they would if they were morbidly obese.

Strength training becomes more important the older we get, as we naturally lose muscle mass and strength. Strength typically peaks between thirty-five and forty years of age. After that, we start losing about 1 percent of our strength per year. That rate picks up speed in our seventies and eighties. Strength training supports muscle mass, can help rebuild it, and can help increase bone mass. The muscles we employ when we lift a weight put pressure on our bones, forcing them to get stronger. Muscle mass and strength are among the most underappreciated and unrecognized aspects of health.

Muscle plays key roles in the body beyond the obvious ones like helping us stand erect and move; just as fat stores extra calories for energy reserves, muscle serves as an emergency supply of the amino acids we need to build tissues and biological substances. The body doesn’t store amino acids as it does fat and carbs; if there’s not enough coming in from the diet, the body will take them from its own tissue by breaking down its protein sources, usually muscle. Which is partly why loss of muscle can lead to loss of life.