Posts Tagged "Exercise"

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You may want to stand up to read this.

A new study suggests that people who spend the bulk of their day sitting — whether behind the wheel, in front of the TV or working at a computer — appear to have an increased risk for certain kinds of cancers.

Previous studies have tied too much time spent sedentary to a variety of health problems, including heart disease, blood clots, a large waistline, higher blood sugar and insulin, generally poor physical functioning, and even early death.

For the new study, researchers zeroed in on 43 studies that specifically looked at the link between sitting and nearly 70,000 cases of cancer.

After combining the results from individual studies — a statistical tool that helps to reveal trends in research — there was good news and bad news.

The good news? Being sedentary did not appear to be linked to every kind of cancer. Scientists found no relationship between sitting and breast, ovarian, testicular or prostate cancers, or cancers of the stomach, esophagus and kidneys, or non-Hodgkin lymphoma.

The bad news was that there did seem to be a consistent relationship between hours spent sitting and an increased risk for colon and endometrial cancers.

People who spent the most time sitting during the day had a 24 percent increased risk of getting colon cancer compared to those who logged the least number of hours in a chair, according to the study.

When the researchers looked just at time spent watching TV, the risk jumped even more. Those who clocked the most hours glued to the tube had a 54 percent increased risk of colon cancer compared to those who watched the least.

That may be because viewers tend to consume unhealthy snacks and drinks while watching TV, said study author Daniela Schmid, an epidemiologist at the University of Regensburg in Germany.

For endometrial — or uterine — cancer, the risks were even higher. There was a 32 percent increased risk for women who spent the most time seated compared to those who sat the least, and a 66 percent increased risk for those who watched the most TV, the study authors said.

Moreover, every two-hour increase in sitting time was linked to an 8 percent increased risk of colon cancer and a 10 percent increased risk of endometrial cancer.

The risks remained even for “active couch potatoes” — folks who squeeze in some time at the gym but still spend most of their day off their feet. This suggests that regular exercise can’t offset the risks of too much sitting, the study authors said.

The findings, published June 16 in the Journal of the National Cancer Institute, make sense to Dr. Graham Colditz. He’s the associate director for prevention and control at Washington University’s Siteman Cancer Center in St. Louis.

“High blood sugar and high insulin is a clear sort of pathway to colon cancer, and we know from intervention studies that walking lowers insulin and getting up after meals lowers blood sugar compared to sitting,” said Colditz, who was not involved in the research.

As for endometrial cancer, “Obesity is a phenomenally strong cause. In fact, it is the main modifiable risk factor for endometrial cancer,” he said.

“So for me, the likely scenario there is that the sitting, the weight gain and obesity really go together and exacerbate the risk of endometrial cancer,” he added.

Because the studies included in the review only looked at broad relationships, they can’t prove that sitting, by itself, causes cancer. But the findings appeared to be remarkably consistent across studies, so Colditz thinks they should be taken seriously.

The study authors agree.

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“Cutting down on TV viewing and sedentary time is just as important as becoming more active,” said Schmid. “For those whose jobs require them to sit at a desk most of the day, we recommend breaking up the time spent sitting by incorporating short bouts of light activity into the daily routine,” she added.

Source: Web MD

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It’s possible that some of us are born not to run. According to an eye-opening new genetics study of lab rats, published in The Journal of Physiology, the motivation to exercise — or not — may be at least partly inherited.

For years, scientists have been bedeviled by the question of why so few people regularly exercise when we know that we should. There are obvious reasons, including poor health and jammed schedules. But researchers have begun to speculate that genetics might also play a role, as some recent experiments suggest. In one, published last year, sets of fraternal and identical adult twins wore activity monitors to track their movements. The results indicated that the twins were more alike in their exercise habits than a shared upbringing alone would explain. Their willingness to work out or sit all day depended to a large extent on genetics, the researchers concluded.

But which genes might be involved and how any differences in the activity of those genes might play out inside the body were mysteries. So scientists at the University of Missouri recently decided to delve into those issues by creating their own avid- or anti-exercising animals.

They accomplished this task by inter-breeding normal rats that had voluntarily run on wheels in the lab. The male rats that had run the most were bred with the female rats that also had run the most; those that had run the least were likewise mated. This scheme continued through many generations, until the scientists had two distinct groups of rats, some of which would willingly spend hours on running wheels, while the others would skitter on them only briefly, if at all.

In their first experiments with these rats, the researchers found some intriguing differences in the activity of certain genes in their brains. In normal circumstances, these genes create proteins that tell young cells to grow up and join the working world. But if the genes don’t function normally, the cells don’t receive the necessary chemical messages and remain in a prolonged, feckless cellular adolescence. Such immature cells cannot join the neural network and don’t contribute to healthy brain function.

In general, these genes worked normally in the brains of the rats bred to run. But their expression was quite different in the non-runners’ brains, particularly in a portion of the brain called the nucleus accumbens, which is involved in reward processing. In humans and many animals, the nucleus accumbens lights up when we engage in activities that we enjoy and seek out.

Presumably as a result, when the scientists closely examined the brains of the two types of rats, they found that by young adulthood the animals bred to run had more mature neurons in the nucleus accumbus than did the non-runners, even if neither group had actually done much running. In practical terms, that finding would seem to indicate that the brains of pups born to the running line are innately primed to find running rewarding; all those mature neurons in the reward center of the brain could be expected to fire robustly in response to exercise.

Conversely, the rats from the reluctant-running line, with their skimpier complement of mature neurons, would presumably have a weaker innate motivation to move.

Those results would be disheartening, except that in the final portion of the experiment the scientists had reluctant runners exercise by setting them on running wheels, while also providing some born-to-run animals with wheels. After six days, the unwilling runners had accumulated far less mileage, about 3.5 kilometers (two miles) per rat, compared to almost 34 kilometers each by the enthusiasts.

But the halfhearted runners’ brains were changing. Compared to others in their family line that had remained sedentary, they now showed more mature neurons in their nucleus accumbens. That part of their brain remained less well developed than among the naturally avid rat runners, but they were responding to exercise in ways that would seem likely to make it more rewarding.

What, if anything, these findings mean for people is “impossible to know at this point,” said Frank Booth, a professor of biomedical sciences at the University of Missouri who oversaw the study. Rat brains are not human brains, and rat motivations are at best opaque.

Even so, Dr. Booth said, his group’s data would seem to suggest “that humans may have genes for motivation to exercise and other genes for motivation to sit on the couch,” and over generations, one set of these genes could begin to predominate within a family. But predispositions are never dictatorial.

“People can decide to exercise,” whatever their inheritance, Dr. Booth said, and, as his study’s final experiment suggests, they could rewire their brains so that moving becomes a pleasure.

Source: New York Times

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As a 10-mile-a-day runner, Dave McGillivray thought he could eat whatever he wanted without worrying about his heart. “I figured if the furnace was hot enough, it would burn everything,” said McGillivray, who is 59.

But a diagnosis six months ago of coronary artery disease shocked McGillivray, a finisher of 130 marathons and several Ironman-distance triathlons. Suddenly he regretted including a chocolate-chip-cookie recipe in his memoir about endurance athletics.

“My first reaction was, I was embarrassed,” he said.

As race director of the Boston Marathon, McGillivray is a high-profile exhibit in a growing medical case against the devil-may-care diets of many marathoners. Their high-mileage habit tends to lower their weight, blood pressure, heart rate and cholesterol levels, leading them (and sometimes their doctors) to assume their cardiac health is robust regardless of diet.

“‘I will run it off’—that attitude clearly prevails among the marathoners themselves, almost sometimes to an arrogance,” said Paul Thompson, a veteran marathoner who is chief of cardiology at Hartford Hospital.

A growing body of research shows the error of that thinking. A study published in the current edition of Missouri Medicine found that 50 men who had run at least one marathon a year for 25 years had higher levels of coronary-artery plaque than a control group of sedentary men. A British Medical Journal study published this year compared the carotid arteries of 42 Boston Marathon qualifiers with their much-less active spouses. “We hypothesized that the runners would have a more favorable atherosclerotic risk profile,” says the article. As it turned out, that hypothesis was wrong.

A small body of research suggests that heart problems may arise not in spite of extreme-endurance exercise but because of it. That has led some cardiologists to theorize that, beyond a certain point, exercise stops preventing and starts causing heart disease.

“Studies support a potential increased risk of coronary artery disease, myocardial fibrosis and sudden cardiac death in marathoners,” Peter McCullough, a Baylor University cardiologist, wrote as lead author of an editorial in the current Missouri Medicine.

But many cardiologists are skeptical. “The science establishing a causal link between vigorous exercise and coronary disease is shaky at best,” said Aaron Baggish, a Massachusetts General Hospital cardiologist who does triathlons and marathons. Even so, he said, “I’ve never once told a patient they need to run marathons or race triathlons to maximize health, as this is not accurate.”

Reports of heart disease in runners are prompting some marathoners to get coronary-artery scans. Ambrose Burfoot, winner of the 1968 Boston Marathon and editor-at-large of Runner’s World magazine, is 67 years old, 6 feet tall and only 147 pounds. A lifelong vegetarian, he subsists mostly on fruits, vegetables and nuts, though he eats “cookies and all dairy products—cheeses, ice creams etc.,” he wrote in an email.

“Last March I learned that I have a very high coronary calcium,” he said. “I have a condition perhaps similar to Dave McGillivray’s.”

The medical profession’s recommendation for such runners depends on which cardiologist they visit. James O’Keefe, a Kansas City cardiologist and ex-triathlete who believes sustained endurance exercise can damage the heart, said he would recommend no more than 20 miles a week at a modest pace.

Thompson and Baggish, however, believe that in many cases endurance athletes diagnosed with heart disease can safely continue doing marathons and triathlons, if their conditions are treated. Thompson argues that risk must be weighed against quality of life, an idea that Burfoot embraces.

“I subscribe to the old saw: ‘Exercise—it might not add years to your life, but it adds life to your years,'” said Burfoot.

But cardiologists are united in their campaign against the old notion that high-calorie workouts confer a free pass to eat anything.

Those who run several hours a day often dream about cookies and ice cream. When McGillivray ran from coast to coast in 1978, he tended to finish each day at a Dairy Queen. “It wasn’t just replacing calories but a mental thing—that vanilla shake was my reward,” he said.

Replacing thousands of calories with purely nutritious foods can be challenging. Since receiving his diagnosis last October—and radically changing his diet—the 5-foot-4 McGillivray has dropped to 128 pounds from 155, an improvement he celebrates.

Far from cutting back his workout regimen, McGillivray has amped it up, boosting his weekly mileage to 70 from about 60. As race director of the Boston Marathon, which is April 21, he plans to continue his tradition of running that course after the last runner has crossed the finish line. And to celebrate turning 60 in August, he plans to complete an Ironman-distance triathlon.

Although McGillivray says that his cardiologist, Baggish, gave him “the green light” for such challenges, Baggish said in an email that, “I do not give patients (Dave included) green or red lights. We engage in an open discussion about known and uncertain risks and benefits and come up with a collective and very individualized plan about what is reasonable.

“In Dave’s case,” he added, “we did just this and he is leaning toward doing the (Ironman) with full knowledge of the fact this his risk is elevated compared to the general field.”

Some critics say that continuing to engage in endurance athletics despite cardiac disease is evidence of addiction. “I’m not afraid to call myself an exercise addict,” said Burfoot. “I have always been afraid of dying on a run. But the way I look at it now, it’s not that running will have killed me. Running has enhanced my life immeasurably, but it could also ‘trigger’ a life-ending event that probably would have happened even sooner except for my running.”

Source: Wall Street Journal

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Regardless of how much time older Americans spend being active, those who sit for more hours each day are more likely to be disabled, according to a new study. Researchers found that every hour people 60 years old and older spent sitting daily was tied to a 46 percent increased risk of being disabled – even if they also exercised regularly.

“It was its own separate risk factor,” Dorothy Dunlop told Reuters Health. Dunlop is the study’s lead author from the Northwestern University Feinberg School of Medicine in Chicago. “We know that being active is good for your health and we know a sedentary lifestyle is bad for your health,” she said. But few studies have examined whether moderate to vigorous physical activity offsets the possible negative effects of being sedentary.

Dunlop and her colleagues write in the Journal of Physical Activity and Health that Americans already lead sedentary lifestyles. Among older Americans disability is also a major concern because it has been linked to increased medical spending and a higher risk of going into a nursing home or other care facility.

If future studies can confirm that sedentary behavior causes disability, which this study does not, then older people may possibly avoid becoming disabled by being more active throughout the day. For the new report, Dunlop and her colleagues analyzed data collected in 2003 through 2006 as part of a long-term government study of American health. The researchers used information on 2,286 adults who were 60 years old or older, had worn a device that measures physical activity for at least four days and had a physical exam. Participants were considered to have a disability if they couldn’t perform a self-care task, such as getting dressed, by themselves. Survey participants spent about 14 hours awake each day, on average. Of that, an average of nine hours was spent sitting or otherwise not moving.

After taking into account the amount of time people spent doing moderate to vigorous physical activity, their age, their health and whether they were well-off, the researchers found that each hour of daily sitting was linked to a 46 percent increased risk of having a disability. The study can’t say whether a sedentary lifestyle leads to disability or if having a disability leads to a sedentary lifestyle, however. In addition, the authors note that their records of physical activity may not take into account some forms of exercise, because the devices that participants wore may not pick up upper body movement or cycling. Participants also didn’t wear the devices while swimming.

Stephen Kritchevsky told Reuters Health it’s too early to tell if interventions that get people moving during the day will prevent disability, but they couldn’t hurt because other studies suggest activity improves functioning. He heads the Sticht Center on Aging at Wake Forest Baptist Medical Center in Winston-Salem, North Carolina and wasn’t involved in the new research. “The fact that people are physically limited in some way is even a bigger reason to try and do things, because there is plenty of research that shows that’s likely to improve function,” Kritchevsky said.

Dunlop said older adults should be as physically active as possible. They should also know that being sedentary is possibly bad for their health. “The goal here is to accumulate more light activities to replace the sitting and keep going on the moderate activity that you’re already engaged in,” she said.

SOURCE: (Reuters) Journal of Physical Activity and Health, online February 19, 2014.

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Walking, fast or slow, is wonderful exercise. But now a first-of-its-kind study shows that to get the most health benefits from walking, many of us need to pick up the pace.

The findings stem from a new analysis of the National Walkers’ Health Study, a large database of information maintained at the Lawrence Berkeley National Laboratory about thousands of middle-age men and women who walk regularly for exercise. Recruited beginning in 1998 at walking events and from lists of subscribers to walking-related publications, these volunteers filled out a lengthy survey about their typical walking distance and pace, as well as their health history and habits.

As most of us would likely guess, walking is the most popular physical activity in America. But people who walk for exercise do so at wildly varying speeds and intensities. Some stroll at a leisurely 2 miles per hour, which is low-intensity exercise. Others zip along at twice that pace or better, resulting in a sweatier workout.

Exercise guidelines generally suggest that for health purposes, people should engage in 30 minutes of moderate-intensity activity most days of the week. For walkers, a moderately intense pace would probably be about 15 or 16 minutes per mile.

It has generally been assumed that if people walk more slowly but expend the same total energy as brisk walkers — meaning that they spend more time walking — they should gain the same health benefits. But few large-scale studies have directly compared the impact of moderate- and light-intensity walking, especially in terms of longevity.

To do so, Paul T. Williams, a statistician at Lawrence Berkeley National Laboratory, gathered data about 7,374 male and 31,607 female participants from the walkers’ health study, who represented almost every speed of fitness walker, from sluggish to swift. His findings were published online this month in PLoS One.

Dr. Williams divided participants into four numerically equal categories, based on their normal pace. Those in Category 1, the fleetest, averaged less than 13.5 minutes per mile, putting them on the cusp of jogging, while those in Category 4, the slowest, strolled at a relatively dilatory 17 minutes or more per mile. The majority of the walkers in this group in fact required at least 20 minutes to complete a mile, and many had a pace of 25 minutes or more per mile. (Interestingly, on average, female walkers were faster than men in all of the categories.)

Next, Dr. Williams cross-referenced his data against that in the essential if somewhat ghoulish National Death Index to determine which of the almost 39,000 walkers had died in the decade or so since they had joined the survey and from what.

It turned out that nearly 2,000 of the walkers had died. More telling, these deaths disproportionately were clustered among the slowest walkers. Those in Category 4 were about 18 percent more likely to have died from any cause than those in the other three categories and were particularly vulnerable to deaths from heart disease and dementia.

Unexpectedly, the death rate remained high among the slowest walkers, even if they met or exceeded the standard exercise guidelines and expended as much energy per day as someone walking briskly for 30 minutes. This effect was most pronounced among the slowest of the slow walkers, whose pace was 24 minutes per mile or higher. They were 44 percent more likely to have died than walkers who moved faster, even if they met the exercise guidelines.

One important inference of these statistics is that intensity matters, if you are walking for health. “Our results do suggest that there is a significant health benefit to pursuing a faster pace,” Dr. Williams said. Pushing your body, he said, appears to cause favorable physiological changes that milder exercise doesn’t replicate.

But there are nuances and caveats to that conclusion. The slowest walkers may have harbored underlying health conditions that predisposed them to both a tentative walking pace and early death. But that possibility underscores a subtle takeaway of the new study, Dr. Williams said. Measuring your walking speed, he pointed out, could provide a barometer of your health status.

So check yours, your spouse’s or perhaps your parents’ pace. The process is easy. Simply find a 400-meter track and, using a stopwatch, have everyone walk at his or her normal speed. If a circuit of the track takes someone 6 minutes or more, that person’s pace is 24 minutes per mile or slower, and he or she might consider consulting a doctor about possible health issues, Dr. Williams said.

Then, with medical clearance, the slow walkers probably should try ramping up their speed, gradually.

The most encouraging news embedded in the new study is that longevity rises with small improvements in pace. The walkers in Category 3, for instance, moved at a speed only a minute or so faster per mile than some of those in the slowest group, but they enjoyed a significant reduction in their risk of dying prematurely.

Source: New York Times

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Older men who spend a lot of time sitting around are more likely to face heart failure down the road, a new study shows. The research included more than 82,000 men between the ages of 45 and 69. Those who spent more time being sedentary outside of work hours, even if they exercised, had a higher risk for heart failure. “Men with low levels of physical activity were 52 percent more likely to develop heart failure than men with higher levels of physical activity,” said study author Deborah Rohm Young, a senior scientist at Kaiser Permanente in Pasadena, Calif. Young said those who spent at least five hours per day sitting were 34 percent more likely to develop heart failure than those who spent less than two hours a day sitting. The scientists used data from a large study called the California Men’s Health Study. None of the men had heart failure at the start of the study. “We looked at baseline information on a questionnaire about physical activity and sitting time outside of work,” said Young, who noted that the men were followed for up to a decade. Their exercise levels were calculated in a way that tallied how much energy the body uses. The researchers also tracked how many hours a day the men were sedentary. “Those who had low physical activity — who sat a lot and got little exercise — were more than twice as likely to have heart failure compared to those who were active and had not very much sitting time outside of work,” Young explained. Heart failure is the inability of the heart muscle to effectively pump blood throughout the body, said Young. It affects 5.7 million Americans — mostly older people. Approximately 20 percent of adults will be diagnosed with it during their lifetime, according to the American Heart Association. “It affects a lot of people. Of those who have heart failure, about half will die within five years of being diagnosed,” Young said, noting that transplants are rare and most with the condition manage it through medication. “But it is associated with a reduced quality of life.” Young said that even when she and her colleagues looked at people who developed heart disease or high blood pressure during the study, they found that being more active was still good. “It was more likely to protect against heart failure for those who had those conditions.” For those with heart issues who want to increase their exercise, it’s not too late, she said, although, “obviously they have to get a clearance from their physicians before changing their physical activity.” The take-home message is simple, Young said: Sit less, move more. “It doesn’t even require joining a gym,” she said. “Walking is the best exercise for the majority of people. Brisk walking. Thirty minutes a day is wonderful.”

Source: HealthDay

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