Both the men and the women laid down belly fat. "We studied postmenopausal women, so they were gaining visceral fat aggressively," he notes. Before you know it, your slacks are snug.
"People don't realize that inactivity is not a steady state," says Slentz. "They think it would be nice to start exercising, but if they think about it for six months, they've gained another pound. or two and an 8 percent increase in visceral fat."
How much activity is enough to stop gaining? It depends on who you are.
"If you're trying not to become overweight or obese, it looks like 45 to 60 minutes a day," says Harvard's I-Min Lee. But the story is different for people who used to be chubby.
"Individuals who are overweight and have lost weight need more physical activity to maintain the weight loss than people who don't want to gain weight, because if you've already become overweight, you're in an at-risk group," she notes. "Those people probably need 60 to 90 minutes a day to avoid regaining weight."
If that sounds about as realistic as going to medical school in your spare time, don't despair. "That's based on formerly obese individuals who lost 30 to 50 pounds and kept it off," says Blair. "You don't need 90 minutes a day to keep five pounds off."
What's more, it's not as though half an hour a day doesn't count. "Just 30 minutes a day is sufficient to reduce the risk of many chronic diseases," says Lee.
10 Immune System
Regular exercise may boost the immune system ... unless you overdo it. One indicator: how often people get colds.
"In moderate amounts, physical activity reduces the risk of upper respiratory tract infection," says Lee.
In studies that use older or middle-aged individuals, 30 to 45 minutes of walking about five days a week is moderate, she adds.
But the tables are turned if you go to extremes.
"Marathon runners have a higher risk of colds after a race, because immune function goes down after a prolonged intense bout of exercise," says Lee.
The picture is similar for inflammation, which can be a sign of weakened immune function.
"It's very complicated, but it looks like regular exercise can decrease inflammation," says the University of Maryland's Ben Hurley.
On the other hand, playing a hard game of basketball or soccer once a month can boost inflammation if that's all you do.
"The weekend athlete who does something strenuous once in a while can do more harm than good to a lot of systems," says Hurley. "You have to perform vigorous activity at least two or three times a week to avoid making things worse."
The Bottom Line
* To lower your risk of heart disease, diabetes, and colon cancer, shoot for at least 30 minutes a day of moderate-intensity aerobic exercise like brisk walking, cycling, jogging, or swimming.
* To keep off substantial amounts of lost weight, shoot for 60 to 90 minutes a day of moderate-intensity aerobic exercise.
* To build muscle and prevent bone loss, do strength training exercises at least twice a week using weights you can lift no less than 8--but no more than 15--times.
Showing posts with label immune system. Show all posts
Showing posts with label immune system. Show all posts
Thursday, July 2, 2009
Nutrition Action article - Inactivity- page 1
Planning to exercise more? Been planning on it for a while?
It's easy to put off, at least today, at least this week, at least until you (choose one) get new sneakers, get past the holidays, get some free time, get a new job, get the kids off to college, whatever.
But as the years slip by, your body isn't just frozen in time, waiting to get moving. It's fading.
"If muscle isn't stimulated, your body senses that you don't need it," explains Miriam Nelson of Tufts University in Boston. "Metabolically, it's expensive to keep up so you start to lose it."
Muscle is just the beginning, she adds. "Inactivity affects the brain, heart, blood vessels, bones, liver, gut, sleep, anxiety, depression, self-esteem, your ability to use glucose, and more."
More Articles of Interest
Give me strength: why you need to lift weights
Glycemic index & weight
"From the top of your head to the bottom of your toes, being physically active is the stimulus that gets most organs in the body to work at their best," says Tufts University exercise expert Miriam Nelson.
"If you're not active, it affects all body systems, literally down to the cellular level, where your ability to transfer oxygen from the bloodstream to cells is diminished and the number of power-producing mitochondria in your cells is less."
"If you can't get as much oxygen out of your blood, you can't walk up a flight of stairs as easily as you get older." And that's just one system that suffers if you're sedentary.
The good news: it's never too late to start moving. "Well into your 90s, all of these systems can be stimulated," notes Nelson. "It's quite remarkable."
Here are 10 ways inactivity can take a toll on your body.
1 Diabetes
"The one thing that seems to deteriorate quickest with inactivity is insulin sensitivity," says Ben Hurley, a professor of kinesiology at the University of Maryland at College Park (and husband of Nutrition Action's Jayne Hurley). Fortunately, "it also responds most consistently when you train."
Type 2 diabetes--by far the most common kind--occurs when the body be comes insensitive, or resistant, to insulin in the blood. When insulin stops working, blood sugar levels rise and diabetes sets in.
Regular exercise reverses the damage.
"It increases insulin sensitivity and makes the cells better at taking in glucose and processing it," explains I-Min Lee, an associate professor of epidemiology at the Harvard School of Public Health in Boston.
In a study of more than 50,000 nurses, every two hours a day of TV-watching was linked to a 14 percent increase in the risk of diabetes. (1) Every two hours of sitting at work was linked to a 7 percent increase. In contrast, every hour of brisk walking per day was linked to a 34 percent lower risk.
What's more, when researchers told people with high-but-not-yet-diabetic blood sugar levels to do aerobic exercise for at least 2 1/2 hours a week and lose at least 7 percent of their body weight, their risk of diabetes was 58 percent lower than similar people who didn't exercise or lose weight. (2)
"The data are striking," says Hurley. And it's not just an issue for adults. "Type 2 diabetes used to be a disease of middle age," he adds. "But now we're seeing it in young people. It's a sedentary disease."
Hurley sounds like researcher Steven Blair talking about the metabolic syndrome, which raises the risk of both diabetes and heart disease. Doctors diagnose the syndrome when people have a large waist, low HDL ("good") cholesterol, and elevated (though not necessarily high) blood pressure, blood sugar, and triglycerides.
"The metabolic syndrome is misnamed," says Blair, who is president of the Cooper Institute in Dallas, Texas. "It ought to be called the inactivity syndrome."
2 Cancer
"The evidence is fairly clear now that men and women who are physically active have a 30 to 40 percent lower risk of colon cancer compared to individuals who are not active," says Harvard's I-Min Lee, who examined dozens of studies. (3)
Experts have several theories that might explain how physical activity protects the colon. "It increases transit in the intestine, which makes food flow through fast," says Lee. "So any carcinogens in the intestine have less contact with the cells that line the intestine."
Another possibility is that regular exercise shores up the immune system. "That would protect the body from any cancer, including colon," she adds,
Hormone-like substances called prosta glandins might also play a role. "Activity can decrease prostaglandin E2 levels in the intestinal cells," says Lee. "Prostaglandin E2 is associated with a higher risk of colon cancer," she notes, probably because it makes colon cells proliferate faster and slows intestinal motility.
Then there's the obvious: "Physical activity prevents weight gain, and the overweight have a higher risk of colon cancer," says Lee.
How much movement is enough? "We don't have precise data, but it looks like you need 30 to 60 minutes a day of moderate-intensity physical activity."
Regular exercise also appears to lower the risk of breast cancer by about 20 percent. (4) "But the research has been somewhat inconsistent," says Walter Willett, chair of the nutrition department at the Harvard School of Public Health.
It's easy to put off, at least today, at least this week, at least until you (choose one) get new sneakers, get past the holidays, get some free time, get a new job, get the kids off to college, whatever.
But as the years slip by, your body isn't just frozen in time, waiting to get moving. It's fading.
"If muscle isn't stimulated, your body senses that you don't need it," explains Miriam Nelson of Tufts University in Boston. "Metabolically, it's expensive to keep up so you start to lose it."
Muscle is just the beginning, she adds. "Inactivity affects the brain, heart, blood vessels, bones, liver, gut, sleep, anxiety, depression, self-esteem, your ability to use glucose, and more."
More Articles of Interest
Give me strength: why you need to lift weights
Glycemic index & weight
"From the top of your head to the bottom of your toes, being physically active is the stimulus that gets most organs in the body to work at their best," says Tufts University exercise expert Miriam Nelson.
"If you're not active, it affects all body systems, literally down to the cellular level, where your ability to transfer oxygen from the bloodstream to cells is diminished and the number of power-producing mitochondria in your cells is less."
"If you can't get as much oxygen out of your blood, you can't walk up a flight of stairs as easily as you get older." And that's just one system that suffers if you're sedentary.
The good news: it's never too late to start moving. "Well into your 90s, all of these systems can be stimulated," notes Nelson. "It's quite remarkable."
Here are 10 ways inactivity can take a toll on your body.
1 Diabetes
"The one thing that seems to deteriorate quickest with inactivity is insulin sensitivity," says Ben Hurley, a professor of kinesiology at the University of Maryland at College Park (and husband of Nutrition Action's Jayne Hurley). Fortunately, "it also responds most consistently when you train."
Type 2 diabetes--by far the most common kind--occurs when the body be comes insensitive, or resistant, to insulin in the blood. When insulin stops working, blood sugar levels rise and diabetes sets in.
Regular exercise reverses the damage.
"It increases insulin sensitivity and makes the cells better at taking in glucose and processing it," explains I-Min Lee, an associate professor of epidemiology at the Harvard School of Public Health in Boston.
In a study of more than 50,000 nurses, every two hours a day of TV-watching was linked to a 14 percent increase in the risk of diabetes. (1) Every two hours of sitting at work was linked to a 7 percent increase. In contrast, every hour of brisk walking per day was linked to a 34 percent lower risk.
What's more, when researchers told people with high-but-not-yet-diabetic blood sugar levels to do aerobic exercise for at least 2 1/2 hours a week and lose at least 7 percent of their body weight, their risk of diabetes was 58 percent lower than similar people who didn't exercise or lose weight. (2)
"The data are striking," says Hurley. And it's not just an issue for adults. "Type 2 diabetes used to be a disease of middle age," he adds. "But now we're seeing it in young people. It's a sedentary disease."
Hurley sounds like researcher Steven Blair talking about the metabolic syndrome, which raises the risk of both diabetes and heart disease. Doctors diagnose the syndrome when people have a large waist, low HDL ("good") cholesterol, and elevated (though not necessarily high) blood pressure, blood sugar, and triglycerides.
"The metabolic syndrome is misnamed," says Blair, who is president of the Cooper Institute in Dallas, Texas. "It ought to be called the inactivity syndrome."
2 Cancer
"The evidence is fairly clear now that men and women who are physically active have a 30 to 40 percent lower risk of colon cancer compared to individuals who are not active," says Harvard's I-Min Lee, who examined dozens of studies. (3)
Experts have several theories that might explain how physical activity protects the colon. "It increases transit in the intestine, which makes food flow through fast," says Lee. "So any carcinogens in the intestine have less contact with the cells that line the intestine."
Another possibility is that regular exercise shores up the immune system. "That would protect the body from any cancer, including colon," she adds,
Hormone-like substances called prosta glandins might also play a role. "Activity can decrease prostaglandin E2 levels in the intestinal cells," says Lee. "Prostaglandin E2 is associated with a higher risk of colon cancer," she notes, probably because it makes colon cells proliferate faster and slows intestinal motility.
Then there's the obvious: "Physical activity prevents weight gain, and the overweight have a higher risk of colon cancer," says Lee.
How much movement is enough? "We don't have precise data, but it looks like you need 30 to 60 minutes a day of moderate-intensity physical activity."
Regular exercise also appears to lower the risk of breast cancer by about 20 percent. (4) "But the research has been somewhat inconsistent," says Walter Willett, chair of the nutrition department at the Harvard School of Public Health.
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