Amy Postle/FITNESS MagazineBy Peg Rosen
I've spent years handpicking a posse of Spinning instructors, yoga teachers, and cross-trainers I can trust. They're smart; they're certified. They know the ins and outs of asanas, ab crunches, and aerobic conditioning. But how much stock should I put in the health information and advice some of them dole out during sessions? You know, like what I should be eating or how certain exercises might benefit my brain.
Organizations that train and certify trainers warn their members not to cross the line that separates fitness tips from health advice. "The line is thin, but trainers still have to respect it," says Grace DeSimone, editor of the American College of Sports Medicine's Resources for the Group Exercise Instructor. "For example, it's OK to talk about the basics of good nutrition. But it is absolutely not OK to tell someone to avoid a specific food group, like dairy, unless the trainer also happens to be a registered dietitian." Likewise, if something hurts while you're exercising, an instructor may be trained to provide basic modifications. But if you're still in pain, she should refer you to a doctor.
As for all of those health claims, are you wondering if what you've been told is fit to be trusted? Here's the skinny on some of the top myths muscling their way around gyms right now.
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"Heat and vigorous exercise help you sweat out toxins."
You aren't likely to purify your body of much of anything by sweating, whether in a hot yoga class or sizzling sauna, because all that's in perspiration is water, salt, and a smattering of electrolytes, according to Rachel Vreeman, MD, author of Don't Cross Your Eyes...They'll Get Stuck That Way! "Sweat glands sit in the skin and aren't connected to other systems in the body, so it makes no sense that they would eliminate waste," she says. "The only role of perspiration is to keep us cool." The body does a pretty good job of getting rid of what it doesn't need, largely through the liver, kidneys, and digestive tract. There's nothing special you have to do to help, other than eat well, stay hydrated, and keep fit so those organs can function properly.
"The more limber you are, the better."
Even when trainers tell you not to force things, there's an implicit message that your eventual goal is a greater stretch. If you can touch your knees now, you should be aiming for the floor. If you can touch the floor today, work toward hugging your chest to your knees. But achieving those goals may offer nothing more than bragging rights. "Flexibility is certainly important, and you should be flexible enough to do the things you need or want to do without being uncomfortable," says Jo A. Hannafin, MD, PhD, orthopedic director of the Women's Sports Medicine Center at the Hospital for Special Surgery in New York City. "But there is no health benefit in having a hyperflexible body or being able to twist yourself into a pretzel just for the sake of doing so." In fact, pushing your body into extreme stretches can cause injury. People with tremendously lax joints may be at greater risk for hurting themselves because their ligaments can't effectively keep their joints in position, explains Polly de Mille, an exercise physiologist who works with Dr. Hannafin.
"A cool-down after your workout minimizes muscle soreness."
For years researchers believed that lactic acid buildup during rigorous exercise was what caused our muscles to ache later. Their solution: a few minutes of walking or stretching to help disperse the lactate to other parts of the body. It's a concept that's alive and well today, despite the fact that reams of research have proved that lactate buildup has little to do with postexercise muscle soreness. "There is some evidence that after intense exercise, a cool-down can help prevent blood from pooling in a person's extremities and reduce their risk of becoming dizzy or passing out," says Carl Foster, PhD, professor of exercise and sport science at the University of Wisconsin-La Crosse. "I would recommend doing it after any class to allow people to get their heart rates down." But don't sweat it if you have to cut out of your session early. "After a moderate workout, walking to the locker room will provide all the cool-down a healthy person needs," Foster says.
"You should replace your sneakers every six months to avoid injury."
During a typical five-mile outing, the average runner's feet will strike the ground -- and compress the shock absorbent padding in her shoes -- about 7,000 times. Cushioning and uppers will wear out, potentially providing less support for ankles and feet. And worn treads raise the risk for skids and falls. So replacing sneakers every 300 to 500 miles, or roughly every three to six months, is a common and sensible guideline for avid runners. "Trainers who advise this as a general rule, however, aren't taking into account that people who exercise indoors or run fewer miles simply don't put that kind of stress on their shoes," says Rob Conenello, president of the American Academy of Podiatric Sports Medicine. He suggests replacing sneakers you use indoors about once a year. Better yet, "every few months, check the soles to make sure the treads aren't worn," he says. "Then take each shoe in your hands and give it a twist. If it twists easily, like a towel, your sneakers probably aren't providing enough support."
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"Perspiration and a high heart rate are signs of a good cardio workout."
Just because a Bar Method class kicks your butt, tones your abs, and leaves you soaked with sweat, it doesn't qualify as a heart-healthy cardio session, no matter what an instructor might tell you. For a workout to deliver true cardio benefits, "it's got to be rhythmic, dynamic activity that utilizes large muscle groups -- for example, those in your legs and upper body -- for a minimum of 20 to 60 minutes, depending on your level of fitness," says Timothy J. Michael, PhD, professor of exercise science at the Western Michigan University in Kalamazoo. We're talking brisk walking, running, or cycling that takes a moderately fit person to 60 to 80 percent of her maximum heart rate on a heart rate monitor. For a rough gauge, use the talk test: "If you are mildly breathless but can carry on a conversation, you are working at a moderately intense pace, which is what you want," says DeSimone of the American College of Sports Medicine. "If you can talk and talk without stopping to take a breath, you're not working hard enough. If you can't catch your breath to speak a sentence, your exercise intensity is too high."
"Performing yoga twists purifies your organs."
Spinal twists do promote flexibility and, according to a 2010 study published in the European Spine Journal, may even help prevent disk deterioration between the vertebrae. But can they really "massage your inner organs," wringing impurities from them so they can then "soak up fresh blood" as teachers say? Yoga masters subscribe to this squeeze-and-soak concept, as do oodles of their disciples. Yet there's little if any significant scientific data to support the idea, according to William J. Broad, author of The Science of Yoga. Most medical experts find the idea of squeeze-and-soak far-fetched. "There's no evidence that you can squeeze out bad things, unless you are taking a pee or a poop, which we hope doesn't happen during class," Dr. Vreeman says. "Yoga provides many health benefits. But nothing indicates that compression of your organs is what's helping."
"Running gives you wrinkles because all that pounding breaks down collagen."
It's an argument that could send just about anyone running...for the nearest low-impact class. Fortunately the idea doesn't appear to have any hard science to back it up. "It sounds anecdotal and speculative," says Joseph M. Gryskiewicz, MD, president-elect of the Aesthetic Society Education and Research Foundation. "Having performed surgery on many women marathoners, I can say that their bodies overall are very toned, which refutes the notion that pounding breaks up collagen." It's true that some runners can look a bit gaunt and somewhat craggier than their Pilates-practicing counterparts. But this is largely due to having less body fat and spending more time in the sun, experts say. All those rays also put runners at greater risk for developing skin cancer. Adequate protection -- wearing protective clothing, a hat, waterproof sunblock of SPF 30 or higher, and wraparound sunglasses labeled as "UV absorption up to 400 nm," which means they block at least 99 percent of UV rays -- is a must, says Debra Jaliman, MD, author of Skin Rules: Trade Secrets from a Top New York Dermatologist.
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"You should keep your heart rate below 140 when exercising while pregnant."
This statement has been attributed to the American College of Obstetricians and Gynecologists, but it never issued the warning. In 1985 it came out with a recommendation about exercise and pregnancy that did not discourage working out but did caution that overly vigorous exercise might deprive a fetus of blood and raise a pregnant woman's core temperature to dangerous levels. Over time the organization has become even more encouraging of exercise, and in 2002 it not only deemed moderate exercise safe for most moms-to-be but also declared it a vital part of prenatal health.
Nonetheless the 140-heart-rate myth lives on. "These days there is no one-size-fits-all heart rate for pregnant women," says James M. Pivarnik, PhD, director of the Center for Physical Activity and Health at Michigan State University in East Lansing. "Once she gets the green light from her physician, a woman can pretty much do whatever her body and lack of symptoms allow her to do." Keep in mind, though, that this isn't the time to step up your fitness routine. As a general rule, it is fine to work to the point of fatigue but not exhaustion. Just about the only off-limits activities are high-impact sports, such as boxing, maximal weight lifting, step aerobics (which may compromise balance), and scuba diving. Use common sense and always check with your doctor first.
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Amy Postle/FITNESS MagazineBy Peg Rosen