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Runners love their water bottles, so it’s unfortunate that everywhere you turn these days there seems to be mounting controversy over their safety. First there was the rumor that washing and reusing disposable plastic bottled water containers could cause cancer. This rumor is unfounded, yet persists in many forms. Usually, these chain emails contain the notion that heating the bottle (as when washing) releases carcinogens called dioxins. Plastic water bottles do not contain dioxin, and washing and reusing them appears to be safe. Plastic bottles may, however, contain bisphenol-a (BPA). It’s less certain what effect this chemical may have on the human body. BPA is widely used in the making of polycarbonate water bottles; these are the hard, nearly unbreakable plastic bottles widely used by runners and hikers, such as those manufactured by Nalgene Outdoor. This chemical, which is also used in the manufacture of baby bottles, sippy cups, and even soda can liners, has made many recent headlines and caused a multinational scare as a possible cancer-causing compound in humans. But before you decide that toxic plastics are lurking in your kitchen, let’s examine everything we know to date about BPA. To date. First off, current research has shown that the amounts of BPA that may migrate into food and beverages from plastic containers are extremely small and are at acceptable limits that are set by regulatory agencies. So what is the origin of this health scare? Concern over BPA has been around for a few years, and last year and again this year two studies emerged that call into question its safety. In July of 2007, a study published in the Proceedings of the National Academy of Sciences found that feeding BPA to female mice changed the color of their babies’ coats. The mice with brown coats grew up with healthy weights, while those with yellow coats grow up to be obese, with a higher susceptibility to cancer and diabetes. In April of 2008, The National Toxicology Program in the United States released a draft report stating that some rats that were fed or injected with low doses of the chemical developed precancerous tumors and urinary tract problems and reached puberty early. While the report said the animal tests provided “limited evidence,” it also noted that the “possibility that bisphenol-a may alter human development cannot be dismissed.” |
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Even for Heart Failure Patients, Exercise is Prescribed
If you have cardiovascular disease (CVD) your odds of going into cardiac arrest or of suffering myocardial infarction (MI) (heart attack) during exercise are increased. But modern medical opinion asserts that the risks are offset by the benefits of exercise for just about everyone. The key components to exercising safely, however, are that the exercise is 1.) habitual, and 2.) performed with an intensity matched to your heart health. The American Heart Association assembled a panel of heart experts late last year to review the data on cardiac arrest and MI during physical activity. The panel, which included cardiologists, exercise physiologists, and nurses, found that those over 40 who died suddenly from exercise were generally men with atherosclerosis—whether known or undiagnosed—in their coronary arteries. (This condition is commonly referred to as “hardening of the arteries.”) Most significantly, those who died of exertion tended to be unfit; for example, a sedentary person who one day engaged in vigorous snow shoveling out of necessity. Since the extensive case review, the AHA has made several recommendations to help ward off exercise-related death among those with CVD. FitNews readers will be pleased, if not exactly surprised, to know that exercise was at the top of the list. It turns out that the best way to improve your heart function if you already have heart disease is to exercise regularly. The AHA recommends 30 minutes of moderate aerobic activity five days a week, plus two days a week of strength and flexibility training. This might mean walking or gardening five times a week, and using weights or performing push-ups or yoga twice a week. But a study published recently in JAMA found that even 15 minutes a day of stationary biking improved the fitness of overweight postmenopausal women after six months. It’s a good idea to speak with your doctor before beginning a regimen if you’ve been sedentary. She may recommend a stress test to find a safe level of activity for you, or suggest certain exercises if, for example, you’ve had lower back pain. And if you’ve recently had MI, coronary artery bypass, or angioplasty you should be supervised in a rehabilitation program for up to three months before exercising on your own. Furthermore, we all know that a proper workout begins with a five-minute warm-up and cool down, but this is especially vital for CVD patients because sudden changes in intensity can trigger a heart attack. The AHA also says that these patients ought not to exercise in excessively cold or hot environments. If you experience chest pain, fatigue, heartburn, breathlessness, ear or neck pain, palpitations, headache, or dizziness, stop exercising and get help immediately.
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editorial board Kenneth Cooper, MD |
board of directors Jeff Harbison, President Executive Director: Dave Watt |
Running & FitNews is published by the American Running Association. Address inquiries to ARA, Attention: FitNews Editor, 4405 East-West Highway., Suite 405, Bethesda, MD 20814 or send e-mail to run@americanrunning.com The American Running Association is a nonprofit educational organization, designated 501(c)3 by the IRS. Running & FitNews provides sports medicine and nutrition information. For personal medical advice, consult your physician. © 2008 The American Running Association. |