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Past Shows
February 4, 2006
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Exorcizing Myths about Exercise
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Lifting weights |
It's well known that exercise is good for you in almost every way, but there are a lot of myths around exercise that science has been illuminating. We follow our host, Bob McDonald, through a workout and bust some of these myths.
First on the agenda is stretching. For decades stretching has been seen as an essential preliminary to a workout. But according to Dr. Ian Shrier of the faculty of Medicine at McGill University, and past president of the Canadian Academy of Sport Medicine, that's old, and bad, advice. Research has shown that pre-workout stretching decreases performance and doesn't protect against injury.
Dr. I-Min Lee, a professor at Harvard Medical School and the Harvard School of Public Health has studied people who pack all their exercise into one weekend binge. She discovered that if you have any risks for heart disease, being a weekend warrior is as bad as getting no exercise at all.
Most surprising is that exercise can have no effect at all on some people. Dr. Claude Bouchard, Executive Director of the Pennington Biomedical Research Center in Baton Rouge, Louisiana, discovered early in his career that there's enormous variation in how people respond to cardiovascular exercise, with some not responding at all. His current research is aimed at discovering the genetic roots of this phenomenon. Dr. Eric Hoffman, Director of the Research Center for Genetic Medicine at the Children's National Medical Center in Washington, DC, has found a similar phenomenon with muscle. Both say, however, that there are health benefits with exercise, even if cardiovascular fitness and strength don't improve.
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Pregnancy and Male Monkey Dads
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Marmoset monkeys at the Wisconsin National Primate Center - Courtesy, Jeff Miller |
What makes a good father? Perhaps one who is sympathetic to his mate’s needs, her wants, and her pregnancy complaints. In her research into primate fathering traits, Dr. Toni Ziegler, senior scientist at the Wisconsin National Primate Research Center, has shown that male marmoset and tamarin monkeys go further than that -- they gain weight when their partners are pregnant. They show increased levels of the hormone, Prolactin, too. And the weight gain could be caused by the release of hormones, triggered by the female's pregnancy. The researchers suggest that the monkey dads may be packing on the pounds in preparation to help care for their infants. Male marmoset and tarmarin monkeys help care for their young, carrying them around for weeks after their birth.
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Feeding Seals to Condors
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A group of California condors feast on a carcass - Courtesy, Stanford University |
The biggest killer of endangered condors today is lead poisoning. The giant scavenger birds ingest lead when they eat animal carcasses. So, a group of scientists is proposing a change in diet. They believe that the California condors should eat seals, sea lions, and whale carcasses instead of deer carrion that can contain lead shot from hunters' attacks. The idea isn’t so far-fetched when you understand that ancient condors did eat the carcasses of sea mammals after the last Ice Age, when their traditional diet of mastadons and mammoths was killed off. Dr. Page Chamberlain, chair of the department of Geological and Environmental Sciences at Stanford University, was part of a team that analysed bone and feather samples from condors from hundreds of years ago to trace their diet changes over time. He’s hopeful that reverting back to a seafood diet will ensure a future for the endangered bird.
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Sizing Up the 10th Planet
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Size comparison, UB313, Pluto, our Moon and Earth - Courtesy, F. Bertoldi |
In the middle of last summer, a new addition to the solar system was identified. Dubbed 2003 UB 313, this object was further from the sun than anything seen before, and appeared to rival Pluto in size. But beyond that, not many details were known. The object was submitted to the International Astronomical Union for proper classification and naming. Scientists wondered, should this be considered a tenth planet? Not much happened with UB 313 until this past week, when a European group of scientists, led by Dr. Frank Bertoldi, from the University of Bonn in Germany, announced the object's size. It's about 3,000 km in diameter, making it larger than Pluto's 2,300 km. This, says Dr. Bertoldi, is enough to justify this object being classified as a planet.
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