In her exploration of the biology and chemistry of physical exercise, Nicola Twilley introduces the reader to Couch Potato Mouse and Lance Armstrong Mouse. Both had been fed a diet consisting almost entirely of fat and sugar and got little exercise. But while Couch Potato Mouse was lethargic, with rolls of visible fat, Lance Armstrong Mouse was lean, taut and active in its cage. It had been fed a daily dose of GW501516 or “516”, a drug that, as Twilley puts it, “confers beneficial effects of exercise without the need to move a muscle.” Whether such drugs will ever prove beneficial for humans remains very much to be seen. GlaxoSmithKline, the developer of the compound, shelved it after mice treated with high doses began developing cancer at higher rates than their drug-free peers. But researchers continue to investigate the possibilities of an “exercise pill” and Twilley visited labs in the United States and the United Kingdom to explore the risks and potential benefits of trying to manipulate the body’s metabolism even as the biological processes unleashed by physical activity remain quite mysterious. She even toyed with taking a dose of “516” herself − chemical supply labs have synthesized it for sale − but a small bottle of the substance remains on her desk, unused and developing a faint yellowish tinge. “The pitfalls and peculiarities of the search for a pill to replace exercise offer a fascinating window into the challenges of bioscience in the eternal search for a fountain of youth,” said judge Dan Vergano of BuzzFeed News. “In the reporting, what was most fascinating to me,” Twilley said, “was the way that the struggle to mimic the benefits of exercise artificially reveals how little we actually understand about the biological mechanisms behind those benefits.”
