Running Afoul of the Law
Despite the Moving Crew's intimate familiarity with traffic court, our formal legal education is pretty much limited to laws of physics ("a body in motion tends to stay in motion," etc.) and, if we finish our homework in time, watching "Law and Order: Fitness Crime Scene" on cable.
But apparently we've been missing some key classes. In a question we didn't get around to during last week's online chat, a participant asked: "Why is that I can swim at a reasonable pace for at least 30 minutes at a stretch, but couldn't run a mile to save my life, while my friend can run three miles with no problem, but gets out of breath after a few laps [in the pool]? We're both mid-twenties females."
"It's the law of specificity," says Cedric X. Bryant, chief exercise physiologist for the American Council on Exercise. When you practice a certain activity repeatedly, two key things happen: The primary muscles used in that task become more efficient at recruiting and using oxygen for the activity and (assuming your form progresses with practice) your mechanics often improve to the point where you are exerting less effort per stride, stroke, kick, racquet swing, mosquito slap, etc.
The oxygen-use phenomenon, Bryant says, is called peripheral adaptation. "The runner can more efficiently extract oxygen for use in [her] lower-body muscles . . . and the swimmer has more peripheral adaptation in the upper body." And, of course, each woman likely has better mechanics than her peer at the more-practiced sport, in addition to any advantage she gains from genetics or body type.
This is one reason we so often urge you to cross-train: By mixing up your workout routine, you not only distribute strength gains more evenly around your body, which helps protect you from imbalance and overuse injuries, you also stay closer to "in shape" for a variety of activities.
But even single-sport enthusiasts who have ignored that advice aren't too bad off, Bryant says. Once someone has the baseline fitness for one cardio-driven activity, he or she can get in shape for many other sports fairly quickly. "This is actually how a lot of people become triathletes," he says. "They start to swim to give their body a break from the pounding of running, then quickly advance" as swimmers. From there, you're just one $2,000 racing bike and a testosterone injection away from three-sport stardom! (Just kidding. Really.)
In competitive sports, the law of specificity is spun the other way: To get and stay good at one activity, you must do it a lot. Team trainers and coaches break sport-specific training into three main elements: strength, speed and agility (or coordination). For example, while an NFL cornerback and a marathon runner may both be in top fitness, one focuses his training on explosive acceleration and nimbleness, while the other works to build slog-it-out endurance. Sure, each will develop skills useful in numerous sports, but the training regimens for those two individuals will differ significantly.
The takeaway? By all means, choose activities you enjoy, and train to excel at your favorite sports. But try to work cross-training into your routine and don't be surprised if all those years of tap dancing leave you poorly prepared for the annual mud-wrestling contest at your family reunion.
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-- John Briley