Answered by Ingrid Ducmanis on Thursday, January 28, 2010
Once your body gets used to a routine, it essentially switches to autopilot—meaning it's not challenged anymore. Plus, the more you do one sport—i.e., running—the more your muscles get used to it, and the harder it will be to do other activities. "To avoid monotony, mix things up so you also won't lose your motivation," says Joe Quatrochi, Ph.D., an exercise physiologist and health promotion specialist at the Metropolitan State College of Denver. The same holds true for resistance training, where it's even more important to mix up the exercises you do. "If you stick with just one exercise to work a particular muscle, whole regions of that muscle can remain unengaged," explains Quatrochi. For example, if you're only doing a flat bench press for your chest, the upper and side chest muscles will be underused. A simple way to correct that would be to incorporate some bench presses on an incline bench to engage the upper part of the muscle, and widen your grip to employ the fibers along the side.