On a running path, an iPod can be an indispensable aid, offering inspiration and cadence to exercise. However, on a starting line, it's illegal, a safety hazard and, some say, a threat to the purity and spirit of running itself. San Jose, Calif., area high school coaches discourage portable listening devices at practices, and under national rules, they are not allowed in competition.

iPod on the Run: Musical Inspiration or Dangerous Distraction