Even if you didn't make the cut for this year's Olympic Games in Greece, you can train like a world-class athlete with pocket-sized electronics that deliver a pumping music beat while keeping track of your rising pulse rate.
These gadgets, many of which pull double duty as a radio, music player or regular timepiece, can act as part-time coach and motivator shouting out numbers on the distance you have run or cycled, and indicating that your breaststroke needs work.