AN EXERCISE AFICIONADO knows the importance of working out in his or her target heart-rate zone during a cardiovascular session. But how do you know if you've reached the proper level, or whether you're maintaining it throughout the workout? Well, with a little help from microcomputer technology, it's easy: Just strap on a Polar heart-rate monitor.
Polar USA offers six wireless models (priced from $149 to $495) that work on the same principle as an electrocardiograph (ECG). During exercise, an elastic band with embedded electrodes is worn just below the pectoral muscles. A transmitter sends electronic signals directly to a monitor, which is worn on the wrist or mounted on a stationary bike, rower or treadmill. A digital readout on the monitor graphically displays the user's heart rate in beats per minute.
