Coaches and trainers striving to keep their players fit and keep injuries to a minimum have added wireless heart rate monitoring units to their list of equipment.

Among well-known athletes who have used the monitors are cyclist Greg LeMond, the three-time Tour de France champion; Norway's Ingrid Kristiansen, the world's fastest woman's marathoner; and Mark Allen, winner of the Ironman Triathlon. Teams or organizations that have used them include pro football's Chicago Bears, pro hockey's Los Angeles Kings, the U.S. Biathlon Association, the U.S. Olympic Training Center and the U.S. Shooting Team.The death of college basketball star Hank Gaithers of Loyola-Marymount heightened the need for thorough testing and evaluation of athletes.

George Grippo, president of Polar USA, the Stamford, Conn., company that is the leader in heart monitoring equipment, estimates 100,000 units are being used by athletes and teams.

Studies published in the journal Physician and Sportsmedicine and the New Zealand Journal of Sports Medicine indicate excellent correlation between readings obtained by wireless monitors and hospital hard-wire monitors.

Dr. Kenneth Cooper, director of the Aerobic Center in Dallas, says the units are valuable for cardiac rehabilitation programs in which the exercisers have to know when they've reached their optimum heart rate.