Ice hockey requires anaerobic power, aerobic conditioning, strength, agility, and speed. Similar to other in- termittent, high-intensity sports, there are constant changes in speed and direction, but ice hockey diff ers from soccer or basketball in that there is full body contact. A game consists of three 16-minute periods, but frequent player substitutions reduce playing time to at least half of the game time. Learn more about the sport at the websites for the National Hockey League (www.nhl.com) and USA Hockey (www.usahockey .com).