Triathlon Focuses on Three SportsA triathlon is an athletic event that includes swimming, running, and cycling. The triathlete therefore must focus his or her training on all three parts. There are actually five different lengths of triathlons; they range from short and doable to crazy-long.Training requirements increase as the triathlete works his or her way up the food chain. A sprint version requires the triathlete to swim ½ mile, bike 12.4 miles and run 3.1 miles. As they improve their a.