Conditioning for triathletes Triathlon is an endurance sport that involves disciplines of swimming, bicycling and running, with transitions between them. The last couple of years triathlon has been one of the fastest growing sports in the World, and just how popular it has become also shows the fact that in America the number of children training in it has increased, and there are triathlon camps and competitions for children as young as 6 years old. Triathlon has been part of the Olympic games since the 2000 Olympics in Sydney. There are multiple disciplines in triathlon, that differ in the distances that need to be completed. For adults those start with the Super Sprint, which consists of a 375 m swim, 10 km bicycling segment, and a 2.5 km run, all the way to more extreme formats such as a combined distance of 10 Ironman triathlons. For example, the Super Sprint triathlon is a short and fast discipline that significantly involves the anaerobic system, while the aerobic system satisfies the energy needs of activities that are lower in intensity and greater in duration. In this thesis I will describe a microcyle of the preparatory phase in the base conditioning period during the 3rd month, a microcyle in the 5th month of specific and situational conditioning, and the circular training for a junior athlete that is transitioning into seniors, that is, from the discipline of Super Sprint triathlon to Olympic triathlon.