The work-up and holistic view of the short-and long-distance triathlon with all its differences and specificities is represented with this work. We encountered - despite a lot of already known information - on many new insights. We could integrate them into the work. We have found out through interviews and experience reports that the Ironman general and in particular the Ironman Hawaii is the biggest challenge for athletes. We have also found out that the two world organizations (ITU, WTC) have developed their various formats since the early years in two different directions. The Ironman still enjoys great popularity and has become a kind of mass sport. "Everybody can Ironman" and "Everybody", who comes into contact with triathlon, will not make "only" triathlon but Ironman. The shorter distances are often used here as "pure" entry competition. We have showed for a better understanding the general topic ?endurance in sport? and the associated chapter of training ranges, training methods - as well as the intensity and periodization and performance analysis in the sport of triathlon. Here we have also addressed the differences between short- and long-distance triathlon. On the other hand, our work also shows that the performance of development is paced massively forward when one compares, for example, the winning times of the Hawaii Ironman World Championship in the early years and in the last few years. Not only is the material difference in these two distances, but also in training and competition schedules are big differences. The described aspects of the technique are for both distances valid. In our last chapter we responded the importance of mental training in the sport of triathlon. We presented the main problems that can arise in a race,/before a race or in training, and we showed the possible solution variants from the mental training.