Triathlon athletes have varying distances to compete in from shorter sprint races to longer Ironman distance events. As the events progress from sprint to Olympic to Ironman distance the percentage of time spent in each discipline (swim, bike, run) adjusts with the distance. Research has shown when comparing the Olympic and Ironman distances athletes will spent a greater percentage of their time running with the longer races while the biking percentage stays relatively stable (Lepers et al. 2013). Not surprisingly, an athletes time spent during the biking and running sections, due to their duration, has the greatest impact on an athlete's time and performance. These are often the areas where athletes can have the greatest impact on their overall performance.
A recent study in the Journal of Strength and Conditioning Research examined the impact of each of the three disciplines on Olympic and Ironman triathlon performance (Figueiredo et al. 2016). The authors analyzed performances from the top 50 male and female triathlon finishers over a 26 year period. Within the Olympic distance races the authors noted significant decreases in both swim and run times, but both bike and run times significantly became faster within the Ironman races. Within the Olympic distance, the run followed by the bike discipline showed the greatest impact on overall performance, but these disciplines had similar contributions to performance in the Ironman event.
This study indicates the importance of focusing on run performance in the Olympic distance, but Ironman athletes should focus on both the run and bike disciplines to improve their performance.