Oohh i did a Chat GPT
There is no fixed average drop-off between a standalone marathon and an Ironman marathon, as it can vary depending on individual factors such as fitness, training, and experience. However, research suggests that the physical and mental demands of swimming and cycling in addition to running can result in a slower marathon time during an Ironman race.
One study conducted by Lepers and colleagues (2011) found that the average marathon time of Ironman athletes was approximately 10-20% slower than their personal best standalone marathon time. The study looked at 36 male Ironman triathletes who had completed both an Ironman race and a standalone marathon within the previous 12 months.
Another study by Wüthrich and colleagues (2019) found that the average marathon time for participants in Ironman Switzerland was around 24 minutes slower than their personal best standalone marathon time. The study looked at 157 male participants in Ironman Switzerland who had completed at least one standalone marathon in the previous three years.
It’s worth noting that these studies have limitations and may not be representative of all triathletes or Ironman races. Additionally, there are many factors that can influence marathon performance in an Ironman race, such as the course terrain, weather conditions, and nutrition strategy.
Lepers, R., Knechtle, B., Stapley, P., & Andonie, J. (2011). Analysis of Hawaii ironman performances in elite triathletes from 1981 to 2007. Medicine & Science in Sports & Exercise, 43(2), 337-343.
Wüthrich, T. U., Marty, J., Kerherve, H. A., Millet, G. P., & Verges, S. (2019). Influence of an Ironman triathlon on running mechanics, muscle oxygenation, and energy cost: a field study. Sports Medicine-Open, 5(1), 1-9.