Last month, we looked at some historical data on bike splits at the Ironman World Championships in Kona. That examination led to some interesting finds:
- Athletes don't appear to be generating significantly more power than they did 10 years ago.
- Bike splits for both the top finishers and the overall field have decreased substantially from a decade ago.
- The rate of decrease in bike splits seems to have dropped off.
This indicates that bike aerodynamics have led the advancement of performances on the World Championship course, but there may not be much left to improve upon. Bike technology may have reached the "as good as it gets" point.
This may mean that athletes hoping to break the Kona course record will have to look elsewhere—the swim and the run—for time bonuses. The plot graph below shows how things have progressed in those disciplines for Kona winners since 1988.
The blue dots indicate specific swim splits each year, while the red line shows the trend over time. The line makes it look like the winners are swimming slower over time, but this is where we get into the nuts and bolts of data analysis.
Notice that in the top right portion of the graph, there's a formula expressing the equation of the line. Below that is R2, which accounts for how accurate our line is. Think of it as a percentage that describes if the graph is a good description of the trend. In this graph, it's only 7.5-percent, which means it's not very accurate.
So why even bother to use it? Because it actually helps to make an important point: there isn't a real trend in swim times among Ironman champions.