What Effect Does Age Have On Ironman Finishing Times? An In-Depth Statistical Analysis.

If youth knew; if age could.
– Sigmund Freud

We all age. It beats the alternative, as the saying goes. But what effect does this have on our triathlon performance? I’ve reviewed approximately 14,000 finishing times from Ironman races in an attempt to discern exactly how age affects Ironman finishing times. Let’s get started.

As a baseline, the average Ironman finishing time for all finishers was 12:41:30. But what happens when we look at the results by age group?

 

The chart above shows each age group’s average minutes over the 12:41 baseline Ironman time. We can clearly see a pattern in which the best results are notched in the 30-34 age group, while those athletes over 45 tend to be slower than the overall average. In fact, when analyzing each of these results individually, age is unsurprisingly correlated as a predictor of finishing time.

Time Correlation to age*
Overall time 0.20
Swim time 0.17
Bike time 0.15
Run time 0.20

* For athletes at least 35 years old

It is immediately obvious that this is a pattern which affects all three events nearly equally. While it’s important not to conflate correlation with causation, and keeping in mind that these results could be a factor of training time, family obligations, work stress, or any of the numerous factors which evolve as we age, this seems to be a very clear-cut result.

Let’s dig into these results a bit more on an event-by-event basis. Here are the averages for all Ironman finishing results analyzed:

Event Average Time
Swim 1:18:33
T1 7:54
Bike 6:22:02
T2 7:22
Run 4:45:37
Total 12:41:30

How does each age group do on the swim?

 

In regards to the swim portion of an Ironman, we can see on the chart above that the “young athlete” underperformance in overall Ironman finishing times does not hold when looking at swim times alone. This makes sense, because while it requires years and years of hard training to teach your body to efficiently perform throughout the duration of a 10-14 hour race, the swim only lasts a bit more than an hour. For this reason (and Ironman purists may shout at me for this), the swim can more easily be “faked”, i.e., an adequate time is achievable with many fewer training hours less and experience than the bike and run require.

Speaking of the bike and run…

 

The chart above shows us that cycling and running times are very reminiscent of the results for overall finishing time. Teenagers haven’t yet put in the years of training needed for competitive times, and athletes in their 30s turn in the best results. After the clock ticks over to 40, cycling and running times unilaterally increase with age. Sorry folks.

But what about transitions? After all, they account for nearly 15 minutes of the average Ironman time.

This analysis shows us that transition times are highly correlated with age as well. If you’re on the back side of 40, this is a good thing! Keep practicing your transitions so they remain smooth and efficient, and you’ll gain an advantage of at least a few minutes over everyone else in your age group.

At this point, I’d be remiss if I didn’t throw gender into the mix. Are men and women equally struck by the age-related decline in Ironman performance? Short answer: No! First, let’s look at overall performance by gender.

Event Men’s Average Women’s Average
Swim  1:17:50  1:20:31
T1  7:49  8:09
Bike  6:16:31  6:36:56
T2  7:19  7:30
Run  4:41:14  4:57:30
Total 12:30:42  13:10:37

How do men and women do with respect to their gender’s average time when taking age group into effect?


(15-19 and 70+ age groups removed for insufficient women’s data)

We see above that while men in their 30s perform better than their female counterparts versus each gender’s average time, men slow down much, much more as they age. In fact, the effect appears to be nearly double in terms of minutes lost. Wow.

The logical follow-up question is: where does this slow-down occur?

There appears to be no good news for men here. It’s apparent that men over 40 slow down more in each event than their female counterparts as they age. We can show this differently with our trusty correlation table.

Time Correlation to age (Men) Correlation to age (Women)
Overall time 0.23 0.10
Swim time 0.20 0.08
Bike time 0.19 0.04
Run time 0.23 0.14

* For athletes at least 35 years old

This table shows us that while all triathletes over 35 years old post slower times as they age, women triathletes slow down much less, on average, than men.

These results may not be surprising, but they can be a bit bleak when presented starkly in graphical form. Remember that these averages are just that – averages. There’s no reason you can’t improve your performance and set PRs, whether you’re 21 or 51.

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