Ironman New Zealand 2013: A Deeper Look at the Run

There is something deeply unsatisfying about observing what you believe to be a pattern without a good explanation for it. The example in this case is the seemingly poor – relative – performance of men under 40 at Ironman New Zealand. At least when I examined the times for the top 20 placings over the weekend, men in those categories were consistently slower than the expected averages. I’d assume a slow race and be satisfied with that were it not for other age divisions showing better than average performances and a course record being set. With race day heat as a possible candidate for blunting performances I wondered if I could see any evidence for this by looking at splits in more detail.

The initial idea was to examine the detailed run splits for deterioration in pace; I would expect issues with heat (along with pacing and nutritional errors) to have their biggest impact in the latter half of the marathon. On a practical level the fact there was only detailed split data for the run – and even that was missing one timing point – limited further analysis anyway.

Ironman New Zealand 2013: Average Marathon Pace by Age Group

The charts above show the average run pace (in minutes/kilometre) by age group at each timing mat. There was no data for the 35K mat so pacing at that point is extrapolated. Some of the variation in pace can be explained by the imprecise placing of mats, they probably weren’t all at exactly 7km intervals, but the overall trend, slowing over the marathon, is expected. In fact there’s nothing remarkable in this breakdown: there is no clear indication of significant deterioration among certain age groups. I suspect this was always likely to be lost in the averaging.

Ironman New Zealand 2013: Average Marathon Splits by Finishing Time

An alternative approach, perhaps more realistic than looking at individual age groups for signs of poor performance, would be to consider run pacing by finishing time as in the chart above. I’d wondered if what I saw in the age group top 20s was fast age groupers pushing themselves too hard on a hot day when they were more susceptible to the impact of pacing and nutritional errors, while those over 40 were more prudent in their pacing strategies. If so, then the faster finishers might show more indication of deteriorating performance on the run. Apparently not, if anything the chart shows larger performance degradation in the slower age groups with the most significant change happening mid race (probably an amplification of bad timing mat placement).

As I was already playing with the data and having struck out with all lines of enquiry I thought I’d look at the top level splits and see how the age divisions performed overall. These averages – which I clearly should have started with – show a different picture. In the men’s field the average finish time and splits trend as I would expect with 30-44 year olds being the fastest categories; the women’s field is a little less clear, but again closer to what I’d consider a standard Ironman.

Ironman New Zealand 2013: Average Female Splits by Age Group

Ironman New Zealand 2013: Average Male Splits by Age Group

The pattern I’d observed in the top 20 of each age group doesn’t extend beyond that chart. Averaging over the entire field removes those differences and instead I find a typical Ironman race. To an extent that makes those slower performances seem more anomalous, but my explorations have yet to devise a good means of observing this more accurately. I remain unsatisfied.

But taking steps towards examining race splits in more detail should enable more interesting comparisons between events in the future. Side-by-side we may be able to observe differences in pacing under different conditions. I’ll come back to this when I have more – and more useful – results.

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  • Nadine

    Random about the 7km splits as they should have been pretty even. You know the run has changed? It was 3 laps this year rather than 2. The timing mats were at the turn near the start/finish and then at the top end of the course so the distances should be reasonably accurate. Also T1 and T2 are now in the same place which would be different from when you last raced I think. Try this link for better results:
    You can drill right down into the splits and has the placings at each split. This is good and bad as I have now discovered I went from 7th to 14th in the run rather than just from 10th. Oh well, something to work on 🙂

  • Thanks for the info – yes that’s different to when I did it and should mean the mats are even, or at least consistently misplaced. Actually if the far turn around mat was slightly more than 7K into the loop such that you ran further to reach it than you did to return to the near mat then that would kind of make sense of the changes in pace. But it does makes it all the more odd that lacks the 35K timing split.

    Actually what the timing page you’ve linked to shows is the local timing company had all the splits and details in place, but somehow these have been lost when they’re been sent to the Athlete Tracker. If it weren’t such a pain to do I’d be tempted to write an importer for the data on that page so I had something more complete to look at! Frustrating!

  • Nadine

    Yep, the far turn would be slightly more than 7km as the 21km mark was maybe half a km or so from the mat and aid station at the far end of the course. So by default it would be less than 7km back. Odd that the splits didn’t come up as the timing mat was definitely still in place when I came through on my last lap and they were manually recording numbers as well like they normally do. We were checking live timing at the finish later and nearly missed people finishing as we weren’t expecting them thinking they still had at least 7km to run based on the splits.

  • Anthony Lowes

    Great analysis again Russell – my first time on the course so I can’t compare to previous years but the constant undulation changes on the run really were sapped my legs. Also worth noting I think was a smaller field given the ’11 and ’12 weather and the attraction of the new Asia Pacific Championships in Melbourne with 100 slots for a lot of the fast Aussies who previously would have made the relatively short journey over to Taupo.

  • Thanks Anthony,

    Interesting observation about the attraction of the high-slot Asis Pacific Champs, not something I’d thought of. Makes me wonder about comparing finisher names over the years and seeing if there’s a pattern like you imply, wonder how the Aussie:Kiwi ratio compared this year to previous editions and whether there is a change in athlete choosing to race at New Zealand.