How to nail an Ironman run…don’t nail the Ironman bike.

Edited 16/12/2015 – The athlete this article refers to was awarded ‘Athlete of the Week’ on the IM Talk Podcast this week.  How cool!  Here’s the link to their podcast.

We all know how important the Ironman run is. It is here that the race is defined. It the part of the day that hopes and dreams can be solidified or lost for good. Of course you are going to make the finish, but will you do it in the time you hope, with all your marbles intact and ready to come back fired up to strike in the next race. For so many, infact probably the majority, the run leg of an Ironman becomes a point in the race where you are just hanging on for survival. Very few athletes are able to press on and build their effort through the run leg, and the reality is that even the fastest runners on the day are slowing down as each KM goes by. The athlete who slows down the least is the one who runs the best, and this may also be the person who runs the best when they are feeling the worst.

But the success of your Ironman run leg is determined by what you were doing to yourself many hours earlier, when you were on the bike leg. And the first few KM’s are as important as the closing part of the bike leg. Making a conscious effort to stick to a predetermined intensity, and being disciplined enough to do just this is the recipe to Ironman run success. A power meter makes this job so much easier.  It can be done with an understanding of your perceived effort and Heart Rate, and a bit of practice in the lead up to an event, but the power meter makes it easier to manage and the post-race analysis of the bike leg a lot more interesting and fun.

It is a well known assumption that a TSS score of 280 points is the recipe to Ironman success. Exceed this and you run the risk that you pushed too hard, go under it too much and you are probably not pushing hard enough and will take too long than you need to on the bike. Taking this knowledge forward you can very easily prepare a power plan for an Ironman bike leg. But your method of getting to this 280 point value is as important as simply achieving it. You don’t want to get there having surged over and under your target watts value over the course of the ride, so a power variability of 3-5% (1.03-1.05) is about the target to hit, and less variability is better again. A greater variable effort is more fatiguing than an even steady output. The athlete who can keep variability low is more focused on the process of racing rather than external factors such as course, conditions, other athletes. This is where the benefits will be found later in the run.

We also know that coming off an Ironman bike leg at about 71-73% of FTP range is ideal for most well trained age group athletes. This is assuming their FTP has been accurately calculated, and they have trained at such intensities.

The other thing is to make sure fueling is consistent and the athlete has the right amount going in for the work they are doing. This helps to deliver the athlete to the start of the run with the least amount of physiological fatigue. The success of this can be determined by viewing the decoupling measure (pw:hr) over the course of the ride. Any thing under 5% can be considered a successful delivery of effort and a very efficient athlete. The amount of decoupling is also dependant on power variability, so it is important to get that mix right.

I recently had an athlete achieve their IM run goal of going under 4hrs. They went 3:58, so that box was ticked. There was a bit of a wobble during the mid-portion of the race (who doesn’t have that happen, but they pulled it back together and finished strong) owing to their fantastic aerobic capacity and strong-mindedness. During the process of getting this run time they took 40mins off their best IM bike split, and took nearly 60mins off their previous best IM time….so it was a very successful day. For me the greatest success came in the way the bike leg was managed.


Have a look at this pic of their bike leg summary. You will see all the key milestones were reached – 285TSS, 2.38% decoupling, only 1% variability (can’t get much better than that over 180km), 72% of FTP. I can tell you that this athlete is one of the most meticulous I have worked with, and this is reflected in the way the bike plan was adhered to, especially on a day the conditions played a major role, and a lot of people blew their races with poorly managed performances on the bike.

This didn’t come by mistake. We had discussed at length as to what would be the optimal power plan for the race, and even had a few scenarios incase things out of our control caused a sudden change in plans. With this athlete being on our Custom Coaching Data+ plan we utilised some online power prediction software, and changed the plan as the weather forecast changed in the days leading up to the race. A bike vs car crash 2 weeks prior didn’t even have any significant negative effect, in fact it probably even helped the taper as there was no training for a few days post accident.  We even fine tuned the training sessions in the few days before the event to make sure race-day was hit with the optimal balance of fitness, freshness and mental readiness.

It was awesome for me to see these goals get achieved, and I’m looking forward for what might come next….after a well deserved break from training for starters as this has been a long focused campaign.

For more information on our Custom Coaching and Custom Coaching Data+ services please email or check our website you can also find out some information on our subscription coaching memberships, and the training plans you will gain access to here. We have a free 14 day trial membership for you to take some time to check it out.

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