I had an interesting conversation today with some athletes who do Half Ironman events are are interested in potentially making the change to Ironman events. What they wanted to know was what the difference was in the training. It is a question that I get reasonably often.
Now, this is a question that has numerous different answers and would take a massive blog to answer correctly, however, I thought I would have a crack at giving the short version of the answer.
In short, the difference between Half Ironman training and Ironman training is volume. With Ironman training you do a lot more volume, well duh. The way we coach Ironman at Front Runner is that very little changes in terms of Threshold workouts and Tempo workouts, when a person changes from 70.3 to Ironman, but what does change a lot is that a significant amount of volume is added to the program. For the most part this volume is at lower, more steady intensities and largely comes in the form of long steady rides and runs. Because so much steady volume is added to the program, the proportion of time spent doing higher intensity 'threshold' work decreases.The higher intensity work is still in the program, but it makes up a smaller percentage of the over all program.
The reason for the increases in steady volume is fairly self explanatory, Ironman is a very long event and it requires a lot of strength and fitness to complete. The long steady sessions are how this strength and fitness is built. In the end you have to be able to run a marathon after biking 180km and there are only so many ways of preparing for that. A big part of that preparation is having sufficient volume in your training program. My rule of thumb is that you want to build up to riding 6hrs/200km on some of your long rides and 32km - 35km on some of your long runs. In my view this sort of volume is necessary for you to get to the start line of an Ironman confident that you have done the necessary training to get to the finish line.
So if the low intensity volume is what it is all about, why do we still do high intensity threshold sessions during Ironman preparation. Well the volume is all about building capacity and strength, but the threshold stuff is all about driving improvements. The way I usually explain it is this:
We know that a person can race at between 65% and 80% of their threshold during an Ironman and finish well (where they sit in the 65% to 80% range depends on factors such as their experience, years of training etc). They could push a bit higher than this during the race, but chances are they will suffer for it later in the event. and possibly not finish at all. So if you are limited to 80% at most during the race, how do you go faster? You could race at 85% percent, but chances are that you would bonk on the run and possibly DNF. Another alternative is that you increase your threshold. By increasing your threshold you can still race at 80%, but because you have increased your threshold, the 80% is quicker than it was before. This is important whether you are racing Olympic distance, 70.3 or Ironman, which is why we include threshold training in every program we do.
Despite the differences in the events, the threshold training looks very similar for all our athletes, no matter what the race. This consistency is because, what ever race you are preparing for, your capacity to recover from threshold work stays about the same. If we gave more threshold work to people who are doing Ironman, they wouldn't be able to recovery fully between the sessions and the quality of the sessions would suffer as a result (and they would most likely get hurt). Therefore, these parts of the program stay relatively consistent for all our athletes, while the volume takes a significant step up for our Ironman folks.
And that, in a nutshell, is the difference in training between Ironmand and Half Ironman. Hope it was helpful.