There is a consistent pattern in my coaching of endurance athletes that I wasn’t conscious of until quite recently. When I coach amateur runners for marathons, more often than not I increase their training volume relative to their past habits. But when I coach amateur triathletes for Ironman events, quite often I have them train less than they have in the past. Upon reflection, I recognize that I do so for the obvious reason: I see a lot of marathon runners who, in my assessment, can both tolerate and benefit from training more, and I see a lot of Ironman triathletes who, I believe, would feel better, recover better, and ultimately perform better if they trained less.
Obviously, the two events, marathon and Ironman, are far from equal. In the former, you run 26.2 miles. In the later, you also run 26.2 miles—after swimming 2.4 miles in open water and bicycling 112 miles. Because an Ironman is significantly bigger and more challenging than a marathon, it selects for a different population of participants. Generally speaking, Ironman participants are willing to invest a lot more time and effort into training than are marathon participants. Not infrequently, I encounter runners who want to qualify for Boston yet balk at the idea of running more than four or five times a week. No less frequently, I encounter triathletes whose marriage is under stress because they habitually spend all of Saturday riding their bike instead of taking the family to the county fair.
I don’t mean to paint with too broad a brushstroke. There’s plenty of overlap between the two populations. Many a marathon runner signs up for a marathon in pursuit of a fresh challenge. Typically, when an athlete makes this leap, they increase their training volume, which is sensible. Indeed, they more or less have to train more, given the three-discipline nature of triathlon. But they are also able to training more, as both swimming and cycling are less stressful physiologically than running is. Ten hours per week of balanced triathlon training are not as hard on the body as 10 hours per week of running.
The mistake that a lot of triathletes make, though, is assuming they will get the greatest possible benefit from the highest volume of training they are willing to take on. If 14 hours per week doesn’t get them to Kona, they try 16 hours, taking it as a given that the increase will yield improvement. If 16 hours per week doesn’t get them to Kona, they try 18 hours, and so on. Experience has taught me that this approach is flawed. I firmly believe that athletes should feel pretty good most of the time throughout the training process, and in case after case, triathletes I work with feel better when I reduce their training volume from the level they had tried to maintain before I got my hands on them.
And wouldn’t you know it, a new study in the journal Physiology & Behavior offers empirical validation of my experience. Ninety-nine triathletes completed a survey comprising questions about training, experience, anthropometric characteristics, and other factors prior to their competing in an Ironman triathlon. The respondents were statistically separated into three groups: those who trained less than 14 hours per week, those who trained between 14 and 20 hours per week, and those who trained more than 20 hours per week. Check out the average finish times for members of the three groups:
That’s right: No differences! What does this mean? A scientist would be careful topping out that it could mean any of a number of things. But I’m not a scientist, so I’ll go ahead and tell you what it means: It means that 14 hours of training per week, give or take, is the optimal amount for most amateur triathletes. In fact, the scientists who conducted this study came to the same conclusion, noting that subjects who reported unintentional weight loss, lack of energy, and decreasing performance before the race recorded significantly slower finishing times.
Interestingly, the authors also found that more experienced triathletes achieved faster Ironman times regardless of how much they trained. One possible explanation for this finding is that, through trial and error, these athletes had found their individual sweet spots for training volume. That was certainly the case for me when I prepared for Ironman Santa Rosa in 2019. Although I had done only one prior Ironman, I had been training for and competing in endurance events of various kinds for many years, and I knew my body well. Based on this knowledge, I maintained a consistent training volume of 14-18 hours per week, with only one week exceeding 20 hours (and just barely). I felt consistently good throughout the process, and upon completing the race and looked back, I felt confident that I would not have fared any better if I’d trained more.
I’m not suggesting that the above numbers represent the sweet sport for all recreational triathletes during Ironman training, though I would speculate that they fall close to the median. The take-home lesson of this article isn’t that recreational triathletes should never bother training more than 14 hours per week during Ironman prep. Rather, it’s that you should be wary of training at too high a volume, as many triathletes appear to do. You will perform best in your Ironman events if you train at the highest volume at which you consistently feel good, whatever that number may be.