As you well know, the Ironman world Championships take place every October. The history of Ironman is a spectacular story. Many of us have heard this story, but let’s tell it again anyway. In 1978, during the awards ceremony for a Hawaii running race, a debate ensues among competitors about who is more fit, runners, swimmers, or cyclists. One of the participants, Navy Commander John Collins and his wife Judy, dream up a race to settle the argument. They propose combining three existing races together, to be completed in succession: the Waikiki Roughwater Swim (2.4 miles), the Around-Oahu Bike Race (112 miles, originally a two-day event) and the Honolulu Marathon (26.2 miles). Whoever finishes first, they would call Ironman. Fifteen men participate in the initial event held on February 18; 12 complete the race, led by the first Ironman, Gordon Haller. His winning time: 11 hours, 46 minutes and 58 seconds. As a side note, I would argue that the success of Ironman has been the primary source of growth behind the expansion of triathlon in general, at all triathlon distances. But that is another topic.

Over 20 years later, science may have taken some of the suspense out of the bet that changed the athletic world. Who is more fit? Swimmers, bikers, or runners? Before I share with you the data, we have to come to a consensus on what fit and fitness mean.

In reality, measuring fitness is all relative to the sport you are observing. As triathletes, we generally think of ourselves as fit. However, if we were to enter a shotput competition against athletes who regularly shotput, we would likely be significantly outperformed. On the other hand, Shaquile O’neil is an awesome basketball player, and his fitness in that discipline is outstanding, but I’d put money on the fact if we raced tomorrow, I could probably cross the finish line before him in an Ironman.

So, as triathletes, we can only really determine fitness within our own sphere. I would propose to you then, that in the realm of triathlon, fitness is defined by cardiorespiratory and muscular endurance. Or, in simpler terms, how long and how hard you can exercise. This definition of fitness is backed almost unanimously by researchers, who use measures of cardiorespiratory endurance to categorize levels of fitness in their test subject. For example, when I talked about the research on caffeine, I mentioned that the researchers used competitive runners. How did they determine what “competitive” was? They based it on the subject’s high cardiorespiratory endurance. Stay with me here, there is a resolution to all this background I’m giving you. The measurement used to determine cardiorespiratory endurance is a term called maximal oxygen uptake, or more commonly called VO2max. Now, I could spend a whole post on V02 max, and maybe I should, but I don’t have time today. Let me just say that in the world of physiology, a high V02max is considered the best measurement of cardiorespiratory endurance, which we have defined as fitness in the context of triathlon.

So with that background, is it possible to settle the original Ironman bet regarding which type of athlete is the most fit, using measurement techniques that did not exists 28 years ago? If we accept that fitness can be measured best by cardiorespiratory endurance, I suggest that we can.

I have the results of VO2max measurements from athletes in 21 different sports, not only including swimmers, bikers, and runners, but including sports such as wrestling, canoeing, soccer and ice hockey. See, I love this stuff. My left-brained mind loves to categorize things, and order things, this stuff is right up my alley. Anyway, the results are as follows. Between swimmers, bikers, and runners, the athletes with the highest average V02max are runners. Followed closely by cyclists, and then swimmers. Overall, the athletes with the lowest V02max were softball and baseball players, who came behind horse jockeys and ski jumpers. Of the 21 sports researched, cross country skiers had the overall highest V02max. Makes me want to consider x-country skiing as part of my off-season training. One interesting note. Although runners had a higher VO2max, cyclist had bigger hearts.

David Warden is a 3-time USAT All American and Elite Coach with Joe Friel's TrainingBible coaching. His work has been published in Triathlete and USA Triathlon Life magazines. He is the former Vice-Chair of the USAT Rocky Mountain Region, and the host and producer of the #1 triathlon podcast, Tri Talk and part owner of  www.powertri.com.