Marathon vs Triathlon Runners

Marathon Running vs Triathlon Running

Every Triathlete I know is well aware of the need to save your legs for the run portion of a triathlon race. Obviously running after completing 12.4 mile (Sprint Triathlon) to 112 mile (Ironman) bike is far different than doing a run as a standalone activity. When your legs are fresh your performance is always going to be at a higher threshold. So what is the secret to having a good running performance coming off the bike? Let’s dive into this topic on how to save your legs for the run portion of the race and clarify why being a top class runner does not always make you the best runner in a triathlon or ironman.

Why the best runners are not always good Triathletes

If you look through both historical Triathletes, as well as the current champions of the sport, you will see a trend that shows that athletes with a heavy background in running do not fare as well as those with an emphasis in cycling. If you look at the current Ironman World Championship results for 2017, only one of the top 5 finishers has a background in competitive running, none at the collegiate level!

1.    Patrick Lange

2.    Lionel Sanders

3.   David Mcnamee

4.    Sebastian Kienle

5.    James Cunnama

All of the above athletes have a heavy background in competitive cycling, or place heavy emphasis on cycling training. The only exception being that James Cunnama competed in marathon distance runs when he was in his early teens!

So why do these triathletes do so much better coming off the bike and into the run portion of the race than their competitors?

As someone that has been through this first hand many times I can tell you! It has to do with learning how to get the most out of your bike length by being aero, and saving your legs for the run by not burning them out earlier in the race.

How to avoid burning your legs out early in a triathlon

By the time you make it to the run portion of a triathlon your legs have already endured a swim between .5 miles up to 2.4 miles, and a bike between 12.4 miles to 112 miles. That is a lot of punishment on your legs already before you even start your run. With this in mind, it is ideal that you prepare your race accordingly so that you can perform well during the final run. This is why having good swim form and aero positioning are critical to your overall triathlon success.

The swim portion is a much more minor concern than having bike legs before the run. But it is worth touching on briefly. During the swim, you should always emphasis moving your legs from your hip, do not bend at the knee and just “kick”. You should always make sure that you have proper form for each of the strokes you use as well. Believe it or not I find this gets easier with longer distances than shorter ones, since I tend to vary strokes as the distance increases more.

Why the bike proves that triathlon running is far different than running

The bike length of the race is determinant of a good run! It is the reason that good runners do not always make for good triathletes. To put this in perspective the bike length is four times the length of the run portion. So at the max distance of a full Ironman you have to run a marathon, 26.2 miles, but you will be riding the bike for 112 miles in this same race!

A competitive marathon runner is used to competing with a fresh pair of legs from start to finish. But a triathlete has already completed upwards of 114 miles in total before they even start to run. The best marathon runner in the world would crumble if not conditioned for this.

In order to become a triathlon runner you need to look at the big picture and that is turning away from training running heavily and switch to cycling. As mentioned previously, almost all of the top ranking Triathletes have heavy background in cycling. This is not a coincidence.

Race pace during triathlon run

One of the key aspects of a successful triathlon is setting your race pace. The race pace of a triathlon run is different than that of a standard marathon run. If you look at the standings for the 2017 London Marathon, the top finishers had an average race pace of close to 12 mph! But if you look at the top finishers at 2017 Ironman World Championship, the top finishers had an average race pace of about 9 mph. There is no hard reasoning for why this discrepancy lands where it does and frankly it varies from athlete to athlete. Race pacing gets dialed in for triathletes during brick workouts and conditioning your legs to transition from biking to running, which is something that is left out from standard marathon training.

Bike to run transition

Another aspect that differs triathlon running from running in general is the usage of muscle groups and transitioning from one activity to another, as well as learning how to work with your bike and optimizing your aero positioning. When you are riding in an aero biking position you do several things that help preserve your legs of the run length of the race. First off you engage different muscle groups than you would if you were cycling in a more upright position. Aero Cycling engages your quadriceps more than your hamstrings and calves, mostly due to clipless pedals and being able to pull instead of just push on the bike. Second off by being aero you are not fighting the wind and therefore able to save much of your leg strength for running after transition. There are lots of tools you can get to enhance your aero functionality such as Aero Helmets and Aero Wheels as well!


Since there are so many aspects that come into play that dictate the outcome of your run at the end of the race the best thing you can do is make sure to use the Triathlon off-season to your full advantage. Make sure you spend plenty of time in the saddle, increasing the volume of your bike workouts directly correlates to improvements in your run times. Add in a good amount of brick workouts, do this by going for a run immediately following a cycling workout. I tend to try to keep my bike to run ration at the same as it is for race day, so about 4:1 (Bike:Run). Make sure you have a solid strength training plan to help keep your muscles in condition. 

Remember that all aspects of triathlon tie together to ensure your success during a race, just because you have a strong background as a runner does not mean you will instantly be a great triathlon runner. But by following these tips above you can condition your legs and body to get used to transitioning from one activity to another fluidly, and in time, your running and triathlon overall with improve!

About the Author James

Hey there, my name is James and I am the creator and editor of this site. I have been doing Triathlons for a while now and am competing in 70.3 Ironman's as well come this year. I created this site to help those new to the sport and to share my journey with other athletes.

Leave a Comment:

Robert says March 3, 2018

Thanks for the tips, great for a beginner such as I!

    James says March 16, 2018

    Thank you Robert! Appreciate it!

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