Triathlon Training for a Marathon: My Experience

Disclaimer: I’m not a running/triathlon coach; this is simply an overview of the kind of training that’s worked for me, and what the experts say about low-mileage marathon training.

For the past 4 years, I’ve been triathlon training, but primarily running road races instead of actually doing triathlons (classic me haha).

Why is my training like this? I used to be very injury-prone; my first two marathon training attempts both ended in overuse injuries. I actually wasn’t allowed to run for two months after the second injury. Pretty disheartened, I decided to chase another adventure in the meantime, taking up swimming and biking more frequently. Because of this cross-training base, I dabbled in triathlons the year after my injury–completing two sprint triathlons, and one Olympic distance.

I haven’t done a triathlon since then, but I’ve been triathlon training this whole time. Since the summer of 2015, I’ve done 5 half marathons, 3 marathons, and one 50k. I trained for these races running only 2-3 days a week, and cross-training 3-4 days. I also haven’t sustained any running overuse injuries since then.

So, in this post I’ll be sharing what the experts say about low-mileage marathon training, what my training looks like, and why it works for me.

What Do the Experts Say About Low-Mileage Marathon Training?

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There’s actually an entire book on low-mileage marathon training, and an official training plan exists. The Furman Institute of Running and Scientific Training (FIRST) got the idea for the program when founders Bill Pierce and Scott Murr decided to compete in some triathlons in the 1980s. They realized that they couldn’t just add biking and swimming to their running schedule, or they’d be overloading themselves. So, they reduced their running days from six days to four days.

When they competed in road races, they were surprised to find that their running didn’t slow down despite less mileage. So, they cut their running down further to three days, while still cross-training. They still didn’t lose any running fitness!

This realization led to their Run Less, Run Faster training program and book. This training method involves running no more than three days per week, and two days of high-intensity cross-training. In the training plan, runners will also do tempo runs and speed workouts, and build up to two 20-milers. Runner’s World has a great summary of the low-mileage marathon plan, if you want to learn more before getting your hands on the book.

I’ve never actually read the book myself, but I’d say that my plan was a little more extreme on the cross-training side, since I tended to run only twice a week most weeks, and cross-trained four times. The rest of this post will be a look at my actual training, who might benefit from low-mileage marathon training, and some drawbacks of this type of training (to offer a balanced argument).

Paris Marathon 2019 Training Schedule (Triathlon-Style)

I’ll go over training for my most recent race–I think this is the cycle where things fell into place, and there weren’t any major mishaps like burnout or nagging pains. It’s also where I finally hit my goal of a sub-4 hour marathon! Feel free to check out my Paris Marathon race recap.

I took March as a snapshot since it didn’t involve as much traveling as the other months; it was also my highest mileage month, even if 65 miles (105 km) seems like nothing for marathon training.

To clarify a couple things:

1. My bike sessions were done on a spin bike; a typical workout consisted of a 5 minute warm up, 25 minutes of accelerations/climbs/sprints + corresponding rest, and a 5 minute cool down.

2. Strength training usually meant: bench press, dumbbells, tricep machine, hamstrings, abductors, adductors, squat machine.

3. Yoga was normally home sessions following Yoga with Adriene videos.

4. I usually plan my runs using minutes and not miles, but there are some days I go for a specific distance. I didn’t do a lot of speed work this month, but I tried to disperse some marathon goal pace miles into a handful of runs in February and March. My bike workouts really took the place of running speed workouts, as I did a lot of sprint-style repetitions.

5. I don’t do “bricks,” or back-to-back disciplines in the same day (like biking + running), unless I’m actually training for a triathlon. If I were, I’d probably do 1-2 bricks a week, and do all three disciplines back-to-back at least twice in a training cycle. I think bricks (or even just double-sport days with rest in between) would actually be beneficial for running marathons as lower-impact endurance training. In summer 2015, I did several two-a-days since I was teaching an indoor cycling workshop and training for a sprint tri; the two-a-days and weekend triple bricks were probably a big factor in running my half marathon PR of 1:44:03, especially as I was recovering from injury.

But back to the previous discussion:

I began training for this cycle in late October, giving me just under 6 months. My long runs were every 2-3 weeks, so I had ample time to recover. On the weeks without long runs, my mileage was very low, sometimes as low as 10 miles (16 km) total.

As I was reviewing my training, I also realized how many rest/yoga days I took. There were 5 total days without any form of intentional exercise, and 6 yoga days, which were usually moderate but not strenuous. I think this might be partly due to my recovering ankle–I rolled it while skiing in late February; while I could still run, some of my tendons were especially inflamed after my 20 miler, so I took it easy.

One integral but infrequent part of my training were trail runs with significant elevation gain (1000-1800 feet). I did one each in October, November, and February, and also hiked in April. I think these really helped with strength training, and they made the inclines in the marathon seem much more manageable.

Why Triathlon Training for a Marathon Works for Me 

I mentioned earlier that I used to be injury-prone; since I started triathlon training, I haven’t sustained any major injuries so far (knock on wood!). That said, I also got a gait analysis after my last injury in 2015, where a physical therapist examined my running form and offered me tips to improve efficiency and prevent injury. He also evaluated my lower body strength and searched for muscle imbalances that could lead to injury (I think one of my hips was weaker than the other, as was one of my ankles). The physical therapist gave me a set of strengthening exercises that I still do to this day!

So, my mostly-healthy body despite training for high-intensity events could be thanks to both my improved form, and my low-impact training.

Still, I appreciate all the cross-training because it complements my running. Swimming remains the most challenging discipline for me, and it’s always a good full-body aerobic workout. Biking strengthens my quads, hamstrings, and glutes–perfect for hilly runs. Yoga is de-stressing, teaches me to be more mindful, and stretches out anything that’s tight.

To be honest, I actually haven’t considered any other style of training until recently–it’s simply what I’ve gotten used to. I even end up “craving” cross-training if I haven’t been able to do a certain sport for a spell (usually swimming, as pool access can be trickier while traveling).

In general, I think triathlon-style marathon training could benefit the following people:

1. Athletes recovering from injury.

2. Runners wanting low-mileage/low-impact but high intensity training.

My training is heavily based on disciplines other than running, but you can obviously tailor the “degree” of cross-training to your goals–for instance, increasing running days to 3 times a week and cross-training the other three.

Why Triathlon-Style Marathon Training Might Not be Right for Everyone

I realize that my training is unusual, not very logical, and probably makes a lot of running experts cringe.

The first potential issue is of course the low mileage, which is even lower than the official Run Less, Run Faster plan. For the month of March, my 20-miler was almost 1/3 of my monthly mileage–which really isn’t supposed to happen. Some coaches even say that long runs should only be 20-30% of your weekly mileage (though this seems extreme to me, as you’d have to be doing 67-100 mile weeks to do a 20 mile run). The reasoning behind the rule is that it can be unsafe to attempt longer distances if you don’t have the right training volume. My training has probably been somewhat of an exception since I’m still exercising on the days I don’t run (those training for an Ironman also tend to have longer runs that are a high percentage of their weekly mileage).

That said, many claim that weekly mileage matters in developing speed. Running coach and 2:28 marathoner Josh Sambrook explains that the two most important factors in predicting marathon performance are weekly mileage and pace of those miles. These impact is lessened, however, if you’re aiming for above 3:30 marathons; this is when cross-training and other nuances can make a bigger difference. There’s a cool race predictor tool that Josh introduces in his interview–I found it to be accurate within a couple minutes of my Paris performance when I entered my Barcelona Half Marathon time, my average weekly mileage, and average pace. (He claims that it’s pretty consistent–so even if it’s not totally accurate, you can usually adjust by the difference each time to get an accurate prediction).

On a last note, it’s also clear that such low mileage is not a good idea for races longer than a marathon–I’m already pushing it for marathons, as I’m covering marathon distance only slightly more than twice in my monthly mileage (oops!). I race half marathons more frequently than full marathons, and I think my half marathon PR (1:44:03) is significantly better relative to my marathon PR (3:59:27) because I’m not covering adequate mileage to be as competitive in the full marathon. If you’re running any ultras, so much cross-training is probably not a good idea–I was totally unprepared for the 50k I did last year.

So, What’s Next?

While it seems counterintuitive, running only two days a week for marathon training can work and has worked for me. I can’t recommend such heavy cross-training for everyone, but it can make a huge difference if you’ve suffered from injuries, or if you just want lower-impact training.

Though I’ve been doing triathlon-style training for 4 years now, I’m curious to see how my body will respond to other types of training. I’m actually planning to test higher mileage in upcoming cycles (while still cross-training), especially since running is and has been my primary sport this whole time. I’m a little apprehensive about injury, but I guess I’ll never know what my body can handle if I don’t try.

Do you also cross-train, or have an unusual training schedule? I’d love to hear how it’s worked for you!

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