Cross-Training

How Close Can Cross-Training Take You to Your Running Goals?

What percentage of your running volume can you replace with other types of exercise and not have to adjust your goals?

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It is likely that no runner in Corral A of Wave 1 at the start of the 2019 Boston Marathon had done less running in the preceding several months than I had. For starters, I was just four weeks away from competing in an Ironman triathlon, hence less singularly focused on running than I might otherwise have been, with considerable training time spent on the bike and in the pool. On top of that, my run training hadn’t been going well. Hampered by nagging hip pain that had only recently begun to abate, I’d averaged less than 30 miles per week in the last few weeks and done virtually zero fast running.

My goal for Boston was to run as fast as I could without reaggravating my hip or compromising my ability to dive right back into Ironman preparation when I returned home to California. This process-focused goal got me to the finish line in 2:54:08, which, although not my fastest marathon, was faster than I’d run in any of my three prior tilts with Boston.

I share this story often with the runners I coach who are skeptical about the potential for a cross-training heavy training program to deliver the performances they seek in running events. Most runners who lack extensive cross-training experience doubt its effectiveness, which is completely understandable. I mean, how the heck is riding a bike or using an elliptical machine supposed to make you a better runner?

Some Running, Lots of Other Stuff

I’m sure I would have the same doubts myself if I did not have the vast cross-training experience I’ve acquired both as a triathlete and as an injury-prone runner who refuses to allow a propensity for tendon breakdowns to affect his competitive ambitions. My performance at the 2019 Boston Marathon only confirmed what I already knew in this regard. Three years earlier, I’d won a 50K trial race on a training program consisting of just three to four runs per week and three times that amount of cross-training. And way back in 2002, I managed to put up a respectable 3:23:39 marathon split at Ironman Wisconsin after training through another hip injury that kept me from doing any running until six weeks before race day.

Granted, I’m just one guy, but unless there is something exceptional about my physiology, these experiences prove that any runner can achieve close to 100% of their performance potential in running events with a modest amount of run training and a whole mess of cross-training.

Still, it doesn’t hurt to look at other examples. Consider Morgan Pearson, an American professional triathlete who won the 2020 Michigan Pro Half Marathon against a field of elite runners, recording a superb time of 1:02:15 on a challenging course. The 60 to 65 miles Pearson runs in a typical week might be a lot for a triathlete, but compare that to the 100-plus-mile weeks the pure runners he defeated log on the regular. You can be sure that the 20-plus weekly hours Pearson devotes to swimming and cycling made a significant contribution to his performance in Michigan.

Not all of the evidence supporting the value of high-volume cross-training is anecdotal; there’s also some science. In a 1998 study, for example, Mick Flynn and colleagues at Purdue University added either three extra runs or three stationary bike workouts to the training programs of 20 runners for a period of six weeks. All of the runners completed a 5 km time trial before this period of modified training and again afterward. Both the running-only group and the cross-training group improved their times by an average of 2.5%.

Matt Fitzgerald in 2019 Boston Marathon
Matt Fitzgerald in the 2019 Boston Marathon Photo: courtesy Matt Fitzgerald

How Much Run in the Mix at Minimum?

It’s clear that you can add some cross-training in the mix and stay race fit, but how much training can runners replace with alternate activities before their running performance begins to suffer? Note that even with the addition of bicycling, the runners in the above study were doing less than a third of their overall training in the form of cross-training—a far cry from the two-thirds I’ve had success with.

One thing is certain: Three-thirds cross-training is a bridge too far! A 2012 study by David Honea of Appalachian State University found that 3000m time trial performance decreased in high school runners who replaced all of their running with cross-training for five weeks, whereas times improved in controls who continued running.

Speaking as a coach, not as a scientist, I believe that three runs per week is the minimum frequency of running required to avoid lowering performance expectations on a combined running/cross-training regimen. As for how much cross-training to do on top of that, I say the more, the better.

There is a law of diminishing returns, of course, and each athlete has their own personal limit, but the beauty of low- and nonimpact forms of cross-training is that they carry a lower risk of injury than running does. Hence, on a cross-training heavy training regimen, you’re likely to be able to do as much as your body benefits from, which is probably more than you think. Amateur long-distance triathletes with average talent routinely tolerate weekly training volumes in the 12- to 16-hour range. You may not want to spend that much time working out, but you probably could.

Keep it Similar

Something to keep in mind, should you choose to go down this path, is that not all cross-training is equal. The more similar to running your chosen cross-training modality is, the more effectively the fitness you develop within it will transfer over to running.

This was shown in a 1995 study led by Carl Foster of the Milwaukee Heart Institute. For eight weeks, 30 runners increased their training volume either through additional running or through swimming, an upper-body dominant, non-weight-bearing activity that is highly dissimilar to running. Both groups improved their 5K performance more than controls who continued with their normal run training, but the swim group improved only half as much as those who ran more. Compare these results to those of the previously described study in which the addition of cycling (a legs-dominant, semi-weight-bearing activity) to a running program improved performance by the same amount as extra running.

Matt Fitzgerald training on bike
Matt Fitzgerald training on the bike. Photo: courtesy Matt Fitzgerald

My personal favorite cross-training activities are uphill treadmill walking (harder than you think), outdoor elliptical biking (way more fun than indoor elliptical running), and cycling. As long as you’re running enough to establish the repetitive impact tolerance and develop the biomechanical efficiency you need for your next running event, the fitness you develop through any of these activities will transfer over to your running quite well.

Are they truly just as good as extra running, though?

There was a time when I thought maybe they were. But in 2017, when I was 46 years old, I joined the Flagstaff-based NAZ Elite team and trained as a “fake professional runner” for an entire summer, running 10 or more times per week for the first time in a while and cross-training minimally. Although my body barely held up under these rigors, at the end of the summer I broke a nine-year-old marathon PR, eclipsing by two minutes a time I hadn’t come within eight minutes of matching since I set it. (Indeed, this was the performance that earned me a spot in Corral A of Wave 1 at the 2019 Boston Marathon.)

So no, for runners, nothing beats running. The point I’m making here is that high-volume cross-training is far better than nothing, and may take you to higher performances than you expect.