I have never been a fan of cross-training, with the possible exception of supplemental strength training. I feel that in order to be the best runner you can be, you should dedicate as much time as possible to actually running. Why bother going for a bike or swimming laps when neither of those activities work the same muscles in the same fashion as running? If you went for a run instead, you would be gaining much more goal-specific fitness.
A few weeks ago, however, I injured my shin and took a week completely off from running and biked instead, and had another week of half running, half biking. Now, you have to understand that riding a bike to me has always been akin to running on a treadmill or having red-hot needles shoved under my fingernails. It is painful, uncomfortable, boring, and evil. It is only through immense will power that I am able to endure such horrific torture, knowing that it builds character.
Much to my surprise, I found that I did not entirely hate biking this time, mostly in part to the fact that my new bike, a Bianchi San Jose single-speed, is actually really nice. It’s not really meant to be a road bike taken on hours-long rides (it’s labeled as an urban commuter bike), but I like it. It’s reasonably comfortable, the gearing is set well (although hills are still a bitch), and the fact that I inherited it from my friend Steve make this a special bike for me. I found I was able to bike for an hour without getting bored, and found myself actually enjoying the ability to cover a lot of ground in that time.
While I was waiting for the shin to recover, I put in some good mileage on the bike, including one day at 23 miles in 90 minutes (remember, I don’t have gears so I can only go ~20mph on downhills, and am lucky to hit 12mph on uphills). The next day, though, I learned an important point. While I was able to bike that long with no ill effects from an aerobic standpoint, I was not prepared to use those muscles or be in the biking position for that long. I wound up overdoing it, and absolutely destroyed my legs after that. My quads were sore, I started to feel sick, and my resting heart rate increased by 20bpm. I actually thought I was getting the flu, but after just two days of not biking, I felt terrific again. Luckily, I was able to resume running shortly thereafter, and I am back to doing what I know and love.
During my time confined to the bike, though, I realized that biking really is a great way to cross-train, or put in some additional work. It is completely zero-impact, so it is entirely possible, and not entirely harmful, to log many hours on the bike. Even the most elite runners find it difficult or dangerous to run more than two hours a day because it is such a high-impact activity. But even age-grouper triathletes can log as many as 8 hours of biking in a day. That is a lot of aerobic fitness with not much wear and tear! Plus, most triathletes tend to be terrific runners, despite only running a third to half of the mileage. That right there shows you how much fitness they gain from the biking and swimming.
While I can’t see myself becoming a regular biker, I do foresee myself supplementing running with biking a bit here and there. It is an activity that Ashlie and I can both partake in without one of us feeling like we are slowing the other down, and since it is not my main focus, I don’t care about getting a good workout in on the bike. Furthermore, biking for an hour after running is another 60 minutes of cardio without the impact of running. So it is entirely possible for me to get even fitter by adding in a few hours of biking a week.
While I had always considered cross training a necessary evil intended solely for injury-prone runners, I can see now how it could be beneficial even to healthy runners. Biking or swimming (or weight lifting) will never replace running in terms of producing the most bang for the buck, but they can be useful supplemental training tools. I still am first and foremost a runner, but don’t be surprised to see me biking here and there in the future!