Running 50 marathons in 50 days; running across America in 42 days: There are some feats of endurance running that make your jaw drop. But would these stories have the same impact if the same distances were run on a treadmill? Probably not (unless it was made into a music video).
So why do we see treadmill running as inferior? Aside from the obvious benefit of outdoor ambience — fresh air, trees, a general sense of being one with/conquering nature — is there any benefit to running outdoors instead of running on the human equivalent of a hamster wheel?
On the one hand, with a treadmill, the belt is moving under you and there’s no wind resistance for your body to counter, so yes, it is in fact easier than running outdoors. The difference isn’t that great, though: Research suggests that simply setting the treadmill to a 1 percent incline accurately simulates the energy costs of outdoor running. Corroborating research has shown that VO2 max — the maximum amount of oxygen your body can take in and actually utilize at maximum exertion, which directly affects your aerobic endurance level — is the same when running on a treadmill as running outside.
Of course, one of the unique benefits of a treadmill is the ability to try to match the terrain of the race you’re training for. This brings its own set of problems, though: When you’re running on a treadmill, it’s easy to just lock into a target pace. Unfortunately, this doesn’t teach you how to properly find and maintain pace on your own, meaning that when race day comes, you won’t have developed that fine sense of pacing that’s crucial to running a negative split and finishing strong. (It may make you less able to outrun a surprise bear attack as well — just something to consider.)
The treadmill can also be worse for you psychologically. When you’re doing a tough run outside, you can “feel” the finish line getting closer and have a more natural sense of the distance remaining. When you’re on a treadmill, your mind can’t visualize the finish line as well. This means that, when the pace gets tough, you may find it harder to push yourself that extra bit required to get the race run.
All of this may be a secondary consideration if you’re hoping to avoid injury by running on a treadmill. But research also suggests that injury biomechanics are the same for running on a treadmill and running outside. So if you’re worried that you’re more likely to screw up your knees by running outdoors, rest assured, the science says otherwise (just watch out for potholes and other potential obstacles).
Much of the same cost-benefit analysis holds true for the elliptical, but not, it seems, for rowing or cycling machines. The average “I want to do cardio but I don’t like running” weekend gym-goer will have a much harder time getting their heart rate as high on a real bike or in a real boat, as they’d struggle with pedaling or rowing fast enough while keeping their balance to get the same muscle workout. (This obviously isn’t true of professional rowers/cyclists.)
So for all you weekend warriors who insist that there’s no replacement for real-world terrain or that “Outdoor running is the only running,” it turns out that, okay, you do win this argument. But only by a nose.