It takes all the running you can do, to keep in the same place. If you want to get somewhere else, you must run at least twice as fast as that!
― The Red Queen
I don’t know if Lewis Carroll ever set foot on a treadmill, but he got one thing right: all the running in the world gets you nowhere on those things! I’ve learnt to enjoy running outside in the past 4 years. It helps me take my mind off things and think things through. Even though I tend to run always around the same corners of town, I enjoy sightseeing and people watching while running. Ever since (and for as long as I can remember before that), I’ve never enjoyed running on a treadmill.
On a treadmill, I always need to be focussed on what I’m doing, or I risk running to much forward or deviate to one side and hit the machine itself. I would concede it might be a very “me” issue, but it means I can’t switch off or focus on inner problems. The impact on the joints feels different than when running on the concrete: it is softer than concrete and yet harder than grass. On top of that, I have to think about my pace (which is “imposed” by the machine; if I want to slow down or accelerate, I need to actively tell the treadmill to do so). I also need to think about my position on the treadmill, think about breathing, and pretend I’m enjoying the whole process. Call me limited, it tends to be too much, and I hate it. I can’t find refuge into my head, go to my happy place, or enjoy my music because I risk ending up falling off the thing.
On top of that, I don’t really get the fuss about running to remain exactly where you are. I have a bit of a similar issue with elliptical and stationary bikes. With those 2, I can at least switch off without risking being ejected off them. The impact on the joints is definitely better than when running, either outside or on the treadmill, but still – we ain’t going anywhere! And all 3 machines (treadmill, elliptical bike, and stationary bike) are brain tricksters. I’m not talking about the fact that exercising will trigger the release of endorphins in your brain (the feel-good hormone). No, those machines will temporally alter our perceptual calibration. Let me explain.
As we walk around, we learn unconsciously to associate a certain pace with a certain way to perceive the world, or optic flow. When you walk you see the world moving past at a predictable rate that differ from when you run, cycle, or drive. We learn to expect a certain optic flow with a given speed. If you start seeing the landscape through the window of a train as you do when walking, you would feel disoriented as it violates the expectation you have. It would take your brain a few moments to associate this new way of seeing things with driving speed, and not walking speed. So far so good?
On a treadmill, or any of the machines on which you move and yet go nowhere, our brain comes to expect that to stay still it has to move at a certain speed (the one you have on the machine). The brain associates the no movement of the world around (zero optic flow) with locomotor activity (i.e., walking, running, cycling). Hence the dizziness and cotton-leg sensation you can have when getting off the machines.
It is the manifestation of the recalibration of your brain.
One way to show it is to blindfold someone who’s just been on a treadmill (scientific studies seem to focus on treadmill…) and ask them to walk or run on the spot: the person ends up moving forward without realising it. Everything goes back to normal once the blindfold is off and the brain can recalibrate. A recent study added to the demonstration by introducing virtual reality headsets. Participants ran on the treadmill while wearing the headsets, which displayed streets passing by as they walked. They showed that the brain didn’t need to recalibrate anymore and participants didn’t drift forward if blindfolded once off the treadmill.
This is but one example of all the unconscious work our brain has to do to allow us to navigate the world and process information around us. The virtual reality or screens showing moving landscapes might be a good thing for training on those stationary machines, as it removes the need for brain recalibration. I don’t know if the longer you train on a treadmill without optic flow, the longer it takes to recalibrate, but it might be safe to assume that the least we mess up with the brain, the better it is for us.
Let me finish on a historical note: treadmill have been around since the 1st century AD. They weren’t used for fitness back then, but to harness mechanical power. This power could in turn operate some types of mills, to grind grain or pump water for example. The infinite staircases (those step machines that make you climb in place) were another type of treadmill used to power bigger structures. However, in the 19th century, treadmills and infinite staircases were introduced in prison and used for punishment, until some US researcher decided to commercialise them for fitness benefits in the early 20th century. From torture to fitness, it is a fine line…
On that note, time to go for a run!
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