Is Running on the Treadmill the Same as Running Outside?

As the weather turns cooler, then colder, then freezing, some runners begin to opt towards logging miles on a treadmill more frequently. For others, a treadmill can be a safe space to begin their relationship with running in a more controlled, predictable environment. No matter your reason for jumping on a treadmill, it can be a useful tool. Although fundamentally different from running outside, there are ways to optimize your time spent on the “hamster wheel.”

A primary advantage of utilizing a treadmill is that it protects you from both the elements and potentially unsafe running conditions. During the winter months, snow and ice accumulation can make your footing treacherous and potentially dangerous. Even during the summer, moving your workout indoors can help keep you out of heat or humidity that might otherwise negatively affect the quality of your run.

Another positive side effect of treadmill training is the fact that it can help you learn how to pace your run. Many runners perform their long runs too quickly or their intervals too slowly, and setting your pace by the speed of the treadmill belt can help you understand what it feels like to run at prescribed paces.

But let’s not beat around the bush–running on a treadmill is typically boring. Aside from a structured speed workout like a ladder or progression run, miles for the sake of miles in the same place with the same movement can be a bit mind-numbing. In addition, the uniformity of a treadmill does not provide a runner with the type of variation you will experience during your outdoor runs and races.

So what are the most important differences between running outside and training on the treadmill?

• Impact loading. For every action, there is an equal and opposite reaction. The ground reaction force generated by your foot striking the ground with the weight of your body behind it is called impact loading, and that force has to go somewhere. Where does it go? Back up through your body through the kinetic chain. Whatever force you generate on impact is consequently absorbed in quick succession through the feet, ankles, knees, hip and back. The softer, bouncier surface of the treadmill belt is not implicitly a bad thing, and it can even be beneficial in certain situations. However, it will not prepare you for the impact loading experienced on concrete or asphalt surfaces.

The ground reaction forces created during a treadmill workout are significantly less than those generated on harder surfaces outdoors, and ten miles on the treadmill differ to a statistically significant degree than ten miles outside. Many runners become injured when they transition from treadmill training to outdoor workouts, because although they have the fitness to perform the same types of sessions in a different environment, their body is not hardened enough to handle the additional load.

• Better posture. A core component of good running form is known as the forward lean or forward shift. This is a slight forward angle that originates at the ankles, moves your center of mass in front of your base of support and allows you to take advantage of the effects of gravity to help move your body forward through space. By incorporating a forward lean (from the ankles, not the hips!), you also avoid overstriding or “reaching” which takes pressure off your knees by positioning the point of contact directly underneath your hips on a flexed knee.

This proper movement pattern helps better distribute the ground reaction forces we just discussed, and protect the body from repetitive stress discomfort or injury. If you are running on a treadmill, there is a fixed object in front of you and your brain is telling your body to hold back so you don’t run right into it.

A direct result is that poor posture is reinforced because you are running fully upright or even leaning back over your hips slightly. This can be partially compensated for by running on the back half of the treadmill (rather than right up against the console), but even then can cause other issues because now your brain is telling your body to watch out and not fall off the machine.