If you’ve been around the running community long enough, you’ve heard the great debate on whether treadmill running is better for your joints than running outside. Like any debate, there will always be two sides to it, but from my personal experience and research, I think there’s a clear winner.
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The Cookie Analogy
There is a lot of information out there claiming that treadmill running is better on your joints because of the added cushion from the belt and springs. However, this answer is not taking into account the repetitive motion that is required for running on a treadmill. Imagine your body, especially your joints, like soft balls of cookie dough; if you repeatedly squish them from the top they flatten and eventually begin to get weak and crack. However, if you roll them around in your hand and apply pressure from multiple sides, you can round them into a nice ball of dough that doesn’t crack and break.
This cookie analogy might sound far fetched since our bodies are obviously stronger than cookie dough, but bear with me. When you run outside, even on a relatively flat surface, there is some amount of variation in your foot strike on the ground, but when you run on a treadmill, your feet are impacting an even surface, in the same way, over and over. According to David Jou, D.P.T., “Runner’s knee, shin splints, stress fractures, achilles tendinitis, plantar fasciitis, and muscular imbalances can be exacerbated due to the repetitive nature and decreased variability of the terrain on the treadmill relative to road running.”
The variation in the outdoor running surface is not only easier on your joints because of the variation, but it also actually helps make you stronger because all the small stabilizer muscles are firing and being put to work.
Treadmills As Tools
Treadmills can be a useful tool for speed work, bad weather days, or when you need to run during the dark and don’t feel safe outside. However, the bottom line is that variation is good for your body, so, if you are using a treadmill, just try to alternate between it and the outdoors—preferably on a trail.
