Running outside can be delightful when the conditions are perfect. But if you're trying to make running a daily habit, chances are you'll find yourself on the treadmill at some point. After all, it's only a matter of time before it gets far too hot or cold — or rainy or snowy — for you to feel comfortable outside. When that happens, the treadmill is the perfect climate-controlled alternative, with just one problem: it can really hurt your knees! POPSUGAR spoke to doctors and a certified personal trainer to find out why the treadmill is sometimes harder on your knees than other surfaces. Here's what they had to say.
Why Do My Knees Hurt When I Run on a Treadmill?
"There are a combination of factors that could lead to knee pain when running on a treadmill, including using different biomechanics when running on a treadmill versus outside, as well as using a different stride," Alexis Colvin, MD, an orthopedic sports medicine surgeon at Mount Sinai and chief medical officer for the US Open, told POPSUGAR.
In fact, any knee pain you experience while running is very likely related to your form. If you're experiencing pain in both knees, "[this] is often caused by alignment issues stemming from our foundation: the feet," explained Nelya Lobkova, DPM, a board-certified podiatrist in TriBeCa. "If the feet are not transferring ground reaction forces properly up the chain, alignment is thrown off and knee joint concerns arise." Poor form is often to blame for this chain reaction, Dr. Lobkova added, "especially when on the treadmill." You might also start to lose your form as you grow tired — regardless of the surface you're running on — which can take a toll on your joints.
Even if your form is solid, outdoor surfaces are often more shock-absorbent than a treadmill, helping to reduce joint pain. "Running on the grass and dirt increases the shock absorption from the feet and up the musculoskeletal chain, since the surface has a higher energy return," Dr. Lobkova told POPSUGAR. The same can't be said for pavement, which means that maintaining your form is just as crucial when running on roads or sidewalks as it is when using a treadmill.
However, even pavement has one advantage over a treadmill. Outdoor surfaces generally follow a natural gradient, while a treadmill can stay locked into an incline or decline, which can be "detrimental for the knees," Dr. Lobkova explained. "Outside, whenever there is an incline, there will always be a decline. However, on the treadmill, you control the incline and decline modes, and running too long on a decline can cause a knee overuse injury by over-stressing the knee ligaments and tendons."
If it seems impossible to you that the treadmill could put so much stress your knees, while the outdoors — with all its unexpected bumps and curves — doesn't, you're not alone. But uneven terrain actually helps you to slow down and adapt to your surroundings. "Uneven terrain forces you to focus on form more, naturally decreasing your stride while being mindful of your speed," said Kawan Karadaghi, an NASM- and NESTA-certified personal trainer and corrective exercise specialist.
How Can I Ease the Discomfort in my Knees When Running on a Treadmill?
Just because a treadmill hurts your knees doesn't mean you have to give it up completely. There are several things you can do to ease your discomfort. Karadaghi offered some suggestions:
- If you're equipping your own gym, look for treadmills that have advanced cushioning features, like the Horizon Fitness T101 Treadmill ($650).
- Invest in a foam roller and lightly roll out your quadriceps, IT bands, and calves for 30 seconds to a minute before you run. (Disclaimer: This can be a bit painful if you've never done it, but it's very beneficial.)
- Instead of running on a flat surface, increase the incline on the treadmill to 2 to 3 percent.
- Keeping the treadmill on an incline, start slowly with three- to five-minute runs a few times a week, gradually increasing your time each week.
- Limit your treadmill use to lower-intensity runs, saving your more demanding runs for an indoor track or the outdoors.
Additionally, Dr. Colvin recommends paying close attention to your gait or stride, keeping it as similar to when you're running outside as possible. "Also, try to alternate running with walking instead of constantly running, adding in a warmup and cooldown, and implementing lower body and core strengthening," Dr. Colvin said.
What Should I Do If My Knees Don't Stop Hurting?
If you've seriously injured your knees on a treadmill, the first thing you should do is stop working out and rest. From there, "stretch and foam roll each muscle group for a minimum of one minute per muscle," Karadaghi said. "You can ice knee joints for up to 24 hours after the run if need be. Use ice only if necessary, as it's important to allow your body to use its natural healing abilities."
As soon as you're able, Dr. Lobkova recommends getting a running or gait analysis to determine if you're using the correct running form. "It is important to make sure alignment issues are ruled out," Dr. Lobkova said. "If there are alignment problems, the main solution for the knee pain involves a device that is placed in the shoe to properly align the joints of the kinetic chain." These custom orthotics help keep the foot in a neutral position, at the same time correcting the alignment of the knee joint. "They impact how ground reaction forces hit the knees during running," Dr. Lobkova explained. "Custom orthotics, if made correctly, provide support and reduce pain in the knees."
Of course, you should always check with your doctor prior to staring any new exercise regimen to make sure a pre-existing problem won't be aggravated by your workouts, Dr. Colvin said. Joint pain should never be a side effect of working out, so be proactive and don't ever try to power through the pain. You're better safe than sorry!