Is running really bad for your knees?

Whether you're a runner or not, you've probably heard someone say running is bad for your knees. Maybe you shrugged it off; maybe you believed it. As a former cross-country runner and casual half-marathoner, I hear it all the time, especially from my dad, who I'm sure has my best interests at heart (but, bless his heart, doesn't know anything about running). 

"All that running's going to do a number on your knees. You'll see when you're old."

After years of my feet pounding the pavement, I don't have a lick of knee pain and I don't expect to. Yet I'm always told it'll happen. 

I started to wonder if this is just some long-standing conventional wisdom people accept as the indisputable truth -- like "Eggs are bad for you" or "Drink eight glasses of water a day."  

The bulk of research available on the topic suggests my inkling is correct: Running isn't necessarily responsible for bad knees. 

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The myth: Running is bad for your knees

Quite the contrary -- with a couple of caveats that I'll get to in a minute. Studies routinely show that recreational and competitive runners have lower rates of knee osteoarthritis than people who don't exercise at all, and that running doesn't seem to be a risk factor for knee osteoarthritis. This is true even for older runners who have a history of long-distance running. 

What's more, a 21-year-long study concluded that a running habit correlates with an overall reduced risk of disability later in life. 

If you already have bad knees, this changes -- somewhat. It's clearly not a good idea to pound out 10 miles if you have existing knee arthritis or another knee issue. However, research in this area is promising, too. One study found running to decrease inflammation in people who already had osteoarthritis in at least one knee, while another suggests running can improve knee health markers in people who start a training program with knee damage. 

For those with existing knee issues, working with a professional running coach or physical therapist (and following a training program designed for you) is the safest way to run.

Read more: Treadmill vs. running outside: The pros and cons of each

The truth: Running with bad form is bad for your knees 

Running itself isn't bad for your knees, but running with poor technique can certainly harm them. 

"Anything overdone or done incorrectly could be harmful," says Steve Stonehouse, a personal trainer, certified run coach and director of education for STRIDE. 

"In many cases, there is a breakdown in the mechanics, causing a lack of efficiency and abnormal wear [on the joints]," Stonehouse says. The wrong shoes and certain terrain can always cause problems, as can technique issues. 

Common running technique flaws include: 

• Poor posture, especially hunching during runs
• Titled pelvis, especially an anterior pelvic tilt that causes your lower back to hyperextend 
• Excessive foot pronation or supination
• Heel striking, particularly when in combination with overstriding

Some of these form issues can be remedied with conditioning, while others may be linked to your physical makeup, Stonehouse says. If any of these running form issues apply to you, "then, yes, you're going to have a tougher time," Stonehouse explains. Still, he promises, "You can run without injury; you just have to focus on proper form and mechanics."

For my weightlifters out there, compare this to deadlifting. You probably hate when people tell you deadlifting is bad for your back. In reality, the deadlift is one of the best movements for strengthening your back -- but deadlifting with bad form is a disaster for your back. 

The question: Could running actually be good for your knees?

We've cleared up the myth that running is bad for your knees. So now the question is whether running is just neutral or if it's actually good for your knees. Do your knees simply survive running, or do they thrive because of running? 

A 2020 study says running might actually be good for your knees. In the study, computer modeling confirms that running places more stress on the knees than walking -- but it also suggests that the cartilage in knees is more malleable and responsive than previously thought, and that it might respond to the impact of running by bulking up and strengthening. 

This isn't the first study to suggest as much. Back in 2014, researchers pondered whether the increased stride length of running (and thus having less overall contact with the ground) versus walking is the reason behind low rates of osteoarthritis in runners.

Obviously, computer models are theoretical. This study doesn't tell us anything about how cartilage changes and grows without a blood supply, nor does it account for how genetics, body size, footwear and other factors affect the knees when running. 

But it does provide a potential answer to the question: How is it that millions of people run long-distance races every year and don't suffer injury after injury?  

Should you stop running if you have knee pain? 

You don't necessarily need to stop running if you feel knee pain, Stonehouse says. He suggests first checking to make sure you're wearing the right running shoes for your foot anatomy and running style. If you're unsure, you may want to visit a running shoe store that can perform a gait analysis and match you with a proper running shoe. 

After confirming that your running gear is right for you, you can try stretching and cross-training exercises to help alleviate knee pain. "The root cause of your pain would direct what the specific flexibility and strengthening exercises need to be," Stonehouse says. Additionally, mixing in walk/run intervals can offset some of the impact of running. 

But, as always, if you have persistent or severe pain, consult with a professional. A physical therapist is the best health care provider to help with running-related pain.