Is Treadmill Running Bad for Your Knees?

Preface

I haven’t ever hurt myself or got knee pain from running on a treadmill.  I know a lot of people who scorn the treadmill as bad for your knees.  This post will discuss how I run on the treadmill.  It will also discuss how I see other people running on the treadmill as well as differences in gait on a treadmill compared to running not on a treadmill in the real world.

Another thing to mention before I get started is that I HAVE hurt myself running multiple times on flat ground outside.  There is gravel, uneven ground, tree roots, broken glass bottles, hard pavement, cars not looking for you, pollution, traffic lights, and DOWNHILL.

Downhill means even larger ground impact forces due to gravity because you have longer time for gravity to accelerate your feet into the ground due to different ground heights from when your foot leaves the ground to when it hits the ground again.

Don’t EVEN get me started about listening to music while running outside.  If you get hit by a car, that’s your fault!  Trail running might make that safer, I guess.

They still are comfortable and don’t hurt my feet in spite of the wear and tear.

Suffice it to say, I have not sprained my ankle yet from running outside (trampoline is another story) despite all these terrain hazards, which also are part of the fun of running outside.  You get in touch with your primal self to avoid obstacles, which is a challenge in itself and a break from the gym monotony of running on the treadmill.

However, most of the time I run to accomplish whatever metabolic cardiovascular goal I have set for myself that week, and zoning out while running outside has been dangerous for me in the past.

The whole next two paragraphs are to get endurance athlete elitest jerks off my back about running on a treadmill.  This article is mostly for those who complain that running on a treadmill is bad for your knees.  If you are new to exercise, hang on, because we will get to the good stuff.

My speed will be either 7.1 if I’m doing a “moderate” cardio day, 8.5-9.0 if I’m doing an “intense” cardio day, and as fast as it can go if I am doing sprints (12.0 at my gym).

The purpose of me mentioning my speed is merely to show that I am not an amateur runner and have an above average VO2max at 63 mL/kg/min, measured during grad school on two occasions with the same result.  I no longer consider myself an endurance athlete compared to my training as a competitive swimmer from age 11-19, but I still do cardio now.

Now the good stuff

I turn the incline up to 3.5 when running.  This goes for all speeds.  My minimum incline is 3.5.  The reasoning for this is that walking uphill is less gravitational force impact on your knees per step compared to walking on zero incline.

I personally don’t find lower inclines to be enough for me, but anything above 0.0 incline should be less impact force on your joints.  If you think 3.5 is too much, start with more incline than 0.0, even if that is 0.5.

The incline setting means that at 3.5, I get a vertical ascent of 3.5 feet for every 100 feet I walk horizontally.  It is a 3.5 percent incline.  It’s really not that big of a deal in terms of difficulty, but it makes a huge difference on ground impact forces per step taken.  Multiply the number of steps you would take on the treadmill, and you are saving a lot of force on your knees.

Most gym treadmills will have some cushion or give.  This should lessen the force on your joints even more.

Last, I land heel to toe.  When my heel lands, I am already pulling backward with my hamstrings and gluts.  I am not pushing into the ground forward through my quadriceps.

If you are pushing with your quadriceps, that’s putting an acute forward force on your knee while the belt is going backwards.  It’s basically going to aggravate those ligaments in your knee that resist shear forces.  That’s a great way to give yourself knee pain.

I think it is very important to emphasize hamstring contraction to pull your foot back ASAP when on a treadmill because the belt is moving backward.  When you are on flat ground outside, you have more time to contract that hamstring since the ground isn’t moving and you are more aware of the ground.  Don’t let the belt do the work for you either.

Finally, I don’t land heavy.  If you can hear loud thuds when you run (you’re stomping), you’re releasing a lot of sound energy from impact forces.  It is inefficient use of force.  It’s probably not good for you.  It’s also annoying for everyone else at the gym.

It is a sign you are half-assing your gait and landing heavy because it’s too much effort for you to protect your knee and hip joints with the muscles surrounding them to cushion each footfall.  If you are this person, no shade, but you probably don’t know you’re doing it or realize it is tough on your body.

No Shade

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