Stressed about knee stress?

Hiking in the mountains.

Stressed about knee stress?

You should be!

For the last few decades, we’ve had it drilled into our heads that we should minimize impact to our joints in order to preserve them. Pain under the kneecap, after all, is the most common complaint among physically active children and adults seeking medical treatment in sports medicine clinics, accounting for 62% of all knee injuries, according to one study.1

This condition, known as patellofemoral pain syndrome (PFPS) in the medical field, accounts for 57% of all knee problems in runners,2 and has been dubbed “runner’s knee.”

So how do we run (bike, ski, hike) and still protect our knees? Is there really such a thing as a "low impact" or "zero impact" workout?

Well, yes. And no.

The Impact of “Zero Impact”

Just when we thought we'd have to turn in our running shoes for a lifetime of water aerobics and yoga, along came so-called "zero impact" cardio machines, aka Ellipticals. We were thrilled! No more knee stress, right? Well, the University of Wisconsin-La Crosse did the research to find out.

Not all cardio machines are safe for your knees

The Biomechanics Laboratory of the Physical Therapy Program at University of Wisconsin-La Crosse ran a scientific study comparing the knee stress resulting from two cardio machines and showed how these stacked up against stress under the kneecap from four different non-equipment-assisted activities.

The exercise equipment tested was the Cybex Arc Trainer and the Precor AMT cross trainer.

The researchers discovered that there was a big difference between knee stress experienced on the exercise equipment. The peak knee stress sustained on the Precor AMT was 141% greater than knee stress experienced on the Cybex Arc Trainer. These findings could be compared to other activities, such stair climbing, squatting, lunging – even walking!

Comparing Patellofemoral Joint Force Between Leading Cross-Trainers

As you can see in the chart above, stair climbing posed the most knee stress, followed by using the Precor AMT. On the other hand, the Cybex Arc Trainer caused the least knee stress of all the activities assessed in the study.

Reducing Knee Stress At The Gym

What does this mean for your gym and its members? Not all cardio equipment is the same, especially when it comes to knee safety. Whether you're training a rock-solid athlete, a middle-aged soccer mom, or a skier coming back from injury—the Cybex Arc Trainer provides the most knee-friendly workout, without sacrificing results.


Cybex is a provider and manufacturer of premium commercial fitness equipment. Content featured in the Cybex Fitness Blog is meant to inspire healthy living and wellness and should not be taken as medical advice. As always, be sure to consult a physician if you are unsure of your individual exercise readiness or have a pre-existing medical condition. While these programs offer great benefits, there are many considerations that should be weighed before attempting any type of physical activity.

Comments (3) -

  • Jeff Staples

    10/27/2016 3:24:18 PM |

    220 lbs, 62 years, some knee pain in one knee.

  • Bob Fisher

    12/21/2016 7:50:33 AM |

    How do you reduce knee stress other than by using the Arc Trainer?

  • Duncan Lawrence

    12/22/2016 10:48:38 AM |

    Hi Bob,

    If you're concerned about knee stress, you should definitely work with a personal trainer or medical professional to discuss your options. The Arc Trainer is much less stressful on the knees that other ellipticals/cross trainers, but you still should work with someone who can help tailor a program directly to your needs.

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