September
12

Knee Extensions Improve Torque…and why I still don’t like them.

James: On page 22 of the Oct 2011 issue of Bicycling magazine talks about using knee extensions to improve your ability to turn a crank. A new study found that three weeks of thrice weekly strength training for the knee extenders improved torque by 17% among older cyclists. Since I’m approaching 70 this month and still an avid mountain biker, (so much fun to ride these spouts into the ground)… I seem to remember that you felt knee extensions were not worth while. Let me know what you think.

Gregg/OMR (Old Man Riding)
Warriors Society
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Gregg,

Thanks for posting this question, I think that it highlights a couple of points that are good to raise. There are three things you need to consider to when looking at that study…

First, everything works for a few weeks, especially for people that have never strength trained. I don’t have the reference for the study to check (post it and I’ll be happy to take a look at it) but I’d be willing to bet money that the subjects were largely inexperienced strength trainees. You can do almost anything with someone who has limited strength training experience and produce some results.

You also have to look at how they were tested and what that really means. They may have increased power output in the lab but what does that really add up to on the bike? You have to know the subjects and the testing procedure to really have any idea of how applicable that 17% increase really is.

Second, there is a difference between performance and durability. Many things that can result in a short term performance increase can also lead to overuse injuries in the long run. What if the increase in torque is also coming with more stress being placed on the knee by teaching the body bad movement habits that rely on knee extension and not hip extension? What’s the trade-off in the long run? If your knees are taking a pounding then are the performance increases worth it? I’d argue that they are not.

Lastly, the fact that some strength training increased pedaling torque isn’t a newsflash, we’ve known that for a while (why the lab guys like to study the same stuff over and over is beyond me). What would have been more interesting is looking at knee extensions vs. a better exercise. I guarantee you that a well executed deadlift or kettlebell swing would have lead to even better results. I like to get the most bang-for-the-buck with my exercises and so I pick the most effective exercises like deadlifts and avoid the junk exercises like knee extensions.

When you all these points into consideration you can see why knee extensions are still on my list of 4 Exercises Every MTB Rider Should Avoid. There are better exercises that will result in more real world performance increases with much less stress on the knee so it is largely a waste of time. Hope this helps…

-James Wilson-

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  1. Don says:

    From a medical standpoint leg extensions put maximum stress on knee cartilage and should be avoided. Got this advice from an Orthopedic Surgeon and a rehab nurse after surgery.

    Reply • September 12 at 8:54 am
  2. Harry Munro says:

    I would like to see the exact same study done with deadifts instead of knee extensions. I reckon the subjects would get more than a 17% increase in crank torque.

    Reply • September 12 at 9:19 am
  3. VM says:

    Gotta go with James and the medical professionals on this one. Considering joint stresses and movement patterns with open vs closed chain exercises the benefits of knee extensions are quite limited.

    Researchers can be quite behind the curve on learning. If you tried to describe the shortcomings of the study to those who wrote it you’d likley get a glazed eye response. Grad students tend to be the worst. They only know what they’ve learned in the lab and real world learning and application are lacking. (Assumptions as I have not read the study either). However, dealing with the very issue that Kinesiology lab professionals/professors being in charge of a national certification here in Canada can really make a mess of things — and I’m a Kinesiology grad. It’s 2011 and they still think a sit and reach test is a valid measure of lower body flexibility and that crunches with a metronome is a good way to test ab strength and spine health…

    Deadlifts, step ups, single leg squat are going to be much better choices. And at 70 yrs old having the required mobility to do them well is going to be paramount not mention the added benefit of bone density maintenance and testosterone levels that aren’t going to be seen with isolation exercises.

    Reply • September 13 at 8:56 am
  4. Carlos says:

    James, I know you are not a doctor or a therapist but, what about knee rehab (broken patella – no surgery just a fiberglass cast)? I’ve been swimming a lot, and the doctor gave me green light to start riding ON THE ROAD only…
    My leg is basically as strong as a 5 year old… so for starters, would it help before moving on to more complex excercises? I have tried doing squats with no weight at all, but I feel (and see) all my body weight being unconsciously moved with my good leg. Its easy to figure out I need to isolate my injured leg, but then again, I don’t thinkI have the strength or confidence to do single leg squats on my recovering leg. So what would be your suggestion on that?

    I was 2 months trhough your program, and I can’t wait to start again.

    Reply • September 24 at 3:02 pm
    • bikejames says:

      Movement is not about individual muscle strength, it is about the ability of the body to coordinate itself and to fire the right muscles in the right sequence. What that means is that you can’t strengthen the quad in isolation and expect for it to automatically contribute more to the squat. I think that you would be better off finding a way to regress the squat, like holding a TRX or something to take some of the weight off so you can do it right. Find a way to regress the movements, not isolate and strengthen muscles.

      Reply • September 26 at 12:50 pm

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