Saturday, October 15, 2011

Why I Think Cycling May Be the Best Activity for Rehabbing Bad Knees

A bold claim! And somewhat ironic, I suppose, as readers of Saving My Knees know I damaged my knees cycling and was unable to ride my bike again for many months, even as I plowed forward with my recovery. So in my case, I got better largely off the bike.

Also, time for the disclaimer dance: I don't think cycling is the best activity for everyone suffering from chronic knee pain. It's dangerous to generalize in the world of knee pain, because different knees often respond best to different things.

For example, one thing needed to ride a bike: good range of motion. If, every time you push your bad knee through the pedal stroke, you experience a painful clicking, or some other type of discomfort that recurs with each revolution, cycling most likely isn't a good activity for you, at least right now. That's partly because good cycling form is about spinning, or making lots of revolutions, every minute (Lance Armstrong, if I recall correctly, used to time trial at 110 rpms -- try doing that on a stationary bike and watch your legs fly!) So you need a decent range of motion that your knees can move through without hurting or "catching" too much, because they will be repeating that motion, again and again and again.

Okay, now that the big caveats are out of the way -- why am I such a big fan of cycling for bad knees?

(1) You want a high-repetition, low-load activity. That's exactly what easy cycling is.

Notice the word "easy." No hills, no sudden accelerations! A moderate rate of spin will get you 80 rpm on a bike -- that means you're flexing your knees 800 times in 10 minutes, or 2,400 times in half an hour. If your cartilage needs thousands of repetitions to spur positive adaptation (i.e. strengthening), this is an ideal exercise, it seems.

(2) Cycling is not a "bone accretive" activity.

If you need stronger, denser leg bones, one activity that won't be prescribed for you is cycling. Riding a bike is a low impact form of exercise that uses a smooth, fluid stroke. It doesn't build up bone mass. (Which leads to the paradox that the cyclist with the heavily muscled thighs who just blew by you on your daily walk may have lousy bone density.)

That can be a good thing, if you've got bone spurs in your knees already from arthritis, which is common with chronic knee pain. Bone spurs can interfere with the normal movement of a knee joint and can be an impediment to the healing of cartilage (as shown in this study: Ding C. et al., “Natural History of Knee Cartilage Defects and Factors Affecting Change”). Cycling should help you strengthen the soft tissue without promoting the formation of unwanted bone.

(3) It may cause your knee cartilage to thicken.

When the knee cartilage of triathletes was studied, an interesting discovery was made. The patellar cartilage was slightly thicker than normal (Muhlbauer R. et al., "Comparison of Knee Joint Cartilage Thickness in Triathletes and Physically Inactive Volunteers Based on Magnetic Resonance Imaging and Three-Dimensional Analysis"). Assuming this was a solid finding that will be reinforced by other studies, what might it tell us?

Well, triathlons generally consist of three activities: swimming, running and cycling. I doubt that swimming, in particular the overhead crawl stroke that you'd expect a triathlete to be doing, promotes the formation of more cartilage under the knee cap. Nor would I expect running to achieve this effect, with its harsh impacts absorbed mainly by cartilage at the end of the leg bones.

Cycling appears most likely to be responsible. Just look at the angle of the knee during the force-exerting part of the pedal stroke. Hopefully future studies will clarify whether cycling does encourage cartilage growth.

(4) Strong quads!

Anyone who reads this blog regularly may be thinking, "But wait a minute -- aren't you the guy who thinks focusing on strong quads is a mistake for people who have chronic knee pain?"

Yup. That's right. But these are two different things.

Having strong quads is great and surely does protect against developing knee pain. Acquiring strong quads through exercise, when your knees tolerate that exercise well, is also great. What doesn't make sense to me: Focusing on strengthening your quads when your knees are damaged and weak and the quad-strengthening exercises only cause more pain.

One nice thing about a cycling program, if you're patient, is that the gentle cycling that you start out doing, to heal your joints and strengthen your knees, can gradually be intensified to the kind of workout (which I do now) that will really develop your quads. Trust me, I know. :)


  1. I am currently trialling shorter cranks. Normally ride 172.5mm cranks, and am now riding 150mm cranks. It reduces the range of motion a little as I was finding the top and first third of my pedal stroke uncomfortable. Have raised my saddle a corresponding 22.5mm to get the bottom of my pedal stroke the same.

    Riding for short periods on indoor trainer. Am not getting out of saddle at all (and hence no road riding) as I find the out of saddle position where I need to manage my body mass dynamically is bad for my knees.

    150mm cranks are expensive to buy so I bought some 175mm cranks SRAM Apex that are not hollow in the crank arms and drilled and tapped them to my shorter requirements. Other possible options would have been a kids bike cranks, a more commercially available 165mm crank, I think some manufacturers are now making 160mm cranks.

    Have really enjoyed reading your book and blog Richard. It is great to find someone who is thinking rather than just following. An injured knee has been a great chance to reflect on how I do things an learn a pile of new stuff. Enjoy.

    1. Thanks for dropping by. That sounds like a good idea on the shorter cranks, if you've got the mechanical aptitude (which you obviously do) to modify them. Never thought about that option, but it makes a lot of sense.

  2. Hi Richard. About 2 years ago I began experiencing pain in my knees going up and down the stairs after workouts. It gradually got worse and worse until I decided to see a doctor. I received x-rays, 2 cortisone shots and the knowledge that I don’t have arthritis. He said “If it doesn’t hurt, don’t do it.” I worked out regularly 3-4 days a week so this was a blow. I pouted around, got depressed, gained 20 pounds and about 1 year and half later finally started seeing a trainer to help me get back in shape. It was very, very slow progress but after about 6 months I was able to go up and down stairs without pain. However, the workouts began to get increasingly frustrating because the strength training exercises pretty much all hurt. Squats were terrible. My trainer was great, really positive and kept trying to motivate me but it seemed like everything he tried hurt. So I quit and started reading up on knees and ran across your blog.
    Last fall, my husband and I first saw pedal assist electrical bikes all over Europe. I tried riding a bike when my knees were at their worst and couldn’t. But I tried a stationary bike again and this time had NO problem whatsoever! So my husband and I walked into the bike store and I walked out with a Trek Lift. Without sounding corny, it has changed my life. I ride my bike every day I can. I feel normal again. I feel like I’ve actually worked out. My husband and I used to ride together but stopped due to my knees. Now I leave him in the dust! He loves it because I push him to ride harder and sometimes even drafts off me. LOL! I’ve found that I use the motor the most on very steep hills, when I need to push off at a stop sign, or cross the road quickly. The bike feels best for me in the “ECO” mode in a middle gear. It has the smoothness of a stationary bike and I'm still working to pedal. Plus all the fun of riding outdoors. The best part is that my knees feel better than ever! (My knee problems stem mostly from pressure on the knees, for example: hopping up and down on my toes. But luckily I’ve never had any problem walking.) I wanted to share my cycling SUCCESS story and maybe it will inspire someone else will give a pedal-assist bike a try. Thank you for sharing your success stories too! Karen

    1. This is a great story! I love it. Love your attitude and spirit too. All the best.

  3. I just came across the above comments about cycling - to which I agree fully. In my case,in addition to cycling, swimming was also beneficial to me - especially taking long walks on the sand (i come from a Mediterranean country) immersed up till the waist and taking it gradually with some board kicking too - for information I was diagnosed with Chondro grade 3 (1st MRI showed complete ACL tear, but second MRI, proved otherwise). When sea was cold it helped even more :)

    I also did an effort in trying not to focus too much on the knee pain etc - shifting my mind on more pleasant stuff helped tremendously. Stress is a huge negative contributor. At the beginning of the injury (8 months ago), walking, going up the stairs and getting up from a seated position was very painful - now I must say that it feels much better. So i now look forward to increase the intensity of the cycling and continue with the swimming (indoor pool).

    I would like to add Richard that I did post a comment earlier on (2 months ago) mentioning that a short weekend break/walks with coffee breaks in between made me realise that to make my knee pain feel better i need to take it slowly and listen to my pain and not rush into things (muscle strengthening etc).. Thanks again for your book as it helped me to take the right direction!

  4. That's great, and thanks for dropping in again. Please come back and update us later. It's really good to hear from people who are doing things that work. Also, very true what you say about stress.