Saturday, June 8, 2013

Why You Need to Know About the “Envelope of Function”

Ah, where to begin?

This will be a two-parter because there’s so much to say.

First, anyone who’s read Saving My Knees knows that I openly acknowledge a huge debt to Doug Kelsey, a very smart physical therapist who heads a clinic in Austin. His writing showed me (1) Bad knees can get better; don’t listen to any doctor who says they can’t (2) The right kind of exercise to rehab a bad knee joint is low load, high repetition.

At some later point, I found Paul Ingraham on the Internet. Ingraham, a former massage therapist in Vancouver, wrote long essays that were sharply reasoned and easy to read, often debunking things that 99 percent of his colleagues believe. He showed me that (1) stretching probably isn’t of much use at all (2) physical therapy’s obsession with “crookedness” has led the profession down a questionable path.

So I had managed to stumble across, quite fortuitously, two therapists whose insights possessed great appeal. All that was missing, really, was a doctor to provide a more formal framework for the right way to understand chronic knee pain.

Enter Scott F. Dye.

I’ve been aware of some of his ideas (such as the “envelope of function” and the importance of tissue homeostasis) for a while, but only recently (because of a reader comment) was prompted to look into them more deeply. And I’m glad I did.

The idea of the “envelope of function” is the cornerstone of his thinking on nagging knee pain. He describes it as “the range of painless loading compatible with tissue homeostasis of a joint without causing structural or physiologic injury.”

In other words, there’s an optimal range of load-bearing activity for your bad knee, within which healing can occur. If you drift outside of this range, or envelope -- either by pushing your knee too hard or not placing any demands on it at all, which leads to its own problems -- you’ll thwart that healing process.

Simple, and spot on, from my own experience.

Dye identifies a problem many of us face after hurting our knees:
The envelope of function, or the safe range of painless loading, frequently diminishes after an episode of injury to the level where many activities of daily living that previously were well tolerated become symptomatic, leading to the prolongation of symptoms.

This is exactly the issue for so many people, but they don’t modify their behavior in response. The above quote brings to mind a wince-inducing comment I recall reading once from someone who couldn’t climb stairs without pain. His solution? “I just pop a couple of Advil.”

Umm, right.

And people like that wonder why their knees never heal?

So if you want to fix your bad knees, it’s important to determine your own “envelope of function” and faithfully stay within it, healing slowly and steadily. Of course that does raise a bunch of interesting questions about the therapeutic implications of an “envelope of function” approach to beating knee pain.

Next week I’ll look at some of those.


  1. This sounds interesting. Looking forward to learning more.

    I with ya on the pill thing. I need the pain as a warning system telling me "stop. Something is wrong. If you keep going you'll wreck more damage."

    In fact, I would prefer it if my knee would tell me right away (via pain signals) that I'm damaging it rather than it tell me 24-48 hours after I've damaged it.

    On the other hand, some people recommend to take anti-inflammatory to get any swelling down. So, maybe that is a good idea. I'm on th fence on that one.

  2. I hear you Knee Pain.

    My knees have some level of discomfort all the time (except when sleeping) but often feel better when moving (walking, swimming, gym) and worst when sitting at a desk. So it is very easy to get lulled into an envelope exceeding situation as they feel better moving. I only know I've over-done it afterwards.

    But I'm slowly learning. I had 1-2 days recently at a conference where my pain levels were very low - just swimming, a bit of walking, and not constantly sitting at a computer seemed to be the key.

    Then I got back home, got cabin fever and figured I'd just try an easy flat 30min spin on the bike - doh!


  3. Hello Richard,

    I read your book the night I booked an arthroscopy with a surgeon. It was a relief to read something that was not trying to sell me something, or said the same old, same old.

    So I started trying to find the sweet spot of not too much, not too little. I'm a martial arts teacher and it was eaaaasy to do too much.

    I just spent a weekend with Ido Portal. Brief synopsis of his work - people need to move, not rest! Joints can get stronger subject to the right stresses. A lot of what sports scientists have described as 'bad' for knees is because people have lousy movement, and lousy movement can make anything bad.

    So to cut to the chase, Ido recommends squatting. It is a natural human pattern which we've lost due to chairs (I know how much you've enjoyed chairs!). The squat is a resting posture, and you see people happily squatting and chatting in Asia.

    Now I squat minimum 30 mins through the day. Eating, waiting for the metro, between upper bod exercises, writing on my ipad... It seems to work for me so far. Pain is less, I feel fine going up and downstairs again. Getting full extension back in my knee. There are some things I'm not about to start again... yet, but this is already good.

    Thing is lots of people really can't squat anymore. Here's an Ido video with some exercises to make it easier.

    and another which hints at some of his other joint prep work. Warning Ido does not do gentle/politically correct. What he does gets results, look beyond the provocation :)

    usual caveats apply - listen to your body!!!

  4. Edward, I took a look at the Ido Portal videos. Very interesting stuff! Def like what he says about movement and use it or lose it. Sometimed its easy to get caught up in my knee rehab and forget that the rest of my body needs movement, too. Not just my knee. That is fascinating you spent a weekend with him.

    Today I did pedaling on the recumbent bike in the gym
    for my knee therapy, which is frankly pretty boring to me. Suddenly it occurred to me I could work out my upper body at the same time! I grabbed two dumbells from the rack and then did bicep curls and shoulder raises and some tricep exercises, too. And, this actually kept me entertained so that I actually biked longer than my boredom tolerance usually allows. :)

    Patience is difficult. Today I did my "land exercises for mt knee." so, next my plan is to do water exercises. But. I want to heal as fast as possible so I want to do the water exercises tomorrow. Right? But, What I think makes my knee happier is to not do any exercise other than "movement" the day after. Let the knee rest. Then, two days later do the water exercises.

    But it's hard to be patient. Especially as I'm starting to feel better.

    Today I attempted to straighten my leg under its own muscle power. Went better than expected. So, I'm very encouraged. I will try again tomorrow or maybe let it rest a day and try the day after.

    This is something I still don't understand: why the nature of my knee pain (severe sudden stabbing pain
    when moving) is significantly different from most people with the same diagnosis (severe burn or ache when sitting.)

  5. Not read the book yet , think I will though , as I'm interested in my own knees and general health . My knees are the flashpoint as it were of a general taxed metabolism that allows inflammation and arthritis to survive in my system. Maybe my torn cartilages aren't healing because of arthritis/inflammation.
    So I am trying some different dietary habits. More raw foods for one , removing pasteurized milk for a month especially in hot drinks being the other.