Vivian Grisogono

How should knee exercises be done?

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A query about locking the knee as part of knee exercises: why is this to be recommended?

Query 1: I came across your vastus medialis video on YouTube where you left the following comment [in reply to a query]:

"One tip for the future: if you do knee extension or leg press exercises, whether with light or heavier weights, always lock the knee straight at the end of the movement. Failure to do this is a major cause of kneecap problems from weight training. In principle, every knee-bending activity or posture should be mitigated or balanced out by knee extension. (If you want an explanation of why the fashion for not locking the knee crept in, I can give it to you another time!)".

I'd be interested to hear your explanation of where the fashion came from. I was under the impression that because the lower leg rotates just before locking, it was wise to avoid locking under high load squats etc. where friction with the floor prevents the foot rotating with the lower leg.

On a similar note, when standing, would your advice be to stand locked or with a slight bend in the knee?

DR, 42, United Kingdom

Response 1: Thank you for your query about straightening the knee.

The fashion for avoiding straightening the knee in exercises which involved bending the knee arose in about the early 1980s. It appeared to originate in the United States, and at that time there were new, sophisticated exercise machines being designed which deliberately blocked full knee extension at the end of the leg press and knee extension exercises. It took some time for the ill-effects of this to show up. Doing resisted or weight-bearing bent-knee exercises without fully straightening the knee bulks up the main parts of the front-thigh muscles, but contributes to relative weakness of the vastus medialis obliquus muscle. The VMO's primary action is to help full extension of the knee, and to lock the kneecap in place when the knee is fully extended. Relative weakness of the vastus medialis obliquus is a main cause of patellofemoral pain. When that effect became obvious, through people getting injured doing the limited range extension exercises, the advice changed, but unfortunately many fitness instructors and other exercise practitioners were so used to the idea that straightening the knee fully was a Bad Thing, that the contrary advice was not universally heard or accepted. So the mistake persists even now, and in too many places. 

The situation has been complicated by another (erroneous) concept, that one can strengthen the vastus medialis obliquus muscle by doing bent-knee exercises. (This one originated in Australia, around the mid-1980s) This is incorrect, in view of the VMO's primary functions. When the VMO is working well, bent-knee exercises are essential to make sure it works correctly throughout the knee's full movement. But that is only in the latter stages of rehabilitation following any knee injury or problem.

Why did the fashion, or indeed phobia about straightening the knee arise in the first place? It seems it was a misunderstanding of biomechanics. In a normal healthy knee, when the joint is fully straightened, it becomes slightly concave: if you sit on the floor and straighten the knee, the back of the knee presses into the floor and the foot lifts off the floor a little way. This movement is called hyperextension, and is usually limited to about 10 degrees or so. However, some (relatively very few) people have excessively mobile joints, with an excessive range of hyperextension, which can cause problems of pain and/or instability. That is a particular condition in which it is unwise to practise hyperextension exercises for the knee (or whichever joint is affected), because it will of course increase the imbalance. A standard treatment for this problem is to focus on strengthening the opposite muscle group in its middle and inner ranges - ie for the knee, working the hamstrings to bend the knee from a right angle to its fullest degree of flexion. (At the same time, good function in the VMO has to be maintained, using fine control of the VMO movements, but no forceful hyperextension.)

The normal knee is designed to bend fully and straighten fully, and the muscles which perform these movements need to be maintained and kept in good balance. It is as much a mistake to avoid bending the knee fully as straightening it fully. When the knee is fully bent, as in a full squat, it's the only position where the back ends of the soft cartilages (menisci) are lubricated by synovial fluid, which is important for their elasticity. Limiting the squat to the half-squat position misses out on this vital function. (If the menisci are not properly lubricated, they are more prone to degeneration or injury damage.)

In my Youtube comment, I referred to light or heavier weights. With very heavy weightlifting or powerlifting, many factors come into play. It is still the case that the knees should be straightened at the end of the squat movement, and the VMOs should be activated when the knee is straight to draw the kneecaps upwards in order to preserve the primary function. Actually, a good powerlifter automatically braces the knees straight at the end of the lift from the squat. It's a natural part of the dynamics of the movement. The rotation of the knee that you refer to happens automatically. The important element is to get the legs into the right position to start with. The main danger of powerlifting is over-balancing, or trying to lift beyond one's capacities. I guess these are hazards of the game! Lifting very heavy weights is attritional for the body's joints: at the very least, it should not be started until the body is fully mature, although weightlifting techniques with light weights can and should be learned from a younger age.

Standing? I'm not sure what you mean here? If you are talking about standing still in the normal course of things, no I do not recommend either locking the knees straight or holding them slightly bent. By doing either of those, you would block the circulatory flow and create tension which would certainly disrupt the knee's normal flexibility, if you had to stand for any length of time. By holding the knees bent, you would undermine the VMO. In standing, I recommend standing in good alignment (ie on both legs evenly) and doing whatever movements are possible to keep the circulation going. In some cases, one can actively go up and down on the toes; more often in social situations, movements have to be limited to bending and straightening the knees alternately very slightly - I'm told that soldiers on parade use this to prevent fainting!

I hope this is all comprehensible. Now you know why I didn't want to set it all out in the limited space on Youtube. Do feel free to contact me again if you have further queries.

Query 2: Regarding the standing, I stand at my PC at home for an hour or two per day to help compensate for sitting around all day at work.  I have been standing with a slight bend in the knee as this was advised by Esther Gokhale in her otherwise good book "8 steps to a pain free back".  From what you say, I'll avoid this in future and stand with straight (what I call locked) knees and regularly bend the legs or swap my weight from side to side to aid circulation.

To strengthen my VMO, I note the exercises on your website but feel that the weighted exercises are required to bring my VMO up to the same strength as the other quads after years of exercise without full extension.  I was planning to change my squats to full range and do leg extension reps over a limited range of motion from full extension to 20 or so degrees flexion - does that sound reasonable to you?.

I was also thinking about this in relation to cycling - am I correct in thinking that the seat height should be set such that the leg is in full extension when the pedal is at the bottom?

Shame this simple info is not more widely known.

Response 2: Many thanks for the further email. I too feel it's a pity that simple self-help information about posture and exercise based on functional anatomy and many years' experience isn't more widely known. But then again, I know a lot of people who have been privy to the information, but they simply haven't accepted it, and of course it's their right to choose how they live their lives and handle their health & injury issues! I take the view that those who do want to take advantage of this knowledge will find it and use at the right time in their lives. That's already, in itself, very rewarding.

Re: Standing. I think it might be helpful to differentiate between standing up straight and standing with the knees locked straight. To lock the knees, you actively contract the thigh muscles, so they are tense, and during that time the circulatory flow is restricted. Obviously you can't stand like that for any length of time. The human body has evolved to allow standing to be an efficient posture through the action of the postural muscles which hold us up against gravity. The line of gravity passes through the body when we stand straight: at the knees it passes more or less through the centre between the joints, and at the lower end finishes just in front of the line of the ankle joints (which is why the soleus muscle is so important, and why I strongly recommend the soleus exercise of going up and down on the toes with the knees straight, relatively slowly and with full control). So in essence, your body can be relaxed while standing, you shouldn't have to think about it. But to avoid pooling of the blood through the action of gravity, it's helpful to do the little leg movements I suggested. You may be in a position to do more extensive exercises such as squats and arm exercises, if your office is private.

Re: full strength for the VMO. If the VMO is functioning properly, and you do not suffer from front-knee pain, then yes, advanced exercises using the knee's full range of movement are a must. As I pointed out last time, powerlifters doing squats work the VMO to the maximum because they perform a rapid thrust upwards to lift heavy weights. High speed movement is very helpful, and squat jumps are a great knee strengthener. One can start with squat thrusts at first, but make sure that the legs are kicked out fully straight at the end of the movement.

For full VMO and front-thigh function, one should also pay attention to eccentric work, where the muscles pay out against gravity. This means doing some squats, knee extensions or leg press exercises, doing a quick press to straighten the leg(s), then a slow controlled return to emphasize the eccentric (paying-out) mode of the muscle work. 

However, all of the above should only be used when the VMO is functioning optimally, and the knee can straighten and bend fully with no discomfort.

Re: cycling. Yes, in my opinion the saddle should be set to allow the leg to straighten pretty well fully on the down-push. Sometimes it helps to drop the heel at the end of the movement, to emphasize the knee extension.

Incidentally, I always recommend drinking plain water regularly during the day, from early morning onwards, to avoid relative dehydration. It is all too easy to forget this in winter! It's best not to drink a lot in one go, but rather small quantities at regular intervals during the normal day, with more if you do any strenuous exercise.

Query 3: Out of the three knee books that you've written, which would you recommend reading first or does the latest book cover the contents of the prior ones?

Response 3: I've written two books on the Knee, a little one, 'Knee Health' and a more recent one 'The Knee', which is also more comprehensive. Which of these might be useful depends on what you are looking for! For general purposes, my guess is that the second edition of 'Sports Injuries a Self-Help Guide' would probably be the most helpful, as it was only published in 2012, and contains a lot of information to help overall health as well as specifics. If you have any queries about particular injuries or problems, of course you can ask me by email.

Query 4: Some background: I have an office job. I get anterior knee pain when walking down hills or after a few hours dancing to house music.  I speed walk 2 miles four times a week and work through about 20 weight exercises over a two week period.  Due to bad advice, I've been standing with bent knees and avoiding straightening the knee during weight exercises.  I also suffer from back pains but only whilst in bed and only after about 7 hours.  I'm mainly interested in how to overcome my pains, exercise safely and efficiently and be healthy.

Response 4: It sounds as though you can correct your front-knee pain relatively easily, simply by doing the correct versions of the VMO exercises, and by stretching the front-thigh fully (not forcibly).

Stretching the front-thigh, lying on your stomach, is also very useful as a preventive measure if you do it after dancing, walking etc.

If you do not have pain squatting, it can be helpful to do quick squats, making sure to lock the knees at the end of the movement. Again, this helps overall mobility in the knee and kneecaps. For full muscle balance, and only if it does not cause pain, one should do the squats with a controlled, slower downward movement (for eccentric control of the front-thigh muscles) and quick upward movement to straighten the knees.

If in fact your VMO is not functioning adequately, and you can't correct it by exercises alone, the best solution is to use the muscle stimulator, as I've described on Youtube and in my website... if you want me to check on how you're doing any particular exercise, you can always send me a little video by Jumbo mail.