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This is a follow up question to this one:

Substitute for squats and squat jumps that put less stress on knees

I have found this leg exercise program which tries to minimize knee strain

http://www.wannabebig.com/training/bodybuilding/get-big-legs-with-bad-knees/

One exercise is for example the half one legged squat half deadlift. But there seems to be a consensus that it is better to do full squats.

I feel that it is true that one has less knee stress if one does the The Single Leg ½ Squat, ½ Deadlift compared to a full squat. But it doesn't seem to work the entire legs just like full squats do, so one has to complement The Single Leg ½ Squat, ½ Deadlift which other exercises to get a balanced workout and avoid imbalances. Is my feeling correct? Why or why not? Is there any scientific evidence for it?

Here is a list of the exercises:

The Single Leg ½ Squat, ½ Deadlift
Anterior Lunges
Romanian Deadlifts
Monster Walks
Single Leg Bench Hip Bridge
Sled Pushes
Forward Sled Drag
Reverse Sled Drag

So I am not interested in opinions but what can one say from an exercise scientific point of view about that exercise program, the exercises it uses and about the composition. In particular with respect to avoid knee problems, avoid muscle imbalances and about its effectiveness to strengthening the legs.

Are there any important points I should have in mind when following this program?

For me all those exercises seem to be hamstring/glute dominant, it seems to neglect the quads. So even if those exercises are knee friendly, how can I put it together to get a balanced leg workout? The Reverse Sled Drag seems to be the only exercise which really targets the quads. However if I don't have access to a sledge, how can I put it together in this case?

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It would be good if you could cite core points of the article. Some people may not want to read the full text, but might still provide good answers. But the bigger problem is that all links are prone to link rot which would make your question worthless to future visitors. –  Baarn Nov 25 '12 at 12:49
    
Actually looking at all the exercises, the question is pretty broad, I am not sure if you get satisfying answers unless you narrow the scope of your question. –  Baarn Nov 25 '12 at 12:56
    
Do you already have knee problems you're working around, or do you believe that bending the knees fully will cause knee injury? Related: fitness.stackexchange.com/a/7691/1771 –  Dave Liepmann Nov 26 '12 at 13:48
    
Also, trying to get scientific proof is good, but we have to be careful not to ask too much of exercise science. Sometimes the answer is that there isn't any published research. See fitness.stackexchange.com/a/5775/1771 –  Dave Liepmann Nov 26 '12 at 13:53
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@DaveLiepmann No I don't have knee problems. My motivations for this and the other question are that I want to understand how the things work, and that I want to make my current exercise program as joint friendly as possible to avoid such problems in future... –  Sarah Nov 27 '12 at 13:51
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2 Answers 2

The first thing to realize is that if you have good knees, full depth squats are safe as has been stated on multiple occasions including a link to the kinesthetic breakdown of a squat. A squat and squat jump are two very different exercises though. A proper squat is much less impact on the knees than say running or jumping. Although there is some research that says running isn't as damaging as originally thought. Squat jumps, particularly when weighted, can be very damaging to the knees.

The second thing to realize is that the article is talking about training around an injury. Injuries happen, and if you can't squat or deadlift it's not the end of the world. You just need to find some way to:

  • Train without pain (we're talking injury pain, not just being sore)
  • Make sure we don't introduce muscle imbalances.

The last thing is to realize is that researchers only research what is interesting to them, and what they can get grant money to research. I wish there was a great resource to list all the forces applied to the body during different exercises, but even if there were, the next big question is how to apply that information. While squats have been analyzed (see the kinesiology link) the alternatives you have listed haven't. Further, programming has not been studied, so you are at the mercy of your coach or your own research. When in the absence of good information, you have to perform your own experimentation on yourself. Experimentation requires:

  • A control group (what you compare your results against)
  • A plan for experimentation
  • Executing the plan and gathering observations
  • Evaluating the observations

In this case, I would recommend choosing 2-3 programs to try, and giving each of them at least a 2 month run. One of the programs should be a traditional compound lift program featuring squats as a component--this would be your control group. Once you've come up with the plan, you will need to come up with the data points you are collecting:

  • Pain level, scale 1-5 with 5 being I have to stop now and 1 being no pain
  • Muscle groups exercised
  • Time spent in the gym
  • General observations

There are some things that need to remain as constant as possible:

  • Your diet/weight. Your goal is maintenance, not gaining or losing.
  • The amount and type of conditioning work you are doing (including running, etc.)

Lastly, just do it. You can sit and analyze things for days and months and never move forward. The key is finding something you can do that doesn't cause a bad kind of pain. If you do have injuries see a physical therapist to find out how to correct things. In the mean time you can work around the injuries until they are fixed.

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The Knee

The knee joint bends. To avoid bending it in the interest of injury prevention is folly, since we know from experiment and experience that the dangerous exercise regimen is in fact the one that does not use the knee to its full capability. Like anything else in our body and mind, it's Use It Or Lose It.

The half-squat-half-deadlift, whether single leg or not, is designed to avoid the full use of the knee for people who have pre-existing conditions that prohibit full use of the knee. Everyone who is healthy enough to squat fully should do so. And like any fundamental movement, if you're not healthy enough to squat, you should avoid loaded squats while you work towards fixing those problems.

If you do choose to forgo deep, full squats in favor of the half-squat-half-deadlift, it will be tough to fully replace the squat. The benefit of the exercise is inherent in the loaded full range of motion of the knee, so any good solution will run into the problem of avoiding full knee bends. You can certainly go down that path, but the deep knee bend is what squats are and why they're useful.

The History of "Dangerous" Squats

Brad Schoenfeld's paper, The Biomechanics of Squat Depth (PDF) is an excellent review of the history of this topic:

Squatting safety continues to be a concern amongst some practitioners, particularly as it relates to performance at high knee flexion angles. The theory that deep squats heighten injury risk can be traced to studies conducted by Karl Klein at the University of Texas. Using a self-developed measuring device, Klein noted that weightlifters who frequently performed deep squats displayed an increased incidence of laxity in the collateral and anterior cruciate ligaments compared to a control group that did not (8). Klein concluded that squatting below parallel had a detrimental effect on ligamentous stability and should therefore be discouraged. Soon thereafter, the AMA came out with a position statement cautioning against the performance of deep knee exercises because of their potential for severe injury to the internal and supporting structures of the knee joint.

Subsequent research, however, has refuted Klein’s findings, showing no correlation between deep squatting and injury risk (13,15,18). In fact, there is some evidence that those who perform deep squats have increased stability of the knee joint.

Those references in the sentence I bolded are for the following:

  • Meyers E. Effect of selected exercise variables on ligament stability and flexibility of the knee. Research Quarterly. 42(4):411 – 422. 1971.
  • Panariello R, Backus S, Parker J. The effect of the squat exercise on anterior-posterior knee translation in professional football players. American Journal of Sports Medicine. 22(6):768 – 773. 1994.
  • Steiner M, Grana W, Chilag K, and Schelberg-Karnes E. The effect of exercise on anterior-posterior knee laxity. American Journal of Sports Medicine. 14(1):24 – 29. 1986

To go back in time to review Klein's anti-squat message, try reading this Sports Illustrated article, The Knee Is Not For Bending. A more plainly, on-the-face-of-it-wrong hypothesis I cannot imagine. Among its strange pronouncements:

  • The squat is "of little conditioning value". No one who has ever squatted heavy and deep could ever say this.
  • The blame for knee injuries in football is place on squats weakening players' knees, as opposed to, say, the dangerous nature of the game itself. The lack of correlation between teams that squat and teams that have high injury rates is ignored.

How Squats Are Safe

We do find that the knee does undergo stress at the bottom of the deep squat. This stress is in the form of a protective compression, which keeps the joint stable by reducing movement of individual components. To continue from Schoenfeld:

The reduction in ACL and PCL forces associated with deep squatting is believed to be a result of an impingement between the posterior aspect of the upper tibia with the posterior femoral condyles as well as compression of various soft tissue structures including menisci, posterior capsule, muscle, fat, and skin (9). This helps to constrain the knee joint, significantly reducing anterior and posterior tibial translation and tibial rotation compared to lesser flexion angles. Hence, tolerance to load is enhanced in the deepest portion of the squat with a protective effect conferred to ligamentous structures.

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While your answer ignores the proposed squat alternative, I'm glad this answer is here. –  Berin Loritsch Nov 27 '12 at 15:55
    
@BerinLoritsch Good point. I should make it more explicit that a half-squat-half-deadlift is avoiding full and proper use of the knee. –  Dave Liepmann Nov 27 '12 at 16:02
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