Best and Worst Exercises for Bad Knees

[Gabe Rinaldi]

http://www.prevention.com/article/0,5778,s1-1-111-732-1764-1,00.html

Any comments on this article?

[John Nguyen]

There's a logic disconnection between the title and the body of the article. The title says "Best and Worse Exercises for Bad Knees," yet the article implies that those four exercises are bad for all knees. In any case, if the author were referring strictly to bad knees, I'd be inclined to agree. But then bad knees can originate from different problems and have different symptoms, which generally require exercise modification rather than exercise choice. This may mean limiting range of motion. In healthy knees, however, full range of motion squats done properly and with safe progression is indicated to prepare them for... well, life. To state that these exercises should always be avoided, whether with healthy knees or bad knees, is a generalization that should have died in the dark ages.

-

[Gabe Rinaldi]

A quick search yields the following bio for the author of this article.

http://www.prevention.com/expert/0,5...0-29-0,00.html

It seems that the media and websites like this prevention company cater to people who want info that seems black and white. Tell me what to eat or not eat. Tell me what exercises to do or not to do. I'm not sure if the author knows better or not, but the result is an inaccurate article. Then, the danger is one of our clients (or associates) reads it and thinks we are uninformed.

I suppose this is one use of professional forums such as this - to dispell myths and attempt to spread real info.

[Thom Downing]

Here is the bio....


Prevention Experts

Michele Stanten, Fitness Director
Marathon Central Walking Coach



Prevention Fitness Director Michele Stanten, 36, walked the equivalent of 2.25 marathons in three days to raise money for breast cancer research--but that was before her son Jacob was born. Fitting her training in around a full-time job, taking care of her 4-year-old, spending time with her husband Andrew, and all those other responsibilities we all have, will be more challenging this time. But Michele is determined to come up with some creative solutions that she'll share with everyone to help make training a little easier.

Certified by the American Council on Exercise and a member of IDEA: Health and Fitness Association, Michele is the author of Firm Up in Three Weeks and creator of five exercise videos. She has appeared on the Good Morning America, CBS Early Show, NBC Weekend Today Show, CNN, NPR, and The Jane Pauley Show. Michele has been covering the fitness and weight loss beat for more than 10 years.

[Michael Greeves]

I am always looking for good articles to publish on HyperStrike.com. Maybe we should turn a few of these posts into articles for the masses.

[John Nguyen]

Here is the bio....


Prevention Experts

Michele Stanten, Fitness Director
Marathon Central Walking Coach


Certified by the American Council on Exercise and a member of IDEA: Health and Fitness Association, Michele is the author of Firm Up in Three Weeks and creator of five exercise videos. She has appeared on the Good Morning America, CBS Early Show, NBC Weekend Today Show, CNN, NPR, and The Jane Pauley Show. Michele has been covering the fitness and weight loss beat for more than 10 years.

I don't see any qualification solid enough for her to make such recommendations in her article. Nor does she include references for thos recommendations.

-

JN

[Thom Downing]

I don't see any qualification solid enough for her to make such recommendations in her article. Nor does she include references for thos recommendations.

-

JN


My point exactly. Some physicians condemn squats citing how destructive they are to the knees despite scientific studies and millions of personal experiences to the contrary. One sports medicine doctor explained to me why squats were considered to be bad for the knee. He was actually telling me this between his sets of squats! Since sports medicine doctors only see people with injuries, one can guess why they may have developed this belief. The individuals they treat certainly do not a constitute a random sample, let alone a representative population, as any scientist knows is essential to even attempt to formulate inferences.

The NSCA position statement notes:

"Some reports of high injury rate may be based on biased samples. Others have attributed injuries to weight training, including the squat, which could have been caused by other factors. Injuries attributed to the squat may result not from the exercise itself, but from improper technique, pre-existing structural abnormalities, other physical activities, fatigue or excessive training."

An early study suggested deep knee bends with weights (squats) were hazardous to the ligamentuous structures of the knee. Later studies conclude squats improve knee stability if the lifting technique does not place rotary stresses on the knee (Fleck and Falkel, 1986). The NSCA states:

"Squats, when performed correctly and with appropriate supervision, are not only safe, but may be a significant deterrent to knee injuries."

Torque Force

Contrary to propaganda to the contrary, prominent weight training authorities demonstrate the squat with the knees flexing forward at the same distance as the hips flex backwards. Fredrick Hatfield, Ph.D., the first man to squat over 800 lbs, recommends the knees to extend over the feet with the back more upright for quadriceps development. "Strength Training for Young Athletes" by Steven J. Fleck, PhD and William J. Kraemer, PhD, illustrate parallel squats with the knees extending beyond the feet (knees moving forward with same magnitude as hip moving backwards).

Torque force is necessary for the muscles and joint structures to adapt to the respected overload. If the knee does not travel forward during the barbell squat, the quadriceps muscles are not significantly exercised. On the other hand, injury may result if the knee or lower back experience greater torque forces than what they are accustom.

Fry et. al. (2003) examined the hip and knee torque forces of variations of parallel barbels squats and concluded appropriate joint loading during this exercise may require the knees to move slightly past the toes.

"Try this simplified qualitative method in determining relative torque forces in the knee and hip joints. First take a photograph of the barbell squat in a full decent with a perspective perpendicular to the joints plane. Draw a line of force through the resistance on its center of gravity, straight up and down, parallel to the force of gravity. Gravity acting on both the body mass and added mass (barbell) contribute to the resistance. On the barbell squat, the center of gravity is between the forefoot and heel. If it is not, the individual will fall over, toward the center of gravity. Incidentally, compression forces act upon the joints during the squat stance."

During the execution of a barbell squat, the knees and the hips travel in opposite directions away from the foot, or away from the center of gravity. Draw a second line on the knee joint parallel to the line of force. Draw a third line on the hip joint parallel to the previous lines. A relative comparison can be made on the torque forces of the knee and hip. Typically the torque forces are similar for the knee and hip joints on the barbell squat; the knees travel forward the same magnitude as the hips travel backwards. Generally speaking, during a powerlift type squat (bar lower behind the shoulders and a wider stance) the knee does not travel forward as far as a bodybuilding type squat. The hips typically travel back further with the torso bent forward on a powerlift type squat. This emphasizes the stronger hip extensors and consequently reduces knee extensor involvement. Knee torque is further reduced by a wide stance.

Rotary Force

The practice of adopting foot rotation to selectively strengthen individual muscles of the quadriceps is not supported by the literature (Boyden 2000; Signorile 1995). Knee rotation during the squat can increase the risk of injury (Fleck and Falkel, 1986). Signorile, et. al. states:

"Extreme outward toe point greatly reduces stability, it does not allow the proper drift of the hips as the lifter descends... Extreme inward toe points are equally dangerous, coupling the same problems of stability, base size and lower body drift with the added danger of bringing the knees together...this movement would place high stress on all connective tissue."

Full (Deep) Squat

Kreighbaum (1996) illustrate the safe position of a deep squat with the knees extending beyond the toes. Kreighbaum explains how a deep squat can be performed little chance of injury to the knee. The variables of concern:

speed of descent
size of calves and thighs
strength of the controlling muscles

The primary danger to the knee occurs when the tissues of the calf and thigh press together altering the center of rotation back to the contact area creating a dislocation effect.

The danger of knee injury in this situation may be prevented if either of the following factor are present:

center of gravity of the body system is keep forward of the altered center of rotation

muscles of the thigh are strong enough to prevent the body from resting or bouncing on the calves.

Kreighbaum conclude the deep squat is of little danger to the knees unless these variables and factors are disregarded. Certainly only a limit type of athletes may have a sports specific need to perform a full squat. Olympic weightlifters commonly bounce out of a full front squat with near maximum resistances during both the Clean & Jerk and Snatch. Incidentally, the wide stance during an Olympic style squat further reduces knee torque forces.

During the lower portions of the deep squat the lower back may flex if hip flexibility is inadequate. The risk of injury is increased if the muscles of the lower back are not strong enough to support the flexed spine or the joint structures have not progressively adapted to such a stress. Flexibility exercises can be performed if hip flexibility is insufficient for deep, or full squats. See Full Squat Flexibility.

Customization

If the body has not adapted to a greater torque force, injury can result. It is not necessary to avoid the torque force if the muscles and joint structures can adapt. See adaptation criteria. Of the hip and knee joint, the knee is more vulnerable to injury than the hip due to structural and functional differences. Certainly, if an individual has had a history of knee pain associated with these types of movements, the squat can be modified to to place more torque on the hip and consequently less on the knee joint. Based on the above analysis, this can be accomplished two ways. Simply by not squatting down all the way (e.g. 90°) both the knees and hip do not experience as great of torque forces. Although, this decrease is often off set by the tendency to add more weight to the exercise. Alternatively, by bending at the hip more than the knee, the knee will travel forward less, as in the powerlifting type squat. Recall, the quadriceps will not be exercises as intensely since there is less torque on the knee joint. In addition, since balance must be maintained over the feet, bending over not only transfers more torque to the hips, the torque forces through the spine (lower back) increase; another vulnerable joint for some. Certainly a compromise must be made to evenly distribute the torque force between the knee and the hip / lower back, particularly when both the knees and lower back are healthy.

If the ankle is not flexible enough to allow the knee to travel forward sufficiently, the back will need to be bent forward more to maintain the center of gravity within the foot base. Consequently the lower back with be subjected to greater torque forces. Squatting with the feet wide apart can alleviate part of the problem, allowing the back to be positioned more upright. This solution does not, however, distribute equal stresses on the quadriceps and glutes as would be possible with adequate ankle flexibility.

Until flexibility can be restored, a temporary solution is to elevate the ankles on a board or platform. This will allow the knees to travel forward the same distance as the hip travels backwards. Elevating the heels may present a risk to individuals with adequate ankle flexibility who have not adapted to greater torque forces through the knee. In which case, the knees can potentially travel forward more than what they are accustom. Even when elevating the heels with insufficient ankles flexibility, resistance should begin light and progress only 5-10% every workout until a true workout weight is achieved so joint adaption can occur.

Obviously, individuals who are at a higher risk for specific types of knee pain may choose to avoid certain exercises specifically designed to emphasis the quadriceps involvement by increased knee torque (e.g. front squats, sissy squats, safety squats, barbell hack squats, leg extensions). Likewise, individuals who are at a greater risk for particular types of lower back pain may choose to avoid certain exercises specifically designed to lower back involvement by increased lower back torque (e.g. squats, deadlifts) or hip torque (e.g. deep glute exercises).

[Thom Downing]

Referances.


Boyden G, Kingman J, Dyson R, (2000). A comparison of quadriceps electromyographic activity with the position of the foot during the parallel squat. J Strength Cond Res. 14(4): 379-382.
Fleck, S.J. and Falkel, J.E. Value of Resistance Training for the Reduction of Sports Injuries. Sports Medicine, 3, 61-68, 1986.
Fry AC, Smith JC, Schilling BK. Effect of knee position on hip and knee torques during the barbell squat. J Strength Cond Res. 2003 Nov;17(4):629-33.
Hatfield, F.C. (1989). Power: A Scientific Approach, Contemporary Books, pg. 158.
Kraemer, W.J., Fleck, S.J. (1993). Strength Training for Young Athletes, Human Kinetics.
Kreighbaum, E., Katharine, B.M. (1996). Biomechanics; A Qualitative Approach for Studying Human Movement, Allyn & Bacon, 4, Pgs 203-204.
National Strength and Conditioning Association. The Squat Exercise in Athletic Conditioning, NSCA Position Statements.
Signorile JF, Kwiatkowksi K, Caruso JF, Robertson B, (1995). Effect of foot position on the electromyographical activity of the superficial quadriceps muscles during the parallel squat and knee extension. J Strength Cond Res. 9:182-187.

[Thom Downing]

This is a great post from Exrx.com on Adaptation.

Adaptation Criteria

The body can adapt to practically any natural stress as long as following conditions exist

Warm up
Muscle and joint structures
Specific movement(s) used for exercise

Complete recovery between training bouts
Physical Overtraining
"Lighter" days or periods can be scheduled into program

Increases of intensity or volume are progressive
No more than 5-10% increases of intensity between adaptations
No more than 5-10% increase of weekly training volume

Orthopedic structures are free of Mechanical Deficiencies
Previous injury or disease
Past injury is the greatest predictor of future injury
Orthopedic imbalance
Antagonist strength ratios
Flexibility
Adaptation is still possible

Theoretically, no movement is contraindicative if all the above criteria are met

Injury can occur if orthopedic structures have not adapted to movement, or stress

Limiting range of motion may ultimately increase the risk of injury (See ROM)

Exercises form needs to be relatively consistent so the risk of injury is reduced and adaption can occur.

Current contraindicative movements from some authorities propagate "over generalizations"

[Thom Downing]

J Strength Cond Res. 2003 Nov;17(4):629-33. Related Articles, Links

Effect of knee position on hip and knee torques during the barbell squat.

Fry AC, Smith JC, Schilling BK.

Human Performance Laboratories, The University of Memphis, Memphis, Tennessee 38152, USA. afry@memphis.edu

Some recommendations suggest keeping the shank as vertical as possible during the barbell squat, thus keeping the knees from moving past the toes. This study examined joint kinetics occurring when forward displacement of the knees is restricted vs. when such movement is not restricted. Seven weight-trained men (mean +/- SD; age = 27.9 +/- 5.2 years) were videotaped while performing 2 variations of parallel barbell squats (barbell load = body weight). Either the knees were permitted to move anteriorly past the toes (unrestricted) or a wooden barrier prevented the knees from moving anteriorly past the toes (restricted). Differences resulted between static knee and hip torques for both types of squat as well as when both squat variations were compared with each other (p < 0.05). For the unrestricted squat, knee torque (N.m; mean +/- SD) = 150.1 +/- 50.8 and hip torque = 28.2 +/- 65.0. For the restricted squat, knee torque = 117.3 +/- 34.2 and hip torque = 302.7 +/- 71.2. Restricted squats also produced more anterior lean of the trunk and shank and a greater internal angle at the knees and ankles. The squat technique used can affect the distribution of forces between the knees and hips and on the kinematic properties of the exercise. PRACTICAL APPLICATIONS: Although restricting forward movement of the knees may minimize stress on the knees, it is likely that forces are inappropriately transferred to the hips and low-back region. Thus, appropriate joint loading during this exercise may require the knees to move slightly past the toes.

[Gabe Rinaldi]

Here's a good writeup from the following website:

http://www.stumptuous.com/cms/displayarticle.php?aid=52

Here's the text:

myth #1: squatting must not be done with a full range of motion or you will hurt your knees.

This is probably the worst myth of all. It's one of those "well known facts" which is mysteriously unsupported in the research (it's a well known fact that as soon as you say "it's a well known fact", you won't be able to back it up). According to this myth, full squats (a squat in which the knee joint is taken through a full range of motion, so that at the bottom the hamstrings make contact with the calves) are inherently dangerous, particularly to the knee joint.

While biomechanical research does support the fact that forces on the connective tissues of the knee increase with the knee angle, particularly on the posterior cruciate ligament, there is no evidence that these increased forces actually lead to injury. There is no direct evidence that full squatting causes or even exacerbates knee pain nor damage. I do not know of a single documented case where full squatting led directly to knee injury. Not one! Which is pretty amazing, considering that the clinical literature is positively littered with injury narratives. You'd think we'd see some evidence, but there is nothing, nada, zero. Studies of Olympic weightlifters and powerlifters, both of whom squat with heavy loads, show no increased risk of knee damage in either population. Olympic lifters, in particular, regularly drop to full depth under hundreds of pounds, perhaps as often a hundred times a week or more, for years, and yet their knees are healthier than those of people such as skiiers, jumpers, or runners. No study, short or long term, has ever shown an increase in knee laxity from deep squatting.

In fact, there is strong evidence that squatting actually improves knee stability! The increased strength, balance, and proprioception from regular squatting can make a substantial contribution to keeping knees healthy. Progressive overload (beginning with a light load, then increasing gradually as the trainee is able) assists in strengthening connective tissues and muscles surrounding the joint.

Most interesting to me is the problem with what is usually recommended as "safe": squatting to parallel. At parallel (where the thigh is parallel to the floor, higher than the depth of a full squat by about 30 degrees), the compressive forces on the patella (kneecap) are actually at their highest (Huberti & Hayes, Journal of Bone Joint Surgery, 1984: 715-724). Decelerating, stopping, and reversing direction at this angle can inspire significant knee pain in even healthy people, whereas full squats present no problem. Another exercise which is supposedly "safer" is the leg extension, even though patellar tension and shear forces on the knee joint are demonstrably higher with such an exercise (see sidebar).

It is worthwhile at this point to comment on the things that do cause knee injury. The primary causes of knee injury involve:

a) twisting under a load

b) too much load (for example, I heard of a guy who boasted that he could squat 800 lbs. He had never done it before, and couldn't even full squat half that much, but he decided that 800 was a good round number, and he was going to attempt to quarter squat it. Long story short, knee ligaments did not agree with his assessment)

c) landing unevenly from a jump, especially with straightened rather than bent legs (this is a big problem for folks like basketball and volleyball players)

d) being in a situation where one part of the leg is held stationary while the other is moving (for example, stepping in a gopher hole while running: shin stays in place while the thigh keeps moving)

e) impact to the knee (such as a hit from the side or front in football)

f) squatting in a Smith machine which does not allow proper shifts in weight through the movement, and results in shear on knee and spine

In other words, knee injury usually results from varus or valgus force (twisting of the joint in either direction), inappropriate loading, or forcible shear across the joint. It does not occur simply from taking the knee joint through a full range of motion, using correct technique, and using a weight which is appropriate to the abilities of the trainee.

This is not to say that everyone can immediately leap into full squatting. It is essential to learn to squat in a way that meets your individual needs, and I'll discuss that in Part 3. It is common to have difficulty with a full range of motion in the beginning. If knee pain is felt during the squatting motion, there are a few possible reasons. First, it is important to rule out existing pathology. Some people may indeed have knees that are so damaged that they are unable to squat, but this is rare (and these people are probably walking with a cane). In particular, full squatting is contraindicated for someone with an acute posterior cruciate ligament (PCL) injury, but these types of injuries are uncommon and usually result from something like a car accident. Someone who has rehabilitated a PCL injury can attempt full squats with light loading, and see how it goes. With correct loading and technique, anterior cruciate ligaments (ACL) and medial cruciate ligament (MCL) injuries generally don't present a problem. I know someone who is even missing an ACL on one knee, and has a reconstructed ACL on the other, and she squats quite happily.

Some people may have irritation in the joint due to things like patellofemoral syndrome or age-related degeneration, and the goal initially should be to squat in a pain-free range, while aiming to increase that range and strengthen the muscles around the joint. Some people may experience pain due to poor technique, which includes allowing the knees to cave in or twisting during the ascent. In this case, the trainer should again establish probable cause and direct attention to remedial work (such as stretching and additional strengthening) in conjunction with improving pain-free range of motion and correct technique. In Part 4 of this article, I suggest some stretches and assistance exercises to help you eliminate possible problems.

Do not do an exercise, no matter how great that exercise is, if it causes you pain. Find alternatives or modify the exercise. Full squats are great, and most folks can eventually do them, but nothing works for absolutely everyone.

[Gabe Rinaldi]

Clin Biomech (Bristol, Avon). 2001 Jun;16(5):424-30. Related Articles, Links

Patellofemoral joint kinetics during squatting in collegiate women athletes.

Salem GJ, Powers CM.

Musculoskeletal Biomechanics Research Laboratory, Department of Biokinesiology and Physical Therapy, University of Southern California, 1540 E. Alcazar Street, CHP-155, Los Angeles, CA 90033, USA. gsalem@hsc.usc.edu

OBJECTIVE:To characterize the biomechanics of the patellofemoral joint during squatting in collegiate women athletes. DESIGN: Repeated measures experimental design. BACKGROUND: Although squatting exercises are required components of most intercollegiate resistance-training programs and are commonly performed during rehabilitation, the effects of various squatting depths on patellofemoral joint stress have not been quantified. METHODS: Anthropometric data, three-dimensional knee kinematics, and ground reaction forces were used to calculate the knee extensor moment (inverse dynamics approach) in five intercollegiate female athletes during squatting exercise at three different depths (approximately 70 degrees, 90 degrees and 110 degrees of knee flexion). A biomechanical model of the patellofemoral joint was used to quantify the patellofemoral joint reaction force and patellofemoral joint stress during each trial. RESULTS: Peak knee extensor moment, patellofemoral joint reaction force and patellofemoral joint stress did not vary significantly between the three squatting trials. CONCLUSIONS: Squatting from 70 degrees to 110 degrees of knee flexion had little effect on patellofemoral joint kinetics. The relative constancy of the patellofemoral joint reaction force and joint stress appeared to be related to a consistent knee extensor moment produced across the three squatting depths. RELEVANCE: The results of this study do not support the premise that squatting to 110 degrees places greater stress on the patellofemoral joint than squatting to 70 degrees. These findings may have implications with respect to the safe design of athletic training regimens and rehabilitation programs.

[Thom Downing]

The attached article is a collection of articles, comments regarding full vs. partial squatting.