Article By Arioch at http://www.midwestbarbell.com/articles/squat.htm
Squat Theory and Execution
Written by “Arioch”
The squat should be a standard exercise in any lifters program. Whether the goal is strength, hypertrophy (increase in muscle size), increased accelerative ability, or a heightened vertical jump, the squat is the tool for the task. In addition to working the muscles of the legs, hips, lower back, abdomen, and obliques, the demands of squatting should stimulate a growth response from the body that will carry over into strength and size increases in other areas.
The basic technique of the squat consists in placing a loaded barbell across the shoulders, then bending at the hips and knees, descending into the bottom position, “the hole,” and returning to an erect position. We will examine the squat from the deck up.
Stance. This varies from individual to individual, but one thing is necessary for all who wish progress: you must keep your feet flat on the deck at all times. The center of gravity may be maintained over the center of the foot, but it is generally best to push through the heels. This will help in maintaining bar position and help eliminate a small degree of forward lean. To achieve this, some people find it necessary to curls the toes upward while squatting, forcing their heels flat. The feet should be placed at least shoulder width apart, and some individuals may best utilize a stance nearly twice shoulder width. The narrower stance tends to place more direct emphasis on the quads, and creates a longer path for the bar to travel. The wider stance (often called “sumo”) tends to be favored by many powerlifters, although some have enjoyed great success with a relatively narrow stance. The sumo stance place more emphasis on the adductors and hamstrings. As a rule of thumb, lifters with longer legs will need a wider stance than shorter individuals. However, there are exceptions. A wider stance will tend to recruit both the adductors and buttocks to a greater degree than a narrow stance. (1)
The shins should be a close to vertical as possible throughout the entire movement. This lessens the opening of the knee joint, and reduces the shearing force as well. By reducing the workload that the knee joint is required to handle, more of the work is accomplished by the larger muscles around the hip joint. For powerlifters, this decreases the distance one must travel with the bar, as the further the knee moves forward, the lower the hips must descend to break parallel.
There are several schools of thought on squat depth. Many misinformed individuals caution against squatting below parallel, stating that this is hazardous to the knees. Nothing could be further from the truth. (2) Stopping at or above parallel places direct stress on the knees, whereas a deep squat will transfer the load to the hips,(3) which are capable of handling a greater amount of force than the knees should ever be exposed to. Studies have shown that the squat produces lower peak tibeo-femoral(stress at the knee joint) compressive force than both the leg press and the leg extension.(4) For functional strength, one should descend as deeply as possible, and under control. (yes, certain individuals can squat in a ballistic manner, but they are the exception rather than the rule). The further a lifter descends, the more the hamstrings are recruited, and proper squatting displays nearly twice the hamstring involvement of the leg press or leg extension. (5,6) and as one of the functions of the hamstring is to protect the patella tendon (the primary tendon involved in knee extension) during knee extension through a concurrent firing process, the greatest degree of hamstring recruitment should provide the greatest degree of protection to the knee joint. (7) When one is a powerlifter, the top surface of the legs at the hip joint must descend to a point below the top surface of the legs at the knee joint.
Knee injuries are one of the most commonly stated problems that come from squatting, however, this is usually stated by those who do not know how to squat. A properly performed squat will appropriately load the knee joint, which improves congruity by increasing the compressive forces at the knee joint. (8,(9) which improves stability, protecting the knee against shear forces. As part of a long-term exercise program, the squat, like other exercises, will lead to increased collagen turnover and hypertrophy of ligaments. (10,11) At least one study has shown that international caliber weightlifters and powerlifters experience less clinical or symptomatic arthritis. (12) Other critics of the squat have stated that it decreases the stability of the knees, yet nothing could be further from the truth. Studies have shown that the squat will increase knee stability by reducing joint laxity, as well as decrease anterior-posterior laxity and translation. (13,14) The squat is, in fact, being used as a rehabilitation exercise for many types of knee injuries, including ACL repair. (15)
One of the most, if not the most critical factor in squatting is spinal position. It is incredibly important not to round the back. This can lead to problems with the lower back, and upper back as well. The back should be arched, and the scapulae retracted, to avoid injury. This position must be maintained throughout the entire lift, as rounding on the way up is even more common than rounding on the way down, and people who make this mistake are the ones who perpetuate the “squats are bad for your back” myth. Furthermore, spinal position is essential to maintaining a proper combined center of gravity (CCOG). The farther one leans forward or, even worse, rounds the back, the more strain the erectors are forced to bear, and the less the abdominals can contribute to the lift. To say nothing of the fact that the greater the lean, the greater the shearing force placed on the vertebrae. Proper spinal alignment will assist in ensuring that the majority of the force the spine must bear is compressive in nature, as it should be. Another reason for descending below parallel is that the sacrum undergoes a process known as nutation (it tilts forward, relative to the two ilia on either side of it). At only 90 degrees of knee flexion, the sacrum is still tilted backward, which inhibits proper firing of the erectors and gluteus maximus and minimus. Going through a full range of motion completes the rotation of the sacrum and allows maximal muscular recruitment.
“Squats are bad for your back” is yet another cry of the weak of both leg and spirit. While an improperly performed squat can cause problems, so can improperly performed barbell curl, yet many of the people who use the squat rack only to curl do not seem to have a problem strengthening their elbow flexors. While the squat can be hazardous to the back among the untrained who often incline the torso to an unsafe degree, as well as round the back, skilled athletes have been shown to minimize trunk segment torques by maintaining a more erect posture. (16) It has been positively shown that maintaining an upright torso during the squatting motion reduces both spinal compression and shear forces. (17) Several studies have shown that weightlifters experience not only less back injury and pain that many other athletes, but often even less than inactive individuals, which clearly displays that a proper weight training program, which includes squatting, is beneficial in avoiding injury. (18,19)
The placement of the bar is another very important consideration when squatting. If one places the bar high on the traps, more emphasis will be placed on the quads, and a low bar squat recruits more of the lower back and hamstrings, by virtue of back extension, simply because the lower the bar is placed, the greater the degree of forward lean. Even when high bar squatting, the bar should NEVER be placed on the neck. This is far more stress than the cervical vertebrae should be forced to bear. When a powerlifter squats with a low bar position, the bar should be placed no lower than three centimeters below the top of the anterior deltoids. For other lifters, comfort and flexibility will go a long way towards determining bar positioning. When gripping the bar, at first it is best to place your hands as close together as possible, to maintain tension in the upper back, and to avoid any chance of the bar slipping. As a general rule, the lower you place the bar, the wider your hands will have to be. Anything placed between the bar and the lifter, such as a pad or towel, decreases the force of friction and increases the chance of the bar slipping. It is to avoid injuries that this practice is banned in competition. Also, this will artificially raise the lifter’s CCOG, which makes it harder to balance under a heavy load.
Look slightly upward when squatting, to avoid rounding the upper back. The movement should be initiated from the hips, by pushing the glutes back, not down. This will assist in keeping the shins vertical. On the way down, keep the torso as close to vertical as possible, continue to push the hips back, and push the knees out to the sides, avoiding the tendency to allow them to collapse inward. The manner in which the lifter descends will greatly influence the manner in which the ascent is made. When the necessary depth is achieved, begin ascending by pushing the head back, and continue to concentrate on pushing the knees outward.
One of the most common mistakes made while squatting, or performing any exercise for that matter, is improper breathing. At first, the lifter should inhale on the way down, and exhale on the way up. Many advanced lifters will take several large breaths, hold it all in on the way down, and then exhale forcefully at their sticking point on the way up. This technique, known as the “Partial Valsalva,” requires practice like any other.
There are many other types of squats, but all of them are secondary to the squat itself, which is appropriately termed the “King of Exercises.”
The front squat is performed in a similar manner, but the bar is held in the clean position, across the anterior deltoids, not the clavicles. The hands should be slightly wider than shoulder width, and the elbows should be elevated as much as possible. The bar is maintained as high as possible by elevating the elbows. This allows the lifter to maintain a more upright posture, and increases the emphasis on the glutes, while lessening the involvement of the lower back. This exercise may allow a lifter who lacks the flexibility required to perform a full squat achieve a reasonable depth while improving flexibility. The front squat will place far more emphasis on the quadriceps muscles and less recruitment of the hamstrings takes place. 7 (20) When comparing the squat to other exercises, it is important to note that the squat causes less compressive force to the knee joint, and greater hamstring activation, than both the leg press and the leg extension. (21)
Another popular type of squatting exercise is the split squat (“lunge”). In this type of squat, the legs are placed at approximately shoulder width, but one foot is out in front of the athlete and one is placed to the rear, as if a lifter has just completed the jerk portion of the clean and jerk. The athlete descends by bending the front leg until the knee is slightly forward of the toes. The shin of the front leg should be ten degrees past perpendicular to the floor. It is important to maintain an upright posture when doing so. As when squatting, co-activation of the hamstring serves to protect the knee joint during flexion, (22) which is very important as often a greater degree of flexion will occurring when performing the split squat.
Certain misinformed and so-called “personal trainers” will have people squat in a smith machine, which is, quite simply, an idea both hideous and destructive. This is often done under the misguided “squat this way until you are strong enough to perform a regular squat” premise. Even if one overlooks the obvious fact that it is better to learn to do something right than build bad habits from the start, there are numerous other factors to be considered. The smith machine stabilizes the bar for the lifter, which does not teach the skill of balancing the bar, balance being important to any athlete, as well as the fact that free weight squatting strengthens the synergists which goes a long way to preventing injuries. A chain is only as strong as its weakest link, and the smith machine leaves far too many weak links. To say nothing of the fact that free weights provide a greater transfer of functional strength than machines. (23)Furthermore, the bar moves straight up and down, and very few people squat in this manner, which means that the smith machine does not fit a lifters optimal strength curve. (24) The smith machine also requires that the lifter either squats with his torso much closer to vertical than would be done with a real squat, which mechanically decreases the involvement of both the spinal erectors and the hamstrings. While this would be fine if it was done by the lifters muscular control, when the smith machine does this it is disadvantageous to the lifter by virtue of decreasing the ability of the hamstrings to protect the knee joint. Another mistake made, aside from simply using it in the first place, is allow the knees to drift forward over the toes, the chance of which is increased by the smith machine. As was previously mentioned, this greatly increases the shearing force on the knees. This from a device touted by the ignorant as “safe.”
There is a great debate about the use of belts when squatting, some sources insist that you must wear one, while others state quite the opposite. It is worth noting that there are plusses and minuses to wearing one. Using a proper belt while squatting can serve to increase intra-abdominal pressure (IAP) which will serve to stabilize the spinal column, reducing compressive forces acting upon the spine and reducing back muscle forces. (25) However, muscle activity of the trunk appears to be significantly reduced when using a weight belt, which can lead to the muscles of the trunk receiving a less than optimal stimulus when using a belt. (26) Other proponents of belt use have shown that the use of a properly designed power belt may improve a lifter's explosive power by increasing the speed of the movement without compromising the joint range of motion or overall lifting technique. (27)
Darkhorse on 08-31-2005, 01:03 AM
There are numerous methods of utilizing the squat in any athlete’s training program. While a variety of rep and set ranges are optimal for a bodybuilder who wishes to maximize hypertrophy, an athlete’s must carefully plan a training program to meet their goals. Even though squatting will lead to gains in size, strength, and jumping ability, the more specific the program, the greater the results. When an untrained subject begins lifting, numerous programs produce gains in practically all areas, but this changes rapidly, with limited progress being made unless something is altered. (28)
To utilize the squat to gain in size is both simple and complex. Individuals will respond to a variety of rep ranges in different manners based on fiber type, training history, biomechanics, injuries, etc. Bodybuilders, who are concerned exclusively with gains in size, should squat heavy, as fast-twitch muscle fibers have the greatest potential for hypertrophy. However, sarcoplasmic hypertrophy (growth of muscle tissue outside of the sarcoplasmic reticulum) will contribute to overall muscular size, and is obtained by training with lighter weights and higher reps. Rate of training is once again an individual decision, but as a general rule, the greater the volume of training, including time under tension (TUT) per workout, the longer one must wait before recovery is optimized, allowing supercompensation to take place. A word of caution about performing higher repetitions while squatting: As the set progresses, the degree of forward lean increases. While this is desirable to increase the stress on the hamstrings, it takes the emphasis off of the quadriceps, as well as increases the risk of injury. (29)
An athlete wishing to improve his vertical jump should not only squat, but perform a variety of assistance work specific to both improving squatting strength as well as specifically improving jumping skill. As jumping requires a great expenditure of force in a minimal amount of time, exercises such as squatting should be performed to increase muscle power, as muscle cross-sectional area significantly correlates to force output. (30) When wishing to increase one’s power through squatting to assist in the vertical jump, one must train to generate a high degree of force.(31 ,32 ,33 ) This is done by squatting a dynamic manner, where one is attempting to generate a large amount of power while using submaximal weights. This has been shown to provide a great training stimulus for improving the vertical jump. (34) A program consisting of a session once-weekly heavy squatting, ballistic lifting, and plyometric training, with each being performed during a separate workout, should provide maximal stimulus while allowing maximal recovery and supercompensation.(35,36)
When training to improve one’s overall squatting ability, expressed as a one-repetition maximum (1rm), once again a variety of programs may be utilized. The most common is a simple periodized program where, over time, the training weight is increased and the number of repetitions decreases. This sort of program is utilized by both Weightlifters and Powerlifters alike. A sample periodized program is included in Appendix B. Some sources state that you must train to failure, while others state that one should train until form begins to break down, leaving a small reserve of strength but reducing the risk of injury. It should be stated that there is no evidence that indicates training to failure produces a greater training stimulus than traditional volume training.
Far and away the most complicated, and controversial training program is the conjugate training method. Using this method one trains to develop maximal acceleration in the squat during one workout, and in another workout (72 hours later) generate maximum intensity in a similar exercise to the squat. This is based on an incredibly lengthy study by A. S. Prelepin, one of the greatest sports physiologists of the former Soviet Union. (37) This method also uses the practice of compensatory acceleration, where an athlete attempts to generate as much force as possible, by not only generating maximal acceleration, but by continuing to attempt to increase acceleration as the lifter’s leverage improves. The addition of chains or bands can increase the workload as well as force the athlete to work harder to accelerate the bar. Utilizing this system, the squat is trained for low repetitions (2) but a high number of sets (10 – 12), with training intensities being 50 – 70% of the athlete’s 1rm. Rest periods are short (45 – 75 seconds), and the squats are often performed on a box, which breaks up the eccentric-concentric chain, and inhibits the stretch reflex, forcing the athlete to generate the initial acceleration out of the bottom of the lift without the benefit of the elasticity of the muscle structure.
During the second workout, an exercise which taxes the muscles recruited when squatting, but not an actual squat, is performed for very low repetitions (1-3, usually one). The goal on this day is to improve neuromuscular coordination by increased motor unit recruiting, increased rate coding, and motor unit synchronization. This allows the athlete to continue to generate maximal intensity week after week, but by rotating exercises regularly optimal performance is maintained. For one microcycle, a squat-like exercise is performed, such as a box squat, rack squat, or front squat is performed, then the athlete switches to a different type of exercise, such as good mornings, performed standing, seated, from the rack, etc. for another microcycle, then switches exercises again, often to a pulling type exercise such as deadlifts with a variety of stances, from pins, from a platform, or any number of other variations. Once again, chains or bands may be added to increase the workload. A sample training program is included in Appendix B, and a variety of maximal effort exercises can be found in Appendix C.
Assistance work for the squat is of the utmost importance. The primary muscles which contribute to the squat, in no particular order, are the quadriceps, hamstrings, hip flexors/extensors, abdominals, and spinal erectors. When an athlete fails to rise from the bottom of a squat, it is important to note that not all of the muscles are failing simultaneously. Rather, a specific muscle will fail, and the key to progress is identifying the weakness, then strengthening it. A partial list of assistance exercises is provided in Appendix D. While it is impossible to simply state that if x happens when squatting, it is muscle y that is causing the problem, some general guidelines follow. If a lifter fails to rise from the bottom of a squat, it generally indicates either a weakness in the hip flexors and extensors, or a lack of acceleration due to inhibition of the golgi tendon organ (no stretch reflex – train with lighter weight and learn to accelerate if this is the case). If an athlete has a tendency to lean forward and dump the bar overhead, it generally indicates either weak hamstrings or erectors. If an athlete has trouble stabilizing the bar, or maintaining an upright posture, it is often due to a weakness in the abs.
The above factors assume that proper technique is being maintained. If this is not the case, no amount of specific work will overcome this problem. Drop the weight and concentrate on improving skill, which is far more important than training the ego, and less likely to lead to injury.
Safety is the key issue when squatting, or performing any lift. With a few simple precautions, practically anyone may learn to squat, and do so quite effectively. The rewards are well worth the effort. Squat heavy, squat often, and above all, squat safely.
1 Stance width and bar load effects on leg muscle activity during the parallel squat. McCaw ST; Melrose DR Med Sci Sports Exerc, 31(3):428-36 1999 Mar
2 Ariel, B.G., 1974. Biomechanical analysis of the knee joint during deep knee bends with a heavy load. Biomechanics. IV(1):44-52.
3 High- and low-bar squatting techniques during weight-training. Wretenberg P; Feng Y; Arborelius UP, Med Sci Sports Exerc, 28(2):218-24 1996 Feb
4 An analytical model of the knee for estimation of internal forces during exercise. Zheng N; Fleisig GS; Escamilla RF; Barrentine SW, J Biomech, 31(10):963-7 1998 Oct
5 Biomechanics of the knee during closed kinetic chain and open kinetic chain exercises. Escamilla RF; Fleisig GS; Zheng N; Barrentine SW; Wilk KE; Andrews JR Med Sci Sports Exerc, 30(4):556-69 1998 Apr
6 A comparison of tibiofemoral joint forces and electromyographic activity during open and closed kinetic chain exercises. Wilk KE; Escamilla RF; Fleisig GS; Barrentine SW; Andrews JR; Boyd ML Am J Sports Med, 24(4):518-27 1996 Jul-Aug
7 Chandler TJ and Stone MH. (1991) The squat exercise in athletic conditioning: a review of the literature. NSCA Journal. 13(5): 58-60.
8 Hsieh, H. and P.S. Walker. 1976. Stabilizing mechanisms of the loaded and unloaded knee joint. Journal of Bone and Joint Surgery. 58A(1):87-93.
9 Uhl, T.L. and P.V. Loubert. 1990. Axial compression effect on anterior displacement of the in vivo tibeofemoral joint. Master’s thesis, University of Michigan, Ann Arbor, MI.
10 Shankman, G. 1989. Training guidelines for strengthening the injured knee: basic concepts for the strength coach. NSCA Journal. 11(4):32-42.
11 Tipton, C.M., Matthes, R.D., Maynard, J.A. and Carey, R.A. 1975. The influence of physical activity on ligaments and tendons. Medicine and Science in Sports. 7(3):165-175.
12 Herrick, R.T., Stone, M.H. and Herrick, S. 1983. Injuries in strength-power activities. Powerlifting USA. 7(5):7-9.
13 Panariello, R.A., Backus, S.I., and Parker, J.W. 1994. The effect of the squat exercise on anterior-posterior knee translation in professional football players. American Journal of Sports Medicine. 22(6):768-773.
14 Steiner, M.E., Grana, W.A., Chillag, K., and Schelberg-Karnes, E. The effect of exercise on anterior-posterior knee laxity. 1986. American Journal of Sports Medicine. 14(1): 24-29.
15 Palmitier, R.A., Kai-Nan, A., Scott, S.G., and Chao, E.Y.S. 1991. Kinetic chain exercise in knee rehabilitation. Sports Medicine. 11(6):402-413.
16 McLaughlin, T.M., Lardner, T.J., and Dillman, C.J. 1978. Kinetics of the parallel squat. Research Quarterly. 49(2):175-189.
17 Garhammer, J. 1989. Weight lifting and Weight Training. In: Biomechanics of Sport, chapter 5, C.L. Vaughan, ed. Boca Raton FL: CRC Press. Pp. 169-211.
18 Granhed, H. and Morelli, B. 1988. Low back pain among retired wrestlers and heavyweight lifters. American journal of Sports Medicine. 16(5):530-533.
19 Kulund, D.N., Dewey, J.B., Brubaker, C.E., and Roberts, J.R. 1978. Olympic Weightlifting Injuries. Physician and Sports Medicine. 6(11):111-119.
20 A preliminary comparison of front and back squat exercises [see comments] Russell PJ; Phillips SJ Res Q Exerc Sport, 60(3):201-8 1989 Sep
21 J Biomech 1998 Oct;31(10):963-7 An analytical model of the knee for estimation of internal forces during exercise. Zheng N, Fleisig GS, Escamilla RF, Barrentine SW
22 Biomed Sci Instrum 1997;33:360-5 Co-activation of the hamstrings and quadriceps during the lunge exercise. Hefzy MS, al Khazim M, Harrison L
23 Stone, M. H., Johnson, R. L., & Carter, D. R. (1979). A short-term comparison of two different methods of resistance training on leg strength and power. Athletic Training, 14, 158-160.
24 Phys Ther 1995 Feb;75(2):133-44 Neuromuscular coordination of squat lifting, II: Individual differences. Scholz JP, McMillan AG
25 Lander, J.E., Hundley, J.R., and Simonton, R.L. The effectiveness of weight-belts during multiple repetitions of the squat exercise. Med Sci Sports Exercise. 24(5):603-609. 1992.
26 The Effectiveness of Weight-belts During the Squat Exercise. Lander, JE, Simonton, RL, and Giacobbe JKF. Med Sci Sports Exercise. 22(1):117-126. 1990.
27 Attila J. Zink, William C. Whiting, William J. Vincent, and McLaine, A.J. The effects of a weight belt on trunk and leg muscle activity and joint kinematics during the squat exercise. 1999. Journal of Str Con Res.
28 Influence of two different modes of resistance training in female subjects. Hisaeda H; Miyagawa K; Kuno S; Fukunaga T; Muraoka I
29 Lander, JE, Hundley, JR, and Simonton, Rl. The Effectiveness of weight-belts during multiple repetitions of the squat exercise. Med Sci Sports Exerc. 24(5): 603-609. 1992.
30 Force-velocity relationships and fatigability of strength and endurance-trained subjects. Kanehisa H; Ikegawa S; Fukunaga T
Choi, J. Y., Takahashi, H., Itai, Y., & Takamatsu, K. (1997).
31 Comparison of training effects between power-up type and bulk-up type in strength training. Medicine and Science in Sports and Exercise, 29(5), Supplement abstract 54.
32 Hellebrandt, F. A. (1972). The physiology of motor learning. In R. N. Singer (Ed.), Readings in motor learning (pp. 397-409). Philadelphia, PA: Lea & Febiger.
33 Christina, R. W. (1996). Major determinants of the transfer of training: Implications for enhancing sport performance. In K-W. Kim (Ed.), Human performance determinants in sport (pp. 25-52). Seoul, Korea: Korean Society of Sport Psychology.
34 Wilson, G. J., Newton, R. U., Murphy, A. J., & Humphries, B. J. (1994). The optimal training load for the development of dynamic athletic performance. Medicine and Science in Sports and Exercise, 25(11), 1279-1286.
35 Morrissey, M. C., Harman, E. A., & Johnson, M. J. (1995). Resistance training modes: Specificity and effectiveness. Medicine and Science in Sports and Exercise, 27, 648-660.
36 Kraemer, W. J., & Newton, R. U. (1994). Training for improved vertical jump. Sports Science Exchange, 7(6), 1-12.
37 A. S Prelepin. 1969. Preparation of elite Soviet Athletes. Technical Report #1012-62, Moscow: All-Union Research Institute of Physical Culture.
Darkhorse on 02-14-2006, 06:38 PM
part 1: debunking the myths
The squat is, perhaps, the single best exercise for leg strength and development. Squatting significantly strengthens the muscles responsible for knee and hip extension: quadriceps, hamstrings, and glutes, as well as the smaller stabilizing muscles such as the torso musculature. The squatting motion and position is also the foundation for many other exercises, such as deadlifts, Olympic lifts, and even every day lifting tasks. I think it is a very worthwhile task to learn how to squat, and anyone who can get out of a chair can do it. It has benefits not just for your strength, but for balance, confidence, daily-life strength, cardiovascular capacity, and active flexibility.
Problem is, the squat is often taught incorrectly, and it's stigmatized as difficult and dangerous. People warn that it is bad for your knees and back, inappropriate for beginners (or anyone not a male collegiate athlete), too hard to learn, blah blah the sky is falling, etc. So, let's go through all the scary things we've heard about squatting, to debunk them one by one.
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 full 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
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.
why are leg extensions hard on the knee joint?
To understand why this is, it is helpful to understand the concept of shear. Shear in this case just refers to a horizontal force on the joint. Imagine two cans stacked on top of one another, and imagine that a piece of masking tape joins them. Then, imagine what happens if you hold the top can still while you push the bottom can to one side. Eventually that tape will snap. This is a simplistic description of what happens to the knee joint in a leg extension.
Here is a simple diagram that attempts to explain the difference between the squat and the leg extension. The black lines represent the thigh bone, shin bones, and knee joint (black circle). In a squat, as shown in the figure on the left, your feet are on the ground (hopefully), and the force of the load is transmitted downwards, along the length of the bones. In a leg extension machine, there is a pad against the front of your shin or ankle, and you press against it to move the weight. The foot swings upward in an arc. Thus, as you can see in the figure on the right, the pressure is coming across the shin bones, not along their length. This creates the problem in the knee joint as the shin is pressed backwards.
Leg extensions do have their place, usually in rehab. If the leg extension machine is used, it is wise to use a smaller range of motion, perhaps the top third of the movement (from slightly bent to fully straight leg), and light weight.
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....
Darkhorse on 02-15-2006, 06:12 PM
But..How FAR Down?!
The second one is what the mortar men in my unit call, "Firing For Effect!"
Last edited by Darkhorse; 02-15-2006 at 06:39 PM..
Dr X on 02-15-2006, 07:21 PM
That pic looks like Sgt. Slaughter
EricT on 02-16-2006, 12:15 PM
I've begun to just assume most people are talking about parallel or above when they say squat. It's an epidemic.
I started out doing A2G's. Two things I always did was A2G's and kicking and punching the heavy bag. NEVER had a knee problem. Know when I did get an injury?
Right after I decided to squat parallel for a while. I had always went all the way down just because that's the way I thought it was done, not because I had any real knowledge at the time. But for a short time I got duped into squatting parellel out of the mistaken belief that more weight would equal better gains, period. I felt the pressure in my knees, which I had never noticed on A2G's.
The first time I started working out on the bag after doing those parallels for a while, I threw a kick and POP, there goes my knee. It gave me problems for quite a while. Coincidence? I think not.
I actually credit A2G's with making my knee pain free now.
|Currently Active Users Viewing This Article: 1 (0 members and 1 guests)|