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Performance Area => Article & Video Discussion => Topic started by: DamienZ on February 27, 2011, 07:08:56 am
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http://www.nsca-lift.org/HotTopic/download/Squat%20Depth.pdf (http://www.nsca-lift.org/HotTopic/download/Squat%20Depth.pdf)
The Biomechanics of Squat Depth
Brad Schoenfeld, CSCS
This paper was presented as part of the NSCA Hot Topic Series. All information contained herein is copyright of the NSCA. www.nsca-lift.org
The Biomechanics of Squat Depth 2
The squat is widely employed as a staple exercise in exercise programs, both for athletic and recreational populations. How- ever, significant controversy exists as to optimal squat depth, both in terms of safety and muscular activity. This paper will seek to clarify these issues, and provide recommendations for performance.
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 con- trol 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. In a study using a knee ligament arthrometer to test nine measures knee stability, Chandler, et al. found that male powerlifters, many of them elite class, demonstrated significantly tighter joint capsules on anterior drawer tests compared to controls (3). Moreover, both the powerlifters as well as a group of competitive weight lifters were significantly tighter on the quadriceps active drawer tests at 90 degrees of knee flexion than control subjects.
Contrary to Klein’s hypothesis, ACL and PCL forces have been shown to diminish at higher degrees of knee flexion. Peak ACL forces occur between 15 – 30 degrees of flexion, decreasing significantly at 60 degrees and leveling off thereafter at higher flexion angles (7, 11, 16). PCL forces rise consistently with every flexion angle beyond 30 degrees of knee flexion, peaking at approximately 90 degrees, and declining significantly thereafter (10). Beyond 120 degrees, PCL forces are mini- mal (12).
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.
It can be argued that ligamentous injury risk during squatting is actually greatest in the parallel squat—the position where PCL forces are at their apex. However, the magnitude of maximal posterior shear during squat performance (approximately 2,700 N) is well below the strength capacity of a young, healthy person’s PCL, which is estimated to exceed 4,000 N (5). It should also be noted that regimented resistance training confers an adaptive response in connective tissue, increasing its strength capacity (1). A stronger ligament serves to improve tolerance to load, thus further reducing the prospect of injury.
The greatest risk for injury during deep squatting would theoretically be to the menisci and articular cartilage (5, 10). Tibio- femoral compressive forces have been shown to peak at 130 degrees of knee flexion where the menisci and articular cartilage bear significant amounts of stress (14). Deep squats may also increase susceptibility to patellofemoral degeneration given the high amount of patellofemoral stress that arises from contact of the underside of the patella with the articulating aspect of
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The Biomechanics of Squat Depth 3
the femur during high flexion (6). However, there is little evidence to show a cause-effect relationship implicating an in- creased squat depth with injury to these structures in healthy subjects.
Squat depth has been shown to have a significant effect on muscular development at the hip and knee joints, particularly with respect to the gluteus maximus (GM). Caterisano, et al. demonstrated that while average muscle activity of the GM was not significantly different in both the partial squat (16.92 ± 8.78%) and parallel squat (28.00 ± 10.29%), it increased significantly during the full squat (35.47 ± 1.45%) (2). Similar results were shown for peak values, which displayed signifi- cantly greater activity during performance of the full squat as compared to lesser squat depths.
As opposed to the GM, squat depth has little effect on hamstrings involvement. Maximum hamstrings activity tends to oc- cur between 10 to 70 degrees of flexion, but the magnitude of variation in peak and mean torque is not significant between partial squats, parallel squats and full squats (4, 17, 19). This is consistent with the bi-articular structure of the muscle com- plex. Since the hamstrings function both as hip extensors and knee flexors, muscle length remains fairly constant throughout performance, providing a relatively even force output.
Muscular forces at the knee are largely produced by the quadriceps femoris, with muscle activity peaking at approximately 80 to 90 degrees of flexion and remaining relatively consistent thereafter (4, 19). This would seem to infer that squatting past 90 degrees is superfluous if the goal is to maximize the development of the quadriceps.
In conclusion, there is scant evidence to show that deep squats are contraindicated in those with healthy knee function. The decision as to how low to squat should therefore be based on an individual’s performance-oriented goals and considered in conjunction with any pathological issues that may be apparent. Those with PCL disorders should refrain from squatting below 50 to 60 degrees until the injury is fully healed. Disorders such as chondromalacia, osteoarthritis, and osteochondritis may also contraindicate the performance of deep squats. To optimize development of the gluteus maximus, squats should be carried out through their full range of motion. To target the quadriceps femoris, a squat depth of 90 degrees appears to be optimal.
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The Biomechanics of Squat Depth 4
References
1. Buchanan CI, Marsh RL. Effects of exercise on the biomechanical, biochemical and structural properties of tendons. Comparative Biochemistry and Physiology. Part A, Molecular and Integrative Physiology. 133(4):1,101 – 1,107. 2002
2. Caterisano A, Moss RF, Pellinger TK, Woodruff K, Lewis VC, Booth W, and Khadra T. The effect of back squat depth on the EMG activity of 4 superficial hip and thigh muscles. Journal of Strength and Conditioning Research. 16(3):428 – 432. 2002
3. Chandler T, Wilson G, and Stone M. The effect of the squat exercise on knee stability. Medicine and Science in Sports and Exercise. 21(3):299 – 303. 1989.
4. Escamilla RF, Fleisig GS, Zheng N, Barrentine SW, Wilk KE, and Andrews JR. Biomechanics of the knee during closed kinetic chain and open kinetic chain exercises. Medicine & Science in Sports & Exercise. 30:556 – 569. 1998.
5. Escamilla RF. Knee biomechanics of the dynamic squat exercise. Medicine and Science in Sports and Exercise. 33:127 – 141. 2001. 6. Escamilla RF, Fleisig GS, Zheng N, Lander JE, Barrentine SW, Andrews JR, Bergemann BW, and Moorman CT. Effects of technique variations
on knee biomechanics during the squat and leg press. Medicine and Science in Sports and Exercise. 33:1,552 – 1,566. 2001. 7. Kanamori A, Woo SL, Ma CB, Zeminski J, Rudy TW, Li G, and Livesay GA. The forces in the anterior cruciate ligament and knee kinematics
during a simulated pivot shift test: A human cadaveric study using robotic technology. Arthroscopy. 16(6):633 – 639. 2000. 8. Klein K. The deep squat exercise as utilized in weight training for athletes and its effects on the ligaments of the knee. JAPMR. 15(1):6 – 11.
1961. 9. Li G, Zayontz S, DeFrate LE, Most E, Suggs JF, and Rubash HE. Kinematics of the knee at high flexion angles: an in vitro investigation. Journal
of Orthopaedic Research. 27(6):699 – 706. 2004. 10. Li G, Zayontz S, Most E, DeFrate LE, Suggs JF, and Rubash HE. In situ forces of the anterior and posterior cruciate ligaments in high knee
flexion: an in vitro investigation. Journal of Orthopaedic Research. 22(2):293 – 297. 2004. 11. Li G, Rudy TW, Sakane M, Kanamori A, Ma CB, and Woo SL. The importance of quadriceps and hamstring muscleloading on knee kinematics
and in-situ forces in the ACL. Journal of Biomechanics. 32(4):395 – 400. 1999. 12. Markolf KL, Slauterbeck JL, Armstrong KL, Shapiro MM, and Finerman GA. Effects of combined knee loadings on posterior cruciate ligament
force generation. Journal of Orthopaedic Research. 14(4):633 – 638. 1996.
13. Meyers E. Effect of selected exercise variables on ligament stability and flexibility of the knee. Research Quarterly. 42(4):411 – 422. 1971.
14. Nisell R, and Ekholm J. Joint load during the parallel squat in powerlifting and force analysis of in vivo bilateral quadriceps tendon rupture. Scandinavian Journal of Sports Sciences. 8: 63 – 70. 1986.
15. 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.
16. Sakane M, Fox RJ, Woo SL, Livesay GA, Li G, and Fu FH. In situ forces in the anterior cruciate ligament and its bundles in response to anterior tibial loads. Journal of Orthopaedic Research. 15(2):285 – 293. 1997.
17. Signorile JF, Weber B, Roll B, Caruso J, Lowensteyn I, and Perry AC. An electromyographical comparison of the squat and knee extension exer- cises. Journal of Strength and Conditioning Research. 8:178 – 183. 1994.
18. Steiner M, Grana W, Chilag K, and Schelberg-Karnes E. The effect of exercise on anterior-posterior knee laxity. American Journal of Sports Medi- cine. 14(1):24 – 29. 1986.
19. Wilk KE, Escamilla RF, Fleisig GS, Barrentine SW, Andrews JR, and Boyd ML. A comparison of tibiofemoral joint forces and electromyograph- ic activity during open and closed kinetic chain exercises. American Journal of Sports Medicine. 24(4):518 – 527. 1996.
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http://www.apec-s.com/Deep%20Squats.pdf (http://www.apec-s.com/Deep%20Squats.pdf)
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point?
bbl sleep
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point?
bbl sleep
well, decide on your own... :ninja:
My take is that a healthy athlete should be able to squat deep and sit in a deep squat comfortably. It's not only about strength/power but also about mobility, flexibility, balance and coordination...
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point?
bbl sleep
well, decide on your own... :ninja:
My take is that a healthy athlete should be able to squat deep and sit in a deep squat comfortably. It's not only about strength/power but also about mobility, flexibility, balance and coordination...
i think we need to define "athlete" here.. are we talking about an olympic lifter athlete or a basketball/football/etc athlete? because, for the latter, "balance + coordination + knee stability" is going to be best obtained through reactive/dynamic movements specific to their sport, squatting (any form) doesn't even come close.
As for flexibility, that level of flexibility isn't even needed for most sports. Having too much flexibility can be a bad thing, that's a really hard issue to discuss because it's so individual-specific. If I use myself as an example, too much flexibility/mobility work makes me perform worse -> when i'm "tight", I descend into my plants and just rocket right out, I can feel the tension.. if i'm "too flexible" due to too much stretching/mobility work, I feel like mush and I feel some "collapsing" going on in the plant. The same issue applies to my explosive bball dribbling, sprinting, etc.. If I stretch my quads, I perform worse.
One of the major issues with deep squatting is meniscus issues, regardless of any of the benefits you mentioned, meniscus issues are a real concern. That "shock absorbing tissue" is stress intensively during reactive/explosive/sport movements, taxing it further and in such "extreme joint roms under tension" doesn't sound like the smartest thing to me if you're a non oly lifter... If you're an oly lifter, then it's very smart, you'd want to get strong at those roms because it's specific to your sport, not doing so would increase injury risk.
I can't think of many sports where deep mobility is necessary or beneficial.. Plenty (i'd say a majority) of the most powerful athletes on earth don't have the mobility to squat ATG properly. It's rare when you find someone who is freaky-powerful with leverages beneficial to RVJ/sprint/etc that has perfect ATG squat form/mobility, extremely rare. I worked with over 30 NFL combine athletes one year and the vast majority of them were tight. Out of the two most powerful athletes, 4.39 40 vs 4.31 40, one was insanely tight, one was insanely flexible. Both had a shitload of muscle and were so strong it was ridiculous. One could ATG squat perfect (being 5'6), the other could only hit half with good form (being 6'1 or so).
Bottom line, individual differences highly influence whether or not someone should be going deep or not, so making a blanket statement about squat depth doesn't take into account those individual differences. For the vast majority of athletes interested in VJ/sprinting, going deep is very unnecessary because those athletes, who are naturally drawn to these performance events, have more ability to progress with half squatting due to leverages/mechanical advantage at those joint angles.
Beyond any of that, half squatting (slightly above parallel, NOT PARALLEL) is 100x more specific to vert/power based athletic movements than is deep squatting.
pc
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it's funny that you feel attacked by me posting those articles!
i just saw them in a blog from bret contreras and i thought it was interesting to read what is going on in a deep squat.
i just posted them here for a discussion and not to attack you or anybody else to defend why they don't squat deep...
but still, do like boevski :ibsquatting:
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Beyond any of that, half squatting (slightly above parallel, NOT PARALLEL) is 100x more specific to vert/power based athletic movements than is deep squatting.
Isn't weighttraining always just GPP for the non weightlifter-athlete?
At the end it shouldn't matter how the strength was obtained...
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Just because it's GPP doesn't mean they are equally effective. I mean there is no thick black line right between specific training and GPP lol, i view it more as a "gradient" of sorts. But still, I just like deep squatting because it feels better for me. Maybe in the future when I stall on deep squats ill hit an intense partial squat peaking cycle.
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Beyond any of that, half squatting (slightly above parallel, NOT PARALLEL) is 100x more specific to vert/power based athletic movements than is deep squatting.
Isn't weighttraining always just GPP for the non weightlifter-athlete?
At the end it shouldn't matter how the strength was obtained...
so then why would it matter if strength is obtained in a deep squat vs half squat?
checkmate
goodnight
do not pass go
do not collect $200
pc.
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Beyond any of that, half squatting (slightly above parallel, NOT PARALLEL) is 100x more specific to vert/power based athletic movements than is deep squatting.
Isn't weighttraining always just GPP for the non weightlifter-athlete?
At the end it shouldn't matter how the strength was obtained...
so then why would it matter if strength is obtained in a deep squat vs half squat?
checkmate
goodnight
do not pass go
do not collect $200
pc.
Hahaha, I bet adarqui had sweet dreams after this.
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Beyond any of that, half squatting (slightly above parallel, NOT PARALLEL) is 100x more specific to vert/power based athletic movements than is deep squatting.
Isn't weighttraining always just GPP for the non weightlifter-athlete?
At the end it shouldn't matter how the strength was obtained...
so then why would it matter if strength is obtained in a deep squat vs half squat?
checkmate
goodnight
do not pass go
do not collect $200
pc.
deep squats seem to be healthier, less risky and more bang for your buck than half squats. you're always talking about your onees, hips and spinal compression. full squat is actually good for your knees, could gradually increase hip mobility (good hip mobility = healthier lower back) and as u can't take as much weight on a half squat there's less spinal compression.
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Beyond any of that, half squatting (slightly above parallel, NOT PARALLEL) is 100x more specific to vert/power based athletic movements than is deep squatting.
Isn't weighttraining always just GPP for the non weightlifter-athlete?
At the end it shouldn't matter how the strength was obtained...
so then why would it matter if strength is obtained in a deep squat vs half squat?
checkmate
goodnight
do not pass go
do not collect $200
pc.
deep squats seem to be healthier, less risky and more bang for your buck than half squats. you're always talking about your onees, hips and spinal compression. full squat is actually good for your knees, could gradually increase hip mobility (good hip mobility = healthier lower back) and as u can't take as much weight on a half squat there's less spinal compression.
why does any of that matter when you defeated your own argument?
I don't see how deep squats seem to be healthier or are less risky, especially from the studies/review you posted. half squat is just as good for the knees as deep squat (with less meniscus damage risk). Less spinal compression isn't an issue, landing from jumps is more stressful. Occasional rounding/butt wink while going ATG is an issue. The meniscus concern the study cited, is an issue. The extra load you can lift on a half squat is no issue for the spine, you have more leverage in that position.
my hip mobility is fine specific to my sport, I have no need for "deep hip mobility", you mentioned taking a shit on the live chat, well i'd just go onto my toes and I wouldn't have barbell weight on my back.
deep squatting has less transfer than half squatting has, in terms of athletic movement.. but you don't care about that, it's GPP right? so then it doesn't matter at all and this entire thread is pointless.. bottom line get freaky strong deep or freaky strong half, it doesn't matter one bit.
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honestly from my perspective on a single rep vertical jump, especially standing vertical jump, a squat is like a special strength exercise, not just a general exercise, so it makes a lot of sense to do half squat from that perspective.
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Well yeah, I consider full squats a GPP exercise and half squats more of a SPP exercise, since they are more specific to jumping and you can play with the load a bit.