Science Meets Fitness & Exercise
Partial or Full Squats?
The barbell squat is one of the most accepted and yet maligned exercises in the sphere of resistance training. Criticised for its injurious potential and yet exulted as being one of the greatest mass and strength builders available to the aspiring bodybuilder or sports participant. Debates about the effectiveness of the movement and how it should be performed are still at the forefront of gym discussion and scientific scrutiny. So in order to make a knowledgeable judgment as to how and where to use this movement you must have some understanding of the ‘assertions’ that are made regarding the exercise; and what is scientifically demonstrable; or indeed, what is just gym myth. Herein, we shall now look at the barbell squat and attempt to answer some of these complex but pertinent questions.
The article will cover several areas of significance to the barbell squat and will endeavour to provide a qualified overview of these factors. The factors that will be discussed are:
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Should you ‘full squat’ or not?
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Barbell squat – Anabolic stimulation
Tom Platz - Took Leg Development to a New Level
In 1961, a researcher named Dr. Karl Klein, who already had an inherent predisposition to criticize full squats, carried out a piece of research that involved testing Olympic lifters for knee ligament stability. When compared against a control group and with subsequent cadaver research; he surmised that the Olympic lifters had an increase in the slackness of the collateral and ACL ligaments of the knee. With this in mind he recommended that individuals should not go below parallel when performing the barbell squat. The fallout of this recommendation was that the United States military, the New York School Board and the American Medical Association all took this research so seriously that the demise of the full squat began. The ripple effect of this research has carried through to modern times despite the fact that many studies have contradicted these original findings and further,
‘Dr. Karl Klein’s study at the University of Texas in 1961 was a poorly designed and badly conducted mess that has never been replicated and has been successfully rebutted many times. Klein concluded that below parallel squats produced “loose” knees, although no other training protocol was evaluated for comparison, no other tester administered the measurements, and all the data was biased by pre-test questioning of the subjects’ (Rippetoe, 2007)
So with that in mind what would be the recommendations for squat and knee flexion angle if knee damage is to be avoided. Let us first look at the supporting structures of the knee joint i.e. the knee ligaments and stability. Many research endeavours have addressed the premise that full squats are a risk factor in respect of knee stability. Research of course usually always has an element of contradiction but let us first look at studies that have shown positive result in terms of knee stability and employment of the squat exercise movement.
Chandler T.J., Wilson G.D. and Stone M.H. (1989) carried out a large study which involved 100 male and female college students. They carried out 9 tests regarding knee stability after an 8-week squat training program and determined that ‘no effect of squat training on knee stability was demonstrated in any of the groups tested’. Their study looked at full and half squats.
Panariello R.A., Backus S.I. and Parker J.W. (1994) studied the effect of the squat exercise on the anterior-posterior knee translation of professional football players. Thirty-two subjects with normal knees participated in a 21-week off-season training program. The subjects performed power squat exercises with barbell loads of 130% to 200% body weight two times per week. The knees of each subject were tested by a single examiner with a knee ligament arthrometer before the training program and at 12 and 21 weeks. As a result of this study, the researchers arrived at the conclusion that there were ‘no significant increases in anterior-posterior tibiofemoral translation in athletes using the squat exercise as part of their off-season training program’.
The other main argument in terms of knee damage suggests that the compressive forces observed in the full squat technique might have degrading effects to structures such as the articular cartilages and the menisci which are heavily involved in the weight bearing process.
However, Hartmann H, Wirth K, and Klusemann M. (2013) asserted that the opposite could be the case and that full squats might positively benefit these compressive structures, stating that,
'Many studies have illustrated that full squats do not cause significant instability in the knees and might even be beneficial in stopping injuries occurring.'
Hartmann et al (2013). Chandler T.J. et al (1989) and Panariello R.A. et al (1994)
Hartmann (9913) stated that, ‘Concerns about degenerative changes of the tendofemoral complex and the apparent higher risk for chondromalacia, osteoarthritis, and osteochondritis in deep squats are unfounded. With the same load configuration as in the deep squat, half and quarter squat training with comparatively supra-maximal loads will favour degenerative changes in the knee joints and spinal joints in the long term’ Hartmann et al (2013).
Gullett J.C, Tillman M.D, Gutierrez G.M. and Chow J.W. (2009) after their study on front and back squats; stated that
‘the back squat resulted in significantly higher compressive forces and knee extensor moments than the front squat’.
But that statement does not inherently suggest these are damaging compressive or moment forces. They further go onto state that
‘Shear forces at the knee were small in magnitude, posteriorly directed, and did not vary between the squat variations’.
Their recommendations from this were that ‘results suggest that front squats may be advantageous compared with back squats for individuals with knee problems such as meniscus tears, and for long-term joint health’. But this study does not ‘clearly’ conclude that below parallel back squats are a significant issue where knee damage is a consideration.
Sahli S. et al (2008), suggested that
‘the half squat may be safe to use for quadriceps strengthening with very low potential loading on the anterior cruciate ligament (ACL)’.
But once again this is a very open-ended statement that does not offer clear constructive advice on other squat variations; or their potential benefits.
Escamilla R.F. (2001) stated that,
‘the parallel squat was not injurious to the healthy knee’. And further goes onto assert that, ‘For athletes with healthy knees, performing the parallel squat is recommended over the deep squat, because injury potential to the menisci and cruciate and collateral ligaments may increase with the deep squat. The squat does not compromise knee stability, and can enhance stability if performed correctly’.
The term ‘may’ in this statement is a little subjective and perhaps requires a little more clarification?
So should an individual full squat or carry out partial squats with respect to considerations of injury.
The consensus with regards to research is that full squats are a useful tool in the bodybuilding and sports specific training arsenal (Hartmann H, Wirth K, and Klusemann M. 2013; Panariello R.A., Backus S.I. and Parker J.W. 1994).
However, should a pre-existing injury already exist i.e. anterior cruciate ligament tears, then a partial or half squat might be advisable to strengthen the structures and muscles around the knee after recovery (Sahli S, Rebai H, Elleuch MH, Tabka Z, Poumarat G., 2008).
However, be aware that some studies have shown negative potential injurious aspects to squat performance, especially if the technique is not precise. (Fleck, S.J. and Falkel, J.E, 1986, Klein, K. 1961).
As a summary to this section on squats and the injurious implications let us consider the stance of the National Strength and Conditioning Association (NCSA). That being;
‘Some reports of high injury rate may be based on biased samples. Others have attributed injuries to weight training, including squat, which could have been caused by other factors. Injuries attributed to squat may result not from the exercise itself, but from improper technique, pre-existing structural abnormalities, other physical activities, fatigue or excessive training.’ NCSA (2012).
They further state that ‘Squats, when performed correctly and with appropriate supervision, are not only safe, but maybe a significant deterrent to knee injuries.’
In conclusion, it is our stance, based on all the information contained in this article that squats have been given a bad reputation and the majority of the scientific consensus seems to indicate that this bad reputation is unfounded. So employ the full squat into your routine but ensure that technique is clean and precise and that science not ego, dictates the poundage’s you employ.
MMA
They further and more importantly proceeded to state that,
‘The deep squat presents an effective training exercise for protection against injuries and strengthening of the lower extremity. Contrary to commonly voiced concern, deep squats do not contribute to increased risk of injury to passive tissues’. Hartmann et al (2013).
