Squat: Depth explained? A full technique analysis

There are a lot of myths and fallacies regarding squatting. So this articles aim is to try and educate people on the technique involved in barbell squatting!!

So firstly, I mention technique analyses… but what does this really mean? Well according to Lees, (2002) it is simply a method of analysing and understanding the ways in which movements are performed. This can be done through the collection of data and interpretation from scientists and coaches together. This can be done in 3 ways, qualitative, quantitative or predictive, but I won’t bore you all with the ins and outs. Let’s get onto the squatting!

Well, no I lied slightly, one last point we need to consider is how we learn movement patterns, especially complex, multi-joint motor patterns such as the squat. Escamilla, (2001) describes the squat as a closed chain kinetic movement, because the lower limbs do not love in relation to the immoveable surface of the floor. So a brief intro into a few theories of how we learn movement patterns…

Schmidt (1975) proposed the information processing theory of skill acquisition. 10 years later in 1985, Forssberg proposed the neuromaturational theory. However, now the main theory researched is the constraints led approach (Newell 1986). In this paper, Newell (1986) describes a constraint as, ‘a characteristic of an individual, task or environment that either facilitates or restricts.’ The constraints led approach differed from the others at the time because it looks into Bernstein’s (1967)(cited in Handford et al, 1997) degrees of freedom problem and describes how the complexity of multi joint movements can be affected by the environment, this contradicts some of the main points in both Schmidt’s (1975) schema theory and also Adams (1971) closed loop theory as both of these neglect the role of environment opposed to the minds motor ability to perceive and mitigate complex movements (Handford et al. 1997). Newell (1986) states that, constraints can be found in 1 of 3 places; the organism, the environment or the task requirements. Davids et al. (2000) explains that the key to success is to master each of these 3 constraints outlined by Newell (1986).

Now, I want to talk about setting up for the squat, your first consideration for technique is actually the bar placement upon the back. Many muscular bodybuilders will choose the rest the bar slightly lower down on the lower region of posterior deltoids and inferior traps, as this is well built up and can allow deeper squats as the centre of gravity is further back through the heels, however many people cannot do this because of discomfort or lack of flexibility through the shoulders. In this case the bar should be rested higher up the traps but still away from the neck. Hand position can also vary greatly with many top powerlifters holding the actual sides of the weights plates themselves, this is NOT advised, as it promotes ‘sloppy’ form with minimal stability and relies a lot on motor programmes and balance, only experience lifters and athletes should use this technique. Hands should be slightly wider than shoulders with elbows low, keeping the lats tensed and arms in tight to the body. This allows for greater tension throughout the whole body and stabilisation of the back and core. After this comes the de-racking of the bar. The feet should be directly under the bar, heels planted firmly and knees slightly bent, the weight should be vertically lifted before stepping away from the stands or rack (I doubt many people reading this would be squatting off a monolift). Feet should then be set at comfortable distance apart (Varies dependant on aim of the squat) and the angle the feet point out should also be set (again, vary dependant on aim of the squat) for me I find a stance slightly wider than shoulders with feet pointing outwards about 15-20 degrees is optimal. Before each squat a deep breath should be taken and held in to maximise thoracic and intra abdominal pressure. Once the final rep is completed don’t think you’re out of the woods, racking the bar is equally as dangerous. Keeping everything tight you should step back forwards into the rack/stands, check you are lined up correct with feet equally placed and weight distributed and bend at the knees to rest the bar back in place. Final note here comes from what I have witnessed at my own gym… DO NOT SQUAT BACKWARDS IN A RACK ! The de-rack should be a backwards step and re racking forwards step. It is common sense, re racking a bar stepping backwards when your legs are fatigued is just plain stupid and dangerous!

N.B. The majority of the rest of this article is lifted from a research study I did myself along with two fellow colleagues whilst at university (Sam Ismail and Adam Oliver). This paragraph will explain the protocol we designed and followed, if you are not interested in this part please just skip to the next paragraph; Method: Participants: 2 Male participants were used, both undergraduate students at Nottingham Trent university in their 2nd year. They were classified as novice and expert. The expert was classified as an expert as he had been coached and competed in UKPLF (United Kingdom powerlifting federation) competitions for the past 3 years whereas the novice had never done barbell squats before but was familiar with the concept via visual aiding around his local gym. The participants mean (±SD) age, (years) height, (cm) and body mass (kg) were 20 ± 0.0, 182.8 ± 3.5 and 89 ± 1.5 respectively. Both participants had been fully briefed as to what was expected from them and signed written consent forms and full health screening questionnaires prior to the study. Procedure: The video recording was done in the Biomechanics laboratory suite at Nottingham Trent’s Clifton campus. The barbell used was a 20kg Olympic regulation barbell. A digital video camera (Canon FS306) was placed on a tripod pre-set at a height of 120cm and perpendicular to the participant’s sagittal plane along their coronal plane (also called the frontal plane). The camera was setup here as the coronal plane of motion was where the measured variables would be moving. The camera was situated 7m away from the movement to minimise any effects of perspective error. The shutter speed was 1/1000 with a sampling frequency of 25 Hz. An aperture of f/8 was chosen to help accuracy when digitizing the data. As advised by Bartlett (2007) the performer was recorded against a dark background to improve the visibility of the retro-reflective markers used for digitizing. A calibration frame was used in every sample made up of two 1m ruler sticks in a cross formation showing 1m horizontally and vertically, this was used to produce a scaling factor for on screen. 6 retro-reflective markers were placed on pre-determined anatomical landmarks on the right hand side of the participant so that specific joint angles could be measured throughout the movement. (Bartlett, 2007). These were placed, (from top to bottom) on the; Acromion process, Iliac crest, Greater Trochanter, Lateral epicondyle of femur, Lateral malleolus and the 5th Metatarsophalangeal joint. As shown below. Following a personal warm-up, each participant performed their 10 squats.

The location of these markers was used to later calculate the angles across the hip/trunk, the knee and the ankle. These 3 angles were the 3 variables to be compared and discussed in detail.

Mansfield (2003) describes 3 phases to a recognised squat. The descending phase, the ‘sticking point’ (For UKPLF regulation competitions, past parallel, i.e. the greater trochanter is lower than the lateral epicondyle of the knee, but we will visit this point in a moment) and the ascending phase.

Wertenberg (1996) suggested that, ‘the lower the height of descent during the squat, the greater the compressive force that is applied to the knee, requiring a greater exertion of force for the ascending phase of the squat’. This is why novice squatters do not adhere to powerlifting regulations in terms of the depth of their squats. Escamilla (2001) states that people new to squatting will not have the stability or force production in their knee joint capable of going as deep compared to those people who regularly practice the technique and have built up the relevant anatomy. Furthermore it recommends that people new to squatting continue with the ‘half-squat’ (just above parallel) to build up musculature and schema before attempting the deep squat (beyond parallel) because of the extra force production needed and the risk of patellofemoral pain it can cause to a novice if they are not stable throughout the movement, leading to inversion at the knees which in turn puts extra strain through the quadriceps tendon, lateral/collateral ligaments and other cartilaginous and soft tissues surrounding the knee joint.

Schoenfeld, (2010) states that the talocrural joint in the ankle is responsible for plantar-flexion and dorsiflexion. This is a main difference between novice and expert squatters as shown by Beard (2001) who examined flexibility in the lower limbs of novice squatters. He found average dorsiflexion to be 10±2 degrees. He stated that in order for the feet to be firmly planted and not have ‘heel lift’ (which is common amongst novice squatters) and maintain instersegmental stability the performer must have around 15±2 degrees of dorsiflexion. A 5 degree difference, however he later states that practicing this movement would increase dorsiflexion from the talocrural joint and hence how expert performers can reach over this 15 degree threshold.

My research backs this up perfectly,  (Below)showing the clear difference in flexibility around the talocrural joint between the novice and expert. The expert has an average range throughout the movement of 28.4 degrees whereas the novice is only 11.78 degrees. This is most noticeable around the bottom of the curve for the expert squat reaching around 80 degrees at ‘the sticking point’. This is a visual explanation as to why novices produce the ‘heel lift’ previously mentioned.

To the left,  demonstrates how a novice squat does not reach as lower depth as the knee angle range is only 84.8 degrees compared to the expert’s range of 101.1 degrees. This must fluctuate at the bottom of the squat because for a higher value at the top of the squat hyperextension of the knee would have to occur to create an angle greater than 180 degrees. It also shows a shorter time period for the duration of the squat with no pause at ‘the sticking phase’ which would also make it an illegal squat. I will talk more in a moment about how this affects the torque through the cartilaginous structures of the knee.

The hip joint is the final variable to be considered in this analysis, Schoenfeld (2010) describes it as ‘a ball-and-socket joint, comprising the articulation between the head of the femur and the acetabulum of the os coxae.’ Hemmerich et al. (2006) reported a mean hip range of motion during novice squatting to be 95 ± 27 degrees. Showing that novices may not complete full deep squats that experts can because of a lack of flexibility, he later concludes that flexibility training can overcome this deficit.

Again my research concurs, showing a 6.43 degree difference at the deepest point of each squat. More importantly from the above data however is the curve seen in the graph, illustrating an eratic lumbar back posture from the novice, vs a smooth controlled curve of the expert. This is down to intersegmental stability and is often why on heavier squats people use weights belts, which can increase intraabdominal pressure and reduce spinal loading, when used in conjunction with the Valsalva manoeuvre. However I will write a separate article on the pros and cons of weights belts at a later date!

Right so lets put this data into some contexts regarding possible dangers of squatting with poor form.

Escamilla (2001) makes an anecdotal statement that novice squatters do not have the stability in the knee to go past parallel. The data above shows the novice squatter’s average total depth was above the 90 degree threshold by 2 degrees whereas the expert performer was 12 degrees below the threshold on average. Escamilla further goes on to explain that this could be down to motor programmes too, in the fact that a novice has never experienced that level of flexion at the knee and it would be unsafe to do so as it could compromise the laxity of the posterior cruciate ligament.

However, Fry et al (2003) show that the ‘heel lift’ employed by novices actually saves them from possible knee damage. This particular study found that where the knee translates further anteriorly than the toes, greater shear forces were applied through the knee joint, subsequently the novice performers ‘heel lift’ kept the knee over the feet and decreased the forces through the knee and reduced chances of patellofemural or patellotibial pain. The knee torque for the expert was 150.1 ± 50.8 N.m. whereas the novice was 117.3 ± 34.2 N.m. Wertenberg (1996) argues that this however may have nothing to do with the training status but merely the depth of squat achieved, as he states that the lower the depth of the squat, the greater the loading on the knee joint apart from the one anomaly where maximum force through the knee is found at parallel where there is a crossover of musculature and ligament laxity is maximal. What also isn’t mentioned here is the actual weight of the squat… the greater the weight obviously the greater the force will be, meaning that the experts forces are clearly going to be greater, however they will also have much better musculature to stabilise and cope with the demand, therefore although they have a greater strain, they are less likely to get hurt, because as a ratio of strain to stabilisation they are better equip than the novice.

Bazrgari (2006) shows why correcting lifting technique of novices is paramount, with a study done on stooping vs. squatting in relation to lower back pain. The study showed a difference of 800N in compression of the spine and 200N of shear loading force when poor technique was used compared to proper squat technique carrying the same amount of mass. With this in mind it is paramount to intervene and aid the novice’s performance.

It is fair to say that less skilled/experienced performers are more inclined to be in the co-ordination stage of learning according to Newell (1986) whereby a temporary fixation of the degrees of freedom occurs, as a direct result of this movements about the joint tend to be restricted (Handford 1997).

Commands such as, ‘sit down into the squat’, ‘weight back’, ‘shoulders back and chest out’, ‘weight through your heels’ are all verbal instructions that focus the attention of the performer into key aspects of the squat (Al-Abood et al. 2001). Bell & Hardy (2009) add to this stating that a distal external focus reaps even greater benefits to the performance. External foci are used in squatting by many coaches, the most common is telling the performer to look exaggeratedly upwards above their normal eye line, this gives a distal external focus and also helps keep back posture aligned.

With all this in mind and relating back to Eliots video, from my educated opinion, his squatting technique was absolutely fine, and there was no reason to worry about the depth and links to knee injuries. The original video can be seen below.

https://www.youtube.com/watch?v=LInW0B4U_Dg

Many thanks for reading this article and I hope you found it helpful and informative !!

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