Monster: Biomechanics of squatting
Biomechanics of squatting: How to avoid injury
Squatting has become the go-to exercise for most gym goers, but unfortunately, it is not as simple as we would like. Walking into any commercial gym, there will be at least three guys and girls squatting with horrific technique, slowly counting down the days until a blown disc or career-ending knee pain.
Even observing some of the professional fitness models’ and physique competitors’ techniques, subtle but dangerous errors can be identified, which leads to the question: Why are some coaches teaching this simple movement incorrectly?
When done correctly, the squat is a safe and highly effective way of training nearly every muscle in the body. Squatting is not just a strengthening exercise – it incorporates a number of different bodily control systems. As you unrack the barbell, it becomes a freely moveable object, meaning you have to stabilise it.
Perceived instability forces the neurological system to coordinate smaller stabilising muscles that lay close to joints. Learning to co-ordinate these small integral muscles can prevent future injuries by maintaining joint health, and is the main reason why over training the leg press machine is a bad idea. Leg pressing is a unidirectional movement (you can only push one way), so you only train the ‘prime mover’. Too much strength in the prime mover can theoretically pull your joint out of its central position (centration) and lead to micro injury. This is why focusing on these smaller stabilising muscles is so important for longevity in training.
Unfortunately, throughout our life, we all pick up bad movement habits: mid back slouching, pulling shoulders forward, anterior pelvic tilt, pronation of the foot, knock knees – we could go on. These postural faults show us that our bodies are innately lazy. We will always pick the path of least resistance.
When developing any high level motor skill, we pick up on subtle technique errors by consistently auditing movement patterns, with the view of progressing towards increased efficiency. Most of us need to take an ego check and start over again if we want to be successful in skill acquisition.
Centre of mass and the mid foot
Understanding what we should be doing while squatting means we need to understand the behavior of the weight in relation to gravity. Once you understand this, you will be able to effectively coach yourself. First we need to get some terminology out the way:
- Centre of mass (COM): the area in which all the mass focuses. As the barbell becomes heavier the COM will become considerably lower.
- Mid foot: this is the sweet spot, the exact mid point between your toe and your heel.
- Fulcrum: the axis of rotation.
- Bar path: the movement of the bar as viewed from the side (most commonly).
There are two rules within barbell training:
- The COM stays over the mid foot
- The bar path should be vertical at all times
High bar vs low bar
The main issue for casual gym goers is bar placement. Our natural instinct is to put the bar high on the shoulders which, as you lower into your squat, means the weight will deviate significantly from the mid foot. This creates a huge shear force across the spine and a large space between the fulcrum and the weight – most probably a sore low back too.
LOW BAR MECHANICS
SHEAR FORCE FROM TOO HIGH BAR PLACEMENT
PROPER HIGH BAR MECHANICS
Looking at the two pictures, we can see by placing the bar further down the back, we can keep the COM much closer to the mid foot. This creates a more fluid vertical bar path, bringing the fulcrum closer to the COM and increasing the amount of weight that can be lifted.
To do this:
- Set up low bar
- Place the rack at chest height
- Place the bar on the top of your posterior delt shelf
- Squeeze your hands as close to your back as possible
- Squeeze your elbows towards your body, then pull them down
- Take a deep breath into your stomach
- Unrack the weight, take maximum three steps back (left, right, left)
- Breathe further into abdomen while pushing feet away from each other (spreading the floor)
- SQUAT – below parallel or not at all.
This is not inclusive, so please check our the sources below for more guidance:
- Starting Strength by Mark Rippetoe startingstrength.com
- Juggernaut Training Systems – jtsstrength.com
- Strength is Never a Weakness blog – strengthtrainingforyou.blogspot.com
- Sean Ryan – personal trainer based in Belfast
Common mistakes and biomechanics
Your back is not particularly happy when being forced to bend under heavy load. Spines (when loaded) prefer to be locked in a neutral position. Your spine is made of vertebrae, separated by discs, with small facet joints located posteriorly. When spinal alignment is maintained, the back is an incredibly resilient structure, however, when even the smallest “kink” appears, we predispose ourselves to injury. If you are lifting any type of weight with a bent spine, you are most probably increasing the chance of a serious spinal complaint (for most beginner/intermediate level lifters, Chinese weightlifting team seem to be including a lot of loaded spinal flexion).
Breathing into your abdomen
Imagine an empty cardboard box, easy to crush when you push on it. Now inflate a balloon in it, almost impossible to crush now?
Our lumbar spine is a sultry projection that joins the pelvis to the rib cage. It looks incredibly precarious in contrast to the large pelvic basin and 360degree bony structure of the ribcage. However, the lumbar spine can be stabilised a lot like the cardboard box. When you take a deep breath into your abdomen, you create intra-abdominal pressure (IAP) which is similar to the inflation of a balloon in a cardboard box. The deep breath fills the abdomen and pushes outwards against the core muscles, creating an incredibly strong lumbar spine. This is why the inclusion of a belt at heavier weights is something worth investigating. The belt creates even more force for the IAP to push against. I do not believe it creates any weakness or atrophy of these muscles (articles).
Very common in females (Instagram models particularly), allowing your back to over extend at any point will create a “hollow back” appearance. Keeping your chest up is an unhelpful cue as it encourages these athletes to maintain an arched back. By loading in extension, you push the facet joints together (apposition) often leading to painful joint inflammation and fixation, which is often felt in the mid back area. You also reduce your ability to fill the abdomen with 360 degrees of pressure as your rib cage has become dissociated from the pelvis.
Butt wink – probably the single biggest squat fault and is highly debated. As with everything you read on the internet, take any advice with a pinch of salt. There is, in reality, no one way to do things. With my knowledge of spinal mechanics (more correctly Stuart McGill’s knowledge of spinal mechanics), we can only give an opinion. The spine is being loaded and asked to cyclically undergo flexion/extension with butt winks. As we know, the spine is made to move as a whole and segments are made to distribute movement across large areas.
The butt wink creates movement focused on the lower lumbar spine alone (coincidently the most common area to blow a disc). This constant and repetitive flexion extension cycle is thought to chip away at the outer layers of a disc, theoretically predisposing to disc injury. So, don’t do it!
All opinions are my own and do not represent secondary parties.
Luke Thomas Neal
North Down Chiropractic
34 Grays Hill, Bangor
By Dr Luke Thomas Neal MChiro, from North Down Chiropractic