I must admit over the past few years I have gone back and forth about it. I’m a fan of Coach Mike Boyle and his philosophies on the back squat and preference to single leg training and as a result I followed his lead and took the back squat out of my own personal programme as well as the majority of my athletes’ programmes.
However, as a coach myself I like the back squat for a variety of reasons and I missed coaching this fundamental movement pattern while my athletes missed ‘getting under the bar’. This past summer I reintroduced the back squat into my personal routine in addition to adding it to some of my athletes’ workouts; with good success.
When putting together this seasons S+C plan for one of the sports academy’s DO Training consult for; I decided to build this element in as part of the wider programme. But it’s all about understanding when it’s appropriate – I will only allow my athletes to load the back squat if they have adequate ankle and hip mobility, as well as being able to keep their torso upright, at a safe angle and they can ‘get low’ or ‘deep’. I programme a good mix of bi-lateral and uni-lateral exercises and consider them of equal importance.
So if you want to back squat and include it in your programmes, just make sure you can GET LOW and SQUAT DEEP!!! Here are some of the reasons why.
Firstly, for this article when we talk about a deep squatting we are talking about beyond 90˚ of flexion or beyond “top of thigh parallel to the floor”. So to clarify, a deep squat is in the range beyond 90˚ between the tibia/fibula and femur.
Athletes that participate in sports that involve jumping and running, such as volleyball and basketball,are seen to be at a greater risk of developing patellafemoral related injuries (4). For this reason many rehab specialists frown upon the use of deep back squatting, based on the rationale that it will only increase the force placed on the patellofemoral joint.
However, with increased flexion (depth in the squat) comes increased patellofemoral joint contact area. This increase in contact area distributes the patellofemoral joint reaction force over a greater surface area, and so maintains or even reduces patellofemoral joint stress as you get deeper in your squat. This could make the deep squat less of a factor in relation to patellofemoral injuries (10).
Although it is true that shear forces tend to increase with increasing knee angles, forces on both the ACL and PCL actually decrease at high flexion, in fact at higher flexion there is better stability and greater tolerance to load in the knee joint (1). It must also be noted that the peak forces on both the ACL and PCL during a squat are well below that of a healthy ACL and PCL strength capacity. The body will have an adaptive response to deep squatting which will increase the tensile strength of the knee joint ligaments and tendons, resulting in a reduced risk of ligament and tendon Injury (1).
There is a downside to the greater stability and tolerance to load, and that is; due to the increased compressive force at high flexion the menisci and articular cartilage are placed under increased stress (5). However, there is little evidence to show a cause and effect relationship of an increased squat depth with injury to these structures in healthy subjects.
When back squatting your quadriceps activity will tend to peak at 80˚-90˚ of knee flexion, so squatting past 90˚ won’t result in additional enhancements in quad development but it will ensure you are getting the most quad activation that you can with every repetition. However when you squat past 90˚ you will find that there is a significant increase in Gluteus Maximum muscle activity (2), which will help to give you a great looking, strong and powerful rear-end. Since the hamstrings functions both as hip extensors and knee flexors, its muscle length will remain fairly constant throughout squatting regardless of depth, this will provide a relatively even force output from 10˚ to 120˚ of flexion.
So why is ankle flexibility and mobility so important when deep squatting?
When ankle flexibility and mobility is compromised, reducing the range of both Plantar and Dorsi flexion, this can greatly affect your movement pattern through the full range of your squat. With a lack of flexibility there will be a tendency for your heels to rise off the floor at higher degrees of knee flexion.
This will lead to compensatory joint movements at the ankle, knee, hips and spine, which will inevitably lead to injury under load. Tightness and weakness in the ankle joint has been shown to be a contributing factor of dynamic knee valgus. Knee valgus will increase stress on the ACL and lead to injury in dynamic movements (6).
So why is hip flexibility and mobility so important when deep squatting?
Hip flexibility in the range of 95˚ of flexion is required in deep squatting (6). Lack of this flexion in a deep squat will cause an undesirable forward lean and increase the torque through the spine and vertebral shear (7). So that said lets now look at the spine and the implications of deep squatting. Many coaches and athletes will not back squat, let alone deep squat, through fear of suffering a back injury.
It is true that squatting will produce compressive forces on the lumbar vertebrae which increase with depth, it is however thought that an athlete’s spine adapts to mechanical stress by an increase in bone modeling which will increase compressive tolerance (7). During a back squat it is necessary to maintain a neutral spine, and avoiding excessive flexion and extension is a must. Lumbar forces will increase with a forward lean (9), so it’s essential to have adequate hip mobility to ensure a rigid torso and adequate upright posture.
A technique to help alleviate some lumber load would be to hold your breath during the squat movement. Dr Stuart McGill’s research found that this will increase intra-abdominal pressure which will stiffen your trunk, increasing spinal stabilization contributing to greater spinal stabilization during dynamic lifts (11). I would recommend that taller athletes adopt a slightly wider stance when deep squatting, this will help eliminate excessive forward lumbar lean and help minimize knee shear (3), while also increasing gluteus maximus activity (8). (check back to Do Training for ways to improve your hip and ankle mobility, and improving your back squat)
In conclusion, there is scant evidence to show that deep squats are contraindicated in those with healthy knee function. Squatting deep will improve your hip and ankle mobility and flexibility. It will ensure that you are getting maximum muscle activation from your quads and will get your glutes kicking in. This will lead to increased glute strength that will help to stabilize your knee and pelvis during dynamic activity within your chosen sport.
Over time your body will adapt to the depth of your squat, increasing the tensile strength of your ligaments, tendons, erector spinae, and other connecting musculature. Squatting deep will enable you to work through your full range of motion and build strength through this range. A study that is currently in press for the journal of strength and conditioning showed that “deep front and back squats guarantee performance-enhancing transfer effects of dynamic maximal strength to dynamic speed-strength capacity of hip and knee extensors compared to quarter squats.”(12) Providing even more evidence that deep squatting is very beneficial to you and your athletes.
All of the above will support you and your athletes’ in becoming more resilient to injuries, developing healthier knees, and staying out of the physio room and on the field/court of play.
So if you must back squat then make sure that you can and do….DEEP SQUAT.
Be sure to check out www.dotraining.uk regularly for training tips and advice from the professionals.
1 – Buchanan C, Marsh R. (2002). “Effects of exercise on the biomechanical, biochemical and structural properties of tendons. Comparative Biochemistry and Physiology. Part A”. Molecular and Integrative Physiology. 133 (4): 1101-7.
2 – Caterisano A, Moss R, Pellinger T, Woodruff K, Lewis V, Booth W, Khadra T. (2002). “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): 428-32.
3 – Escamilla R, Fleisig G, Lowrt T, Barrentine S, Andrews J. (2001) “A three-dimensional biomechanical analysis of the squat during varying stance widths.” Med Sci Sports Exercise. 30:556-569.
4 – Ferretti A. (1986) “Epidemiology of jumper’s knee”. J Sports Med. 3:289-95.
5 – Li G, Zayontz S, DeFrate L, Most E, Suggs J, Rubash H. (2004). “Kinematics of the knee at high flexion angles: an in vitro investigation.” J Orthopaedic Research. 27(6): 699-706.
6 – Markolf K, Gorek J, Kabo J, Shapiro M. (1990) “Direct measurement of resultant forces in the anterior cruciate ligament: An in vitro study performed with a new experimental technique”. J Bone Joint Surgery. 72: 557-567.
7 – McGill S, Norman R, Sharatt M. (1990) “The effect of an abdominal belt on thrunk muscle activity and intra-abdominal pressure during squat lifts”. J Ergonomics. 33:147-160.
8 – McGraw s, Melrose D. (1999) “Stance width and bar load effects on leg muscle activity during the parallel squat”. Med Sci Sports Exericse. 31:428-436.
9 – Race A, Amis A. (1994) “The mechanical properties of the two bundles of the human posterior cruciate ligament.” J Biomechanics. 27:13-24.
10 – Sale G, Powers C. (2001) “Patellofemoral joint kinetics during squatting in collegiate women athletes”. Clinical Biomechanics. 16:424-430
11 – Schoenfeld B. (2010) “Squatting kinematics and kinetics and their application to exercise performance”. J Strengh and Conditioning Research. 24 (12): 3497-3506
12 – Hartmann H, Wirth K et al. (2012) “Influence of squatting depth on jumping performance”. J Strength and Conditioning Research. 2012 Feb 15 (Epub ahead of print).