Is Stuart McGill method for human body mechanics correct?
The Stuart McGill method has spread all over the world. He has become a great authority on treating back conditions and injuries for athletes and other patients. In my opinion, his suggestive way of conveying information, persuading opponents, and the authority of the university he represents played a significant role here. Are his indications correct? Unfortunately, McGill’s general body mechanics strategy is incorrect. However, some of his recommendations for spinal injury rehabilitation may be beneficial in some cases. Its activity can be divided into two main fields:
A. Procedures related to the rehabilitation of the damaged spine
B. Procedures related to the final performance of the athletic spine
A. Stuart McGill Method — Procedure Related to the Rehabilitation of the Damaged Spine
The tissue-sparing strategy for rehabilitating damaged spinal and paraspinal tissues is the right one. Starting exercise or stretching the inflamed areas too early may further damage the discs and possibly rupture the annulus fibrosus. Each increase in damage is associated with an extended rehabilitation time of this section, which sometimes lasts many months, and even much longer. Non-invasive recovery is associated with long-term self-healing, which can destroy any reckless tissue strain. In particular, any kind of mechanical means of stretching should be avoided. Unfortunately, manual therapists who can improve the first stage of treatment are rare, while allegedly highly qualified medical teams offering “modern” and, in fact, very dangerous stretching systems are not uncommon.
The Stuart McGill method of recommending the use of the hip hinge during various activities in acute pain may temporarily help protect the affected tissues, provided that there is no excessive flexion that stretches the fibrous rings in the lumbar spine (tension dilating the fibrous rings directly at the sacrum). Such protection can be helpful for people with weak abdominal muscles or a very round stomach.
For people with stronger abdominal muscles, the best protection method is to stabilize the spine by tightening them, partially pulling them into the abdominal cavity, and tightening the buttocks. This method leads to a pelvic tuck and a slight curvature of the back that eliminates lordosis. Bend over to lift only light objects should be replaced with a moderately deep squat. You can also kneel. Ruthless sparing of tissues around the spine in the case of sciatica should last even many months. Any activity that causes neurological pain should be avoided.
B. The Stuart McGill Method — Harmful Recommendations Related to the Ultimate Performance of the Athletic Spine
The recommendations of McGill and his team in rebuilding the body regarding movement patterns based on the hip hinge for people after rehabilitation or competitive athletes are incorrect and even harmful. The main irregularities include his claim that the spine
- has bending intolerance,
- is a kind of flexible beam or mast that bears the weight of the torso together with the payload, and
- to bend the torso, use the hip hinge while stiffening the back, giving it the shape of natural curves, such as in a standing position.
The Stuart McGill Method challenges the workings of the natural mechanics of the human body. It introduces an artificially created movement with the back positioned as in a standing position for all possible positions for which such adjustment is possible. Here is an example YouTube video by Aron Lipsey of McGill’s recommended squat bends:
I watch with great concern the laborious attempts of these men to cope with the squat. In this situation, I recommend the squat to everyone, which people have been doing for thousands of years, not long after birth (Figure 1-3) until old age. Arnold Schwarzenegger also used this squat for lifting the barbell in the rear position (Figure 4). This squat is a natural position that we owe to evolution. It is unnecessary to practice strange squats, but muscles that should be flexible, balanced, and strong.
Although man is a complicated bio-machine functioning on the basis of his own energy, a significant part of his movements consists of static systems, which he takes as the initial, final position, as well as intermediate positions. Their correct application can therefore be relatively easily assessed. A comparison of the static systems proposed by the Stuart McGill Method is presented in the entry Rounded Back Deadlift Vs. With Hip Hinge (Figures 1-5 and 7-14). They show that the position with a neutral spinal shape—the same as the standing position—when bending over and lifting weights is the most dangerous for the spine. However, in the position with a rounded back, stabilized with posterior myofascial tapes, there are only natural compression forces that do not generate bending and shearing forces. Do not confuse bending forces with the formation of the arch structure of the body by the muscular system. Below are the next arguments why the Stuart McGill Method uses invalid arguments.
Below Is Why Nature Created the Body for Versatile Bending
The spine bends along its entire length, but two of its sections have a special reason for this.
Musculoskeletal Structure: Shows that nature created man in such a way that he bends his body, although body mechanics specialists do not always consider it. Figure 7 shows a horizontal section of the neck. About 90% of the area of this cross-section in section “D” (Figures 5 and 6) is made up of soft tissues, including the muscles of the neck and only 10% of the mobile skeleton of the spine. This skeleton is not a column, despite the nomenclature adopted in anatomy. It is an ordered set of skeletal elements loose as bricks. It is connected by relatively soft tissues such as intervertebral discs, ligaments, and fibrous rings, which, if necessary, provide it with extraordinary mobility to position the head by bending up, down to the sides, twisting, twisting with bending, and the like.
The structure of the lumbar spine is very similar to the cervical section. This section is marked “B” in Figures 8 and 9. He also has no skeleton reinforcement. There is only a movable section of the spine, which is about 10% of its horizontal cross-section, which itself requires stiffening with muscles if necessary. So, it’s hard to say that it strengthens this episode. The muscles of the back and the circumferentially located other muscles of the torso account for about 50% of the area of this cross-section. The remaining 40% are internal soft tissues—viscera. Thanks to the intensive work of properly built abdominal muscles, which participate in bending the torso, these viscera are subject to constant massage, which supports their blood supply.
The joints of the spine also prove that nature created man in such a way that he could bend his body. The vertebrae of the spine have symmetrically arranged articular processes in their posterior part. Their lower and upper surfaces form pairs of joints that provide the bending and twisting movements associated with each of the spinal discs. The exceptions are the two upper cervical joints, which have only a rotational function.
How does the spine bend?
Below are links to three short videos showing the correct ranges of spine bending for basic positions. They were prepared as virtual spinal models for forward, backward, and sideways bending by Dr. Zbigniew Sawicki, a Polish specialist in the field of rehabilitation and physiotherapy. The link to each of the videos is preceded by a photo of a competitor whose body bend corresponds to the range of bending of the spine presented in the video.
The Range of Bending the Spine Forward
Link to the video: https://www.youtube.com/watch?v=Dk9ZN8PsxqU
Backward Bending of the Spine
Link to the video: https://www.youtube.com/watch?v=NHMLDo293wM
Lateral Flexion of the Spine
Link to the video: https://www.youtube.com/watch?v=hW5lhXLYxB4
The flexion ranges shown in the videos are only a simplified diagram of such movements and may vary from person to person depending on their individual anatomy. The actual movements of the spine are much more complicated due to the presence of intermediate forms of bending, twisting, bending with twisting, or similar things.
As you can see in the presented videos, the spine bends easily together with the whole body of the body. If its vertebrae and discs have not been deformed before and are set correctly on the 3D axis of the spine [FYBLA*], the muscle tension automatically stabilizes their correct position in every body position and lifted weight, preventing their lateral displacement. The trunk then forms an arch structure where only normal—compressive—stresses occur. This mechanism not only maintains the alignment of all vertebrae but also prevents excessive loading of individual discs along the 3D axis. The correct spacing of the vertebrae is given to the muscles attached to them, which are automatically tensed in proportion to the force acting on them.
How Do Athletes Use Bent Backs?
Even though Stuart McGill’s Method says that bending the back is harmful and that a person should use a braced spine as shaped as in a standing position, people are forced to bend it every day. It is hard to imagine performing basic activities without it, not to mention practicing various sports. Figures 14-17 show the players’ position in which the strong contraction of their abdominal muscles is closely related to the arching of the back.
Although the Stuart McGill Method says that bending the back is harmful and that a person should use a braced spine as shaped as in a standing position, people are forced to bend it every day.
These positions determine the explosion of strength and ensure the proper dynamics of movements. In the run of such animals as lions, leopards, gazelles, or common hares, the back also undergoes dynamic bending and straightening. They probably will not stop bending their spines, although, from the supporters’ point of view of using the hip hinge, they are in a lost position.
Incorrect Knowledge of the Mechanics of the Human Body
It’s not just Stuart McGill’s Method that is flawed. The state of knowledge about the mechanics of the human body, particularly the mechanics of the spine, is low. New research conducted in the 21st century has caused its regression in many fields instead of developing this knowledge.
Incorrect knowledge is passed on massively and willingly. Speakers often hold overly stiffened plastic models of the spine in their hands and suggest to patients that a rigid spine bears the weight of the entire torso and lifts great weights. Perhaps such rigid spine models are produced for the convenience of speakers. However, I believe that in this situation, they should also have a complementary model with loosely arranged elements of the skeleton strung on a string. In that way, the recipients can get acquainted with how the skeletal structure of this section is actually dismembered. The physical condition of the stiffened spine models used for the presentation resembles the stiffness of the spinal skeleton a little dissected from the muscular system. One that has left flexible and semi-flexible tissues, such as spinal discs, fibrous rings, and ligaments that hold it together. All of these tissues become permanently stiffened as a result of death. But I think that even in this condition, the column is not as stiff as the production models without these tissues. It should be added that a living organism almost never has a physical state of the spine, such as in the models used in these presentations. In fact, it is extremely mobile, thanks to the muscles’ energy and the nervous system’s dispositions. It bends very easily because it is temporarily devoid of stiffness and undergoes variable stiffening ranges on its individual sections. When transferring large forces, it undergoes powerful stiffening along its entire length thanks to muscle tension both in the back flexion positions and when they are straight.
Without living muscles, flexed mainly by gravitational muscle tone, and elastic or semi-elastic tissues, the skeleton is nothing more than a set of loosely arranged “building blocks”. I noticed that these models are mainly used to convince listeners that the spinal column, and the muscles attached to it, are responsible for lifting weights and taking over the forces loading the torso. But the speakers explain very enigmatically how it is done. Dr. McGill put it this way:
The spine is a stack of vertebrae that is asked to bear loads, yet it is flexible. A design engineer will tell you that you can’t design a structure to be good at both. A steel beam that is straight and stood on its end is stiff, and can bear loads that try to compress, shear and twist it. So the beam can bear load but it can’t move. A flexible rod that allows movement will bend and buckle under load, but absorbs shock. Our spines do it all ‐ they bend and allow the lungs to fill with air, and even allow us to dance. 
And indeed, it is almost as McGill wrote. The spine is not a beam. Its various forms of stabilization in space are provided by variable myofascial tension, on which its operation depends. Nevertheless, the science of body mechanics maintains that the spine bears loads and presents static diagrams showing the distribution of forces in this section as for a simple beam that absorbs the forces acting on it. Their authors rather do not have dilemmas such as those presented in the above quote. Stuart McGill’s Method is also based on these stereotypes, although the author probably recognizes its inconsistency.
I believe that the chaotic use of knowledge, in this case, is due to the fact that modern medicine omits many important conditions without which it is impossible to properly interpret and understand the mechanics of the human body, as well as to remove the contradictions, as mentioned earlier. The most important of them are as follows:
- Failure to recognize the mechanisms, thanks to which the human body assumes a vertical position and a person can walk and run, obtaining kinetic energy thanks to gravity that supports the functioning of the muscular system. How this mechanism works, I described in my book FYBLA*.
- Failure to recognize the presence of micro-dilatation between the articular surfaces in the joints’ anatomical structure, which I believe plays a key role in adopting an upright body posture. They also enable long-term painless functioning of the joints and versatile and precise performance of various activities. The principle of operation of such joints is presented in the Static and Dynamic Stabilization of Joints chapter of my book FYBLA*.
- Lack of actual recognition of the mechanics of the trunk and the actual role of the spine in the human body, particularly its cooperation with the muscular system. In my book, I wrote that the spine is not designed to carry loads. It is a mechanical muscle gear that directs muscle tension and relaxation in individual body positions. I intended to present the mechanics of this episode in my second book. However, before writing it, I decided to prepare special blog entries devoted to this topic. Below, I present the idea of the operation of the spine as a mechanical muscular transmission. The topic will be developed in the next entries.
The spine as a Mechanical Transmission of the Trunk Muscle Forces
At the beginning, a short quote in which McGill briefly characterizes the modern mechanics of the spine in the human body:
The spine is a flexible rod which must be stiffened so that it is able to support tremendous compressive loads from the muscles pulling it downwards together with the weight of the bar. Packing provides the most stiffened and stable supporting pillar to enable the full power developed at the hips to extend, pulling the hips forward without allowing the spine to bend loosing energy. 
Critical Remarks About the Quote
- The spine is not a flexible rod. It is a free structure that, in different body positions, is temporarily subject to various forms of stabilization caused by muscle tensions resulting from the impact of gravity and the reaction of the ground to these forces.
- Muscle compressive loads do not pull the spine down. On the contrary, their muscle tone, proportional to the weight, blocks the excessive approach of the intervertebral vertebrae, fixing their position in such a way that the spinal discs are protected from excessive pressure.
- The spine does not generate any energy, so it cannot waste it—it is made in the muscles. When bending the body, the resulting kinetic energy is used from gravity by the elastic structure of the muscles, among other things.
Contrary to the method of Stuart McGill and his followers, the human torso undergoes a variety of bending. There is no danger in this. On the contrary, flexion positions are more secure than the so-called hinge flexion and isometric trunk contraction tests recommended by hinge flexion theorists. It is worth considering whether some of the isometric exercises of McGill’s Big Three will not cause hypertension in the future in exercising patients.
The spine is not responsible for lifting weights. This function is performed by the muscles around the entire circumference of the torso (Figure 20), and the spine as a gear regulates the ranges of muscle tensions along the full height of the torso, setting them depending on the adopted body position. Each of its discs, along with the vertebrae directly adjacent to it, above and below, regulate the range of bending in different directions of the trunk. The brain reads the positioning of the vertebrae, the center of gravity of the body, and the force vectors from gravity in space through the nervous system, which automatically regulates the range of muscle tension. If the muscles are not properly developed or imbalanced—muscles overstretched or contracted—the brain signals the abnormality, causing pain. The next stage is further deformation of the muscular system, then the skeletal system, and the consolidation of destructive changes.
Figures 18-20 show a diagram of the gear operation for one of the discs located at the lumbar level, with the body lateral flexed by the athlete to her right (Figure 18). A gear element assigned to a single disc regulates various ranges of forces acting on the circumference of the torso via double-sided levers. They generate alternating compressive and tensile forces in the muscle fibers—right and left sides. These levers are created automatically for various positions taken by a person by the nervous system that manages the functions of the body. A special case of a compression and extension lever with maximum opposing deflection is denoted by the letters RL, an isosceles lever. Other exemplary levers on the circumference of the torso were set randomly. Each of them has a dummy rod that passes through a fulcrum in the center of the spinal disc (axis of rotation of the lever—red dot) and connects opposing muscle fibers on the left stretched side (green dots) and the compressed right side of the body (blue dots). The X-Y axis marks the neutral zone in which no muscular force is generated over the entire height of the torso. In front, this zone is formed by the linea alba and the line of the sternum of the chest. On the back, there is a line of spinous processes. Neutral zones separate the active muscles of the right and left sides of the torso.
According to this division, due to the scale of the drawing, only a small number of exemplary muscle levers have been designated on the plan view. On the other hand, on the vertical section of one section of the spine (figure 19) between the lines running in the middle of two adjacent vertebrae, two extreme levers (upper and lower) were marked, respectively, for the simplest symmetrical distribution of forces. The actual number of such levers and the muscle fibers assigned to them should be considered uncountable. The purpose of the analysis is not to over-detail this issue but to indicate the principle of operation of the musculoskeletal system of the trunk.
Such levers are created by the nervous system separately for each position of the torso bending forward, backward, anterior-lateral, and posterolateral, as well as for torso turns.
It should be emphasized that in none of the discussed positions do the spinal discs take over the weight acting on the human body. They are only an articulated support for the levers generated at individual levels of the trunk by the nervous system, performing a neutral function. Despite this, the spinal discs, in some cases, take on certain forces that I wrote about in my book. They also bend slightly, acting as elements of the muscular transmission that manages the adoption of various body positions, including the most important one, standing. There will be more about this function of drives in the next parts of the blog.
The commonly passed knowledge that the spine transfers the loads of the torso through its discs and lifts weights through them is false. The above analysis showed that the discs do not take over the loads in the trunk transmission, which is the spine. This is because in the muscle levers, which are the components of this gear, only function as the axis of rotation, transferring the forces to the muscles around the entire torso.
In my opinion, modern knowledge about the mechanics of the human body, including the Stuart McGill Method, is burdened with so many errors that the vast majority of hundreds of thousands of publications in the form of books, articles, or instructional videos, based on it, may turn out to be incorrect in whole or in large part.
*FYBLA—FIX YOUR BACK LIKE AN ARCHITECT, Gravity Therapy of the Spine, and Motor Organs—Marian Jodłowski, Amazon edition
** For the definition of the 3D axis of the spine, see the Movement Patterns chapter of my book.
- Stuart McGill, November 30, 2014, Why Everyone needs Core Training, backfitpro/Blog/McGill Articles
- Stuart McGill, July 3, 2018, Head position and the deadlift, backfitpro/Blog/McGill Articles
*FYBLA—FIX YOUR BACK LIKE AN ARCHITECT, Gravity Therapy of the Spine, and Motor Organs—Marian Jodłowski, Amazon edition