The Spine as a Muscular Gear-How to Bend Properly

Hundreds of thousands of pages of text have probably been written about how to bend properly, and thousands of films have been made. However, the topic is still controversial due to the lack of progress in preventing and treating spinal diseases. Dr. Stuart McGill recommends avoiding flexing the torso and replacing this movement with a “hip hinge” flexion where the back appears to be in a standing position. He is one of the most famous and staunch supporters of this technique. He shows what he thinks bending the torso should look like in a video recorded by Aron Lipsey:

https://www.youtube.com/watch?v=h3n8z1wy_SQ

In the interview for Boston Sports Medicine and Performance Group, LLC he suggests that frequent bending of the body, in his opinion, leads to injuries in BB players. He is not interested in possible other causes, such as: muscle contractures in these players or previously acquired damage to the spinal discs, invisible developmental defects and other abnormalities. Although other athletes sometimes bend very intensely, 10-20 years, and their spines do not get injured. On the contrary, during this time their bodies develop impressively. S. McGill sees only one cause: repeated bending of the torso, which, according to his research, has a limited number of cycles. The recipe is to be the “hip hinge” technique mentioned above.

The scientist calls this trunk flexion or neutral spine lifting. I caution anyone who tries to implement these recommendations indiscriminately. If you transform your vertical body column, where the spine is  neutral, into a nearly horizontal cantilever beam, you are changing to a very unfavorable structural arrangement where there are no neutral layers. The authors’ enthusiasm is rather based on their own beliefs and selectively applied laboratory experiments. In my opinion, this is a completely inadequate argument. It is not supported by a thorough analysis of the movement mechanics for these positions. Mechanics is an exact science, so the thesis requires analytical confirmation. In my opinion, the study carried out on fragments of dissected tissues from a pig carcass, which became the basis for drawing many controversial conclusions by Stuart McGill’s team, is not such a confirmation (1). Unfortunately, these conclusions have been accepted by the majority of specialists around the world as binding. Therefore, in today’s entry, I will continue my statement, mainly in reference to my blog entry regarding the spine’s role as a mechanical muscle transmission titled Is Stuart McGill’s Method For Human Body Mechanics Correct?

Classic Torso Bending Positions – How to Bend Properly

Figures 1, 3 and 5 show the classic forward, lateral, and backward flexion positions. All of these are characterized by the smooth geometry of the 3D variable axis of the spine and the shape of the torso reflecting its course. These poses perfectly show how to bend properly. When bending the torso, the body uses the force of gravity to a large extent when lowering the torso. Under gravity’s influence, the muscles on the circumference of the torso are stretched or shortened, depending on their particular flexion position. The tension zone is always on the convex side of the trunk, and the compression zone is on the concave side, as in any column or bar subject to bending, as seen in Figures 1, 3 and 5. The difference is that this condition is deliberately induced and controlled by the gears and nervous system in the human body. It is, therefore, not subject to the classical rules used in the science of the strength of materials. When bending in the standing position, the torso each time assumes the shape of the arched pylon structure, as seen in Figure 8, from which the natural force transmits through the pelvis and lower limbs to the ground. A properly shaped arch structure is characterized by the lack of bending and shearing forces.

Bending of the Body and Related Ranges of Tension

Muscles have nothing to do with the static bending of the beam, as it is commonly presented in modern mechanics of the human body. It is an automated transformation of the body structure in such a way that it adopts an optimally adapted shape to the activity performed. With proper muscle structure and balanced strength, the nervous system regulates its ranges in such a way that the arched structures formed by the torso have zero bending moments. There are also no shear forces. This situation is illustrated by diagrams in Figures 1, 3 and 5, in which the zones where the muscular system is subject to stretching, green dots, and compression, blue dots, are marked. Between them runs a neutral layer that coincides with the bending of the variable axis of the 3D spine—white dashed line. Figures 2, 4, and 6 show cross-sections through individual gear segments at a-a, b-b, and c-c, respectively, for the positions shown. They illustrate how the muscle levers work for these positions.

Forward Bend – How to Bend Properly  (Figures 1 and 2): The stretching area is in the back of the torso, and the compression area is in the front. The neutral zone coincides with the 3D axis of the spine. Figure 4 shows it marked by the A-B axis, which separates the tensile fibers marked in green and the compressed fibers marked in blue.

Compression and stretching zones of the trunk muscles - Forward bend - How to bend properly
Figure 1. How to bend properly – Compression and stretching zones of the torso muscles when bending forward
Single section of the trunk muscles - transverse section of the lumbo-abdominal segment in the forward bending position - How to bend properly
Figure 2. An example section of the mechanical transmission of the torso muscles (spine). Activating muscle compression and extension fibers around the periphery of the torso muscles spring thanks to apparent two-arm muscle levers during a forward bend – How to bend properly

Side bend – How to Bend Properly (Figures 3 and 4): The muscle stretching area is on the torso’s left side, and the compression area is on the right. The neutral zone coincides with the variable 3D spine axis. Figure 5 shows it marked by the X-Y axis, separating the green tensile fibers from the blue compressed fibers.

Compression and stretching zones of the trunk muscles - Bend to the side - How to bend properly
Figure 3. How to bend properly – Compression and stretching zones of the torso muscles when bending to the side
Single section of the trunk muscle transmission - transverse section of the lumbar-abdominal segment in a side bend position - How to bend properly
Figure 4. An example section of the mechanical transmission of the torso muscles (spine). Activation of compressed and stretched muscle fibers around the circumference of the torso muscle spring thanks to apparent two-arm muscle levers during a side bend – How to bend properly

Back Bend – How to Bend Properly (Figures 5 and 6):  The stretching area is in the front of the torso, and the compression area is in the back. The neutral zone coincides with the variable 3D spine axis. In figure 6, it is marked by the A-B axis separating the green fibers in tension from the blue ones in compression.

Compression and stretching zones of the trunk muscles - Bending backwards - How to bend properly
Figure 5. How to bend properly – Compression and stretching zones of the torso muscles when bending back
An example section of the mechanical transmission of the torso muscles (spine). Activation of compressed and extended muscle fibers around the periphery of the torso muscle spring thanks to apparent two-arm muscle levers during a backbend- How to bend properly
Figure 6. An example section of the mechanical transmission of the torso muscles (spine). Activation of compressed and extended muscle fibers around the periphery of the torso muscle spring thanks to apparent two-arm muscle levers during a backbend- How to bend properly

Figure 1–6 Descriptions

1: Variable spine 3D axis – Neutral

2: Intervertebral disc — schematically

3: Spinal vertebra

4: The group of muscles around the circumference of the trunk

5: Abdominal soft tissues

6: Part of the muscle lever arm in the compression zone

7: Part of the muscle lever arm in the stretching zone

8: Single muscle fibers in the compressed zone

9: Single muscle fibers in the stretch zone

C:  Outer contour of the compression zone

S:  Outer contour of the tension zone

X: Y-Axis and A–B axis — inert layer

X: Linea mediana anterior

Y:  Line median posterior

The spine, as a muscular gear, is located during the bending of the torso in its neutral zone, separating the compressed zone of the torso muscles from the stretched one. The condition for such functioning of the spine is the correct body structure in accordance with the Gravitational Postural Pattern (2) and the use of correct movement patterns.

Lifting Objects – How to Bend Properly

A similar mechanism works when lifting weights from the ground. Ed Coan shows how to bend properly to lift weights (Figure 7). He had an impeccable physique and so much muscular strength that he could deadlift a barbell four times his body weight using an intuitive technique.

In the first position, the starting position, the competitor has the depth of the squat adjusted to the height at which the barbell grip is located. In the second position, it is in the middle of the lift. In both positions, the competitor has a stretched zone of the back muscles, a green line, and a compressed one on the front side of the torso, a blue line. During lifting, the variable 3D spine axis separates the compressed zone of the torso muscles from the stretched one and always remains in the neutral layer.

The spine is not designed to lift weight. The muscles of the trunk do this work.

Ed Coan Deadlift. Adjusting muscle tension to the weight being lifted by changing the shape of the torso arc pylon while lifting
Figure 7. Ed Coan Deadlift. Adjusting muscle tension to the weight being lifted by changing the shape of the torso arch pylon while lifting – How to bend properly
Scheme of the arch pylon structure. Structural system free from bending and shear forces
Figure 6. Scheme of the arch pylon structure. Structural system free from bending and shear forces
Coordination of body levers when lifting objects from the ground - Correct use of "intelligent" trunk lever
Figure 9. Coordinating body levers when lifting objects from the ground – Correct use of “smart” trunk lever – How to bend properly

Figure 7–9 Descriptions

1: Variable spine 3D axis

C: Outer contour of the muscle compression zone

S: Outer contour of the muscle stretching zone

A:  Body support point —the center of the plantar fascia

R:  Ground reaction force

CW: Counterweight range

Lifting Efficiency with Arch Body Design

Thanks to the mechanical, i.e., gravitational lowering of the body in the correct body position, the competitor prepares the muscles to lift the weight. The back muscles undergo this strong, springy stretch. At the same time, the entire front wall of the muscles of the torso undergoes extreme tension—squeezing. It bears the main weight of the body. The abdominal muscles gain the greatest tension in the initial phase of lifting, taking over the entire weight of the barbell and the upper torso, transferring it to the pelvis, and then through the legs to the ground. At this time, the back muscles stabilize this lifting with “their stretch” and then contract, causing the trunk to be successively straightened—lifting. The pattern of action of the muscle levers in lifting with a bent back is the same as in Figure 2.

Peripheral muscles along the entire height of the torso behave like a special spring bent along its axis, accumulating a mixture of kinetic and mitochondrial energy when lowering the torso. This energy charge is used to lift the weight during effective extension.

At the same time, the bent legs are successively straightened. The rear part of the torso, which is significantly extended beyond the fulcrum “A” (lift axis), constitutes a counterweight (section “CW”) that balances the weight of the barbell. At the time of lifting, it is usually a dynamic counterweight for a fraction of a second, facilitating lifting. In each lifting position, the spine is in the neutral layer of the trunk. It is the most effective and safe lifting mechanism. An exercise program based on the movement patterns described above results in balanced and safe muscle development without exposing the spine to deformation and destruction.

The muscular mechanism uses mitochondrial energy and gravitational energy acting on the plastic-elastic structure of the muscles by compressing it with the force of gravity of the body and the lifted weight, as well as the reaction force coming from the solid ground. It can be called a hybrid muscle engine that drives the whole body. (3)

Utility Lifting: The deadlift is just a special kind of lifting. People lift weights of various, not always comfortable shapes and often without special handles, placed on the ground. These lightweight ones can be easily lifted without much effort. How to correctly bend when lifting objects from the ground is shown by the model in Figure 9. Other large and heavy items require strength and concentration. However, bending to pick up weight from the ground should always follow a pattern similar to the pattern shown in this illustration.

How Not to Bend – Hip Hinge Torso Bending

Why is hip hinge bending not correct? Mainly because the torso in this technique is changed from a vertical structure, in which the spine is in a neutral position, to a cantilever beam, which is subjected to a very large bending moment, especially in the case of weightlifting. In addition to the fact that this is a particularly unreliable construction, it is disconcerting that the spine with this technique is not only not properly secured by muscle tension but is directly subjected to bending and shearing forces.The body flexion recommended by body mechanics theorists is shown by the model in Figure 10. She is the same extremely fit and athletic competitor performing the excellent backbend in Figure 3. Despite her impeccable physique, her hip-hinge flexion pose looks pretentious. It excessively bulges in the front part of the torso, deprived of proper muscle tone. The shape of the torso has been moved here from a vertical to a horizontal position, which does not automatically transfer the position of neutral body mechanics. Any engineer will point out that there is a fallacy in this reasoning.

Bend forward using the "hip hinge" technique. Abnormal movement pattern.
Figure 10. Bend forward using the “hip hinge” technique. Abnormal movement pattern.
Diagram of the cantilever beam structure. The most unfavorable beam structure - high bending and shear forces
Figure 11. Diagram of the cantilever beam structure. The most unfavorable beam structure – high bending and shear forces
Deadlift using the "hip hinge" technique. Very high bending and shearing forces, especially in the lumbar section.
Figure 12. Deadlift using the “hip hinge” technique. Very high bending and shearing forces, especially in the lumbar section.
Scheme of activating muscle tensions in the mechanical transmission layer of the torso in the lumbar-abdominal section during forward bending (figure 10). – cross-section d-d. Dominant muscular compression of the back muscles - imbalance of the muscles of the front and back of the torso
Figure 13. Scheme of activating muscle tensions in the mechanical transmission layer of the torso in the lumbar-abdominal section during forward bending (figure 10). – cross-section d-d. Dominant muscular compression of the back muscles – imbalance of the muscles of the front and back of the torso
Lifting with the torso transformed into a "diagonal cantilever beam" position (straight back). An unsafe lifting technique used as an alternative to the "neutral torso shape" (Figure 12).
Figure 14. Lifting with the torso transformed into a “diagonal cantilever beam” position (straight back). An unsafe lifting technique used as an alternative to the “neutral torso shape” (Figure 12).
Scheme of activating muscle tensions in the mechanical transmission layer of the torso in the lumbar-abdominal section during deadlifts (Figure12). – cross-section e-e. Dominant muscular compression of the back muscles - a gross imbalance of the muscles of the front and rear of the torso.
Figure 15. Scheme of activating muscle tensions in the mechanical transmission layer of the torso in the lumbar-abdominal section during deadlifts (Figure12). – cross-section e-e. Dominant muscular compression of the back muscles – a gross imbalance of the muscles of the front and rear of the torso.

Figure 10–13 and 15 (Descriptions)

1: Variable spine 3D axis

2: Intervertebral disc — schematically

3: Spinal vertebra

4: The group of muscles around the circumference of the trunk

5: Abdominal soft tissues

6: Part of the muscle lever arm in the compression zone

7: Part of the muscle lever arm in the neutral zone

8: Single muscle fibers in the compressed zone

9: Single muscle fibers in the neutral zone

C: Outer contour of the muscle compression zone

N:  Outer contour of the neutral zone of the muscles

X-Y axis and A-B axis — inert layer

X – Linea mediana anterior

Y – Line median posterior

The model, bending her torso forward, changes the static scheme of the body to the type of cantilever beam shown in Figure 11. However, the “living beam” works differently. It is necessary to tense the back muscles to maintain the leaning position and to counteract the stretching of the upper section of this “beam”. Its lower part remains slightly tense. The body tries to protect the unprotected spine, which has lost its position in the neutral layer due to harmful compression of the paraspinal muscles along its entire length, shown by the blue “C” line along the back (Figure10). Mutual muscle tension in the front and back of the trunk was completely disturbed. This condition is also shown in the cross-section of the trunk d-d (Figure 13). Lifting the bar using the hip hinge technique has much more serious consequences (Figure 12 I 14). While in the visual assessment, the body’s position did not undergo any special changes in relation to the unloaded position, the actual tension of the posterior myofascial bands increased dramatically. The upper part of the body, including the paraspinal muscles, undergoes very high compression, which has a destructive effect on the intervertebral discs. This zone has a double blue “C” line signaling strong compression (Figure 12 and 15). The spine is subjected to uncontrolled compression and is additionally subjected to severe bending and shear forces. A slightly better lifting position was adopted by the athlete with an oblique torso (Figure 14). However, it is still a harmful cantilevered torso design.

Lifting efficiency thanks to the “hip hinge” method

Can you develop muscle by lifting weights using the “hip hinge” method? Of course you can. This is how the vast majority of people in gyms train nowadays. This method of training even affects the faster development of the back muscles at the expense of other parts (disturbed balanced development). Athletes balance this disorder with an increased amount of isolated exercises: arms, chest, abdomen and other muscles. Of course, the most difficult thing to develop with them is the abdominal muscles. However, even such a developed muscular system seems impressive to most of us. The biggest disadvantage of such development is the gradual destruction of the mechanical structure of the muscle transmission (spine). This is caused by the powerful compression of the paraspinal muscles that occurs when lifting using the “hip hinge” technique. The nervous system activates it to protect the spine from critical damage. Very high shear forces on the lumbar section without skeletal reinforcement are also destructive. Athletic people with strong muscles and a severely damaged spine often come to orthopedists. S. McGill writes that these cases prove that strong muscles created by resistance exercise methods do not affect the protection of the spine. He believes that exercises in which the torso is bent cause a hernia in the spine. That’s not true. Such damage is caused by bending the trunk using the “hip hinge” technique. Bodybuilders and senior athletes who have missed out on this “modern method” continue to exercise with good results even into their 70s and 80s.

To ensure proper functioning of the spine, proper body posture must be maintained, consistent with the Gravitational Posture Pattern. You should abandon the “hip hinge” technique during exercise and other activities. This technique should be replaced by the formation of an arched trunk pylon (Figs. 1, 3 and 5 and 7 and 9). You should also avoid prolonged sitting without compensatory exercises.

  1. SM McGill and JP Callaghan in 2001 entitled: Intervertebral disc herniation: studies on a porcine model exposed to highly repetitive flexion/extension motion with compressive force
  2. Marian Jodlowski, Chapter 7 – Human Gravitational Postural Pattern, Fix Your Back Like ana Architect, Amazon 2022
  3. Marian Jodlowski, Chapter 3 – Man as a Biomachine, Fix Your Back Like ana Architect, Amazon 2022

Figures No. 7 were used as polemical quotations (Fair Use).  

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