The Gift of Injury by Stuart McGill and Brian Carroll, (05) The Injury Explained, Notes

Post date: Apr 19, 2019 2:26:15 PM

The Gift of Injury by Stuart McGill and Brian Carroll

Chapter 5: The Injury Explained - Powerlifting and Strongman events reach a tipping point where peak performance is produced and records are broken. But cross that point and the supporting tissue will crush under compression, or tear under excess strain. These crushes and tears range from the most debilitating to less noticeable microfractures. Building the spine to bear more load actually requires some microfracturing by training with heavy weights as part of the adaptation process. Overloading during training will either cause an adaptation that increases spine strength, or, when pushed too far beyond the tipping point, microfracture accumulation that evolves to macro damage and pain. Knowing when to stop adding weight and how to recognize how much is too much is an insight that can be trained.

• • Generic Injury Processes and Patterns: The injury-causing variables of greatest concern for the strength athlete are compressive stresses and spine bending loads. The majority of the compression load on the low back actually comes from the back and torso muscles as they contract to support load. A function of leverage: the load on the bar is in front of the lumbar spine. The muscles in the back must contract to counter this forward bending movement. Because they are closer to the spine than the load force vector, they must create greater forces than the load on the bar. These muscle forces, together with the load on the bar, and the upper body mass are imposed on the spine. The loads carried through the spine are often ten times the actual load on the bar.

    • The majority of spine compressive load comes from the back and torso muscles contracting to support the base load (largely influenced by lifting form.) These loads will produce damage when they exceed the tolerance, or load bearing strength, of the spine.

    • Excessive compressive load will initiate microfracturing of the disc end-plate and underlying bone.

    • The inside of each vertebrae has many struts of bone which support loads and allow the transmission of weight throughout the structure. It is essential that the struts run vertical and horizontal to prevent the vertebrae from breaking or buckling. These struts determine whether or not the vertebrae can successfully bear heavy loads. Strength training that involves progressive overload, thickens these struts, but this process takes years. Being too aggressive with load causes the athlete to cross the tipping point. Being patient and properly structuring loading cycles that include sufficient rest periods, stimulates bone growth and encourages adaptation.

    • When the vertebrae are taken beyond the tipping point and microfracturing occurs at the end plate, the cartilage no longer serves it supportive purpose as scaffolding. With adequate rest and properly designed periodic training cycles, the end plate will slowly gristle and callous, giving the spine more ability to bear load than previously possible. If, however, a proper rest period is not taken and weighted training is applied too soon, the increased pressure on the disc annulus will cause the collagen fibers to rip away and the delamination process is then accelerated, causing painful injury.

    • The tipping point is different between individuals and is influenced by differences in anatomy, the extent of the damage, rest time taken to callous, genetics and luck.

  • Spine Bending Under Larger Training Loads: Tolerance level to bend-related injuries is determined by hip anatomy, leg to torso length levers, spine thickness, spine shape, genetics, rates of repair and reaction to training progressions. Spine bending under load may lead to enhanced athleticism in some, but it is usually temporary, eventually ruining backs. Be aware of the stresses and the adaptation process. Be patient and place trust in those who best understand biological processes and injury resilience.

    • The outer rings of the spinal discs are strands of collagen held together with and adhesive ‘ground’ substance. Adaptation to motion (spine bending and more mobility) involves a softening of the collagen ground substance. This softening equates to a weakening, and is therefore the enemy of the strength.

    • In contrast, this softening is what makes gymnastics possible. The physical demands of the powerlifter are quite a different set of requirements than that of a gymnast. Therefore, they must train differently.

    • Under compressive load, the nucleus gel in the middle of the disc becomes pressurized. When the mobile spine (adapted from mobility training) has been stretched and bent, the collagen fibers will eventually delaminate under the hydraulic pressure built up in the nucleus, or inner disc. In contrast, a disc subjected to high compressive loads that do not bend (i.e. good form in powerlifting) will stiffen and become resilient to delamination. Strength athletes should avoid yoga (the spine bending poses) and spine stretching. The buttwink, when squatting under load, will eventually cause problems. Stay tight and ‘locked in’ and let the hips power the rigid torso.

  • Disc Bulges - There is usually a combination of factors that set up the collagen delamination, and eventual disc bulge. For example, damage to the bone end-plate with excessive deadlifts on an untrained spine causes delamination to occur as the collagen fibers rip away from the end plate. Then, more spine bending of the spine under compressive loads allows the collagen fibers to delaminate further. Eventually the nucleus material extrudes, firing off stabbing pain, as inflammation irritates nerves, compressing the roots directly. Disc bulges are caused by poor training. The way to avoid this is to allow the discs to stiffen by reducing spine bending throughout the day and training with minimal spine motion.

  • The Bigger Picture - We cause a lot of our own pain and injury through repeated poor posture and movement patterns, all the while denying the body the healing time it needs. We must earn a capacity to train pain free.