Spine stability-abdominal brace and hollowing

Stabilizing exercise is very popular in the treatment of low back pain (LBP). The goal of this type of exercise is to optimize the activation and coordination of the muscles around the spine while minimizing the compressive load on the spinal tissue. The exact mechanism of this benefit has not been elucidated, but stabilization exercise combined with daily activity changes has been shown to be effective in the treatment of LBP.

At the heart of the spinal stability theme is how the patient activates the abdominal muscles and the progress of proper exercise for maximum benefit. A previous study by the Queensland group in Australia (Hides, Richardson, Jull, etc.) showed that the transverse abdominal muscle (TrA) was later adopted in LBP patients, presuming that the spine was unstable or unhealthy. I did. This has also led to the development of specific rehabilitation protocols, including attempts to exclusively activate and rehabilitate TrA, primarily using abdominal depression techniques. However, most of the existing evidence that supports this concept is indirect or qualitative. In fact, TrA has been shown to be separable only at very low levels of activation (maximum voluntary contraction or 1-2% of MVC).

At higher levels of activation, such as during normal activities of daily living and exercise, TrA has been shown to have a synergistic effect with the internal oblique muscle (IO). In light of this, the first study on TrA suggested that motor dysregulation is present in patients with LBP, and TrA is not always the most important factor in this relationship. In subsequent studies, LBP patients not only delayed the activation of TrA, but also delayed other trunk muscles when moving the torso quickly, suppressed knee extensor muscles, disturbed buttock firing patterns during walking, and severely. Breathe and maintain spinal stability. This indicates an overall loss of muscle coordination rather than a specific loss of one muscle.

When the TrA study was born in Australia, the University of Waterloo’s Biomechanics Lab (McGill and his PhD students-Grenier, etc.) modeled the spine and how muscles contribute to spinal movement and stability. We have developed an advanced and validated method of calculating what to do. Evolving from this task is the support of abdominal braces as the best way to activate the muscle tissue of the spine. They also developed “Big Three” exercises for spinal stability rehabilitation-curl-ups, front plank / side bridges, and cross scrolls. These exercises maximize muscle activity while minimizing spinal cord compression.

Here it is important to establish some definitions that generally apply to this study, and this rehabilitation topic.

• Spine Stability-The ability of the spine to withstand applied perturbations (known as Euler’s spinal stability). Equilibrium is not achieved if the input energy (perturbation) is greater than the potential energy of the column (stored in the intervertebral discs, ligaments, muscles, tendons).

• Abdominal depression-Attempts to isolate TrA by activating the inferior abdominal wall while gently “pulling in”.

• Abdominal Brace-Contains to activate the abdominal muscles around the spinal column to levels that increase torso stiffness.

This study, conducted at the University of Waterloo, aims to determine which muscle activation strategies (abdominal depressions or abdominal reinforcements) are more effective in stabilizing the lumbar spine. Eight healthy male subjects aged 20-33 years participated in this laboratory study. EMG data and biomechanical model simulations were used to measure spinal stability under four stress conditions performed with two stabilization strategies, brace and hollowing. The four load conditions are:

1) No load on hands (no lift)

2) One hand 10Kg (bilateral lift)

3) Only the right hand is 10Kg

4) Only the left hand weighs 10 kg. EMG records were taken from surface electrodes placed on the rectus abdominis, IO, EO, latissimus dorsi, thoracic erector spinae muscles, lumbar erector spinae muscles, and lumbar multifidus muscles.

The IO record was presumed to represent TrA activity, as it was previously established that TrA and IO are synergistic (this presumption has been previously validated). Both brace and hollowing were performed with ultrasound imaging guidance according to previous studies. Spinal kinematics was measured and modeled using a 3D imaging Isotrak system. The main outcome indicators used were spinal stability index and spinal cord compression (calculated by laboratory modeling techniques using raw data, respectively).

The appropriate results for this study are:

• Both simulation and in vivo data showed that the abdominal brace was superior to the abdominal indentation, or that lower compression improved spinal stability.

• Brace increased spinal stability by an additional 32% compared to indentation, but increased compression by only 15%.

• Selective activation of TrA has proven to be very difficult, if not impossible, in all subjects. This is also evident in the fact that all other abdominal muscles are not silenced during the abdominal depression. This suggests that the abdominal depressions appear to provide some brace.

• All simulations performed showed that TrA did not affect spinal stability.

Conclusion and practical application:

The results of this study show that abdominal braces are an excellent strategy for increasing spinal stability and reducing spinal load compared to abdominal depressions. The authors quickly realized that these results do not undermine the potential benefit of hollowing out for retraining TrA deficiency in terms of motor control, as TrA deficiency is still part of the abdominal wall. I pointed out. However, the general advice from therapists and exercise professionals to “pull in” for stability seems to be misdirected. It may also be relevant that this study showed that attempts to hollow out appear to mobilize other abdominal muscles and thus represent low levels of brace. The authors speculate that the layers of the abdominal wall may combine during muscle activation, increasing spinal stiffness. If this is true, TrA remains important as a member of the “Muscle Orchestra” rather than a single contributor.

Returning to the initial findings of delayed TrA activation in patients with low back pain, the authors of this study cleverly suggest that this finding may be “statistically significant, but not mechanically significant.” ing. From a practical point of view, abdominal braces are easy to achieve and appear to be a more effective strategy for implementation in LBP patients. The exact role of TrA-specific training needs further investigation.

It should be noted that this was a small study conducted on a small group of healthy subjects. Further research is needed to quantify these relationships in older patients with low back pain and other patient populations.