FLEXION RELAXATION RESPONSE & LOW BACK PAIN

Over time, we have discovered that the circumstances that makeup LBP are not all the same. We now know that although some people’s pain is caused by particular patho-anatomical or structural factors, others are not. We’ve discovered that sometimes, but not always, our deep-stabilizing muscles start to function differently. We’ve also that certain movement patterns might be pain-causing. We are now looking for the most effective method to ascertain why dysfunctional movement patterns develop if they are adjustable, and what we can do regarding it. The idea of adaptable movement patterns is key to this.

Our ability to move our trunks is made possible by the lumbar spine and hip joints, which are joined by the pelvis (Kim, 2013). The coordination of movement is often disrupted, resulting in stress in static positions, load across the range, and load at the end of the range on lumbar spine components.  Unfortunately, no one movement pattern can accurately describe back pain, and each person moves differently depending on their pain triggers. Sadly, there can’t be a “one size fits all” strategy.

WHAT DO YOU MEAN BY THE FLEXION RELAXATION RESPONSE (FRR)?

Up to the very end of the range, when there is a sharp decline in muscular activity, the erector spinae muscles govern flexion eccentrically. The flexion-relaxation response (FRR), as it is known, is crucial for obtaining complete range of motion (Kim et al., 2013; Zwambag & Brown, 2015).

Ideally, the lumbar spine initiates lumbar flexion during normal movement. The movement is mostly controlled by the lumbar spine during the first half of the possible range. The hips then start adding more to the possible range after this and towards the conclusion of forward bending. The entire expression of lumbar flexion depends on the FRR, which has been consistently seen in healthy participants (Neblett et al., 2014).

According to research, when the paraspinal muscles stretch, the joints and passive structures’ mechanoreceptors are activated. As a result, the paraspinal muscles become inhibited and the passive structures continue to offer stability towards the end of range (Kim et al., 2013). This in turn sets off a stress-inhibition response. According to Zwambag and Brown (2015), this is referred to as a load-sharing system among active and passive structures. Absolute flexion angle is a term used to describe the angle at which this phenomena takes place (Zwambag & Brown, 2015).

WHAT CAN YOU MEASURE FROM WHAT YOU SEE?

In the clinic, you could evaluate fingertip distance from the floor, range of motion, or how far the hands glide down the shins using a goniometer. Several research have used surface EMG to analyse muscle activity and 3D video analysis to quantify the range of motion and contribution of the hip and pelvis as well as the lumbar spine (Kim, et al. 2013). According to a meta-analysis, surface EMG and ROM analysis may boost evaluation sensitivity and specificity by 88.8% and 81.3%, respectively (Geisser et al., 2005, p. 721). This basically indicates that in order to identify the kind of pattern of movement we are attempting to cure, we must keep looking for methods to enhance our measurement.

The accuracy and clinical applicability of devices that monitor EMG activity during static as well as dynamic movements are now being investigated by researchers like Rob. Clinically, I still primarily assess range of motion by eye observation, but I now take into consideration a few additional factors than before.

1. How far can they travel?
2. Is there any discomfort, stiffness, or restriction of movement?
3. How do they seem to be moving? Are they quite rounded or flat in the back? Do they utilise their hips and lumbar spine during range?

The issue might be obvious at times, but can sometimes be hidden. I recall Rob showing us a number of movies during the masterclass and asking us to explain whether we believed the movement was originating from the spine, the hips, or both. On some cases, excessive lumbar flexion seemed to be restricted lumbar flexion, or vice versa. Rob was essentially attempting to make the point that our eyes don’t always perceive clearly what is happening and where the movement is coming from, and that maybe equipment that measures EMG activity throughout various ranges of movement might help us make an evaluation. Consistency is key while doing assessments. Try to employ the techniques you chose in a repeatable way.

WHAT METHODS ARE AVAILABLE TO RESTORE A NORMAL FRR?

The next step is to attempt to identify the limiting reason after measuring the lumbar active range of motion and determining that the FRR is compromised. Is flexion difficult and constrained because the hips aren’t doing their share? What constraints on hip flexion, therefore, exist? Or, is the lumbar spine continuing to be in too much extension, and if so, why?

The movement pattern should always be taken into account as part of the overall evaluation. For instance, if a patient has hypermobility syndrome and overuses their lumbar spine, their mechanoreceptors won’t be engaged since their joints and ligaments aren’t stretched near the end of range. It seems sense that keeping these patients in flexion would not be the best course of action. Alternately, if a patient utilises excessive amounts of lumbar range due to stiffness in the posterior tissues of the hip that hinder hip flexion, repeatedly moving into flexion may not be the best course of action.

Therefore, you could target influencing elements including flexibility in the posterior hip components like calves, hamstrings, gluteals, and posterior chain. You could want to relax any tensed lumbar spine components that are causing it to remain in a relative extension. You might also attempt retraining your body to move in lumbar flexion. This last strategy may be used in a variety of ways.

According to some studies looking at the FRR, patients with low back pain frequently have overactive lumbar erector spinae muscles that hardly ever shut off. It is theorised that this overactivity leads to excessive spinal loading and altered tissue load-sharing capacity. Therefore, how are movement patterns in the lumbar spine now measured during evaluation if the FRR is a crucial component of movement into flexion and research have shown that it may be missing or altered?

Keep in mind that the fundamental goal of retraining flexion is to promote relaxation at the end of range. The workout posture is inappropriate if the patient is guarded or in discomfort. I usually start with the child’s position since it covers all the necessary factors, such as hip and lumbar flexion, and the floor supports the patient, enabling them to concentrate on breathing. The next phase is the sitting forward fold, where patients’ upper bodies are supported while they lay on their thighs after relaxation has been attained in this posture. once again concentrating on inhaling and exhaling. The last phase is to assume the position they first found offensive, which would be while still in the recovery process.

What if you can’t apply these approaches because the movement is painful?

Lumbar rotation is a terrific option, in my experience, if your client finds these motions too painful or unpleasant but you still think they need more lumbar erector spinae relaxation. The back muscles might be known to function bilaterally to provide extension and unilaterally to produce rotation. As a result, one side is activating and the other is relaxing as we spin from side to side. It’s an excellent place to start if you want to learn how to manage your breathing and relax your muscles in a pain-free posture.

Hopefully, this article has provided you with some fresh LBP treatment tools. It is nothing novel or flashy, just a powerful reminder to take your time to carefully and thoroughly evaluate the primary issue and the movement patterns around it.

It serves as a reminder to me that we must consistently connect evaluation and therapy and demonstrate the value of our interventions. We merely need to concentrate on using our clinical reasoning to choose the greatest therapy for the best patient as we continue to look for information and solutions. I really believe that this is a “watch this space” issue, and that soon we will have improved methods for measuring lumbar movement objectively, analysing the movement patterns we discover, and developing methods for normalising the flexion relaxation response.

Click here to learn more about Rethinking about Low back pain

References

1. Hu, B., Shan, X., Zhou, J., & Ning, X. (2014). The effects of stance width and foot posture on lumbar muscle flexion-relaxation phenomenon. Clinical Biomechanics, 29(3), 311-316.
2. Kim, M. H., Yi, C. H., Kwon, O. Y., Cho, S. H., Cynn, H. S., Kim, Y. H., … & Jung, D. H. (2013). Comparison of lumbopelvic rhythm and flexion-relaxation response between 2 different low back pain subtypes. Spine, 38(15), 1260-1267.
3. Laird, R. A., Kent, P., & Keating, J. L. (2012). Modifying patterns of movement in people with low back pain-does it help? A systematic review. BMC musculoskeletal disorders, 13(1), 1.
4. Neblett, R., Mayer, T. G., Brede, E., & Gatchel, R. J. (2014). The effect of prior lumbar surgeries on the flexion relaxation phenomenon and its responsiveness to rehabilitative treatment. The Spine Journal, 14(6), 892-902.
5. Zwambag, D. P., & Brown, S. H. (2015). Factors to consider in identifying critical points in lumbar spine flexion relaxation. Journal of Electromyography and Kinesiology, 25(6), 914-918. ( Image coutsey: google.com