Introduction

Sure you’ve heard about the lumbopelvic rhythm and its relationship with low back pain. Without blaming it as a sole cause for low back pain, sometimes this can be a contributor to the multifaceted cause of chronic low back pain. The lumbopelvic rhythm describes the relationship between the low back and pelvis during forward bending and returning to an upright position. Most people will first bend in the lumbar spine and later on in the movement, the hips will contribute to the motion together with anterior tilting of the pelvis. When returning upright, first hip extension and posterior pelvic tilting would normally occur before the lumbar spine extends. Sometimes, people use more lumbar flexion range to bend forward and less in other joints such as the hip and knees. This altered movement pattern is often observed in people with low back pain and was found to be related to functional difficulties. The authors of this paper state that given the alteration in the movement pattern and the relatedness to functional limitations, it could be relevant to target the altered pattern during the performance of functional activities. Therefore they conducted this study where they compared motor skill training to change this movement pattern to a group receiving strength training and flexibility exercises.

Methods

Using kinematic data from a randomized controlled trial, this study included 154 individuals with chronic low back pain between 18-60 years. The participants had low back pain for at least 1 year but were not in an acute flare up and were otherwise healthy.

They were randomized into a group receiving motor skill training or into a group performing strengthening and flexibility exercises. The training was done during six weeks and involved 6 1-hour sessions once a week. The participants in the motor skill training program were taught to modify specific pain provoking movements and replace them with an alternative strategy.

“The primary objectives of treatment were to train the participant to (1) reduce the amount of early lumbar spine movement related to the participant’s LBP classification (e.g., flexion), (2) increase the movement of other joints (e.g., knees and hips) and (3) avoid prolonged end range alignments of the lumbar spine in the specific direction related to the participant’s LBP classification.”

For example (see image below): when a patient’s low back pain gets “classified” as a flexion problem, they try to modify daily activities involving those flexion movements. Basically, they try to avoid this movement. The same is true for all other directions.

The subjects in the strength and flexibility training group received specific exercises to strengthen all of their trunk muscles (according to the guidelines by the American College of Sports Medicine) and improve trunk and lower extremity flexibility in all directions.

Data were collected at baseline, at 6 weeks and at a follow-up at 6 months and included the three-dimensional coordinates to analyze the kinematics during a functional task which was picking up a light object.

Results

Not very surprisingly, the subjects in the motor skill training group showed increased angles of knee and hip flexion and decreased lumbar spine flexion when picking up an object while those in the strength and flexibility group did not. It was specifically taught to subjects in the motor skill training group to avoid forward flexion of the lumbar spine and use more range in the hips and knees. The group performing strength and flexibility exercises, where no focus lay on altering the movement strategy, received no such instructions. Therefore, this outcome seems very logical.

Questions and thoughts

When reading this paper, I sure get the clues why they focus on motor skill training to target the altered movement pattern they observe in people with low back pain performing functional activities. Although everyone may have different movement strategies and in my opinion, there isn’t a “bad” strategy, I understand that in some cases, teaching how to move “more optimal” to temporarily unload provocative structures for example, can be necessary.The problem I personally have with this paper when looking at the supplementary data is that they provide so much nocebo information (for example: “do not bend, twist or shift low back”) and break down complex movements into different steps, which may make it seem a bit robotic (see images below).

Is the fact that this pattern of decreased lumbar spine flexion was maintained over 6 months a good outcome? Personally I don’t think so. Our spine consists of strong joints and is able to bend forward. Why wouldn’t you move in a direction with a joint that is designed to make that movement? You can flex your knees and you use them also when you need to. To use a different movement pattern to temporarily unload a certain area, I certainly agree with. But to avoid a certain movement in daily life and maintaining this avoidance may induce fear-avoidance or kinesiophobia which is also very commonly seen in people with chronic (low back) pain. Therefore I would suggest not to focus on avoiding certain movements but I would rather try to optimize strength during that motion and control over that motion. 

Talk nerdy to me

This study was a planned secondary analysis of kinematic data from participants in a larger controlled trial. The power analysis was based on the primary outcome of the larger trial, not for the outcome studied here. The sample size was calculated for detecting a minimal clinically important difference of 6 points on the modified Oswestry Disability Questionnaire. No sample size was calculated for the kinematic data here. So this study used a subset of patients from their larger RCT in a preplanned secondary analysis, but to study the kinematics was not the primary objective and should therefore be interpreted with caution.

Take home messages

People often show different movement strategies to accomplish a functional task and that’s okay! However, when having low back pain, an altered movement pattern which uses only lumbar flexion may be provocative as often, the lumbar spine extensors may be too weak to eccentrically control the movement of the trunk. Temporarily unloading with some strategies used in this paper may be helpful. But I question the relevance of avoiding these movements and sustaining this altered avoiding movement pattern over time. Though interesting to read, I would recommend strengthening and empowering people with chronic back pain rather than teaching them how to avoid lumbar spine flexion.

Reference

Hooker, Q. L., Lanier, V. M., Roles, K., & van Dillen, L. R. (2022). Motor skill training versus strength and flexibility exercise in people with chronic low back pain: Preplanned analysis of effects on kinematics during a functional activity. Clinical Biomechanics, 92, 105570.