Introduction

As physios, we get many referrals of patients with back pain. Most of them are non-specific but in some cases, a specific pathology can be present. Disc herniations occur most often in the lumbar spine and can be associated with neurological symptoms radiating down the leg. This limits the ability of the person to participate in daily and work-related activities. To counteract this, physiotherapy is often prescribed. Many options are available to offer patients with disc herniations and motor control exercises are among them. The purpose of motor control exercises is to activate the stabilizing muscles of the spine to optimize the loading of the lumbar spine. The deep muscles of the trunk such as the multifidus, transversus abdominis, and pelvic floor muscles are recruited. Motor control exercises have been studied in low back pain, but to date, no meta-analyses have been conducted to examine these exercises in lumbar disc herniated patients.

Methods

This study examined the effectiveness of motor control exercises compared to other common interventions such as physical therapist-led interventions, surgery, and placebo/sham treatment in patients with symptomatic lumbar disc herniations. A systematic review was conducted to include clinical trials that compared motor control exercises to other common interventions such as general exercises, transcutaneous electrical nerve stimulation (TENS), surgery, placebo/sham, minimalist, or no intervention. The target population was adults with referred leg pain (with or without low back pain) caused by a lumbar disc herniation. Only true herniations were eligible for this study, thus disc bulgings were not included. The effectiveness of the motor control exercises was studied for the outcomes of pain and functional status.

The results of this study were expressed as mean and standard mean differences for pain and functional status respectively. Minimal important differences were defined as a mean difference of 15 for pain and 10 for functional status. A negative effect size indicates that MCT is more beneficial than comparison therapy, meaning that participants have less pain or fewer functional limitations.

Results

Sixteen trials were included in the meta-analysis, examining 861 patients in total over a period of median 10 months. The ages of the participants ranged between 29–65 years and the mean age was 54.38 (+/-9.81) years.

The results were subdivided into participants who had undergone a surgical procedure and those who didn’t. Considering pain reduction in patients who received surgery and did motor control exercises could improve pain levels in the short term when compared to other forms of exercise (MD -8.40 (95% CI -13.15 to -3.66)), but this effect was inconclusive in the mid-and long-term (mid-term MD -9.92 (-19.09 to -0.76); long-term MD -4.00 (-14.49 to 6.49)). The results for the mid-term are significant, though. Motor control exercises were not better than other physiotherapist-led interventions in the mid-term and long-term (mid-term MD -5.88 (-20.63 to 8.87); long-term MD-0.12 (-7.88 to 10.24)). It provides equal pain relief compared to surgery in the long run, in those who had had previous surgery for lumbar disc herniation (MD -1.20 (-13.66 to 11.26)). In the short-term, motor control exercises provided clinically important pain relief than when no intervention or minimalist intervention was provided or when the patient was self-managing, but the results were inconclusive. However, looking at the confidence interval, I would say that rather than the results being inconclusive, they are not significant (MD -19.50 (-41.77 to 2.76)). The authors state that “at intermediate-term and long-term, the findings demonstrated that motor control exercise results in non-meaningful pain reduction compared with minimal intervention, self-management or no intervention”. But when looking at the confidence intervals, we see that the differences are not significant, and thus also not clinically meaningful: (mid-term MD 5.03 (-3.84 to 13.90); long-term MD 1.18 (-7.88 to 10.24)).

Looking at functional status, according to the authors, results were inconclusive when comparing motor control exercises to other forms of exercise at the short- and intermediate-term (short-term SMD -0.95 (-1.32 to -0.58); mid-term SMD -0.77 (-1.32 to -0.22). However not clinically relevant, the differences here are statistically significant, thus I don’t quite understand why they label the evidence as inconclusive here. In the long-term, the motor control exercises were better than other forms of exercise, seen by the SMD of -2.49 (-3.19 to -1.78). Compared to other physiotherapist-led interventions, motor control exercises were statistically and clinically better at improving functional status to a large extent in the short-term (SMD -2.30 (-2.69 to -1.64)). At the mid- and long-term, the authors state that the evidence is inconclusive, however, the evidence is not significant, as seen by the confidence intervals (mid-term SMD -0.14 (-0.75 to 0.48); long-term SMD 0.08 (-0.31 to 0.46)). Motor control exercises are equal to surgery in the long-term (SMD -0.30 (-0.82 to 0.23)). But at the short-term, motor control exercises perform better to enhance function than no intervention, minimalist intervention, or self-management (SMD -1.34 (-1.87 to -0.81)).

Patients who did not undergo surgery had a large clinical and statistical reduction in pain when performing motor control exercises when compared to TENS (mean difference −28.85, 95% CI −40.04 to −17.66). There was no difference in pain reduction when comparing water-based or land-based motor control exercises in the short-term. A statistically significant difference in pain intensity was found between motor control exercises and general exercise in the intermediate- and long-term, but this difference was not clinically important (intermediate-term: MD −7.30, 95% CI −14.38 to −0.22; long-term: MD −8.20, 95% CI −13.75 to −2.65).

Considering functional status in those who did not undergo surgery, motor control exercises produced a large clinical benefit for improving function compared to receiving TENS in the short-term (SMD −1.98, 95% CI −2.57 to −1.40). Motor control exercises were not superior to other forms of exercise in the short-, intermediate- or long-term for improving function (short-term SMD 0.21 (-0.51 to 0.93); intermediate-term (SMD 0.04 (-0.46 to 0.53)). Yet, the confidence interval reveals that for the long-term the SMD was significant (SMD -0.83 (-1.35 to -0.31)). There was no difference in functional status when performing land- or water-based motor control exercises (SMD 0.37 (-0.46 to 1.20)).

Questions and thoughts

Fourteen studies were judged to have a high risk of bias and two studies had some risk of bias, which hampers the conclusions found by the review. Furthermore, the robustness of the findings was poor and the overall certainty of the evidence was very low to low. This means that future research will very likely change the outcomes. You can use motor control training in patients with lumbar disc herniations but don’t rely on this treatment alone. I think what is most important to take away from this piece of research is that motor control training may have positive effects in reducing pain and improving function in individuals who underwent or in those who did not undergo spinal surgery. It may be used along with other types of exercises and is a safe treatment option to use. The gains will be likely more expressed in the short term in those who did not have surgery, while the gains in those who had received surgery will be more pronounced in the long term.

What is interesting about motor control training is that it is performed in several steps: learning to perform segmental spinal stabilization, performing it while performing other movements, integrating it during functional movements and activities, and during whole-body movements. In this way, a progressive approach is used to adapt the patient to different functional activities, moving from supine to simple activities and eventually to demanding functional movements needed in daily life. I believe that it is not so much the effect of the motor exercises that causes improvements in pain and functional status. Rather, in my opinion, the beneficial effect is the result of the progressive approach used to return the patient with a symptomatic lumbar disc hernia to participation in his or her ADL. As with any injury, you start slowly and progress to functional activities that demand a lot from you, right? So perhaps you don’t need to stick to the holy grail that is “motor control exercises for spinal stabilization,” but can see this type of training more in the light of progressive rehabilitation and reintegration of functional activities. Many studies did not go into these progressions, unfortunately, and perhaps there may be more room for improvement when this is done in further studies.

Talk nerdy to me

Apart from what I already mentioned about the very low to low certainty of evidence, the methodology of this review was performed according to the rules. The results have been restricted to only those patients who had lumbar disc herniations, thus a displacement of the nucleus pulposus through the annulus fibrosus. So, disc bulgings were not considered here, which is important to note when interpreting these results and the implications of the evidence for your clinical practice.

Take home messages

Patients who undergo surgery may benefit from performing motor control exercises to improve pain in the short-term and intermediate-term compared to performing other forms of exercise and to improve functional status in the short–, intermediate– and long-term, compared to other exercises. Motor control training outperforms other physiotherapist-led interventions at the short term and is better than performing no intervention, a minimalist intervention, or self-management.

When patients do not receive surgery, motor control training produces large effects in pain reduction in the short-term and functional improvement compared to TENS. Doing motor control exercises can reduce the pain more than compared to general exercise in the intermediate- and long-term, but is equal to the outcomes of other exercises in the short-, intermediate- and long-term.

However, the only clinically meaningful reduction in pain was obtained when motor control exercises were compared to TENS in the short term, as seen by the mean difference that was larger than the predefined MCID of 15 for pain. Unfortunately, the level of evidence here was low and the robustness of this result was not confirmed.

Reference

Pourahmadi M, Delavari S, Hayden JA, Keshtkar A, Ahmadi M, Aletaha A, Nazemipour M, Mansournia MA, Rubinstein SM. Does motor control training improve pain and function in adults with symptomatic lumbar disc herniation? A systematic review and meta-analysis of 861 subjects in 16 trials. Br J Sports Med. 2022 Jun 14:bjsports-2021-104926. doi: 10.1136/bjsports-2021-104926. Epub ahead of print. PMID: 35701082.