Review of core stability exercise versus conventional exercise in the management of chronic low back pain

Exercise has been proven to be effective in the management of chronic low back pain. Over the years, core stability exercise (CSE) has gained popularity however there is lack of consensus on the best exercise treatment. Aims To review the effectiveness of core stability exercises or conventional exercises in the management of chronic low back pain (CLBP). Methods This study is a systematic review of randomized clinical trials which examined studies regarding core stability and conventional exercise by using Google scholar, Medline, PEDro and Cochrane from 2010 to 2021. The Methodological quality was evaluated using the PEDro scale. The included studies randomized participants into two different exercise groups. Results From the 58 potentially relevant trials, a total of 14 trials were included in the current analysis. The data indicated that core stability exercise was better than conventional exercise for short term pain relief. Ten studies included self reported back specific functional status, and compared to conventional exercise, core stability exercise resulted in significant improvement in function. Conclusion Compared to conventional exercise, core stability exercise is more effective in pain reduction and improved physical function in individuals with CLBP in the short term however, only two trials carried out follow-up assessments post intervention.


Introduction
Low back pain (LBP) is the single biggest cause of years lived with disability worldwide and a major problem to global health system. 1 Low back pain by definition is pain in the region between the lower margin of the 12 th rib and the gluteal folds with or without distal radiation to the lower extremity. 2 In western countries, the estimated lifetime prevalence of LBP ranges from 30% to 79.2% whilst the lifetime prevalence of low back pain in Africa ranged from 28% to 74% and was almost correspondent to the rates in the Western societies. 3 There is evidence that the prevalence and costs of LBP are rising around the globe due to ageing and expanding world population. 4 More so, it has been asserted that the risk of low back pain is twice as high once a history of the condition have been established. 5 Despite this, the most appropriate intervention to LBP remains elusive. 6 The causes of LBP are complex and not clearly understood; although some risk factors are implicated. 7 Individuals with LBP commonly present with decreased flexibility in the lumbar region and functional status. The latest clinical practice guidelines recommend that patients remain physically active, as long period of physical inactivity contributes negatively to recovery and the general wellbeing. 8 Many exercise techniques have been developed for the treatment of CLBP. Their aims are pain decrease, muscular strengthening in flexion or extension. 9 Core stability training is fast becoming a popular rehabilitation regimen in the management of CLBP, as it involves the restoration of the ability of the neuromuscular system to control and protect the spine from injury or re-injury. 10, 11 Bronfort et al 12 found that supervised core stability training improves pain severity, disability level and general health after some weeks of treatment. More so, a meta-analysis by Wang et al 13 found that core stability exercises produced better outcomes than routine exercise therapy during the initial three months of intervention for low back pain. Conventional exercise has been in use for long period of time and also has been established to be effective in pain reduction and improved strength. 14 Consensus on the most effective types of exercises for the treatment of CLBP has not been reached yet. Hence, the objective of the review was to investigate the effectiveness of core stability training and conventional exercise in patients with low back pain measured in randomized controlled trials on pain and disability outcomes.

Methodology Study Design
We conducted and reported this systematic review according to the PRISMA guidelines, with a protocol defined a priori. We identified randomized controlled trials (RCTs) by electronically searching the following databases: Physiotherapy Evidence Database (PEDRo), Medline, Cochrane, Google scholar, and others. Furthermore, we conducted a hand-searching of the reference lists of the articles found from the databases and journals to identify additional relevant articles. Briefly, the following medical subject headings (MeSH) were included: low back pain, sciatica, lumbo-sacral region, exercise, and chronic pain. We restricted our searches to only studies published in English language between the years 2010 to 2021. We arrived at the decision so as to eliminate the cost of language translations and to ensure that the identified and included articles in this review would not be studies that are too staled. The keywords used were RCTs, double-blind method, single-blind method, random allocation, pelvic girdle pain, motor control, exercise therapy, stability, stabilization, traditional exercise, conventional exercise, specific exercise, and physical therapy. We removed duplicates that were identified in multiple database searches. Reference lists of the included articles were also manually searched for relevant studies. All the literature searches in the afro-mentioned databases and journals were performed between March and August, 2021.

Inclusion Criteria
Literature search was conducted through several steps. First, the objective of this study was defined with population, intervention, comparison, and outcome (PICO) techniques. These techniques were determined to establish the eligibility criteria for this study as follows. Types of studies: Only RCTs examining the effects of core stability exercise versus conventional exercise for the treatment of patients with chronic LBP were included. Types of participants: We included articles with both female and male subjects (over 18 years of age) who had chronic LBP (longer than 3 months). We excluded articles that included participants with LBP evoked by specific conditions or pathologies. Types of interventions: We included articles that compared a control group, which received conventional exercise, and treatment group, which received core stability exercise training. A core stability training program could be described as the reinforcement of the ability to ensure stability of the neutral spine position. 10 Types of outcome measures: The primary outcomes of interest were pain intensity and back-specific functional status.
removed once inclusion criteria were not met. In conflicting situations, a third reviewer (Ogbonna Linda Nnenna) was consulted

Exclusion Criteria
Exclusion criteria were listed as follows: title keywords unrelated to research topics; unclear articles; and incomplete study, study protocols, abstract, and review articles.

Data Extraction
We extracted the following data from the included articles: study design, subject information, description of interventions between the core stability exercise and conventional exercise group, follow-up period, and outcome measures (Table 1). These data were then compiled into a standard table. The two reviewers (Nwodo Obinna and Onwudiwe Chukwudi) who selected the appropriate studies also extracted the data and evaluated the risk of bias. It was necessary to consult an arbiter (Ogbonna Linda Nnenna) to reconcile any disagreements. It is concluded that subjects in the group who received Core muscles activation exercises are more effective as compared to the group who received Conventional exercise in reducing pain, increasing the ROM and improving the disability.

Critical Appraisal Instruments
The Physiotherapy Evidence Database (PEDro) scale was the critical appraisal instrument used in this study. The tool comprised eleven elements, and each element required a dichotomous yes/no response: 1 point was given to yes and 0 was allocated to no. The total score for the PEDro scale was 10. PEDro scores were excellent (9-10), good (6-8), fair (4)(5), and poor (less than 4) Foley et al. 15

Risk of bias assessment
The risks of bias within and across the study were assessed by using the Cochrane Effective Practice and Organization of Care risk of bias tool (Cochrane Effective Practice and Organization of Care Group). 16 This tool comprised nine items, namely, random sequence generation, allocation concealment, similar baseline outcome, similar baseline characteristics, incomplete outcome data, blinding, contamination, selective outcome reporting, and other biases. All of the items were given a score of high risk, low risk, or unclear (Table 2).

Search Results
The process of identifying eligible studies was outlined in figure 1. One hundred and seventy-seven records were initially identified through the Cochrane, Medline, Google scholar, PEDro and others. Of these, 58 potentially eligible articles were included based on their title and abstract. After reviewing these 58 potential articles, only 14 articles fulfilled the inclusion criteria. [17][18][19][20][21][22][23][24][25][26][27][28][29][30] The remaining 44 articles were removed because the trials included was not randomized, did not compare core stability exercise with conventional exercise, or the original data were not available from the authors.   (4) Not randomized clinical trial (27) Unrelated topics (7) Did not fulfill intervention criteria (20) (n = 58)

Screening
Number of articles remaining after duplicates was removed Included studies Studies were included if they were RCTs on efficacy of core stability exercise and conventional exercises in CLBP management, published in English between 2010 and 2021. Included patients were between the age of 18 and 60 years. Below are the individual characteristics of the included studies.

Intervention
CSE is the exercise that involves the spine and core muscles (mostly the transversus abdominis or multifidus), where the core muscles are tightened to while the spine is being stabilized and then progressed to functional activity. 24 Conventional exercises are traditional exercises that are not specifically targeted to the core muscle of the spine. 24

Data synthesis/extraction
Data synthesis involved the combination and summary of findings of the studies selected for the review. The synthesis of the data was done by the descriptive synthesis using the extraction form designed by the reviewer to outline characteristics of the studies.

Data analysis
The selected studies for the review were appraised using the PEDro scale. The methodological quality of all selected studies for the review was strictly assessed by two independent reviewers (Nwodo Obinna and Onwudiwe Chukwudi) with blinding.

Outcome measures Pain Intensity
Twelve out of the fourteen included study assessed pain intensity using visual analogue scale, of the other two trials, one examined pain intensity using Numerical Pain Rating Scale and the other did not assess pain intensity (Table 4).

Disability
Ten studies included assessed disability level. Of these, seven used Oswestry Disability Index; two used Rolland Morris Disability Questionnaire and one utilized Quebec Low Back Pain Disability Index (Table 4).

Duration of intervention
The duration of the interventions in the studies included in this review were about 30 min per each session, twice a week for at least two weeks to twelve weeks.

Dropouts
Of the fourteen studies included, five reported dropout of participants during the study period (Table 5).

Core Stability Exercise versus Conventional Exercise on Pain Intensity
In total, fourteen trials were included in the study, twelve of which assessed pain intensity using visual analogue scale 17-24, 26, 27, 29, 30 one of the two trials examined pain intensity using Numerical Pain Rating Scale 25 and the other trial did not evaluate pain intensity 28 . The data indicated that core stability exercise was better than conventional exercise for short term pain relief. Only two trials out of the fourteen evaluated pain intensity at three months post intervention, and found core stability exercise to be more beneficial in pain reduction than conventional exercise.

Core Stability Exercise versus Conventional Exercise on disability
Eleven studies included self reported back specific functional status. 17

Discussion
This review, which included fourteen studies, 17-30 compared the effects of core stability and conventional exercises on chronic low back pain. The risk of bias was examined for each article using the Cochrane collaboration recommendations. The results of this review indicate that core stability exercise is better than conventional exercise for pain relief and improving back specific function in the short term however Intermediate and long-term effects were not determined as there were no follow-up periods beyond three months. The primary results of this review are consistent with the findings of a meta-analysis of core stability exercise versus general exercise for chronic low back pain. 13 The results of the meta-analysis indicated that core stability exercises are more effective than other types of exercise in improving back-specific functional status in the short term. Four other systematic reviews [31][32][33][34] also reported that specific stabilization exercise was better than ordinary medical care and treatment by a general practitioner for reducing pain over the short term and intermediate term. Compared to the prior reviews, all the articles included in the current study were new, spanning from 2010 to 2020, and all of the articles in the current analysis considered only patients with chronic LBP (duration of pain >12 weeks). Based on these characteristics, this review is considered to be robust. Core stability is the ability to control the position and movement of the central portion of the body. 35 Popular fitness programs, such as Tai Chi, Yoga, and Pilates, are based on core stability exercise principles. There are several different approaches currently in use for core stability exercise for LBP, which could lead to different results. A systematic review of different core stability exercises for LBP should be conducted to determine the optimal treatment approach.

Limitation
The quality of this review may have been affected negatively due to inability to include other studies that were reported in other languages other than English and the year of publication which was restricted to the year 2010 and 2021. Numerous articles did not contain adequate information for evaluating the quality and clinical relevance of the data. Another limitation was the probability of publication bias, which we attempted to diminish via a substantial database search. However, unpublished articles were not searched.

Conclusion
In this study, core stability exercise and conventional exercises for the lumbar region were both found to be beneficial in remission of pain and back specific function on chronic low back pain in the short term however; only two of these studies carried out follow up assessment for a period of three month which also showed that core stability was still more beneficial. Although this review may not be comprehensive however, it demonstrates deeper understanding of the use of core stability and conventional exercises in the management of CLBP.

Implications for Research
Articles that are methodologically sound and sufficiently powered are required to confirm the effects of core stability exercises and conventional exercises on pain relief and functional improvements in patients with chronic LBP. More so, the effects of core stability exercise and conventional exercises should be evaluated over a period of time post intervention.

Declaration of interest
There is no conflict of interest.

Source of Funding
None.