The effects of CORE exercises on Chronic Low Back Pain: A (small) Review
Osteopathic medicine is a medical system of diagnosis and therapy based on manual techniques, preaching a holistic approach (Orrock & Myers, 2013), ultimately seeking auto-regulation and equilibrium in all physiological systems of the human body. Albeit the capacity of treating and helping a wide spectrum of problematic, from digestive issues to chronic fatigue, osteopathic treatments are primarily undertook for musculoskeletal and somatic dysfunctions, such as low back pain (LBP). Indeed, LBP has been identified as one of the most prevalent reason of consultation to osteopathic clinicians, highlighting the essential need in understanding this condition (Orrock & Myers, 2013). The pertinence of understanding and researching LBP can also be supported by its high incidence in the general population, up to 50% to 80% in one’s lifetime (Park & Yu, 2013; Lamba et al., 2013; Khan et al., 2014). In addition to this observation, it is proposed that 70% to 80% of acute low back pain sufferers will experience at least one recurrence, potentially leading to chronic low back pain (CLBP) (Chon, You, Saliba, 2012; Norris & Matthews, 2008). Such epidemiological numbers sheds light on the importance of treating and exploring the multiple therapeutic options concerning this particular condition.
Chronic low back pain is the second most common reason for absenteeism from work and the most common reason of medical consultation (Franca et al., 2012). Indeed, CLBP affects over 50% of the general population (Rozemberg, 2008). A wide range of therapeutic approaches exist when treating chronic low back pain, but the literature does not point towards one specific best single approach (Wang et al., 2012). Among the available approaches, exercise is commonly used in managing chronic musculoskeletal conditions, and CLBP is not an exception (Panjabi, 1992). Exercises are indeed the central foundation of many approaches, such as physiotherapy. An emerging theme in exercises for CLBP and LBP, has been the prescription and application of core exercises. The core can be briefly defined as an area circumscribed by the abdominals in the front, paraspinals and gluteals in the back, the thoracic diaphragm as the roof, and the pelvic floor and hip girdle musculature as the bottom (Richardson, Jull, Hodges, Hides, 1999). The basis behind the importance of the core for preventing and treating CLBP is based on a classic paper published by Panjabi, describing a biomechanical model of CLBP (Panjabi, 1992). This model, on which core exercises anchor themselves, assumes that pain recurrence is caused by repeated mechanical irritation of pain sensitive structures and therefore proposes that improved control stability of the lumbar spine will lead to a reduced mechanical irritation and subsequently lead to pain relief (Panjabi, 1992). The approach of core exercises therefore aims in improving neuromuscular control, strength and endurance of muscles in order to maximize the stability and the complex dynamic of the lumbar spine and the pelvis (Standaert, Weisten and Rumpeltes, 2008; Panjabi, 1992; May & Johnson, 2008; Richardson C, Jull G, Hodges P, Hides , 1999).
This present review, will precisely aim in determining the effect of core exercises on chronic low back pain. The intent of such a review takes place in an evidence-based approach, a medical paradigm that has been seen as essential in giving credibility to osteopathic medicine. From that main question, a secondary question will be developed on how can the state of knowledge recovered in the literature about the effect of core exercises on chronic low back pain be utilized by osteopathic clinicians in order to help patients.
Defining the Core
Core training has emerged as a major trend in LBP management and prevention. The term core training, or core exercise, can translate into lumbar stabilization and motor control around the lumbar region to maintain functional stability of the spine (Akuthota & Nadler, 2004). Concretely, the term “core” refers to an anatomical frame, or box, constructed by the abdominal muscles in anterior, the para-spinals and gluteal muscles in posterior, the thoracic diaphragm in superior, and the pelvic floor and hip girdle musculature caudally (Akuthota & Nadler, 2004; Standaert, Weisten and Rumpeltes, 2008). The core concept can therefore be understood as a muscular corset preserving and optimizing body and spine stability, with or without limb movement (Akuthota & Nadler, 2004).
Even though the core consists of many muscles, as mentioned above, core training protocols tend to focus on two specific groups of muscles, the paraspinals and the abdominals. The paraspinals can be divided into two major groups consisting of the erector spinae muscles, and the smaller and more local muscles such as the rotators, intertransversi and multifidi muscles (Akuthota & Nadler, 2004). In the lumbar region, the erector spinae muscles are formed by the longissimus and iliocostalis. Through their connection to the pelvis via tendinous attaches, a long moment arm is formed, explaining their capacity to create great force and shear in that specific area (Akuthota & Nadler, 2004). The smaller muscles of the lumbar spine lay deeper and more medial to the eractor spinae. Both multifidi and intertransversi muscles have a small moment arm, translating into stabilization functions, consistent with high levels of muscle spindles found in these muscles (Akuthota & Nadler, 2004). Out of the three layers of abdominal, the transversus abdominus receives the most attention. Considering its fibers running horizontally around the abdomen its contraction allows a “hoop-like” stress on that region and can be achieved through “hollowing-in” of the abdomen. With the internal and external oblique, the three layers of abdominal muscles increase intra-abdominal pressure with contraction, augmenting functional stability of the lumbar spine (Akuthota & Nadler, 2004).
Defining chronic low back pain
Chronic low back pain is of very high prevalence in all industrialized countries, affecting more than 50% of the population (Rozemberg, 2008), and is a major health issue considering its physical, psychological and economical burdain (Rozemberg, 2008; Kumar, Sharma,Negi, 2009; Froud et al., 2014). Low back pain is a general term and can be defined as acute (less than 6 weeks), subacute (6-12 weeks) and chronic (12 weeks +)(Rozemberg, 2008; Kumar, Sharma, Negi, 2009). Therefore, chronic low back pain is well accepted to be defined as a period of pain lasting for longer than 3 months. Depending on the area of health care, it is important to understand that LBP can be titled as lumbago, hyperextension injury, facet joint disorder or degenerative disc problems (Kumar, Sharma, Negi, 2009).
Types of training
Across the literature, it is observed that interventions focused on the core consist of primarily three types of exercises; stabilization exercises, strengthening exercises and stretching exercises. Stabilization exercises classically refer to isometric contractions that can be defined as a generation of force without muscles fibers length change (Tortora and Grabowski, 1993). Strengthening exercise consist of exercises based on concentric contractions or eccentric contractions, a generation of force through shortening of muscle fibers or lengthening of fibers, respectively (Tortora and Grabowski, 1993). Stretching is a type of physical exercise that aims in improving elasticity of muscles and soft tissues through elongation of fibers, leading to more comfortable muscle tone and increased muscle control, flexibility and range of motion (Tortora and Grabowski, 1993).
Concerning studies administrating stabilization exercises (Franca et al., 2012; Norris & Matthews, 2008; Moon et al., 2013; Lamba et al., 2013; Chown et al., 2008; Hosseinifar et al., 2013; Kumar, Sharma, Negi, 2009; Cairns, Foster, Wright, 2006; Ferreira et al., 2007), more than half focused specifically on the transversus abdominus and lumbar multifidi muscles (Franca et al., 2012; Chown et al., 2008; Hosseinifar et al., 2013; Cairns, Foster, Wright, 2006; Ferreira et al., 2007). It is proposed that specific stabilization exercises of these deep core muscles lead to motor learning and programming which is impaired in patients suffering from CLBP (Millistotter, 2007, cited by Hosseinifar, 2013). Indeed recent evidence suggests that patients with CLBP demonstrate deficits in proprioception and trunk motor control (Lamba et al., 2013). These functional handicaps may therefore lead to stress and inadequate load on the joints, ligaments and the spine, leading to pain (Lamba et al., 2013). This approach therefore bases itself on the biomechanical model of LBP developed by Panjabi (1992), where increased stability of the lumbar spine would be beneficial to CLBP patients. In other words, this approach aims in improving neuromuscular control, strength and endurance of core muscles, central to the dynamic spinal and trunk stability (Moon et al., 2013; Franca et al., 2012; Cairns, Foster, Wright, 2006).
Studies approaching the core through strengthening (Norris & Matthews, 2008; Moon et al., 2013), either in their intervention group or comparative group, bases itself on evidence demonstrating that patients suffering from CLBP demonstrate biomechanical, neurophysiologic and histochemical dysfunctions, such as muscular atrophy, ipsilateral to the painful level of pain (Mcdonalds et al., 2006, cited by Franca et al., 2012). Strengthening of these targeted muscles would therefore theoretically lead to muscle hypertrophy, hence counter balancing the atrophy occasioned by the CLBP and ultimately lead to reduced symptoms.
Finally one study also intervened through core stretching (Franca et al., 2012). Such an intervention may lie on the premiss that CLBP patients have been observed to present reduced flexibility and mobility in all planes of motion (McGregor et al., 1995) and that individuals with low back pain demonstrate decreased flexibility in the lumbar region with a positive correlation between these two variables (Thomas et al., 1998).
Core stabilization effects on chronic low back pain
When it comes to the effect of stabilization, or isometric contractions, of core muscles on chronic low back pain and functional disability caused by CLBP, the literature demonstrates that such exercise relieve pain (Franca et al., 2012; Norris & Matthews, 2008; Moon et al., 2013; Chown et al., 2008; Hosseinifar et al., 2013; Lamba et al., 2013; Kumar, Sharma, Negi, 2009; Cairns, Foster, Wright, 2006; Ferreira et al., 2007) and improves functional disability (Franca et al., 2012; Norris & Matthews, 2008; Moon et al., 2013; Chown et al., 2008; Hosseinifar et al., 2013; Lamba et al., 2013; Kumar, Sharma, Negi, 2009; Cairns, Foster, Wright, 2006; Ferreira et al., 2007). It is important to note that among these nine studies, three combined a variety of interventions increasing the difficulty to attribute the statistically significant result solely on core stabilization exercises. Indeed, the intervention group of Norris & Matthews (2008) received a combination of postural exercises, core stabilization and strengthening exercises, and technique specific exercises, divided in a three-stage process. A home stretching program combined with stabilization exercises was used by Chown et al., (2008) while Cairns, Foster and Wright (2006) combined physiotherapy treatments with stabilization exercise.
Exercise protocols consisted of ground stabilization exercise with the exception of Lamba et al. (2013) and Moon et al. (2013) who also utilized Swiss exercise balls to perform stabilization exercises. Specific muscles consisting of the transversus abdominus, and multifidi muscles were targeted in the majority of the studies (Franca et al., 2012; Norris & Matthews, 2008; Moon et al., 2013; Hosseinifar et al., 2013; Lamba et al., 2013; Kumar, Sharma, Negi, 2009; Cairns, Foster, Wright, 2006; Ferreira et al., 2007). Less common in the exercise protocols was pelvic floor stabilization exercises (Moon et al., 2013; Hosseinifar et al., 2013; Ferreira et al., 2007) and thoracic diaphragm exercises (Ferreira et al., 2007).
In addition to improved pain and functional disability, muscle thickness of the transversus abdominis is increased by core stabilization exercises (Franca et al., 2012; Hosseinifar et al., 2013), potentially showing the effectiveness of such exercises in reversing the muscular atrophy found in CLBP patients (Mcdonalds et al., 2006, cited by Franca et al., 2012).
Stabilization exercise show also increased strength of lumbar extensors, erector spinae, and lumbar flexors. When compared to strength training of the same muscle groups, increased strength in the lower amplitudes of flexion, 0o to 12o, is statistically higher in the core stabilization group (Moon et al., 2013), where an augmentation of the mean ± standard deviation changed from 92.6 ± 58.0 to 137.5 ± 62.4 in the 0o group and 115.6 ± 62.9 to 168.5 ± 67.9 in the 12o group.
Core strengthening effects on chronic low back pain
Experimental protocols exploring the effects of core strengthening exercises on CLBP demonstrate positive results on both pain and functional disability (Norris & Matthews, 2008; Moon et al., 2013). In Moon et al. (2013), strengthening exercises increase strength of lumbar extensor muscles and lead to reduced LBP. A total of 14 exercises were administrated, focusing on the activation of the erector spinae and rectus abdominis muscle groups. As of Norris & Matthews (2008), notwithstanding the core strengthening exercise, a combination of intervention ranging from physiotherapy taping to posture correction was realized making it once again difficult to specifically attribute the positive results of the study to the strength training of the core muscle groups.
Core stretching effects on chronic low back pain
Only one study examined the effect of core stretching on CLBP and functional disability, and demonstrated that such an exercise program significantly relieved pain and reduced functional disability (Franca et al., 2012). Stretching focused on the erector spinae and connective tissues of the posterior vertebral column. In addition, lower limb muscle stretches such as the hamstrings and triceps surae were administered (Franca et al., 2012). The exercise protocol was a combination muscular stretching and stabilization exercises, and yielded positive results in regards to pain and functional disability. Considering the mixed nature of this study, attributing these significant results solely to the stretching is difficult.
Osteopathy and chronic low back pain
A historical randomized control trial, known as the Osteopathic Trial, examined the effect of osteopathic manual techniques on chronic low back pain was conducted in 2013. This very rigorous study opted for a randomized, double- blind, sham-controlled, 2 × 2 factorial design, dividing the 455 participants into two intervention groups consisting of a group reporting low baseline pain severity, and a group reporting a high baseline pain severity (Licciardone, Kearns, Minotti 2013). The protocol consisted of six, 15 minutes, osteopathic manual techniques sessions provided every two weeks by the same osteopathic physician. Treatment techniques consisted of high-velocity, low-amplitude techniques; articulatory and soft tissue techniques; myofascial stretching and release; strain-counterstrain; and muscle energy techniques. The control, or sham treatments, consisted of active and passive range of motion, light touch, improper patient positioning, purposely-misdirected movements, and diminished force (Licciardone, Kearns, Minotti 2013). The study revealed a large effect size for osteopathic manual techniques versus sham treatments in providing LBP improvements for patients reporting high baseline pain severity. Improvement in back-specific functioning was also revealed. Such result suggests that osteopathic manual techniques provide a solution to care for patients with severe chronic low back pain.
In a study comparing an exercise group, a physiotherapy group and an osteopathy group, and its effect on CLBP, osteopathy was seen to be effective in relieving pain and improving functional disability (Chown et al., 2008). The osteopathic care consisted in soft tissue massage, tissue inhibition, muscle energy, high velocity low amplitude manipulations and articulation mobilization. In contrast to the osteopathic trial, the osteopathic treatments also included exercise, psychosocial and nutritional advices. An interesting observation was to note that the lowest dropout rate was seen in the osteopathy group, when compared to the two other intervention groups. All three-intervention groups demonstrated to be effective, but the study did not provide any evidence that any one single therapy offers therapeutic advantages over the others (Chown et al., 2008).
Understanding the literature (what does it mean?)
Across the literature, the data gathered from the analyzed studies unanimously point toward the same direction; core exercises benefit patients suffering from chronic low back pain. All three types of observed exercises (stabilization exercises, strengthening exercises and stretching exercises) yielded positive results in both perceptions of pain and functional disability.
Specific to the stabilization exercises, it was observed that such exercise increase muscle thickness of the TrA (Franca et al., 2012; Hosseinifar et al., 2013) and may prove to be important in resolving chronic low back pain considering the muscular atrophy observed in this population (Mcdonalds et al., 2006, cited by Franca et al., 2012). Measurement tools used by Franca et al. (2012) were said to be questionable. Indeed, ultrasound imaging was not used compared to Hosseinifar et al. (2013), making the results obtained by Franca et al. (2012) possibly less valid. Nonetheless, it is fair to advance that this type of exercise may therefore possess an advantage over the two other forms of exercises, considering this added benefit of muscle hypertrophy.
Although all studies demonstrated the benefit of core exercises on chronic low back pain, it is primordial to note that comparative groups included in these studies also achieved positive, significant results. Indeed, physiotherapy, osteopathy and general exercise regimens may also be adequate solutions for chronic low back pain and must be considered in the optic of pain management. It seems clear that considering the wide array of tools available to deal with chronic low back pain, the best option remains unique for every individual and a holistic and personalized approach must be considered. The same observation is concluded by (Lederman, 2010) which concludes that although core stabilization exercises are emerging as the preferred solution to health care practitioners, such types of exercises are as effective as general body exercises, for example.
The explication behind the effectiveness of core exercise on chronic low back pain possibly resides in the hypertrophy and neuromuscular adaptation engendered by these exercises. Such exercises would reduce lumbar load and lead to improvements in the quality of movements and coordination of trunk muscles (Hosseinifar et al., 2013). These explication fall in suit with the classic paper by Punjabi, explaining that lower back pain recurrence is caused by repeated mechanical irritation of pain sensitive structures and that disappearance of this chronic low back pain could be obtained through improved control stability of the lumbar spine (Punjabe, 1992). The efficacy of core exercise regimens therefore holds its premiss to the improved neuromuscular control, strength and endurance of core muscles, maximizing the stability of the complex dynamic of the lumbar spine and pelvis (Standaert, Weisten and Rumpeltes, 2008; Panjabi, 1992; May & Johnson, 2008; Richardson C, Jull G, Hodges P, Hides, 1999).
Osteopathy and core exercises
Osteopathic practitioners preach a holistic approach, where all spheres of a patient’s life are taken into account when trying to resolve a specific problematic. Indeed, this global care that offers osteopathic medicine may partly be a key to its success and appreciation. Interestingly, Chown et al. (2008) recorded that patient satisfaction was greater in one on one therapy, seen in osteopathy and physiotherapy. In addition to greater satisfaction, the dropout rate was the lowest in the osteopathy group, suggesting the appreciation of patients for this therapeutic option (Chown et al., 2008). Considering this apparent respect and appreciation from patients, osteopaths have the responsibility to provide the best and up-to-date care as possible.
When considering the global approach that is intrinsically part of osteopathy, it is easy to understand the importance of home exercise as part of an osteopathic practitioner’s role in providing a complete therapeutic care. As demonstrated in the Osteopathic Trial, osteopathy is effective in relieving chronic low back pain, especially in patients with high intensity baselines (Licciardone, Kearns, Minotti, 2013). Considering the presence of somatic dysfunctions and neuromuscular imbalance observed in chronic low back patients (Licciardone & Kearns, 2012), the efficacy of osteopathy in relieving chronic low back pain may be due to the ability to normalize these somatic dysfunctions. Indeed somatic dysfunctions were particularly observed in the lumbar, sacrum and pelvic regions. The severity of the somatic dysfunction in the lumbar region was directly associated with the severity of the pain, and back-specific disability. The severity of sacrum and pelvis dysfunction were directly associated with back-specific disability, and inversely associated with general health (Licciardone & Kearns, 2012).
The capacity for osteopathic practitioners to identify somatic dysfunctions and normalize them, leading to relieved pain, seems clear. Considering the dynamic nature of the body, it is possible to propose the importance for an osteopathic practitioner to find tools to maintain these improvements, and even potentialize these improvements over time. Home core exercise may therefore become an important aid, in the multifactor nature of pain and road to health. This statement takes even more strength when recalling the ability of core exercise to engender neuromuscular adaptations (Standaert, Weisten and Rumpeltes, 2008), and recalling the presence of neuromuscular imbalances in CLBP patients (Licciardone & Kearns, 2012).
The combination of augmented structural mobility of the lumbar, sacrum and pelvic region through the normalization of somatic dysfunction (Licciardone & Kearns, 2012) offered by an osteopathic treatment and the neuromuscular adaptation that offers core exercise theoretically sounds like a sound and effective course of action. Examining this combination through rigorous methodology and an appropriate research model would be beneficial for both the medical and the osteopathic world considering the prevalence of chronic low back pain, its impact on quality of life, and its associated economical, and therefore, societal burden.
Many factors limit the validity and strength of the conclusions that can be made by this literature review. Indeed, an important portion of the analyzed studies (Franca et al., 2012; Norris & Matthews, 2008; Chown et al., 2008; Cairns, Foster, Wright, 2006) included mixed intervention protocols, making it impossible to attribute the totality of the positive results to the core exercises. Ideally, studies including only core exercise as the independent variable would of increased the strength of the conclusions offered by this review.
Furthermore, the totality of the studies used mixed groups of subjects with non-specific chronic low back pain. Non specific low back pain can be defined as low back pain not attributable to a recognizable, known specific pathology such as infection, tumor, osteoporosis, fracture, structural deformity, inflammatory disorder, radicular syndrome, or cauda equina syndrome (Balagué et al., 2012). No study medically assessed its participants with adequate tools to certainly exclude all possible participant suffering from low back pain caused by one of the mentioned examples above. The feasibility of such a protocol is very difficult, considering the cost of such diagnosis tools (e.g: Magnetic Resonance Imaging), but would of helped to augment the quality and validity of these studies. Studies opted for exclusion criterions that were very heterogeneous, from researcher to researcher. Exclusion criterions ranged from rheumatologic pathologies, history of back surgery, previous physical therapy for the lower back, spine infections and systemic pathologies. Considering these mixed groups, the studies do not have the ability to determine if there is a specific subgroup of the population that react better, or worse to the core exercise regimen. Studies with more homogeneity in the experimental groups would have permitted an increased validity of the proposed conclusions made by this literature review.
In addition, no studies opted for a control group, making it impossible to assess the possible contribution of spontaneous improvement over time. Considering the nature of the participants, a population suffering from low back pain for more than 3 months, it is plausible to think that the research teams opted for no control group since the chronic nature of the low back pain may result in very low spontaneous improvement rates. Nonetheless, a control group would of controlled this possible factor, and increase the strength of these studies.
Conclusion (A lazy reader? read THIS)
Identified as the most prevalent reason of consultation to osteopathic clinicians (Orrock & Myers, 2013), low back pain is a complex and contemporary issue. Indeed, not only does it have an incidence of up to 80% in ones lifetime (Park & Yu, 2013; Lamba et al., 2013; Khan et al., 2014), it is the most common reason for absenteeism from work and the most common reason of medical consultation (Franca et al., 2012). Among therapeutic options available to resolve low back pain, and more specifically chronic low back pain, core exercises have been emerging as popular options to health care workers (Lederman, 2010).
Analyzing the literature discussing the clinical validity of core exercise for chronic low back pain has put into light its apparent efficacy in relieving pain and diminishing functional disability. All three types of core exercises consisting in core strengthening, core stabilization and core stretching, have demonstrated to be effective. Core stabilization exercises, specifically, have also shown to engender muscles hypertrophy of deep abdominal muscles such as the transversus abdominus and increased strength in the lower amplitudes of flexion, 0o to 12o, of the lumbar flexors, extensors, and erector spinae.
Putting all therapeutic approaches in perspective, studies point out that physiotherapy, osteopathy and general exercises also emerge as valid and effective options to help chronic low back pain sufferers. However, it was shown by Hodges (2003) that the rate of recovery was significantly higher with core exercise when compared to conventional treatment, demonstrating a possible advantage of using core exercise as a mean of management chronic low back pain.
Considering our sedentary lifestyle and the prevalence of chronic low back pain, more research on the subject needs to be accomplished. The future of this field of research may reside in identifying the specific subgroups most prone in benefiting from core exercises, and identifying the most effective exercises, and the optimal dose, duration, frequency, and progression of these exercises. Indeed, identifying the specific subgroup of chronic low back patients most reactive to core exercises would certainly help health care workers administer adequate and coherent exercise programs for every individual. Identifying the optimal dose, duration, frequency and progression of core exercise would also allow a quicker and smoother road to health and pain free living. These new findings could be achieved through randomized controlled trial research models, a model providing high levels of proof and rigor.
All in all, this literature review revealed the efficacy of core exercise for chronic low back pain patients. This state of knowledge may therefore permit osteopathic practitioners to prescribe home core exercise programs, with the assurance that such a prescription is evidence based, and effective.
Written by Antoine Del Bello
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