- Once termed “spinal stabilization”, core strengthening applies to the trunk, transversus abdominis, quadratus lumborum, and paraspinals including the multifidi; secondary muscles include internal and external oblique and pelvic rotator muscles.
- Strengthening increases intra-abdominal pressure acting as a natural corset protecting the spine. The goal is to prevent or reduce spine-generated pain.
- Weak core strength correlates with spinal injuries, yet causation remains unclear.
- Rantanen1 found multifidus weakness in persistently symptomatic patients up to 5 years after lumbar surgery.
Epidemiology including risk factors and primary prevention
- Three-year prevalence of back pain is estimated to be 67%.2
- Lifetime prevalence of back pain may approach 98%.2
- Important risk factors of back pain2
- poor socioeconomic status
- jobs with manual lifting/repetitive strain
- Cady’s study on firefighters with back pain reported that those who were more physically fit missed less work.3
- A Cochrane review reported that post-treatment exercise programs prevent back pain recurrence. 4
- Dysfunction of the multifidus, transversus abdominis, and erector spinae muscles in neutral lumbar range of motion (ROM) is associated with LBP.5
- Lack of flexibility in the lower limbs may cause dynamic pelvic asymmetry and change the optimal core muscle length causing reflex inhibition of spinal stabilizing muscles.
Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time)
- Many spinal injuries respond to core stabilization, particularly in patients with a relatively unstable or flexible spine/segment.
- Spinal pain may be axial, referred to the extremities (radiculopathy), or both.
- Most acute spinal pain related to strains/sprains and disc related pathology improves dramatically within 2 to 4 weeks.
- As many as 35% have pain after 12 weeks (subacute) and 10% have pain after 1 year (chronic).6 Additionally, 75% have at least one relapse within one year if no rehabilitation was performed.4
Specific secondary or associated conditions and complications
- Assessment of systemic symptoms to rule out other pathology or benign non-spinal conditions is essential.
- Spinal instability related to congenital and/or acquired spondylolisthesis may cause spinal cord or nerve root compression and subsequent neurological injuries.
- Normal neurological examination ensures that there is no progressive neurological motor or sensory loss.
2. ESSENTIALS OF ASSESSMENT
- Pain assessment includes
- exacerbating or remitting movements (may help direct treatment)
- Red flags include fevers, chills, and weight loss
- Neurologic considerations: weakness, numbness, bladder or bowel dysfunction, impaired balance
- Consists of complete neurologic examination including reflex examination, manual muscle and sensory testing.
- Assess alignment, posture, biomechanics and asymmetries of the lumbosacral spine and pelvis.
- Palpation often localizes the pain to the vertebral body, facet joint, sacroiliac joints, iliolumbar ligaments, or lumbar paraspinals.
- ROM localizes areas of tightness in the lumbar, pelvic, and lower extremity muscles and confirms any positional bias.
- Manual strength testing of the core musculature identifies reflexively weak or inhibited muscles.
- Exam findings can guide the exercise program, including determining if core strengthening will be useful.
- Assess functional limitations related to the spinal disorder by testing single leg squat to assess for core and hip girdle weakness or plank duration and technique.
- Chronic spinal pain can adversely affect vocational and avocational activities, cause depression, and result in reduced social interaction.
- Tests that may help rule out non-spinal causes of pain include serum protein electrophoresis (SPEP), anti-nucleotide antibodies (ANA), rheumatoid factor (RF), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), thyroid stimulating hormone (TSH), Vitamin B12, and HLA-B27 serology.
- X-rays including AP, lateral, and flexion/extension views can show conditions such as spondylolysis, spondylolisthesis, scoliosis, spondylitis, compression fracture, and narrowing of disc spaces.
- Magnetic resonance imaging (MRI) is best for evaluation of discs, spinal nerves and spinal canal, and screens for malignant conditions including infection, fracture, and tumor.
- Computerized tomography (CT) may show bony pathology in greater detail than MRI; myelography is useful if MRI is contraindicated.
- Bone scan can reveal inflammation, infection, metastasis or fracture.
- All radiographic abnormalities must be correlated to the clinical examination.
Supplemental assessment tools
- Electrodiagnostic studies may improve accuracy when numbness or weakness are present or when complaints are not verified by physical exam or imaging.
- When it is unclear what functional impact the spine injury produced, a functional capacity examination (FCE) can quantify the level of disability related to the impairment and can reveal deficits that define restrictions/limitations on vocational activities.
Early predictions of outcomes
- Many studies have found improved outcomes in both acute and chronic lumbar pain with exercise therapy7.
- Spinal pain can compromise a person’s dignity and social status, with treatment implications decreasing compliance, particularly with active treatments.
- Core stabilization can encourage a return to an “active” state and allow patients to take control over their treatment and recovery.
- Society ultimately gains when a person with disability associated with spine injury is strengthened and recovers function to re-engage in household and work activities.
Core strengthening treatments implies the patient take an “active role” in their treatments. As the physiatrist it is challenging to get the patient “on board” when they might be used to passive treatments for other illness and conditions. Therefore, a multidisciplinary approach to treatment may be best for certain individuals.
3. REHABILITATION MANAGEMENT AND TREATMENTS
Available or current treatment guidelines
- Empiric approaches
- After initial assessment of posture and position, the goal is to find the position that produces the least pain, that is, “spine neutral.”
- From that position, tight muscles are stretched, to gain flexibility.
- Isometric core strengthening, such as planks and bridging exercises, should start next, to minimize exacerbating the pain.
- The intensity of the core strengthening should increase over time to include concentric and eccentric (alternating) abdominal strengthening and multifidus strengthening. More aggressive approaches include pelvic tilt, “dead bug,” and “superman” exercises.
- An exercise ball can then be introduced for neuromuscular re-training. Patients can lie on the ball and do arm and leg raises while at the same time contracting the abdominal core muscles.
- Finally simulation of functional activities (work or sports) and proprioceptive retraining completes the program.
At different disease stages
- New onset/acute: the most pressing need might be direct pain relief. Physicians typically employ adjunct pain-reducing medications or injections. Therapists can add therapeutic heat/cold or manual therapies. Finding the neutral spine becomes critical.
- Subacute: Usually the patient has acquired more self-awareness to perform the therapeutic exercises. One list of exercises could include isometric trunk tightening, reverse crunches (eccentric), oblique crossing over crunch, air bicycling, prone extension with and without stabilization ball, prone lower trap lift, seated upward row (on ball), and “buttlift.” Proprioception exercises come next with balance/coordination, then sport- or work-specific exercises, often with plyometrics and Pilates training.
- Chronic/stable: Pain may respond to any of the above, but deconditioned patients require a more gradually applied, often quota based, program. The goals of therapy often change to a more palliative or function based approach designed to teach strategies for the chronic pain patient to better perform activities of daily living.
- Pre-terminal care: patients with pain due to metastasis or fracture can sometimes benefit from gentle isometric exercises that improve function.
Coordination of care
- Core strengthening is a treatment that requires an interdisciplinary team approach.
- The physician must present an accurate diagnosis and communicate to the therapist who communicates their progress and findings back.
- Together with the patient, outcome goals are set.
- Other team members may include psychologist or occupational therapist.
- Open communication lines among the physician, patient, and physical and/or occupational therapist creates an important feedback loop.
Patient & family education
- “Back school” may be efficacious for both treatment and prevention.
- Encouraging patients to take an active role in their treatment often requires a change in previously held beliefs.
- Functional Capacity Examination (FCE)
- ROM may be quantified by goniometry.
- Core strength is more difficult to quantify. Surface electromyography is being explored to reduce subjectivity.8
Measurement of patient outcomes
- Outcome measurement in spinal disorders includes:
- pain measures such as visual analogue scores (VAS), or picture diagrams.
- functional measures such as Oswetsry scores, ShortForm (SF)-36, SF-12, or EuroQol.
- return to work or sport outcome scores.
- rate of re-injury.
Translation into practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills
- Core strengthening has become popular in recent exercise programs; many patients will ask for demonstration and training during a physician office visit. It is helpful to be aware of the various techniques that are essential to any rehabilitation exercise program.
- Early identification of core muscle weakness may prevent further functional deficits and injury to the spine.
- A recent meta-analysis found that core stability exercises were more effective than general exercise at reducing pain and improving function in patients with chronic LBP in the short term.9
- The physician should collaborate with therapists trained to employ these techniques.
4. CUTTING EDGE/EMERGING AND UNIQUE CONCEPTS AND PRACTICE
Cutting edge concepts and practice
- Core strengthening is constantly evolving with new exercises and techniques such as plyometrics and “muscle confusion.”
- New pain relieving interventions such as image guided injections serve as adjuncts to advance the rehabilitation and exercise program.
- One study10 found Pilates activates transversus abdominis and obliques and other researchers11 found efficacy to reduce spine pain.
- Yoga was found to be effective in reducing spinal pain.12
- Surface electromyographic analysis has been used to assess muscle activation in core stabilization exercises.13
5. GAPS IN THE EVIDENCE-BASED KNOWLEDGE
Gaps in the evidence-based knowledge
- There is still a lack of randomized, controlled studies proving the efficacy of core strengthening.
- Such studies could also further quantify the amount and intensity of exercise required for various diagnostic groups.
- Rantanen J, Hurme M, Falck B, et al. The lumbar multifidus muscle five years after surgery for a lumbar intervertebral disc herniation. Spine.l 1993;(5):568-74.
- Jarvik JG, Hollingworth W, Heagerty PJ, Haynor DR, Boyko EJ, Deyo RA. Three-year incidence of low back pain in an initially asymptomatic cohort: clinical and imaging risk factors. Spine. 2005;30(13):1541-8.
- Cady LD, Bischoff DP, O’Connell ER, Thomas PC, Allan JH. Strength and fitness and subsequent back injuries in firefighters. J Occup Med. 1979;21(4):269-72.
- Choi BK, Verbeek JH, Tam WW, Jiang JY. Exercises for prevention of recurrences of low-back pain. Cochrane Database Syst Rev. 2010; Issue 1. Art. No.: CD006555. DOI: 10. 1002/14651858. CD006555. Pub2.
- Freeman MD, Woodham MA, Woodham AW. The role of the lumbar multifidus in chronic low back pain: a review. Phys Med Rehabil. 2010;2(2):142-6, 168 (quiz). Review in PubMed PMID: 20193941.
- van den Hoogen HJ, Koes BW, van Eijk JT, Bouter LM, Devillé W. On the course of low back pain in general practice: a one year follow up study. Ann Rheum Dis. 1998; 57(1):13-9.
- Hayden J, van Tulder MW, Malmivaara A, Koes BW. Exercise therapy for treatment of non-specific low back pain. Cochrane Database of Systematic Reviews 2005, Issue 3.
- Ng JK, Richardson CA, Jull GA. Electromyographic amplitude and frequency changes in the iliocostalis lumborum and multifidus muscles during a trunk holding test. Phys Ther. 1997;77(9):954-61.
- YJ, Xu GH, Chen PJ. A meta-analysis of core stability exercise versus general exercise for chronic low back pain. PLoS One. 2012;7 (12):e52082
- Endleman I, Critchley DJ. Transversus abdominis and obliquus internus activity during pilates exercises: measurement with ultrasound scanning. Arch Phys Med Rehabil. 2008; 89(11):2205-12.
- Donzelli S, Di Domenica E, Cova AM, Galletti R, Giunta N. Two different techniques in the rehabilitation treatment of low back pain: a randomized controlled trial. Eura Medicophys. 2006;42(3):205-10.
- Sorosky S, Stilp S, Akuthota V. Yoga and pilates in the management of low back pain. Curr Rev Musculoskel Med.
- 2008;1(1):39-47. PubMed PMID: 19468897;
- Youdas JW, Boor MM, Darfler AL, Koenig MK, Mills KM, Hollman JH. Surface electromyographic analysis of core trunk and hip muscles during selected rehabilitation exercises in the side-bridge to neutral spine position. Sports Health. 2014 Sep;6(5):416-21
Original Version of the Topic:
Andrew Sherman, MD. Core Strengthening. Publication Date: 2011/11/10.
Ari Greis, MD
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