Core Strengthening

Disease/ Disorder

Definition

1. 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.
2. Strengthening increases intra-abdominal pressure acting as a natural corset protecting the spine. The goal is to prevent or reduce spine-generated pain.

Etiology

1. Weak core strength correlates with spinal injuries, yet causation remains unclear.
2. Rantanen¹ found multifidus weakness in persistently symptomatic patients up to 5 years after lumbar surgery.
3. Etiology is multifactorial. In up to 85% of all cases of low back pain, the mechanism of pain is the pain is poorly understood and is classified of non-specific i.e. unknown origin.²

Epidemiology including risk factors and primary prevention

1. Three-year prevalence of back pain is estimated to be 67%.³
2. Lifetime prevalence of back pain may approach 98%.³
3. A key contributor to the burden is the high recurrence rate: approximately one-half of patients experience a recurrence of LBP within 1 year after recovering from a previous episode.⁴
4. Important risk factors of back pain³
   • depression
   • poor socioeconomic status
   • jobs with manual lifting/repetitive strain
   • smoking
   • age
5. Cady’s study on firefighters with back pain reported that those who were more physically fit missed less work.⁵
6. A Cochrane review reported that post-treatment exercise programs prevent back pain recurrence. ⁶

Patho-anatomy/physiology

1. Dysfunction of the multifidus, transversus abdominis, and erector spinae muscles in neutral lumbar range of motion (ROM) is associated with LBP.⁷
2. 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.
3. Some studies have shown no single muscle is key to achieving lumbar spine stability and based on this, recommendations have been made for rehabilitation programs to involve the entire spinal musculature.²
4. Cardiorespiratory exercise programs have showed no effect in reducing chronic low back pain².

Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time)

1. Many spinal injuries respond to core stabilization, particularly in patients with a relatively unstable or flexible spine/segment.
2. Spinal pain may be axial, referred to the extremities (radiculopathy), or both.
3. Most acute spinal pain related to strains/sprains and disc related pathology improves dramatically within 2 to 4 weeks.
4. As many as 35% have pain after 12 weeks (subacute) and 10% have pain after 1 year (chronic).⁸ Additionally, 75% have at least one relapse within one year if no rehabilitation was performed.⁶

Specific secondary or associated conditions and complications

1. Assessment of systemic symptoms to rule out other pathology or benign non-spinal conditions is essential.
2. Spinal instability related to congenital and/or acquired spondylolisthesis may cause spinal cord or nerve root compression and subsequent neurological injuries.
3. Normal neurological examination ensures that there is no progressive neurological motor or sensory loss.

Essentials of Assessment

History

1. Pain assessment includes
   • onset
   • location
   • duration
   • character
   • intensity
   • exacerbating or remitting movements (may help direct treatment)
2. Red flags include fevers, chills, and weight loss
3. Neurologic considerations: weakness, numbness, bladder or bowel dysfunction, impaired balance

Physical examination

1. Consists of complete neurologic examination including reflex examination, manual muscle and sensory testing.
2. Assess alignment, posture, biomechanics and asymmetries of the lumbosacral spine and pelvis.
3. Palpation often localizes the pain to the vertebral body, facet joint, sacroiliac joints, iliolumbar ligaments, or lumbar paraspinals.
4. ROM localizes areas of tightness in the lumbar, pelvic, and lower extremity muscles and confirms any positional bias.
5. Manual strength testing of the core musculature identifies reflexively weak or inhibited muscles.
6. Exam findings can guide the exercise program, including determining if core strengthening will be useful.

Functional assessment

1. 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.
2. Chronic spinal pain can adversely affect vocational and avocational activities, cause depression, and result in reduced social interaction.

Laboratory studies

1. 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.

Imaging

1. 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.
2. 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.
3. Computerized tomography (CT) may show bony pathology in greater detail than MRI; myelography is useful if MRI is contraindicated.
4. Bone scan can reveal inflammation, infection, metastasis or fracture.
5. All radiographic abnormalities must be correlated to the clinical examination.

Supplemental assessment tools

1. Electrodiagnostic studies may improve accuracy when numbness or weakness are present or when complaints are not verified by physical exam or imaging.
2. 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

1. Many studies have found improved outcomes in both acute and chronic lumbar pain with exercise therapy.⁹
2. Consistent with current evidence, our results indicate that there is significantly lower chronic low back pain with intervention groups using an exercise intervention compared to other treatments².

Environmental

1. Spinal pain can compromise a person’s dignity and social status, with treatment implications decreasing compliance, particularly with active treatments.
2. Core stabilization can encourage a return to an “active” state and allow patients to take control over their treatment and recovery.
3. 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.

Professional Issues

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.

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.”
• This position is midway between lumbar flexion and extension¹⁰.
• 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.
• Since altered neuromuscular control is a predisposing factor in lower back pain, abdominal hollowing and abdominal bracing exercises should be started to improve neuromuscular control of local stabilizers. Diaphragmatic breathing exercises can also be introduced to improve core stability by generating a co-contraction of pelvic floor muscles and transverse abdominus ¹⁰.
• 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 or Swiss 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.
• It appears that a multifaceted program that incorporates strength, endurance, balance/posture, and neuromuscular control of the core and lower extremity are needed to reduce injury rates.¹¹
•  A successful program should begin with neuromuscular control of local stabilizers, followed by stabilization exercises to promote co-contraction of local and global stabilizers, and then progresses to dynamic functional activities. ¹²

At different disease stages

1. 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.
2. 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.
3. 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.
4. Pre-terminal care: patients with pain due to metastasis or fracture can sometimes benefit from gentle isometric exercises that improve function.

Coordination of care

1. Core strengthening is a treatment that requires an interdisciplinary team approach.
2. The physician must present an accurate diagnosis and communicate to the therapist who communicates their progress and findings back.
3. Together with the patient, outcome goals are set.
4. Other team members may include psychologist or occupational therapist.
5. Open communication lines among the physician, patient, and physical and/or occupational therapist creates an important feedback loop.

Patient & family education

1. “Back school” may be efficacious for both treatment and prevention.
2. Encouraging patients to take an active role in their treatment often requires a change in previously held beliefs.

Emerging/unique Interventions

Impairment-Based Measurement

1. Functional Capacity Examination (FCE)
2. ROM may be quantified by goniometry.
3. Core strength is more difficult to quantify. Surface electromyography is being explored to reduce subjectivity.¹³
4. Functional Movement Screen (FMS).¹⁴

Measurement of patient outcomes

1. Outcome measurement in spinal disorders includes:
   1. pain measures such as visual analogue scores (VAS), or picture diagrams.
   2. functional measures such as Oswetsry scores, ShortForm (SF)-36, SF-12, or EuroQol.
   3. return to work or sport outcome scores.
   4. rate of re-injury.

Translation into practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills

1. 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.
2. Early identification of core muscle weakness may prevent further functional deficits and injury to the spine.
3. 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.¹⁵
4. The physician should collaborate with therapists trained to employ these techniques.

Cutting Edge/ Emerging and Unique Concepts and Practice

1. Core strengthening is constantly evolving with new exercises and techniques such as plyometrics and “muscle confusion.”
2. Study was performed to find which exercises elicit the greatest activation from the core muscles by using surface EMG of 6 trunk muscles (rectus abdominus, external oblique, lumbar erector and thoracic erector spinae, and the deltoids and gluteal muscles)¹⁶
   • The activation of the core muscles was greatest when the deltoids or the gluteal muscles were activated¹⁶
3. New pain relieving interventions such as image guided injections serve as adjuncts to advance the rehabilitation and exercise program.
4. Core strengthening has been shown to decrease symptomatic patellofemoral syndrome (cite)
   • Hip and core strengthening together may result in earlier resolution of pain than strengthening the knee muscles alone^17,18

Emerging/unique interventions

1. One study¹⁹ found Pilates activates transversus abdominis and obliques and other researchers²⁰ found efficacy to reduce spine pain.
2. Pilates exercises have recruited multiple muscles of the core²¹
   • Can be used for neuromuscular re-education and restoring muscle balance²² in the elderly population who develop decreased trunk muscle strength and muscle balance due to age-related musculoskeletal changes (ex. Osteoporosis and sarcopenia)
   • Pilates is beneficial as it is easily modifiable and focuses on quality of the movement rather than quantity of repetitions²²
3. Yoga was found to be effective in reducing spinal pain.²³
   • Yoga has shown improvements in core strengthening and balance
4. Surface electromyographic analysis has been used to assess muscle activation in core stabilization exercises.²⁴

Gaps in the Evidence- Based Knowledge

1. There is still a lack of randomized, controlled studies proving the efficacy of core strengthening.
2. Such studies could also further quantify the amount and intensity of exercise required for various diagnostic groups.
3. There is a lack of studies that have published a standardized core strengthening program (amount of time, specific exercises, how often to perform)
4. Studies that evaluate core strengthening have a small sample size
5. Need more studies to validate clinical measures of core stability with tests such as the unilateral bridge endurance test²⁵
6. The long-term effect of home based versus supervised core strengthening programs also needs to be explored further²⁶ especially after the Coronavirus Pandemic of 2020 which closed all physical therapy and rehab centers nationwide

References

1. 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.
2. Searle A, Spink M, Ho A, Chuter V. Exercise interventions for the treatment of chronic low back pain: a systematic review and meta-analysis of randomised controlled trials. Clin Rehabil. 2015 Dec;29(12):1155-67. doi: 10.1177/0269215515570379. Epub 2015 Feb 13. PMID: 25681408.
3. 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.
4. Steffens D, Maher CG, Pereira LS, Stevens ML, Oliveira VC, Chapple M, Teixeira-Salmela LF, Hancock MJ. Prevention of Low Back Pain: A Systematic Review and Meta-analysis. JAMA Intern
5. 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.
6. 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.
7. 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.
8. 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.
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.
10. Akuthota V, Nadler SF. Core strengthening. Arch Phys Med Rehabil. 2004;85(3)(suppl 1):S86-S92
11. Hubscher M, Zech A, Pfeifer K. Neuromuscular training for sports injury prevention: a systematic review.Med Sci Sports Exerc.2010; 42:413-421
12. Akhuthota V, ferreiro A, Moore T. Core stability exercise principles. Curr Sports Med Rep. 2008;7 (1): 39-44
13. 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.
14. Cook G, Burton L, Hoogenboom B. Pre-participation screening: the use of fundamental movements as an assessment of function. Part 1. N Am J Sports Phys Ther. 2006; 1(2):62-72
15. 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
16. Gottschall J, Mills J, Hasting B. Integration Core Exercises Elicit Greater Muscle Activation Than Isolation Exercise . Journal of strength and conditioning research:March 2013-Volume 27- Issue 3 p 590-596
17. Patrick C et al. Postural Stability and Kinetic Change in Subjects with Patellofemoral pain after a Nine Week Hip and Core Strengthening Intervention. Int J Sports Phys Ther.2017 June, 12 (3): 314-323
18. Ferber R et al. Strengthening of the Hip and Core Versus Knee Muscles for the Treatment of Patellofemoral Pain: A Multicenter randomized controlled trial. Journal of Athletic training, 2015, 50(4):366-377
19. 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.
20. 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.
21. Panhan AC, Gonҫalves M, Eltz GD. Core muscle activation during pilates exercises on the Wunda chair. J Bodyw Mov Ther.2021 Jan; 25:165-169.
22. Smith K, Smith E. ATC/R Integrating Pilates-based Core Strengthening Into Older Adults Fitness Program, Topics in Geriatric Rehabilitation: January 2005-volume 21-issue1- p57-67
23. 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;
24. 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
25. Butowicz CM, Ebaugh DD, Noehren B, Silfies SP. VALIDATION OF TWO CLINICAL MEASURES OF CORE STABILITY. Int J Sports Phys Ther. 2016 Feb;11(1):15-23. PMID: 26900496; PMCID: PMC4739044.
26. Chuter VH, de Jonge XAKJ, Thompson BM et al. The efficacy of a supervised and a home-based core strengthening programme in adults with poor core stability: a three-arm randomized controlled trial. British Journal of Sports Medicine 2015; 49: 395-399

Original Version of the Topic

Andrew Sherman, MD. Core Strengthening. Publication Date: 11/102011.

Previous Revision(s) of the Topic

Ari Greis, MD. Core Strengthening. Publication Date: 5/5/2016.

Author Disclosures

Sol Abreu-Sosa, MD
Nothing to Disclose

Obada Obaisi, MD
Nothing to Disclose

Alethea Appavu, DO
Nothing to Disclose