Authors: Xian-Guo Meng, MD Shou-Wei Yue, MD
Aerobic Exercise
Affiliations: From the Department of Physical Medicine & Rehabilitation, QiLu Hospital, Shandong University, Jinan, P.R. China (X-GM, S-WY); and Department of Rehabilitation Medicine, Shandong Medical College, Jinan, P.R. China (X-GM).
Correspondence: All correspondence and requests for reprints should be addressed to: Xian-Guo Meng, MD, Department of Physical Medicine & Rehabilitation, QiLu Hospital, Shandong University, Jinan 250012, P.R. China; and Department of Rehabilitation Medicine, Shandong Medical College, 5460, South-Second Ring Road, Jinan 250002, P.R. China.
ORIGINAL RESEARCH ARTICLE
Efficacy of Aerobic Exercise for Treatment of Chronic Low Back Pain A Meta-Analysis ABSTRACT Meng X-G, Yue S-W: Efficacy of aerobic exercise for treatment of chronic low back pain: a meta-analysis. Am J Phys Med Rehabil 2 0 1 5 ;9 4 :3 5 8 -3 6 5 .
Objective:
A meta-analysis of relevant cohort studies was performed to in
vestigate the efficacy of aerobic exercise for the treatment of patients with chronic
Disclosures: Funded by A Project of Shandong Province Higher Educational Science and Technology Program (No. J10LF87). Financial disclosure statements have been obtained, and no conflicts of interest have been reported by the authors or by any individuals in control of the content of this article.
low back pain (CLBP).
Method:
A range of electronic databases were searched : M EDLIN E (19 6 6 -2 0 1 3 ),
the Cochrane Library Database (issue 12, 2013), EMBASE (1 9 8 0 -2 0 1 3 ), C IN AH L (1 9 8 2 -2 0 1 3 ), Web of Science ( 1 9 4 5 -2 0 1 3 ), and the Chinese Bio medical Database (1 9 8 2 -2 0 1 3 ), without language restrictions. The Roland-Morris Disability Questionnaire, the Oswestry Disability Questionnaire, the McGill Pain Questionnaire, visual analog scale, and heart rate, sit-and-reach test, and maximum oxygen consumption were used to evaluate the efficacy of aerobic exercise. Meta
Editor’s Note:
analysis was performed with the use of the STATA statistical software. The stan
Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www.ajpmr.com).
dardized mean difference (SMD) with its corresponding 9 5 % confidence interval (Cl) was calculated. Eight clinical cohort studies with a total of 3 1 0 C LB P patients were included in the meta-analysis.
Results:
The results of this meta-analysis indicated that C L B P patients
exhibited positive decreases in scores on the Roland-Morris Disability Question
0894-9115/15/9405-0358
American Journal of Physical Medicine & Rehabilitation Copyright © 2014 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/PHM.0000000000000188
naire (SMD, 0 .4 4 ; 9 5 % Cl, 0 .2 0 -0 .6 8 ; P < 0 .0 0 1 ), Oswestry Disability Questionnaire (SMD, 1.03; 9 5 % Cl, 0 .6 7 -1 .3 9 ; P < 0 .00 1), Hospital Anxiety and Depression Scale (SMD, 1.35; 9 5 % Cl, 0 .3 4 -2 .3 7 ; P = 0 .0 0 9 ), and McGill Pain Questionnaire (SMD, 0 .3 2 ; 9 5 % Cl, 0 .0 7 -0 .5 6 ; P = 0 .0 1 1) after aerobic exercise. It was also observed that aerobic exercise could markedly reduce the visual analog scale score for pain of C L B P patients (SMD, 0 .7 5 ; 9 5 % Cl, 0 .4 8 -1 .0 2 ; P < 0 .00 1). Nevertheless, this study’s findings showed that aerobic exercise had no effects on heart rate, sit-and-reach test, and maximum oxygen consumption of C L B P patients (all P > 0.05).
Conclusion:
The current meta-analysis provides reliable evidence that aerobic
exercise could effectively diminish pain intensity and improve the physical and psychologic functioning of C L B P patients. Thus, aerobic exercise may be a good choice in the treatment for CLBP. Key Words:
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Aerobic Exercise, Chronic Low Back Pain, Meta-Analysis
Am. J. Phys. Med. Rehabil. . Vol. 94, No. 5, May 2015
^ ^ h r o n ic low back pain (CLBP), generally re ferred to pain that has persisted for 3 mos or longer, is the second most common cause of disability in adults.1 The number of adults who experience back pain at some point in their lifetime is considerable, and the proportion of CLBP is much larger than that in the past.2 In recent years, disability caused by CLBP has increased steadily in all industrialized countries.3 It is well known that the development of CLBP is associated with a variety of risk factors, such as age, educational degree, obesity, and psychosocial factors including stress, anxiety, and depression.4 Because CLBP has posed enormous economic bur den on individuals, families, communities, and gov ernments because of its high prevalence and recurrence, it is extremely important to find available methods for the treatment of CLBP.1A wide range of different intervention methods, including surgery, drug therapy, and physical interventions, has been introduced for the treatment of CLBP.5Among them, aerobic exercise, the most commonly recommended intervention by guidelines and most widely used type of conservative treatment, has been demonstrated to be effective in the therapy for patients with CLBP.6 Aerobic exercise is defined as a form of physical exercise with relatively low intensity that predomi nately depends on the aerobic energy-generating process,7 consisting of various types of exercise, such as walking, running, treadmill, cycling, and calis thenics, which may provide many general health benefits, including causing weight loss; increasing aerobic capacity; decreasing insulin resistance, lipids, and systolic blood pressure; as well as decreas ing inflammation.8 Recently, aerobic exercises have gained much attention, and the benefits of aer obic exercises have been well accepted in many types of disorders, namely, hypertension, asthma, and CLBP.910 In general, the goal of the treatment of CLBP is to relieve pain, enhance mobility, prevent both physical and mental disability, and, thus, im prove life quality and physical functions.11 Many preclinical and clinical trials have proven that aerobic exercise is safe and effective in the treatment of CLBP, particularly in diminishing pain and increasing aer obic capacity, which may significantly affect clinical outcome of CLBP patients.12,13 There is evidence showing that aerobic exercise therapy, particularly in its high-intensity form, would not only reduce pain, disability, and psychologic strain in patients with CLBP but also act on most body systems, which might be effective in improving clinical symp toms.10,14 However, it has been argued that the addition of aerobic exercise treatment did not enhance www.ajpmr.com
either short- or long-term improvement of pain and disability in patients with CLBP.11,13,15 Given the conflicting evidence on this issue, a meta-analysis of all available cohort studies was conducted to investigate the efficacy of aerobic exercise for the treatment of CLBP patients. METHODS Publication Search
A range of electronic databases were searched: MEDLINE (1966-2013), the Cochrane Library Data base (issue 12,2013), EMBASE (1980-2013), CINAHL (1982-2013), Web of Science (1945-2013), and the Chinese Biomedical Database (1982-2013), without language restrictions. The following keywords and MeSH terms were used in conjunction with a highly sensitive search strategy: [“core strengthening exercise” or “core stability strength exercise” or “core stability exercises” or “aerobic exercise” or “core stabilization exercise” or “aerobic training” or “aerobic training exercise”] and [“low back pain” or “LBP” or “low back ache” or “chronic low back pain” or “recurrent low back pain” or “CLBP”]. A manual search was also conducted to find other potential articles based on references identified in the indi vidual articles. The following criteria were used for the eligi bility of included studies: (1) the study design must be a clinical cohort study that focused on the effi cacy of aerobic exercise for the treatment of CLBP patients; (2) all patients must have met the diag nostic criteria for CLBP; and (3) the study must provide sufficient information about the criteria for evaluating the efficacy of aerobic exercise. Articles that did not meet this study’s inclusion criteria were excluded. The most recent or the largest sample size publication was included when the authors published several studies using the same subjects. The Roland-Morris Disability Questionnaire, the Oswestry Disability Questionnaire, the McGill Pain Questionnaire, visual analog scale, and heart rate, sitand-reach test, maximum oxygen consumption were used to evaluate the efficacy of aerobic exercise. Data Extraction and Methodologic Assessment
Data were systematically extracted by two au thors from each included study by using a stan dardized form. The form used for data extraction documented the most relevant items, including language of publication; publication year; the first author’s surname; geographical location; design of study; sample size; source of the subjects; source of Aerobic Exercise for Treatment of CLBP
359
FIGURE 1 Study selection procedure. Nine cohort studies were included in this meta-analysis.
samples; duration of an exercise session; overall duration of the intervention; exercise type, fre quency, and intensity; and others. All authors were also contacted by e-mail to establish missing details in the methods and results sections. Methodologic quality was evaluated separately by two observers (X.G. Meng and S.W. Yue) using the Newcastle-Ottawa Scale (NOS) criteria.16 The NOS criteria are scored according to three aspects: (1) subject selection, 0— 4; (2) comparability of subject, 0-2; and (3) clinical outcome, 0-3. Total
NOS scores range from 0 to 9, and a score of 7 or higher indicates good quality. In case of conflicting evaluations, disagreements were resolved through discussion between the authors. Statistical A nalysis
Meta-analysis was performed with the use of the STATA statistical software (version 12.0; Stata Corporation, College Station, TX). Standardized mean differences (SMDs) with their corresponding 95% confidence intervals (95% CIs) were calculated
Publication year
FIGURE 2
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Distribution of the number o f topic-related literatures in the electronic database during the last decade.
Am. J. Phys. Med. Rehabil. . Vol. 94, No. 5, May 2015
as estimates of relative risk for CLBP. The Z test was used to estimate the statistical significance of pooled SMDs. Heterogeneity among studies was estimated by the Cochran Q statistic and I2 tests.17 If the Q test shows P < 0.05 or the I2 test exhibits greater than 50%, which indicates significant het erogeneity, a random-effect model was conducted, or else a fixed-effects model was used. To evaluate the influence of single studies on the overall esti mate, a sensitivity analysis was performed. Funnel plots and Egger linear regression test were applied to investigate publication bias. 18
RESULTS Eligible Studies Initially, the highly sensitive search strategy identified 60 articles. The titles and abstracts of all ar ticles were reviewed, and 23 articles were excluded; full texts were also reviewed, and 26 articles were further excluded. Another two studies were also excluded be cause of lack of data integrity (Fig. 1). Finally, eight clinical cohort studies with a total of 310 CLBP patients met this study’s inclusion criteria for quantitative data analysis.9,11^15,19'20 Publication years of the eligible studies ranged from 1990 to 2013. Figure 2 shows the distribution of the number of topic-related literatures in the electronic database during the last decade. Overall, six studies were conducted among whites, and only three studies were conducted among Asians. Visual analog scale was used to evaluate the severity of pain in all included studies. NOS scores of all included studies were 5 or higher. The main characteristics of all eligible studies are listed in Table 1 and Supplementary SI; http://links.lww.com/PHM/A80.
Quantitative Data Synthesis The results of this meta-analysis indicated that CLBP patients exhibited positive decreases in scores on the Roland-Morris Disability Questionnaire (SMD, 0.44; 95% Cl, 0.20-0.68; P < 0.001), Oswestry Dis ability Questionnaire (SMD, 1.03; 95% Cl, 0.67-1.39; P < 0.001), Hospital Anxiety and Depression Scale (SMD, 1.35; 95% Cl, 0.34-2.37; P = 0.009), and McGill Pain Questionnaire (SMD, 0.32; 95% Cl, 0.07-0.56; P = 0.011) after aerobic exercise. It was also observed that aerobic exercise could markedly reduce the visual analog scale score for pain of CLBP patients (SMD, 0.75; 95% Cl, 0.48-1.02; P< 0.001). Nevertheless, this study’s findings showed that aerobic exercise had no effects on heart rate, sit-and-reach test, and maximum oxygen consumption of CLBP patients (all P > 0.05) (Fig. 3). Sensitivity analyses for positive results suggested that no single study could influence the pooled estimates (Fig. 4 and Supplementary S2; www.ajpmr.com
Aerobic Exercise for Treatment of CLBP
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http://links.lww.com/PHM/A81). Funnel plots demon strated evidence of existing obvious asymmetry (Fig. 5). The Egger test also did not display strong statistical evidence for publication bias (all P > 0.05).
DISCUSSION In the present meta-analysis, the efficacy of aer obic exercise for the treatm ent of CLBP patients was evaluated. The findings of this study showed that CLBP patients presented a significant reduction in scores in the Roland-Morris Disability Questionnaire, Oswestry Disability Questionnaire, Hospital Anxiety and De pression Scale, and McGill Pain Questionnaire after aerobic exercise, indicating that aerobic exercise may have great benefits for the physical and psychologic functioning of CLBP patients. Although aerobic exer cise is one of the most commonly used treatment for
patients with chronic CLBP, the exact mechanism by which aerobic exercise reduces psychologic distress is still not fully understood. It was hypothesized that aerobic exercise may reduce resting beta-endorphin levels, which have been suspect to be correlated to depression, and contribute to improved mood.21 Moreover, this study’s results reveal that aerobic ex ercise is effective in the reduction of disability in pa tients with CLBP. A reasonable explanation may be that both disappearance of fear-avoidance beliefs and self-efficacy of exercise therapy may be marked factors to disability improvement in patients with chronic CLBP. Pain-related fear and depression have been con sidered to significantly influence disability in chronic CLBP patients owing to their fearing chronic pain.22 A nother im p o rtan t finding in this m eta analysis is that aerobic exercise may be helpful for
RMDQ score
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Murtezani A (2011)
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Koldas Dogan S -a (2008)
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0
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Heterogeneity test [P = 0.00%, P = 0.993) Z test (Z = 1.92, P = 0.055) -1 .3 6
FIGURE 3
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Meng and Yue
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0.42 (-0 .0 1 ,0 .8 6 )
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Forest plots for the efficacy o f aerobic exercise for treatment o f patients with CLBP. SRT indicates shuttle run test.
Am. J. Phys. Med. Rehabil. . Vol. 94, No. 5, May 2015
RMDQ score I Lower Cl Limit
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ODQ score
I Upper Cl Limit
I Lower Cl Limit
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| Upper Cl Limit I Lower Cl Limit
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O Estimate
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VAS score I Lower Cl Limit Murtezani A (2011) Chan CW (2011)
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|----------------------------------- p _____________________ I |----------------------------------- -e_____________________ I
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| - -— ................................ q
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|----------------------------------p ---------------------------------- 1
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O Estimate
|.....................p .................... |
Chatzitheodorou D (2007)
— — .......... — p ................................. |
Kell R T -a (2009)
Mannion A F -b (2001)
I Lower Cl Limit
I Upper Cl Limit
,|
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.........................................p............................... - .......
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|
........................................p................................... |— ...........- ....................... q | ..............
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|-............................ ........ p
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|.......................................
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........I
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Turner J A -c (1990) --------— ............................ ........................................^ 0.00
0.07
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O Estimate
0.32
0.56
V02 peak I Upper Cl Limit
Chan CW (2011)
I Lower Cl Limit
O Estimate
I Upper Cl Limit
Chan CW (2011)
Kell R T -a (2009)
Kell R T-b (2009)
Koldas Dogan S -a (2008) -0.3 6
FIGURE 4
-0.15
Sensitivity analysis of the summary odds ratio coefficients on the efficacy of aerobic exercise for treatment of patients with CLBP. SRT indicates shuttle run test.
diminishing pain intensity in CLBP patients. It is supposed that the chronic CLBP patients with highest depression and anxiety may experience the most pain.23 It has been demonstrated that aerobic www.ajpmr.com
exercise may be critical in chronic CLBP in several aspects13’19. First, when presenting a sufficient load for the achievement of training effect, aerobic ex ercise can minimize spinal loading at the lowest Aerobic Exercise for Treatment of CLBP
363
RMDQ score
ODQ score
Heart rate
VAS score
MGPQ score
SRT score
FI G URE 5 Funnel plot ofpublication biases on the efficacy ofaerobic exercise for treatment ofpatients with CLBP.
SRT indicates shuttle run test. possible load.24 Second, aerobic exercise functions significantly in enhancing the oxidative capacity of human skeletal muscles and promoting the con trol and coordination of neuromotor.25 Furthermore, by improving endurance and strength and preventing fatigue, aerobic exercise can prevent improper body mechanics causing by fatiguing muscles and thereby reduce low back pain and injury.26 Koldas Dogan et al.11 have demonstrated that aerobic exercise was effective in diminishing pain, disability, and psychologic de pression and thus increasing aerobic capacity in CLBP patients. To a great extent, the results of this study are consistent with previous studies implicating that aerobic exercise may contribute to the improvement of chronic CLBP,10 suggesting that aerobic exercise may of great value in the treatment of CLBP patients.
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The current meta-analysis has several limita tions that should be acknowledged. First, this study’s results lacked sufficient statistical power to assess the roles of aerobic exercise in the treatment of CLBP. Second, because meta-analysis is a retro spective study that may lead to subject selection bias, the reliability of this study’s results may have been thus affected. Third, this meta-analysis failed to obtain original data from the included studies, which limited the further evaluation of the poten tial effects of aerobic exercise for the treatment of CLBP patients. A fourth potential limitation stems from several of the results, which are constrained by small numbers and wide standard deviations, thereby limiting confidence in drawing conclu sions. These limitations notwithstanding, this is
Am. J. Phys. Med. Rehabil. . Vol. 94, No. 5, May 2015
the first meta-analysis focusing on the efficacy of aerobic exercise for treatment of CLBP. Further more, a highly sensitive literature search of elec tronic databases was performed, a manual search of the reference lists from the relevant articles was also conducted to find other potential articles, and the selection process of eligible articles was based on strict inclusion and exclusion criteria. In conclusion, the current meta-analysis pro vided reliable evidence that aerobic exercise could effectively diminish pain intensity and improve the physical and psychologic functioning of CLBP pa tients. Thus, aerobic exercise may a good choice in the treatment for CLBP. However, because of the limitations acknowledged above, further studies with larger sample sizes must be conducted to provide a more representative statistical analysis precisely. REFERENCES
1. Johannes CB, Le TK, Zhou X, et al: The prevalence of chronic pain in United States adults: Results of an Internet-based survey. J Pain 2010;11:1230-9 2. Hoy D, March L, Brooks P, et al: Measuring the global burden of low back pain. Best Pract Res Clin Rheumatol 2010;24:155-65 3. Freburger JK, Holmes GM, Agans RP, et al: The rising prevalence of chronic low back pain. Arch Intern Med 2009;169:251-8 4. Hoy D, Brooks P, Blyth F, et al: The epidemiology of low back pain. Best Pract Res Clin Rheumatol 2010; 24:769-81 5. van Middelkoop M, Rubinstein SM, Kuijpers T, et al: A systematic review on the effectiveness of physical and rehabilitation interventions for chronic non-specific low back pain. Eur Spine J 2011;20:19-39 6. van Middelkoop M, Rubinstein SM, Verhagen AP, et al: Exercise therapy for chronic nonspecific low-back pain. Best Pract Res Clin Rheumatol 2010:24:193-204 7. Schreuder L, Peters G, Nijhuis-van der Sanden R, et al: Aerobic exercise in children with oxidative phosphor ylation defects. Neurol Int 2010;2:e4 8. Knochel C, Oertel-Knochel V, O’Dwyer L, et al: Cog nitive and behavioural effects of physical exercise in psychiatric patients. Prog Neurobiol 2012;96:46-68 9. Barker KL, Dawes H, Hansford P, et al: Perceived and measured levels of exertion of patients with chronic back pain exercising in a hydrotherapy pool. Arch Phys Med Rehabil 2003;84:1319-23 10. Chatzitheodorou D, Kabitsis C, Malliou P, et al: A pilot study of the effects of high-intensity aerobic exercise versus passive interventions on pain, dis ability, psychological strain, and serum cortisol concentrations in people with chronic low back pain. Phys Ther 2007;87:304-12 11. Koldas Dogan S, Sonel Tur B, Kurtais Y, et al: Comparison of three different approaches in the www.ajpmr.com
treatment of chronic low back pain. Clin Rheumatol 2008;27:873-81 12. Tritilanunt T, Wajanavisit W: The efficacy of an aer obic exercise and health education program for treatment of chronic low back pain. J Med Assoc Thai 2001;84(suppl 2):S528-33 13. Chan CW, Mok NW, Yeung EW: Aerobic exercise training in addition to conventional physiotherapy for chronic low back pain: A randomized controlled trial. Arch Phys Med Rehabil 2011;92:1681-5 14. Kell RT, Asmundson GJ: A comparison of two forms of periodized exercise rehabilitation programs in the management of chronic nonspecific low-back pain. J Strength Cond Res 2009;23:513-23 15. Mannion AF, Muntener M, Taimela S, et al: Compari son of three active therapies for chronic low back pain: Results of a randomized clinical trial with one-year follow-up. Rheumatology (Oxford) 2001;40:772-8 16. Stang A: Critical evaluation of the Newcastle-Ottawa Scale for the assessment of the quality of nonrandomized studies in meta-analyses. Eur J Epidemiol 2010;25:603-5 17. Zintzaras E, Ioannidis JP: HEGESMA: Genome search meta-analysis and heterogeneity testing. Bioinformatics 2005;21:3672-3 18. Peters JL, Sutton AJ, Jones DR, et al: Comparison of two methods to detect publication bias in meta analysis. JAMA 2006;295:676-80 19. Murtezani A, Hundozi H, Orovcanec N, et al: A comparison of high intensity aerobic exercise and passive modalities for the treatment of workers with chronic low back pain: A randomized, controlled trial. Eur J Phys Rehabil Med 2011;47:359—66 20. Turner JA, Clancy S, McQuade KJ, et al: Effectiveness of behavioral therapy for chronic low back pain: A com ponent analysis. J Consult Clin Psychol 1990;58:573-9 21. Hurwitz EL, Morgenstern H, Chiao C: Effects of recreational physical activity and back exercises on low back pain and psychological distress: Findings from the UCLA Low Back Pain Study. Am J Public Health 2005;95:1817-24 22. Vlaeyen JW, Linton SJ: Fear-avoidance and its con sequences in chronic musculoskeletal pain: A state of the art. Pain 2000;85:317-32 23. Thomas EN, Pers YM, Mercier G, et al: The importance of fear, beliefs, catastrophizing and kinesiophobia in chronic low back pain rehabilitation. Ann Phys Rehabil Med 2010;53:3-14 24. Tawashy AE, Eng JJ, Krassioukov AV, et al: Aerobic exercise during early rehabilitation for cervical spinal cord injury. Phys Ther 2010;90:427-37 25. Konopka AR, Douglass MD, Kaminsky LA, et al: Molecular adaptations to aerobic exercise training in skeletal muscle of older women. J Gerontol A Biol Sci Med Sci 2010;65:1201-7 26. Voet NB, van der Kooi EL, Riphagen II, et al: Strength training and aerobic exercise training for muscle disease. Cochrane Database Syst Rev 2010;20:CD003907 Aerobic Exercise for Treatment of C LB P
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Aerobic Exercise
Affiliations: From the Department of Physical Medicine & Rehabilitation, QiLu Hospital, Shandong University, Jinan, P.R. China (X-GM, S-WY); and Department of Rehabilitation Medicine, Shandong Medical College, Jinan, P.R. China (X-GM).
Correspondence: All correspondence and requests for reprints should be addressed to: Xian-Guo Meng, MD, Department of Physical Medicine & Rehabilitation, QiLu Hospital, Shandong University, Jinan 250012, P.R. China; and Department of Rehabilitation Medicine, Shandong Medical College, 5460, South-Second Ring Road, Jinan 250002, P.R. China.
ORIGINAL RESEARCH ARTICLE
Efficacy of Aerobic Exercise for Treatment of Chronic Low Back Pain A Meta-Analysis ABSTRACT Meng X-G, Yue S-W: Efficacy of aerobic exercise for treatment of chronic low back pain: a meta-analysis. Am J Phys Med Rehabil 2 0 1 5 ;9 4 :3 5 8 -3 6 5 .
Objective:
A meta-analysis of relevant cohort studies was performed to in
vestigate the efficacy of aerobic exercise for the treatment of patients with chronic
Disclosures: Funded by A Project of Shandong Province Higher Educational Science and Technology Program (No. J10LF87). Financial disclosure statements have been obtained, and no conflicts of interest have been reported by the authors or by any individuals in control of the content of this article.
low back pain (CLBP).
Method:
A range of electronic databases were searched : M EDLIN E (19 6 6 -2 0 1 3 ),
the Cochrane Library Database (issue 12, 2013), EMBASE (1 9 8 0 -2 0 1 3 ), C IN AH L (1 9 8 2 -2 0 1 3 ), Web of Science ( 1 9 4 5 -2 0 1 3 ), and the Chinese Bio medical Database (1 9 8 2 -2 0 1 3 ), without language restrictions. The Roland-Morris Disability Questionnaire, the Oswestry Disability Questionnaire, the McGill Pain Questionnaire, visual analog scale, and heart rate, sit-and-reach test, and maximum oxygen consumption were used to evaluate the efficacy of aerobic exercise. Meta
Editor’s Note:
analysis was performed with the use of the STATA statistical software. The stan
Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www.ajpmr.com).
dardized mean difference (SMD) with its corresponding 9 5 % confidence interval (Cl) was calculated. Eight clinical cohort studies with a total of 3 1 0 C LB P patients were included in the meta-analysis.
Results:
The results of this meta-analysis indicated that C L B P patients
exhibited positive decreases in scores on the Roland-Morris Disability Question
0894-9115/15/9405-0358
American Journal of Physical Medicine & Rehabilitation Copyright © 2014 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/PHM.0000000000000188
naire (SMD, 0 .4 4 ; 9 5 % Cl, 0 .2 0 -0 .6 8 ; P < 0 .0 0 1 ), Oswestry Disability Questionnaire (SMD, 1.03; 9 5 % Cl, 0 .6 7 -1 .3 9 ; P < 0 .00 1), Hospital Anxiety and Depression Scale (SMD, 1.35; 9 5 % Cl, 0 .3 4 -2 .3 7 ; P = 0 .0 0 9 ), and McGill Pain Questionnaire (SMD, 0 .3 2 ; 9 5 % Cl, 0 .0 7 -0 .5 6 ; P = 0 .0 1 1) after aerobic exercise. It was also observed that aerobic exercise could markedly reduce the visual analog scale score for pain of C L B P patients (SMD, 0 .7 5 ; 9 5 % Cl, 0 .4 8 -1 .0 2 ; P < 0 .00 1). Nevertheless, this study’s findings showed that aerobic exercise had no effects on heart rate, sit-and-reach test, and maximum oxygen consumption of C L B P patients (all P > 0.05).
Conclusion:
The current meta-analysis provides reliable evidence that aerobic
exercise could effectively diminish pain intensity and improve the physical and psychologic functioning of C L B P patients. Thus, aerobic exercise may be a good choice in the treatment for CLBP. Key Words:
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Aerobic Exercise, Chronic Low Back Pain, Meta-Analysis
Am. J. Phys. Med. Rehabil. . Vol. 94, No. 5, May 2015
^ ^ h r o n ic low back pain (CLBP), generally re ferred to pain that has persisted for 3 mos or longer, is the second most common cause of disability in adults.1 The number of adults who experience back pain at some point in their lifetime is considerable, and the proportion of CLBP is much larger than that in the past.2 In recent years, disability caused by CLBP has increased steadily in all industrialized countries.3 It is well known that the development of CLBP is associated with a variety of risk factors, such as age, educational degree, obesity, and psychosocial factors including stress, anxiety, and depression.4 Because CLBP has posed enormous economic bur den on individuals, families, communities, and gov ernments because of its high prevalence and recurrence, it is extremely important to find available methods for the treatment of CLBP.1A wide range of different intervention methods, including surgery, drug therapy, and physical interventions, has been introduced for the treatment of CLBP.5Among them, aerobic exercise, the most commonly recommended intervention by guidelines and most widely used type of conservative treatment, has been demonstrated to be effective in the therapy for patients with CLBP.6 Aerobic exercise is defined as a form of physical exercise with relatively low intensity that predomi nately depends on the aerobic energy-generating process,7 consisting of various types of exercise, such as walking, running, treadmill, cycling, and calis thenics, which may provide many general health benefits, including causing weight loss; increasing aerobic capacity; decreasing insulin resistance, lipids, and systolic blood pressure; as well as decreas ing inflammation.8 Recently, aerobic exercises have gained much attention, and the benefits of aer obic exercises have been well accepted in many types of disorders, namely, hypertension, asthma, and CLBP.910 In general, the goal of the treatment of CLBP is to relieve pain, enhance mobility, prevent both physical and mental disability, and, thus, im prove life quality and physical functions.11 Many preclinical and clinical trials have proven that aerobic exercise is safe and effective in the treatment of CLBP, particularly in diminishing pain and increasing aer obic capacity, which may significantly affect clinical outcome of CLBP patients.12,13 There is evidence showing that aerobic exercise therapy, particularly in its high-intensity form, would not only reduce pain, disability, and psychologic strain in patients with CLBP but also act on most body systems, which might be effective in improving clinical symp toms.10,14 However, it has been argued that the addition of aerobic exercise treatment did not enhance www.ajpmr.com
either short- or long-term improvement of pain and disability in patients with CLBP.11,13,15 Given the conflicting evidence on this issue, a meta-analysis of all available cohort studies was conducted to investigate the efficacy of aerobic exercise for the treatment of CLBP patients. METHODS Publication Search
A range of electronic databases were searched: MEDLINE (1966-2013), the Cochrane Library Data base (issue 12,2013), EMBASE (1980-2013), CINAHL (1982-2013), Web of Science (1945-2013), and the Chinese Biomedical Database (1982-2013), without language restrictions. The following keywords and MeSH terms were used in conjunction with a highly sensitive search strategy: [“core strengthening exercise” or “core stability strength exercise” or “core stability exercises” or “aerobic exercise” or “core stabilization exercise” or “aerobic training” or “aerobic training exercise”] and [“low back pain” or “LBP” or “low back ache” or “chronic low back pain” or “recurrent low back pain” or “CLBP”]. A manual search was also conducted to find other potential articles based on references identified in the indi vidual articles. The following criteria were used for the eligi bility of included studies: (1) the study design must be a clinical cohort study that focused on the effi cacy of aerobic exercise for the treatment of CLBP patients; (2) all patients must have met the diag nostic criteria for CLBP; and (3) the study must provide sufficient information about the criteria for evaluating the efficacy of aerobic exercise. Articles that did not meet this study’s inclusion criteria were excluded. The most recent or the largest sample size publication was included when the authors published several studies using the same subjects. The Roland-Morris Disability Questionnaire, the Oswestry Disability Questionnaire, the McGill Pain Questionnaire, visual analog scale, and heart rate, sitand-reach test, maximum oxygen consumption were used to evaluate the efficacy of aerobic exercise. Data Extraction and Methodologic Assessment
Data were systematically extracted by two au thors from each included study by using a stan dardized form. The form used for data extraction documented the most relevant items, including language of publication; publication year; the first author’s surname; geographical location; design of study; sample size; source of the subjects; source of Aerobic Exercise for Treatment of CLBP
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FIGURE 1 Study selection procedure. Nine cohort studies were included in this meta-analysis.
samples; duration of an exercise session; overall duration of the intervention; exercise type, fre quency, and intensity; and others. All authors were also contacted by e-mail to establish missing details in the methods and results sections. Methodologic quality was evaluated separately by two observers (X.G. Meng and S.W. Yue) using the Newcastle-Ottawa Scale (NOS) criteria.16 The NOS criteria are scored according to three aspects: (1) subject selection, 0— 4; (2) comparability of subject, 0-2; and (3) clinical outcome, 0-3. Total
NOS scores range from 0 to 9, and a score of 7 or higher indicates good quality. In case of conflicting evaluations, disagreements were resolved through discussion between the authors. Statistical A nalysis
Meta-analysis was performed with the use of the STATA statistical software (version 12.0; Stata Corporation, College Station, TX). Standardized mean differences (SMDs) with their corresponding 95% confidence intervals (95% CIs) were calculated
Publication year
FIGURE 2
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Distribution of the number o f topic-related literatures in the electronic database during the last decade.
Am. J. Phys. Med. Rehabil. . Vol. 94, No. 5, May 2015
as estimates of relative risk for CLBP. The Z test was used to estimate the statistical significance of pooled SMDs. Heterogeneity among studies was estimated by the Cochran Q statistic and I2 tests.17 If the Q test shows P < 0.05 or the I2 test exhibits greater than 50%, which indicates significant het erogeneity, a random-effect model was conducted, or else a fixed-effects model was used. To evaluate the influence of single studies on the overall esti mate, a sensitivity analysis was performed. Funnel plots and Egger linear regression test were applied to investigate publication bias. 18
RESULTS Eligible Studies Initially, the highly sensitive search strategy identified 60 articles. The titles and abstracts of all ar ticles were reviewed, and 23 articles were excluded; full texts were also reviewed, and 26 articles were further excluded. Another two studies were also excluded be cause of lack of data integrity (Fig. 1). Finally, eight clinical cohort studies with a total of 310 CLBP patients met this study’s inclusion criteria for quantitative data analysis.9,11^15,19'20 Publication years of the eligible studies ranged from 1990 to 2013. Figure 2 shows the distribution of the number of topic-related literatures in the electronic database during the last decade. Overall, six studies were conducted among whites, and only three studies were conducted among Asians. Visual analog scale was used to evaluate the severity of pain in all included studies. NOS scores of all included studies were 5 or higher. The main characteristics of all eligible studies are listed in Table 1 and Supplementary SI; http://links.lww.com/PHM/A80.
Quantitative Data Synthesis The results of this meta-analysis indicated that CLBP patients exhibited positive decreases in scores on the Roland-Morris Disability Questionnaire (SMD, 0.44; 95% Cl, 0.20-0.68; P < 0.001), Oswestry Dis ability Questionnaire (SMD, 1.03; 95% Cl, 0.67-1.39; P < 0.001), Hospital Anxiety and Depression Scale (SMD, 1.35; 95% Cl, 0.34-2.37; P = 0.009), and McGill Pain Questionnaire (SMD, 0.32; 95% Cl, 0.07-0.56; P = 0.011) after aerobic exercise. It was also observed that aerobic exercise could markedly reduce the visual analog scale score for pain of CLBP patients (SMD, 0.75; 95% Cl, 0.48-1.02; P< 0.001). Nevertheless, this study’s findings showed that aerobic exercise had no effects on heart rate, sit-and-reach test, and maximum oxygen consumption of CLBP patients (all P > 0.05) (Fig. 3). Sensitivity analyses for positive results suggested that no single study could influence the pooled estimates (Fig. 4 and Supplementary S2; www.ajpmr.com
Aerobic Exercise for Treatment of CLBP
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http://links.lww.com/PHM/A81). Funnel plots demon strated evidence of existing obvious asymmetry (Fig. 5). The Egger test also did not display strong statistical evidence for publication bias (all P > 0.05).
DISCUSSION In the present meta-analysis, the efficacy of aer obic exercise for the treatm ent of CLBP patients was evaluated. The findings of this study showed that CLBP patients presented a significant reduction in scores in the Roland-Morris Disability Questionnaire, Oswestry Disability Questionnaire, Hospital Anxiety and De pression Scale, and McGill Pain Questionnaire after aerobic exercise, indicating that aerobic exercise may have great benefits for the physical and psychologic functioning of CLBP patients. Although aerobic exer cise is one of the most commonly used treatment for
patients with chronic CLBP, the exact mechanism by which aerobic exercise reduces psychologic distress is still not fully understood. It was hypothesized that aerobic exercise may reduce resting beta-endorphin levels, which have been suspect to be correlated to depression, and contribute to improved mood.21 Moreover, this study’s results reveal that aerobic ex ercise is effective in the reduction of disability in pa tients with CLBP. A reasonable explanation may be that both disappearance of fear-avoidance beliefs and self-efficacy of exercise therapy may be marked factors to disability improvement in patients with chronic CLBP. Pain-related fear and depression have been con sidered to significantly influence disability in chronic CLBP patients owing to their fearing chronic pain.22 A nother im p o rtan t finding in this m eta analysis is that aerobic exercise may be helpful for
RMDQ score
ODQ score
In c lu d e d s tu d y
S M D (9 5 % C l) W e ig h t%
In c lu d e d s t u d y
S M D (9 5 % C l) W e ig h t%
In c lu d e d s t u d y
S M D (9 5 % C l) W e ig h t%
Heart rate
HADS score In c lu d e d s t u d y
0.95 (0.53.1.36)
Murtezani A (2011)
1.35 (0 .3 4.2 .37 )
Heterogeneity test (P = 68.4%. P = 0.075)
61.84
100.00
S M D (9 5 % C l) W e lg h t%
Kell R T -a (2009)
-0 .6 8 (-1 .6 3 . 0.28)
Barker KL (2003)
4.47 (3.44, 5.50) 1.04 (-2 .2 2 .4 .3 0 )
Heterogeneity test (P = 97.0%, P < 0.001)
33.39
33.22 100.00
Z test (Z = 0.63, P = 0.530)
Z test (Z = 2.62, P = 0.009)
R an do m effe c ts a n alysis
Random effe cts a n alysis
-5 .5
3.11
-3.11
S M D (9 5 % C l) W e ig h t%
j
Chan CW (2011) ■
1 8 2 (1.3 5, 2.29) 1.58 (0.93, 2.23)
6.26
0.40 (-0 .5 4 ,1 .3 3 )
4.54
Mannion A F -a (2 0 0 1 )
0.13 (-0 .2 6 , 0.52)
Mannion A F -b (2001)
0.16 (-0 .2 4 , 0.55)
0 .8 0 (0 .1 4 ,1 .4 6 )
6.19
0 .8 8 (0 .2 1 ,1 .5 5 )
6.15
Mannion A F -a (2 0 0 1 )
0.35 (-0 .0 5 , 0.74)
8.11
b
Koldas Dogan S -a (2008)
S M D (9 5 % C l) W e ig h t%
In c lu d e d s tu d y
7.59
Koldas Dogan S -b (2008)
Mannion A F -c (2 0 0 1 )
fT
0.56 (0 .1 6, 0.96)
8.07
0.45 (0.05, 0.84)
8.09
Tritilanunt T (2001)
1.82 (1 .2 6,2 .37 )
6.98
Turner J A -a (1990)
0.49 (0.20, 0.78)
8.82
Mannion A F -b (2 0 0 1 ) |
Mannion A F -c (2 0 0 1 )
Turner J A -b (1990)
^
Turner JA -c (1 9 9 0 ) Heterogeneity test [P = 79.7%, P< 0.001) Z test (Z = 5.43, P< 0.001)
:
o
0.60 (0 .3 1 ,0 .8 9 )
8.81
0.25 (-0 .0 3 , 0.54)
8.84
0.75 (0.48, 1.02)
100.00
—
R andom effe cts a n alysis 0
-0 .0 5 (-0 .4 4 . 0.34)
H
14.51
Turner J A -a (1990)
0.25 (-0 .0 3 , 0.54)
17.65
Turner J A -b (1990)
0.38 (0.09, 0.67)
17.60
-i■U-
Turner J A - c ( 1990)
Heterogeneity test (P = 66.7%, P = 0.006) Z test (Z = 2.54, P = 0.011) Random e ffe c ts a n alysis
-2 .3 7
5.5
MGPQ score
VAS score In c lu d e d s t u d y Murtezani A (2011)
0
6
17.56
0.32 (0.07, 0.56)
100.00
J 3.5
-3 .5
2.37
0.48 (0 .1 9, 0.77)
V 0 2 peak
SRT score In c lu d e d s tu d y
SMD (95% Cl) W eight%
In c lu d e d s t u d y
S M D (9 5 % C l) W e lg h t%
0.44 (-0 .1 3 ,1 .0 1 )
Heterogeneity test [P = 0.00%, P = 0.993) Z test (Z = 1.92, P = 0.055) -1 .3 6
FIGURE 3
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Meng and Yue
0
0.42 (-0 .0 1 ,0 .8 6 )
100.00
Heterogeneity test (P = 0.00%, P = 0.962)
^
0.27 (-0 .1 5 , 0.70)
100.00
Z test ( Z = 1.25, P = 0.210) 1.36
-0.9 22
0.922
Forest plots for the efficacy o f aerobic exercise for treatment o f patients with CLBP. SRT indicates shuttle run test.
Am. J. Phys. Med. Rehabil. . Vol. 94, No. 5, May 2015
RMDQ score I Lower Cl Limit
o Estimate
ODQ score
I Upper Cl Limit
I Lower Cl Limit
O Estimate
I Upper Cl Limit
Koldas Dogan S -a (2008) Murtezani A (2011)
Koldas Dogan S -b (2008)
Chatzitheodorou D (2007) Kell R T -a (2009) Mannion A F -a (2 0 0 1 )
Mannion A F-b (2 0 0 1 )
Mannion A F-c(2001)
Kell R T -b (2009)
0
0.68
0.81
-23.33-21.73
2.31
HADS score I Lower Cl Limit
o Estimate
8.04
Heart rate
| Upper Cl Limit I Lower Cl Limit
Murtezani A (2011)
O Estimate
I Upper Cl Limit
Kell R T -a (2009)
Kell R T -b (2009)
Chatzitheodorou D (2007)
Barker KL (2003)
VAS score I Lower Cl Limit Murtezani A (2011) Chan CW (2011)
O Estimate
MGPQ score
|----------------------------------- p _____________________ I |----------------------------------- -e_____________________ I
Koldas Dogan S -a (2008)
p ....................................... < .............................
Koldas Dogan S -b (2008)
| - -— ................................ q
Barker KL (2003)
Mannion A F -c (2001) TritilanuntT (2001)
I Upper Cl Limit
|----------------------------------p ---------------------------------- 1
Kell R T -b (2009)
Mannion A F -a (2 0 0 1 )
O Estimate
|.....................p .................... |
Chatzitheodorou D (2007)
— — .......... — p ................................. |
Kell R T -a (2009)
Mannion A F -b (2001)
I Lower Cl Limit
I Upper Cl Limit
,|
Mannion A F -a (2001)
.....................................--p......................
Mannion A F -b (2001)
.........................................p............................... - .......
......
|
........................................p................................... |— ...........- ....................... q | ..............
___ I
Mannion A F -c (2001)
|-............................ ........ p
.......
......................q ......................................^
|.......................................
-p...................
|
Turner JA -a (1990)
|— .......................................~ p ........................................
Turner J A -b (1990)
I................ .............................. >.............................................
— — — ................... q .......... - ....................... |
Turner JA -a (1990)
) ..........................................- p ......................
Turner J A -b (1990)
|--------------------------------------p --------------------------------------- 1
Turner J A -c (1990)
|-...................................— p ...............
0.42 0.48
0.75
........I
.........j 1.02 1.09
Turner J A -c (1990) --------— ............................ ........................................^ 0.00
0.07
SRT score I Lower Cl Limit
O Estimate
0.32
0.56
V02 peak I Upper Cl Limit
Chan CW (2011)
I Lower Cl Limit
O Estimate
I Upper Cl Limit
Chan CW (2011)
Kell R T -a (2009)
Kell R T-b (2009)
Koldas Dogan S -a (2008) -0.3 6
FIGURE 4
-0.15
Sensitivity analysis of the summary odds ratio coefficients on the efficacy of aerobic exercise for treatment of patients with CLBP. SRT indicates shuttle run test.
diminishing pain intensity in CLBP patients. It is supposed that the chronic CLBP patients with highest depression and anxiety may experience the most pain.23 It has been demonstrated that aerobic www.ajpmr.com
exercise may be critical in chronic CLBP in several aspects13’19. First, when presenting a sufficient load for the achievement of training effect, aerobic ex ercise can minimize spinal loading at the lowest Aerobic Exercise for Treatment of CLBP
363
RMDQ score
ODQ score
Heart rate
VAS score
MGPQ score
SRT score
FI G URE 5 Funnel plot ofpublication biases on the efficacy ofaerobic exercise for treatment ofpatients with CLBP.
SRT indicates shuttle run test. possible load.24 Second, aerobic exercise functions significantly in enhancing the oxidative capacity of human skeletal muscles and promoting the con trol and coordination of neuromotor.25 Furthermore, by improving endurance and strength and preventing fatigue, aerobic exercise can prevent improper body mechanics causing by fatiguing muscles and thereby reduce low back pain and injury.26 Koldas Dogan et al.11 have demonstrated that aerobic exercise was effective in diminishing pain, disability, and psychologic de pression and thus increasing aerobic capacity in CLBP patients. To a great extent, the results of this study are consistent with previous studies implicating that aerobic exercise may contribute to the improvement of chronic CLBP,10 suggesting that aerobic exercise may of great value in the treatment of CLBP patients.
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The current meta-analysis has several limita tions that should be acknowledged. First, this study’s results lacked sufficient statistical power to assess the roles of aerobic exercise in the treatment of CLBP. Second, because meta-analysis is a retro spective study that may lead to subject selection bias, the reliability of this study’s results may have been thus affected. Third, this meta-analysis failed to obtain original data from the included studies, which limited the further evaluation of the poten tial effects of aerobic exercise for the treatment of CLBP patients. A fourth potential limitation stems from several of the results, which are constrained by small numbers and wide standard deviations, thereby limiting confidence in drawing conclu sions. These limitations notwithstanding, this is
Am. J. Phys. Med. Rehabil. . Vol. 94, No. 5, May 2015
the first meta-analysis focusing on the efficacy of aerobic exercise for treatment of CLBP. Further more, a highly sensitive literature search of elec tronic databases was performed, a manual search of the reference lists from the relevant articles was also conducted to find other potential articles, and the selection process of eligible articles was based on strict inclusion and exclusion criteria. In conclusion, the current meta-analysis pro vided reliable evidence that aerobic exercise could effectively diminish pain intensity and improve the physical and psychologic functioning of CLBP pa tients. Thus, aerobic exercise may a good choice in the treatment for CLBP. However, because of the limitations acknowledged above, further studies with larger sample sizes must be conducted to provide a more representative statistical analysis precisely. REFERENCES
1. Johannes CB, Le TK, Zhou X, et al: The prevalence of chronic pain in United States adults: Results of an Internet-based survey. J Pain 2010;11:1230-9 2. Hoy D, March L, Brooks P, et al: Measuring the global burden of low back pain. Best Pract Res Clin Rheumatol 2010;24:155-65 3. Freburger JK, Holmes GM, Agans RP, et al: The rising prevalence of chronic low back pain. Arch Intern Med 2009;169:251-8 4. Hoy D, Brooks P, Blyth F, et al: The epidemiology of low back pain. Best Pract Res Clin Rheumatol 2010; 24:769-81 5. van Middelkoop M, Rubinstein SM, Kuijpers T, et al: A systematic review on the effectiveness of physical and rehabilitation interventions for chronic non-specific low back pain. Eur Spine J 2011;20:19-39 6. van Middelkoop M, Rubinstein SM, Verhagen AP, et al: Exercise therapy for chronic nonspecific low-back pain. Best Pract Res Clin Rheumatol 2010:24:193-204 7. Schreuder L, Peters G, Nijhuis-van der Sanden R, et al: Aerobic exercise in children with oxidative phosphor ylation defects. Neurol Int 2010;2:e4 8. Knochel C, Oertel-Knochel V, O’Dwyer L, et al: Cog nitive and behavioural effects of physical exercise in psychiatric patients. Prog Neurobiol 2012;96:46-68 9. Barker KL, Dawes H, Hansford P, et al: Perceived and measured levels of exertion of patients with chronic back pain exercising in a hydrotherapy pool. Arch Phys Med Rehabil 2003;84:1319-23 10. Chatzitheodorou D, Kabitsis C, Malliou P, et al: A pilot study of the effects of high-intensity aerobic exercise versus passive interventions on pain, dis ability, psychological strain, and serum cortisol concentrations in people with chronic low back pain. Phys Ther 2007;87:304-12 11. Koldas Dogan S, Sonel Tur B, Kurtais Y, et al: Comparison of three different approaches in the www.ajpmr.com
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