841
Journal of Back and Musculoskeletal Rehabilitation 28 (2015) 841–847 DOI 10.3233/BMR-150596 IOS Press
Effects of core stability exercises on multifidus muscles in healthy women and women with chronic low-back pain Irina Klizienea,∗ , Saule Sipavicieneb , Sarunas Klizasc and Daiva Imbrasieneb a
Department of Education Science, Kaunas University of Technology, Kaunas, Lithuania Department of Applied Biology and Rehabilitation, Lithuanian Sports University, Kaunas, Lithuania c Department of Health Psychology, Lithuanian University of Health Sciences, Kaunas, Lithuania b
Abstract. BACKGROUND: Chronic low-back pain (LBP) may be related to decreased lumbar multifidus muscle cross-sectional area (CSA). OBJECTIVE: In this study, core stabilization exercises were designed to enhance neuromuscular control and correct multifidus dysfunction. METHODS: The subjects were healthy women (n = 11) and women with chronic LBP (n = 17). Lumbar multifidus muscle CSAs were measured by ultrasonography. Tests were carried out before training exercises for lumbar stability, and again 4 months and 8 months after training. RESULTS: In women with LBP, the mean multifidus muscle CSA increased by 22% on the right side and 23% on the left side after 8 months of lumbar stabilization training, compared with baseline measurements. In healthy women, mean multifidus muscle CSA increased by 24% on the right side and 23% on the left side, compared with baseline values. CONCLUSIONS: A core stabilization exercise program significantly increased multifidus muscle CSAs in both healthy women and women with chronic LBP. Keywords: Lumbar stability, multifidus muscle, low-back pain
1. Introduction Low-back pain (LBP) is one of the most common disorders and represents a substantial economic burden to society [1]. Chronic LBP is defined as back pain lasting more than 12 weeks [2]. Most patients suffer from LBP for over a year, and only 25% recover fully, without disability [3]. Over 70% of adults are thought to suffer from chronic LBP at least once in their lifetime [4]. ∗ Corresponding author: Irina Kliziene, Department of Education Science, Kaunas University of Technology, A. Mickeviciaus str. 37, LT-44248 Kaunas, Lithuania. Tel.: +370 37 453511; Fax: +370 37 453511; E-mail: [email protected].
A precise pathoanatomical diagnosis is only possible in 15% of patients with LBP [5]. Several studies have demonstrated multifidus muscle atrophy and a reduction in cross-sectional area (CSA) [6–9]. Magnetic resonance imaging investigations demonstrated multifidus muscle atrophy in 80% of patients suffering from chronic LBP [6]. Furthermore, ultrasound imaging showed that multifidus muscle CSA was smaller on the side of the lumbar part of the spine where the pain was expressed, indicating that muscle atrophy was localized, rather than widespread [8]. Using ultrasound, Wallwork et al. showed that patients with LBP had a significantly smaller multifidus muscle CSA than healthy subjects [9], while Danneels et al. demonstrated similar results using computed tomography in patients with chronic LBP [10].
c 2015 – IOS Press and the authors. All rights reserved ISSN 1053-8127/15/$35.00
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I. Kliziene et al. / Effects of core stability exercises on multifidus muscles
The lumbar multifidus muscles are important stabilizers of the spine, and dysfunction of these muscles is associated with LBP [11]. Weakening of the lumbar multifidus muscles leads to impaired function of the spine during both dynamic movement and in the static position. Exercises for LBP have focused on lumbar stabilization to reinforce the multifidus muscles and reduce LBP [12,13]. However, a previous study found no significant reduction in pain intensity after a spinal stabilization exercise program [14]. There has been much discussion regarding the most effective technique for improving spine stability [15]. A link between local muscle dysfunction and LBP has been suggested, with the development of clinical instability associated with an excessive range of abnormal segmental movement without muscular control [16]. Stabilization exercises have therefore been designed to enhance the neuromuscular control system and correct the dysfunction [17]. This study aimed to evaluate the influence of specific core stability exercises on multifidus muscle CSA in healthy women and women with chronic LBP.
2. Methods 2.1. Study population Twenty-eight volunteers women (n = 28) were divided into an experimental group (EG; n = 17) and a control group (CG; n = 11). In EG were included women with LBP. The subjects had been suffering from LBP for at least 3 months. Exclusion criteria included patients with neurological symptoms, spinal damage, cancer, or infectious diseases that could lead to chronic LBP, and other diseases that could affect physical performance. The mean age of the EG subjects was 44.4 ± 5.9 years, their body weight was 68.1 ± 8.9 kg, and their height was 166.4 ± 2.8 cm. The CG included healthy women aged 44.2 ± 5.5 years, with a body weight of 63.3 ± 7.2 kg, and a height of 165.9 ± 2.8 cm. All subjects engaged in an 8-month exercise program of lumbar stability training. Each subject signed a written informed consent form in accordance with the principles outlined in the Declaration of Helsinki. Ethical approval was obtained from Kaunas Regional Biomedical Research Ethics Committee. 2.2. Study design The subjects were engaged in an 8-month exercise program for training lumbar stability (45 min, twice a
week). Multifidus CSA was measured three times in both groups: before the exercise training, 4 months after the training, and 8 months after the training. The ODI questionnaire and visual analog pain scale were applied in the EG. All assessments were conducted by the same investigator in the same place, to reduce measurement errors. 2.3. Testing and assessment of multifidus muscle CSA Ultrasound scanning of the muscles was carried out using a TITAN ultrasound system (SonoSite, USA). Multiple muscle CSAs (cm2 ) were measured in the Bscan mode. An HST/10-5 MHz 25 mm linear probe was used to image the surfaces of the muscles, organs and blood vessels, at a frequency of 10 MHz. During the study, subjects were posed face down in a relaxed, neutral head position, with their arms relaxed at their sides. A small pillow was placed under the stomach to reduce lordosis of the lumbar part of the spine. Ultrasound scanning of multiple muscles was performed in parallel on both sides of the spine in the region of the L4–L5 lumbar segments. The fourth lumbar vertebra (L4) was determined by palpation, starting from the wings of the hip bones towards the center line [18]. 2.4. Oswestry Disability Index questionnaire and visual analog pain scale The Oswestry Disability Index (ODI) questionnaire [19,20] was used to evaluate the influence of LBP intensity on the patient’s functional state in different life situations [21,22]. Pain intensity was evaluated using a visual analog pain scale with a range of 0 to 10 points, where 0 = no pain; 2 = mild pain; 4 = moderate pain; 6 = severe pain; 8 = very severe pain; and 10 = unbearable pain [23,24]. 2.5. Exercise program The subjects carried out the core stability exercise program for 45 min, twice a week, for 8 months. The program was divided into three categories: warm up, main part, and cool down, as described by Aluko et al. [25]. Participants in the EG and CG were required to perform eight repetitions of each exercise. At the start of each exercise, the examiner determined the subject’s lumbar neutral spine position and the subject was asked to hold this position throughout the exercise. The exercises were performed in a random sequence. Markers were placed on the floor to standardize the po-
I. Kliziene et al. / Effects of core stability exercises on multifidus muscles
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Spinal bridging. Lying on your back with knees bent and arms by your side (neutral position), flatten your spine into the floor and tighten your tummy muscles. Repeat 8 times.
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Leg kick. Lying on your back with knees bent and arms by your side (neutral position), slowly slide your leg straight and then bend it back to the start position. Repeat 8 times.
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B
C
D
Half roll down. Lying on your back with knees bent and arms by your side (neutral position), breath in, make pelvic muscles active, do not curve. Breath out, stretch arms forward while tensing bottom muscles, raise head (chin to chest) and rise up from the carpet with rounded back, rising one vertebra at a time (from neck to bottom).
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Roll down. Lie down, stretch arms above your head, lower your shoulders and do not curve the back. Breath in, make pelvic muscles active, do not curve Breath out, stretch arms forward while tensing bottom muscles, raise head (chin to chest) and rise up from the carpet with rounded back, rising one vertebra at a time (from neck to bottom).
Side balance. Lie on one side, put both legs slightly raised. perpendicular to the floor. Put head on one stretched arm, with the other arm bent and put behind the face, leaning on the floor. Keep waist stretched while tensing stomach and legs muscles, do not turn pelvis to the front. Breath in and stretch leg forward, then breath out and recover leg back. Repeat with the other leg. Fig. 1. Core stability exercise program [25].
sitions of the subject and the equipment. The exercises met suggested safety criteria, including avoiding active hip flexion with fixed feet positioning and pulling with the hands behind the head, and ensuring knee and hip flexion during all upper body exercises [25] (Fig. 1).
2.6. Statistical analysis The data were analyzed using descriptive and mathematical statistical methods. The normality of the data was analyzed using the Shapiro-Wilk test. Data were
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I. Kliziene et al. / Effects of core stability exercises on multifidus muscles Table 1 Effects of core stability exercises on lumbar multifidus muscle of cross-sectional area (cm2 )
Group Experimental Control
Baseline Right side Left side 6.57 ± 1.3 6.55 ± 1.4 6.98 ± 0.7∗ 7.04 ± 0.9∗
∗ P < 0.05 comparing experimental and the control groups; sides.
After 4 months Right side Left side 7.96 ± 0.9# 7.91 ± 1.1# 8.1 ± 1.2∗# 8.11 ± 0.9∗# #P
After 8 months Right side Left side 8.42 ± 0.6# 8.48 ± 0.7# 9.17 ± 0.8∗# 9.2 ± 0.7∗#
< 0.05 comparing the first and third measurements on the left and the right
analyzed by analysis of variance (ANOVA), and homogeneity of variances was tested using the Levene test. Differences between means were tested by the post hoc Bonferroni criterion. The level of significance was P < 0.05.
3. Results 3.1. Multifidus muscle CSA Data on multifidus muscle CSA in the EG and CG at baseline and 4 and 8 months after lumbar stabilization exercise program are shown in Table 1. Multifidus muscle CSA was significantly increased after stabilization training, compared with before training. Mean multifidus muscle CSA in the EG had increased significantly at 8 months by 22% on the right side and 23% on the left side, compared with baseline (P < 0.05). The mean multifidus muscle CSA also increased significantly in the CG, by 24% on the right side and 23% on the left side (P < 0.05). Prior to starting the the lumbar stabilization exercise program, the multifidus muscle CSA in the EG was significantly lower than that in the CG, by 6% on the right side and 7% on the left side (P < 0.05). After completing the lumbar stabilization exercise program, the multifidus muscle CSA in the EG remained significantly lower than in the CG, by 8% on both sides (P < 0.05) (Table 1). 3.2. Evaluation of ODI The mean ODI in the EG decreased by 46.7% after the exercise program, from 13.3 to 7.1% (P < 0.05) (Fig. 2). 3.3. Evaluation of LBP intensity The mean baseline pain intensity score in the EG was 3.8 ± 1.4 (Fig. 3). Pain intensity decreased (P < 0.05) in almost all (94.4%) subjects after the program, and no patients experienced an increase in pain intensity.
4. Discussion The results of this study demonstrated that a core stabilization exercise program could effectively reduce pain in patients with chronic LBP. This was in agreement with the results of other studies that showed pain reduction after 10 [26,27] or 12 weeks [28] in LBP patients who performed specific spinal stabilization exercises. Weakness of lumbar multifidus and abdominal muscles is an important risk factor for LBP [29–31]. Specific core stabilization exercise programs can restore the function of weakened muscles, and strengthen the spine and pelvic muscles in patients with chronic LBP, by reducing mechanical irritation and also reducing spasms in the low back region [27]. Strengthening of specific muscles is often associated with significantly reduced LBP, as well as decreased functional disability [32]. Freeman et al. suggested that the condition of the lumbar multifidus muscles was best demonstrated by magnetic resonance imaging; however, we used ultrasound imaging, as demonstrated in other studies [8,9]. Our results showed that the lumbar multifidus CSA was greater in healthy women than in women with chronic LBP. Similar results were found by Wallwork et al. Lumbar multifidus muscle dysfunction is the result of pain inhibition from the spine [11]. In addition to reducing LBP, it is also necessary to strenghten the multifidus muscles because of their important role in lumbar segmental stability [7], and atrophy of lumbar multifidus muscles may contribute to the high recurrence rate of chronic LBP [7,11]. In our study, lumbar multifidus CSA increased after 8 months of a specific core stabilization exercise program in both healthy women and women with chronic LBP. Previous studies also found that patients with LBP had significantly smaller multifidus CSAs at the lowest two vertebral levels than asymptomatic subjects [8,9]. Multifidus muscle atrophy can occur in highly active, elite athletes with LBP. We showed that specific retraining improved multifidus muscle CSA, concomitant with a decrease in pain. Hides et al. [12] found that the CSA of the multifidus muscles at the L5 verte-
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Fig. 2. The Oswestry Disability Index before and after lumbar stabilization exercise program. Significances to baseline ∗ P < 0.05.
Fig. 3. Low-back pain before and after lumbar stabilization exercise program. Significances to baseline ∗ P < 0.05.
bral level increased after stabilization training in seven cricketers with LBP, compared with 14 cricketers without LBP who did not receive rehabilitation. Classic trunk-strengthening exercises involve activation of the abdominal and paraspinal musculature at high levels of contraction. Such strengthening exercises differ from stability exercises, which are designed to stabilize muscles, initially by low-level isometric activation, followed by progressive integration into everyday activities [33]. The CSAs of the multifidus muscles in the EG and CG were measured before, and 4 and 8 months after stabilization training. The rationale behind this treatment concept is that the segmental stability of the lumbar spine is controlled by deep-lying muscles, such as the multifidus and transversus abdominis, which have an anatomical connection to the lum-
bar spine [34]. The relationship between anatomical structure and function has been described by Panjabi [35]: stability in a lumbar segment requires a coordinated interaction between the passive subsystem (osteoligamentous structures), the active subsystem (muscles), and the neural subsystem (central and peripheral nervous systems controlling the muscles). Hayden and colleagues performed a meta-analysis of exerciseintervention types and their effects on pain and disability, and concluded that supervised exercise therapy consisting of individually-designed programmes, including stretching or strengthening stabilization exercises, might improve pain reduction in patients with chronic non-specific LBP [32]. A significant improvement in transversus abdominis contractibility after a program of spine stabilization exercises concurs with the findings of Ferreira et al. [36]. In their study, 11
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patients undertook stabilization exercise therapy and a further 23 patients either performed general exercise or received spinal manipulation. Compared with the latter two groups, the stabilization group showed significantly greater changes in the ability to recruit the transversus abdominis, though the difference was largely accounted for by a worsening in the other groups, rather than a significant improvement in the stabilization group. This study confirmed that a core stabilization exercise program could effectively strengthen multifidus muscles and reduce pain in patients with chronic LBP. This suggests that such exercises promote a healthy lifestyle and may help to treat and prevent LBP.
5. Conclusions The core stabilization exercise program described in this study significantly increased multifidus muscle CSA in healthy women and women with chronic LBP.
Conflict of interest This manuscript has not been submitted or published elsewhere. This manuscript has been read and approved by all authors. Each author believes that the manuscript represents honest work. Each author has read and agreed to the terms of the IOS Press Author Copyright Agreement. There is no conflict of interest.
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França FR, Burke TN, Hanada ES, Marques AP. Segmental stabilization and muscular strengthening in chronic low back pain: A comparative study. Clinics (Sao Paulo). 2010; 65(10): 1013-1017. [32] Hayden JA, van Tulder MW, Malmivaara A, Koes BW. Exercise therapy for treatment of non-specific low back pain. Cochrane Database Syst Rev. 2005; (3): CD000335. [33] Norris CM. Back stability. Champaign: Human Kinetics, 2000. [34] Urquhart DM, Barker PJ, Hodges PW, Story IH, Briggs CA. Regional morphology of the transversus abdominis and obliquus internus and externus abdominis muscles. Clin Biomech. 2005; 20: 233-241. [35] Panjabi MM. The stabilizing system of the spine. Part II. Neutral zone and instability hypothesis. J Spinal Disord. 1992; 5: 390-397. [36] Ferreira PH, Ferreira ML, Maher CG, Refshauge K, Herbert RD, Hodges PW. Changes in recruitment of transversus abdominis correlate with disability in people with chronic low back pain. Br J Sports Med. 2010; 44: 1166-1172.
Journal of Back and Musculoskeletal Rehabilitation 28 (2015) 841–847 DOI 10.3233/BMR-150596 IOS Press
Effects of core stability exercises on multifidus muscles in healthy women and women with chronic low-back pain Irina Klizienea,∗ , Saule Sipavicieneb , Sarunas Klizasc and Daiva Imbrasieneb a
Department of Education Science, Kaunas University of Technology, Kaunas, Lithuania Department of Applied Biology and Rehabilitation, Lithuanian Sports University, Kaunas, Lithuania c Department of Health Psychology, Lithuanian University of Health Sciences, Kaunas, Lithuania b
Abstract. BACKGROUND: Chronic low-back pain (LBP) may be related to decreased lumbar multifidus muscle cross-sectional area (CSA). OBJECTIVE: In this study, core stabilization exercises were designed to enhance neuromuscular control and correct multifidus dysfunction. METHODS: The subjects were healthy women (n = 11) and women with chronic LBP (n = 17). Lumbar multifidus muscle CSAs were measured by ultrasonography. Tests were carried out before training exercises for lumbar stability, and again 4 months and 8 months after training. RESULTS: In women with LBP, the mean multifidus muscle CSA increased by 22% on the right side and 23% on the left side after 8 months of lumbar stabilization training, compared with baseline measurements. In healthy women, mean multifidus muscle CSA increased by 24% on the right side and 23% on the left side, compared with baseline values. CONCLUSIONS: A core stabilization exercise program significantly increased multifidus muscle CSAs in both healthy women and women with chronic LBP. Keywords: Lumbar stability, multifidus muscle, low-back pain
1. Introduction Low-back pain (LBP) is one of the most common disorders and represents a substantial economic burden to society [1]. Chronic LBP is defined as back pain lasting more than 12 weeks [2]. Most patients suffer from LBP for over a year, and only 25% recover fully, without disability [3]. Over 70% of adults are thought to suffer from chronic LBP at least once in their lifetime [4]. ∗ Corresponding author: Irina Kliziene, Department of Education Science, Kaunas University of Technology, A. Mickeviciaus str. 37, LT-44248 Kaunas, Lithuania. Tel.: +370 37 453511; Fax: +370 37 453511; E-mail: [email protected].
A precise pathoanatomical diagnosis is only possible in 15% of patients with LBP [5]. Several studies have demonstrated multifidus muscle atrophy and a reduction in cross-sectional area (CSA) [6–9]. Magnetic resonance imaging investigations demonstrated multifidus muscle atrophy in 80% of patients suffering from chronic LBP [6]. Furthermore, ultrasound imaging showed that multifidus muscle CSA was smaller on the side of the lumbar part of the spine where the pain was expressed, indicating that muscle atrophy was localized, rather than widespread [8]. Using ultrasound, Wallwork et al. showed that patients with LBP had a significantly smaller multifidus muscle CSA than healthy subjects [9], while Danneels et al. demonstrated similar results using computed tomography in patients with chronic LBP [10].
c 2015 – IOS Press and the authors. All rights reserved ISSN 1053-8127/15/$35.00
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I. Kliziene et al. / Effects of core stability exercises on multifidus muscles
The lumbar multifidus muscles are important stabilizers of the spine, and dysfunction of these muscles is associated with LBP [11]. Weakening of the lumbar multifidus muscles leads to impaired function of the spine during both dynamic movement and in the static position. Exercises for LBP have focused on lumbar stabilization to reinforce the multifidus muscles and reduce LBP [12,13]. However, a previous study found no significant reduction in pain intensity after a spinal stabilization exercise program [14]. There has been much discussion regarding the most effective technique for improving spine stability [15]. A link between local muscle dysfunction and LBP has been suggested, with the development of clinical instability associated with an excessive range of abnormal segmental movement without muscular control [16]. Stabilization exercises have therefore been designed to enhance the neuromuscular control system and correct the dysfunction [17]. This study aimed to evaluate the influence of specific core stability exercises on multifidus muscle CSA in healthy women and women with chronic LBP.
2. Methods 2.1. Study population Twenty-eight volunteers women (n = 28) were divided into an experimental group (EG; n = 17) and a control group (CG; n = 11). In EG were included women with LBP. The subjects had been suffering from LBP for at least 3 months. Exclusion criteria included patients with neurological symptoms, spinal damage, cancer, or infectious diseases that could lead to chronic LBP, and other diseases that could affect physical performance. The mean age of the EG subjects was 44.4 ± 5.9 years, their body weight was 68.1 ± 8.9 kg, and their height was 166.4 ± 2.8 cm. The CG included healthy women aged 44.2 ± 5.5 years, with a body weight of 63.3 ± 7.2 kg, and a height of 165.9 ± 2.8 cm. All subjects engaged in an 8-month exercise program of lumbar stability training. Each subject signed a written informed consent form in accordance with the principles outlined in the Declaration of Helsinki. Ethical approval was obtained from Kaunas Regional Biomedical Research Ethics Committee. 2.2. Study design The subjects were engaged in an 8-month exercise program for training lumbar stability (45 min, twice a
week). Multifidus CSA was measured three times in both groups: before the exercise training, 4 months after the training, and 8 months after the training. The ODI questionnaire and visual analog pain scale were applied in the EG. All assessments were conducted by the same investigator in the same place, to reduce measurement errors. 2.3. Testing and assessment of multifidus muscle CSA Ultrasound scanning of the muscles was carried out using a TITAN ultrasound system (SonoSite, USA). Multiple muscle CSAs (cm2 ) were measured in the Bscan mode. An HST/10-5 MHz 25 mm linear probe was used to image the surfaces of the muscles, organs and blood vessels, at a frequency of 10 MHz. During the study, subjects were posed face down in a relaxed, neutral head position, with their arms relaxed at their sides. A small pillow was placed under the stomach to reduce lordosis of the lumbar part of the spine. Ultrasound scanning of multiple muscles was performed in parallel on both sides of the spine in the region of the L4–L5 lumbar segments. The fourth lumbar vertebra (L4) was determined by palpation, starting from the wings of the hip bones towards the center line [18]. 2.4. Oswestry Disability Index questionnaire and visual analog pain scale The Oswestry Disability Index (ODI) questionnaire [19,20] was used to evaluate the influence of LBP intensity on the patient’s functional state in different life situations [21,22]. Pain intensity was evaluated using a visual analog pain scale with a range of 0 to 10 points, where 0 = no pain; 2 = mild pain; 4 = moderate pain; 6 = severe pain; 8 = very severe pain; and 10 = unbearable pain [23,24]. 2.5. Exercise program The subjects carried out the core stability exercise program for 45 min, twice a week, for 8 months. The program was divided into three categories: warm up, main part, and cool down, as described by Aluko et al. [25]. Participants in the EG and CG were required to perform eight repetitions of each exercise. At the start of each exercise, the examiner determined the subject’s lumbar neutral spine position and the subject was asked to hold this position throughout the exercise. The exercises were performed in a random sequence. Markers were placed on the floor to standardize the po-
I. Kliziene et al. / Effects of core stability exercises on multifidus muscles
A
B
Spinal bridging. Lying on your back with knees bent and arms by your side (neutral position), flatten your spine into the floor and tighten your tummy muscles. Repeat 8 times.
A
B
Leg kick. Lying on your back with knees bent and arms by your side (neutral position), slowly slide your leg straight and then bend it back to the start position. Repeat 8 times.
A
B
C
D
Half roll down. Lying on your back with knees bent and arms by your side (neutral position), breath in, make pelvic muscles active, do not curve. Breath out, stretch arms forward while tensing bottom muscles, raise head (chin to chest) and rise up from the carpet with rounded back, rising one vertebra at a time (from neck to bottom).
A
B
C
D
A
B
843
Roll down. Lie down, stretch arms above your head, lower your shoulders and do not curve the back. Breath in, make pelvic muscles active, do not curve Breath out, stretch arms forward while tensing bottom muscles, raise head (chin to chest) and rise up from the carpet with rounded back, rising one vertebra at a time (from neck to bottom).
Side balance. Lie on one side, put both legs slightly raised. perpendicular to the floor. Put head on one stretched arm, with the other arm bent and put behind the face, leaning on the floor. Keep waist stretched while tensing stomach and legs muscles, do not turn pelvis to the front. Breath in and stretch leg forward, then breath out and recover leg back. Repeat with the other leg. Fig. 1. Core stability exercise program [25].
sitions of the subject and the equipment. The exercises met suggested safety criteria, including avoiding active hip flexion with fixed feet positioning and pulling with the hands behind the head, and ensuring knee and hip flexion during all upper body exercises [25] (Fig. 1).
2.6. Statistical analysis The data were analyzed using descriptive and mathematical statistical methods. The normality of the data was analyzed using the Shapiro-Wilk test. Data were
844
I. Kliziene et al. / Effects of core stability exercises on multifidus muscles Table 1 Effects of core stability exercises on lumbar multifidus muscle of cross-sectional area (cm2 )
Group Experimental Control
Baseline Right side Left side 6.57 ± 1.3 6.55 ± 1.4 6.98 ± 0.7∗ 7.04 ± 0.9∗
∗ P < 0.05 comparing experimental and the control groups; sides.
After 4 months Right side Left side 7.96 ± 0.9# 7.91 ± 1.1# 8.1 ± 1.2∗# 8.11 ± 0.9∗# #P
After 8 months Right side Left side 8.42 ± 0.6# 8.48 ± 0.7# 9.17 ± 0.8∗# 9.2 ± 0.7∗#
< 0.05 comparing the first and third measurements on the left and the right
analyzed by analysis of variance (ANOVA), and homogeneity of variances was tested using the Levene test. Differences between means were tested by the post hoc Bonferroni criterion. The level of significance was P < 0.05.
3. Results 3.1. Multifidus muscle CSA Data on multifidus muscle CSA in the EG and CG at baseline and 4 and 8 months after lumbar stabilization exercise program are shown in Table 1. Multifidus muscle CSA was significantly increased after stabilization training, compared with before training. Mean multifidus muscle CSA in the EG had increased significantly at 8 months by 22% on the right side and 23% on the left side, compared with baseline (P < 0.05). The mean multifidus muscle CSA also increased significantly in the CG, by 24% on the right side and 23% on the left side (P < 0.05). Prior to starting the the lumbar stabilization exercise program, the multifidus muscle CSA in the EG was significantly lower than that in the CG, by 6% on the right side and 7% on the left side (P < 0.05). After completing the lumbar stabilization exercise program, the multifidus muscle CSA in the EG remained significantly lower than in the CG, by 8% on both sides (P < 0.05) (Table 1). 3.2. Evaluation of ODI The mean ODI in the EG decreased by 46.7% after the exercise program, from 13.3 to 7.1% (P < 0.05) (Fig. 2). 3.3. Evaluation of LBP intensity The mean baseline pain intensity score in the EG was 3.8 ± 1.4 (Fig. 3). Pain intensity decreased (P < 0.05) in almost all (94.4%) subjects after the program, and no patients experienced an increase in pain intensity.
4. Discussion The results of this study demonstrated that a core stabilization exercise program could effectively reduce pain in patients with chronic LBP. This was in agreement with the results of other studies that showed pain reduction after 10 [26,27] or 12 weeks [28] in LBP patients who performed specific spinal stabilization exercises. Weakness of lumbar multifidus and abdominal muscles is an important risk factor for LBP [29–31]. Specific core stabilization exercise programs can restore the function of weakened muscles, and strengthen the spine and pelvic muscles in patients with chronic LBP, by reducing mechanical irritation and also reducing spasms in the low back region [27]. Strengthening of specific muscles is often associated with significantly reduced LBP, as well as decreased functional disability [32]. Freeman et al. suggested that the condition of the lumbar multifidus muscles was best demonstrated by magnetic resonance imaging; however, we used ultrasound imaging, as demonstrated in other studies [8,9]. Our results showed that the lumbar multifidus CSA was greater in healthy women than in women with chronic LBP. Similar results were found by Wallwork et al. Lumbar multifidus muscle dysfunction is the result of pain inhibition from the spine [11]. In addition to reducing LBP, it is also necessary to strenghten the multifidus muscles because of their important role in lumbar segmental stability [7], and atrophy of lumbar multifidus muscles may contribute to the high recurrence rate of chronic LBP [7,11]. In our study, lumbar multifidus CSA increased after 8 months of a specific core stabilization exercise program in both healthy women and women with chronic LBP. Previous studies also found that patients with LBP had significantly smaller multifidus CSAs at the lowest two vertebral levels than asymptomatic subjects [8,9]. Multifidus muscle atrophy can occur in highly active, elite athletes with LBP. We showed that specific retraining improved multifidus muscle CSA, concomitant with a decrease in pain. Hides et al. [12] found that the CSA of the multifidus muscles at the L5 verte-
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Fig. 2. The Oswestry Disability Index before and after lumbar stabilization exercise program. Significances to baseline ∗ P < 0.05.
Fig. 3. Low-back pain before and after lumbar stabilization exercise program. Significances to baseline ∗ P < 0.05.
bral level increased after stabilization training in seven cricketers with LBP, compared with 14 cricketers without LBP who did not receive rehabilitation. Classic trunk-strengthening exercises involve activation of the abdominal and paraspinal musculature at high levels of contraction. Such strengthening exercises differ from stability exercises, which are designed to stabilize muscles, initially by low-level isometric activation, followed by progressive integration into everyday activities [33]. The CSAs of the multifidus muscles in the EG and CG were measured before, and 4 and 8 months after stabilization training. The rationale behind this treatment concept is that the segmental stability of the lumbar spine is controlled by deep-lying muscles, such as the multifidus and transversus abdominis, which have an anatomical connection to the lum-
bar spine [34]. The relationship between anatomical structure and function has been described by Panjabi [35]: stability in a lumbar segment requires a coordinated interaction between the passive subsystem (osteoligamentous structures), the active subsystem (muscles), and the neural subsystem (central and peripheral nervous systems controlling the muscles). Hayden and colleagues performed a meta-analysis of exerciseintervention types and their effects on pain and disability, and concluded that supervised exercise therapy consisting of individually-designed programmes, including stretching or strengthening stabilization exercises, might improve pain reduction in patients with chronic non-specific LBP [32]. A significant improvement in transversus abdominis contractibility after a program of spine stabilization exercises concurs with the findings of Ferreira et al. [36]. In their study, 11
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patients undertook stabilization exercise therapy and a further 23 patients either performed general exercise or received spinal manipulation. Compared with the latter two groups, the stabilization group showed significantly greater changes in the ability to recruit the transversus abdominis, though the difference was largely accounted for by a worsening in the other groups, rather than a significant improvement in the stabilization group. This study confirmed that a core stabilization exercise program could effectively strengthen multifidus muscles and reduce pain in patients with chronic LBP. This suggests that such exercises promote a healthy lifestyle and may help to treat and prevent LBP.
5. Conclusions The core stabilization exercise program described in this study significantly increased multifidus muscle CSA in healthy women and women with chronic LBP.
Conflict of interest This manuscript has not been submitted or published elsewhere. This manuscript has been read and approved by all authors. Each author believes that the manuscript represents honest work. Each author has read and agreed to the terms of the IOS Press Author Copyright Agreement. There is no conflict of interest.
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