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Journal of Back and Musculoskeletal Rehabilitation 28 (2015) 521–530 DOI 10.3233/BMR-140551 IOS Press
Effect of trunk muscles training using a star excursion balance test grid on strength, endurance and disability in persons with chronic low back pain G. Shankar Ganesha,∗, Deepak Chhabrab , Monalisa Pattnaika , Patitapaban Mohantya, Rishee Patela and Kumar Mrityunjayc a
SVNIRTAR, Olatpur, P.O. Bairoi, Cuttack Dt., Orissa, India Advanced Certificate Course in Manual Physical Therapy, JSPL, Raigarh, Chattisgarh, India c Nopany Institute of Health Sciences, Girish Park, Kolkata, India b
Abstract. BACKGROUND AND OBJECTIVES: Though core muscles strengthening using upper limbs in various positions and lower limbs in lying have been studied previously in patients with chronic low back pain (CLBP), no study has specifically looked in to the effects of a training program that requires prior motor planning in standing (functional position). The objective of this study was to evaluate the effectiveness of star excursion balance test (SEBT) grid training in improving the outcomes in patients with CLBP. MATERIALS AND METHOD: Sixty patients with mechanical CLBP who fulfilled our criteria were randomized in to two groups; experimental group received physical diagnostic specific interventions, core muscles strengthening and muscles training using the SEBT grid. The participants in control group received stationary cycling instead of SEBT grid training and the other interventions were uniform. The duration of study was 4 weeks. The dependent variables were analyzed using repeated measures 2 × 3 ANOVA. RESULTS: At the end of study, both the groups showed a significant reduction in disability and improvement in strength and endurance (p < 0.05). Post-hoc analysis showed that SEBT grid training was better than conventional exercises. Follow-up at 16 weeks revealed a statistically insignificant loss in strength and endurance in control group patients. This reduction was not associated with an increase in disability score. The experimental group patients continued showing improvement. CONCLUSION: The results of our study show that core muscles strengthening using a SEBT grid are more effective than conventional programs. We hypothesize SEBT training to have a significant role in skill learning. We recommend SEBT grid training to be incorporated in the treatment planning of persons with CLBP. Keywords: Low back pain, exercise, muscle strength, musculoskeletal manipulations, motor skills
1. Introduction
∗ Corresponding author: G. Shankar Ganesh, Department of Physiotherapy, SVNIRTAR, Olatpur, P.O. Bairoi, Cuttack Dt., Orissa, 754010, India. Tel.: +91 9437279869; E-mail: shankarpt@ rediffmail.com.
Chronic low back pain (CLBP) is defined as a persistent and disabling low back pain lasting more than 3 months [1]. CLBP is not related to any underlying pathologies like infection, neoplasm, or fracture [2]. Neurophysiologic studies have linked pain development in the lumbar spine to the disturbances in the
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mechanoreceptors and impairment of the superior proprioception centers [3]. It has been found that the coordination of low back muscles and postural stability are reduced in patients with CLBP [4,5]. Further, chronic pain is associated with reduced brain gray matter and impaired cognitive ability [6]. Several studies have also indicated abnormal cortical function in people with CLBP [7–11]. Recent evidence suggests that the management of CLBP should focus on supervised exercises and have indicated short-term pain relief from manual therapy approaches [12]. CLBP is a difficult condition to treat with variable results [13] and the expenditure associated with repeated treatment in these patients necessitates an effective treatment strategy. The Star Excursion Balance test (SEBT) [14] is used for dynamic balance assessment and is composed of controlled closed kinetic chain motion activities. A study by the 1st , 2nd and 6th authors [15] showed that patients with CLBP have inferior reach excursions on SEBT when compared to controls. The results were attributed to reduced core muscles strength and proprioceptive deficits in patients with CLBP and we hypothesized that working on SEBT grid would counteract that. Further, no study has specifically studied the effect of core muscles strengthening on a standing lower limb activity that requires prior motor planning. The objective of this study was to find the effectiveness of trunk muscle training using a SEBT grid in persons with CLBP. 2. Methods The study was a prospective trial. Participants who met the following inclusion criteria were recruited for the study: (1) back pain, lasting more than three months and radiating no further below knee, (2) normal neurological examination, (3) age 25–60 years, and (4) mechanical pain provoked with postures, movement and activities. Patients with the following criteria were excluded: (1) patients receiving another treatment apart from standard doses of NSAIDS, (2) pain aggravating in less than 3 minutes of standing, (3) any pathology or surgery at or around spine, pelvis, hip, knee and ankle, (4) acute exacerbation of CLBP, (5) pregnancy, (6) psychiatric disorder and (7) red flags to manual therapy. Sixty patients (36 males and 24 females) with mean age (39.7 ± 8.3) participated and completed the study. Informed consent was obtained from all the participants and the procedure was approved by the institute ethics committee.
Fig. 1. Pressure bio-feedback unit. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/BMR-140551)
2.1. Outcome measures The following dependant variables were assessed for: 2.1.1. Strength and endurance measurement by pressure-biofeedback unit (PBU) Strength and endurance of trunk extensors, transverse abdominis and abdominal obliques were measured by PBU (Chattanooga INC) (Fig. 1) [16]. The accuracy of PBU is described as ± 3 mm Hg and is considered a reliable and valid indicator of muscle function [17,18]. Three investigators with more than 15 years of experience in musculo-skeletal physiotherapy and blinded to the study measured all the outcome measures. The investigators attended a training session prior to the study, where they discussed the measurement procedure. All the data were collected before randomization in a private room with only the investigators present. One investigator gave commands to the participants and the second investigator ensured that contraction was not accompanied by breath hold, pelvic tilt, bracing or substitutionary co-contraction of the gluteus maximus and erector spinae muscles. The third investigator recorded the mean change in mm Hg pressure registered on the device. The participants were positioned as described below. The PBU was inflated to 70 mm of Hg. The participants were instructed to contract the specific muscles. The changes in the pressure reflect the strength of contraction of the muscles and number of repetitions reflects the endurance of the respective muscles. Readings were measured at the completion of a
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Table 1 Physical diagnosis and the criteria for diagnosis Physical diagnosis Lumbar Derangement Syndrome (Posterior) Criteria: Centralization of pain with repetitive extension & peripheralization with repetitive flexion. Flexion Dysfunction Criteria: Loss of trunk flexion with localized pain before achievement of full normal range of flexion. Spondylolisthesis Criteria: Radiograph showing forward shift of upper segments over the lower with or without lysis of pars interarticularis. Soft Disc Lesion Criteria: Lower back with radiating pain where leg pain is more than back pain. Pain aggravated with flexion of the trunk. Spondylosis Criteria: Limitation and pain in extension. Radiograph showing osteophytes and other degenerative changes. Non-Specific Criteria: The problems encountered do not lend itself to a true medical diagnosis. Although clinical presentation of a patient with this condition is fairly easy to recognize, the explanations given for the underlying pathology are controversial and contentious.
No. of patients Experimental Control Total 08 06 14 04
02
06
04
06
10
08
06
14
04
06
10
02
04
06
Fig. 2. Measurement of transverse abdominis muscle strength using PBU. (Colours are visible in the online version of the article; http:// dx.doi.org/10.3233/BMR-140551)
Fig. 3. Measurement of abdominal obliques and back extensors muscle strength using PBU. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/BMR-140551)
10-second contraction over three consecutive contractions, with one minute rest between contractions. The highest score amongst the three 10 second contractions was recorded as strength [18]. No feedback was given to the subjects during data collection [18,19]. Transversus Abdominis (TrA) was tested in prone position (Fig. 2). The inflated cell was placed beneath the abdomen at the level of the anterior superior iliac spine and the patient was instructed to gently and slowly draw the lower abdomen below the navel without moving the upper stomach, back or pelvis [18]. Abdominal Obliques (bilateral external and internal obliques) (Fig. 3) and back extensors (Erector Spinae and Multifidus) (Fig. 3) were tested in supine lying position. The inflated cell was placed at the level of the posterior superior iliac spine. To evaluate the abdomi-
nal obliques, participants were instructed to gently and slowly press the cell, as if to straighten the spine, and for back extensors, the instruction was to lift the weight off the cell like arching the spine, without moving the upper stomach, back or pelvis, while breathing in and out [20]. 2.1.2. Oswestry Disability Index (ODI) The ODI was used to measure patients’ functional disability. ODI is considered the ‘gold standard’ of low back functional outcome tools [21]. 2.2. Procedure The clinicians attended a training session prior to the study, where they discussed the assessment and in-
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G.S. Ganesh et al. / SEBT grid training in CLBP Table 2 Interventions and their indications Technique Exercises − Spinal Flexion − Spinal Extension − McKenzie Extension − Static Trunk Loading Lumbar mobilization (Maitland) − Central PA Vertebral Pressure − Unilateral PA Vertebral Pressure Traction − Supine − Prone Electrotherapy − IFT (4-pole) − TENS Stretching − Rectus Femoris − Piriformis
Indication − Increased lumbar lordosis, Flexion dysfunction − Reduced lumbar lordosis, Extension dysfunction − Posterior Lumbar Derangement Syndrome − Core muscle activation − Bilaterally disturbed symptoms/Hypomobility − Unilaterally disturbed symptoms/Hypomobility Radicular signs, unable to centralize symptoms or muscle spasm − If flexion is pain free, extension is painful − If extension is pain free, flexion is painful or if both flexion and extension are painful − Central back pain/muscle spasm − Pain radiating to Lower Limbs − Tightness as determined by Ely’s Test − Limited hip external rotation with hip in flexion, without any associated spasms Table 3 Dosage parameters
Exercise Extension − Trunk extension in prone − Bilateral lower limb extension in prone − Contralateral lower limb extension in prone − Extension in standing Flexion − Flexion in lying (knee to chest) − Toe touch in long sitting − Flexion in standing − Flexion in step standing McKenzie extension exercises − Prone lying − Repetitive extension in lying Static trunk loading Patient was instructed to lie supine and raise both legs to hip in 90◦ flexion with knees completely flexed and arms raised to 30◦ –40◦ while maintaining the abdominal hollowing and glutei contraction, while maintaining normal breathing. Maitland spinal mobilization − Posterior – anterior central and unilateral
Traction Supine/prone, as per indication Interferential therapy TENS
Stretching Rectus femoris Piriformis
tervention procedure. The participants were randomized in to two different groups by consecutive sampling. Two manipulative physiotherapists with post graduate training in manual therapy and more than 20 years of clinical experience assessed and performed the spinal mobilizations, stretching maneuvers and ap-
Dosage 10 sec hold and 3 repetitions in each position.
10 repetitions in each position
10 repetitions with few seconds hold
Rate: 2–3 oscillations per second Intensity: as tolerated by the patient Duration: 2–3 minutes/vertebra Traction was given statically with 1/2 of body weight as traction force for 10 minutes 15 minutes Pulse duration – 40 usec Frequency – 100 Hz Treatment duration – 20 min 6–10 repetitions of 6 second hold and 5 seconds rest
plied all the electro-therapeutic modalities. The assessment involved analysis of the subject’s pain provocative postures, movements, functional tasks and radiographs to arrive at a specific physical diagnosis and where the assessment was in-conclusive, a diagnosis of non-specific low back pain was given . The SEBT
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Table 4 Results of the study Variable Transversus Abdominis Strength (Figure-5) Transversus Abdominis Endurance (Figure-6) Abdominal Obliques Strength (Figure-7) Abdominal Obliques Endurance (Figure-8) Back Extensor Strength (Figure-9) Back Extensor Endurance (Figure-10) ODI (Figure-11)
Time (f value) 225.078 (p = 0.00) 376.017 (p = 0.00) 164.802 (p = 0.00) 236.478 (p = 0.00) 582.470 (p = 0.00) 222.983 (p = 0.00) 398.670 (p = 0.00)
Group (f value) 164.829 (p = 0.00) 129.538 (p = 0.00) 266.278 (p = 0.00) 237.636 (p = 0.00) 196.224 (p = 0.00) 371.541 (p = 0.00) 39.679 (p = 0.00)
Time X Group (f value) 200.56 (p = 0.00) 179.036 (p = 0.00) 122.104 (p = 0.00) 242.261 (p = 0.00) 392.058 (p = 0.00) 127.877 (p = 0.00) 5.164 (p = 0.01)
Fig. 4. Eight excursion directions for both feet.
grid training, cycling, static trunk loading and McKenzie extension exercises were supervised by a musculoskeletal physiotherapist with more than 12 years of clinical experience. Tables 1, 2 and 3 summarize the physical diagnoses, criterion for diagnosis, respective interventions and dosages prescribed to study participants. Group I (30 subjects, 11 females and 19 males. mean age 38.53 ± 8.30) received diagnosis specific interventions, core muscles strengthening and SEBT grid training. Group II (30 subjects, 13 females and 17 males. mean age 40.86 ± 8.55) received diagnosis specific interventions, core muscle strengthening and stationary cycling at their own pace for 15 minutes. All participants received the intervention for a period of five sessions per week for 4 weeks. The SEBT grid used for this study was constructed in the department using a protractor and 3-inch-wide black color adhesive tape. The grid consisted of eight lines (directions) laid on the floor extending at 45◦ increments from the center (Fig. 4). This exercise required subjects to do an abdominal drawing in maneuver (ADIM) and maintain balance on a single limb (stance leg) while trying to reach as far as possible with the most distal part of their reach foot and touch
as lightly as possible to ensure they are not using that leg for support. The subjects then returned to bilateral stance while maintaining balance. A verbal and visual demonstration of the testing procedure was given to each subject by one of the authors. All participants in the experimental group made 10 repetitions in each direction with a five to ten seconds rest period in between. Once all the sets with one foot were completed, the same procedure was repeated with stance on the other foot after 3 minutes of rest. The exercise was performed once daily, 5 times per week for 4 weeks. All the measurements were taken prior to the beginning of the intervention, and at 4th and 16th weeks. At the end of the program, all subjects were taught self stretching, core strengthening exercises and received individual instructions regarding maintenance of optimal posture and ergonomic advice. Participants were encouraged to follow these instructions, continue the exercises and avoid immobility. 2.3. Statistical analysis The data was analyzed with SPSS (Statistical Package for Social Sciences) 16.0 version. The dependent variables were analyzed using repeated measures 2 × 3
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Strength of Transversus Abdominis
mm of Hg
7
Experimental
Post1
6 5 4 3
0
Control
Experimental
Control
Fig. 7. Graph showing changes in abdominal obliques muscle strength before and after intervention and at follow-up. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/ BMR-140551)
Abdominal Obliques Endurance
Endurance of Transversus Abdominis Pre Post Post1
9
number of repetitions
number of repetitions
Pre Post
8
2 1
Fig. 5. Graph showing changes in Transverse abdominis muscle strength before and after intervention and at follow-up. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/ BMR-140551)
10 9 8 7 6 5 4 3 2 1 0
Abdominal Obliques Strength
9
Pre Post Post1
mm of Hg
10 9 8 7 6 5 4 3 2 1 0
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Pre
8
Post
7
Post1
6 5 4 3 2 1
Experimental
Control
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Control
Fig. 6. Graph showing changes in Transverse abdominis muscle endurance before and after intervention and at follow-up. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/ BMR-140551)
Fig. 8. Graph showing changes in abdominal obliques muscle endurance before and after intervention and at follow-up. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/ BMR-140551)
ANOVA. All pair wise post hoc comparison was done using a 0.05 level of significance.
group for all the outcome measures and this main effect achieved significant group X time interaction. Tukeys post-hoc analysis showed that experimental group was better than the control group in improving the outcomes. The control group showed statistically insignificant reduction in strength and endurance at follow-up, while the experimental group continued to improve. However, the ODI scores showed a further reduction at follow-up.
3. Results Sixty participants were enrolled for the study and there was no drop out of patients till follow-up. The mean duration of pain in the experimental group was 7.3 months and 6.8 months in the control group. A one-way ANOVA revealed that both the groups did not differ in baseline measures. Participants from both the groups admitted their inability to stick to their instructed home based self-exercise programs as per regime. The overall results (Table 4) (Figs 5–11) of the study showed that there was a main effect for the time and
4. Discussion This is the first study to present the results of the efficacy of SEBT grid training on CLBP. The results support the hypothesis that a 4-week SEBT grid training offers greater clinical benefits to CLBP patients than
G.S. Ganesh et al. / SEBT grid training in CLBP
mm of Hg
12
Back Extensor Strength
ODI
Pre
10
Post
8
Post1
6
Experimental
number of repetitions
20
Post1
15
0
Control
Fig. 9. Graph showing changes in back extensors muscle strength before and after intervention and at follow-up. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/BMR140551)
Back Extensor Endurance Pre
8
Post
6
Post1
4 2 0
Pre Post
5
2
10
25
10
4
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Experimental
Control
Fig. 10. Graph showing changes in back extensors muscle strength before and after intervention and at follow-up. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/BMR140551)
the conventional program. The significant improvements by SEBT subjects were maintained at the 16week follow-up, indicating that the SEBT grid training is associated with longer lasting reductions in disability. In addition, subjects felt working in the SEBT grid was more sportive due to its competitive nature. Exercise physiologists suggest that to improve muscle strength, a load that exceeds the metabolic capacity of the muscle must be applied. Studies have experimentally demonstrated that skeletal adaptations can occur in various skeletal muscle fibers types at four weeks, if the training intensity is sufficient [22, 23]. The American college of sports medicine guidelines [24] and Chromiak [25] stated that 8–12 repetitions of specific exercise once daily is sufficient to bring about muscle strength, when done five times a week. The participants were prescribed exercises tar-
Experimental
Control
Fig. 11. Graph showing changes in Oswestry disability index before and after intervention and at follow-up. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/BMR140551)
geting the core muscles with a dosage that satisfied the above criteria, leading to strength gains. Mobilization to spine influences pain relief through its mechanical and neuro-physiological mechanisms [26,27] and prior manual therapy to lumbar spine increases the activity of multifidus [28]. Lumbar extension training session of one per week has been found sufficient to improve strength [29] and improvement in strength is associated with decreased pain scores in CLBP [30]. Harman, 2009 [31] proposed that the use of electrophysiological agents in the treatment of CLBP has a positive effect if used as an adjunct to manual therapy and exercises. The superior strength gain in the SEBT grid training may be attributed to the multi-directional reaching along with the ADIM done by the participants. Carpenter et al. [32], has noted that each abdominal muscle gets selectively recruited with respect to the direction of displacement. It was found that the TrA and internal oblique muscles are active regardless of perturbation direction, external obliques in antero-lateral, anteromedial, postero-lateral and lateral directions and back extensors in posterior, postero-lateral, postero-medial, & lateral directions. The ADIM has been found to facilitate the co-activation of the TrA and multifidus muscles in stabilizing the trunk [33]. This activation of TrA increases the tension of thoracolumbar fascia creating more loads on abdominal obliques [34]. Recruitment of TrA increases the efficacy of contraction of multifidus to about 4.5 times [35]. The improvement in experimental group was significantly more, as the intensity of load in standing is way more than that in lying. Electromyographic studies have shown the mul-
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tifidus is more loaded and act continuously in upright and anti-gravity activities [36]. The SEBT grid exercises were done in standing and weight bearing position. This is a more functional position mimicking most activities and perturbations, the participants faced in their daily day to day routine. Improvement in muscle endurance needs exercise prescribed with an adequate frequency, intensity and duration [23,36,37] We believe that the dosage of exercises prescribed served as an optimal muscle load to improve endurance. The abdominal muscles and the back muscles have a predominance of type I muscle fibers [39,40]. We hypothesize that exercise training might have increased the number of type I fibers by splitting or proliferation. Further, an improvement in strength is associated with an improvement in muscle endurance. The loss of muscle strength and endurance for the control group was statistically non-significant at follow-up. We relate this loss to non-adherence to the exercise program. The increase in strength in experimental group may be hypothesized to the effect of SEBT grid training in augmenting the ability of the central nervous system (CNS) in planning strategies of muscle activity in advance of movement. We hypothesize this might have translated in to real time planning and execution of tasks, resulting in an increase in strength and endurance, even in the absence of the exercise program. Participants ODI score before intervention was around 22% in both the groups which corresponded to low back pain with disability and post-intervention, it reduced to 12%. 12% has been identified as the cutoff value that distinguishes back pain, with and without disability [41]. However the extent of disability reduction in experimental group was better than the control group. The reduction in disability score was sustained at follow-up for both the groups. The ODI scores reflect the patient’s ability to manage their everyday life while dealing with pain. The reduction in pain may be attributed to the effect of mobilization therapy, stretching exercises and other adjunct interventions used in both the groups. Apart from pain relief, manual therapy is also credited with improving proprioception of spine, which further helps in improving the stability and reducing pain and disability [20,42]. The gains in strength and endurance of the abdominal and extensor muscles is critical in reducing disability as they sustain and stabilize the spinal segments during activity as well as against external forces, preventing re-occurrence and further injuries. The find-
ings of the study are consistent with other studies [43, 44] that reported reduction in disability after strength and endurance training program of core muscles. Exercises performed in a pre-established quota-based manner helps in fear-desensitizing process, increasing activity, exercise tolerance and a reduction in the use of pain medication [45] inducing an overall feeling of wellbeing, reducing apprehension and the extent of disability. The better results of experimental group in the reduction of disability may be hypothesized to its role in motor learning. The first phase of motor control, the cognitive phase, focuses on cognitively oriented problems. All elements of the movement performance are organized consciously in this phase with attention to movement sequence, performance, and instruction [46]. The goal of the initial phase of motor relearning in CLBP is to contract the deep muscles cognitively to increase the precision and skill of the contraction of the muscles. This was accomplished by the ADIM, which selectively initiates the TrA and the core muscles are activated with respect to specific directions of limb movement. As the perturbation in SEBT is self-initiated, it may be possible that that the CNS can predict the changes and pre-program itself to the dynamic challenges by activation of core muscles to this postural challenge. It may be hypothesized that, feed forward activities allow the CNS to use specialized strategies for each element of spinal control. We feel the numbers of repetitions during the study intervention and further repetitions during follow-up might have promoted the participants to the associative stage of motor control. Though the movement patterns used in SEBT training is not similar to movements found in activities of daily living [47], we propose that this training might have resulted in skill learning, where the performance of the limb excursions in various directions are transferred to activities of everyday living, where the environment, personal characteristics, or predictability are changed. This is evident from the better ODI scores in the experimental group that showed further reduction in disability at follow-up. None of the patients in experimental group reported back to us for consultation or treatment till the time of writing this article. From the results of the study, we conclude that interventions like manual therapy and exercises are effective in reducing disability in CLBP patients but the strengthening has to be functional and specific to the demands. The result shows that improved strength and endurance was related to lessened back disability. But
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it was not known whether the subjects who improved their strength and endurance were the ones who were able to exercise more effectively because of less pain or whether the strength and endurance improvement led directly to the decreased back pain intensity. The interesting part though is that, though strength and endurance deficits were noted at follow-up, it was not associated with an increase in disability scores. Hence, a cut-off value of core muscles strength and endurance that associates weakness to back pain has to be established. The limitation of this study was that it failed to measure the timing of contraction of each core muscle during SEBT grid training. Excursion distances were not measured too. The study demonstrated that conventional CLBP treatment combined with trunk muscle training with SEBT grid is clinically advantageous in improving the strength and endurance of abdominal and back muscles as well as reducing the extent of disability in patients with CLBP. We recommend SEBT grid training as an intervention measure in patients with CLBP and a future study on the co-relation between strength and endurance of core muscles and excursion distances in SEBT.
Declaration of interest None.
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Journal of Back and Musculoskeletal Rehabilitation 28 (2015) 521–530 DOI 10.3233/BMR-140551 IOS Press
Effect of trunk muscles training using a star excursion balance test grid on strength, endurance and disability in persons with chronic low back pain G. Shankar Ganesha,∗, Deepak Chhabrab , Monalisa Pattnaika , Patitapaban Mohantya, Rishee Patela and Kumar Mrityunjayc a
SVNIRTAR, Olatpur, P.O. Bairoi, Cuttack Dt., Orissa, India Advanced Certificate Course in Manual Physical Therapy, JSPL, Raigarh, Chattisgarh, India c Nopany Institute of Health Sciences, Girish Park, Kolkata, India b
Abstract. BACKGROUND AND OBJECTIVES: Though core muscles strengthening using upper limbs in various positions and lower limbs in lying have been studied previously in patients with chronic low back pain (CLBP), no study has specifically looked in to the effects of a training program that requires prior motor planning in standing (functional position). The objective of this study was to evaluate the effectiveness of star excursion balance test (SEBT) grid training in improving the outcomes in patients with CLBP. MATERIALS AND METHOD: Sixty patients with mechanical CLBP who fulfilled our criteria were randomized in to two groups; experimental group received physical diagnostic specific interventions, core muscles strengthening and muscles training using the SEBT grid. The participants in control group received stationary cycling instead of SEBT grid training and the other interventions were uniform. The duration of study was 4 weeks. The dependent variables were analyzed using repeated measures 2 × 3 ANOVA. RESULTS: At the end of study, both the groups showed a significant reduction in disability and improvement in strength and endurance (p < 0.05). Post-hoc analysis showed that SEBT grid training was better than conventional exercises. Follow-up at 16 weeks revealed a statistically insignificant loss in strength and endurance in control group patients. This reduction was not associated with an increase in disability score. The experimental group patients continued showing improvement. CONCLUSION: The results of our study show that core muscles strengthening using a SEBT grid are more effective than conventional programs. We hypothesize SEBT training to have a significant role in skill learning. We recommend SEBT grid training to be incorporated in the treatment planning of persons with CLBP. Keywords: Low back pain, exercise, muscle strength, musculoskeletal manipulations, motor skills
1. Introduction
∗ Corresponding author: G. Shankar Ganesh, Department of Physiotherapy, SVNIRTAR, Olatpur, P.O. Bairoi, Cuttack Dt., Orissa, 754010, India. Tel.: +91 9437279869; E-mail: shankarpt@ rediffmail.com.
Chronic low back pain (CLBP) is defined as a persistent and disabling low back pain lasting more than 3 months [1]. CLBP is not related to any underlying pathologies like infection, neoplasm, or fracture [2]. Neurophysiologic studies have linked pain development in the lumbar spine to the disturbances in the
c 2015 – IOS Press and the authors. All rights reserved ISSN 1053-8127/15/$35.00
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mechanoreceptors and impairment of the superior proprioception centers [3]. It has been found that the coordination of low back muscles and postural stability are reduced in patients with CLBP [4,5]. Further, chronic pain is associated with reduced brain gray matter and impaired cognitive ability [6]. Several studies have also indicated abnormal cortical function in people with CLBP [7–11]. Recent evidence suggests that the management of CLBP should focus on supervised exercises and have indicated short-term pain relief from manual therapy approaches [12]. CLBP is a difficult condition to treat with variable results [13] and the expenditure associated with repeated treatment in these patients necessitates an effective treatment strategy. The Star Excursion Balance test (SEBT) [14] is used for dynamic balance assessment and is composed of controlled closed kinetic chain motion activities. A study by the 1st , 2nd and 6th authors [15] showed that patients with CLBP have inferior reach excursions on SEBT when compared to controls. The results were attributed to reduced core muscles strength and proprioceptive deficits in patients with CLBP and we hypothesized that working on SEBT grid would counteract that. Further, no study has specifically studied the effect of core muscles strengthening on a standing lower limb activity that requires prior motor planning. The objective of this study was to find the effectiveness of trunk muscle training using a SEBT grid in persons with CLBP. 2. Methods The study was a prospective trial. Participants who met the following inclusion criteria were recruited for the study: (1) back pain, lasting more than three months and radiating no further below knee, (2) normal neurological examination, (3) age 25–60 years, and (4) mechanical pain provoked with postures, movement and activities. Patients with the following criteria were excluded: (1) patients receiving another treatment apart from standard doses of NSAIDS, (2) pain aggravating in less than 3 minutes of standing, (3) any pathology or surgery at or around spine, pelvis, hip, knee and ankle, (4) acute exacerbation of CLBP, (5) pregnancy, (6) psychiatric disorder and (7) red flags to manual therapy. Sixty patients (36 males and 24 females) with mean age (39.7 ± 8.3) participated and completed the study. Informed consent was obtained from all the participants and the procedure was approved by the institute ethics committee.
Fig. 1. Pressure bio-feedback unit. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/BMR-140551)
2.1. Outcome measures The following dependant variables were assessed for: 2.1.1. Strength and endurance measurement by pressure-biofeedback unit (PBU) Strength and endurance of trunk extensors, transverse abdominis and abdominal obliques were measured by PBU (Chattanooga INC) (Fig. 1) [16]. The accuracy of PBU is described as ± 3 mm Hg and is considered a reliable and valid indicator of muscle function [17,18]. Three investigators with more than 15 years of experience in musculo-skeletal physiotherapy and blinded to the study measured all the outcome measures. The investigators attended a training session prior to the study, where they discussed the measurement procedure. All the data were collected before randomization in a private room with only the investigators present. One investigator gave commands to the participants and the second investigator ensured that contraction was not accompanied by breath hold, pelvic tilt, bracing or substitutionary co-contraction of the gluteus maximus and erector spinae muscles. The third investigator recorded the mean change in mm Hg pressure registered on the device. The participants were positioned as described below. The PBU was inflated to 70 mm of Hg. The participants were instructed to contract the specific muscles. The changes in the pressure reflect the strength of contraction of the muscles and number of repetitions reflects the endurance of the respective muscles. Readings were measured at the completion of a
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Table 1 Physical diagnosis and the criteria for diagnosis Physical diagnosis Lumbar Derangement Syndrome (Posterior) Criteria: Centralization of pain with repetitive extension & peripheralization with repetitive flexion. Flexion Dysfunction Criteria: Loss of trunk flexion with localized pain before achievement of full normal range of flexion. Spondylolisthesis Criteria: Radiograph showing forward shift of upper segments over the lower with or without lysis of pars interarticularis. Soft Disc Lesion Criteria: Lower back with radiating pain where leg pain is more than back pain. Pain aggravated with flexion of the trunk. Spondylosis Criteria: Limitation and pain in extension. Radiograph showing osteophytes and other degenerative changes. Non-Specific Criteria: The problems encountered do not lend itself to a true medical diagnosis. Although clinical presentation of a patient with this condition is fairly easy to recognize, the explanations given for the underlying pathology are controversial and contentious.
No. of patients Experimental Control Total 08 06 14 04
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Fig. 2. Measurement of transverse abdominis muscle strength using PBU. (Colours are visible in the online version of the article; http:// dx.doi.org/10.3233/BMR-140551)
Fig. 3. Measurement of abdominal obliques and back extensors muscle strength using PBU. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/BMR-140551)
10-second contraction over three consecutive contractions, with one minute rest between contractions. The highest score amongst the three 10 second contractions was recorded as strength [18]. No feedback was given to the subjects during data collection [18,19]. Transversus Abdominis (TrA) was tested in prone position (Fig. 2). The inflated cell was placed beneath the abdomen at the level of the anterior superior iliac spine and the patient was instructed to gently and slowly draw the lower abdomen below the navel without moving the upper stomach, back or pelvis [18]. Abdominal Obliques (bilateral external and internal obliques) (Fig. 3) and back extensors (Erector Spinae and Multifidus) (Fig. 3) were tested in supine lying position. The inflated cell was placed at the level of the posterior superior iliac spine. To evaluate the abdomi-
nal obliques, participants were instructed to gently and slowly press the cell, as if to straighten the spine, and for back extensors, the instruction was to lift the weight off the cell like arching the spine, without moving the upper stomach, back or pelvis, while breathing in and out [20]. 2.1.2. Oswestry Disability Index (ODI) The ODI was used to measure patients’ functional disability. ODI is considered the ‘gold standard’ of low back functional outcome tools [21]. 2.2. Procedure The clinicians attended a training session prior to the study, where they discussed the assessment and in-
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G.S. Ganesh et al. / SEBT grid training in CLBP Table 2 Interventions and their indications Technique Exercises − Spinal Flexion − Spinal Extension − McKenzie Extension − Static Trunk Loading Lumbar mobilization (Maitland) − Central PA Vertebral Pressure − Unilateral PA Vertebral Pressure Traction − Supine − Prone Electrotherapy − IFT (4-pole) − TENS Stretching − Rectus Femoris − Piriformis
Indication − Increased lumbar lordosis, Flexion dysfunction − Reduced lumbar lordosis, Extension dysfunction − Posterior Lumbar Derangement Syndrome − Core muscle activation − Bilaterally disturbed symptoms/Hypomobility − Unilaterally disturbed symptoms/Hypomobility Radicular signs, unable to centralize symptoms or muscle spasm − If flexion is pain free, extension is painful − If extension is pain free, flexion is painful or if both flexion and extension are painful − Central back pain/muscle spasm − Pain radiating to Lower Limbs − Tightness as determined by Ely’s Test − Limited hip external rotation with hip in flexion, without any associated spasms Table 3 Dosage parameters
Exercise Extension − Trunk extension in prone − Bilateral lower limb extension in prone − Contralateral lower limb extension in prone − Extension in standing Flexion − Flexion in lying (knee to chest) − Toe touch in long sitting − Flexion in standing − Flexion in step standing McKenzie extension exercises − Prone lying − Repetitive extension in lying Static trunk loading Patient was instructed to lie supine and raise both legs to hip in 90◦ flexion with knees completely flexed and arms raised to 30◦ –40◦ while maintaining the abdominal hollowing and glutei contraction, while maintaining normal breathing. Maitland spinal mobilization − Posterior – anterior central and unilateral
Traction Supine/prone, as per indication Interferential therapy TENS
Stretching Rectus femoris Piriformis
tervention procedure. The participants were randomized in to two different groups by consecutive sampling. Two manipulative physiotherapists with post graduate training in manual therapy and more than 20 years of clinical experience assessed and performed the spinal mobilizations, stretching maneuvers and ap-
Dosage 10 sec hold and 3 repetitions in each position.
10 repetitions in each position
10 repetitions with few seconds hold
Rate: 2–3 oscillations per second Intensity: as tolerated by the patient Duration: 2–3 minutes/vertebra Traction was given statically with 1/2 of body weight as traction force for 10 minutes 15 minutes Pulse duration – 40 usec Frequency – 100 Hz Treatment duration – 20 min 6–10 repetitions of 6 second hold and 5 seconds rest
plied all the electro-therapeutic modalities. The assessment involved analysis of the subject’s pain provocative postures, movements, functional tasks and radiographs to arrive at a specific physical diagnosis and where the assessment was in-conclusive, a diagnosis of non-specific low back pain was given . The SEBT
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Table 4 Results of the study Variable Transversus Abdominis Strength (Figure-5) Transversus Abdominis Endurance (Figure-6) Abdominal Obliques Strength (Figure-7) Abdominal Obliques Endurance (Figure-8) Back Extensor Strength (Figure-9) Back Extensor Endurance (Figure-10) ODI (Figure-11)
Time (f value) 225.078 (p = 0.00) 376.017 (p = 0.00) 164.802 (p = 0.00) 236.478 (p = 0.00) 582.470 (p = 0.00) 222.983 (p = 0.00) 398.670 (p = 0.00)
Group (f value) 164.829 (p = 0.00) 129.538 (p = 0.00) 266.278 (p = 0.00) 237.636 (p = 0.00) 196.224 (p = 0.00) 371.541 (p = 0.00) 39.679 (p = 0.00)
Time X Group (f value) 200.56 (p = 0.00) 179.036 (p = 0.00) 122.104 (p = 0.00) 242.261 (p = 0.00) 392.058 (p = 0.00) 127.877 (p = 0.00) 5.164 (p = 0.01)
Fig. 4. Eight excursion directions for both feet.
grid training, cycling, static trunk loading and McKenzie extension exercises were supervised by a musculoskeletal physiotherapist with more than 12 years of clinical experience. Tables 1, 2 and 3 summarize the physical diagnoses, criterion for diagnosis, respective interventions and dosages prescribed to study participants. Group I (30 subjects, 11 females and 19 males. mean age 38.53 ± 8.30) received diagnosis specific interventions, core muscles strengthening and SEBT grid training. Group II (30 subjects, 13 females and 17 males. mean age 40.86 ± 8.55) received diagnosis specific interventions, core muscle strengthening and stationary cycling at their own pace for 15 minutes. All participants received the intervention for a period of five sessions per week for 4 weeks. The SEBT grid used for this study was constructed in the department using a protractor and 3-inch-wide black color adhesive tape. The grid consisted of eight lines (directions) laid on the floor extending at 45◦ increments from the center (Fig. 4). This exercise required subjects to do an abdominal drawing in maneuver (ADIM) and maintain balance on a single limb (stance leg) while trying to reach as far as possible with the most distal part of their reach foot and touch
as lightly as possible to ensure they are not using that leg for support. The subjects then returned to bilateral stance while maintaining balance. A verbal and visual demonstration of the testing procedure was given to each subject by one of the authors. All participants in the experimental group made 10 repetitions in each direction with a five to ten seconds rest period in between. Once all the sets with one foot were completed, the same procedure was repeated with stance on the other foot after 3 minutes of rest. The exercise was performed once daily, 5 times per week for 4 weeks. All the measurements were taken prior to the beginning of the intervention, and at 4th and 16th weeks. At the end of the program, all subjects were taught self stretching, core strengthening exercises and received individual instructions regarding maintenance of optimal posture and ergonomic advice. Participants were encouraged to follow these instructions, continue the exercises and avoid immobility. 2.3. Statistical analysis The data was analyzed with SPSS (Statistical Package for Social Sciences) 16.0 version. The dependent variables were analyzed using repeated measures 2 × 3
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Strength of Transversus Abdominis
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Fig. 7. Graph showing changes in abdominal obliques muscle strength before and after intervention and at follow-up. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/ BMR-140551)
Abdominal Obliques Endurance
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number of repetitions
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Fig. 5. Graph showing changes in Transverse abdominis muscle strength before and after intervention and at follow-up. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/ BMR-140551)
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Fig. 6. Graph showing changes in Transverse abdominis muscle endurance before and after intervention and at follow-up. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/ BMR-140551)
Fig. 8. Graph showing changes in abdominal obliques muscle endurance before and after intervention and at follow-up. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/ BMR-140551)
ANOVA. All pair wise post hoc comparison was done using a 0.05 level of significance.
group for all the outcome measures and this main effect achieved significant group X time interaction. Tukeys post-hoc analysis showed that experimental group was better than the control group in improving the outcomes. The control group showed statistically insignificant reduction in strength and endurance at follow-up, while the experimental group continued to improve. However, the ODI scores showed a further reduction at follow-up.
3. Results Sixty participants were enrolled for the study and there was no drop out of patients till follow-up. The mean duration of pain in the experimental group was 7.3 months and 6.8 months in the control group. A one-way ANOVA revealed that both the groups did not differ in baseline measures. Participants from both the groups admitted their inability to stick to their instructed home based self-exercise programs as per regime. The overall results (Table 4) (Figs 5–11) of the study showed that there was a main effect for the time and
4. Discussion This is the first study to present the results of the efficacy of SEBT grid training on CLBP. The results support the hypothesis that a 4-week SEBT grid training offers greater clinical benefits to CLBP patients than
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Fig. 9. Graph showing changes in back extensors muscle strength before and after intervention and at follow-up. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/BMR140551)
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Fig. 10. Graph showing changes in back extensors muscle strength before and after intervention and at follow-up. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/BMR140551)
the conventional program. The significant improvements by SEBT subjects were maintained at the 16week follow-up, indicating that the SEBT grid training is associated with longer lasting reductions in disability. In addition, subjects felt working in the SEBT grid was more sportive due to its competitive nature. Exercise physiologists suggest that to improve muscle strength, a load that exceeds the metabolic capacity of the muscle must be applied. Studies have experimentally demonstrated that skeletal adaptations can occur in various skeletal muscle fibers types at four weeks, if the training intensity is sufficient [22, 23]. The American college of sports medicine guidelines [24] and Chromiak [25] stated that 8–12 repetitions of specific exercise once daily is sufficient to bring about muscle strength, when done five times a week. The participants were prescribed exercises tar-
Experimental
Control
Fig. 11. Graph showing changes in Oswestry disability index before and after intervention and at follow-up. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/BMR140551)
geting the core muscles with a dosage that satisfied the above criteria, leading to strength gains. Mobilization to spine influences pain relief through its mechanical and neuro-physiological mechanisms [26,27] and prior manual therapy to lumbar spine increases the activity of multifidus [28]. Lumbar extension training session of one per week has been found sufficient to improve strength [29] and improvement in strength is associated with decreased pain scores in CLBP [30]. Harman, 2009 [31] proposed that the use of electrophysiological agents in the treatment of CLBP has a positive effect if used as an adjunct to manual therapy and exercises. The superior strength gain in the SEBT grid training may be attributed to the multi-directional reaching along with the ADIM done by the participants. Carpenter et al. [32], has noted that each abdominal muscle gets selectively recruited with respect to the direction of displacement. It was found that the TrA and internal oblique muscles are active regardless of perturbation direction, external obliques in antero-lateral, anteromedial, postero-lateral and lateral directions and back extensors in posterior, postero-lateral, postero-medial, & lateral directions. The ADIM has been found to facilitate the co-activation of the TrA and multifidus muscles in stabilizing the trunk [33]. This activation of TrA increases the tension of thoracolumbar fascia creating more loads on abdominal obliques [34]. Recruitment of TrA increases the efficacy of contraction of multifidus to about 4.5 times [35]. The improvement in experimental group was significantly more, as the intensity of load in standing is way more than that in lying. Electromyographic studies have shown the mul-
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tifidus is more loaded and act continuously in upright and anti-gravity activities [36]. The SEBT grid exercises were done in standing and weight bearing position. This is a more functional position mimicking most activities and perturbations, the participants faced in their daily day to day routine. Improvement in muscle endurance needs exercise prescribed with an adequate frequency, intensity and duration [23,36,37] We believe that the dosage of exercises prescribed served as an optimal muscle load to improve endurance. The abdominal muscles and the back muscles have a predominance of type I muscle fibers [39,40]. We hypothesize that exercise training might have increased the number of type I fibers by splitting or proliferation. Further, an improvement in strength is associated with an improvement in muscle endurance. The loss of muscle strength and endurance for the control group was statistically non-significant at follow-up. We relate this loss to non-adherence to the exercise program. The increase in strength in experimental group may be hypothesized to the effect of SEBT grid training in augmenting the ability of the central nervous system (CNS) in planning strategies of muscle activity in advance of movement. We hypothesize this might have translated in to real time planning and execution of tasks, resulting in an increase in strength and endurance, even in the absence of the exercise program. Participants ODI score before intervention was around 22% in both the groups which corresponded to low back pain with disability and post-intervention, it reduced to 12%. 12% has been identified as the cutoff value that distinguishes back pain, with and without disability [41]. However the extent of disability reduction in experimental group was better than the control group. The reduction in disability score was sustained at follow-up for both the groups. The ODI scores reflect the patient’s ability to manage their everyday life while dealing with pain. The reduction in pain may be attributed to the effect of mobilization therapy, stretching exercises and other adjunct interventions used in both the groups. Apart from pain relief, manual therapy is also credited with improving proprioception of spine, which further helps in improving the stability and reducing pain and disability [20,42]. The gains in strength and endurance of the abdominal and extensor muscles is critical in reducing disability as they sustain and stabilize the spinal segments during activity as well as against external forces, preventing re-occurrence and further injuries. The find-
ings of the study are consistent with other studies [43, 44] that reported reduction in disability after strength and endurance training program of core muscles. Exercises performed in a pre-established quota-based manner helps in fear-desensitizing process, increasing activity, exercise tolerance and a reduction in the use of pain medication [45] inducing an overall feeling of wellbeing, reducing apprehension and the extent of disability. The better results of experimental group in the reduction of disability may be hypothesized to its role in motor learning. The first phase of motor control, the cognitive phase, focuses on cognitively oriented problems. All elements of the movement performance are organized consciously in this phase with attention to movement sequence, performance, and instruction [46]. The goal of the initial phase of motor relearning in CLBP is to contract the deep muscles cognitively to increase the precision and skill of the contraction of the muscles. This was accomplished by the ADIM, which selectively initiates the TrA and the core muscles are activated with respect to specific directions of limb movement. As the perturbation in SEBT is self-initiated, it may be possible that that the CNS can predict the changes and pre-program itself to the dynamic challenges by activation of core muscles to this postural challenge. It may be hypothesized that, feed forward activities allow the CNS to use specialized strategies for each element of spinal control. We feel the numbers of repetitions during the study intervention and further repetitions during follow-up might have promoted the participants to the associative stage of motor control. Though the movement patterns used in SEBT training is not similar to movements found in activities of daily living [47], we propose that this training might have resulted in skill learning, where the performance of the limb excursions in various directions are transferred to activities of everyday living, where the environment, personal characteristics, or predictability are changed. This is evident from the better ODI scores in the experimental group that showed further reduction in disability at follow-up. None of the patients in experimental group reported back to us for consultation or treatment till the time of writing this article. From the results of the study, we conclude that interventions like manual therapy and exercises are effective in reducing disability in CLBP patients but the strengthening has to be functional and specific to the demands. The result shows that improved strength and endurance was related to lessened back disability. But
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it was not known whether the subjects who improved their strength and endurance were the ones who were able to exercise more effectively because of less pain or whether the strength and endurance improvement led directly to the decreased back pain intensity. The interesting part though is that, though strength and endurance deficits were noted at follow-up, it was not associated with an increase in disability scores. Hence, a cut-off value of core muscles strength and endurance that associates weakness to back pain has to be established. The limitation of this study was that it failed to measure the timing of contraction of each core muscle during SEBT grid training. Excursion distances were not measured too. The study demonstrated that conventional CLBP treatment combined with trunk muscle training with SEBT grid is clinically advantageous in improving the strength and endurance of abdominal and back muscles as well as reducing the extent of disability in patients with CLBP. We recommend SEBT grid training as an intervention measure in patients with CLBP and a future study on the co-relation between strength and endurance of core muscles and excursion distances in SEBT.
Declaration of interest None.
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