Effects of Abdominal Draw-In Maneuver in. Combination With Ankle Dorsiflexion in. Strengthening the Transverse Abdominal

Transcription

1 Effects of Abdominal Draw-In Maneuver in Combination With Ankle Dorsiflexion in Strengthening the Transverse Abdominal Muscle in Healthy Young Adults and Patients With Low Back Pain Seungchul Chon The Graduate School Yonsei University Department of Rehabilitation Therapy

2 Effects of Abdominal Draw-In Maneuver in Combination With Ankle Dorsiflexion in Strengthening the Transverse Abdominal Muscle in Healthy Young Adults and Patients With Low Back Pain Seungchul Chon The Graduate School Yonsei University Department of Rehabilitation Therapy

3 Effects of Abdominal Draw-In Maneuver in Combination With Ankle Dorsiflexion in Strengthening the Transverse Abdominal Muscle in Healthy Young Adults and Patients With Low Back Pain A Dissertation Submitted to the Department of Rehabilitation Therapy and the Graduate School of Yonsei University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Seungchul Chon June 2011

4 This certifies that the doctoral dissertation of Seungchul Chon is approved. Thesis Supervisor: Sunghyun (Joshua) You Suhnyeop Kim Minye Jung Hyeson Jeon Duckwon Oh The Graduate School Yonsei University June 2011

5 Acknowledgements First of all, I thank and praise God for preparing and guidance this thesis. This thesis would not have been possible without individuals who offered their valuable assistance and strong support to prepare and complete this study. It is great pleasure to express my sincere gratitude to them in my humble acknowledgement. First and foremost I would like to convey my gratitude to my advisor, Dr. Sunghyun (Joshua) You for his excellent guidance, advice and supervision throughout this research work. He has supported me with his expertise and patiently encouraged me to bring out my best, allowing me to grow as a researcher and a scholar. The tireless passion and enthusiasm for his research was an important key which motivated me to pursue my degree. I would never have productive experience without his crucial contributions of time and ideas. I gratefully acknowledge Professor Suhnyeop Kim, Professor Minye Jung, Professor Hyeson Jeon, and Professor Duckwon Oh for their faith in me to be a good scholar. Their endless passion and commitment in physical therapy has been driving force for me to keep moving forward when frustrated. I would like to thank for their valuable advice and critical comments on my paper. I would also like to thank Professor Chunghwi Yi, Professor Ohyun Kwon, Professor Sanghyun Cho, and Professor Heonseock Cynn for being a great mentor with best suggestion and their

6 willingness to share their valuable insight with me. I believe my intellectual maturity has been nourished through their sincere advice. I am indebted to professors at Woosong University for their strong support and encouragement with their best wishes. My special thanks go to students at Woosong who help to implement and complete my experiment. Last but not the least, I would like to show my deepest gratitude to my family. This dissertation would be impossible without them. I would like to thank my father for his thoughtful support with love and care. I would also like to thank my mother for sincerely raising me and standing by me in joy and sorrow. No words can describe my mother s everlasting love to me. Many thanks go to my brother for always cheering me up. I owe my loving thanks to my wife. My wife has lost me a lot due to my research even during her pregnancy. She has been unselfish and dedicated herself to support my study. Without her understanding and persistent confidence in me, I would never finish this work. My special thanks to my newborn son for being healthy and showing me the best smile in the world.

7 Table of Contents List of Figures iv List of Tables vi Abstract viii Chapter Ⅰ. Introduction 1 Chapter Ⅱ. Effects of the Abdominal Draw-In Maneuver in Combination With Ankle Dorsiflexion in Strengthening the Transverse Abdominal Muscle in Healthy Young Adults Introduction 4 Method 8 1. Participants 8 2. Intervention Ultrasound Imaging Measurement Electromyographic Measurement Statistical Analysis 16 Results Ultrasound Imaging Data Test-Retest Reliability Electromyographic Data 23 Discussion 24 - i -

8 Chapter Ⅲ. Use of Co-contraction of Ankle Dorsiflexors to Increase Transverse Abdominis Function in Low Back Pain Introduction 28 Method Participants Intervention Pain and Function Assessment Ultrasound Imaging Measurement Electromyographic Measurement Statistical Analysis 48 Results Clinical Data Ultrasound Imaging Data Test-Retest Reliability Electromyographic Data 55 Discussion 58 Chapter IV. Conclusion 64 References 65 Appendices 79 Appendix A. Pain Disability Index 80 Appendix B. Pain Rating Scale 83 Appendix C. Multivariate tests of ANOVA in SPSS 88 - ii -

9 Appendix D. Independent t-test in SPSS 89 Appendix E. Review Form Clinical Trial Research Plan 94 Appendix F. Declaration of Ethical Conduct in Research 97 Abstract in Korean 98 - iii -

10 List of Figures Figure 1. Electromyographic measurement of muscle activity 15 Figure 2. Thickness of the transverse abdominal muscle, internal oblique muscle and external oblique muscle in the experimental and control groups 18 Figure 3. Bland and Altman plot showing the reliability of ultrasound image measurement for the thickness of the transverse abdominal muscle imaged in two abdominal draw-in maneuver interventions 20 Figure 4. Bland and Altman plot showing the reliability of ultrasound image measurement for the thickness of the internal oblique muscle imaged in two abdominal draw-in maneuver interventions 21 Figure 5. Bland and Altman plot showing the reliability of ultrasound image measurement for the thickness of the external oblique muscle imaged in two abdominal draw-in maneuver interventions 22 Figure 6. Flow diagram for this study 35 Figure 7. EMG biofeedback during the resisted dorsiflexion training to augment transverse abdominis muscle contraction 37 - iv -

11 Figure 8. Participant positioning during co-contraction biofeedback training 38 Figure 9. Placement of ultrasound transducer on abdominal muscle 43 Figure 10. Abdominal muscle thickness measurement 43 Figure 11. Placement of EMG electrodes 47 - v -

12 List of Tables Table 1. Demographic data of participants 9 Table 2. Comparison of muscle thickness ( cm ) in the transverse abdominal, internal oblique and external oblique muscles between the experimental and control groups 18 Table 3. Comparison of transverse abdominal electromyographic amplitudes (root mean square) in the experimental group 23 Table 4. The demographic and clinical characteristics of subjects 34 Table 5. Comparison of pain data obtained from VAS, PDI, and PRS measures between the pre-/post-intervention in the LBP group 50 Table 6. Comparison of the abdominal muscle contraction thickness ( mm ) between the groups 52 Table 7. Comparison of baseline muscle rest thickness ( mm ) and muscle contraction thickness of the abdominal muscles between groups at the pretest 53 Table 8. EMG peak amplitude, mean amplitude, and onset time data (root-mean-square, RMS) between groups during the co-contraction training 56 Table 9. Mean EMG latency between groups during the co-contraction training 57 - vi -

13 ABSTRACT Effects of Abdominal Draw-In Maneuver in Combination With Ankle Dorsiflexion in Strengthening the Transverse Abdominal Muscle in Healthy Young Adults and Patients With Low Back Pain Seungchul Chon Dept. of Rehabilitation Therapy (Physical Therapy Major) The Graduate School Yonsei University The abdominal draw-in maneuver (ADIM) is the most common in the core stabilization exercise. However, applying ADIM to the patients with low back pain (LBP) is not easy due to pain factor and weakness of deep abdominal muscle. These - vii -

14 studies were designed to examine the effect of new method of ADIM combined with resisted ankle dorsiflexion training on the deep abdominal muscle. In the first study, forty healthy adults were allocated at random to the experimental group or the control group. The experimental group performed the ADIM in combination with ankle dorsiflexion, and the control group performed the ADIM alone, five times a day. Ultrasound (US) image and electromyography (EMG) were used to determine the intervention-related changes in muscle activity and the thickness of abdominal muscles during the ADIM or the ADIM in combination with ankle dorsiflexion. A significant difference was found in the thickness of the transverse abdominal (TrA) muscle between the groups (mean difference 0.24 cm ). A significant difference was demonstrated in the amplitude of the TrA/internal oblique (IO) muscle contraction between the two techniques in the experimental group (mean difference mv ). The intra-class correlation coefficient showed excellent test retest reliability of US image measurement of the abdominal muscles: 0.96 for the TrA muscle, 0.87 for the IO muscle and 0.77 for the EO muscle. In the second study, both the LBP group and the healthy group received ten 30- minute sessions of ADIM combined with ankle dorsiflexion over a two-week period. A separate mixed-model analysis of variance was computed for the TrA, IO, and EO muscle thicknesses. The differences in mean and peak EMG amplitudes, onset time, and latency were compared between the groups. The visual analog pain scale, - viii -

15 pain disability index, and pain rating scale were used to assess pain in the LBP group before and after the intervention. There was a significant interaction between the LBP group and the healthy groups and a main effect for pre-/post-test were obtained for only TrA muscle thickness change. Significant differences in mean and peak EMG amplitudes, onset time, and latency were achieved between the groups. Significant reductions in all pain measures were observed after training. This is the first clinical study to demonstrate that ADIM combined with ankle dorsiflexion training may result in a morphological change in the TrA muscle and associated pain management in patients with LBP. Key Words: Abdominal draw-in maneuver, Ankle dorsiflexion, Electromyography, Low back pain, Transverse abdominal muscle, Ultrasound image. - ix -

16 Chapter Ⅰ Introduction Low back pain (LBP) is common, costly, and leading cause of musculoskeletal system impairment and disability in sports activities and heavy physical loading (Cairns, Foster, and Wright 2006; Critchley, and Coutts 2002). Epidemic studies showed that in the United States alone, as many as 30-50% athletes suffer from LBP (d'hemecourt, Gerbino, and Micheli 2000; Dreisinger, and Nelson 1996). The annual healthcare cost related to LBP is estimated to be nearly 100 billion dollars per year (Martin et al. 2008). The lumbo-pelvic core instability has been consistently identified as an important clinical marker for chronic LBP. Core stability exercise that can effectively improve lumbo-pelvic instability is thus a hallmark of clinical sports medicine and rehabilitation in athletes with LBP and core instability. LBP therapeutic techniques are used to optimize spinal stability and reduce pain (Hides et al. 2006; Hodges, and Richardson 1996; Pengel et al. 2003), but outcome measures are inconclusive and do not support the superiority of one intervention over another (Cairns, Foster, and Wright 2006; Ferreira et al. 2007). Chronic LBP is related to not only discogenic pain but also core instability. Nevertheless, clinical studies focus on pain reduction and do not target the core instability associated with transverse abdominis (TrA) dysfunction (Kiesel et al. 2008; Richardson et al. 2004; - 1 -

17 Teyhen et al. 2005). There is growing evidence that the ADIM can help in the selective restoration of the neuromuscular control of the abdominal and mulifidus muscle groups among individuals with LBP, thereby improving spinal stability. However, it is often difficult to administer the ADIM and other core exercises to patients with LBP because of the pain factor and the impaired neuromuscular control of the core muscles. The ADIM combined with ankle dorsiflexion training is derived from irradiation, via the proprioceptive neuromuscular technique (PNF), which has been widely used to empower the weakened core muscles by selectively stimulating adjacent or stronger muscles in the lower extremities (Adler, Beckers, and Buck 2008). The success of this method suggests the potential of a lumbar stabilization exercise for treating LBP (Chon, Chang, and You 2010). Specifically, irradiation is defined as the propagation and augmentation of muscle strength in response to resistance, possibly resulting from stimulus (resistance)-induced temporal or spatial summation in muscle fibers (Adler, Beckers, and Buck 2008; Eccles, and Sherrington 1930; Shimura K, and Kasai 2002). It is thus believed to increase the number of motor units activated in a neuromuscular response. Building on this notion, it is possible that irradiation can be used to selectively contract the deep target muscle, the TrA, by applying resistance to the relatively stronger ankle dorsiflexors when combined with the ADIM, thereby further augmenting lumbar spinal stability. Enhanced TrA neuromuscular control patterns among individuals with LBP are significantly associated with the reduction - 2 -

18 of pain and increase in functional spinal mobility and associated physical activity (Hides et al. 2006; Hodges, and Richardson 1996). Work to ascertain the motor control mechanisms that underpin the therapeutic effects of the ADIM combined with ankle dorsiflexion training has important clinical ramifications for the prevention of and interventions for mechanical LBP. The specific aim of this clinical trial was to examine the effect of the ADIM combined with ankle dorsiflexion training on pain intensity and physical disability among individuals with mechanical LBP using ultrasound (US) image and electromyography. In these studies, we hypothesized that the ADIM combined with ankle dorsiflexion training would lead to greater improvement in core stability, as evidenced by muscle thickness, electromyographic data, pain reduction, and physical function, than conventional ADIM alone

19 Chapter Ⅱ Effects of the Abdominal Draw-In Maneuver in Combination With Ankle Dorsiflexion in Strengthening the Transverse Abdominal Muscle in Healthy Young Adults (Experimental Study 1) Introduction The abdominal draw-in maneuver (ADIM) is commonly used during core stabilization techniques to restore neuromuscular control in the core stabilization musculature of athletes with sports injuries. The maneuver has also recently gained widespread acceptance in reducing symptoms in patients with low back pain (LBP) (Macedo et al. 2009; von Garnier et al. 2009). Recent evidence on the conservative - 4 -

20 management of LBP suggests that the restoration of neuromuscular control in the transverse abdominal (TrA) muscle, together with minimal contraction of other superficial oblique, internal and external abdominal muscles, is essential for effective treatment during the early stages of rehabilitation (Cresswell, Grundström, and Thorstensson 1992; Hodges 2001; Hodges, and Richardson 1996). Previous studies have demonstrated that the use of the ADIM, in particular, is far more effective than the use of general core stabilization techniques in improving the cross-sectional area of the TrA muscle (Akuthota, and Nadler 2004; Hodges, Cresswell, and Thorstensson 1999; Hodges, and Richardson 1996). Thus, core stabilization techniques that incorporate the selective motor recruitment of the central core stabilizer, such as the TrA muscle, may be beneficial in the effective management of LBP. A variety of core stabilization techniques, including abdominal bracing, curl-ups, lateral bridges, wall squats and stabilization exercises using a ball (Akuthota, and Nadler 2004; Standaert, and Herring 2007), are used in conjunction with or without US image (Mannion et al. 2008; O Sullivan et al. 1997; Urquhart et al. 2005), although outcome studies have failed to provide clinical evidence for the superiority of any particular technique. In addition, despite the fact that all of these stabilization exercises have been used in the management of individuals with LBP, it is difficult to reach a clinical decision about adopting any one of them because their therapeutic efficacy has yet to be demonstrated. For example, ascertaining the exact or underpinning therapeutic effect of core stabilization techniques poses a significant challenge because these techniques are often incorporated into static and dynamic - 5 -

21 neuromuscular or strengthening regimens (Hibbs et al. 2008; Hodges 2001; Hodges, and Richardson 1996). Such combinations can potentially confound the results about which type of core stabilization technique is more effective for the selective recruitment of core stabilizers. The irradiation technique, a form of proprioceptive neuromuscular facilitation, has been conventionally used to selectively increase the number of active motor unit recruitments involved or weakened in the neuromuscular response (Moore 1975; Shimura, and Kasai 2002). Irradiation is defined as the increasing spread and strength of the response to the stimulation (resistance) (Buchwald 1967; Hopf, Schlegel, and Lowitzsch 1974; Moore 1975; Shimura, and Kasai 2002), and possibly results from stimulus (resistance)-induced temporal or spatial summation (Eccles, and Sherrington 1930). It is also possible that the irradiation technique may empower or stimulate the deep target TrA muscle selectively through the application of resistance to the relatively stronger ankle dorsiflexors when used in combination with the ADIM, thus further augmenting lumbar spinal stability. Research is needed to determine the motor control mechanisms underpinning the therapeutic effects of the irradiation technique, which has important clinical ramifications for the prevention and management of lumbar spinal instability. This study was undertaken to determine the additive effect of a combination of ankle dorsiflexion and the ADIM on lumbar stabilization and abdominal muscle motor control patterns in healthy young adults. Lumbar stabilization and the motor control patterns in abdominal muscles were - 6 -

22 determined by measuring muscle thickness and muscle activity using US image and electromyography (EMG), respectively, in experimental and control groups. The basic hypothesis was that the selective increase in thickness and amplitude in the TrA muscle would be greater in the experimental group (which performed both the ADIM and ankle dorsiflexion) compared with the control group (which performed the ADIM alone)

23 Method 1. Participants This study was a cross-sectional study with an experimenter-blinded design. A convenience sample of 40 healthy young adults was recruited from a local university. All of the participants gave their informed consent, and the study protocol was approved by the university ethics and institutional review board. The investigators responsible for assessing the outcomes were unaware of an individual s group assignment. Random allocation was implemented using the conventional randomization directory method in which a random number table was used to produce one code card for each participant, who then picked a card to receive his or her group assignment. Experimenter blinding success was evaluated by asking the outcome assessors which intervention they thought had been provided. The participants, all of whom were free from any known medical problems, were allocated at random into the experimental group (n 1 =20) or the control group (n 2 =20). Those with any neuro-musculoskeletal pathology or history of spinal surgery were excluded. The target sample size was estimated based on a power of 87% at α=0.05 to detect large differences in effect size between the groups (Cohen 1977). Table 1 presents the demographic characteristics of the participants

24 Table 1. Demographic data of participants Experimental (n 1 =20) Control (n 2 =20) Age (years) ± 1.59 a ± 1.88 Height ( cm ) ± ± 7.92 Weight ( kg ) ± ± 9.14 a Mean ± SD - 9 -

25 2. Intervention Both groups performed an US-guided (visual feedback) ADIM for 30 minutes per day, 5 days per week over a 2-week period, with ankle dorsiflexion added in the experimental group. The success of the ADIM was assessed by monitoring muscle thickness using US image, and irradiation was evaluated by monitoring the recruitment sequence of activation of the tibialis anterior (TA), rectus femoris (RF) and TrA/internal oblique (IO) muscles of the right lower extremity. During the ADIM, participants were asked to adopt a crook-lying position, and a pressure biofeedback unit set to range from 40 to 70 mmhg (Richardson et al. 1992; Richardson, Hodges, and Hides 2004) was placed beneath their fifth lumbar vertebra to monitor lumbar movement during the measurement of ADIM performance. Participants were instructed to draw in their lower abdomen below the navel gently and gradually without moving their upper abdomen or spine, while maintaining a neutral pelvic position to attempt to keep the target pressure range (40 to 70 mmhg). They were then asked to dorsiflex their ankle joint against the resistance (with 50% maximal voluntary isometric contraction (MVIC) of the TA provided by a fixed-strap band. The irradiation or propagation order of muscle recruitment or the sequential activation of the TA, RF and TrA/IO muscles was closely assessed through real-time EMG

26 3. Ultrasound Imaging Measurement A Logiq US imaging system (α 200, Samsung-GE Medical Systems Inc., Seongnam, Korea) with a 7.5-MHz linear transducer was used to assess muscle thickness and to provide accurate visual feedback during the intervention. The thicknesses of the abdominal muscles, including the IO and external oblique (EO) muscles, were obtained. The participants were asked to adopt a relaxed crook-lying position (Richardson, Hodges, and Hides 2004). Their hip and knee joints were positioned between 40 and 80 degrees to reduce the lumbar lordosis. The inferior borders of the rib cage and iliac crest on the right side were palpated as reference points (Whittaker 2007). US gel (AQUASONIC 100, Parker Inc., Orange, NJ) was applied to the transducer head, which was transversely positioned 25 mm anteromedial to the midway point between the 12th rib and the iliac crest (McMeeken et al. 2004; Whittaker 2007). The transducer head was maneuvered until the sharpest images of the lateral abdominal muscles (EO, IO and TrA muscles) were obtained (Teyhen et al. 2005). Three scans were taken on the right side of the abdominal muscles in their relaxed state in reference to a predetermined benchmark. The scanning location at the pretest was marked on a transparent sheet for the posttest to ensure identical placement throughout the entire experiment (Rankin, and Stokes 1998). To control for the potential influence of respiration on muscle thickness, the images were consistently

27 acquired at the end of expiration, which was determined through visual inspection of the US image (Whittaker 2007). The image data acquired were stored, and muscle thickness ( cm ) was measured using an on-screen caliper. The thicknesses of all three muscles were defined by drawing a vertical reference line that was located 2.5 cm from the left edge (the muscle fascia junction) of the TrA (Whittaker 2007). An immediate readout of the muscle thickness was displayed on the screen and stored for further analysis. Data that were unacceptable due to movement artifact were discarded, and the scan was then repeated. Based on this protocol, a test retest reliability study was conducted to determine the degree of reliability between the preand post-tests of US image measurements of abdominal muscle thickness in normal young adults, including those of the EO, IO and TrA muscles. Intra-class correlation coefficient (ICC) statistical analysis revealed good to excellent ICCs ranging from 0.77 to

28 4. Electromyographic Measurement A surface EMG with a WEMG-8-type cable (WEMG-8 System, Laxtha Inc., Daejeon, South Korea) was used to record the onset times and amplitudes of the contractions of the TA, RF and TrA/IO muscles. These measurements were only collected for the experimental group to determine whether sequential activation of these muscles occurred during ankle dorsiflexion (Figure 1). During data analysis, the amplitude data were used to evaluate the meaningful changes in the selective motor control patterns of the TrA/IO, whereas the onset time data were simply used to monitor the firing sequence (i.e. TrA/IO TA RF augmented TrA/IO). To reduce skin impedance, each participant s skin was shaved, sanded and cleaned, and electrode gel was applied. If the measured impedance was greater than 5 kω, the electrode was removed and the skin preparation procedure was repeated. A pair of active electrodes (inter-electrode distance=2.0 cm ) was placed over the tested muscle bellies in parallel (Marshall, and Murphy 2003), and a reference electrode was positioned over the lateral ankle malleolus. Telescan 2.89 software (Laxtha Inc.) was used to acquire EMG signals at a sampling frequency of 1024 Hz and to process them with a 60-Hz notch filter. The root mean square EMG amplitude for the TrA/IO muscle was calculated for 2 seconds (4 to 6 seconds duration, interval 1) during the ADIM and for 2 seconds (13 to 15 seconds, interval 4) during the ADIM in combination with ankle dorsiflexion (Figure 1). The sequential activation of TA, RF

29 and TrA/IO muscle activities was displayed on a computer monitor. Participants were instructed to sustain 30% MVIC of the TrA/IO muscle during the ADIM, followed by 50% MVIC of the TA, RF and TrA/IO muscles during ankle dorsiflexion, and then to rest for 5 seconds. An automatic auditory cue was used to trigger each contraction event, which lasted for 3 seconds over a 20-seconds period (Figure 1)

30 Figure 1. Electromyographic (EMG) measurement of muscle activity. Raw EMG data are shown for a representative subject from the experimental group, who performed the abdominal draw-in maneuver (ADIM) in combination with ankle dorsiflexion. The five vertical solid lines indicate the time at which an automatic auditory cue from the EMG software was sequentially given for the ADIM, tibialis anterior (TA) contraction, rectus femoris (RF) contraction, transverse abdominal (TrA)/internal oblique (IO) contraction, and release (or rest), respectively

31 5. Statistical Analysis Standard statistical analysis included computation of the means and standard deviations, an independent sample t-test or paired two-tailed t-test, and ICC analysis (McMeeken et al. 2004). The independent t-test was used to assess the mean differences in muscle thickness between the experimental and control groups. The paired t-test was used to examine the mean difference in the EMG amplitude of the TrA/IO muscle between pre- and post-intervention in the experimental group. ICC analysis and a Bland and Altman test (Bland, and Altman 1986; von Garnier et al. 2009) were used to examine the test retest reliability of the US image measurements of abdominal muscle thickness. Repeated-measures analysis of variance, ICC=(2, 1) (two-way random, single measure), was undertaken and the 95% confidence interval (CI) of the difference between the two measurements was calculated (Hopkins 2003; Shrout, and Fleiss 1979). Bland and Altman plots, including the mean difference and the limits of agreement, were calculated to provide an estimate of the error between repeated measurements (Bland, and Altman 1986) using MedCalc for Windows Version (MedCalc Software, Mariakerke, Belgium) Statistical Package for the Social Sciences Version 12.0 (SPSS release 12.0, SPSS Inc., Chicago, IL, USA) was used, with statistical significance set at p<

32 Results 1. Ultrasound Imaging Data The independent t-tests consistently revealed a significant difference in the thickness of the TrA muscle between the groups (mean difference=0.24 cm, 95% CI 0.08 to 0.40 cm, p=0.01), which indicates that the combination of the ADIM and ankle dorsiflexion was more effective in improving selective recruitment of the TrA muscle than the ADIM alone (Table 2). However, no significant difference in the thickness of the IO muscle ( 0.13 cm, 95% CI 0.29 to 0.02 cm, p=0.09) or the EO muscle ( 0.00 cm, 95% CI 0.09 to 0.09 cm, p=0.94) was found between the two groups. This fi nding suggests that the thickness of the IO muscle in the experimental group had a tendency to decrease, which in turn further supports the selective motor control of the core abdominal muscles. The thickness measurements ( cm ) of the TrA, IO and EO muscles in the experimental and control groups are shown in Figure

33 Table 2. Comparison of muscle thicknesses ( cm ) in TrA, IO, and EO between the experimental and control groups Experimental Control p-value Mean 95% difference a TrA 0.86 ± ± * 0.24 ( 0.08 to 0.40) b IO 0.79 ± ± ( 0.29 to 0.02) c EO 0.42 ± ± ( 0.09 to 0.09) The experimental group performed ADIM+irradiation whereas controls performed ADIM only. * Independent t-test revealed a significant difference between the two groups. a Transverse abdominis. b Internal oblique. c External oblique. Figure 2. Thickness ( cm ) of the transverse abdominal (TrA) muscle, internal oblique (IO) muscle and external oblique (EO) muscle in the experimental and control groups

34 2. Test-Retest Reliability The test retest reliability ICC (2, 1) revealed ICCs of 0.96 (95% CI 0.85 to 0.99), 0.87 (95% CI 0.62 to 0.98) and 0.77 (95% CI 0.44 to 0.96) for the TrA, IO and EO muscles, respectively. The Bland and Altman plots showed that the mean differences and the 95% limits of agreement in the TrA, IO and EO muscles were 0.24 cm ( 0.52 to 1.00 cm : Figure 3), 0.13 cm ( 0.87 to 0.60 cm : Figure 4) and 0.00 cm ( 0.45 to 0.44 cm : Figure 5), respectively

35 Figure 3. Bland and Altman plot showing the reliability of ultrasound image measurement for the thickness of the transverse abdominal (TrA) muscle imaged in two abdominal draw-in maneuver interventions. The middle line shows the mean difference. The 95% upper and lower limits of agreement represent 2 standard deviations above and below the mean difference

36 Figure 4. Bland and Altman plot showing the reliability of ultrasound image measurement for the thickness of the internal oblique (IO) muscle imaged in two abdominal draw-in maneuver interventions. The middle line shows the mean difference. The 95% upper and lower limits of agreement represent 2 standard deviations above and below the mean difference

37 Figure 5. Bland and Altman plot showing the reliability of ultrasound image measurement for the thickness of the external oblique (EO) muscle imaged in two abdominal draw-in maneuver interventions. The middle line shows the mean difference. The 95% upper and lower limits of agreement represent 2 standard deviations above and below the mean difference

38 3. Electromyographic Data A paired t-test showed a significant difference in EMG amplitude of the TrA/IO muscle between the ADIM alone and the ADIM in combination with ankle dorsiflexion, thus suggesting stronger activation during the latter than the former (Table 3). The sequential activation pattern of the TA, RF and TrA/IO muscles during ankle dorsiflexion is illustrated in Figure 1. Table 3. Comparison of deep abdominal muscle EMG amplitudes (root-mean-square, RMS) in the experimental group a ADIM ADIM + Irradiation p-value Mean 95% CI b TrA/IO ± ± < 0.01 * (53.16 to 84.36) * A paired t-test revealed a significant difference in the experimental group. a Abdominal draw-in maneuver. b Transverse abdominis/internal oblique

39 Discussion This study is the first to investigate the augmented effect of the ADIM and ankle dorsiflexion on selective motor control and muscle thickness in core muscles. As anticipated, the data show that a combination of the ADIM and ankle dorsiflexion is significantly more effective in improving selective motor recruitment and associated thickness of the TrA muscle than the ADIM alone. The US imaging data are consistent with previous findings investigating the effect of core stabilization on muscle thickness during the ADIM. The thickness of the TrA muscle during the ADIM was approximately 0.77 cm in a previous study (Critchley, and Coutts 2002), whereas in the present study, the thickness of the TrA muscle increased by approximately 0.86 cm during the combination of the ADIM and ankle dorsiflexion, and by 0.62 cm during the ADIM alone (39% increase). In contrast, the thickness of the IO and EO muscles tended to decrease during the combination of ADIM and ankle dorsiflexion, although the mean differences failed to reach statistical significance. These findings further indicate that ankle dorsiflexion in combination with the ADIM may have produced spatial and temporal summation, and selectively stimulated the deep target TrA muscle against the resistance, thus leading to augmented core stability or stiffness. The present EMG findings show that the amplitude of the root mean square EMG data during the ADIM in combination with ankle dorsiflexion ( mv ) increased

40 by approximately 200% compared with that of the ADIM alone (71.21 mv ). Recent research examining the relationship between muscle activity and the change in thickness of the TrA muscle during the ADIM using fine-wire EMG and US imaging reported a similarly strong correlation (R²=0.87, p<0.01) (McMeeken et al. 2004). Neurophysiologically, it can be extrapolated that such augmented and selective improvement in muscle activity may have been the result of energy overflow or propagation from the TA (distal) muscle to the TrA/IO (central) muscle via a long and elastic anterior fascia connection (Buchwald 1967; Hopf, Schlegel, and Lowitzsch 1974; Moore 1975) when ankle dorsiflexion was added to the ADIM, which was observed in a sequential EMG activation pattern. In fact, there is a growing body of evidence to show that core stability can be further strengthened when the central core exercise is combined with distal upper or lower extremity exercises (i.e. dead bug, one-leg bridging and stability ball bridging) (Hodges 2001; Hodges, Cresswell, and Thorstensson 1999; Hodges, and Richardson 1997; Moseley, Hodges, and Gandevia 2002). Certainly, these results have important clinical implications, as they show that ADIM training is beneficial for selective recruitment of the TrA muscle and its central mechanism of action on the lumbopelvic region, and that the mechanism of a deep musculofascial corset can be further augmented by ankle dorsiflexion. Previous evidence on the clinical management of LBP suggests that support and protection of the spine is essential to stiffen the lumbosacroiliac joints during selective core

41 stabilization training of the TrA muscle, thereby minimizing clinical complaints about LBP and lumbar spinal instability (Hides et al. 2006). When considering the ICCs, the test retest reliability data demonstrate excellent results, suggesting a good degree of repeatability between the repeated US measurements. However, the Bland and Altman limits of agreement are wider than the differences found between groups, which suggests that the measurements may be subject to consequential error. Previous studies have reported a relatively poor degree of reliability (Critchley, and Coutts 2002; Hides et al. 2007; Hodges et al. 2003; O Sullivan et al. 1997), although the reliability in this study may have been improved by the use of a transparent sheet and static position measurement which attempted to control for error associated with the inconsistent location of US applications and movement artifacts, where other studies have used washable skin markers and dynamic conditions. It is tentatively suggested that abdominal muscle thickness measurements obtained by US image can be reasonably accurate and reliable, within the limits defined by the Bland and Altman analysis. With further refinement, these measurements may provide a good measure for the assessment of intervention-related morphological changes and associated motor control mechanisms. Several shortcomings were identified in this research, which could be considered to enhance a more robust and large-scale clinical study in the future. First, this research represents a preliminary experiment intended to investigate the immediate effect of the ADIM in combination with ankle dorsiflexion in healthy subjects. Therefore, it invites future research that examines the long-term effect of the

42 intervention in both normal and pathological populations, such as those suffering from LBP. Second, the mechanism of action in the deep multifidus muscles, which is synchronously orchestrated in harmony with the deep abdominal muscles, the TrA, for core stability, was not measured. It would be of great interest to probe the mechanism of action in these muscles (MacDonald, Moseley, and Hodges 2006). Finally, the results of this study cannot be generalized because the sample was limited to young, healthy adults. Thus, at this time, the technique discussed here cannot be said to provide an optimal strategy for training TrA muscle control. Nevertheless, the findings on the core technique make an important contribution to the existing body of knowledge on the therapeutic exercise of abdominal muscles in patients with acute LBP for whom the current ADIM is not easily applicable due to their severe impairments such as pain and weakness

43 Chapter Ⅲ Use of Co-contraction of Ankle Dorsiflexors to Increase Transverse Abdominis Function in Low Back Pain (Experimental Study 2) Introduction Mechanical low back pain (LBP) is a common musculoskeletal impairment. It is often associated with transverse abdominis (TrA) neuromuscular dysfunction and spinal instability, thereby affecting ADLs and physical activity (Cairns, Foster, and Wright 2006; Hides et al. 2006; Standaert, and Herring 2007). Epidemiological evidence indicates that up to 70% of patients with acute LBP ultimately progress to chronic LBP (Pengel et al. 2003). Delayed onset time of TrA feedforward activation during shoulder movement (Hodges, and Richardson 1996) and altered muscle activation patterns during locomotion (Hall et al. 2009) have been identified in LBP

44 patients as important pathological markers of abdominal neuromuscular dysfunction. Normally, the neuromuscular system is believed to maintain lumbar spinal stability by increasing the stiffness (both active and passive) of the deep abdominal and multifidus muscles or modulating muscle co-contraction, which increases the compressive loads (Vera-Garcia et al. 2007). This lumbar spinal stability offsets the deleterious effects of stress imposed on the spine during lifting (Butler, Hubley- Kozey, and Kozey 2007; O Sullivan et al. 1997; Stanton, and Kawchuk 2008). Core stabilization exercises including ADIM, lateral bridging, pelvic tilting, and abdominal bracing (Akuthota, and Nadler 2004; Kavcic, Grenier, and McGill 2004; Standaert, and Herring 2007) have been widely used to improve lumbopelvic stability (Hodges, and Richardson 1996; McGill 1997). Core stabilization exercises often incorporate a low degree of TrA activation loading (less than 30% maximal voluntary isometric contraction (MVIC) with minimal activity of superficial muscles such as external oblique (EO) and rectus abdominis during the initial phase of rehabilitation (Butler, Hubley-Kozey, and Kozey 2007; Ferreira, Ferreira, and Hodges 2004). One important mechanism by which core stabilization exercise increases the neuromuscular function of the TrA and associated lumbar spinal stability is the neuromechanic stiffening of the thoracolumbar fascia (TLF) (Stanton, and Kawchuk 2008). Specifically, the synergistic contraction of the TrA and posterior fibers of the internal oblique (IO) increases the posterior-lateral lumbar tension on the TLF that connects to both the spinous and transverse processes of the lumbar spine (Stanton, and Kawchuk 2008). When the ADIM is performed, the activated TrA draws the

45 abdominal wall inward while concurrently forcing the viscera upward into the diaphragm and downward into the pelvic floor. Co-activation of the TrA and IO together with the TLF generates intra-abdominal pressure, which transforms the abdomen into a mechanically rigid cylinder, thereby providing spinal stability (Nordin, and Frankel 2001). Administering core stabilization exercises to LBP patients with severe pain may result in a substitution or compensatory movement (e.g., rotation and extension of the lumbopelvic complex) associated with neuromuscular inefficiency in the deep core muscles. Therefore, it has been suggested that abdominal or core stabilization exercise without proper pelvic stabilization may increase intradiscal pressure, anterior shearing, and compressive forces in the lumbar spine, thereby accentuating LBP (Hodges, and Richardson 1996; McGill 1997). A method to enhance the activation of the deep abdominal muscles may be advantageous. Resisted ankle dorsiflexion to augment the TrA/IO via co-contraction is a technique for improving the selective activation of deep core muscles such as TrA/IO in pain-free populations (Chon, Chang, and You 2010). This approach was derived from the concept of irradiation in the proprioceptive neuromuscular facilitation (PNF), which emphasizes the important contribution of the relatively stronger distal muscle group by increasing the number of potential motor unit recruitments involved or weakened. A recent study demonstrated that the co-activation of the ankle dorsiflexors and rectus femoris (RF) muscles effectively augmented the selective activation of TrA muscle as evidenced by an increased mean EMG amplitude of the

46 TrA/IO muscles after the resisted ankle dorsiflexion (Chon, Chang, and You 2010). EMG analysis showed that a strong contraction of the dorsiflexion muscles, specifically the tibialis anterior (TA) improved motor recruitment of the TrA/IO muscles during the ADIM (Chon, Chang, and You 2010). This finding suggests that co-contraction of the dorsiflexion muscles increases the recruitment of the active motor units of TrA/IO muscles (Chon, Chang, and You 2010; Eccles, and Sherrington 1930; Hall et al. 2009). In fact, enhanced TrA neuromuscular control patterns in individuals with LBP were found to play an important role in functional spinal mobility and back pain (O Sullivan et al. 1997; Teyhen et al. 2005; Torres- Oviedo, Macpherson, and Ting 2006). While there is evidence that core stabilization exercises can contribute to deep abdominal contraction (O Sullivan et al. 1997), there is a dearth of information on effective ways to improve TrA muscle activation and timing in the LBP population. Hence, the purpose of this study was to determine the effect of two weeks of ADIM and co-contraction training on abdominal muscle thickness and activation timing, as well as to monitor pain and function in subjects with LBP

47 Method 1. Participants This study was a case control study with an experimenter-blind design. A convenience sample of 40 participants volunteered for this study. Among them, twenty patients with LBP (age=27.20 ± 6.46 years, height= ± 8.70 cm, mass=58.10 ± kg ) were recruited from a local orthopedic clinic and 20 healthy controls (age=24.25 ± 1.59 years, height= ± 8.89 cm, mass=60.65 ± kg ) from a university community. The independent t-test revealed no significant differences in age (p=0.06), height (p=0.51), or weight (p=0.50), which confirms the similar demographic characteristics of the two groups (Table 4). Figure 6 presents the Consolidated Standards for Reporting of Trials (CONSORT) chart. All of the participants read and signed an informed consent that was approved by the university ethics and institutional review board. Data collected pertinent to the LBP patients included onset time, nature and location of symptoms, aggravating and relieving factors, medication, surgical history, previous back pain or injury, and pain measurements. The inclusion criteria for the LBP group were: (1) clinical assessment of mechanical LBP. (2) presence of periods of LBP within the past six to 12 months. (3) a current pain level ranging from 4/10 to 8/10 on the self-reported visual analog scale (VAS). Patients with LBP who had previously received conservative therapy

48 (i.e., hydrocollator, ultrasound, TENS, interferential current therapy, ROM, and the William flexion exercises), but with limited therapeutic effects, were observed. None of the participants had prior knowledge or experience of ADIM training. The clinical assessment criteria for mechanical LBP were: (1) intermittent pain during the day that gradually develops later in the day. (2) pain when standing or sitting for a long time. (3) pain upon trunk flexion (or occasionally extension) (Brown, and Snyder-Mackler 1999; Walker, and Williamson 2009). (4) pain when driving long distances or getting in and out of a car. An experienced physical therapist (10 years) made the diagnosis of mechanical LBP according to the clinical assessment criteria. Medical diagnosis of LBP was made by an attending orthopedist or a physician. The exclusion criteria included osteoporosis, structural deformity, systemic inflammatory disease, nerve root compression, facet osteophytes, prolonged severe pain, neuro-musculoskeletal system problems, and previous spinal surgery. These exclusion criteria were confirmed by reviewing each patient s medical chart reported by the physician. The control group comprised healthy young adults with no known medical problems or a history of LBP. All assessments were made by researchers who were blinded to the clinical status (healthy or LBP) and all measurements. Both the healthy and LBP groups underwent a pretest, followed by a 5 days a week training program (co-contraction treatment) for 2-weeks and a posttest after the training (Figure 6). The dependent variables measured included the VAS, the pain disability index (PDI), and the pain rating scale (PRS), muscle thickness for TrA, IO, EO, EMG mean and peak amplitudes, onset

49 time, and latency for TrA/IO, TA, and RF. Table 4. The demographic and clinical characteristics of subjects Variable LBP Group (n 1 =20) Healthy Group (n 2 =20) p-value Age (years) ± 6.46 a ± Height ( cm ) ± ± Weight ( kg ) ± ± Gender Male / Female 7 / 13 9 / 11 Onset duration (month) 15.3 ± 9.03 NA b VAS c (0-10 score) 6 / 10 NA PDI d (0-70 score) 30 / 70 NA PRS e (0-130 score) 70 / 130 NA a Mean ± SD. b Non application. c Visual analogue scale. d Pain disability index. e Pain rating scale

50 Figure 6. Flow diagram for this study

51 2. Intervention Both the healthy and LBP groups received a combination of US and EMG-guided visual biofeedback for 30 minutes a day, five days a week over a two-week period. Determination of the outcomes and performance of the ADIM and co-contraction to augment TrA/IO was made using visual and tactile feedback. As illustrated in Figures 7 and 8, visual feedback information about EMG co-contraction and change in muscle thickness were presented in the respective EMG and US computer monitors and used for augmented feedback during ADIM and co-contraction training. Proper electrode placement for TrA/IO was ensured with US imaging, which was used to identify the proper location of these muscles during ADIM. For the ADIM training, each participant was instructed to lie in a hook-lying position. A pressure biofeedback unit was placed underneath the fifth lumbar vertebra and inflated to mm Hg (Hodges, Richardson, and Jull 1996; Roussel et al. 2009). The participant was then asked to draw in his or her navel gradually and maintain the target pressure without any pelvic motion. For ADIM and added cocontraction training, the participant was first asked to perform ADIM and co-contract the TA and RF muscles against static resistance (with 50% MVIC of the TA), which was induced by a fixed-strap band. If the participant correctly performed ADIM and co-contraction training without pelvic rotation or compensatory upper chest elevation with overexertion, the training was considered successful. The proper performance

52 of ADIM and co-contraction was confirmed by visual inspection and concurrent US and EMG measurements, which were used to carefully monitor changes in TrA/IO muscle thickness and activity sequence. Additional tactile feedback was provided if necessary. Figure 7. EMG biofeedback during the resisted dorsiflexion training to augment transverse abdominis (TrA) muscle contraction. EMG biofeedback was used to provide visual feedback about muscle activation of the corresponding TrA/internal oblique (IO), tibialis anterior (TA), rectus femoris (RF), and TrA/IO in sequence. The vertical arrow indicate the time at which automatic auditory cue from EMG software was sequentially given for initial TrA/IO contraction, co-contraction of TA- RF-augmented TrA/IO muscles, and release (or rest)

53 Figure 8. Participant positioning during co-contraction biofeedback training

54 3. Pain and Function Assessment Standardized pain and associated functional activity-based pain measurements included the VAS, PDI, and PRS for the LBP group only. The VAS incorporates a 10-cm straight line on which the participant scores his or her pain on a scale that ranges from 0 ( no pain ) to 10 ( pain as bad as it could be ) (Jensen, Chen, and Brugger 2002; Love, Leboeuf, and Crisp 1989). The test-retest reliability of this scale ranges from 0.60 to 0.77, and its validity from 0.64 to 0.84 (Boonstra et al. 2008). The PDI is a brief self-report instrument that provides information that complements the evaluation of physical functional impairment. It comprises seven sub-items of physical activities: recreation, occupation, sexual behavior, family and home duties, social functions, self-care, and life-support functions (Grönblad et al. 1993; Tait, and Chibnall 2005). The scoring system allows the patient to rate these activities on a scale that ranges from 0 to 10, with a total possible score of 70 (Tait, and Chibnall 2005). The test-retest reliability of the PDI ranges from 0.73 to 0.91 (Grönblad et al. 1993). The PRS includes the three separate clinical illness components that constitute LBP in point scales: back and leg pain (0-60 points), disability index (0-30 points), and physical impairment (0-40 points) (Childs, Piva, and Fritz 2005; Manniche et al. 1994). The scale was designed to monitor outcomes following therapeutic intervention. The higher the score, the greater the level of disability and impairment, with a maximum point value of 130. The intra-class correlation coefficient (ICC) of the PRS is a 0.61 (Childs, Piva, and Fritz 2005), with a high level of inter-rater

55 reliability (97.7%) (Manniche et al. 1994)

56 4. Ultrasound Imaging Measurement A Logiq US imaging system (α 200, Samsung-GE Medical Systems Inc., Seongnam, South Korea) with a 7.5-MHz linear transducer was used to assess muscle thickness during the test. The thickness of the abdominal wall muscles, including the TrA, IO and EO muscles, were measured, and changes in the TrA was calculated. Muscle thickness was an indicator of muscle function or activity. The change in TrA thickness represents the relative changes in the thickness of the TrA contracted to TrA rest, which typically involves examination of the relative change in TrA muscle thickness (Mannion et al. 2008). Participants were asked to assume a relaxed hooklying position (Hodges, and Richardson 1996). Their hip and knee joint angles were maintained at approximately to eliminate lumbar lordosis. The inferior borders of the rib cage and iliac crest on the dominant side were palpated as reference points (Whittaker 2008). US gel (AQUASONIC 100, Parker Inc., Orange, NJ) was then applied to the transducer head, which was transversely positioned 25 mm anteromedial to the midway point between the 12 th rib and the iliac crest (Figure 9) (McMeeken et al. 2004; Whittaker 2008). The transducer head was maneuvered until the sharpest images of all of the lateral abdominal muscles (EO, IO, and TrA) had been obtained (Teyhen et al. 2005). Three scans were taken on the dominant side of the abdominal muscles in their relaxed state (Teyhen et al. 2005). The dominant side of the normal controls was determined by asking them to kick a ball, whereas the

57 dominant side of the patients with LBP was determined by asking them which was the more painful side. The pretest scanning location was marked on a transparent sheet to ensure identical placement throughout the experiment, including the posttest (Rankin, and Stokes 1998). Specifically, the anatomical reference locations for the iliac crest and the 12 th rib were first palpated to identify and mark their locations with a permanent marker. We then superimposed the transparent sheet over these locations and made corresponding markings on it with the permanent marker for consistent measure (Figure 9). The images were acquired at the end of the exhalation phase (Whittaker 2008). The image data were stored, and the measurements of the muscle thickness dimension ( mm ) were determined with an on-screen caliper. The thicknesses of all three muscles were defined by drawing a vertical reference line that was located 25 mm from the left edge (muscle-fascia junction) of the TrA (Figure 10) (Whittaker 2008). Based on this protocol, we conducted a test-retest reliability study to determine the degree of reliability between our pre- and posttest use of the US measurements of abdominal muscle thickness in LBP patients, including those of the TrA, IO, and EO muscles

58 Figure 9. Placement of ultrasound transducer on abdominal muscle. Figure 10. Abdominal muscle thickness measurement

59 5. Electromyographic Measurement Each subject s skin preparation was carefully implemented to reduce skin impedance to below 5 kω by dry-shaving hair with a disposable razor, abrading the skin with fine sandpaper, and cleansing it with a 2% alcohol swab. Once the skin was dry, pairs of circular Ag/AgCl surface electrodes with a contact diameter of 19 mm were attached at an interelectrode distance of 20 mm to the following locations (Figure 11). A reference electrode was positioned over the lateral malleolus. The electrode placement for the TrA/IO was approximately 20 mm medial and inferior to the anterior superior iliac spine (ASIS) (Marshall, and Murphy 2003). For the TA it was 20 mm distal and lateral from the tibial tubercle, and for the RF it was halfway between the ASIS and the superior part of the patella (Figure 11) (Cram, and Kasman 1998). A surface EMG system (WEMG-8 System, Laxtha Inc., Daejeon, South Korea) is composed of 8 electrodes, a preamplifier for initial processing, a second amplifier, an A/D converter of 16-bit resolution, a USB connection, and a WEMG-8-type cable. This EMG was used to record the onset times and mean and peak amplitudes of the TA, RF, and TrA/IO muscles. These EMG data were used to provide proper muscle activation sequence during the co-contraction training. Because approximately 30% MVIC has been reported to be the best activation level for the TrA/IO muscles (Butler, Hubley-Kozey, and Kozey 2007), we used this

60 criterion during our EMG biofeedback training for effective co-contraction of the target muscles. Once the MVIC for each TA, RF, and TrA/IO muscle was reached, participants were instructed to sustain 30% MVIC of the TrA/IO (Butler, Hubley- Kozey, and Kozey 2007), followed by 50% MVIC of the TA, RF, and TrA/IO during co-contraction training for 3 seconds, and then to rest for 5 seconds. EMG monitoring was used to ensure consistent muscle activation at each target MVIC for the corresponding muscle. An automatic auditory cue that lasted for 3 seconds over a 20 seconds period was provided for each participant to start contracting the muscle at the proper time interval (Figure 7). The raw EMG signal was processed using Telescan 2.89 software (WEMG-8 System, Laxtha Inc., Daejeon, South Korea) at a sampling frequency of 1024 Hz with a 60-Hz notch filter for noise reduction associated with electrical interference arising from the usual sources including 60 Hz power lines or radio frequencies, and electric or magnetic devices. The root mean-square EMG amplitude for each TA, RF, and TrA/IO muscle was calculated for 3 seconds (3-6 seconds duration) during the ADIM and for 3 seconds (12-15 seconds) during the co-contraction (Figure 7). The identification of the onset time of EMG for each TrA/IO, TA, and RF muscle was determined as the onset point at which the mean of 51.2 consecutive samples (50 ms ) exceeded the baseline activity (threshold level) by three standard deviations. The raw EMG signal was full-wave rectified and filtered using a band pass filter at Hz, with a rejection factor of -3 db. Baseline activity was defined as a period of

61 approximately 3 seconds before ADIM movement or 6 seconds before ankle dorsiflexion. Each onset time was visually checked to ensure that EMG onset was misrepresented or cofounded by motion artifact or environmental interference. Less than 5% of all trials were discarded following visual inspection due to an inability to differentiate the muscle onset from environment interference or activity. The latency between the onset of the TrA/IO and the TA muscles, and the TA and the RF, as well as the TrA/IO and the RF muscles, was analyzed for both groups. EMG data for pre-/post-test were not recorded. Initially, we intended to use EMG primarily to provide visual biofeedback and monitor consistent mean and peak amplitudes and sequences for the TrA/IO, RF, and TA to maximize our ADIM training effect during the co-contraction training. EMG activity was recorded in 2 sessions in the first week of the training and another 2 sessions in the second week to facilitate a proper sequence of muscle activation

62 Figure 11. Placement of EMG electrodes

63 6. Statistical Analysis Standard statistical analysis included computations of means and standard deviations, a mixed 2 2 analysis of variance (ANOVA), paired two-tailed t-test, ICC, and standard error of the measurement (SEM). The independent variables included group and time factors. The dependent variables included VAS, PDI, PRS, muscle thickness, EMG peak and mean amplitude, onset time, and latency. Three separate 2 (group) 2 (time) mixed-model ANOVAs were performed to evaluate the effect of co-contraction training on increasing TrA muscle thickness using the resisted ankle dorsiflexion technique, with time (or intervention) as a within-subject factor and two independent groups as a between-group factor. Post-hoc comparison using Tukey s honestly significant difference (HSD) test was performed if significant interactions were obtained. The independent t-tests were used to determine differences in muscle rest thickness and muscle contraction thickness for TrA, IO, and EO between groups at the pretest. Additional analysis was implemented using the independent t-test to assess the differences in mean and peak EMG amplitudes, onset time, and latency between the healthy and LBP groups. The paired t-test was also used to assess the differences in mean and peak EMG amplitudes between baseline TrA/IO and co-contracted TrA/IO. Pre-post differences in the VAS, PDI, and PRS were used to assess pain in the LBP group using the paired t-test. Significance level was set at p<0.05 for all analyses

64 ICC analysis was used to examine the test-retest reliability of the US measurements of abdominal muscle thickness (Bland, and Altman 1986). ICC (3, 1) (two-way mixed, single measure) was performed at a 95% confidence interval (CI) of the difference between the repeated US measurements of muscle thickness at two separate occasions (48-72 hours apart) (Hopkins 2000; Shrout, and Fleiss 1979). The SEM was defined as SEM=standard deviation (SD) (1-ICC) 0.5, where SD is the 1 SD of all measurements. SPSS for Windows statistical software (SPSS release 12.0, SPSS Inc., Chicago, IL, USA) was used, with statistical significance set at p<

65 Results 1. Clinical Data Separate paired t-tests showed a statistically significant difference in the pain measurements, the VAS (p<0.01), PDI (p<0.01), and PRS (p=0.02), between the pre- and posttests in the LBP group (Table 5). Table 5. Comparison of pain data obtained from VAS, PDI, and PRS measures between the pre-/post-intervention in the LBP group (n=40) Pretest Posttest Mean difference 95% CI p-value VAS b a ( -2.15, -0.85) 0.00 PDI c ( -9.63, -4.47) 0.00 PRS d (-10.07, -5.93) 0.02 a Mean ± SD. b Visual analogue scale. c Pain disability index. d Pain rating scale

66 2. Ultrasound Imaging Data A separate mixed 2 2 ANOVA showed a significant group intervention interaction and intervention main effect for the TrA muscle contraction thickness (p=0.01), but this was not the case for IO (p=0.83) and EO (p=0.53) (Table 6). Further analyses using Tukey post hoc tests showed that the LBP group significantly improved on muscle contraction thickness after the training compared to the healthy group. No significant between group effects were observed. Independent t-tests showed significant differences in baseline (rest) muscle thickness for TrA (p<0.01), IO (p=0.02), and EO (p=0.00) between groups at the pretest, but no significant changes in muscle contraction thickness were observed (Table 7)

67 Table 6. Comparison of the abdominal muscle contraction thickness ( mm ) between groups LBP Group (n 1 =20) Healthy Group (n 2 =20) Pretest Posttest Pretest Posttest p-value TrA b a IO c EO d a Mean SD. b Transverse abdominis. c Internal oblique. d External oblique. A significant group intervention interaction and intervention main effects were observed only for TrA muscle contraction thickness (p<0.05), but did neither IO nor EO show any interaction effects. Tukey HSD confirmed that the LBP group showed greater improvement in TrA muscle contraction thickness as compared with the healthy group at the posttest. No between-group effect was obtained

68 Table 7. Comparison of baseline muscle rest thickness ( mm ) and muscle contraction thickness of the abdominal muscles between groups at the pretest LBP Group (n 1 =20) Healthy Group (n 2 =20) p-value Rest TrA b a IO c EO d Contraction TrA IO EO a Mean SD. b Transverse abdominis. c Internal oblique. d External oblique. Independent t-test showed significant difference in baseline (rest) muscle thickness for TrA, IO, and EO between groups at the pre-test, but no significant changes in muscle contraction thickness were observed

69 3. Test-Retest Reliability The test-retest reliability (ICC (3, 1), 95% CI, SEM) analysis revealed ICCs of 0.99 (0.98 to 0.10, 0.02), 0.95 (0.82 to 0.99, 0.06), and 0.96 (0.85 to 0.99, 0.03) for the TrA, IO, and EO muscles, respectively

70 4. Electromyographic Data The independent t-test showed significant differences in the mean peak EMG amplitudes for TrA/IO (p=0.00), TA (p=0.00), and RF (p=0.00), but not for the cocontracted TrA/IO (p=0.07) between the healthy and LBP groups (Table 8). Significant differences in the mean EMG amplitudes were observed for TrA/IO (p=0.00), TA (p=0.00), and RF (p=0.00), but not for the co-contracted TrA/IO (p=0.08) between the healthy and LBP groups (Table 8). Significant differences in the mean onset time were observed for the TrA/IO (p=0.01) and TA (p=0.01), but not for the RF (p=0.11) between the healthy and LBP groups (Table 8). No significant difference in the mean latencies for TrA/IO-TA (p=0.48), TA-RF (p=0.14), and TrA/IO-RF (p=0.06) were found between the groups (Table 9)

71 Table 8. EMG peak amplitude, mean amplitude, and onset time data (root-meansquare, RMS) between groups during the co-contraction training LBP Group (n 1 =20) Healthy Group (n 2 =20) p-value TrA/IO b Peak amplitude ( μv ) a Mean amplitude ( μv ) Onset time (s) TA c Peak amplitude ( μv ) Mean amplitude ( μv ) Onset time (s) RF d Peak amplitude ( μv ) Mean amplitude ( μv ) Onset time (s) Co-contracted TrA/IO Peak amplitude ( μv ) * * 0.07 Mean amplitude ( μv ) * * 0.08 Onset time (s) NA e NA a Mean SD. b Transverse abdominis/internal oblique. c Tibialis anterior. d Rectus femoris. e Not applicable. * Paired t-test showed statistical significance between TrA/IO and co-contracted TrA/IO (p<0.05). Note that TA and RF muscles were co-contracted, followed by the initial onset of TrA/IO muscle activation. Onset time for the co-contracted TrA/IO was not determined due to additive contraction

72 Table 9. Mean EMG latency between groups during the co-contraction training Latency (sec) LBP Group (n 1 =20) Healthy Group (n 2 =20) p-value TrA/IO b TA c a TA RF d TrA/IO RF a Mean SD. b Transverse abdominis/internal oblique. c Tibialis anterior. d Rectus femoris

73 Discussion This study presents clinical evidence that demonstrates the potential efficacy of the combined co-contraction and ADIM technique for sequential motor recruitment and muscle thickness in the abdominal muscles of healthy adults and those with chronic LBP. Our data show that treatment with the combined technique (co-contraction) was effective in the LBP group in increasing TrA muscle thickness. Our findings suggest that the ADIM followed by co-contraction technique is useful in stimulating the selective recruitment of the TrA. Previously, the co-contraction technique had only been studied in normal subjects rather than a pathological group (Chon, Chang, and You 2010). We used US imaging to determine a subject s ability to activate or contract the TrA using changes in the muscle thickness. McKeeken et al. (2004) investigated the relationship between muscle activity and thickness changes of the TrA during the ADIM using fine-wire EMG and US imaging techniques and reported a strong correlation of the two measures (R 2 =0.87, p<0.01). Our US imaging data are consistent with the findings of a previous study investigating the effect of core stabilization on muscle thickness during ADIM combined with resisted ankle dorsiflexion treatment (Chon, Chang, and You 2010). In the present study, the TrA muscle thickness increased by approximately 31% (from 3.5 mm to 4.6 mm ) while the TrA muscle contraction thickness increased 13% (from 12 to 13.6) for the LBP

74 patients. The TrA muscle thickness increased 6% (from 8.1 mm to 8.6 mm ) while the muscle contraction thickness increased 3% (from 14.7 to 15.1) for the healthy controls. Independent t-tests showed significant differences in baseline (rest) muscle thickness for TrA, IO, and EO between groups at the pretest, but no significant changes in muscle contraction thickness were observed. The pretest differences in baseline (rest) muscle thickness between the groups imply a pathological condition, either atrophy or a neuromuscular inhibition in the abdominal muscles of patients with LBP. However, increased activation of the previously inhibited TrA after training suggests the positive benefits of ADIM and the co-contraction technique in patients with LBP (Cairns, Foster, and Wright 2006; Hodges, and Richardson 1996; Kumar, Sharma, and Negi 2009; O Sullivan et al. 1997). Moreover, the additive effect of co-contraction to ADIM training seems to be more advantageous for LBP patient population than for the healthy controls. As shown in Figure 7, the second TrA/IO EMG peak amplitude was amplified after the co-contraction was applied. This finding suggests that the co-contraction was associated with improvements in the TrA activation, supporting a potential therapeutic efficacy of this novel technique. Previous studies showed that increases in TrA muscle thickness were associated with improved lumbar stiffness or spinal stability, contributing to pain reduction in individuals with LBP (Chon, Chang, and You 2010; O Sullivan et al. 1997). Previous studies proposed that the recurrence of LBP is associated with a delayed timing dysfunction of the TrA (Butler, Hubley-Kozey, and Kozey 2007; Ferreira, Ferreira, and Hodges 2004; Hall et al. 2009; Hodges 2001). Our EMG onset time data

75 confirmed that initial TrA/IO, TA, and RF onset times in the LBP group were significantly slower than those in the healthy group. Similarly, LBP patients had delayed EMG latency. The mean EMG amplitudes of the LBP patients were smaller than those of the healthy controls. These findings suggest that LBP patients had altered motor activation patterns compared to those of normal controls. This altered neuromuscular response has been identified as an important marker or a pathological characteristic associated with mechanical LBP (Hall et al. 2009; Hodges 2001; Hodges, and Richardson 1996; Roussel et al. 2009). However, this assumption needs to be validated. In our study, after co-contraction with ADIM, the impaired neuromuscular responses (peak amplitude and mean amplitude) improved more in the co-contracted TrA/IO than in the initial TrA/IO, suggesting that the co-contraction may be useful in treating activation timing factors. Our findings are consistent with those of previous studies that demonstrated increased EMG amplitude following cocontraction training (Chon, Chang, and You 2010; Hall et al. 2009). Neurophysiologically, co-contraction involves motor synergies or coordinative structures whereby groups of muscles are recruited to work together as a functional unit (Torres-Oviedo, Macpherson, and Ting 2006). Hence, a facilitation of the impaired TrA function in LBP patients can be achieved by integrating the TA, quadriceps, and abdominal groups to work together as a functional core. When cocontraction was added to the ADIM, as observed by the improved sequencing of the EMG activation pattern during the co-contraction training, the lumbopelvic unit was trained to demonstrate a motor pattern more similar to healthy individuals. Previous

76 studies demonstrated that a combination of the isolated training of delayed TrA activation and non-isolated functional training (involving abdominal curl ups, side bridges, and birddogs) was beneficial for pain and functional improvement in LBP patients (O Sullivan et al. 1997; Stuge et al. 2004). One study found that delayed feedforward activation of the medial quadriceps muscle in individuals with patellofemoral pain was enhanced with comprehensive isolated and non-isolated contraction training (Cowan et al. 2003). A combination of isolated training (initial ADIM of delayed TrA/IO) and non-isolated training involving co-contraction of the TA and RF helped to restore delayed TrA activation, which is a consistent promarker of abdominal neuromuscular dysfunction in LBP. Hence, earlier activation of the TrA during the co-contraction training as reflected in our EMG onset time data can be considered an important indicator of improved neuromuscular control. This improved neuromuscular response has greater force-generating potential and an enhanced ability to increase spinal stiffness, resulting improvements in pain, function, and recurrence rates in LBP patients (Cholewicki, and McGill 1996; Kavcic, Grenier, and McGill 2004; O Sullivan et al. 1997). Perhaps EMG could be used to provide accurate information about motor activation pattern and sequence. The LBP group targeted potential subjects with recurrent mechanical back pain who had failed previous conservative treatments. In those subjects, we observed a reduction of pain and improvement in function in LBP subjects, specifically with significant improvements in VAS, PDI, and PRS following the intervention. Our findings are consistent with O Sullivan et al. (1997) who showed that engaging in

77 ADIM exercise for 15 minutes a day for 10 weeks significantly reduced the VAS scores of patients with spondylolysis or spondylolisthesis from 6 to 2. Kumar et al. (2009) reported that the administration of the ADIM in combination with various core exercise for 5 weeks in patients with chronic LBP resulted from 7 to 1 on the VAS. The results of the present study have a number of important clinical implications. They show that ADIM training is beneficial for the selective recruitment of the TrA and its central mechanism of action on the lumbopelvic region, and that the mechanism of the deep musculofascial corset may be further augmented by the cocontraction technique. Previous evidence of the clinical management of LBP suggests that the support and protection of the spine is essential to stiffening the lumbosacroiliac joints during selective core stabilization training of the TrA, thereby minimizing clinical complaints of LBP and lumbar spinal instability (Hides et al. 2006). Our test-retest reliability data suggest a good degree of reliability in our repeated US measurements, which is in contrast to a number of earlier studies that reported a relatively poor degree of reliability (Hodges et al. 2003; Mannion et al. 2008). Others have demonstrated a good to high degree of reliability (Hebert et al. 2009; Hides et al. 2007; McMeeken et al. 2004). Our higher degree of test-retest reliability may be due to our consistent use of a transparent sheet and static position measurement to control for potential errors associated with the inconsistent location of US applications and movement artifacts. Our findings corroborate existing evidence showing that the

78 abdominal thickness measurements obtained from US imaging are accurate and reliable. Hence, such measurements are a good indicator of intervention-related morphological changes and associated motor control mechanisms. Notwithstanding its significant results, this study had several shortcomings that should be addressed in a more robust and large-scale clinical study. First, it is possible that US-guided visual feedback at pretest may have affected outcome results in muscle thickness measures. Hence, in future visual feedback should be excluded in the pretest. Second, the ephemeral changes in muscle thickness are unlikely to occur within such a short duration of strength training. The motor learning literature has shown that corticospinal excitability occurs within the first 2 weeks of training when the main improvement in motor performance is achieved, and reaches a significant level after 4 weeks of training (Abe et al. 2000; Jensen, Marstrand, and Nielsen 2005; Legg 1981; MacDougall et al. 1995). The long-term effect of such intervention needs further exploration. Third, the function of the multifidus, which provides segmental stability, was not measured. It would be of great interest to further probe the mechanism of action in these muscles (MacDonald, Moseley, and Hodges 2006). Lastly, the results of this study cannot be generalized due to limited sample size and our case control study design. A larger clinical trial with a true control group with LBP is needed to investigate the therapeutic effects of the resisted dorsiflexion contraction training to augment TrA/IO in clinical practice

79 Chapter IV Conclusion This series of two studies were designed to examine the effect of new method of ADIM combined with resisted ankle dorsiflexion training on the deep abdominal muscle in healthy adults and patients with LBP. Experimental study 1 provided empirical evidence to show that the ADIM combined with ankle dorsiflexion is useful in enhancing muscle activity and associated morphological changes in the TrA muscle. It offers clinical insights into the additive effect of ankle dorsiflexion in selectively stimulating the TrA muscle, and suggests that it may be used as an alternative core stabilization technique for the management of patients with LBP. Experimental study 2 highlighted the potential application of ADIM along with ankle dorsiflexion in normal and LBP groups. We demonstrated increased muscle thickness and the associated reduction of LBP after the intervention. The additive ADIM combined with ankle dorsiflexion training could be integrated as a part of a core stabilization regimen for the management of patients with LBP, but further study is needed to validate its therapeutic efficacy

80 References Abe T, DeHoyos DV, Pollock ML, and Garzarella L. Time course for strength and muscle thickness changes following upper and lower body resistance training in men and women. Eur J Appl Physiol. 2000;81(3): Adler SS, Beckers D, and Buck M. PNF in Practice: An illustrated guide. 3rd ed. Berlin: Springer, Akuthota V, and Nadler SF. Core strengthening. Arch Phys Med Rehabil. 2004;85(3 Suppl 1):S Bland JM, and Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet. 1986;1(8476): Boonstra AM, Schiphorst Preuper HR, Reneman MF, Posthumus JB, and Stewart RE. Reliability and validity of the visual analogue scale for disability in patients with chronic musculoskeletal pain. Int J Rehabil Res. 2008;31(2): Brown A, and Snyder-Mackler L. Diagnosis of mechanical low back pain in a laborer. J Orthop Sports Phys Ther. 1999;29(9):

81 Buchwald JS. Exteroceptive reflexes and movement. Am J Phys Med. 1967;46(1): Butler HL, Hubley-Kozey CL, and Kozey JW. Changes in trunk muscle activation and lumbar-pelvic position associated with abdominal hollowing and reach during a simulated manual material handling task. Ergonomics. 2007;50(3): Cairns MC, Foster NE, and Wright C. Randomized controlled trial of specific spinal stabilization exercises and conventional physiotherapy for recurrent low back pain. Spine. 2006;31(19):E Childs JD, Piva SR, and Fritz JM. Responsiveness of the numeric pain rating scale in patients with low back pain. Spine. 2005;30(11): Cholewicki J, and McGill SM. Mechanical stability of the in vivo lumbar spine: implications for injury and chronic low back pain. Clin Biomech. 1996;11(1):1 15. Chon SC, Chang KY, and You SH. Effect of the abdominal draw-in manoeuver in combination with ankle dorsiflexion in strengthening transverse abdominal muscle in healthy young adults: A preliminary, randomized, controlled study. Physiotherapy. 2010;96(2):

82 Cohen J. Statistical Power Analysis for Behavioral Science. New York: Academic Press, Cram JR, and Kasman GS. Introduction to Surface Electromyography. Gaithersburg, MD: Aspen Publishers, Cresswell AG, Grundström H, and Thorstensson A. Observations on intra-abdominal pressure and patterns of abdominal intra-muscular activity in man. Acta Physiol Scand. 1992;144(4): Critchley DJ, and Coutts FJ. Abdominal muscle function in chronic low back pain patients: measurement with real-time ultrasound scanning. Physiotherapy. 2002;88(6): Cowan SM, Bennell KL, Hodges PW, Crossley KM, and McConnell J. Simultaneous feedforward recruitment of the vasti in untrained postural tasks can be restored by physical therapy. J Orthopaed Res. 2003;21(3): d'hemecourt PA, Gerbino PG 2nd, and Micheli LJ. Back injuries in the young athlete. Clin Sports Med. 2000;19(4):

83 Dreisinger TE, and Nelson B. Management of back pain in athletes. Sports Med. 1996;21(4): Eccles JC, Sherrington CS. Reflex summation in the ipsilateral spinal flexion reflex. J Physiol. 1930;69(1):1 28. Ferreira ML, Ferreira PH, Latimer J, Herbert RD, Hodges PW, Jennings MD, Maher CG, and Refshauge KM. Comparison of general exercise, motor control exercise and spinal manipulative therapy for chronic low back pain: A randomized trial. Pain. 2007;131(1-2): Ferreira PH, Ferreira ML, and Hodges PW. Changes in recruitment of the abdominal muscles in people with low back pain: Ultrasound measurement of muscle activity. Spine. 2004;29(22): Grönblad M, Hupli M, Wennerstrand P, Järvinen E, Lukinmaa A, Kouri JP, and Karaharju EO. Intercorrelation and test-retest reliability of the Pain Disability Index (PDI) and the Oswestry Disability Questionnaire (ODQ) and their correlation with pain intensity in low back pain patients. Clin J Pain. 1993;9(3):

84 Hall L, Tsao H, MacDonald D, Coppieters M, and Hodges PW. Immediate effects of co-contraction training on motor control of the trunk muscles in people with recurrent low back pain. J Electromyogr Kinesiol. 2009;19(5): Hebert JJ, Koppenhaver SL, Parent EC, and Fritz JM. A systematic review of the reliability of rehabilitative ultrasound imaging for the quantitative assessment of the abdominal and lumbar trunk muscles. Spine. 2009;34(23):E Hibbs AE, Thompson KG, French D, Wrigley A, and Spears I. Optimizing performance by improving core stability and core strength. Sports Med. 2008;38(12): Hides J, Wilson S, Stanton W, McMahon S, Keto H, McMahon K, Bryant M, and Richardson C. An MRI investigation into the function of the transversus abdominis muscle during drawing-in of the abdominal wall. Spine. 2006;31(6):E Hides JA, Miokovic T, Belav y DL, Stanton WR, and Richardson CA. Ultrasound imaging assessment of abdominal muscle function during drawing-in of the abdominal wall: An intrarater reliability study. J Orthop Sports Phys Ther. 2007;37(8):

85 Hodges P, Cresswell A, and Thorstensson A. Preparatory trunk motion accompanies rapid upper limb movement. Exp Brain Res. 1999;124(1): Hodges P, Richardson C, and Jull G. Evaluation of the relationship between laboratory and clinical tests of transversus abdominis function. Physiother Res Int. 1996;1(1): Hodges PW. Changes in motor planning of feedforward postural responses of the trunk muscles in low back pain. Exp Brain Res. 2001;141(2): Hodges PW, Pengel LH, Herbert RD, and Gandevia SC. Measurement of muscle contraction with ultrasound imaging. Muscle Nerve. 2003;27(6): Hodges PW, and Richardson CA. Contraction of the abdominal muscles associated with movement of the lower limb. Phys Ther. 1997;77(2): Hodges PW, and Richardson CA. Inefficient muscular stabilization of the lumbar spine associated with low back pain. A motor control evaluation of transversus abdominis. Spine. 1996;21(22):

86 Hopf HC, Schlegel HJ, and Lowitzsch K. Irradiation of voluntary activity to the contralateral side in movements of normal subjects and patients with central motor disturbances. Eur Neurol. 1974;12(3): Hopkins WG. Measures of reliability in sports medicine and science. Sports Med. 2000;30(1):1 15. Jensen JL, Marstrand PC, and Nielsen JB. Motor skill training and strength training are associated with different plastic changes in the central nervous system. J Appl Physiol. 2005;99(4): Jensen MP, Chen C, and Brugger AM. Postsurgical pain outcome assessment. Pain. 2002;99(1-2): Kavcic N, Grenier S, and McGill SM. Quantifying tissue loads and spine stability while performing commonly prescribed low back stabilization exercises. Spine. 2004;29(20): Kiesel KB, Uhl T, Underwood FB, and Nitz AJ. Rehabilitative ultrasound measurement of select trunk muscle activation during induced pain. Man Ther. 2008;13(2):

87 Kumar S, Sharma VP, and Negi MP. Efficacy of dynamic muscular stabilization techniques (DMST) over conventional techniques in rehabilitation of chronic low back pain. J Strength Cond Res. 2009;23(9): Legg SJ. The effect of abdominal muscle fatigue and training on the intra-abdominal pressure developed during lifting. Ergonomics. 1981;24(3): Love A, Leboeuf C, and Crisp TC. Chiropractic chronic low back pain sufferers and self-report assessment methods. Part I. A reliability study of the Visual Analogue Scale, the Pain Drawing and the McGill Pain Questionnaire. J Manipulative Physio Ther. 1989;12(1): MacDonald DA, Moseley GL, and Hodges PW. The lumbar multifidus: does the evidence support clinical beliefs? Man Ther. 2006;11(4): MacDougall JD, Gibala MJ, Tarnopolsky MA, MacDonald JR, Interisano SA, and Yarasheski KE. The time course for elevated muscle protein synthesis following heavy resistance exercise. Can J Appl Physiol. 1995;20(4): Macedo LG, Maher CG, Latimer J, and McAuley JH. Motor control exercise for persistent, nonspecific low back pain: A systematic review. Phys Ther. 2009;89(1):

88 Manniche C, Asmussen K, Lauritsen B, Vinterberg H, Kreiner S, and Jordan A. Low back pain rating scale: validation of a tool for assessment of low back pain. Pain. 1994;57(3): Mannion AF, Pulkovski N, Gubler D, Gorelick M, O Riordan D, Loupas T, Schenk P, Gerber H, and Sprott H. Muscle thickness changes during abdominal hollowing: an assessment of between-day measurement error in controls and patients with chronic low back pain. Eur Spine J. 2008;17(4): Mannion AF, Pulkovski N, Toma V, and Sprott H. Abdominal muscle size and symmetry at rest and during abdominal hollowing exercises in healthy control subjects. J Anat. 2008;213(2): Marshall P, and Murphy B. The validity and reliability of surface EMG to assess the neuromuscular response of the abdominal muscles to rapid limb movement. J Electromyogr Kinesiol. 2003;13(5): Martin BI, Deyo R, Mirza SK, Turner JA, Comstock BA, Hollingworth W, and Sullivan SD. Expenditures and health status among adults with back and neck problems. JAMA. 2008;299(6):

89 McGill SM. The biomechanics of low back injury: implications on current practice in industry and the clinic. J Biomech. 1997; 30(5): McMeeken JM, Beith ID, Newham DJ, Milligan P, and Critchley DJ. The relationship between EMG and change in thickness of transversus abdominis. Clin Biomech. 2004;19(4): Moore JC. Excitation overflow: An electromyographic investigation. Arch Phys Med Rehabil. 1975;56(3): Moseley GL, Hodges PW, and Gandevia SC. Deep and superficial fibers of the lumbar multifidus muscle are differentially active during voluntary arm movements. Spine. 2002;27(2):E Nordin M, and Frankel VH. Basic Biomechanics of the Musculoskeletal System. 3rd ed. Philadelphia: Lippincott & Williams, O Sullivan PB, Phyty GD, Twomey LT, and Allison GT. Evaluation of specific stabilizing exercise in the treatment of chronic low back pain with radiologic diagnosis of spondylolysis or spondylolisthesis. Spine. 1997;22(24):

90 Pengel LH, Herbert RD, Maher CG, and Refshauge KM. Acute low back pain: Systematic review of its prognosis. BMJ. 2003;327(7410):323. Rankin G, and Stokes M. Reliability of assessment tools in rehabilitation: An illustration of appropriate statistical analyses. Clin Rehabil. 1998;12(3): Richardson CA, Hodges PW, and Hides JA. Therapeutic Exercise for Lumbopelvic Stabilization: A motor control approach for the treatment and prevention of low back pain. 2nd ed. Edinburgh: Churchill Livingstone, Richardson CA, Jull GA, Toppenberg R, and Commerford M. Techniques for active lumbar spine stabilisation for spinal protection: a pilot study. Aust J Physiother. 1992;38: Roussel N, Nijs J, Truijen S, Vervecken L, Mottram S, and Stassijns G. Altered breathing patterns during lumbopelvic motor control tests in chronic low back pain: A case-control study. Eur Spine J. 2009;18(7): Shimura K, and Kasai T. Effects of proprioceptive neuromuscular facilitation on the initiation of voluntary movement and motor evoked potentials in upper limb muscles. Hum Mov Sci. 2002;21(1):

91 Shrout PE, and Fleiss JL. Intraclass correlations: Uses in assessing rater reliability. Psychol Bull. 1979;86(2): Standaert CJ, and Herring SA. Expert opinion and controversies in musculoskeletal and sports medicine: core stabilization as a treatment for low back pain. Arch Phys Med Rehabil. 2007;88(12): Stanton T, and Kawchuk G. The effect of abdominal stabilization contractions on posteroanterior spinal stiffness. Spine. 2008;33(6): Stuge B, Veierod MB, Laerum E, Bragelian M, and Vollestad N. The efficacy of a treatment program focusing on specific stabilizing exercises for pelvic girdle pain after pregnancy: a two-year follow-up of a randomized clinical trial. Spine. 2004;29(10):E Tait RC, and Chibnall JT. Factor structure of the pain disability index in workers compensation claimants with low back injuries. Arch Phys Med Rehabil. 2005;86(6): Teyhen DS, Miltenberger CE, Deiters HM, Del Toro YM, Pulliam JN, Childs JD, Boyles RE, and Flynn TW. The use of ultrasound imaging of the abdominal

92 drawing-in maneuver in subjects with low back pain. J Orthop Sports Phys Ther. 2005;35(6): Torres-Oviedo G, Macpherson JM, and Ting LH. Muscle synergy organization is robust across a variety of postural perturbations. J Neurophysiol. 2006;96(3): Urquhart DM, Hodges PW, Allen TJ, and Story IH. Abdominal muscle recruitment during a range of voluntary exercises. Man Ther. 2005;10(2): Vera-Garcia FJ, Elvira JL, Brown SH, and McGill SM. Effects of abdominal stabilization maneuvers on the control of spine motion and stability against sudden trunk perturbations. J Electromyogr Kinesiol. 2007;17(5): von Garnier K, Köveker K, Rackwitz B, Kober U,Wilke S, Ewert T, and Stucki G. Reliability of a test measuring transversus abdominis muscle recruitment with a pressure biofeedback unit. Physiotherapy. 2009;95(1):8 14. Walker BF, and Williamson OD. Mechanical or inflammatory low back pain. What are the potential signs and symptoms? Man Ther. 2009;14(3):

93 Whittaker JL. Ultrasound imaging of the lateral abdominal wall muscles in individuals with lumbopelvic pain and signs of concurrent hypocapnia. Man Ther. 2008;13(5):

94 Appendices

95 Appendix A. Pain Disability Index The rating scales below are designed to measure the degree to which several aspects of your life are presently disrupted by chronic pain. In other words, we would like to know how much your pain is preventing you from doing what you would normally do, or from doing it as well as you normally would. Respond to each category by indicating the overall impact of pain in your life, not just when the pain is at its worst. For each of the 7 categories of life activity Listed, please circle the number on the scale which describes the level of disability you typically experience. A score of 0 means no disability at all, and a score of 10 signifies that all of the activities in which you would normally be involved have been totally disrupted or prevented by your pain. (1) Family/home responsibilities This category refers to activities related to the home or family. It includes chores or duties performed around the house (e.g., yard work) and errands or favors for other family members (e.g., driving the children to school) No disability Total disability (2) Recreation

96 This category includes hobbies, sports, and other similar leisure time activities No disability Total disability (3) Social activity This category refers to activities which involve participation with friends and acquaintances other than family members. It includes parties, theater, concerts, dining out, and other social functions No disability Total disability (4) Occupation This category refers to activities that are a part of or directly related to one s job. This includes non-paying jobs as well, such as that of a housewife or volunteer worker No disability Total disability (5) Sexual behavior This category refers to the frequency and quality of one s sex life No disability Total disability

97 (6) Self-care This category includes activities which involve personal maintenance and independent daily living (e.g., taking a shower, driving, getting dressed, etc.) No disability Total disability (7) Life-support activity This category refers to basic life-supporting behaviors such as eating, sleeping, and breathing No disability Total disability

98 Appendix B. Pain Rating Scale Manniche et al developed rating scale to evaluate patients with low back pain. The scale covers the 4 manifest components of back pain and was designed for monitoring outcome following therapeutic interventions. The authors are from several hospitals in Denmark. Measures in rating scale: (1) Back and leg pain (60 points) (2) Disability index (30 points) (3) Physical impairment (40 points) Back and Leg Pain Visual analogue scales (VAS) ranging from 0 (no pain) to 10 (worst imaginable pain): (1) Back pain at the time of the examination (2) Leg pain at the time of the examination (3) The worst back pain within the last 2 weeks (4) The worst leg pain within the last 2 weeks (5) Average level of back pain during the last 2 weeks (6) Average level of leg pain during the past 2 weeks Pain index=sum (points for all 6 visual analogue scales)

99 Disability Index Questions (1) Can you sleep at night without low back pain interfering? (2) Can you do your daily work without low back pain reducing your activities? (3) Can you do the easy chores at home such as watering flowers or cleaning the table? (4) Can you put on shoes and stockings by yourself? (5) Can you carry two full shopping bags (10 kilograms total)? (6) Can you get up from a low armchair without difficulty? (7) Can you bend over the wash basin to brush your teeth? (8) Can you climb stairs from one floor to another without resting because of low back pain? (9) Can you walk 400 meters without resting because of low back pain? (10) Can you run 100 meters without resting because of low back pain? (11) Can you ride a bike or drive a car without feeling any low back pain? (12) Does low back pain influence your emotional relationship to your nearest family? (13) Did you have to give up contact with other people within the last 2 weeks because of low back pain? (14) If it was a present interest do you think that there are certain jobs which you would not be able to manage because of your back trouble? (15) Do you think that the low back pain will influence your future?

100 Responses Points Forward Reverse Not a problem 0 Yes No Can be a problem 1 Can Can be Is a problem 2 No Yes Forward questions: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 Reverse questions: 12, 13, 14, 15 NOTE: In the paper scoring is given as yes = 0; can be problem = 1; no = 2. However these responses for the last 4 questions reverse the general trend of the first 11 questions. It makes more sense to me to reverse the scoring for the last 4 questions. Disability index=sum (points for all 15 questions) Physical Impairment (1) Endurance of back muscles: length of time that the patient can lie horizontal above the floor with the legs strapped to a bench and the trunk unsupported from the level of the iliac crest (2) Back mobility: modified Schober's test (a) draw a line between the posterior iliac spines then (b) identify a point 10 cm above the midpoint of the line then (c) with the person bending forward measure the distance from that point to the midpoint of the line connecting the posterior iliac spines and (d) determine the distraction = increase in measurement while bending forward. (3) Overall mobility: fastest time taken to go from (a) lying supine on a flat couch 80 cm above the floor to (b) standing beside the couch then (c) walking to the end of the couch where (d) a deep knee bend is done and then (e) return to the starting position

101 (4) Use of analgesics: based on the frequency of use for non-narcotic and narcotic analgesics Measures Finding Points 270 seconds seconds seconds seconds seconds 4 back muscle endurance seconds seconds seconds seconds seconds 9 0 seconds mm 0 back mobility mm mm 4 (modified Schober's test) mm mm mm 10 < 10 seconds seconds 2 overall mobility test seconds seconds seconds 8 50 seconds 10 none during past week 0 use NSAID or non-narcotic analgesic 1 4 times a week 2 analgesic use use of NSAID or non-narcotic analgesic 5+ times a week 4 use of morphine or analogues 1 4 times a week 8 use of morphine or analogues 5+ times a week 10 Impairment index=sum (points for all 4 measures)

102 Interpretation: minimum score for sub-scores and total: 0 maximum pain index: 60 maximum disability index: 30 maximum physical impairment: 40 maximum total points: 130 The higher the score the greater the level of disability and impairment. Performance: The scale was found to be reliable based on comparisons with the Global Assessments reported by an experienced clinician and the patient. Inter-rater agreement is high

103 Appendix C. Multivariate tests of ANOVA in SPSS Multivariate tests of ANOVA in SPSS program for comparison of the abdominal muscle contraction thickness between groups