Article

Trunk Muscle Recruitment Patterns in Patients With Low Back Pain Enhance the Stability of the Lumbar Spine

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Abstract

A comparative study of trunk muscle recruitment patterns in healthy control subjects and patients with chronic low back pain was conducted. To assess trunk muscle recruitment in patients with low back pain. Conflicting evidence has been reported on the level and pattern of trunk muscle recruitment in patients with low back pain. The disparities can be explained partly by methodologic differences. It was hypothesized that trunk muscle recruitment patterns may be altered in patients with low back pain to compensate for reduced spinal stability. For this study, 16 patients with low back pain and 16 matched control subjects performed slow trunk motions about the neutral posture and isometric ramp contractions while seated upright. Ratios of electromyographic amplitudes and estimated moment contributions of antagonist over agonist muscles and of segmentally inserting muscles over muscles inserting on the thorax and pelvis only were calculated. In addition, model simulations were performed to assess the effect of changes in muscle recruitment on spinal stability. The ratios of antagonist over agonist, and of lumbar over thoracic erector spinae electromyographic amplitude and estimated moment contributions were greater in the patients than in the control subjects. The simulation model predicted that these changes would effectively increase spinal stability. Trunk muscle recruitment patterns in patients with low back pain are different from those in healthy control subjects. The differences are likely to be functional with respect to enhancement of spinal stability in the patients.

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... NSCLBP causes dysfunction of trunk muscles, and dysfunction of trunk muscles can also cause chronicity [7][8][9][10]. Trunk muscles are divided into local (e.g., transversus abdominis and multifidus) and global (e.g., erector spinae, rectus abdominis, internal and external obliques, quadratus lumborum, gluteus maximus, and latissimus dorsi) muscles based on functional differences [11]. ...
... It has been reported that individuals with LBP show inactivity in the local muscles [7,[12][13][14] and increased activity in the global muscle groups [12][13][14][34][35][36][37]. The amplitude of transversus abdominis activity was significantly decreased, and the onset timing of transversus abdominis muscle and internal oblique/transversus abdominis muscle was significantly delayed during rapid upper and lower limb movement in individuals with NSCLBP compared to the healthy individuals [8][9][10][11]. The transversus abdominis muscle attaches to the thoracolumbar fascia and is thought to contribute to spinal intersegmental rigidity by exerting lateral tension on the thoracolumbar fascia [34]. In addition, the activity of the transversus abdominis muscle is thought to increase intra-abdominal pressure, thus contributing to the rigidity of the interspinal segments [35,36]. ...
... These local muscle dysfunctions may lead to spinal intersegmental instability. Besides, in the global muscle, it has been reported that the lumbar and thoracic erector spinae exhibit a higher amplitude of activity during active trunk movements in individuals with NSCLBP than the healthy controls [8]. Increased global muscular activity increases spine stress [38], impairing spine mobility and contributing to shock absorption/damping [39]. ...
Article
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Core exercises on an unstable surface increase trunk muscle activity, especially for local muscle groups. Therefore, there is a possibility that exercises on an unstable surface would be effective in the rehabilitation of non-specific chronic low back pain (NSCLBP). The present study assessed trunk muscle activities during bridge exercise on the floor and two kinds of unstable surfaces, i.e., a balance ball and the BOSU, for individuals with and without NSCLBP. This study enrolled 17 and 18 young participants with and without NSCLBP, respectively. In the balance ball condition, both groups showed a significant increase in erector spinae activity compared to the floor condition, and the increase in activity was significantly greater in the NSCLBP group than in the control group (p = 0.038). On the other hand, neither group showed significant changes in trunk muscle activities in the BOSU condition compared to those in the floor condition. The control group showed a significant increase in internal oblique/transversus abdominis activity under the balance ball condition (p = 0.020), whereas there were no significant changes in these muscle activities between the balance ball and floor conditions in the NSCLBP group. The present study showed that participants with NSCLBP significantly increased muscle activity of the erector spinae, one of the global back muscles, on the balance ball in spite of small effects on muscle activity of the internal oblique/transversus abdominis, which is one of the local abdominal muscles. Therefore, attention should be paid to the application of bridge exercises on the balance ball for individuals with NSCLBP.
... The superficial-layer musculature includes the rectus abdominis, external oblique (EO) and erector spinae muscles and contributes to an efficient force and energy transfer between the upper and lower limbs [13,14]. The increasing of the muscular stiffness by synergistic cocontraction of all involved core muscles is essential to assure the stabilisation of the lumbar spine and preserve trunk posture [15][16][17]. ...
... Both muscles almost achieved levels of very high muscle activity, reaching values of 60% MVIC for the RA and around 56% for both sides of the IO. Based on previous research, this may be due to a greater muscular effort to provide the necessary active stiffness by synergistic cocontraction of the deep and superficial core muscles to supply more efficiently the stabilising and weight-bearing demands for this flexion variation [10][11][12]16,17,36]. For the EO muscles, the sEMG response was moderate, differing slightly between both EO sides, and did not change for the LES which continued showing low levels of muscle activity in flexion as well. ...
... It can be assumed that the enhancement of the sEMG response is due, among other factors, to an increase in neural muscle recruitment [71]. When the contraction is isometric, as occurring in this bridging exercise, this increase in abdominal recruitment reflects a greater production of force and muscular stiffness to stabilise the trunk [15,16]. This suggests that the active head flexion may have had a greater stiffening effect on the abdominal muscles, which would ultimately enhance trunk stabilisation during the exercise performance. ...
Article
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This study aimed to investigate the influence of head position on the electromyographical activity of the core muscles during the prone plank exercise. Twenty healthy participants were enrolled in this study. Muscle activation was registered using surface electromyography in the rectus abdominis, external oblique, internal oblique, and the lumbar portion of erector spinae. Three plank conditions were randomly evaluated, varying the position of the cranio-cervical segment during the plank performance (neutral, flexion and extension). The activation of each individual examined muscle and the overall core muscle activity (Total Intensity), as well as the ratings of perceived exertion were analysed with statistical significance set at p < 0.05. Flexion revealed significantly higher Total Intensity values compared to neutral and extension (p < 0.001; effect size (ES) > 0.90). The rectus abdominis presented larger activation in flexion compared to the other variations (p < 0.05; ES > 0.70). Flexion elicited a greater response for both sides of external oblique when compared to neutral and extension, and also for both sides of internal oblique compared to the other conditions (p < 0.05; ES > 0.70). Both flexion and extension reported higher exertion rating values compared to neutral (p < 0.05; ES > 0.90). Head position influenced the electromyographical activation of core musculature, showing highest values when performing the plank in a head flexion.
... The superficial-layer musculature includes the rectus abdominis (RA), external oblique (EO) and erector spinae muscles and contributes to an efficient force and energy transfer between the upper and lower limbs [13,14]. The increasing of the muscular stiffness by synergistic cocontraction of all involved core muscles is essential to assure the stabilisation of the lumbar spine and preserve trunk posture [15][16][17]. ...
... Both muscles almost achieved levels of very high muscle activity, reaching values of 60% MVIC for the RA and around 56% for both sides of the IO. Based on previous research, this may be due to a greater muscular effort to provide the necessary active stiffness by synergistic cocontraction of the deep and superficial core muscles to supply more efficiently the stabilising and weight-bearing demands for this FLEXION variation [10][11][12]16,17,31]. For the EO muscles, the sEMG response was moderate, differing slightly between both EO sides, and did not change for the LES which continued showing low levels of muscle activity in FLEXION as well. ...
... It can be assumed that the enhancement of the sEMG response is due, among other factors, to an increase in neural muscle recruitment [66]. When the contraction is isometric, as occurring in the prone plank exercise, this increase in abdominal recruitment reflects a greater production of force and muscular stiffness to stabilise the trunk [15,16]. This suggests that the active cranio-cervical flexion may have had a greater stiffening effect on the abdominal muscles, which would ultimately enhance trunk stabilisation during the exercise performance. ...
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This study aimed to investigate the influence of cranio-cervical position on the electromyographical activity of the core muscles during the prone plank exercise. Twenty healthy participants were enrolled in this study. Muscle activation was registered using surface electromyography (sEMG) in the rectus abdominis (RA), external oblique (EO), internal oblique (IO) and lumbar portion of erector spinae (LES). Three prone plank conditions were randomly evaluated, varying the position of the cranio-cervical segment during the prone plank performance (NEUTRAL, FLEXION and EXTENSION). sEMG signals of each individual muscle, Total Intensity (TI) and ratings of perceived exertion (RPE) were analysed with statistical significance set at P<0.05. FLEXION revealed significantly higher TI values compared to NEUTRAL and EXTENSION (p = 0.000; effect size (ES) > 0.90). The RA presented larger activation in FLEXION compared to the other variations (p < 0.05; ES >0.70). FLEXION elicited a greater response compared to NEUTRAL for both sides of EO when compared to EXTENSION, and also for both sides of IO compared to the other conditions. Both FLEXION and EXTENSION reported higher RPE values compared to NEUTRAL. Cranio-cervical segment position influenced the electromyographical activation of core musculature, showing highest values when performing prone plank in a cranio-cervical flexion.
... MVCs are also difficult even for healthy workers as they need to be well motivated (Jung & Hallbeck, 2004) and ideally trained (Larivière et al., 2014;Sale et al., 1983) to perform "real" MVCs. To circumvent such MVC concerns, submaximal voluntary contractions (SVCs) have been proposed (Cholewicki et al., 2011;Dufour et al., 2013;Van Dieën et al., 2003), which can be integrated within an EMG-assisted optimization framework (Ghezelbash et al., 2022). ...
... The ratio variables are hypothesized to be useful model outcomes to study trunk muscle coordination strategies in patients with LBP (Van Dieën et al., 2003. Abdominal to back muscle ratio was different between all models (Fig. 4) but further pairwise comparisons between GAIN and MVC models showed that the effect sizes were small in all four experimental conditions (η 2 G ≤ 0.102). ...
... Van Dieën et al., 2003; and (3) Highly aggregated outcomes: (i) L4/L5 Intradiscal Pressure (IDP) ...
Article
Background Multijoint EMG-assisted optimization models are reliable tools to predict muscle forces as they account for inter- and intra-individual variations in activation. However, the conventional method of normalizing EMG signals using maximum voluntary contractions (MVCs) is problematic and introduces major limitations. The sub-maximal voluntary contraction (SVC) approaches have been proposed as a remedy, but their performance against the MVC approach needs further validation particularly during dynamic tasks. Methods To compare model outcomes between MVC and SVC approaches, nineteen healthy subjects performed a dynamic lifting task with two loading conditions. Results Results demonstrated that these two approaches produced highly correlated results with relatively small absolute and relative differences (<10%) when considering highly-aggregated model outcomes (e.g. compression forces, stability indices). Larger differences were, however, observed in estimated muscle forces. Although some model outcomes, e.g. force of abdominal muscles, were statistically different, their effect sizes remained mostly small (ηG2 ≤ .13) and in a few cases moderate (ηG2 ≤ .165). Conclusion The findings highlight that the MVC calibration approach can reliably be replaced by the SVC approach when the true MVC exertion is not accessible due to pain, kinesiophobia and/or the lack of proper training.
... 24 Also, a study analyzed the relative L/G ratio of the lumbar to thoracic ES muscular activity during isometric contractions in activities like flexion, extension, and lateral flexion from a semiseated position in an apparatus and estimated moment contributions were greater in the patients than in the control subjects. 38 In addition to the L/G ratio, previous researchers advocated for a gluteal-to-TFL muscle activation (GTA) index, where higher values indicate greater activation of GMax and GMed relative to TFL. 32 This index determines which exercises target gluteal activation while minimizing TFL activation to prevent abnormal hip kinematics (excessive abduction and internal rotation). 32 They recommended the clam, side step, the unilateral bridge, and quadruped hip extension exercises could be used to preferentially activate the gluteal muscles over TFL. ...
... The lumbar stabilization exercises mainly target the local muscles 35 ; however, there is some evidence that the high-load lumbar stabilization exercises, such as bridge exercises, could recruit both local and global muscles. 9,22 MF as the local muscle controls and ensures the spine curvature in sagittal and lateral stiffness to maintain mechanical stability of the lumbar spine 38 while ES as the global muscle produces torque to maintain overall trunk alignment. 38 The muscles of the hip transfer the loads of the tasks via the sacroiliac joint to the trunk and vice versa. ...
... 9,22 MF as the local muscle controls and ensures the spine curvature in sagittal and lateral stiffness to maintain mechanical stability of the lumbar spine 38 while ES as the global muscle produces torque to maintain overall trunk alignment. 38 The muscles of the hip transfer the loads of the tasks via the sacroiliac joint to the trunk and vice versa. 42 If the difficulty of the tasks and the magnitude of their loads are excessively beyond the tolerance of the hip muscles and joints, they can result in pressure on the lumbar joints, sacroiliac joint, pubic symphysis, and consequently functional failure of the sacroiliac joint and low back pain. ...
Article
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Background: There is some evidence that high-load lumbar stabilization exercises, such as back bridge, can recruit both local and global muscles. Hypothesis: Therapeutic exercises would optimize gluteus maximus (GMax), gluteus medius (GMed), multifidus (MF), and transversus abdominis (TrA) activation, while minimizing the activation of the tensor fascia latae (TFL) and erector spinae (ES) muscles in healthy individuals. Design: Cross-sectional study. Setting: Research laboratory. Level of Evidence: Level 4. Methods: In this cross-sectional study, surface electromyography (EMG) of GMax, GMed, TFL, TrA, MF, and ES was used to quantify the gluteal-to-TFL muscle activation (GTA) index and a ratio of local to global (L/G) lumbar muscles during (1) the elbow-toe exercise in the prone position, (2) the elbow-toe with right left lifted, (3) the hand-knee with left arm and right leg lifted, (4) the back bridge, (5) the back bridge with right leg lifted, (6) the back bridge with left leg lifted, (7) the side bridge with left leg lifted, (8) the side bridge with right leg lifted, and (9) the elbow-toe with right leg horizontally lifted exercises in healthy individuals (20 men, 20 women; age, 25 ± 4 years). Results: The back bridge exercise with left leg lift generated the highest L/G muscles activity ratio (L/G = 3.35) while the hand-knee exercise yielded the lowest L/G muscles activity ratio (L/G = 1.21). The side bridge exercise with left elbow and foot and lifting the right leg (GTA = 63.78), hand-knee exercise (GTA = 49.62), back bridge (GTA = 28.05), and elbow-toe exercise with left leg horizontally lifted (GTA = 23.02) generated the highest GTA indices, respectively. Meanwhile, the normalized EMG amplitude for GMax was significantly less than the TFL, for elbow-toe exercise (P < 0.001), back bridge with left leg lift (P = 0.001), side bridge exercise with the right elbow and foot and lifting the left leg (P = 0.002), and elbow-toe exercise with right leg horizontally lifted (P < 0.001). Conclusion: The highest GTA indexes were observed during (1) the side bridge lifting the dominant leg and (2) the hand-knee horizontally lifting dominant leg, respectively. The L/G ratio was highest during (1) the back bridge lifting nondominant leg, (2) back bridge, and (3) back bridge lifting dominant leg, respectively. This study supports the use of back bridge exercises to strengthen the MF and side bridges to improve gluteal muscle activation. Clinical Relevance: The highest GTA index was observed in the side bridge lifting the right leg. Highest L/G ratio was in the back bridge with nondominant leg lifted. This study supports the use of back bridge exercises to strengthen the MF. This study supports the use of side bridges to improve gluteal muscle activation. Keywords gluteal-to-tensor fascia latae activation (GTA) index, local/global (L/G) ratio, core stabilization exercise, healthy individual
... 3,4 Impaired motor control has been implicated in the disability associated with NSCLBP. 3,5 There is considerable evidence that trunk muscle activity levels differ between people with LBP and painfree people, 6,7 though the nature and direction of these changes are debated. Some studies report decreased muscle activity levels in people with LBP. 8 In contrast, other studies have demonstrated increased muscle activation in people with CLBP. ...
... Interpreting how trunk muscle activity is altered in people with NSCLBP and what this means for clinical management is critical. In a comprehensive overview of motor control changes in people with NSCLBP, van Dieën et al 5,7 highlighted the likelihood that different "phenotypes" of LBP may present. For example, van Dieën et al 7 proposed there might be NSCLBP subgroups with "tight control" over trunk movement at one end of a spectrum and "loose control" at the other end of that spectrum. ...
Article
The study compared superficial trunk muscle activity and postural control among an active extension subgroup of people with nonspecific chronic low back pain (AE-NSCLBP) with painfree controls during functional tasks. Thirty-two people (17 people with low back pain [LBP] and 15 painfree controls) participated in this study. Muscle activity of 5 trunk muscles and postural control were investigated during both standing tasks (eyes open/closed; single/double-leg balance) and dynamic functional tasks (spinal forward flexion and return, and a sit to stand transfer). Results showed that during single-leg standing, people with AE-NSCLBP exhibit higher muscle activity than painfree controls for 3 trunk muscles, especially with their eyes closed. There were no significant differences in muscle activity between eye conditions during double-leg standing and sit to stand transfer, forward flexion, and return from flexion. The AE-NSCLBP subgroup also demonstrated significantly impaired postural control (lower time to boundary) in 4 of 8 conditions, especially during single-leg standing and with their eyes closed. These findings show people with LBP typically demonstrated greater trunk muscle activity and poorer postural control while maintaining standing posture. This pattern was most evident when the postural challenge was higher, such as single-leg standing or with eyes closed. While this study design cannot infer causality, these findings have implications for LBP rehabilitation, particularly regarding approaches which seek to alter muscle activation among people with LBP.
... Global muscles contribute to the regulation of spinal orientation, the balancing of extrinsic burdens, and the production of a substantial amount of torque for spinal movement. People with LBP are preferentially biased toward posture-specific activation of global muscles, which are larger and more superficial, than local muscles, which fine-tune intersegmental movement (van Dieën et al., 2003a;Ferguson et al., 2004;Marras et al., 2004;Claus et al., 2018). Although excessive activity of these muscles contributes to spinal stability, it also increases the load on the spine and is considered a risk factor for LBP (van Dieën et al., 2003b;Hodges et al., 2013). ...
... Previous studies have reported that individuals with LBP overactivate their global muscle groups. Increased global muscle activity increases spine stress (van Dieën et al., 2003a;Ferguson et al., 2004;Marras et al., 2004), and this may contribute to LBP (van Dieën et al., 2003b;Hodges et al., 2013). In addition, repeated excessive muscle activity is believed to cause muscle pain (Johansson and Sojka, 1991;Visser and van Dieën, 2006). ...
Article
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This study aimed to determine the differences in trunk muscle activity during rowing at maximal effort between rowers with and without low back pain (LBP). Ten rowers with LBP and 12 rowers without LBP were enrolled in this study. All rowers performed a 500-m trial using a rowing ergometer at maximal effort. The amplitudes of the activities of the thoracic erector spinae (TES), lumbar erector spinae (LES), latissimus dorsi (LD), rectus abdominis (RA), and external oblique (EO) muscles were analyzed using a wireless surface electromyography (EMG) system. EMG data at each stroke were converted into 10-time series data by recording averages at every 10% in the 100% stroke cycle and normalized by maximum voluntary isometric contraction in each muscle. Two-way repeated measures analysis of variance was performed. Significant interactions were found in the activities of the TES and LES (P < 0.001 and P = 0.047, respectively). In the post hoc test, the TES activity in the LBP group was significantly higher than that in the control group at the 10% to 20% and 20% to 30% stroke cycles (P = 0.013 and P = 0.007, respectively). The LES activity in the LBP group was significantly higher than that in the control group at the 0% to 10% stroke cycle (P < 0.001). There was a main group effect on the LD activity, with significantly higher activity in the LBP group than in the control group (P = 0.023). There were no significant interactions or main effects in the EO and RA activities between the groups. The present study showed that rowers with LBP compared with those without LBP exhibited significantly higher TES, LES, and LD muscle activities. This indicates that rowers with LBP exhibit excessive back muscle activity during rowing under maximal effort.
... Low back pain (LBP) is associated with postural control changes, some of which are considered to protect the painful area from further pain, injury or re-injury [1,2]. These postural characteristics have been typically observed during the later stages of LBP [2][3][4], and are thought to be detrimental if maintained beyond the initial acute/repair phase as they can increase spinal loads and reduce movement [5,6]. ...
... Compromised balance performance has also been argued to result from stiffening of the trunk [1,2], either to protect the back from real or perceived threat of further pain/injury [5], or to reduced reliance on proprioception which is necessary to fine tune coordinated muscle activation [29]. Elevated co-activation of trunk muscles would provide quicker responses to disturbances but might negatively impact balance control [15]. ...
Article
Background: Low back pain (LBP) is associated with altered postural control, mostly observed at later stages in the LBP trajectory. It is unclear whether postural control differs in the acute phase of LBP. Research question: Is postural control different in the acute phase of LBP (<2 weeks) and do differences depend on pain intensity, psychological features and/or availability of vision to control posture? Methods: Cross-sectional study design. An unstable sitting paradigm (to reduce the contribution of the legs) assessed postural control of participants with acute LBP (n=133) and pain-free controls (n=74). Centre of pressure (CoP) reflected seat movements. Participants balanced with eyes closed, open, or with visual feedback of the anteroposterior CoP position. Balance performance was expressed by CoP displacement and velocity, and stabilogram diffusion analysis. Generalized estimating equations (GEEs) including body mass index, sex, and safety bar touch, tested differences between groups and between balance conditions. Separate GEEs were used to model performance measures and bar touch (yes/no) including pain intensity, disability and psychological features. Results: CoP displacement and critical point coordinates (time and distance where CoP diffusion rate or spread slows) were larger in LBP than pain-free controls independent of balance condition. Long-term diffusion rate was greater in LBP than controls with eyes closed. CoP velocity measures (RMS, short term diffusion rate) were not different between groups. Pain intensity and psychological features were not linearly related to balance performance in participants with acute LBP. Higher pain catastrophizing was associated with touching the safety bar. Significance: Postural control differs in acute LBP than pain-free controls. Findings might be explained by altered sensory processing, lesser ability to reweight proprioceptive information and/or less accurate trunk muscle control. Although not linearly related to pain-intensity or psychological features in the acute stage, reduced balance performance could potentially have impact on LBP recovery.
... Their adaptive strategy could be used to prevent possible fall injuries. The co-contraction of the lower limb muscles could be explained as longer delays to the mechanical disturbance, which may cause a smaller angular deviation of the trunk [22,23]. As lower limb function involves postural stability, our study utilized the preferential side to better discriminate the behavior on limb preference [24]. ...
... We also expected a trunk stiffening strategy might occur because of reduced trunk motion (possibly due to pain). These patterns are likely to be functional to enhance postural stability in the LBP group [23]. However, the somatosensory integration for the control of the preferred foot placement in subsequent trials was based on swing and step times in the initial trial in order to enhance gait stability. ...
Article
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A compensatory stepping strategy following repeated perturbations may compromise dynamic balance and postural stability. However, there is a lack of study on preferred limb reaction, swing, and step time adjustments. The purpose of this study was to investigate limb reaction, swing, and recovery step times following repeated trip perturbations in individuals with and without non-specific chronic low back pain (LBP). There were 30 subjects with LBP and 50 control subjects who participated in the study. The limb reaction, swing, and recovery step times (s) were measured following treadmill-induced random repeated perturbations (0.12 m/s velocity for 62.5 cm displacement), which caused subjects to move forward for 4.90 s. Both groups demonstrated a significant interaction of repetitions and times (F = 4.39, p = 0.03). Specifically, the recovery step time was significantly shorter in the LBP group during the first trip (t = 2.23, p = 0.03). There was a significant interaction on repetitions and times (F = 6.03, p = 0.02) in the LBP group, and the times were significantly different (F = 45.04, p = 0.001). The initial limb reaction time of the LBP group was significantly correlated with three repeated swing times to avoid falls. The novelty of the first trip tends to enhance a protective strategy implemented by the LBP group. Although limb preference did not demonstrate a significant difference between groups, the LBP group demonstrated shorter recovery step times on their preferred limb initially in order to implement an adaptive strategy to avoid fall injuries following repeated perturbations.
... Teniendo en cuenta que tanto la plancha frontal como la extensión isométrica de tronco que se considerarían ejercicios simétricos (con una supuesta demanda equitativa en ambos hemicuerpos), y el comportamiento observado en este caso, podríamos pensar, pero no concluir, que estaríamos ante un caso que refleja una conducta adaptativa, una compensación funcional a algún factor extra que no ha sido tenido en cuenta en este análisis. Observamos similitud de resultados con estudios realizados con pacientes con dolor lumbar crónico, en donde se reportan aumentos en la actividad eléctrica, particularmente del oblicuo mayor, y un patrón de reclutamiento alterado, coincidentes, a priori, con nuestro caso (Calatayud, 2019;Kim, 2013;Shamsi, 2020;Silfies, 2005, van Dieën, 2003. Asimismo, existe la posibilidad de que la causa de estos valores observados en el análisis electromiográfico pueda darse debido a una estrategia de control postural como consecuencia de una escoliosis, ya que se encontró en la literatura evidencia que sujetos con esta patología presentaban patrones anormales de activación ante demandas simétricas, comparados con Kuo, 2011). ...
... Ambos músculos presentan mucha más actividad que sus contralaterales sin importar el ejercicio o el rol que se les demandan, sin embargo, estos resultados no son concluyentes puesto que fueron obtenidos en un solo sujeto del cual se desconoce la existencia de alguna variable capaz de explicar el comportamiento observado, que probablemente podría estar relacionado a una respuesta adaptativa a algún factor no conocido. La evidencia nos sugiere que cambios en los patrones de reclutamiento son una adaptación a la inestabilidad espinal resultante de la laxitud o daño osteoligamentoso, disfunción muscular o control neuromuscular reducido (Silfies, 2005), como así también del dolor, la fatiga muscular (Enoka, 2008;Tsuboi, 1994), o una anomalía escoliótica. Sin embargo, no se puede atribuir a ninguno de estos factores los resultados obtenidos debido a que no han sido tenidos en cuenta en este estudio. ...
Article
Full-text available
Core stability has gained importance due to its role in movement and its relationship with low back pain, in this sense, various models have been proposed to explain its performance, without a clear consensus yet. The aim of this study was to quantitatively analyze the activation and participation of the trunk musculature in isometric exercises related to central stability. A 23-year-old student from the Facultad de Educación Física (UNT) was evaluated. Through surface electromyography, the activity of the external oblique, internal oblique, multifidus and gluteus maximus was bilaterally examined in four isometric exercises, prone plank, isometric trunk extension and right and left side plank. The results obtained indicate that the prone plank and the side plank mainly involve the oblique muscles, contrary to the isometric extension of the trunk that involves the multifidus. However, the results show a discrepancy with previous studies, an exacerbated activation was observed in all exercises of the right internal oblique and the left external oblique, a crossed pattern of synchronous activation that would reflect an adaptive behavior. For being a case report, this results are not conclusive, more research is needed in this regard.
... changes in muscle activity, kinematics, muscle properties, sensorimotor control, and performance) have been extensively examined in people with spinal pain as changes in these features may contribute to pain persistence or recurrence [6][7][8]. For example, adaptations in muscle activity, spine kinematics, and sensorimotor control have been reported in symptomatic people [9][10][11][12] and some studies suggest that these changes extend beyond the duration of a painful episode and could lead to potential long-term consequences, such as pain recurrence [13][14][15]. In support of this, current theories on pain and movement suggest that the new motor strategies which are adopted in the presence of pain could lead to suboptimal loading of the spine thereby contributing to persistent or recurrent symptoms [6][7][8]. ...
... Although affected by a very low quality of evidence, our findings are in accordance with those for people with chronic LBP [9,16], and with contemporary theories of motor adaptation to pain [10,14,15]. Motor behaviour changes are heterogenous across individuals but appear to have the common goal of protection in the short term [10,14,15]. ...
Article
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A plethora of evidence supports the existence of neuromuscular changes in people with chronic spinal pain (neck and low back pain), yet it is unclear whether neuromuscular adaptations persist for people with recurrent spinal pain when in a period of remission. This systematic review aimed to synthesise the evidence on neuromuscular adaptations in people with recurrent spinal pain during a period of remission. Electronic databases, grey literature, and key journals were searched from inception up to the 4th of September 2020. Eligibility criteria included observational studies investigating muscle activity, spine kinematics, muscle properties, sensorimotor control, and neuromuscular performance in adults (≥ 18 years) with recurrent spinal pain during a period of remission. Screening, data extraction, and quality assessment (Newcastle-Ottawa Scale) were conducted independently by two reviewers. Data synthesis was conducted per outcome domain. A meta-analysis with a random-effects model was performed where possible. The overall strength of evidence was rated using the Grading of Recommendations, Assessment, Development and Evaluation guidelines (GRADE). From 8292 records, 27 and five studies were included in a qualitative and quantitative synthesis, respectively. Very low level of evidence supports muscle activity changes in people with recurrent low back pain, especially greater co-contraction, redistribution of muscle activity, and delayed postural control of deeper trunk muscles. Reduced range of motion of the lumbar spine was also found. Meaningful conclusions regarding other outcome domains or people with recurrent neck pain could not be drawn. In conclusion, people with recurrent low back pain during a period of remission show muscle activity and spine kinematics adaptations. Future research should investigate the long-term impact of these changes, as well as adaptations in people with recurrent neck pain.
... Van Dieen et al. reported that the changed trunk muscle recruitment patterns in patients with low back pain enhance the stability of the lumbar spine [37]. These findings indicate the potential compensatory mechanisms of the active motion system in case of a resulting segmental instability and may partially explain why some patients gain enough passive stability to compensate after kyphoplasty and others do not. ...
Article
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Background: The objective of our study was to biomechanically evaluate the use of kyphoplasty to stabilize post-traumatic segmental instability in incomplete burst fractures of the vertebrae. Methods: The study was performed on 14 osteoporotic spine postmortem samples (Th11–L3). First, acquisition of the native multisegmental kinematics in our robot-based spine tester with three-dimensional motion analysis was set as a baseline for each sample. Then, an incomplete burst fracture was generated in the vertebral body L1 with renewed kinematic testing. After subsequent kyphoplasty was performed on the fractured vertebral body, primary stability was examined again. Results: Initially, a significant increase in the range of motion after incomplete burst fracture generation in all three directions of motion (extension–flexion, lateral tilt, axial rotation) was detected as proof of post-traumatic instability. There were no significant changes to the native state in the adjacent segments. Radiologically, a significant loss of height in the fractured vertebral body was also shown. Traumatic instability was significantly reduced by kyphoplasty. However, native kinematics were not restored. Conclusions: Although post-traumatic segmental instability was significantly reduced by kyphoplasty in our in vitro model, native kinematics could not be reconstructed, and significant instability remained.
... The moment in sagittal plane of the lumbar is decreased, which may be a compensatory protective mechanism to protect the painful tissues in the waist and back and enhance the stability of the trunk during activity. The decrease of lumbar moment may be related to the "pain-spasm-pain" mode (van Dieen et al., 2003). The occurrence of LBP can cause the cocontraction of the prime mover and antagonist muscles in the waist, and the contraction of the antagonist muscles can lead to the decrease of muscle moment in that area. ...
Article
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Low back pain (LBP) is one of the most prevalent and disabling disease worldwide. However, the specific biomechanical changes due to LBP are still controversial. The purpose of this study was to estimate the lumbar and lower limb kinematics, lumbar moments and loads, muscle forces and activation during walking in healthy adults and LBP. A total of 18 healthy controls and 19 patients with chronic LBP were tested for walking at a comfortable speed. The kinematic and dynamic data of the subjects were collected by 3D motion capture system and force plates respectively, and then the motion simulation was performed by OpenSim. The OpenSim musculoskeletal model was used to calculate lumbar, hip, knee and ankle joint angle variations, lumbar moments and loads, muscle forces and activation of eight major lumbar muscles. In our results, significant lower lumbar axial rotation angle, lumbar flexion/extension and axial rotation moments, as well as the muscle forces of the four muscles and muscle activation of two muscles were found in patients with LBP than those of the healthy controls ( p < 0.05). This study may help providing theoretical support for the evaluation and rehabilitation treatment intervention of patients with LBP.
... Compressive forces in the intervertebral disc have been associated with low back pain (22). It is also recognized that the compressive forces of the lumbar spine are increased during the abdominal muscle contraction (23). If we interpret that during a regular core-exercise or a regular daily activity the abdominal muscle should be activated, as a natural effect of the task requirements, and if we impose an extra level of contraction through conscious activation of any specific core muscle, we might be putting an extra level of compression in the spine. ...
Article
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Objective: The goal of this article is to compile relevant literature that proposes that perhaps the abdominal drawing-in maneuver (ADIM), also known as the “abdominal hollowing maneuver” (AHM), should not be applied as a general rule during the core training. Methods and Materials: Based on current evidence, this paper evaluates whether general use of this ADIM is beneficial for the core training. In this regard, we have searched for related scientific evidence in PubMed and Google Scholar. The keywords used were: abdominal hollowing maneuver, abdominal drawing-in maneuver, lumbo-pelvic stability, core stability. Results: The literature shows us that the application of ADIM during core strengthening exercises does not meet the requirements for isolated TrA-specific retraining, can increase Inter-Rectus Distance, may be incompatible with postural stability goals, and could interfere the Rectus Abdominis input impairing the lumbo-pelvic stability during high-load exercises. Conclusion: It can be concluded that if the goal is to train core stability and strength with high-load scenarios we should not use the ADIM.
... Effectively, more activation of the abdominals (and less back muscle) is required in this more extended position to ensure equilibrium. This also impacted the corresponding moderately-aggregated model outcomes, especially the ratio of abdominal to back muscle forces ( = 0.599), which highlights the level of trunk muscles co-contraction (van Dieen et al., 2003;van Dieen et al., 2017). These systematic effects were well emphasized in the present standing upright lifting tasks. ...
... Increased activation of the superficial lumbar musculature has indeed been observed in patients having CLBP versus healthy controls [35,36] as a compensating approach to enhance spinal stabilization, resulting in spinal muscle fatigue [37,38]. The absence of fatigue asymmetry (apart from the initial 5 s median frequency), especially of the median frequency slope between the left and right sides in athletes in the present study indicates equal amounts of higher activity of the lumbar multifidus on the left and right sides or this could be due to atrophy of the bilateral lumbar multifidus found in CLBP [39]. ...
Article
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Aim Chronic low back pain (CLBP) patients tend to have decreased back extensor muscle endurance resulting in lumbar muscle fatigability. Lumbar muscle fatigability investigations done on the general population have shown conflicting results; therefore, this study aimed to explore if there exists a fatigue asymmetry between the left and right sides and between the pain score classifications in university athletes with CLBP. Methods Twenty male athletes (Age: 22.95 ± 2.37 years) having CLBP were recruited. The athletes performed the Sorensen test and surface electromyography (sEMG) of bilateral multifidus was recorded simultaneously. The slope of linear regression of median frequency, and the median frequency of the initial and last 5 s were used to depict fatigability. The absolute differences between the right and left sides were used to compute asymmetry. Results The results demonstrated no asymmetry between the sides (p > 0.05), except for the initial 5 s median frequency (p < 0.05). There was no significant difference between the left and right sides when grouped according to the pain scores. Conclusions Athletes with CLBP demonstrate an absence of asymmetry in the fatigue characteristics of the multifidus, except for the initial 5 s median frequency. Practitioners assessing and treating CLBP in athletes can use this information while assessing and tailoring interventions for athletes.
... Many factors, such as fiber-type composition, contraction velocity and muscle length, are determinants of the mechanical muscle output and thus the measured SEMG signal. Therefore the functional aspects of muscles, such as fatigue [1,2], muscle co-ordination [3][4][5], or muscle recruitment [6][7][8], can be quantitatively reflected by SEMG. ...
Article
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Previous data suggest a correlation between the cross-sectional area of Type II muscle fibers and the degree of non-linearity of the EMG amplitude–force relationship (AFR). In this study we investigated whether the AFR of back muscles could be altered systematically by using different training modalities. We investigated 38 healthy male subjects (aged 19–31 years) who regularly performed either strength or endurance training (ST and ET, n = 13 each) or were physically inactive (controls (C), n = 12). Graded submaximal forces on the back were applied by defined forward tilts in a full-body training device. Surface EMG was measured utilizing a monopolar 4 × 4 quadratic electrode scheme in the lower back area. The polynomial AFR slopes were determined. Between-group tests revealed significant differences for ET vs. ST and C vs. ST comparisons at the medial and caudal electrode positions, but not for ET vs. C. Further, systematic main effects of the “electrode position” could be proven for ET and C groups with decreasing x2 coefficients from cranial to caudal and lateral to medial. For ST, there was no systematic main effect of the “electrode position”. The results point towards training-related changes to the fiber-type composition of muscles in the strength-trained participants, particularly for their paravertebral region.
... In the case of a decrease in core stability, biarticular muscle dysfunction causes overactivity of multijoint muscles, which can cause traumatic injury 33) . The erector spinae muscles become overactive to compensate for decreased spinal stability 34) . Here, the gluteus medius and erector spinae muscles during trunk rotation had significantly higher muscle activity in the group with disc degeneration, suggesting overactivity due to a decrease in core stability. ...
Article
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Lower back pain (LBP) is common among baseball players, and the occurrence of lumbar intervertebral disc degeneration is high. The dynamic load on the lumbar spine due to the postures and movements characteristic of baseball is suspected of aggravating LBP caused by degeneration, but the difference in batting action between players with and without degeneration is not known. The purpose of this study was to investigate the difference in batting motion in the presence and absence of lumbar disc degeneration (LDD). The subjects were 18 male baseball players belonging to the University League Division I: seven with disc degeneration and 11 without. The motion task analyzed tee batting. The items examined were the angles of rotation of shoulder, pelvis, hip, and twisting motion; rotation angular velocity; time to maximum angular velocity; and muscle activity potentials of the bilateral latissimus dorsi, erector spinae, multifidus, external oblique, internal oblique, rectus abdominis, and gluteus medius muscles; at each stage of batting action. There were significant differences between the shoulder and pelvis in rotation angle, time to maximum angular velocity, and muscle activity in the presence and absence of LDD, and in the time to maximum angular velocity between the shoulder and pelvis. We infer that these differences are characteristic of batting motion due to LDD.
... These limitations are partially explained by biopsychosocial changes in individuals with LBP that modify how they interact with the world. 4,[9][10][11][12][13][14][15][16][17][18][19][20][21][22] ...
Article
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Objective: Biomechanics represents the common final output through which all biopsychosocial constructs of back pain must pass, making it a rich target for phenotyping. To exploit this feature, several sites within the NIH Back Pain Consortium (BACPAC) have developed biomechanics measurement and phenotyping tools. The overall aims of this paper were to: 1) provide a narrative review of biomechanics as a phenotyping tool; 2) describe the diverse array of tools and outcome measures that exist within BACPAC; and 3) highlight how leveraging these technologies with the other data collected within BACPAC may elucidate the relationship between biomechanics and other metrics used to characterize low back pain (LBP). Methods: The narrative review highlights how biomechanical outcomes can discriminate between those with and without LBP, as well as the severity of LBP. It also addresses how biomechanical outcomes track with functional improvements in LBP. Additionally, we present the clinical use case for biomechanical outcome measures that can be met via emerging technologies. Results: To answer the need of measuring biomechanical performance our results section describes the spectrum of technologies that have been developed and are being used within BACPAC. Conclusion: and future directions: The outcome measures collected by these technologies will be an integral part of longitudinal and cross-sectional studies conducted in BACPAC. Linking these measures with other biopsychosocial data collected within BACPAC increases our potential to use biomechanics as a tool for understanding the mechanisms of LBP, phenotyping unique LBP subgroups, and matching these individuals with an appropriate treatment paradigm.
... night pain, unexplained weight loss) [17]. The control group consisted of 15 participants who had never experienced back pain with a duration longer than 3 consecutive days [31]. They were matched with the LBP group for gender, age and body mass index. ...
Article
Background For people above 65 years old, low-back pain (LBP) is associated with balance problems and falls. Down-weighting of proprioception due to ageing and LBP may cause such balance problems. While lumbar proprioceptive deficits have been shown in LBP and indications for more generalized deficits have been found, ankle proprioception, which is crucial for balance control, has not been studied in people with LBP. Research question Is there any difference in ankle proprioceptive acuity between community-dwelling older adults with and without LBP? We hypothesized that ankle proprioception was impaired in community-dwelling older adults with LBP compared to those without LBP. Methods Thirty participants over 65 years old volunteered. Fifteen had LBP (M/F = 2/13, age = 72.0 (4.6) years), fifteen were healthy controls without back pain (control group) (M/F = 2/13, age = 72.1 (4.8) years). Ankle proprioception was measured in normal weight-bearing conditions, using the Active Movement Extent Discrimination Apparatus (AMEDA). Accuracy on the ankle proprioceptive test was expressed as absolute error (AE), constant error (CE) and variable error (VE). Results AE was significantly larger (P = 0.029, 95% CI = [0.00, 0.90]) in the LBP group, CE was also significantly larger (P = 0.046, 95% CI = [-0.91, -0.01]), indicating an underestimation of ankle inversion in participants with LBP compared to controls. VE was not different between the two groups (P = 0.520, 95% CI = [-0.20, 0.59]). No significant correlation was found between pain intensity and AE, CE or VE (P > 0.05). Conclusion Ankle proprioception decreased in older people with LBP compared to healthy peers, suggesting impaired central proprioceptive processing. Older people with LBP underestimate the extent of ankle inversion, which may increase fall risk. Thus, evaluation and training of ankle proprioception may be useful in older people with LBP.
... The basic premise of this landmark theoretical hypothesis is that the neural element is a regulating step in this stabilizing system [1,[4][5][6]. The neural reflex of peripheral sensory system, represented by vestibular system and muscle-tendon proprioceptors, does attempt to control muscles dynamics during head-neck movements [7][8][9][10][11]. The sensory information from the vestibular system is responsible for providing the brain with motion, head position, and spatial orientation, it is also involved with motor functions that keep balance, stabilize head-neck during movement, and maintain posture [12,13]. ...
Article
Background and objective Neural reflex is hypothesized as a regulating step in spine stabilizing system. However, neural reflex control is still in its infancy to consider in the previous finite element analysis of head-neck system for various applications. The purpose of this study is to investigate the influences of neural reflex control on neck biomechanical responses, then provide a new way to achieve an accurate biomechanical analysis for head-neck system with a finite element model. Methods A new FE head-neck model with detailed active muscles and spinal cord modeling was established and globally validated at multi-levels. Then, it was coupled with our previously developed neuromuscular head-neck model to analyze the effects of vestibular and proprioceptive reflexes on biomechanical responses of head-neck system in a typical spinal injury loading condition (whiplash). The obtained effects were further analyzed by comparing a review of epidemiologic data on cervical spine injury situations. Result The results showed that the active model (AM) with neural reflex control obviously presented both rational head-neck kinematics and tissue injury risk referring to the previous experimental and epidemiologic studies, when compared with the passive model (PM) without it. Tissue load concentration locations as well as stress/strain levels were both changed due to the muscle activation forces caused by neural reflex control during the whole loading process. For the bony structures, the AM showed a peak stress level accounting for only about 25% of the PM. For the discs, the stress concentrated location was transferred from C2-C6 in the PM to C4-C6 in the AM. For the spinal cord, the strain concentrated locations were transferred from C1 segment to around C4 segment when the effects of neural reflex control were implemented, while the grey matter and white matter peak strains were reduced to 1/3 and 1/2 of the PM, respectively. All these were well correlated with epidemiological studies on clinical cervical spine injuries. Conclusion In summary, the present work demonstrated necessity of considering neural reflex in FE analysis of a head-neck system as well as our model biofidelity. Overall results also verified the previous hypothesis and further quantitatively indicated that the muscle activation caused by neural reflex is providing a protection for the neck in impact loading by decreasing the strain level and changing the possible injury to lower spinal cord level to reduce injury severity.
... The seven muscles examined were: left and right rectus abdominus (RA), internal oblique (IO), tensor fascia latae (TFL), lumbar erector spinae (LES), lumbar multifidus (MUL), gluteus maximus (Gmax) and biceps femoris (BF). These muscles were chosen to be studied because of their functional roles as the prime movers and/or stabilisers of the lumbopelvic region during flexion (standing to end of bending) and extension (end of bending to standing) phases of the task [33,34]. Standardized skin preparation was applied to achieve the skin impedance <10 kO for EMG electrode placement [35]. ...
Article
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This study aims to investigate the dysfunction and recovery of the lumbopelvic movement and motor control of people with chronic nonspecific low back pain after a structured rehabilitation which emphasizes on re-education and training of movement and motor control. The lumbopelvic movement and motor control pattern of 30 adults (15 with chronic low back pain, 15 healthy controls) were assessed using 3D motion and electromyographic analysis during the repeated forward bending test, in additional to the clinical outcome measures. Regional kinematics and muscle recruitment pattern of the symptomatic group was analysed before and after the 6-week rehabilitation, and compared to healthy controls. Significant improvement in back pain, functional capacity and self-efficacy of the symptomatic group was found after the rehabilitation. Patients with chronic nonspecific low back pain were capable to recover to a comparable level of the healthy controls in terms of their lumbopelvic movement and motor control pattern upon completion of a 6-week rehabilitation program, despite their dysfunction displayed at baseline. Phase specific motor control reorganization in which more profound and positive changes shown during the flexion phase. Our findings indicate that the recovery of the movement and motor control pattern in patients with chronic low back pain achieved to a comparable level of the healthy able-bodies. The improvement of both the physical outcome measures suggest that specific rehabilitation program which emphasizes on optimizing motor control during movements would help promoting the functional recovery of this specific low back pain subgroup.
... Aktivnost mišića je neophodna da bi se zadržao položaj pasivne stabilnosti. Mišići centralnog dijela trupa kroz procese ko-kontrakcije najviše doprinose procesu aktivnog održavanja stabilnosti cijelog tijela (van Dieën, Cholewicki, & Radebold, 2003). Proces ko-kontrakcija se kod odraslih osoba dešava kada se detektuje pokret koji može da izazove povredu kičmenog stuba putem mehanoreceptora i receptora boli. ...
Thesis
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Abstract Aim of the study was to experimentally validate and determine the effects of 8 - week additional motor control exercise (MCE) based like exercise program on body composition, body posture and some motor abilities. Sample was randomized from football in experimental group 1 (Ex1, n=12; mean (SD): 10.5 (0.5) yrs; 148 (5.4) cm; 39.6 (5.4) kg i 18.04 (1.9) kg/m2) and control group 1 (Kon1, n=11; 10.36 (0.5) yrs; 144 (6.2) cm; 37.9 (5.6) kg i 18.27 (2.1) kg/m2), from karate to experimental group 2 (Ex2, n=11; 12.2 (1.4) yrs; 158.1 (6.2) cm; 46.6 (7.15) kg and 18.63 (2.65) kg/m2) and control group 2 (Kon2, n=10; 11.8 (1.5) yrs; 155.4 (8.97) cm; 48.23 (13.5) kg i 19.6 (3.6) kg/m2) and from athletics to experimental group 3 (Ex3, n=13; 12.15 (1.2) yrs; 145 (6.17) cm; 41.54 (5.02) kg i 19.7 (2.2) kg/m2) and control group 3 (Kon3, n=10; 12.2 (0.9) yrs; 145.5 (6.0) cm; 44.25 (6.54) kg i 21.14 (2.26) kg/m2). Program with average attendance frequency of 2-3 times/week with duration of 20-30 minutes had large effect on Ex1 for overall stability index (OSI, (ES=-0.84; -26%,)), anterior – posterior stability (APSI, (ES=-0.73; -22%)) and flamingo test (ES=1.00; +105%) along with moderate effect on medial – lateral stability (MLSI, (ES=-0.73, -21%)). Ex2 significantly improved OSI (Large effect, ES=-1.22; -27%), and agility (T-test (Large effect, ES=-1.28; -3%)), along with moderate effect on APSI (ES=-0.63; -9%) and MLSI (ES=-0.60 -21%). Small effect was observed for flamingo test (ES=0.21; +28%) and 20 meters sprint (T20m, ES=-0.37; -1%). Ex3 significantly reduced percentage of relative body fat (Small effect, ES=-0.27; 0.2%). No significant changes were observed for the control groups. Results suggested that strength training of core muscles, based on motor control learning to induce changes in contraction intensity, can improve dynamic and static stability in young athletes. Adaptation on the exercise program indirectly improved stability and balance by reducing the latent time to muscle contraction by improving intramuscular coordination of the deep trunk muscles which improved maintaining of optimal body position during stability tasks. Programs with exercises intended to strengthen trunk and spine stabilization muscles, when additionally performed, can improve stability and prevent injuries. Exercise program did not significantly affect nor improved body composition, body posture, flexibility (sit and reach), sprinting performance (T20m), agility (T-test) and power (CMJ). Keywords: Body composition, motor control, postural control, stability
... Besides the role of psychosocial aspects in persistent pain [3,4], clinical evidence has revealed extensive changes in neuromuscular control in people with pain, during both acute and chronic stages [5][6][7][8][9]. Current theories suggest a strong relationship between pain and movement, implicating changes in response to pain at multiple levels of the neuromuscular system [1,10,11]. ...
Article
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Background Numerous studies report changes in neuromuscular control in people with low back pain (LBP). However, the relationship between pain and altered neuromuscular control is challenging to unravel given the heterogeneity that exists in clinical populations. One approach commonly adopted to overcome this issue is the use of experimental pain models, but it is currently unclear if the effects of experimental pain are consistent between studies. Therefore, this planned study will systematically evaluate and summarise the effect of experimentally induced pain in the lumbar region on neuromuscular control at sites both locally and remote to the low back. Methods This protocol has been developed following the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P). MEDLINE, EMBASE, CINAHL, ZETOC, Web of Science, and grey literature will be searched up to August 31, 2021. Screening processes (title/abstract and full-text), data extraction, and risk of bias assessment will be conducted by two independent reviewers. Studies investigating the effects of exogenous pain models delivered to the low back region on neuromuscular control in healthy individuals will be included. Muscle activity and body kinematics will be the outcomes of interest. The comparisons of interest will be between baseline or control conditions and the experimental pain condition, as well as between the experimental pain and post-pain conditions. Randomised crossover and non-randomised studies of interventions will be included and their risk of bias will be evaluated with the Cochrane Risk-of-Bias tool or with the Risk Of Bias In Non-randomised Studies of Interventions tool, respectively. A random-effect meta-analysis will be conducted for quantitative synthesis when clinical and methodological consistency is ensured. Quality of evidence will be evaluated using the Grading of Recommendations, Assessment, Development and Evaluation guidelines. Discussion The current review will provide new insights to understand if and what neuromuscular adaptations are caused by pain experimentally induced in the lumbar region. Our findings will reveal which experimental pain model is able to better reproduce adaptations similar to those identified in people with low back pain, possibly contributing to improving our understanding of motor adaptation to low back pain in the long term. Systematic review registration PROSPERO CRD42020220130
... Since Panjabi rstly suggested the stabilizing system of spine: instability hypothesis of low back pain [5], people focus on studying the function of trunk muscle of the patients. Lumbar paraspinal muscle (LPM) such as erector spinae muscle, lumbar multi dus and transversus abdominis were found to be important for core stabilization [6]. ...
Preprint
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Background Non-specific chronic low back pain (NSCLBP) is a multifactor disorder with high prevalence rate of people all around the world. Lumbar paraspinal muscle (LPM) plays an important role of spine stabilization. However, the electrical properties of LPM in the patients were unclear. Aim to explore the electrical properties of bilateral LPM between patients with NSCLBP and healthy controls (HC), the study was designed to applied electrical impedance myography (EIM) technique to measure the LPM.MethodsA total of thirty participates (15 in NSCLBP group, 15 in HC group) were instructed to have each side of LPM measured at the rest state and the maximum volunteer contraction (MVC) state. Then measured the EIM parameters of LPM at L4/5 level by a multi-frequency device. Each measurement repeated three times. The EIM parameters at 50 kHz, 100 kHz, 200 kHz current frequencies were enrolled into the statistical analysis.ResultsAt the three current frequencies, parameters in the right side of LPM had not significantly difference from the left ( P >0.05, respectively). Resistance (R) of LPM in NSCLBP group was larger than that in HC group ( P <0.05, respectively), phase angle (PA) in NSCLBP group was smaller than that in HC group ( P <0.05, respectively) and there was no difference of the reactance value between the two groups ( P >0.05, respectively). At 50 kHz, relationships between the EIM parameters and geometric parameters of LPM were not significant in NSCLBP group or HC group ( P >0.05, respectively).Conclusion The electrical properties of bilateral LPM in young adults with NSCLBP were different from those of healthy individuals regardless of any current frequency. The ultrasound parameters of LPM, however, showed no significant difference between young patients with NSCLBP and healthy participants. EIM measurement might be more sensitive than rehabilitative ultrasound for NSCLBP in young adults.Trial registrationThe Chinese Clinical trial registration number: ChiCTR2100043113.
... Patients with LBP have been reported to display changed neuromuscular activity such as delayed local muscle activation and greater co-contraction of the abdominal and back muscles [4][5][6][7]. Some studies suggest that these changes extend beyond the duration of a painful episode and could lead to long-term consequences [8,9], as the pain may recur due to the increased loading of the spine [10,11]. ...
Article
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Abstract Background The active hip abduction test (AHAbd) is widely used to evaluate lumbopelvic stability, but the onset of trunk muscle activation during the test in individuals with recurrent low back pain (rLBP) has not been investigated so far. It is important to investigate the pattern of trunk muscle activation during the AHAbd test to provide insight into the interpretation of observation-based assessment results; this may help to create exercise therapy interventions, from a movement control perspective, for people seeking treatment for rLBP. The purpose of this study was to compare the timing of trunk muscle activation between individuals with and without rLBP and to assess potential differences. Methods Seventeen subjects in remission from rLBP and 17 subjects without rLBP were recruited. We performed surface electromyography of the transversus abdominis/internal abdominal oblique, external oblique, erector spinae, and gluteus medius muscles during the AHAbd test on both sides. The onset of trunk muscle activation was calculated relative to the prime mover gluteus medius. The independent-samples t- and Mann-Whitney U tests were used to compare the onset of trunk muscle activation between the two groups. Results The onset of transversus abdominis/internal abdominal oblique activation on the ipsilateral (right AHAbd: −3.0 ± 16.2 vs. 36.3 ± 20.0 msec, left AHAbd: −7.2 ± 18.6 vs. 29.6 ± 44.3 ms) and contralateral sides (right AHAbd: −11.5 ± 13.9 vs. 24.4 ± 32.3 ms, left AHAbd: −10.1 ± 12.5 vs. 23.3 ± 17.2 ms) and erector spinae on the contralateral side (right AHAbd: 76.1 ± 84.9 vs. 183.9 ± 114.6 ms, left AHAbd: 60.7 ± 70.5 vs. 133.9 ± 98.6 ms) occurred significantly later in individuals with rLBP than in individuals without rLBP (p
... Sufficient LMM function is essential to maintain the stability of the kinetic chain and generate forces to the lower and upper limbs [4]. Magnetic resonance imaging (MRI) and ultrasound imaging studies of athletes and non-athletes with LBP have reported morphological changes and functional deficits of the LMM, such as LMM atrophy [5][6][7][8][9], LMM cross-sectional area (CSA) asymmetry [5,7,[10][11][12], increased fatty infiltration [13][14][15][16], and increased or decreased muscle activity [17][18][19]. Magnetic resonance imaging (MRI) remains the gold standard technique for muscle imaging, since the high resolution allows accurate assessment of muscle size and composition. However, ultrasound imaging is a more accessible and less expensive imaging technique that provides valuable information about muscle function [20][21][22]. ...
Article
Full-text available
Background and Objectives: Ultrasound echo intensity (EI) of the lumbar multifidus muscle (LMM) could offer valuable insights regarding muscle quality in people with low back pain (LBP). However, whether the rater’s experience noticeably influences the reliability and precision of LMM EI measurements has not been established. The aims of this study were to investigate the intra-rater and inter-rater reliability of LMM EI measurements, and to compare the reliability and SEM between a novice and an experienced rater. Materials and Methods: Twenty athletes (10 females, 10 males) with a history of LBP were included in this study. Transverse ultrasound images of LMM were taken at L5 in prone. LMM EI measurements were obtained bilaterally by tracing the maximum ROI representing the LMM cross-sectional area (CSA), avoiding the inclusion of bone or surrounding fascia. All measurements were performed by two novice raters and an experienced researcher. Each measurement was acquired by each rater three times for each side on three different images, and the average was used in the analyses. Raters were blinded to each other’s measurements and the participant’s clinical information. Intra-class correlation coefficients (ICCs) were obtained to assess the intra-rater and inter-rater reliability. Results: The intra-rater ICC values for the LMM measurements for the experienced rater were excellent (ICC all > 0.997). The inter-rater reliability ICC values showed moderate to excellent reliability (0.614 to 0.994) and agreement between the novice raters and the experienced rater, except for Novice 1 for the right LMM, which revealed lower ICCs and a wider 95% CI. Intra-rater and inter-rater reliability results were similar when separately looking at the right and left side of the muscle and participant gender. Conclusions: Our findings support the clinical use of ultrasound imaging for the assessment of LMM EI in individuals with LBP.
... Because of the similar function, this pair of muscles acts similarly to the erector spinae (longissimus) and the rectus abdominis, with higher CoI during the explosive ascending phase. These results provide more information on the joint activation of muscles that act as both agonist and antagonist during trunk effort, with and without counting the additional resistance moment that must be overcome due to the joint activation of the muscles [17,18]. ...
Article
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The purpose of this study was to determine the muscle activation and co-activation of selected muscles during the kettlebell single arm swing exercise. To the best of our knowledge, this is the first study investigating the muscle co-activation of a kettlebell single arm swing exercise. Nine volunteers participated in the present study (age: 22.6 ± 3.8 years; body mass: 80.4 ± 9.2 kg; height: 175.6 ± 7.5 cm). The electrical muscle activity of eight right agonist/antagonist muscles (AD/PD, ESL/RA, ESI/EO, and GM/RF) were recorded using a surface EMG system (Myon m320RX; Myon, Switzerland) and processed using the integrated EMG to calculate a co-activation index (CoI) for the ascending and descending phases. A significant effect of the ascending and descending phases on the muscles’ CoI was observed. Post hoc analyses showed that the co-activation was significantly higher in the descending phase compared to that in the ascending phase of AD/PD CoI (34.25 ± 18.03% and 24.75 ± 13.03%, p < 0.001), ESL/RA CoI (34.97 ± 17.86% and 24.19 ± 10.32%, p < 0.001), ESI/EO CoI (41.14 ± 10.72% and 30.87 ± 11.26%, p < 0.001), and GM/RF CoI (27.49 ± 12.97% and 34.98 ± 14.97%, p < 0.001). In conclusion, the co-activation of the shoulder muscles varies within the kettlebell single arm swing. The highest level of co-activation was observed in the descending phase of AD/PD and GM/RF CoI, and the lowest level of co-activation was observed during the descending phase, ESL/RA and ESI/EO CoI. In addition, the highest level of co-activation was observed in the ascending phase of ESL/RA and ESI/EO CoI, and the lowest level of co-activation was observed during the ascending phase, AD/PD and GM/RF CoI. The co-activation index could be a useful method for the interpretation of the shoulder and core muscles’ co-activity during a kettlebell single arm swing.
Article
Introduction: Thoracic mobilization and tissue release are common manual techniques in clinical practice. However, the relative effects of these two treatments on chronic low back pain (CLBP) have not yet been explored. Thus, this study aimed to investigate and compare the immediate effects of thoracic mobilization with those of soft tissue release on trunk movement, pain sensation, and muscle activity in patients with CLBP. Methods: 28 participants were randomly assigned to two intervention groups. The mobilization group received mobilization treatment at the hypomobile joints of the trunk segment, while the soft tissue release group received thoracolumbar fascia release and massage in the lumbar region. The trunk range of motion (ROM), tissue hardness, pressure pain threshold (PPT), and erector spinae activity during light-weight lifting tasks were measured before and immediately after both interventions. Findings: All measured outcomes in both groups improved after intervention (p < 0.05). The mobilization technique significantly improved side bending and rotation, PPT, and tissue hardness compared to soft tissue release. However, lumbar muscle activation reduced to a greater extent in the soft-tissue release group. Conclusion: Both techniques improved trunk ROM and PPT and reduced tissue hardness and muscle activation. Therefore, both these techniques are recommended for patients with CLBP.
Article
BACKGROUND CONTEXT Trunk postural control differs between individuals with and without chronic low back pain. Whether this corresponds to differences in hip/spine coordination during the early acute phase of LBP (ALBP) is unclear. PURPOSE To compare hip/spine coordination in relation to seat movements between individuals with and without ALBP when balancing on an unstable seat and to identify coordination strategies to maintain balance using cluster analysis. STUDY DESIGN/SETTING Cross-sectional observational study. PATIENT SAMPLE ALBP (n=130) and pain-free (n=72) individuals. OUTCOME MEASURES Frequency domain measures to evaluate hip/spine coordination (amplitude spectrum, phase angle, coherence) and time-series measures to assess overall balance performance (centre of pressure [CoP] reflecting the amount of seat movements, upper thorax motion as a surrogate for head motion). METHODS Participants maintained balance while sitting on a seat fixed to a hemisphere. Seat, hip and spine (lower lumbar, lumbar, upper lumbar, thoracic) angular motion and force plate data were recorded. RESULTS Overall, seat/CoP movements (amplitude spectrum and RMSdisplacement) were greater (in both planes) and sagittal coordination (coherence) between the hip or lower spine and seat movements was lower in ALBP than controls. Cluster analysis using coherence data revealed different coordination strategies to maintain balance. Separate clusters used a “lower lumbar strategy” and “hip strategy” in the sagittal plane, and a “lower and upper lumbar strategy” and “lower lumbar strategy” in the frontal plane. A cluster using a “low coherence strategy” in both planes was also identified. CONCLUSIONS Hip and lower spine coordination was less in individuals with ALBP in conjunction with a lower quality of overall balance performance. However, interpretation of the relationship between coherence and overall balance performance was not straightforward. Clusters in both the ALBP group and the control group adopted a low coherence strategy, and this was not consistently related to poor overall balance performance. This suggests overall balance performance cannot be inferred from coherence alone and requires consideration of interaction of other different features.
Article
Background: Understanding postural control in low back pain (LBP) subgroups can help develop targeted interventions to improve postural control. The studies on this topic are limited. Therefore, the primary purpose of this study was to compare the postural control of LBP subgroups with healthy individuals during overhead load lifting and lowering. Methods: In this cross-sectional study, the participants were 52 with LBP and 20 healthy. The LBP patients were classified based on the O'Sullivan classification system into 21 flexion patterns and 31 active extension patterns. The participants lifted the box from their waists to their overheads and lowered it to their waists. Changes in postural control parameters were measured with a force plate system. Results: The results of the analysis of variance showed that during load lifting, the mediolateral phase plane (p = .044) and the mean total velocity (p = .029) had significant differences between flexion patterns and healthy. Also, the load-lowering results showed that active extension patterns, compared with healthy, had significant differences in the anteroposterior-mediolateral phase plane (p = .042). The patients showed less postural sway than the healthy. Conclusions: The results in this work highlight the importance of identifying the homogenous subgroups in LBP and support the classification of heterogeneous LBP. Different subgroups exhibit different postural control behaviors. These behaviors can be due to the loading of various tissues during different tasks.
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Low back pain is associated with changes in trunk muscle structure and function and motor control impairments. Voluntary force modulation (FM) of trunk muscles is a unique and under-investigated motor control characteristic. One of the reasons for this paucity of evidence is the lack of exploration and publication on the reliability and validity of trunk FM protocols. The purpose of this study was to determine the within- and between-day test-retest reliability and construct validity for trunk extensor muscle FM. Twenty-nine healthy participants were tested under three FM conditions with different modulation rates. Testing was performed on a custom-built apparatus designed for trunk isometric force testing. FM accuracy relative to a fluctuating target force (20–50%MVF) was quantified using the root mean square error of the participant’s generated force relative to the target force. Reliability and precision of measurement were assessed using the Intraclass Correlation Coefficient (ICC), standard error of measurement (SEM), minimal detectable difference (MDD95), and Bland-Altman plots. In a subset of participants, we collected surface electromyography of trunk and hip muscles. We used non-negative matrix factorization (NNMF) to identify the underlying motor control strategies. Within- and between-day test-retest reliability was excellent for FM accuracy across the three conditions (ICC range: 0.865 to 0.979). SEM values ranged 0.9–1.8 Newtons(N) and MDD95 ranged from 2.4–4.9N. Conditions with faster rates of FM had higher ICCs. NNMF analysis revealed two muscle synergies that were consistent across participants and conditions. These synergies demonstrate that the muscles primarily involved in this FM task were indeed the trunk extensor muscles. This protocol can consistently measure FM accuracy within and between testing sessions. Trunk extensor FM, as measured by this protocol, is not specific to any trunk muscle group but is the result of modulation by all the trunk extensor muscles.
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Background and Aims People suffer from neck pain, headache, kyphosis and back pain while working with the computer for a long time, which seems to increase day by day with the advancement of technology. The present study aims to investigate the effect of two types of thoracolumbosacral braces (with and without sensors) on electromyography activity of selected muscles in people with thoracic kyphosis during typing. Methods In this quasi-experimental study, 15 males with thoracic kyphosis volunteered to participate in the study. Subjects performed typing task for one minute at three conditions (with no brace, with a simple brace, and with a brace having sensors). An 8-channel wireless electromyography system was used to record the activity of selected muscles in the upper limb and shoulder area. Repeated measures analysis of variance was used to compare the electrical activity of muscles between different conditions. The significance level was set at 0.05. Results The median frequency of trapezius muscle was significantly lower while using the brace with sensors compared to that without using brace (P=0.005). In median frequency of other muscles, no significant differences were observed among three conditions (P>0.05). Conclusion The use of thoracolumbosacral brace with sensors can reduce the median frequency of trapezius muscle in people with kyphosis. This reduction in median frequency may be related to the passive support of the brace. Reduction of electrical activity in trapezius muscle while using thoracolumbosacral brace can increase the time to reach fatigue.
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Background: Individualized exercise programs based on personal impairment could lead to successful rehabilitation. An effective way to train spine stability is to find exercises that take advantage of the synergistic relation between local and global stabilization systems. Objective: This study aimed to investigate synergistic relationship between the muscles of the local and global systems during three modified side bridge exercises compared with traditional side bridge (TSB). Methods: Twenty healthy participants performed TSB, both leg lift while side-lying (BLLS), torso lift on a 45∘ bench while side-lying (TLBS), and pelvic lift on side-lying (PLS) in random order. Surface electromyography data were analyzed. Results: The results indicate that PLS was effective as TSB on trunk muscle activity. However, BLLS and TLBS demonstrated significantly less rectus abdominal (RA) muscle activity compared to TSB (p< .001). Additionally, BLLS and TLBS had a higher internal oblique (IO)/RA muscle activity ratio than TSB (p< .001). Conclusions: PLS could be a suitable alternative exercise for individuals who are unable to perform TSB, as it can effectively activate trunk muscles. BLLS and TLBS may be appropriate for training the local stability system, while limiting activation of the RA.
Article
Background: We considered spinal segmental movement exercise that voluntarily control local muscles as a convenient treatment to correct the trunk muscle recruitment pattern in individuals with global muscle overactivity. The purpose of this study was to verify the effects of segmental flexion and extension movements of the spine and overall flexion and extension movements of the spinal column on the flexibility of the spinal column among healthy university students who had completed a day of lectures and had a certain load on their lower back as a preliminary step to applying the exercise to low back pain patients with a broken trunk muscle recruitment pattern. Methods: The subjects performed trunk flexion/extension exercises that required segmental control of the spine (segmental movement) and trunk flexion/extension exercises that do not require segmental control of the spine (total movement) in the chair position. As an evaluation task, finger floor distance (FFD) and muscle tension of the hamstrings were evaluated before and after exercise intervention. Results: There was no significant difference in the FFD value and the passive pressure before the intervention between the two exercises. FFD decreased significantly after the intervention compared to that before, and passive pressure did not change in both motor tasks. The FFD change amount of segmental movement was significantly larger than that of total movement. (P < 0.01). Conclusions: It has been suggested that segmental spinal movements improve spinal mobility and may reduce global muscle tension.
Article
Computational models have been used extensively to assess diseases and disabilities effects on musculoskeletal system dysfunction. In the current study, we developed a two degree-of-freedom subject-specific second-order task-specific arm model for characterizing upper-extremity function (UEF) to assess muscle dysfunction due to chronic obstructive pulmonary disease (COPD). Older adults (65 years or older) with and without COPD and healthy young control participants (18 to 30 years) were recruited. First, we evaluated the musculoskeletal arm model using electromyography (EMG) data. Second, we compared the computational musculoskeletal arm model parameters along with EMG-based time lag and kinematics parameters (such as elbow angular velocity) between participants. The developed model showed strong cross-correlation with EMG data for biceps (0.905, 0.915) and moderate cross-correlation for triceps (0.717, 0.672) within both fast and normal pace tasks among older adults with COPD. We also showed that parameters obtained from the musculoskeletal model were significantly different between COPD and healthy participants. On average, higher effect sizes were achieved for parameters obtained from the musculoskeletal model, especially for co-contraction measures (effect size = 1.650 ± 0.606, p < 0.001), which was the only parameter that showed significant differences between all pairwise comparisons across the three groups. These findings suggest that studying the muscle performance and co-contraction, may provide better information regarding neuromuscular deficiencies compared to kinematics data. The presented model has potential for assessing functional capacity and studying longitudinal outcomes in COPD.
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Purpose To establish intra- and inter-session reliability of high-density surface electromyography (HDEMG)-derived parameters from the thoracic erector spinae (ES) during static and dynamic goal-directed voluntary movements of the trunk, and during functional reaching tasks. Methods Twenty participants performed: 1) static trunk extension, 2) dynamic trunk forward and lateral flexion, and 3) multidirectional functional reaching tasks on two occasions separated by 7.5 ± 1.2 days. Muscle activity was recorded bilaterally from the thoracic ES. Root mean square (RMS), coordinates of the barycentre, mean frequency (MNF), and entropy were derived from the HDEMG signals. Reliability was determined with intraclass correlation coefficient (ICC), coefficient of variation, and standard error of measurement. Results Good-to-excellent intra-session reliability was found for all parameters and tasks (ICC: .79-.99), whereas inter-session reliability varied across tasks. Static tasks demonstrated higher reliability in most parameters compared to functional and dynamic tasks. Absolute RMS and MNF showed the highest overall reliability across tasks (ICC: .66-.98), while reliability of the barycentre was influenced by the direction of the movements. Conclusion RMS and MNF derived from HDEMG show consistent inter-session reliability in goal-directed voluntary movements of the trunk and reaching tasks, whereas the measures of the barycentre and entropy demonstrate task-dependent reliability.
Article
Persons with lower limb amputation (LLA) are at high risk for developing chronic low back pain (LBP), often with biomechanical factors considered as likely contributors. Here, trunk and pelvis kinematics, muscle forces, and resultant spinal loads were characterized in persons with LLA, with and without chronic LBP. Thirty-five persons with unilateral LLA – 19 with chronic LBP (“LLA-cLBP”), 16 without LBP (“LLA-nLBP”) – and 15 (uninjured) persons without LBP (“CTR-nLBP”) walked overground (1.3 m/s) while thorax and pelvis kinematics were tracked (and ranges of motion [ROM] computed), and used as inputs for a non-linear finite element model of the spine to estimate global and local muscle forces, and resultant spinal loads. In the frontal and transverse planes, thorax ROM were up to 66.6% smaller in LLA-nLBP versus LLA-cLBP (P < 0.001) and CTR-nLBP (P < 0.001). In the sagittal plane, pelvis ROM was 50.4% smaller in LLA-nLBP versus LLA-cLBP (P = 0.014). LLA-cLBP exhibited 45.5% and 34.2% greater peak local and global muscle forces, respectively, versus CTR-nLBP (P < 0.011). Up to 48.1% greater spinal loads were observed in LLA-cLBP versus CTR-nLBP (P < 0.013); peak compression and local muscle forces were respectively 20.2% and 41.0% larger in LLA-nLBP versus CTR-nLBP (P < 0.005). Despite differences in trunk and pelvis kinematics between LLA-cLBP and LLA-nLBP, trunk muscle forces and spinal loads were similar (P > 0.101) between these groups. Similar loading parameters regardless of LBP presence, while highly dependent on trunk muscle activation strategies, may mitigate further accumulation of mechanical fatigue. It remains important to understand the temporality of loading with respect to LBP onset following LLA.
Article
Low back pain (LBP) is frequently reported following rear impact collisions. Knowledge of how the facet joint capsule (FJC) mechanically behaves before and after rear impact collisions may help explain LBP development despite negative radiographic evidence of gross tissue failure. This study quantified the Green strain tensor in the facet joint capsule during rotation and translation range-of-motion tests completed before and following an in vitro simulation of a rear impact collision. Eight FSUs (4 C3-C4, 4 C5-C6) were tested. Following a preload test, FSUs were flexed and extended at 0.5 degrees/second until an ±8 Nm moment was achieved. Anterior and posterior joint translation was then applied at 0.2 mm/s until a target ±400 N shear load was imposed. Markers were drawn on the facet capsule surface and their coordinates were tracked during pre- and post-impact range-of-motion tests. Strain was defined as the change in point configuration relative to the determined neutral joint posture. There were no significant differences (p > 0.05) observed in all calculated FJC strain components in rotation and translation before and after the simulated impact. Our results suggest that LBP development resulting from the initiation of strain-induced mechanoreceptors and nociceptors with the facet joint capsule is unlikely following a severe rear impact collision within the boundaries of physiological joint motion.
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Introduction: Low back pain is one of the most common disorders in modern society. Disturbed properioception can be a possible cause of low back pain and can cause recurrence of low back pain. Previous studies have shown that low back pain reduces proprioception due to instability in the low back. Since the degenerative process of disc herniation is one of the important factors in exacerbating the known low back pain process, it is not clear whether the degeneration of the lumbar disc exacerbates the deficits of proprioception or the proprioception reduction is resulted from the low back pain itself. The aim of this study was to dertimine whether disk degeneration is the cause of proprioception reduction or not? Materials and Methods: This observation study was performed on 70 patients with low back pain (35 people with chronic non-specific low back pain and 35 people with discopathic low back pain). Remarkably, the repositioning error of the forward bending angles at 30% and 60% of the total lumbar flexion angle and the neutral angle was measured by a digital electrogoniometer. Results: Based on the measurements of absolute error in 30% of the total range of motion (1.97±2.02 in patients with chronic nonspecific low back pain versus 1.92±1.04 in discopathic individuals, P=0.892) and 60% of the total range of motion (2.30±1.96 vs. 2.01±1.09, P=0.450) and neutral angle (1.74±1.36 vs. 1.44±1.41, P=0.370), there was no significant difference between these two groups. Conclusion: Patients with low back pain may have altered proprioception, but due to the lack of significant differences in proprioception between chronic nonspecific low back pain patients and discopathic patients, other factors appear to be involved in the exacerbation of low back pain disorder.
Article
Various interpretations and parameters have been proposed to assess spinal stability such as antagonist muscle coactivity, trunk stiffness and spinal buckling load; however, the correlation between these parameters remains unknown. We evaluated spinal stability during different tasks while changing the external moment and load height and investigated likely relationships between different EMG- and model-based parameters (e.g., EMG coactivity ratio, trunk stiffness, force coactivity ratio) and stability margins. EMG and kinematics of 40 young healthy subjects were recorded during various quasi-static tasks. Muscle forces, trunk stiffness and stability margins were calculated by a nonlinear subject-specific EMG-assisted-optimization musculoskeletal model of the trunk. The load elevation and external moment increased muscle activities and trunk stiffness while all stability margins (i.e., buckling loads) decreased. The force coactivity ratio was strongly correlated with the hand-load stability margin (i.e., additional weight in hands to initiate instability; R² = 0.54) demonstrating the stabilizing role of abdominal muscles. The total trunk stiffness (Pearson’s r = 0.96) and the sum of EMGs of back muscles (Pearson’s r = 0.65) contributed the most to the T1 stability margin (i.e., additional required load at T1 for instability/buckling). Force coactivity ratio and trunk stiffness can be used as alternative spinal stability metrics.
Article
Introduction Patients with chronic non-specific low back pain (CNSLBP) were found with impaired postural control in previous studies. Since the trunk muscle take important efforts on core stability, the study aimed to examine the relationships of postural control during stance tasks and the contractility of trunk muscle in young adults with CNSLBP and without. Methods Healthy individuals (n=25) and individuals with CNSLBP (n=30) were included. The thickness of the bilateral transversus abdominis (TrA) and lumbar multifidus (MF) was measured during rest and maximal voluntary contraction, and the change percentages (TrA%, MF%) were calculated. Regarding postural control, COP path length and sway area during the stance tasks were measured thrice in each group. Results The bilateral TrA% of the CNSLBP group was less than that of the HC group (p<0.05). The bilateral TrA% of the CNSLBP group was less than that of the HC group (p<0.05). The bilateral MF% showed no significantly different(p>0.05) between the two groups. Compared with healthy controls, CNSLBP patients resulted larger path length and sway area of COP during most of static stance tasks. During the EO task in the CNSLBP group, TrA% was found correlate to COP path length (p<0.05); the right MF% was correlated with COP sway area (p<0.05). No significant correlations appeared in the healthy controls (p>0.05). Conclusions Compared with healthy individuals, impaired postural control during static stance with eyes open in patients with CNSLBP was likely to be related to the poor contraction ability of bilateral transversus abdominis and correlated to the normal contraction ability of right lumbar multifidus.
Article
Background: The function of trunk muscles in chronic nonspecific low back pain (CNLBP) is controversially discussed, and trunk muscle function in sedentary occupation workers is poorly understood. Objective: To investigate whether muscle function differs between sedentary occupation workers with and without CNLBP and to determine the association between functional limitations and muscle function. Methods: This study included 32 sedentary occupation workers (16 workers with CNLBP and 16 age- and sex-matched workers without CNLBP). Group differences in isokinetic trunk flexion-extension strength, muscle cocontraction, endurance time (Biering-Sorensen test) and electromyographic muscle fatigue were assessed. The association of these parameters and Oswestry Disability Index (ODI) score were examined in the CNLBP group. Results: Participants with CNLBP had lower trunk extensor (-20%) and flexor (-18%) strength and less cocontraction (-22%) than participants without CNLBP, but due to large variability in both groups these differences were not statistically significant. Trunk muscle endurance and fatigue were comparable between groups. Variance in endurance time explained 28% of variance in the ODI-score in the CNLBP group (R2= 0.277). Conclusions: In patients with CNLBP, greater functional disability was associated with lower endurance. Further evidence is necessary to elucidate whether specifically training endurance performance may be beneficial for sedentary occupation workers.
Article
Study design: Numerical in-silico human spine stability finite element analysis. Objective: The purpose of this study was to investigate the contribution of major torso tissues toward static spine stability, mainly the thoracolumbar fascia (TLF), abdominal wall with its intra-abdominal pressure (IAP), and spinal muscles inclusive of their intramuscular pressure. Summary of background data: Given the numerous redundancies involved in the spine, current methodologies for assessing static spinal stability are limited to specific tissues and could lead to inconclusive results. A three-dimensional finite element model of the spine, with structured analysis of major torso tissues, allows for objective investigation of static spine stability. Methods: A novel previously fully validated spine model was employed. Major torso tissues, mainly the muscles, TLF, and IAP were individually, and in combinations, activated under a 350N external spine perturbation. The stability contribution exerted by these tissues, or their ability to restore the spine to the unperturbed position, was assessed in different case-scenarios. Results: Individual activations recorded significantly different stability contributions, with the highest being the TLF at 71%. Combined or synergistic activations showed an increase of up to 93% stability contribution when all tissues were simultaneously activated with a corresponding decrease in the tensile load exerted by the tissues themselves. Conclusion: This investigation demonstrated torso tissues exhibiting different roles toward static spine stability. The TLF appeared able to dissipate and absorb excessive loads, the muscles acted as antagonistic to external perturbations, and the IAP played a role limiting movement. Furthermore, the different combinations explored suggested an optimized engagement and coordination between different tissues to achieve a specific task, while minimizing individual work.Level of Evidence: N/A.
Article
Background: New motor adaptation to pain theory suggests that patients with low back pain (LBP) use the lumbopelvic stiffening strategy by redistribution of within and between muscle activities to protect painful structure. This could result in an altered postural control of the lumbopelvic region during active prone hip rotation (PHR). Objective: To investigate coordination and timing of lumbopelvic and hip movements, and smoothness of the lumbopelvic control during PHR between participants with and without LBP. Methods: Eight participants with LBP and eight participants without LBP were recruited. The electromagnetic tracking system was used to record kinematic data during PHR. Cross-correlation between hip rotation and lumbopelvic movement in the transverse plane was calculated. Correlation at zero time-lag, time-lag, correlation at time-lag, and maximal lumbopelvic motion were derived. Frequency of movement disruption was identified. An independent t-test was used in conjunction with the effect size and 95% minimal detectable difference (MDD95) to determine the difference in kinematic parameters. Results: Participants with LBP demonstrated a significant delay (exceeding MDD95) in lumbopelvic motion while nonsignificant frequency of disrupted motion on the painful side PHR demonstrated a trend with a large effect size that exceeded MDD95. There were trends with moderate to large effect sizes and differences exceeding MDD95 in delay of lumbopelvic motion with greater movement disruption on the nonpainful side in participants with LBP. Conclusion: Participants with LBP used a lumbopelvic stiffening strategy for postural control to protect painful structures; however, the stiffening might complicate efforts to smoothly control lumbopelvic movement.
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The neutral zone is a region of intervertebral motion around the neutral posture where little resistance is offered by the passive spinal column. Several studies--in vitro cadaveric, in vivo animal, and mathematical simulations--have shown that the neutral zone is a parameter that correlates well with other parameters indicative of instability of the spinal system. It has been found to increase with injury, and possibly with degeneration, to decrease with muscle force increase across the spanned level, and also to decrease with instrumented spinal fixation. In most of these studies, the change in the neutral zone was found to be more sensitive than the change in the corresponding range of motion. The neutral zone appears to be a clinically important measure of spinal stability function. It may increase with injury to the spinal column or with weakness of the muscles, which in turn may result in spinal instability or a low-back problem. It may decrease, and may be brought within the physiological limits, by osteophyte formation, surgical fixation/fusion, and muscle strengthening. The spinal stabilizing system adjusts so that the neutral zone remains within certain physiological thresholds to avoid clinical instability.
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Presented here is the conceptual basis for the assertion that the spinal stabilizing system consists of three subsystems. The vertebrae, discs, and ligaments constitute the passive subsystem. All muscles and tendons surrounding the spinal column that can apply forces to the spinal column constitute the active subsystem. The nerves and central nervous system comprise the neural subsystem, which determines the requirements for spinal stability by monitoring the various transducer signals, and directs the active subsystem to provide the needed stability. A dysfunction of a component of any one of the subsystems may lead to one or more of the following three possibilities: (a) an immediate response from other subsystems to successfully compensate, (b) a long-term adaptation response of one or more subsystems, and (c) an injury to one or more components of any subsystem. It is conceptualized that the first response results in normal function, the second results in normal function but with an altered spinal stabilizing system, and the third leads to overall system dysfunction, producing, for example, low back pain. In situations where additional loads or complex postures are anticipated, the neural control unit may alter the muscle recruitment strategy, with the temporary goal of enhancing the spine stability beyond the normal requirements.
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Articles describing motor function in five chronic musculoskeletal pain conditions (temporomandibular disorders, muscle tension headache, fibromyalgia, chronic lower back pain, and postexercise muscle soreness) were reviewed. It was concluded that the data do not support the commonly held view that the pain of these conditions is maintained by some form of tonic muscular hyperactivity. Instead, it seems clear that in these conditions the activity of agonist muscles is often reduced by pain, even when this does not arise from the muscle itself. On the other hand, pain causes small increases in the level of activity of the antagonist. As a consequence of these changes, force production and the range and velocity of movement of the affected body part are often reduced. To explain how such changes in the behaviour come about, we propose a neurophysiological model based on the phasic modulation of excitatory and inhibitory interneurons supplied by high-threshold sensory afferents. We suggest that the "dysfunction" that is characteristic of several types of chronic musculoskeletal pain is a normal protective adaptation and is not a cause of pain.
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Although often suggested as a control measure to alleviate musculoskeletal stresses, the use of mechanical assistance devices (i.e. manipulators) in load transfers has not been extensively studied. Without data describing the biomechanical effects of such devices, justification for decisions regarding implementation of such tools is difficult. An experimental study of two types of mechanical manipulators (articulated arm and overhead hoist) was conducted to determine whether biomechanical stresses, and hence injury risk, would be alleviated. Short distance transfers of loads with moderate mass were performed both manually and with manipulator assistance under a variety of task conditions. Using analysis and output from new dynamic torso models, strength demands at the shoulders and low back, lumbar spine forces, and lumbar muscle antagonism were determined. Strength requirements decreased significantly at both the shoulders and low back when using either manipulator in comparison with similar transfers performed manually. Peak spine compression and anterior-posterior (a-p) shear forces were reduced by about 40% on average, and these reductions were shown to be primarily caused by decreases in hand forces and resultant spinal moments. Two metrics of muscular antagonism were defined, and analysis showed that torso muscle antagonism was largest overall when using the hoist. The results overall suggest that hoist-assisted transfers, although better in reducing spine compression forces, may impose relatively higher demands on coordination and/or stability at extreme heights or with torso twisting motions. The relatively higher strength requirements and spine compression associated with the articulated arm may be a result of the high inertia of the system. Potential benefits of practice and training are discussed, and conclusions regarding implementation of mechanical manipulators are given.
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Estimates of the amount of force exerted by a muscle using electromyography (EMG) rely partially upon the accuracy of the reference point used in the normalization technique. Accurate representations of muscle activities are essential for use in EMG-driven spinal loading models. The expected maximum contraction (EMC) normalization method was evaluated to explore whether it could be used to assess individuals who are not capable of performing a maximum exertion such as a person with a low back injury. Hence, this study evaluated the utility of an EMG normalization method (Marras and Davis, A non-MVC EMG normalization technique, Part 1, method development. Journal of Electromyography and Kinesiology 2000) that draws upon sub-maximal exertions to determine the reference points needed for normalization of the muscle activities. The EMC normalization technique was compared to traditional MVC-based EMG normalization by evaluating the spinal loads for 20 subjects (10 males and 10 females) performing dynamic lifts. The spinal loads (estimated via an EMG-assisted model) for the two normalization techniques were very similar with differences being <8%. The model performance variables indicated that both normalization techniques performed well (r(2)>0.9 and average error below 6%) with only the muscle gain being affected by normalization method as a result in different reference points. Based on these results, the proposed normalization technique was considered to be a viable method for EMG normalization and for use in EMG-assisted models. This technique should permit the quantitative evaluation of muscle activity for subjects unable to produce maximum exertions.
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Normalization of muscle activity has been commonly used to determine the amount of force exerted by a muscle. The most widely used reference point for normalization is the maximum voluntary contraction (MVC). However, MVCs are often subjective, and potentially limited by sensation of pain in injured individuals. The objective of the current study was to develop a normalization technique that predicts an electromyographic (EMG) reference point from sub-maximal exertions. Regression equations predicting maximum exerted trunk moments were developed from anthropometric measurements of 120 subjects. In addition, 20 subjects performed sub-maximal and maximal exertions to determine the necessary characteristic exertions needed for normalization purposes. For most of the trunk muscles, a highly linear relationship was found between EMG muscle activity and trunk moment exerted. This analysis determined that an EMG-moment reference point can be obtained via a set of sub-maximal exertions in combination with a predicted maximal exertion (expected maximum contraction or EMC) based upon anthropometric measurements. This normalization technique overcomes the limitations of the subjective nature for the MVC method providing a viable assessment method of individuals with a low back injury or those unwilling to exert an MVC as well as could be extended to other joints/muscles.
Article
The intersegmental and multisegmental musculature of the lumbar spine was studied in a biomechanical model to compare their lateral stabilizing potential. By approximating the active and passive behavior of the stretch reflex as a variable stiffness spring whose stiffness was proportional to activation, the critical muscle stiffness required for mechanical stability was calculated. The model demonstrated that the intersegmental muscles were the least efficient at laterally stabilizing the spine. At any given load, multisegmental muscles were more efficient, and their efficiency increased with the number of segments spanned. The most efficient muscles were those that originated from the pelvis, spanning the maximum number of segments. The muscular model was unstable, regardless of the muscular stiffness, when any vertebral segment was devoid of muscle. Moreover, when the load on the spine is increased, buckling can be prevented most efficiently with the pelvic muscles and least efficiently with the intersegmental muscles.
Article
Estimates of peak spinal compression in manual materials handling were compared between a state-of-the-art laboratory technique and a method applicable at the worksite. Nine experienced masons performed seven simulated tasks in a mock-up in the laboratory and nine matched masons were studied during actual performance of the same tasks at the worksite. From kinematic and kinetic data obtained in the laboratory, compression forces on the L5S1 joint were calculated. In addition, compression forces were estimated from the horizontal and vertical position of the blocks handled relative to the subject measured at the worksite. Comparison of group-averaged values showed that the worksite method underestimated peak compression by about 20%. Rank ordering of tasks for back load was, however, consistent between methods, supporting validity of the worksite method to compare different tasks or to determine the effects of ergonomic interventions with regard to mechanical back load. Statement of Relevance: This study validated a method that can be used by ergonomists to determine the effects of (characteristics of) manual materials handling tasks on back load at the worksite.
Article
The existence of a pain-spasm-pain cycle in musculoskeletal disorders has been debated for over 40 years. This paper reviews critically the evidence for such a cycle in patients with back pain. Clinical studies indicate that a substantial proportion of patients with back pain have muscle spasm. Patients with acute back pain have increased muscular activity on electromyography (EMG). EMG studies of patients with chronic back pain show, on the whole, an increase in activity in static postures, and a reduction of muscle activity during movement. Experimental evidence shows that pain may cause muscle spasm and that muscular activity can be painful. Further evidence for the existence of a pain-spasm-pain cycle comes from studies which show that analgesics can reduce muscle spasm, and that a variety of muscle relaxant techniques can reduce pain. There are substantial methodological problems in many of the studies cited, but the evidence reviewed provides general support for the existence of a pain-spasm-pain cycle. However further work is required to determine the nature of spasm and to evaluate methods for its detection, particularly in acute back pain syndromes. The value of therapeutic intervention may then be assessed.
Article
Scaling of postural ankle-muscle responses was compared for transient (forward and backward acceleration pulses) and continuous (pseudorandom acceleration) platform-translation perturbations. The two types of perturbation were designed to be unpredictable, to have similar frequency content, and to represent similar levels of challenge to stability. A repeated measures experimental design was used to test 12 healthy young (20–45 years) males. Each type of perturbation was administered at three acceleration levels, in random order, and the tests were repeated under eyes-open and blindfolded conditions, while controlling for order of testing. Individual ankle-muscle responses were quantified and, in addition, used to estimate a net response measure (proportional to net ankle torque) and measures of antagonist activation and relative co-contraction level. The results failed to show strong evidence of differences between transient and continuous postural control with regard to the influence of vision, as both types of response were largely unaffected by vision deprivation; however, the results did demonstrate some substantial perturbation-dependent differences in the scaling of the responses to perturbations of differing magnitude. The most pronounced differences, seen in tibialis anterior, appeared to be related to a tendency to lean slightly further forward during continuous perturbations. Substantial co-contraction of antagonistic muscles was frequently observed, for both types of perturbation, and antagonist activation tended to increase at larger perturbation magnitudes. The observed differences in the scaling of the transient and continuous responses raise some concerns about the generalizability of posture control models derived from continuous-perturbation tests.
Article
When a patient presents himself with the common complaint of pain in the shoulder region and arm, with or without limitation of motion and unrelated to severe trauma, the physician usually thinks of the joints, bursae, tendons or nerves rather than of the shoulder girdle muscles as the primary source of pain. Thus the customary diagnosis in this type of patient is either arthritis, subacromial bursitis, brachial neuritis or radiculitis. The well known chronicity of these symptoms and the variety of therapeutic procedures employed suggest either that the customary methods of treatment are unsatisfactory or that the underlying cause is often overlooked. It is our purpose in this report to discuss the diagnosis of a type of pain in the shoulder and arm which has its origin in the muscles of the back or shoulder girdle and to present the results of an effective method of therapy, namely intramuscular infiltration
Article
Chronic low back pain (CLBP) is a major clinical problem with a substantial socio-economical impact. Today, diagnosis and therapy are insufficient, and knowledge concerning interaction between musculoskeletal pain and motor performance is lacking. Most studies in this field have been performed under static conditions which may not represent CLBP patients' daily-life routines. A standardized way to study the sensory-motor interaction under controlled motor performance is to induce experimental muscle pain by i.m. injection of hypertonic saline. The aim of the present controlled study was to analyze and compare electromyographic (EMG) activity of and coordination between lumbar muscles (8 paraspinal recordings) during gait in 10 patients with CLBP and in 10 volunteers exposed to experimental back muscle pain induced by bolus injection of 5% hypertonic saline. When the results are compared to sex- and age-matched controls, the CLBP patients showed significantly increased EMG activity in the swing phase; a phase where the lumbar muscles are normally silent. These changes correlated significantly to the intensity of the back pain. Similar EMG patterns were found in the experimental study together with a reduced peak EMG activity in the period during double stance where the back muscles are normally active. Generally, these changes were localized ipsilaterally to the site of pain induction. The clinical and experimental findings indicate that musculoskeletal pain modulates motor performance during gait probably via reflex pathways. Initially, these EMG changes may be interpreted as a functional adaptation to muscle pain, but the consequences of chronic altered muscle performance are not known. New possibilities to monitor and investigate altered motor performance may help to develop more rational therapies for CLBP patients.
Article
Surface electromyographic (EMG) activity recordings of bilateral paraspinal muscle tension were measured twice on 20 non-pain controls and on 46 low back pain subjects (21 individuals with intervertebral disk disorders and 25 subjects with unspecified musculoskeletal backache) during 6 positions: standing, bending from the waist, rising, sitting with back unsupported, sitting with back supported, and prone. Back pain subjects were measured during both low pain and high pain states. Results revealed a non-significant trend for all subjects, regardless of diagnosis, to have higher paraspinal muscle tension levels on the second (or high pain) assessment. A significant diagnosis by position interaction was observed which was similar to the interaction in our previous study which employed only a single measurement session. Analysis of simple main effects revealed this to be due to control subjects during the standing position having lower EMG levels than the back pain groups, and intervertebral disk disorder subjects having higher EMG levels than the other groups during the supported sitting position. As in our previous study, diagnosis was found to be a clinically significant factor, in that controls had much fewer clinically abnormal readings than back pain patients. The lack of a significant effect for pain state is congruent with findings in the headache literature. The importance of clearly defined diagnostic categories in low back pain research and the utility of measuring subjects in various positions is discussed, as are possible explanations for lack of significant pain state findings.
Article
Unlabelled: The functioning of low back muscles of back pain patients during flexion and reextension has not been properly investigated. In this study, we analyzed rectified, averaged electric activity (RMS EMG) and corresponding raw intramuscular (IM) EMG from lumbar paraspinal muscles to quantify the activity level during simple bending cycles in 87 back pain patients compared to 25 able-bodied controls. The results: All functional phases seen in raw IM EMG were also shown in surface RMS EMG. Surface RMS EMG pattern seems to yield more information from activity level than IM EMG pattern. The RMS EMG patterns of back pain patients differed from those of controls as follows: (1) There was clearly noticeable activity during standing in back pain patients. (2) There was only a partial decrease of EMG activity after flexion in back pain patients with current pain. (3) The ratio of mean reached at maximal activity level during extension and flexion was less in patients (1.8, SD = 0.5, p less than .001) than able-bodied controls (3.2, SD = 0.8). (4) Segmental differences were observed in IM EMG activities in patients having hypermobility in bending x-ray. (5) Large peak potentials occurred during movements in patients having segmental hypermobility. THE RESULTS indicate that averaged surface recording is a valuable tool in the investigation of dynamic spine functions in back pain patients.
Article
The intersegmental and multisegmental musculature of the lumbar spine was studied in a biomechanical model to compare their lateral stabilizing potential. By approximating the active and passive behavior of the stretch reflex as a variable stiffness spring whose stiffness was proportional to activation, the critical muscle stiffness required for mechanical stability was calculated. The model demonstrated that the intersegmental muscles were the least efficient at laterally stabilizing the spine. At any given load, multisegmental muscles were more efficient, and their efficiency increased with the number of segments spanned. The most efficient muscles were those that originated from the pelvis, spanning the maximum number of segments. The muscular model was unstable, regardless of the muscular stiffness, when any vertebral segment was devoid of muscle. Moreover, when the load on the spine is increased, buckling can be prevented most efficiently with the pelvic muscles and least efficiently with the intersegmental muscles.
Article
The attachments and orientation of every fascicle of the lumbar erector spinae were determined in five cadavers and recorded radiographically. Little variation was found in the sites of muscle attachment, which enabled the construction of maps whereby these sites could be plotted on clinical radiographs or models of the lumbar spine. When all fascicles were plotted on 21 clinical radiographs using the maps previously developed, no significant difference in the orientation of fascicles was found compared with that observed in cadavers. This result vindicates the technique used to plot the location of individual fascicles of the lumbar back muscles.
Article
Surface EMG recordings of bilateral paraspinal muscle tension were measured on 207 subjects (29 non-back pain controls, 20 individuals with spondyloarthritis, 52 with intervertebral disk disorders, 66 with unspecified musculoskeletal backache, 17 with some combination of the above 3 groups and 23 subjects with other types of back pain, including unknown, scoliosis and psychogenic) in 6 positions: standing, bending from the waist, rising, sitting with back unsupported, sitting with back supported and prone. Results of both individual and group analyses revealed a significant main effect of diagnosis. Post hoc analyses (Duncan's) revealed controls to have significantly lower overall EMG levels than the intervertebral disk disorders and unspecified musculoskeletal backache groups. A significant diagnosis by position interaction was observed. Analysis of simple main effects revealed this to be due primarily to control subjects during the standing position having lower EMG levels than all other groups, and intervertebral disk disorder subjects having higher EMG levels than all other groups during the supported sitting position. The importance of clearly defined diagnostic categories in low back pain research and the utility of measuring subjects in various positions are discussed.
Article
The myoelectric activity of selected trunk muscles at the L3 level was studied during the development of a controlled isometric axial torque. Muscle activity was recorded with surface electrodes bilaterally over the erector spinae muscles, the rectus abdominus, the obliques externus, and the obliques internus. Subjects applied graded isometric axial torque efforts with the addition of a Valsalva. The largest myoelectric activities were recorded over the obliques externus and internus. The side of the muscle developing the torque did show the greatest myoelectric activity, but considerable antagonistic activity was also present. Neither the rectus abdominus nor the internal oblique muscles showed any difference from side to side. The calculated forces in the rectus abdominus and the erectores spinae were high, suggesting that a considerable amount of the muscle contraction was used to control the posture. A Valsalva did not decrease myoelectric activity, but did increase the torque developed.
Article
It has been suggested that the muscles of the anterolateral abdominal wall increase the stability of the lumbar region of the vertebral column by tensing the thoracolumbar fascia and by raising intra-abdominal pressure. In this report these new mechanisms are reviewed and their contribution to vertebral stability assessed. The thoracolumbar fascia consists of two principal layers of dense fibrous tissue that attach the abdominal muscles to the vertebral column. Each of these layers was dissected in fresh and fixed material and samples chosen for light and scanning electron microscopy to study the arrangement of the component fibers. Computed axial tomography in volunteers showed the changes in spatial organization that occur during flexion of the back and during the Valsalva maneuver. The fascia was then tensed experimentally in isolated unfixed motion segments. The results suggested that the stabilizing action of the thoracolumbar fascia is less than had been thought previously but was consistent with calculations based on the more accurate structural and mechanical information that had been derived from the current study. Abdominal muscle contraction was simulated in whole cadavers in both the flexed and lateral bending positions to compare the stabilizing effect of the thoracolumbar fascia and intra-abdominal pressure mechanisms. These definitive experiments showed that the resistance to bending in the sagittal plane offered by the abdominal muscles acting through fascial tension was of a similar magnitude to that offered by a raised intra-abdominal pressure, both being relatively small in the fully flexed position. The stabilizing influence of the middle layer of the thoracolumbar fascia in lateral bending was clearly demonstrated and warrants further study in vivo.
Article
A study was undertaken to examine relations among some objective and subjective measures of low-back-related disability in a group of 41 low-back pain patients and in seven pain-free control subjects. Subjective measures of disability were obtained by Oswestry patient questionnaires. Oswestry disability score related significantly (P less than 0.001) to presence or absence of relaxation in back muscles during flexion. Mean trunk strength ratios were inversely related to disability score (P less than .05), and trunk mobility was meaningfully reduced (P less than .01). Despite loss of motion, a large enough excursion was observed to predict presence of back muscle relaxation. These findings imply that myoelectric signal levels, trunk strength ratios, and ranges of trunk motion may be used as objective indicators of low-back pain disability.
Article
Bilateral paraspinal electromyogram (EMG) at levels L1-L2 and L4-L5, and abdominal EMG of a group of 20 low-back pain patients were compared to those of a group of 20 pain-free controls during flexion, extension, lateral bending to right and left, and rotation to right and left. The results showed no significant left-right differences in paraspinal EMG levels between low-back pain patients and pain-free controls during any of the movements. However, patterns of paraspinal and abdominal EMG were found to be different for low-back pain patients compared to pain-free controls during flexion only.
Article
According to myogenic models that relate abnormal EMG patterns to the experience of pain, lumbar paravertebral muscle activity has been considered to play an important role in chronic low back pain. In the present study, 40 chronic low back pain patients and 40 matched non-patient controls were compared on lumbar paravertebral EMG during mechanically stabilized static and dynamic postures. Differences between groups in lumbar curvature and spinal range of motion were determined using a dual goniometer technique. Although the two groups did not differ on absolute levels of EMG during quiet standing, significant differences were found for EMG patterns during dynamic postures. In addition, most patients did not show the flexion-relaxation response or the expected pattern of EMG responses during trunk rotation, most likely because of restricted range of motion and/or compensatory posturing. These findings provide support for the biomechanical model of chronic pain and indicate the need for further research pertaining to pain behavior and movement-related lumbar muscle activity.
Article
This is the second part of an extended review of the etiology and treatment of chronic back pain (CBP). The first paper dealt with somatic factors and interventions, this paper will examine psychological theories on the etiology of CBP and psychological treatments for CBP. Finally common problems of both the somatic and the psychological approaches will be discussed and suggestions for treatment and research will be made.
Article
This is the first part of an extended review of the etiology and treatment of chronic back pain (CBP). This paper will address the pathophysiology of CBP, the somatic conceptualizations that have been developed, and the treatment modalities that have been employed to alleviate the symptoms. The adequacy of the different models and treatments will be critically examined. The second paper in this set will examine psychological models and interventions. Common problems to both somatic and psychological approaches will be discussed at the close of the second paper.
Article
A three‐dimensional muscle model with complex geometry is described and tested against experimental data. Using this model, several muscles were constructed. These muscles have equal optimum length but differ in architecture. The force exerted by the constructed muscles, in relation to their actual length and velocity of shortening, is discussed. Generally speaking, the constructed muscles with considerable pennation have great fiber angles, a great physiological cross section, a narrow active and steep passive length‐force relation, and a low maximal velocity of shortening. The maximal power (force times velocity) delivered by the constructed muscles is shown to be almost independent of the architecture of the muscles. The steepness of the passive length‐force relation is determined mainly by the shortest fibers within the group of constructed muscles, wheras maximal velocity of shortening and the width of the active length‐force relation are determined mainly by the longest fibers. The validity of the three‐dimensional muscle model with respect to some morphological and functional characteristics is tested. Length‐force relations of constructed muscles are compared with the actual length‐force relations of mm. gastrocnemii mediales and mm. semimembranosi of male Wistar rats. Moreover, actual fiber angle, fiber length, and muscle thickness of three mm. gastrocnemii mediales are compared with values found for constructed muscles. It is concluded that the three‐dimensional muscle model closely approximates the actual muscle form and function.
Article
The purpose of this study was to determine whether the same estimates of individual muscle and L4/L5 lumbar joint compressive forces result from an optimization (OPT) compared to an electromyography (EMG) assisted approach for solving the inderminate moment equilibrium equations in the same anatomical model. Four male subjects performed near maximum, isometric, ramp efforts in trunk flexion, extension and lateral bending in a testing apparatus. The EMG approach was sensitive to subject and trial differences in the magnitudes of individual muscle forces needed to produce the same reaction moment. In contrast, the OPT method converged on a similar estimate of muscle forces for all subjects and trials producing the same moment. The OPT method predicted lower L4/L5 joint compression values, on average, by 32, 43 and 23% in trunk extension, flexion and lateral bending, respectively, because, unlike the EMG method, it could not predict co-contraction of anatomically antagonistic muscles. We incorporated the OPT method's advantage of forcing an equilibrium in the reaction moments into the EMG method in a new approach we have called 'EMG assisted optimization' (EMGAO). Muscle force estimates from the EMG and EMGAO methods differed from those from the OPT method, on average, by 123% (RMS) for flexion and extension and by 218% for lateral bends. Data from the two approaches result in different conclusions about spine mechanics. We have more confidence in the EMG assisted methods because they respond to variation in muscle synergy and co-contraction patterns commonly observed in different trials and subjects for the same reaction moments.
Article
The transmission of load through the lumbar spine was analyzed in a model of the five lumbar vertebrae, the sacrum/pelvis and the thorax, and 66 symmetric pairs of multijoint muscles. The model was used to test the hypotheses that (1) the need to maintain equilibrium simultaneously at all vertebral levels precludes simultaneous maximum activation of synergistic muscles and (2) that the maximum loads which could be carried by the spine and the degree of muscle activation increases with increasing motion segment stiffness. Maximum moments applied to T12 were calculated for moments in three principal directions, subject to equilibrium at all six joints and to constraints on the maximum muscle stress and intervertebral displacements. A model with realistic motion segment stiffness predicted maximum efforts between 1.4 and 3.3 times greater than a model with 'ball-and-socket' joints, and in better agreement with published results from maximum effort experiments. The differences in maximal effort were greater than the moments transmitted through the joints. While muscle activation levels were greater, many synergistic muscles were still submaximally activated. Antagonistic muscles were recruited to maintain multijoint equilibrium. We concluded that (1) muscle activations permitted in single anatomic level analyses are generally not compatible with equilibrium at other levels; (2) the effect of moment transmission in the joints gives a more realistic representation of the lumbar spine.
Article
This work investigated the passive bending properties of the intact human torso about its three principal axes of flexion: extension, lateral bending, and axial rotation. Additionally, the effects of wearing an abdominal belt and holding the breath (full inhalation) on trunk stiffness was investigated. The torsos of 22 males and 15 females were subjected to bending moments while "floating" in a frictionless jig with isolated torso bending measured with a magnetic device. Belts and breath holding appear to stiffen the torso about the lateral bending and axial rotation axes but not in flexion or extension. Torsos are stiffer in lateral bending and capable of storing greater elastic energy. Regression equations were formulated to define stiffness and energy stored for input to biomechanical models that examine low back function and for bioengineers designing hardware for stabilization and bracing or investigation of traumatic events such as automobile collision.