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PubMed2005

Relationships of EMG to effort in the trunk under isometric conditions: force-increasing and decreasing effects and temporal delays.

BACKGROUND: Electromyograms are used in increasingly sophisticated biomechanical analyses to estimate forces within the trunk to prevent and evaluate painful spinal conditions. However, even under nominally isometric conditions the relationship between EMG and effort is complex. This study quantified influences of pulling direction, increasing versus decreasing effort and electromechanical delay on the EMG/effort relationships for principal lower trunk muscle groups in isometric pulling tasks, to determine whether the observed differences between increasing versus decreasing effort relationships were consistent with electromechanical delay or activation differences. METHODS: Twenty-three healthy subjects (15 male, 8 female; mean age 32 years; mean bodymass 74.5 kg) each stood in an apparatus to stabilize the pelvis and performed ramped isometric efforts with a harness around the thorax connected to each of a series of five anchor points on the wall, for angles of pull at each 45 degrees increment from 0 degrees to 180 degrees to the anterior direction. A load cell recorded the generated force for a 5 s timed increase up to a voluntary maximum, a 1s 'dwell', and a 5 s relaxation back to zero effort. EMG signals were recorded via electrodes (surface, except indwelling for multifidus) from right and left rectus abdominis, internal and external obliques, longissimus, iliocostalis and L2 and L4 level multifidus. EMG signals were rectified with a 250 ms root-mean-square moving average filter. Effort-increasing and effort-decreasing sections of recordings were analyzed separately. FINDINGS: The EMG/effort relationship had a statistically significantly greater gradient as the effort was increasing than when decreasing for 28 of 70 muscle-angle permutations. This difference in gradient was found to explain a significant part of the apparent lag between effort generated and EMG signal that averaged between 261 and 658 ms before and between 31 and 196 ms for different muscles after the slope difference was taken into account. INTERPRETATION: The findings were consistent with the notion that the motor unit recruitment differs in increasing versus decreasing isometric efforts, probably because of a small stretching of the muscle as its tension increases. The residual temporal delay was thought to represent electromechanical delay.

Adaptation, Physiological↗
PubMed2005

Changes in three dimensional lumbo-pelvic kinematics and trunk muscle activity with speed and mode of locomotion.

BACKGROUND: Control of the trunk is critical for locomotor efficiency. However, investigations of trunk muscle activity and three-dimensional lumbo-pelvic kinematics during walking and running remain scarce. METHODS: Gait parameters and three-dimensional lumbo-pelvic kinematics were recorded in seven subjects. Electromyography recordings of abdominal and paraspinal muscles were made using fine-wire and surface electrodes as subjects walked on a treadmill at 1 and 2 ms(-1) and ran at 2, 3, 4 and 5 ms(-1). FINDINGS: Kinematic data indicate that the amplitude but not timing of lumbo-pelvic motion changes with locomotor speed. Conversely, a change in locomotor mode is associated with temporal but not spatial adaptation in neuromotor strategy. That is, peak transverse plane lumbo-pelvic rotation occurs at foot strike during walking but prior to foot strike during running. Despite this temporal change, there is a strong correlation between the amplitude of transverse plane lumbo-pelvic rotation and stride length during walking and running. In addition, lumbo-pelvic motion was asymmetrical during all locomotor tasks. Trunk muscle electromyography occurred biphasically in association with foot strike. Transversus abdominis was tonically active with biphasic modulation. Consistent with the kinematic data, electromyography activity of the abdominal muscles and the superficial fibres of multifidus increased with locomotor speed, and timing of peak activity of superficial multifidus and obliquus externus abdominis was modified in association with the temporal adaptation in lumbo-pelvic motion with changes in locomotor mode. INTERPRETATION: These data provide evidence of the association between lumbo-pelvic motion and trunk muscle activity during locomotion at different speeds and modes.

Adaptation, Physiological↗
PubMed2006

The effect of increasing resistance on trunk muscle activity during extension and flexion exercises on training devices.

Although progressive resistance training of trunk muscles on devices is very common, today, the effects of increasing resistance on trunk muscle activity during dynamic extension and flexion movements on training devices have not been reported yet. Thirty healthy subjects participated in maximal isometric and submaximal dynamic (at 30%, 50% and 70% of maximum mean torque (MMT)) extension and flexion exercises on Tergumed lumbar training devices. The normalized (as a percentage of maximal voluntary isometric contractions (MVIC)) electromyographic activity of 16 abdominal and back muscles was investigated. The results of the present study indicated that in general, with increasing resistance from 30% MMT to 50% MMT and 70% MMT, the activity of all back muscles during the extension exercises and the activity of all abdominal muscles during the flexion exercises increased significantly. To train strength (>60% of MVIC), low intensities (30% and 50% MMT) appeared sufficient to affect the back muscles, but for the abdominals higher resistance (70% MMT) was required. In contrast to the other back muscles, the lumbar multifidus demonstrated high activity levels during both the extension and the flexion exercises. As the lumbar multifidus is demonstrated to be an important muscle in segmental stabilization of the lumbar spine, this finding may help in understanding the efficacy of rehabilitation programs using specific training devices.

Abdominal Muscles↗
PubMed2004

Anatomical relationships between selected segmental muscles of the lumbar spine in the context of multi-planar segmental motion: a preliminary investigation.

In the last decade, concepts regarding spinal stability have been redefined. Whereas traditional stability models considered only the integrity of the intervertebral disc and spinal ligaments, mechanisms contributing to spinal stability are now thought to include neural and muscular elements. Lumbar muscles capable of generating intersegmental stiffness are considered necessary for the control of multi-planar segmental spinal motion. The transversus abdominis, psoas, quadratus lumborum and multifidus have each been described functionally as contributing to segmental motion control in the lumbar spine. However, the fundamental anatomy of these muscles has not been fully established nor have their architectural characteristics as a functional group been explored. A dissection of the lumbar spine was undertaken to document the attachments of the deep vertebral muscles and illustrate their group architectural characteristics in the context of multi-planar segmental motion. The transversus abdominis, psoas, quadratus lumborum and multifidus were each noted to have segmental attachment patterns in the lumbar spine. As a group, they surround the lumbar motion segments from the anterolateral aspect of a vertebral body to the spinous process. A hypothetical role for this muscle group in maintaining lumbar spine stability is discussed as are suggestions for future research.

Abdominal Muscles↗
PubMed2006

Recruitment of the deep cervical flexor muscles during a postural-correction exercise performed in sitting.

Specific strategies to optimally facilitate postural muscles to retrain postural form are advocated in the clinical management of neck pain. The purpose of this study was to compare the activation of selected cervical, thoracic and lumbar muscles during independent and facilitated postural correction in sitting in 10 subjects with chronic neck pain. Deep cervical flexor (DCF) muscle activity was recorded with custom electrodes inserted via the nose and fixed by suction to the posterior mucosa of the oropharynx. Surface electrodes were placed over the thoracic erector spinae and lumbar multifidus muscles. Root-mean-square EMG amplitude was measured for each muscle across two conditions. In the first condition, subjects were instructed to spontaneously "sit up straight" from a slumped posture without any other guidance from the therapist. In the second condition the therapist provided specific manual and verbal facilitation to assist the patient to correct to an upright pelvic position with a neutral spinal lumbo-pelvic position. Activation of the DCF and lumbar multifidus muscles (P<0.05) were significantly greater when the therapist facilitated postural correction compared to independent sitting correction. Specific postural-correction strategies result in better facilitation of key postural muscles compared to non-specific postural advice. The results of this study highlight the need for clinical skill and precision in postural training of patients with neck pain.

Adult↗
PubMed2005

Back muscle activation pattern and spectrum in defined load situations.

For the prevention and rehabilitation of low back pain the understanding muscle function in the low back region is essential. Important aspects of function include the muscle activation patterns and muscle fatigue. In the low back region m. erector spinae plays a critical role. The different parts of this muscle complex differ considerably in function. Following the concept of Bergmark [A. Bergmark, Stability of the lumbar spine, Acta Orthop. Scand. 60 (1989) 1-54] trunk muscles can be divided in two subsystems, the global-mobilizing-system and the local-stabilizing-system. At present the multifidus muscles are assigned to the local whereas the longissimus and iliocostalis muscles are assigned to the global system. From results of the four parts of our investigation, it can be shown that essential information about muscle function can be obtained by spectral and intra- as well as inter-muscular surface EMG parameters. Obtained data demonstrated functional transitions between the local and global system of trunk muscles for the multifidus muscle.

Journal Article↗
PubMed2006

Changes of low back pain after vascular reconstruction for abdominal aortic aneurysm and high aortic occlusion: a retrospective study.

BACKGROUND: The purpose of the present study is to clarify the influence of acute and chronic interruption of blood flow from lumbar arteries as well as the influence of vascular reconstruction on low back pain, back muscles, and lumbar discs. METHODS: Subjects were 34 patients with AAA in whom vascular reconstruction was performed. A second group was comprised of 9 patients with HAO. The presence of low back pain before surgery and at follow-up examination was retrospectively examined in the AAA group and the HAO group to investigate postoperative changes. The CSA and degeneration of the multifidus muscle and the lumbar discs on magnetic resonance imaging were assessed in the AAA group and control group. RESULTS: Low back pain, significant atrophy, or degeneration of the multifidus muscle or degeneration of the lumbar disc did not newly develop after surgery in the AAA group. These results indicated that acute interruption of lumbar arteries did not induce the development or deterioration of low back pain and organic changes in the back muscles or lumbar discs. The frequency of low back pain before surgery was significantly higher in the HAO group than that in the AAA group. However, the frequency of low back pain after surgery did not differ significantly between the 2 groups because low back pain in the HAO group was improved after surgery. CONCLUSION: The finding that low back pain was improved by merely performing treatment for the vascular system might provide support for the presence of vascular backache.

Acute Disease↗
PubMed2001

Functional roles of abdominal and back muscles during isometric axial rotation of the trunk.

Electromyographic (EMG) studies have shown that a large number of trunk muscles are recruited during axial rotation. The functional roles of these trunk muscles in axial rotation are multiple and have not been well investigated. In addition, there is no information on the coupling torque at different exertion levels during axial rotation. The aim of the study was to investigate the functional roles of rectus abdominis, external oblique, internal oblique, latissimus dorsi, iliocostalis lumborum and multifidus during isometric right and left axial rotation at 100%, 70%, 50% and 30% maximum voluntary contractions (MVC) in a standing position. The coupling torques in sagittal and coronal planes were measured during axial rotation to examine the coupling nature of torque at different levels of exertions. Results showed that the coupled sagittal torque switches from nil to flexion at maximum exertion of axial rotation. Generally, higher EMG activities were shown at higher exertion levels for all the trunk muscles. Significant differences in activity between the right and left axial rotation exertions were demonstrated in external oblique, internal oblique, latissimus dorsi and iliocostalis lumborum while no difference was shown in rectus abdominis and multifidus. These results demonstrated the different functional roles of trunk muscles during axial rotation. This is important considering that the abdominal and back muscles not only produce torque but also maintain the spinal posture and stability during axial rotation exertions. The changing coupling torque direction in the sagittal plane when submaximal to maximal exertions were compared may indicate the complex nature of the kinetic coupling of trunk muscles.

Abdominal Muscles↗
PubMed2001

Median frequency of the electromyographic signal: effect of time-window location on brief step contractions.

The purpose of this study was to determine, for different back muscles, if the median frequency (MF) of the electromyographic (EMG) power spectrum changes according to the position of the time window during a 5 s step contraction. Twenty males with no known back problems were standing upright in a dynamometer allowing lower limb and pelvis stabilization. Trunk extension efforts were performed by pushing on a force platform positioned at the T4 level while the extension moment at L5/S1 was displayed as visual feedback. The EMG signals from four homologous back muscles (multifidus at L5, ilicostalis lumborum at L3, and longissimus at L1 and T10) were collected using active surface electrodes during two 5 s static step contractions performed at five force levels (10, 20, 40, 60 and 80% of the maximal voluntary contraction). The root mean square (RMS) and MF values of the EMG signals corresponding to three 250 ms time windows (beginning, middle and end of each step contraction) were computed. The RMS values of several back muscles increased from the first to the third time window for contractions performed at high force levels only. However, a concomitant decrease in the MF values was observed only for the left multifidus muscle. It was concluded that muscle fatigue does not generally manifest itself during 5 s step contractions through the EMG signal. However, it is recommended to use step contractions lasting less than 5 s and to choose a time window located in the first 1-3 s to completely eliminate the possible effects of fatigue.

Adult↗
PubMed2002

Evaluation of measurement strategies to increase the reliability of EMG indices to assess back muscle fatigue and recovery.

The purpose of this study was to assess different measurement strategies to increase the reliability of different electromyographic (EMG) indices developed for the assessment of back muscle impairments. Forty male volunteers (20 controls and 20 chronic low back pain patients) were assessed on three sessions at least 2 days apart within 2 weeks. Surface EMG signals were recorded from four pairs (bilaterally) of back muscles (multifidus at the L5 level, iliocostalis lumborum at L3, and longissimus at L1 and T10) while the subjects performed, in a static dynamometer, two static trunk extension tasks at 75% of the maximal voluntary contraction separated by a 60 s rest period: (1) a 30 s fatigue task and (2) a 5 s recovery task. Different EMG indices (based on individual muscles or averaged across bilateral homologous muscles or across all muscles) were computed to evaluate muscular fatigue and recovery. Intra-class correlation coefficient (ICC) and standard error of measurement (SEM) in percentage of the grand mean were calculated for each EMG variable. Reliable EMG indices are achieved for both healthy and chronic low back pain subjects when (1) electrodes are positioned on medial back muscles (multifidus at the L5 level and longissimus at L1) and (2) measures are averaged across bilateral muscles and/or across two fatigue tests performed within a session. The most reliable EMG indices were the bilateral average of medial back muscles (ICC range: 0.68-0.91; SEM range: 5-35%) and the average of all back muscles (ICC range: 0.77-0.91; SEM range: 5-30%). The averaging of measures across two fatigue tests is predicted to increase the reliability by about 13%. With regards to EMG indices of fatigue, the identification of the most fatigable muscle also lead to satisfactory results (ICC range: 0.74-0.79; SEM range: 21-26%). The assessment of back muscle impairments through EMG analysis necessitates the use of multiple electrodes to achieve reliable results.

Adult↗
PubMed1998

Does methocarbamol affect fatigue markers in the low-back electromyogram?

Many low-back patients undergo electromyography (EMG)-based evaluations of muscle performance but present to the clinic after being prescribed muscle relaxants. The question that needed to be addressed was, do centrally acting muscle relaxants (methocarbamol; Robaxin) affect the EMG spectral indices of muscle fatigue that are often used to assess muscle performance. Participants performed an isometric spine extension protocol involving a 30 s fatigue exertion trial, then 1 min rest, and finally a 10 s long repeat exertion trial, at a 60% maximum voluntary contraction (MVC) level of exertion. Seven men were tested on two separate days (approximately 3-7 days apart), one day while medicated (six doses) with Robaxin and on another while not medicated. Specifically, the following parameters were studied in the bilateral multifidus (L5), lower erector spinae (L3) and upper erector spinae (T9): the slope of median power frequencies (MPFs) over the duration of the trial and the initial y-intercept of the MPF. The results generally suggest that methocarbamol (Robaxin) does not have any significant affect on the EMG median power frequency of the extensors during a fatiguing contraction followed by a repeat exertion, at least in normal people (one exception was observed--one side of multifidus at L5). However, given that this appears to be the first study of its kind, and that a relatively small number of subjects were used in this study, further investigation is needed to make a definitive conclusion about the effects of this drug on the several features of the electromyogram, over a broad spectrum of the clinical population performing a wider variety of tasks.

Adult↗
PubMed2005

The effect of early isolated lumbar extension exercise program for patients with herniated disc undergoing lumbar discectomy.

OBJECTIVE: To determine the effects of a postoperative early isolated lumbar extension muscle-strengthening program on pain, disability, return to work, and power of back muscle after operation for herniated lumbar disc. METHODS: Seventy-five patients were randomized into an exercise group (20 men, 15 women) and a control group (18 men, 22 women) to perform a prospective controlled trial of a lumbar extension exercise program in patients who underwent lumbar microdiscectomy or percutaneous endoscopic discectomy. Six weeks after surgery, patients in the exercise group undertook a 12-week lumbar extension exercise program. The assessment included measures of lumbar extensor power by the MedX (Ocala, FL) lumbar extension machine, muscle mass of multifidus and longissimus (L4-L5 cross-sectional area) by computed tomography. All patients completed the visual analog scale and the Oswestry disability index to assess pain and disability, respectively. Return to work data were also investigated. RESULTS: After the exercise program, significant improvements were observed in the exercise group versus the control group for lumbar extensor power (51.67% versus 17.55%, respectively; P < 0.05), the cross-sectional area of multifidus and longissimus muscle (29.23% versus 7.2%, respectively; P < 0.05), and the visual analog scale score (2.51 versus 4.30, respectively; P < 0.05). The percentages of returning to work within 4 months after surgery were significantly greater in the exercise group than in the control group (87% versus 24%, respectively). Although this was not statistically significant (P > 0.05), the Oswestry disability index scores in the exercise group were better than that in control group (24.6 versus 30.6, respectively). CONCLUSION: These results support the positive effects of the postoperative early lumbar extension muscle-strengthening program on pain, return to work, and strength of back muscles in patients after operation of herniated lumbar disc.

Adult↗
PubMed2002

EMG activity normalization for trunk muscles in subjects with and without back pain.

PURPOSE: The aims of the present study were to examine electromyographic (EMG) activity of six bilateral trunk muscles during maximal contraction in three cardinal planes and to determine the direction of contraction that gives maximal activation for each muscle, both for healthy subjects and back-pain patients. METHODS: Twenty-eight healthy subjects and 15 back-pain patients performed maximum voluntary contractions in three cardinal planes. Surface EMG signals were recorded from rectus abdominis, external oblique, internal oblique, latissimus dorsi, iliocostalis lumborum, and multifidus bilaterally. Root mean square values of the EMG data were calculated to quantify the amplitude of EMG signals. RESULTS: For both healthy subjects and back-pain patients, one single direction of contraction was found to give the maximum EMG signals for most muscles. Rectus abdominis demonstrated maximal activity in trunk flexion, external oblique in lateral flexion, internal oblique in axial rotation, and multifidus in extension. For the latissimus dorsi and iliocostalis lumborum, maximal activity was demonstrated in more than one cardinal plane. CONCLUSION: This study has implications for future research involving normalization of muscle activity to maximal levels required in many trunk EMG studies. As the latissimus dorsi and iliocostalis lumborum demonstrate individual differences in the plane that gives maximal activity, these muscles may require testing in more than one plane.

Abdominal Muscles↗
PubMed1988

A study of the effects of bipedism and upright posture on the lumbosacral spine and paravertebral muscles of the Wistar rat.

Twenty-one bipedal rats were prepared by forelimb amputation and reared with 19 control rats. All of the bipedal rats became proficient upright walkers. There was significant anterior wedging of the lower lumbar vertebral bodies in all of the bipedal rats and four had radiographic evidence of degenerative disc disease. Five bipedal rats developed lumbosacral disc herniations, and the lumbar neural canal was significantly smaller in the bipedal population. There was no difference in radionuclide uptake between the two groups. Histochemical analysis of the psoas and multifidus muscles showed a significant shift from type I to type II fibers in the psoas and from type II to type I fibers in the multifidus in the bipedal population. These results indicate that upright posture places considerable stress on the lumbosacral spine and paravertebral muscles of the rat.

Amputation, Surgical↗
PubMed1992

A universal model of the lumbar back muscles in the upright position.

A model of the lumbar back muscles was constructed incorporating 49 fascicles of the lumbar erector spinae and multifidus. The attachment sites and sizes of fascicles were based on previous anatomic studies, and the fascicles were modeled on radiographs of nine normal volunteers in the upright position. Calculations revealed that the thoracic fibers of the lumbar erector spinae contribute 50% of the total extensor moment exerted on L4 and L5; multifidus contributes some 20%; and the remainder is exerted by the lumbar fibers of erector spinae. At upper lumbar levels, the thoracic fibers of the lumbar erector spinae contribute between 70% and 86% of the total extensor moment. In the upright posture, the lumbar back muscles exert a net posterior shear force on segments L1 to L4, but exert an anterior shear force on L5. Collectively, all the back muscles exert large compression forces on all segments. A force coefficient of 46 Ncm-2 was determined to apply for the back muscles. These results have a bearing on the appreciation of the effects on the back muscles of surgery and physiotherapy.

Adult↗
PubMed1997

Interaction between the porcine lumbar intervertebral disc, zygapophysial joints, and paraspinal muscles.

STUDY DESIGN: A porcine model was used to study whether muscular activation in the paraspinal muscles caused by nerve stimulation in the anulus fibrosus of a lumbar intervertebral disc could be altered by saline injection into the zygapophysial (facet) joint. OBJECTIVES: To elucidate possible mechanisms regarding the nerve pathways and interactions between the intervertebral disc, zygapophysial joints, and the paraspinal musculature. SUMMARY OF BACKGROUND DATA: The physiologic basis for chronic low back pain, including muscular spasm, is uncertain. Although extensive research involving the lumbar motion segments and the surrounding tissues has been performed, the neuromuscular connection has not been sufficiently investigated. MATERIALS AND METHODS: Twenty-three adolescent pigs were used to measure the electromyographic response in the paraspinal musculature to electrical stimulation of the posterolateral L3-L4 anulus fibrosus, before and after introduction of physiologic saline into the zygapophysial joint. Motor unit action potentials were recorded using three sets of needle electrodes placed into the deepest fascicles of the multifidus, bilateral to the L4 and L5 spinous processes, and into the central longissimus musculature, bilateral to the L4 spinous process. RESULTS: Stimulation of the nerves within the posterolateral anulus of the disc elicited reactions in the paraspinal muscles, namely the lumbar multifidus and longissimus. Introduction of physiologic saline into the zygapophysial joint resulted in a reduction in the motor unit action potential amplitude. This reduction was manifested as an immediate and constant reduction, a graded reduction, or a delayed reaction, during which the reduction occurred an average of 5 minutes after the saline injection. CONCLUSIONS: Introduction of physiologic saline into the zygapophysial joint reduced the stimulation pathway from the intervertebral disc to the paraspinal musculature. The zygapophysial joints may therefore have a regulating function, controlling the intricate neuromuscular balance in the lumbar motion segment.

Action Potentials↗
PubMed1997

Evaluation of specific stabilizing exercise in the treatment of chronic low back pain with radiologic diagnosis of spondylolysis or spondylolisthesis.

STUDY DESIGN: A randomized, controlled trial, test--retest design, with a 3-, 6-, and 30-month postal questionnaire follow-up. OBJECTIVE: To determine the efficacy of a specific exercise intervention in the treatment of patients with chronic low back pain and a radiologic diagnosis of spondylolysis or spondylolisthesis. SUMMARY OF BACKGROUND DATA: A recent focus in the physiotherapy management of patients with back pain has been the specific training of muscles surrounding the spine (deep abdominal muscles and lumbar multifidus), considered to provide dynamic stability and fine control to the lumbar spine. In no study have researchers evaluated the efficacy of this intervention in a population with chronic low back pain where the anatomic stability of the spine was compromised. METHODS: Forty-four patients with this condition were assigned randomly to two treatment groups. The first group underwent a 10-week specific exercise treatment program involving the specific training of the deep abdominal muscles, with co-activation of the lumbar multifidus proximal to the pars defects. The activation of these muscles was incorporated into previously aggravating static postures and functional tasks. The control group underwent treatment as directed by their treating practitioner. RESULTS: After intervention, the specific exercise group showed a statistically significant reduction in pain intensity and functional disability levels, which was maintained at a 30-month follow-up. The control group showed no significant change in these parameters after intervention or at follow-up. SUMMARY: A "specific exercise" treatment approach appears more effective than other commonly prescribed conservative treatment programs in patients with chronically symptomatic spondylolysis or spondylolisthesis.

Adult↗
PubMed1999

Effect of paraspinal muscle vibration on position sense of the lumbosacral spine.

STUDY DESIGN: A two-group experimental design with repeated measures on one factor was used. OBJECTIVES: To investigate the role of the muscle spindles of the paraspinal muscles in lumbosacral position sense of healthy individuals. SUMMARY OF BACKGROUND DATA: Muscle spindles are recognized to be important mediators for position and movement sense in peripheral joints, and they are very sensitive to mechanical vibration. However, little is known about their role in the control of lumbosacral spine positioning. METHODS: Twenty-five young individuals with no low back pain were assigned at random to an experimental or control group. Proprioceptive information of the multifidus muscle spindles was distorted in half of the trials in 16 individuals by manually applying vibration (70 Hz, 0.5 mm amplitude) for approximately 5 seconds. The control group (n = 9) only heard the vibrator noise during repositioning of the lumbosacral spine. Repositioning accuracy in the sitting position was estimated by calculating the mean absolute error, constant error, and variable error among six criteria and reproduction sacral tilt angles. RESULTS: Multifidus muscle vibration induced a significant muscle lengthening illusion through which the members of the experimental group undershot the target position (F(1,15) = 30.77, P < 0.0001). The position sense scores of the control group displayed no significant differences across trials (F(1,8) = 0.56, P > 0.05). CONCLUSIONS: The findings suggest that precise muscle spindle input of the paraspinal muscles is essential for accurate positioning of the pelvis and lumbosacral spine in a sitting posture.

Adult↗