Torso Muscle Research Articles

Differentiated correction of junior school age children’s posture at physical culture trainings

Purpose: to show peculiarities of differentiated correction of junior school age children’s posture, considering tonic vibration reflex. Material: the research was conducted with participation of 62 junior school age children (7-10 years old boys and girls). All children have no sport training experience. All children were preliminary examined by qualified medical doctors. Tonic vibration reflex of lumbar spine was registered. Children fulfilled test exercises, which characterized power endurance of abdomen muscles, side of torso and back muscles. Results: external signs of posture disorders were absent in frontal plane. In 35 persons (65.8%) we registered one-side increased reflex excitability of nervous centers: from right side of backbone - in 28 children (72%); from the left side in 17 children (28%). Correction of posture with the help of correcting exercises can give steady effect only with simultaneous formation of correct posture habit. For this purpose it is necessary to create muscular-joint sense of separate body parts’ position. Conclusions: for determination of functional potentials of in-born muscular corset it is recommended to fulfill special test exercises. For local influence on lumbar spine muscles it is recommended to use exercise of asymmetric character.

SELECTION OF MUSCLE GROUPS FOR SURFACE ELECTROMYOGRAPHY (SEMG) MEASUREMENT IN ANALYZING MOTORCYCLING ACTIVITY

While riding motorcycle have become a popular mode of transportation in most parts of the world, increase in motorcycle road accidents are very alarming. Many factors have been found to cause such motorcycle accidents and among others is motorcyclist fatigue. The aim of this study is to identify muscle groups that are related to motorcycling activity that may lead to motorcyclist muscle fatigue especially during prolonged riding. The groups of muscle recommended by this study were extracted from current literatures and studies, questionnaires and direct observation, and also a pilot surface electromyography (sEMG) experiment. Direct observation was made on motorcyclists’ hand and foot positioning during riding including their riding posture. Upon confirming the recommended muscle groups, a sEMG experiment was conducted using an established adjustable motorcycle test rig, the Postura MotergoTM. Several torso muscle groups were identified and recommended for analyzing motorcyclist muscle fatigue. However, lower extremity body muscle groups were not listed. This is due to no considerations were made by neither researchers nor being testified by participants answering the questionnaire.

Evaluating Abdominal and Lower-Back Muscle Activity While Performing Core Exercises on a Stability Ball and a Dynamic Office Chair.

The purpose of this study was to evaluate the ability of a dynamic office chair to activate the core muscles while participants performed exercises sitting on the chair compared to a stability ball. Prolonged sitting has become an accepted part of the modern office. However, epidemiological evidence suggests that sedentary postures are linked to many adverse effects on health. The concept of dynamic or active sitting is intended to promote movement while sitting to reduce the time spent in prolonged, static postures. Sixteen participants performed four pelvic rotation exercises (front-back, side-side, circular, and leg lift) on both a dynamic office chair and a stability ball. Muscle activity from 12 torso muscles were evaluated with surface electromyography. For all exercises, trunk muscle activity on the chair was comparable to that on a stability ball. The right external oblique was the only muscle to produce greater peak activity (p = .019) when using the ball compared to the chair (21.4 ± 14.0 percent maximal voluntary excitations (%MVE) and 14.7 ± 10.8 %MVE for the ball and chair, respectively). The left thoracic erector spinae produced greater average activity (p = .044) on the chair than on the ball. These findings suggest that this dynamic sitting approach could be an effective tool for core muscle activation while promoting movement and exercise while sitting at work. Muscle activations on the dynamic chair are comparable to those on a stability ball, and dynamic office chairs can promote movement and exercise while sitting at work.

Analysis of Pushing Exercises

Labile surfaces in the form of suspension straps are increasingly being used as a tool in resistance training programs. Pushing is a common functional activity of daily living and inherently part of a well-rounded training program. This study examined pushing exercises performed on stable surfaces and unstable suspension straps, specifically muscle activation levels and spine loads were quantified together with the influence of employing technique coaching. There were several main questions that this study sought to answer: Which exercises challenged particular muscles? What was the magnitude of the resulting spine load? How did stable and unstable surfaces differ? Did coaching influence the results? Fourteen men were recruited as part of a convenience sample (mean age, 21.1 ± 2.0 years; height, 1.77 ± 0.06 m; mean weight, 74.6 ± 7.8 kg). Data were processed and input to a sophisticated and anatomically detailed 3D model that used muscle activity and body segment kinematics to estimate muscle force-in this way, the model was sensitive to the individuals choice of motor control for each task; muscle forces and linked segment joint loads were used to calculate spine loads. Exercises were performed using stable surfaces for hand/feet contact and repeated where possible with labile suspension straps. Speed of movement was standardized across participants with the use of a metronome for each exercise. There were gradations of muscle activity and spine load characteristics to every task. In general, the instability associated with the labile exercises required greater torso muscle activity than when performed on stable surfaces. Throughout the duration of an exercise, there was a range of compression; the TRX push-up ranged from 1,653 to 2,128.14 N, whereas the standard push-up had a range from 1,233.75 to 1,530.06 N. There was no significant effect of exercise on spine compression (F(4,60) = 0.86, p = 0.495). Interestingly, a standard push-up showed significantly greater shear than TRX angle 1 (p = 0.02), angle 2 (p = 0.01), and angle 3 (p = 0.02). As with any training program for the elite or recreational athlete alike, specific exercises and programs should reflect one's injury history, capabilities, limitations, and training goals. Although none of the exercises examined here breached the NIOSH action limit for compression, those exercises that produced higher loads should be used relative to the individual. Thus, the atlas of muscle activation, compression, and shear forces provided can be used to create an appropriate program. Those individuals not able to tolerate certain loads may refer to the atlas and choose exercises that minimize load and still provide sufficient muscle activation. Conversely, an individual with a resilient back that requires an increased muscular challenge may choose exercises with higher muscle activation and spine load. This helps the individual, trainer, or coach in program design respecting individual differences and training goals.

Isometric torso muscle endurance profiles in adolescents aged 15–18: normative values for age and gender differences

Objective: The aim of this study was to establish normative values for torso muscle endurance in adolescents aged 15–18 years. It was hypothesized that torso endurance profiles of adolescents differs between males and females and between adolescents and adults.Background: Decreased torso muscle endurance has been identified as a potential personal risk factor for low back pain development in both adolescents and later years together with being detrimental for athletic performance.Design: Measurement of torso muscle endurance, established through four tests performed in random order in a healthy adolescent population.Setting: High school in Novi Sad, Province of Vojvodina, Republic of Serbia.Methods: Two hundred and ninety-four adolescents from one high school (178 males and 116 females) were grouped into four age strata. Selected isometric torso muscle endurance tests were: Biering-Sørensen test for extensor endurance; Flexor endurance test; right and left Side Bridge tests. The mean, ratio, standard deviation and 25th, 50th and 75th percentile scores were determined for each gender/age strata.Results and conclusion: Males had higher lateral torso endurance than females. Adolescents in general demonstrate their peak lifetime endurance as they appear more endurable than children and comparable adult groups. These data of endurance times, their ratios and percentiles in healthy normal subjects form a database bridging existing data for children and adults that may be useful for guiding training and rehabilitation.

Does Spine Posture Affect Isometric Torso Muscle Endurance Profiles in Adolescent Children?

The purpose of this cross-sectional study was to examine mean values of isometric torso muscle profiles of four spinal postures (good posture, thoracic kyphosis, lumbar lordosis and scoliosis) among 743 children from the ages of 7 to 14 years old. It was hypothesized that having good posture, thoracic hyper-kyphosis, lumbar hyper-lordosis and scoliosis is linked to different isometric torso muscle endurance profiles. Torso muscle endurance, established through four tests (Biering-S?rensen Test for extensor endurance, Flexor Endurance Test and right and left Side Bridge Tests for lateral endurance) performed in random order and spine postural screening categorized subjectively by observation was measured. Posture was proved to be linked to endurance scores. Hyper-lordotic spines demonstrated a decreased endurance compared to the three other postures (F = 5.344; p < 0.01); pairwise comparisons confirmed these differences (p < 0.05). Trends further suggested that hyper-lordosis was detrimental in lateral chain torso endurance while a hyper-kyphotic spine was more resilient in anterior chain torso endurance. Understanding the relationship between posture and endurance may be beneficial in clinical, as well as coaching/teaching settings.

Changes in Torso Muscle Endurance Profiles in Children Aged 7 to 14 Years: Reference Values

Dejanovic A, Harvey EP, McGill SM. Changes in torso muscle endurance profiles in children aged 7 to 14 years: reference values. ObjectiveTo establish torso muscle endurance values in children aged 7 to 14 years, as well as ratios between torso extensors, flexors, and lateral torso flexors, with applications in clinical assessment, rehabilitation, physical education targets, and athletic training program designs. It was hypothesized that boys and girls mature differently in terms of torso muscle endurance. DesignMeasurements of torso muscle endurance were performed by using 4 tests in healthy children. SettingElementary school in Novi Sad, Province of Vojvodina, Republic of Serbia. ParticipantsChildren from 1 elementary school (N=753, n=394 boys and n=359 girls) were grouped into 8 age strata. InterventionsNot applicable. Main Outcome MeasuresFour tests established isometric physical endurance: Biering–Sørensen test for extensor endurance, flexor endurance test, and right- and left-side bridge tests. The mean, ratio, standard deviation, and 25th, 50th, and 75th percentile scores were determined for each sex/age stratum. ResultsA 2-way analysis of variance indicated that girls had higher mean endurance times for torso extension and torso flexion than did boys. For example, times measured by using Biering–Sørensen and right-side bridge tests were significantly greater for girls than for boys across all age groups (P<.023). Boys can sustain the side torso test longer than can girls. Furthermore, 3-dimensional torso muscle endurance is under significant impact of age. Tukey Honestly Significant Difference post hoc tests confirmed that within and between sex exist significant differences in mean endurance times in all age strata at the significance level P=.05. ConclusionBoth age and sex influence differences in torso endurance in children aged 7 to 14 years. These data of endurance times, their ratios, and percentiles in healthy subjects form a database that may be useful for providing training and rehabilitation targets.

Progressive hip rehabilitation: The effects of resistance band placement on gluteal activation during two common exercises

BackgroundA critical issue for constructing a progressive rehabilitation program is the knowledge of muscle activation levels across exercises and within exercise modifications. Many exercises are offered to enhance gluteal muscle activation during functional rehabilitation but little data exists to guide the progression of exercise intensity during rehabilitation. The objective of this paper was to examine the effects of altering resistance band placement during ‘Monster Walks’ and ‘Sumo Walks.’ MethodsNine healthy male volunteers formed a convenience sample. Sixteen electromyography channels measured neural drive of selected muscles of the right hip and torso muscles. Three resistance band placements (around the knees, ankles and feet) during the two exercises were utilized to provide a progressive resistance to the gluteal muscles while repeated measures ANOVA with Bonferroni adjustment was used to assess differences in mean EMG. The presentation of exercises and band placement were randomized. FindingsExamining muscle activation profiles in the three hip muscles of interest revealed the progressive nature of the neural drive when altering band placement. Tensor fascia latae (TFL) demonstrated a progressive activation moving the band from the knee to the distal band placement, but not between the ankle and foot placements. Gluteus medius demonstrated a progressive activation moving distally between band placements. Gluteus maximus was preferentially activated only during the foot placement. InterpretationThe band placements offered a progressive increase in resistance for hip rehabilitation, specifically the gluteal muscles. The added benefit of placing the band around the forefoot was selective enhancement of the gluteal muscles versus TFL presumably by adding an external rotation effort to the hips. This information may assist those who address gluteal activation patterns for patients suffering hip and back conditions where gluteal activation has been affected.

Do Anthropometric Measures Influence Torso Muscle Endurance Profiles of Children Aged 7 to 14?

The aim of this study was to investigate whether torso endurance scores were linked with anthropometric variables in children and to develop a normative scale of anthropometric measures in children in both genders for clinical assessment, rehabilitation, physical education targets and young athletic training purposes. It was hypothesized that changes in anthropometric measures through ages 7 to 14 influence endurance scores in both subsets. It was also hypothesized that boys and girls differ in the relationships between torso muscle endurance and anthropometric measures. Reduced torso muscle endurance has been identified as a potential personal risk factor for developing low back pain and decreased athletic performance. However, torso muscle endurance data in children is lacking. Further, given that endurance tests require postures where the body is supported horizontally, it makes sense that anthropometric variables would influence endurance. Isometric torso muscle endurance scores established through four tests were performed in random order by healthy children. These were correlated with anthropometric dimensions. Seven hundred and fifty-three children from one elementary school (394 boys and 359 girls) were grouped into 8 age strata (7 to 14). Each age stratum had different number of participants for boys and girls. Four tests established isometric torso muscle endurance: Biering-Sorensen test for extensor endurance, flexor endurance test and right and left side bridge tests. The mean, standard deviation of the endurance tests and anthropometric measures were determined for each gender/age strata. The Pearson product-moment correlation coefficients were determined between the anthropometric dimensions and isometric torso endurance scores for each gender/age strata. Variance in endurance scores were not well explained by anthropometric measures. Variables other than segment length and circumference influence torso endurance as children grow and develop. Given links to future back pain and athletic performance, more investigation would be justified.

スピードスケート短距離ジュニアおよびシニア選手における筋の形態的特徴と陸上模倣動作における関節トルク発揮能力との関係

The purpose of this study was to identify the relationship between muscle morphological characteristics and joint torque exertion ability during movements simulating speed skating in sprint speed skaters. In 10 junior and 9 senior elite male skaters who participated in the 500-m race, the cross-sectional areas (CSA) of the right thigh and torso muscles were measured using magnetic resonance imaging. Skaters performed two dry skating tests (single leg skate jump and side-jump) on a tartan track, and were videotaped using two synchronized high-speed video cameras (250 fps) with the DLT technique during the tests. The ground reaction forces (GRF) of the support right leg were measured using a force platform (500 Hz). The GRF and three-dimensional coordinates of the segment endpoints were determined in order to calculate the maximal joint torques in the lower limb using an inverse dynamics approach. Although no significant difference in the CSA of the thigh was observed between the junior and senior groups, the CSA of the torso in the senior group was significantly greater than that in the junior group (p<0.01). In the torso, the CSAs of the psoas major and quadratus lumborum in the senior group were significantly greater than those in the junior group (p<0.01 and p<0.05, respectively). During the single leg skate jump, no significant difference in the maximal joint torques in the lower limb was observed between the junior and senior groups. In contrast, during the side-jump, the maximal hip abduction and internal rotation torques in the senior group were significantly greater than those in the junior group (p<0.05 and p<0.01, respectively), whereas maximal ankle plantar flexion torque in the junior group was significantly greater than that in the senior group (p<0.05). In addition, significant positive relationships were observed between the CSA of the quadratus lumborum and maximal hip abduction and internal rotation torques during the side-jump (p<0.05). These results indicate that senior top skaters increase their maximal joint torque exertion not at the distal joint but at the proximal joint in the lower limb. It was suggested that the CSAs of the psoas major and quadratus lumborum in the torso were important factors for development of performance in sprint speed skating.

The relationship between trunk muscle activation and trunk stiffness: examining a non-constant stiffness gain

The relationship between muscle activation, force and stiffness needs to be known to interpret the stability state of the spine. To test the relationship between these variables, a quick release approach was used to match quantified torso stiffness with an EMG activation-based estimate of individual muscle stiffnesses. The relationship between activation, force and stiffness was modelled as , where k, F and l are muscle stiffness, force and length, respectively, and q is the dimensionless stiffness gain relating these variables. Under the tested experimental scenario, the ‘stiffness gain’, q, which linked activation with stiffness, demonstrated a decreasing trend with increasing levels of torso muscle activation. This highlights the likelihood that the choice of a single q value may be over simplistic to relate force to stiffness in muscles that control the spine. This has implications for understanding the potential for spine instability in situations requiring high muscular demand.

EMG in rotation–flexion of the torso

The objective of this study was to determine the magnitude and phasic relationship of the torso muscles in rotation–flexion of varying degree of asymmetries of the trunk. Nineteen normal young subjects (7 males and 12 females) were stabilized on a posture stabilizing platform and instructed to assume a flexed and right rotated posture. A combination 20°, 40° and 60° of rotation and 20°, 40° and 60° of flexion resulted in nine postures. These postures were assumed in a random order. The subjects were asked to exert their maximal voluntary isometric contraction (MVC) in the plane of rotation of the posture assumed for a period of 5 s. The surface EMG from the external and internal obliques, rectus abdominis, latissimus dorsi and erector spinae at the 10th thoracic and 3rd lumbar vertebral levels was recorded. The abdominal muscles had the least response at 40° of flexion, the dorsal muscles had the highest magnitude. With increasing right rotation, the left external oblique continued to decrease its activity. The ANOVA revealed that rotation and muscles had a significant main effect on normalized peak EMG ( p < 0.02) in both genders. There was a significant interaction between rotation and flexion in both genders ( p < 0.02) and rotation and muscle in females. The erector spinae activity was highest at 40° flexion, due to greater mechanical disadvantage and having not reached the state of flexion–relaxation. The abdominal muscle activity declined with increasing asymmetry, due to the decreasing initial muscle length. The EMG activity was significantly affected by rotation than flexion ( p < 0.02).

Individualized chiropractic and integrative care for low back pain: the design of a randomized clinical trial using a mixed-methods approach.

BackgroundLow back pain (LBP) is a prevalent and costly condition in the United States. Evidence suggests there is no one treatment which is best for all patients, but instead several viable treatment options. Additionally, multidisciplinary management of LBP may be more effective than monodisciplinary care. An integrative model that includes both complementary and alternative medicine (CAM) and conventional therapies, while also incorporating patient choice, has yet to be tested for chronic LBP.The primary aim of this study is to determine the relative clinical effectiveness of 1) monodisciplinary chiropractic care and 2) multidisciplinary integrative care in 200 adults with non-acute LBP, in both the short-term (after 12 weeks) and long-term (after 52 weeks). The primary outcome measure is patient-rated back pain. Secondary aims compare the treatment approaches in terms of frequency of symptoms, low back disability, fear avoidance, self-efficacy, general health status, improvement, satisfaction, work loss, medication use, lumbar dynamic motion, and torso muscle endurance. Patients' and providers' perceptions of treatment will be described using qualitative methods, and cost-effectiveness and cost utility will be assessed.Methods and DesignThis paper describes the design of a randomized clinical trial (RCT), with cost-effectiveness and qualitative studies conducted alongside the RCT. Two hundred participants ages 18 and older are being recruited and randomized to one of two 12-week treatment interventions. Patient-rated outcome measures are collected via self-report questionnaires at baseline, and at 4, 12, 26, and 52 weeks post-randomization. Objective outcome measures are assessed at baseline and 12 weeks by examiners blinded to treatment assignment. Health care cost data is collected by self-report questionnaires and treatment records during the intervention phase and by monthly phone interviews thereafter. Qualitative interviews, using a semi-structured format, are conducted with patients at the end of the 12-week treatment period and also with providers at the end of the trial.DiscussionThis mixed-methods randomized clinical trial assesses clinical effectiveness, cost-effectiveness, and patients' and providers' perceptions of care, in treating non-acute LBP through evidence-based individualized care delivered by monodisciplinary or multidisciplinary care teams.Trial registrationClinicalTrials.gov NCT00567333

Clinical tools to quantify torso flexion endurance: Normative data from student and firefighter populations

Given that torso muscle endurance is one of the few metrics that has been shown to be linked to having a history of back disorders together with predicting future back disorders, endurance tests for workers have been developed. While some data exists on the V-sit exercise for flexor endurance, some have specifically adopted the plank test. The primary objective of this study was to assess links between the two tests. Two data sets were collected. The first set was obtained from a convenience group of fire fighters where the plank endurance test scores, together with the Biering Sorensen test for extension endurance, were obtained over three years. The second data set was obtained from a tightly controlled cross-sectional study of university students that included scores for both flexor and extensor endurance. 620 fire fighters for the first data set and 181 university students for the second. While flexor endurance in the firefighters peaked when aged in their 40's, extensor endurance peaked in their 20's. In the study of university students, the plank scores were relatively higher than the V-sit scores in males but relatively lower than the V-sit in the females. A pearson correlation test between the paired plank and V-sit scores of each subject rendered a coefficient of r =0.34. This means that the performance on one flexor test only predicted 11% of the score in the other. ANOVA comparison of scores based on their history of having had shoulder or back troubles showed no significant link between V-sit or plank scores. The plank scores are not well correlated with the V-sit scores suggesting that the two measure different variables. Since more data exists for the V-sit, measurement of flexor endurance in occupational settings using this test probably forms a stronger link to back injury.

Torso muscle EMG profile differences between patients of back pain and control

Background Electrophysiological criteria that identify and characterize low back pain can lead to better understanding of the afliction and possibly aid in its treatment. Method Nineteen male and 22 female subjects with chronic back pain, without lumbar radiculopathy; and 30 male and 33 female control subjects with no history of low back pain in the last 12 months, were recruited into the study. All subjects flexed, extended, laterally flexed, flexed anterolaterally and extended posterolaterally isometrically to 20% and 100% of their maximal voluntary contraction (MVC). Additionally, patients were asked to do these activities to their pain threshold levels and control subjects to 60% maximum voluntary contraction. Surface electromyograms (EMG) were recorded from lumbar erectores spinae, external obliques and rectus abdominis bilaterally. The electromyogram was subjected to magnitude, Fast Fourier Transform, and wavelet analyses. The median frequency and frequency bands were calculated with their power. The wavelet decomposition was done and a logistic discriminate analysis was carried out to classify patients and normal controls. Findings The normalized peak electromyograms of patients were significantly greater than controls ( P < 0.01). The muscle conduction velocity was not disturbed by pain. Significant differences were found in total power between patients and controls ( P < 0.01). The analysis correctly classified patients and controls 65% and 98% of the time, respectively at 20% MVC, 95.1% (patients) and 86.8% (controls) at pain threshold/60% MVC, and 74.3% (patients) and 86.4% (controls) at pain tolerance/MVC ( P < 0.05). Interpretation The surface electromyography can be used in discriminating chronic low back pain patients and controls. This would be an objective test over and above other subjective tests, such as pain provocation.

Comparison of Different Strongman Events: Trunk Muscle Activation and Lumbar Spine Motion, Load, and Stiffness

Strongman events are attracting more interest as training exercises because of their unique demands. Further, strongman competitors sustain specific injuries, particularly to the back. Muscle electromyographic data from various torso and hip muscles, together with kinematic measures, were input to an anatomically detailed model of the torso to estimate back load, low-back stiffness, and hip torque. Events included the farmer's walk, super yoke, Atlas stone lift, suitcase carry, keg walk, tire flip, and log lift. The results document the unique demands of these whole-body events and, in particular, the demands on the back and torso. For example, the very large moments required at the hip for abduction when performing a yoke walk exceed the strength capability of the hip. Here, muscles such as quadratus lumborum made up for the strength deficit by generating frontal plane torque to support the torso/pelvis. In this way, the stiffened torso acts as a source of strength to allow joints with insufficient strength to be buttressed, resulting in successful performance. Timing of muscle activation patterns in events such as the Atlas stone lift demonstrated the need to integrate the hip extensors before the back extensors. Even so, because of the awkward shape of the stone, the protective neutral spine posture was impossible to achieve, resulting in substantial loading on the back that is placed in a weakened posture. Unexpectedly, the super yoke carry resulted in the highest loads on the spine. This was attributed to the weight of the yoke coupled with the massive torso muscle cocontraction, which produced torso stiffness to ensure spine stability together with buttressing the abduction strength insufficiency of the hips. Strongman events clearly challenge the strength of the body linkage, together with the stabilizing system, in a different way than traditional approaches. The carrying events challenged different abilities than the lifting events, suggesting that loaded carrying would enhance traditional lifting-based strength programs. This analysis also documented the technique components of successful, joint-sparing, strongman event strategies.

WALKERS SWING ARMS PASSIVELY

When Herman Pontzer was a teaching assistant for an undergraduate class designed to show that shoulder muscles drive arm swinging as we walk, he was in for a surprise. The class's results showed that arms and legs weren't swinging completely out of sync, as he had expected. Also, the torso muscles

Torso and Hip Muscle Activity and Resulting Spine Load and Stability while Using the ProFitter 3-D Cross Trainer

The ProFitter 3-D Cross Trainer is a labile surface device used in the clinic and claimed to train spine stability. The purpose of this study was to quantify the spine mechanics (compression and shear forces and stability), together with muscle activation mechanics (surface electromyography) of the torso and hip, during three ProFitter exercises. Trunk muscle activity was relatively low while exercising on the device (<25%MVC). Gluteus medius activity was phasic with the horizontal sliding position, especially for an experienced participant. Sufficient spinal stability was achieved in all three exercise conditions. Peak spinal compression values were below 3400 N (maximum 3188 N) and peak shear values were correspondingly low (under 500 N). The exercises challenge whole-body dynamic balance while producing very conservative spine loads. The motion simultaneously integrates hip and torso muscles in a way that appears to ensure stabilizing motor patterns in the spine. This information will assist with clinical decision making about the utility of the device and exercise technique in rehabilitation and training programs.

Calciphylaxis: a case report

Calciphylaxis or calcific uremic arteriolopathy is characterized by the involvement of the tunica elastica of the reticular or deep subcutaneous dermis, with extravascular and vascular thrombosis calcifications that lead to tissular ischemia. The torso muscles, the lumbar region, and lower limbs are more frequently affected. The pathogenesis is unknown. Calciphylaxis is associated to hyperparathyroidism, chronic renal failure, and diabetes mellitus. The best therapy to date is prevention: early treatment of renal failure, performing a partial parathyroidectomy where necessary, surgical debridement of the necrotic tissue, as well as avoiding the trigger factors such as systemic corticosteroids.

The intrinsic stiffness of the in vivo lumbar spine in response to quick releases: Implications for reflexive requirements

Torso muscles contribute both intrinsic and reflexive stiffness to the spine; recent modeling studies indicate that intrinsic stiffness alone is sometimes insufficient to maintain stability in dynamic situations. The purpose of this study was to experimentally test this idea by limiting muscular reflexive responses to sudden trunk perturbations. Nine healthy males lay on a near-frictionless apparatus and were subjected to quick trunk releases from the neutral position into flexion or right-side lateral bend. Different magnitudes of moment release were accomplished by having participants contract their musculature to create a range of moment levels. EMG was recorded from 12 torso muscles and three-dimensional lumbar spine rotations were monitored. A second-order linear model of the trunk was employed to estimate trunk stiffness and damping during each quick release. Participants displayed very limited reflex responses to the quick load release paradigms, and consequently underwent substantial trunk displacements (>50% flexion range of motion and >70% lateral bend range of motion in the maximum moment trials). Trunk stiffness increased significantly with significant increases in muscle activation, but was still unable to prevent the largest trunk displacements in the absence of reflexes. Thus, it was concluded that the intrinsic stiffness of the trunk was insufficient to adequately prevent the spine from undergoing potentially harmful rotational displacements. Voluntary muscular responses were more apparent than reflexive responses, but occurred too late and of too low magnitude to sufficiently make up for the limited reflexes.