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At least 181 records · Page 10Linked to original sources

PubMed2001

Reproducibility and validity of a new test protocol for measuring isokinetic trunk extension strength.

OBJECTIVE: To investigate the reproducibility and validity of isokinetic trunk extension strength scores obtained using a range of motion of 20 degrees and velocities of 10 and 40 degrees /s. BACKGROUND: Common protocols for testing trunk extension strength incorporate a range of motion of 40 degrees or more and test velocities of between 30 and 180 degrees/s. These test parameters may be neither necessary for portraying the strength profile of the muscles involved nor suitable for patients impaired with low back dysfunction. DESIGN: Test-retest of maximal concentric and eccentric isokinetic trunk extension strength in healthy subjects. METHODS: 17 women and 18 men were tested twice within 1-2 weeks. Tests were performed with subjects positioned in sitting. RESULTS: The trunk extension strength scores revealed excellent agreement with the expected physiological moment-velocity curve. On average women's trunk extension strength was 62% that of men (range: 59.3-64.4%). The test-retest correlation coefficients were generally higher in women (0.70-0.87) than in men (0.52-0.78) and significant at P=0.01. The standard error of measurement ranged between 13 and 21 N m for women and between 35 and 50 N m for men, which were equivalent to 9% and 15% of the mean strength in women and men, respectively. CONCLUSION: This study indicates that the present protocol may be validly applied in assessing trunk extension strength in normal women. RELEVANCE: Reproducible and valid trunk extension strength findings are essential if measurable strength deficiency of the extensors is to be formally accepted as an impairment. The present protocol incorporates or meets most of the relevant problems associated with trunk concentric and eccentric strength testing, and hence has the potential of becoming a standard method for clinical applications.

Adult↗

PubMed2001

Trunk posture and spinal stability.

OBJECTIVE: The influence of trunk posture on musculoskeletal stability of the spine was investigated. DESIGN: A biomechanical model was developed to evaluate the influence of posture on spinal stability. Model performance was assessed by comparing predicted muscle recruitment patterns with measured EMG activity from the trunk muscles during static lifting exertions. METHOD: An inverted double-pendulum model of the spine controlled by 12 muscle equivalents of the trunk was implemented to determine spinal load and stability. Model input included trunk posture and lifted mass, output included muscle recruitment patterns necessary to achieve stability of the spine and spinal load. EMG activity recorded from the trunk muscles of 10 subjects were recorded during static exertions in various trunk flexion and asymmetric postures to compare with model output. Stable spinal load was examined as a function of trunk flexion and asymmetry during the lifting exertions. RESULTS: Antagonistic co-contraction was necessary to achieve spinal stability, particularly in upright postures. Stable spinal load was increased in asymmetric postures as a result of antagonistic muscle recruitment, suggesting greater neuromuscular control is necessary to maintain stability in asymmetric lifting postures. As trunk flexion angle increased, stability improved but spinal load was greater. CONCLUSIONS: Results illustrate that muscle recruitment patterns are more accurately explained by stability than by equilibrium alone. Spinal stability is influenced by posture. Specifically, control of spinal stability is reduced in asymmetric postures associated with low-back disorder risk. RELEVANCE: Traditional assessment of low-back disorder risk have focussed on spinal loading. Results illustrate that postural risk factors for low-back pain may be partially attributable to stability considerations.

Adult↗

PubMed2002

The influence of fatigue on trunk muscle responses to sudden arm movements, a pilot study.

OBJECTIVE: To examine fatigue induced changes in trunk muscle latencies following trunk muscle fatigue. DESIGN: A repeated measures within subject design.Background. Trunk muscle responses to sudden movements is of interest in clinical biomechanics and motor control. METHODS: Electromyographic profiles were recorded from transversus abdominis (finewire), internal oblique, rectus abdominis and external oblique and longissimus at the level of the 3rd lumbar vertebrae bilaterally. Four asymptomatic subjects performed arm-raising task using a visual cue before and after an isometric fatiguing trunk extension task. RESULTS: Feed-forward responses were not detected in all muscles for every trial. In general, following fatigue trunk muscle onset latencies occur earlier (left, P=0.0016; right, P=0.0475). CONCLUSIONS: Trunk muscle fatigue alters anticipatory postural adjustments in normal subjects. It remains unclear if there is a pattern for specific muscles changes between individuals and if these are reflected in individuals with low back pain. RELEVANCE: Trunk muscle fatigue and altered trunk muscles latencies to movement perturbations have been associated with low back pain. These findings suggest that there may be a link between centrally mediated response to isometric muscle fatigue and anticipatory motor control strategies.

Abdominal Muscles↗

PubMed1998

Coordination between the lumbar spine lordosis and trunk angle during weight lifting.

OBJECTIVE: To analyze the coordination of the lumbo-sacral angle (lumbar spine lordosis) and the trunk inclination during lifting of different loads. STUDY DESIGN: Kinematic data of spine motion were analyzed. The parameters characterizing the relationships between the lordosis and the trunk inclination angle were estimated. BACKGROUND: The shape of the spine has been analyzed mostly for static or quasi-static conditions. The parameters relating the lumbar spine lordosis and trunk inclination in dynamics have not been analyzed. METHODS: Healthy subjects performed unconstrained weight lifts from ground to mid-thigh level. Kinematic data were derived from the tracking of markers (light-emitted diodes) placed over the spine and pelvis using an OPTPTRAK system. The relationship between lordosis and trunk inclination was analyzed. RESULTS: The relationship between lumbar spine curvature (lumbo-sacral angle or lordosis) and trunk inclination during weight lifting was described by an exponential function with three parameters. These were the lordosis extremes associated with the horizontal and vertical positions of the trunk and the trunk inclination when lordosis equals zero. The absolute value of the lordosis angle decreases at the onset of the extension phase of lifting when the load increases, implying active reaction of musculosceletal system to increasing load. CONCLUSIONS: The changes in the lordosis and trunk inclination are strictly correlated implying that the nervous system actively coordinates the degrees of freedom of the spine, providing an inter-joint synergy.

Journal Article↗

PubMed2002

Inverse relationship between the changes in trunk lean and fat mass during gonadotropin-releasing hormone agonist therapy.

OBJECTIVE: The aim of the present study was to investigate the relationship between the changes in lean and fat mass during gonadotropin-releasing hormone agonist (GnRH agonist) therapy. METHODS: Subjects were 24 premenopausal women (mean age, 39.5+/-9.4 years; range, 32-52 years) with uterine leiomyomas. They were given GnRH agonist (leuprorelin acetate, 3.75 mg) monthly for 4 months. Age and height were recorded. Body weight, regional and total body composition, and the ratio of trunk fat mass to leg fat mass (trunk-leg fat ratio) were assessed by whole body scanning with dual-energy X-ray absorptiometry. Changes in these variables were investigated. Relationships between the changes in regional lean and fat mass were investigated using Pearson's correlation test. RESULTS: Trunk fat mass significantly increased from 8616+/-3538 to 9265+/-3526 g (P<0.01) and trunk-leg fat ratio significantly increased (1.02+/-0.39 to 1.07+/-0.39, P<0.05). Trunk lean mass significantly decreased from 18,509+/-2602 to 17,916+/-2402 g (P<0.01). However, body weight, and lean and fat mass component in the extremities did not change. Change in trunk fat mass was inversely correlated with change in trunk lean mass (r=-0.439, P<0.05), but such relationships were not observed in arm and leg regions. CONCLUSION: Inverse relationship between the changes in trunk lean and fat mass is observed during GnRH agonist therapy.

Absorptiometry, Photon↗

PubMed2000

Three dimensional preparatory trunk motion precedes asymmetrical upper limb movement.

Three-dimensional trunk motion, trunk muscle electromyography and intra-abdominal pressure were evaluated to investigate the preparatory control of the trunk associated with voluntary unilateral upper limb movement. The directions of angular motion produced by moments reactive to limb movement in each direction were predicted using a three-dimensional model of the body. Preparatory motion of the trunk occurred in three dimensions in the directions opposite to the reactive moments. Electromyographic recordings from the superficial trunk muscles were consistent with preparatory trunk motion. However, activation of transversus abdominis was inconsistent with control of direction-specific moments acting on the trunk. The results provide evidence that anticipatory postural adjustments result in movements and not simple rigidification of the trunk.

Adult↗

PubMed2000

An application of pattern recognition for the comparison of trunk muscles EMG waveforms between subjects with and without chronic low back pain during flexion-extension and lateral bending tasks.

The purpose of the study was twofold: (1) to evaluate the reliability of distance measures computed from a principal component analysis (PCA) of electromyographic (EMG) waveforms of trunk muscles recorded during standardized trunk movements and (2) to evaluate their sensitivity to the load lifted, the trunk range of motion (ROM) and to low back status. Thirty-three male subjects (18 normals, 15 suffering from non specific CLBP) aged between 35-45 years participated. The EMG signals from 12 trunk muscles and the kinematics of trunk segments were recorded during 12 tasks. The subjects performed flexion-extension and lateral bending (left and right) tasks (three complete cycles) with and without a 12 kg load and at different trunk ROM (maximal or at defined submaximal angles). Distance measures locating each subject relative to a reference PCA model were computed for each muscle and task. The reliability of these distance measures was evaluated for 10 subjects (five normals and five CLBP) who performed two tasks on three different days. The reliability of distance measures was acceptable for agonist muscles only. The distance measures were sensitive to the load lifted and to the trunk ROM for different muscles and tasks but poorly sensitive to low back status. Several reasons that could explain the low sensitivity of these measures to low back status are discussed and potential solutions are proposed. A procedure based on a reliability analysis is proposed to select the number of principal components to include in the reference PCA model. It is expected that the refinement of the method used in this study could provide an effective clinical tool to assess EMG waveforms of trunk muscles during dynamic tasks.

Biomechanical Phenomena↗

PubMed1989

Exploration of mechanical and electromyographic responses of trunk muscles to high-intensity resistive exercise.

The purposes of this study were to determine the effects of high intensity exercise on fatigue of the trunk muscles within a test session, and on multiple kinetic and electromyographic (EMG) variables over a 6-week training period. Fourty-five normal men and women (20-40 years of age) completed the study. The KIN/COM trunk testing unit (Chattecx Corporation, Chattanooga, Tennessee) was used for both testing and training. The results of the study follow: 1) The KIN/COM trunk testing system was very accurate, and the method used was highly reproducible for the kinetic variables. Reproducibility for the endurance variables was mixed, and isolated EMG variables were poor. 2) Kinetic and EMG decrements associated with fatigue did occur in the trunk muscles with ten continuous cycles of maximal concentric and eccentric contractions. 3) Trunk muscle strength gains were highest for the same mode of exercise used in training (specificity), but significant strength gains also were seen in different modes of muscle contraction (transfer of training). For the trunk extensors, the eccentric form of exercise was superior. 4) The rate of isometric torque development and decay was increased by exercise in men. 5) Trunk muscle endurance was retained when gains in strength occurred. 6) The majority of variables reflecting strength and endurance were retained. The methods and results can serve as guidelines for the evaluation of trunk muscle function and resistive exercise in the clinic.

Abdominal Muscles↗

PubMed1995

Measurement of muscle strength of the trunk and the lower extremities in subjects with history of low back pain.

STUDY DESIGN: Isokinetically measured muscle strength of the trunk and lower extremities was analyzed. OBJECTIVES: The causes of the weak trunk muscle strength of subjects with low back pain were studied. SUMMARY OF BACKGROUND DATA: Although it is a commonly accepted conclusion that subjects with low back pain have weaker trunk muscles than the normal population, there are no reports concerning muscle strength of the lower extremities in subjects with low back pain. METHODS: Ninety-eight male volunteers were divided into control groups and groups with low back pain. The total trunk strength and total knee strength were defined as the sum of the peak torques of trunk extension, flexion and rotation, and of bilateral knee extension and flexion, respectively. RESULTS: The total trunk and knee strength in the group with low back pain (281 +/- 170 and 301 +/- 132 Nm) were significantly lower than in the control group (543 +/- 124 and 441 +/- 123 Nm). The total trunk and knee strength were linearly correlated in both groups (r = 0.67 and 0.79). CONCLUSIONS: In the group with low back pain, the muscles of the trunk and the lower extremities were similarly affected; this can be attributed to generalized muscular weakness or psychologic factors, such as fear of injury.

Adolescent↗

PubMed2004

The influence of spine and trunk deformity on preoperative idiopathic scoliosis patients' health-related quality of life questionnaire responses.

STUDY DESIGN: Retrospective case series. OBJECTIVES: To determine the influence of spine and trunk deformity on preoperative idiopathic scoliosis patients' health-related quality of life questionnaire responses. SUMMARY OF BACKGROUND DATA: Management recommendations for patients with idiopathic scoliosis during adolescence are based heavily on spine deformity and to some extent trunk deformity magnitude. However, the manner in which these objective measures influence the patients' perception of their condition is unclear. METHODS: Of 67 consecutive preoperative patients, 61 (91%) had completed the Scoliosis Research Society-22 health-related quality of life questionnaire and had been studied with posterior exposure surface topography. Their average age was 15 years, 6 months (range 10 years, 10 months-20 years, 10 months), and the average maximum Cobb was 63 degrees (range 40-137 degrees). Correlations between spine and trunk deformity measures and Scoliosis Research Society-22 scores were determined by the Pearson correlation coefficient, with P < 0.01 considered significant. RESULTS: For the study group, spine deformity (Cobb) correlated significantly only with Scoliosis Research Society-22 function (r = -0.39, P = 0.0022) domain. Neither coronal nor transverse plane trunk deformity composite scores correlated with any Scoliosis Research Society-22 scores. The Hump Index component of the transverse plane Suzuki Hump Sum composite score was the only trunk measurement to correlate significantly (function r = -0.45, P = 0.003; self image, r = -0.36, P = 0.0040). The strongest correlations occurred when the single thoracic curves, King classifications III and IV, were combined: Cobb versus function r = -0.53, P = 0.0027; Cobb versus self-image r = -0.46, P = 0.0099; and Hump Index versus function r = -0.60, P = 0.0005. There were no significant correlations between either spine deformity or any trunk deformity measure with Scoliosis Research Society-22 responses for either the double or thoracolumbar curve pattern groups. CONCLUSION: Both spine and upper thoracic transverse plane trunk deformity significantly influenced preoperative idiopathic scoliosis patients' perception of function and self-image, but not pain or mental health. However, in spite of a fairly rigorous standard of proof, P < or = 0.01, the significant r values ranged from -0.33 to -0.68, suggesting that there are factors other than spine and trunk deformity influencing the idiopathic scoliosis patients' health-related quality of life questionnaire responses. Future studies are necessary to define these factors.

Abdomen↗

PubMed2002

Maintenance of the celiac trunk with the left-sided liver allograft for in situ split-liver transplantation.

BACKGROUND: It has been shown that in situ split-liver transplantation (SLT) expands the cadaveric donor pool, decreases recipient waiting time, and decreases pretransplant morbidity. However, the technique as previously described requires a microvascular left hepatic artery anastomosis. In an attempt to decrease the incidence of hepatic artery thrombosis and to increase collaboration among transplant teams, in the current report, we describe a modification of the in situ SLT technique that maintains the celiac trunk with the left-sided liver allograft. METHODS: Twelve in situ split-liver procurements resulted in 24 segmental liver allografts; 11 right trisegments, 11 left lateral segments, 1 right lobe, and 1 left lobe. The common bile duct and main portal vein were maintained with the right-sided liver allograft in all cases. The right hepatic artery was divided, and the celiac trunk was maintained with the left-sided liver allograft in nine cases. In one case the left hepatic artery was divided and the celiac trunk was maintained with the right-sided allograft. Two of the 12 donors had a completely replaced left hepatic artery originating from the left gastric artery, which was divided at its origin from the celiac trunk. When the celiac trunk was maintained with the left-sided allografts, arterial reconstruction of the right-sided allograft was performed with an external iliac arterial interposition graft. Nineteen of the 24 split-liver allografts were transplanted at our center. The remaining five liver allografts were shared with regional liver transplant centers. RESULTS: In this series, 1-year actuarial patient and allograft survival rates are 100% and 96%, respectively. Hepatic artery thrombosis (HAT) did not occur in any patient receiving a left-sided split allograft in which the celiac trunk or left gastric artery was maintained; in addition, HAT did not occur in any of the right-sided allografts. HAT did occur immediately after transplantation in the one patient who was transplanted with a left lateral segment without the celiac trunk. This allograft was salvaged by early thrombectomy and interposition grafting. One patient required retransplantation, owing to portal vein thrombosis. Hepatic venous outflow obstruction did not occur in any of the patients. Two patients required reexploration in the posttransplant period because of arterial anastomotic site bleeding, and one of the left lateral segment allograft recipients had a cut-surface bile leak, which was managed nonoperatively. All of the patients are alive and well, including the five patients who received their transplants at other centers, with a median follow-up of 10 months (range, 1-27 months). CONCLUSIONS: In summary, our data demonstrate that maintaining the celiac trunk with the left-sided allograft in SLT provides excellent early survival results with low complication rates. This technical modification obviates the need for a left hepatic artery microvascular anastomosis and should lower the incidence of hepatic artery thrombosis in the small-caliber left hepatic artery. We have also shown that this technique allows sharing among liver transplant centers without compromise in patient or allograft survival rates. It is hoped that this modification in SLT will increase the number of livers split, and will promote sharing among transplant centers to truly optimize the number of liver allografts available from the cadaveric pool.

Adolescent↗

PubMed2003

Trunk sway measures of postural stability during clinical balance tests in patients with chronic whiplash injury symptoms.

STUDY DESIGN: Trunk sway occurring during clinical stance and gait tasks was compared between a group of subjects with a chronic whiplash injury, resulting from an automobile collision, and a normal collective. OBJECTIVES: To examine if population specific trunk sway patterns for stance and gait could be identified for chronic whiplash injury patients. SUMMARY OF BACKGROUND DATA: Our previous work has established that it is possible to identify specific patterns of stance and gait deficits for vestibular loss (both acute and compensated) patients and those with Parkinson's disease. Our question was whether it was possible to use the same stance and gait tasks to identify patterns of trunk sway differences with respect to those of healthy subjects and individuals with a chronic whiplash injury. METHODS: Twenty-five subjects with history of whiplash injury and 170 healthy age-matched control subjects participated in the study. Trunk sway angular displacements in chronic whiplash patients were assessed for a number of stance and gait tasks similar to those of the Tinetti and Clinical Test of Sensory Interaction and Balance (CTSIB) protocols. We used a lightweight, easy-to-attach, body-worn apparatus to measure trunk angular displacements and velocities in the roll (lateral) and the pitch (forward-backward) planes. RESULTS: Data analysis revealed several significant differences between the two groups. A pattern could be identified, showing greater trunk sway for stance tasks and for complex gait tasks that required task-specific gaze control such as walking up and down stairs. Trunk sway was less, however, for simple gait tasks that demanded large head movements but no task-specific gaze control, such as walking while rotating the head. CONCLUSIONS: Subjects who have a chronic whiplash injury show a characteristic pattern of trunk sway that is different from that of other patient groups with balance disorders. Balance was most unstable during gait involving task-specific head movements which possibly enhance a pathologic vestibulo-cervical interaction.

Abdomen↗

PubMed2004

Fast development of high intra-abdominal pressure when a trained participant is exposed to heavy, sudden trunk loads.

STUDY DESIGN: This study focused on intra-abdominal pressure (IAP) during sudden trunk loads. Ten participants were exposed to heavy, sudden trunk loads as they might occur during patient handling. OBJECTIVES: The aim was to study the development of intra-abdominal pressure when well-trained participants cope with heavy, sudden trunk loads. It is hypothesized that high IAP develops sufficiently fast to be present when the large torques act on the low-back structures. SUMMARY OF BACKGROUND DATA: Well-trained sportsmen expose themselves to heavy sudden loads of the trunk without getting injured, but it is unknown how they cope with these loads. Do they use IAP? IAP is believed to play a significant role in spine stability, but this has only been documented in experimental studies with light trunk loads. MATERIALS AND METHODS: Ten well-trained judo and jujitsu fighters were exposed to heavy sudden trunk loads through imitated patient handling situations in which the patient fell, and the fighters were to hold the patient and prevent the fall. IAP was measured with a catheter in the stomach. Along with the IAP measurement, the load on the low back during the patient falls was quantified by a three-dimensional dynamic biomechanical calculation of the torques and the compression at the L4/L5 joint. RESULTS: High IAP developed quickly and timed in relation to the external torque when the fighters were exposed to a sudden patient fall. When the trunk load was heavy and sudden, IAP was developed to be present at the time when low-back structures had to cope with the large load. CONCLUSIONS: High IAP was developed sufficiently fast to be present when the low-back structures had to cope with the large torques released from the sudden trunk loading.

Abdomen↗

PubMed2005

Backpacks, back pain, sagittal spinal curves and trunk alignment in adolescents: a logistic and multinomial logistic analysis.

STUDY DESIGN: Cross-sectional study using logistic and multinomial logistic analysis. OBJECTIVES: To investigate the influence of backpack carrying on spinal profile shoulder and trunk. SUMMARY OF BACKGROUND DATA: No similar investigations. METHODS: A randomly selected sample of 1263 students aged 12-18 years were asked for dorsal (DP) and low back pain (LBP) during the school period and holidays. Debrunner's Kyphometer and Scoliometer were used to measure craniocervical angle (CCA), thoracic kyphosis, lumbar lordosis, and shoulder shift (BL). Upper trunk shift from plumbline were recorded. RESULTS: Girls suffer from DP more often and of much more intensity pain than boys in school period and in holidays. Backpack carrying decreased CCA and changed shoulder and upper trunk shift. Asymmetrically backpack carrying increased DP and LBP. BL-shift increased DP. DP and LBP increased with coronal trunk shift. Sagittal trunk shift increased LBP. Asymmetrically carrying of backpacks increased back pain and shoulder shift in holidays. Coronal trunk shift while carrying backpacks asymmetrically increased back pain in holidays. Asymmetric backpack carrying is associated with high intensity pain. Frontal trunk shift is associated with high intensity pain. CONCLUSION: Backpack carrying, particularly asymmetrically, results in shift of upper trunk and shoulder and cervical lordosis, which furthermore seem to increase back pain in school period and holidays. Symmetric backpack carrying is recommended.

Adolescent↗

PubMed2002

Venous anatomy of the right colon: precise structure of the major veins and gastrocolic trunk in 58 cadavers.

PURPOSE: This study was designed to describe the precise venous anatomy of the right colon, which is especially important for laparoscopic right hemicolectomy. METHODS: Fifty-eight adult cadavers were dissected to define the three major venous tributaries of the right colon: the ileocolic vein, right colic vein, and middle colic vein. Two or three middle colic veins were often present, and the biggest one was designated as the main middle colic vein. The middle colic vein and the right colic vein occasionally formed a common trunk with the right gastroepiploic vein and/or the pancreaticoduodenal vein. This common trunk was defined as the gastrocolic trunk. RESULTS: All 58 cadavers had a single ileocolic vein. All of the ileocolic veins drained into the superior mesenteric vein. The right colic vein was absent in 56.9 percent (33/58), and the other 43.1 percent had a single right colic vein. The right colic vein joined the superior mesenteric vein directly in 56 percent (14/25) and the gastrocolic trunk in 44 percent (11/25). The middle colic vein was the most variable. A single middle colic vein was present in 37.9 percent (22/58), 2 middle colic veins were present in 50 percent (29/58), and 3 middle colic veins were present in 12.1 percent (7/58). The main middle colic vein drained into the superior mesenteric vein directly in 84.5 percent (49/58), whereas 12.1 percent (7/58) drained into the gastrocolic trunk. In two cadavers, there was anomalous drainage of the main middle colic vein to the splenic vein and the inferior mesenteric vein. Forty-three accessory middle colic veins were present in total. These drained into the superior mesenteric vein in 17 cadavers and into the gastrocolic trunk in 23. The gastrocolic trunk was present in 69 percent (40/58), being formed with the right colic vein in 27.5 percent (11/40; 1 was together with an accessory middle colic vein) and with the middle colic vein in 75 percent (30/40; 7 with the main middle colic vein, 23 with the accessory middle colic vein). CONCLUSION: Venous anatomy of the right colon is highly variable. It is especially important to recognize the lack of direct drainage of the right colic vein to the superior mesenteric vein and the high frequency of the presence of plural middle colic veins and the gastrocolic trunk.

Adult↗

PubMed1995

Two functionally different synergies during arm reaching movements involving the trunk.

1. To address the problem of the coordination of a redundant number of degrees of freedom in motor control, we analyzed the influence of voluntary trunk movements on the arm endpoint trajectory during reaching. 2. Subjects made fast noncorrected planar movements of the right arm from a near to a far target located in the ipsilateral work space at a 45 degrees angle to the sagittal midline of the trunk. These reaching movements were combined with a forward or a backward sagittal motion of the trunk. 3. The direction, positional error, curvature, and velocity profile of the endpoint trajectory remained invariant regardless of trunk movements. Trunk motion preceded endpoint motion by approximately 175 ms, continued during endpoint movement to the target, and outlasted it by 200 ms. This sequence of trunk and arm movements was observed regardless of the direction of the endpoint trajectory (to or from the far target) or trunk movements (forward or backward). 4. Our data imply that reaching movements result from two control synergies: one coordinates trunk and arm movements leaving the position of the endpoint unchanged, and the other produces interjoint coordination shifting the arm endpoint to the target. The use of functionally different synergies may underlie a solution of the redundancy problem.

Arm↗

PubMed2004

Stabilization and mobility of the head and trunk in wild monkeys during terrestrial and flat-surface walks and gallops.

This study investigated the patterns of rotational mobility (> or =20 degrees ) and stability (< or =20 degrees ) of the head and trunk in wild Indian monkeys during natural locomotion on the ground and on the flat-topped surfaces of walls. Adult hanuman langurs (Semnopithecus entellus) and bonnet macaques (Macaca radiata) of either gender were cine filmed in lateral view. Whole-body horizontal linear displacement, head and trunk pitch displacement relative to space (earth horizontal), and vertical head displacement were measured from the cine films. Head-to-trunk pitch angle was calculated from the head-to-space and trunk-to-space measurements. Locomotor velocities, cycle durations, angular segmental velocities, mean segmental positions and mean peak frequencies of vertical and angular head displacements were then calculated from the displacement data. Yaw rotations were observed qualitatively. During quadrupedal walks by both species, the head was free to rotate in the pitch and yaw planes on a stabilized trunk. By contrast, during quadrupedal gallops by both species, the trunk pitched on a stabilized head. During both gaits in both species, head and trunk pitch rotations were symmetrical about comparable mean positions in both gaits, with mean head position aligning the horizontal semicircular canals near earth horizontal. Head pitch direction countered head vertical displacement direction to varying degrees during walks and only intermittently during gallops, providing evidence that correctional head pitch rotations are not essential for gaze stabilization. Head-to-space pitch velocities were below 350 deg. s(-1), the threshold above which, at least among humans, the vestibulo-ocular reflex (VOR) becomes saturated. Mean peak frequencies of vertical translations and pitch rotations of the head ranged from 1 Hz to 2 Hz, a lower frequency range than that in which inertia is predicted to be the major stabilizer of the head in these species. Some variables, which were common to both walks and gallops in both species, are likely to reflect constraints in sensorimotor control. Other variables, which differed between the two gaits in both species, are likely to reflect kinematic differences, whereas variables that differed between the two species are attributed primarily to morphological and behavioural differences. It is concluded that either the head or the trunk can provide the nervous system with a reference frame for spatial orientation and that the segment providing that reference can change, depending upon the kinematic characteristics of the chosen gait.

Animals↗

PubMed2005

Trunk muscle electromyographic activity with unstable and unilateral exercises.

The purpose of this cross-sectional study was to evaluate the effect of unstable and unilateral resistance exercises on trunk muscle activation. Eleven subjects (6 men and 5 women) between 20 and 45 years of age participated. Six trunk exercises, as well as unilateral and bilateral shoulder and chest presses against resistance, were performed on stable (bench) and unstable (Swiss ball) bases. Electromyographic activity of the upper lumbar, lumbosacral erector spinae, and lower-abdominal muscles were monitored. Instability generated greater activation of the lower-abdominal stabilizer musculature (27.9%) with the trunk exercises and all trunk stabilizers (37.7-54.3%) with the chest press. There was no effect of instability on the shoulder press. Unilateral shoulder press produced greater activation of the back stabilizers, and unilateral chest press resulted in higher activation of all trunk stabilizers, when compared with bilateral presses. Regardless of stability, the superman exercise was the most effective trunk-stabilizer exercise for back-stabilizer activation, whereas the side bridge was the optimal exercise for lower-abdominal muscle activation. Thus, the most effective means for trunk strengthening should involve back or abdominal exercises with unstable bases. Furthermore, trunk strengthening can also occur when performing resistance exercises for the limbs, if the exercises are performed unilaterally.

Abdominal Muscles↗