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At least 289 records · Page 16Linked to original sources

PubMed1982

Analysis and measurement of lumbar trunk loads in tasks involving bends and twists.

Ten subjects performed isometric weight-holding and force-resisting work tasks while standing upright, both with and without a twist of the trunk; with the trunk bent laterally; and in postures involving combinations of bending and twisting. The lumbar trunk muscle contraction forces and the lumbar spine compression and shear forces imposed by these tasks were predicted using a biomechanical model. Myoelectric activity was recorded quantitatively at eight locations over the back muscles and at four locations over the abdominal wall muscles. Correlation coefficients from 0.67 to 0.88 were found between the predicted muscle contraction forces and the measured myoelectric activities when the predictions were made so as to minimize muscle contraction force per unit area. Trunk twisting and lateral bending were found to load the spine and trunk muscles less than trunk flexion or holding of weights in front of the body.

Adult↗

PubMed1994

Quantitative interpretation of lumbar muscle myoelectric signals during rapid cyclic attempted trunk flexions and extensions.

The quantitative relationship between lumbar myoelectric signals (MES) and rapidly varying isometric trunk muscle forces was investigated. Ten young adult males were asked to cycle harmonically between attempted trunk flexion and attempted trunk extension in an upright position at rates of 0.33, 0.67 and 1.0 Hz to peak efforts of 20, 40 and 60% of maximum voluntary exertion levels. The forces voluntarily exerted against a load cell were measured and used along with acquired kinematic data to calculate the time course of the net sagittal moment at the level of the third lumbar vertebra during task performances. A 22 muscle double linear programming biomechanical model was used to predict the lumbar trunk muscle contraction forces from the calculated moments. Rectified and bidirectionally low-pass filtered myoelectric activities were acquired at the L3 level from four abdominal muscles and four back muscles. The processed MES were found to be well correlated (r > 0.90) with predicted muscle forces when the MES were time-shifted to account for electromechanical delay as well as the dynamic phase shift between muscle electrical activity and contraction force. Mean time shifts that maximized the linear MES-force relationship ranged from 111 to 218 ms, were greater for the trunk extensors than the trunk flexors and generally exhibited lateral symmetry. The corresponding approximate phase angles averaged 20 degrees at the slowest rate and 50 degrees at the fastest rate. MES-force phase angles decreased as effort level was increased indicating that the dynamic MES-force relationship is nonlinear. These results illustrate the importance of accounting for the phase lag between muscle electrical activity and force when using MES to quantify muscle loads during rapidly varying exertions.

Abdominal Muscles↗

PubMed2004

Effects of experimentally induced pain and fear of pain on trunk coordination and back muscle activity during walking.

OBJECTIVE: To examine the effects of experimentally induced pain and fear of pain on trunk coordination and erector spinae EMG activity during gait. DESIGN: In 12 healthy subjects, hypertonic saline (acute pain) and isotonic saline (fear of pain) were injected into erector spinae muscle, and unpredictable electric shocks (fear of impending pain) were presented during treadmill walking at different velocities, while trunk kinematics and EMG were recorded. BACKGROUND: Chronic low back pain patients often have disturbed trunk coordination and enhanced erector spinae EMG while walking, which may either be due to the pain itself or to fear of pain, as is suggested by studies on both low back pain patients and healthy subjects. METHODS: The effects of the aforementioned pain-related manipulations on trunk coordination and EMG were examined. Results. Trunk kinematics was not affected by the manipulations. Induced pain led to an increase in EMG variability and induced fear of pain to a decrease in mean EMG amplitude during double stance. CONCLUSIONS: Induced pain and fear of pain have subtle effects on erector spinae EMG activity during walking while leaving the global pattern of EMG activity and trunk kinematics unaffected. This suggests that the altered gait observed in low back pain patients is probably a complex evolved consequence of a lasting pain, rather than a simple immediate effect. RELEVANCE: Variability of EMG data and kinematics may explain pain-dependent alterations of motor control, which in turn might contribute to a further understanding of the development of movement impairments in low back pain.

Adaptation, Physiological↗

PubMed2006

Surface electromyography activity of trunk muscles during wheelchair propulsion.

BACKGROUND: Trunk instability due to paralysis can have adverse effects on posture and function in a wheelchair. The purpose of this study was to record trunk muscle recruitment patterns using surface electromyography from unimpaired individuals during wheelchair propulsion under various propulsion speed conditions to be able to design trunk muscle stimulation patterns for actual wheelchair users with spinal cord injury. METHODS: Fourteen unimpaired subjects propelled a test wheelchair on a dynamometer system at two steady state speeds of 0.9 m/s and 1.8 m/s and acceleration from rest to their maximum speed. Lower back/abdominal surface electromyography and upper body movements were recorded for each trial. Based on the hand movement during propulsion, the propulsive cycle was further divided into five stages to describe the activation patterns. FINDINGS: Both abdominal and back muscle groups revealed significantly higher activation at early push and pre-push stages when compared to the other three stages of the propulsion phase. With increasing propulsive speed, trunk muscles showed increased activation (P<0.0001). Back muscle activity was significantly higher than abdominal muscle activity across the three speed conditions (P<0.0005), with lower back muscles predominating. INTERPRETATION: Abdominal and back muscle groups cocontracted at late recovery phase and early push phase to provide sufficient trunk stability to meet the demands of propulsion. This study provides an indication of the amount and duration of stimulation needed for a future application of electrical stimulation of the trunk musculature for persons with spinal cord injury.

Abdominal Muscles↗

PubMed2006

Trunk-strengthening exercises for chronic low back pain: a systematic review.

OBJECTIVE: The objective of this systematic review was to determine the effect of lumbar spine-strengthening exercises on outcomes for people with chronic low back pain. METHODS: Two independent reviewers followed Cochrane Back Review Group and QUORUM Statement guidelines to complete this systematic review. Exercise effects were reported as standardized mean difference (SMD) with 95% confidence intervals. RESULTS: Thirteen high-quality randomized controlled trials were included. For chronic low back pain, trunk strengthening is more effective than no exercise on long-term pain (SMD 0.95 [0.35-1.55]; intensive trunk strengthening is more effective than less intensive on function (pooled SMD: short-term, 0.58 [0.22-0.94]; long-term, 0.77 [0.33-1.20]). Compared with physiotherapy or aerobics, effects are comparable on pain and function. Motivation strategies increase effectiveness. After disk surgery, effects are significant for function (pooled SMD: short-term, 1.08 (0.76-1.41); long-term, 0.53 (0.03-1.04). For severe degeneration, trunk strengthening is less favorable than fusion on long-term pain (SMD, -0.50 [-0.99 to -0.01]) or function (SMD, -0.76 [-1.25 to -0.26]). Intensive trunk strengthening is less effective than McKenzie exercises for pain reduction (SMD: short-term, -0.29 [-0.54 to -0.05]; long-term, -0.31 [-0.55 to -0.06]). We estimated that moderate effect sizes (0.5) indicate that approximately 50% of participants and large effect sizes (0.8) indicate that approximately 80% of participants would achieve important improvement. CONCLUSIONS: Trunk strengthening appears effective compared with no exercise. Increasing exercise intensity and adding motivation increase treatment effects. Trunk strengthening, compared with aerobics or McKenzie exercises, showed no clear benefit of strengthening. It is unclear whether observed benefits are due to tissue loading or movement repetition.

Exercise Therapy↗

PubMed2004

Trunk use and co-contraction in cerebral palsy as regulatory mechanisms for accuracy control.

In the present study, we examined whether individuals with cerebral palsy (CP) systematically vary motion of the trunk and co-contraction in the upper limb as a function of accuracy demands. Four participants with spastic tetraparesis, four with spastic hemiparesis, and four healthy controls were asked to repeatedly move a spoon back-and-forth between two target locations. The task was externally paced. In half the trials the accuracy demands were increased by filling the spoon with water. In addition, a condition in which the trunk was fixated was examined. When the movements were controlled for speed, trunk motion hardly varied as a function of accuracy. Co-contraction in the shoulder, however, was systematically higher under high-accuracy demands. Trunk fixation yielded differential group effects on the co-contraction of the shoulder muscles. It increased in control participants, tended to decrease in hemiparetic participants, and was unaffected in tetraparetic participants. Collectively, the present findings show that the increased trunk involvement and high co-contraction levels in CP should not exclusively be regarded as disorder-related phenomena. Regulation of co-contraction in the shoulder is a general strategy to cope with variations in movement-accuracy constraints, while increased trunk involvement proves a secondary reaction to these constraints.

Adolescent↗

PubMed2005

Restricted response of mesencephalic neural crest to sympathetic differentiation signals in the trunk.

Lineage diversification in the vertebrate neural crest may occur via instructive signals acting on pluripotent cells, and/or via early specification of subpopulations towards particular lineages. Mesencephalic neural crest cells normally form cholinergic parasympathetic neurons in the ciliary ganglion, while trunk neural crest cells normally form both catecholaminergic and cholinergic neurons in sympathetic ganglia. In contrast to trunk neural crest cells, mesencephalic neural crest cells apparently fail to express the catecholaminergic transcription factor dHAND in response to BMPs in the head environment. Here, we show that migrating quail mesencephalic neural crest cells grafted into the trunk of host chick embryos colonise the sympathetic ganglia. While many express dHAND and form tyrosine hydroxylase (TH)-positive catecholaminergic neurons, the proportion that expresses either dHAND or TH is significantly smaller than that of quail trunk neural crest cells under the same conditions. Furthermore, the proportion of quail mesencephalic neural crest cells that is TH+ in the sympathetic ganglia decreases with time, while the proportion of TH+ quail trunk neural crest-derived cells increases. Thus, a subset of mesencephalic neural crest cells fails to express dHAND or TH in the sympathetic ganglia, while a further subset initiates but fails to maintain TH expression. Taken together, our results suggest that a subpopulation of migrating mesencephalic neural crest cells is refractory to catecholaminergic differentiation signals in the trunk. We suggest that this heterogeneity, together with local signals that repress catecholaminergic differentiation, may ensure that most ciliary neurons adopt a cholinergic fate.

Animals↗

PubMed2003

Short-duration fatigue alters neuromuscular coordination of trunk musculature: implications for injury.

The aim of this investigation was to determine the effect of muscle fatigue, produced by two different fatigue protocols, on the coordination of trunk and thigh muscles during the performance of a manual-handling task (e.g. a weighted stoop lift). The two fatigue protocols were designed to produce either (a) a non-specific widespread fatigue of trunk and limb muscles (e.g. rowing fatigue protocol), or (b) a specific fatigue of the trunk extensor musculature (e.g. back extension fatigue protocol). Specifically, we wished to determine whether the coordination of trunk muscles during a stoop lift was compromised more, or less, by either of these two fatigue protocols. Ten male subjects (20-24 years) were tested utilising an electromyographic technique which collected electromyograms from trunk flexor and extensor muscles, as well as the Hamstring muscle group, during a pre- and a post-fatigue performance of a weighted stoop lift. The results showed that the back extension fatigue protocol, but not the rowing fatigue protocol, produced significant (p<0.05) changes in the timing of trunk muscle activation during a stoop lift. The longer periods of muscle activation seen only after the back extension fatigue protocol, suggested that fatigue of these muscles had required the CNS to alter their periods of activation to a pattern similar to that previously seen in elderly populations. The results also suggested that intense short-duration motor tasks, which may differentially target the back and its musculature, could leave the spine susceptible to increased risk of injury even though worker perceptions of general fatigue are low. Risk assessment guidelines for manual handling should consider not only the weight and frequency of the lift, but lift duration as well to maintain worker safety.

Adult↗

PubMed1999

The influence of stance-phase knee flexion on the vertical displacement of the trunk during normal walking.

OBJECTIVE: To determine the effect of stance-phase knee flexion on the trunk's vertical displacement in normal walking. SUBJECTS: Three able-bodied adult male volunteers. DESIGN: Kinematic data describing the joint centers and joint angles of the legs and pelvis were collected from the subjects. The subjects walked at four target speeds (range, approximately 1.0 to 2.0 m/sec); a minimum of three trials of data at each walking speed were collected and processed. SETTING: Clinical gait analysis laboratory. RESULTS: Stance-phase knee flexion was not found to significantly reduce the peak-to-peak amplitude of the trunk's vertical displacement in normal walking. The reason for this has to do with the timing (ie, phase) of the stance-phase knee flexion wave with respect to the trunk's vertical displacement during the gait cycle. Stance-phase knee flexion in normal walking was found to reduce the mean elevation of the trunk by a few millimeters and to delay the trunk's vertical displacement waveform by about 2% to 6% of the gait cycle from where it would have been otherwise. CONCLUSIONS: Contrary to conventional wisdom, stance-phase knee flexion does not appreciably reduce the amount of vertical movement of the trunk in normal walking.

Adult↗

PubMed1997

Spine loading during trunk lateral bending motions.

Increases in lateral trunk velocities have been identified as a mechanism for increasing the risk of low-back disorder. Previous studies have identified an increase in coactivation of the trunk musculature during lateral bends, but no studies have evaluated how spine loading changes as lateral trunk velocity increases. Twelve subjects were asked to lift loads laterally at one static and three dynamic velocities. Ten trunk muscle activities and trunk kinematics were documented and used as input parameters to an EMG-assisted model to evaluate spine loading. Muscle coactivation was observed in all lateral bends. Coactivation significantly increased during dynamic trials compared to the static trials. Coactivity increased spinal loads by as much as 25% compared to values predicted by models that did not consider coactivity. Movements to the right significantly increased spine loadings (252 N increase in compression) compared to movements to the left. Spine compression, A-P shear, and lateral shear all increased in the dynamic trials compared to the static conditions. Peak compression increased by an average of 525 N at 45 degrees s-1 compared to static loading. Compression and lateral shear increased monotonically as trunk velocity increased. It is expected that this combined (compression and lateral shear) loading is the mechanism for increased risk observed in industry.

Adult↗

PubMed2000

Optimal sagittal motion axis for trunk extension and flexion tests in chronic low back trouble.

OBJECTIVE: To find the optimal height for sagittal motion axis for trunk strength test in chronic low back trouble. DESIGN: Cross-sectional study. BACKGROUND: The strength of trunk muscles of low back pain patients is decreased. The measured strength depends on the height of the sagittal motion axis but the differences between patients and controls are not known. METHODS: 114 (67 female) patients with chronic low back trouble are classified according to Quebec Task Force, 50 (31 female) patients with rheumatic disorder, but without low back trouble, and 33 (22 female) healthy controls, no appreciable physical differences but clear differences in Oswestry score. Isometric trunk extension-flexion test with different heights for the pelvic fulcrum. RESULTS: Force decreased in extension, increased in flexion, and torque increased both in flexion and extension in every group (P<0.001) as the fulcrum was moved caudally. The male controls were stronger than patients with low back trouble (P<0.01). The female controls were stronger only if the fulcrum was set at the hip joint level (P<0.05). There were no differences between patients with rheumatic disorder and low back trouble, except in extension if the fulcrum was at the hip joint level (P<0.02). CONCLUSIONS: The rotation axis in trunk extension-flexion strength test should be set at the level of the hip joint. RELEVANCE: Trunk muscle weakness is a common sign of different rheumatic disorders. Proper setting of sagittal motion axis and concomitant measurement of trunk and hip extensor or flexor muscles increases the specificity of the strength test for low back trouble.

Abdominal Muscles↗

PubMed2001

Comparative ability of EMG, optimization, and hybrid modelling approaches to predict trunk muscle forces and lumbar spine loading during dynamic sagittal plane lifting.

OBJECTIVE: To compare the ability of three modelling approaches to resolve the muscle and joint forces in a lumbar spine model during dynamic sagittal plane lifting. DESIGN: Trunk muscle forces, spine compression, and coactivity predicted through double linear optimization, EMG-assisted, and EMG assisted by optimization approaches were compared.Background. The advantages of EMG-based approaches are known from static task analyses. Limited assessment has been made for dynamic lifting. METHODS: Eleven male subjects performed sagittal plane lifting-lowering at fixed cadence from 0 degrees to 45 degrees of trunk flexion with and without an external load of 12 kg. Three-dimensional kinematics and dynamics as well as surface EMG provided inputs to a 12 muscle lumbar spine model. RESULTS: Trunk muscle coactivity was different between the modelling approaches but spine compression was not. Both EMG-based approaches were sensitive to trunk muscle coactivity and imbalance in left-right muscle forces during sagittal plane lifting. Overall, the best correlations between predicted forces and EMG as well as between forces predicted by different modelling approaches were obtained with the EMG-based models. Only the EMG assisted by optimization approach simultaneously satisfied mechanical and physiological validity. CONCLUSIONS: Both EMG-based approaches demonstrated their potential to detect individual trunk muscle strategies. A more detailed trunk anatomy representation would improve the EMG-assisted approach and reduce the adjustment to muscle force gain through EMG assisted by optimization. RELEVANCE: Injury to the lumbar spine could command alternative strategies of motion to attenuate pain and damage. To understand these strategies, the ideal lumbar spine model should predict individual muscle force patterns and satisfy mechanical equilibrium.

Adult↗

PubMed1997

Development and application of predictive equations of maximal static moments generated by the trunk musculature.

OBJECTIVE: To develop and apply regression equations that predict the maximal static moments generated by the extensor, axial rotator and lateral flexor muscles of the trunk as a function of forward bending angles and asymmetrical positions of the torso in human subjects. DESIGN: Using experimental data, polynomial predictive equations were developed. The equations were applied in an algorithm to estimate the maximal moment generated by individual subjects. METHODS: Three groups of male subjects participated in the evaluation of the effect of forward bending and trunk asymmetry on the static moment of the extensor, right axial rotator, and right lateral flexor muscles of the trunk, respectively. Two other groups of male subjects were evaluated to test the validity of the algorithm. During the dynamometric tests, the three-dimensional position of the trunk was determined using cinematography techniques. RESULTS: For the extensor muscles, a curvilinear increase of the maximal moment was observed with forward bending, with a slight decrease of the moment on each side of the neutral position. For the right axial rotator muscles, both forward bending and left asymmetrical position of the trunk increased the maximal moments generated by these muscles. The right lateral flexors were stronger in the standing and mid-flexion positions than in other positions. First-order, second-order and interaction terms appear in the regression equations to account for the effect of forward bending and asymmetrical positions. The regression equation for the extensors and right axial rotator muscles have R(2) coefficients (range 0.56-0.76) higher than those of the lateral flexor regression equations (range 0.09-0.12). The algorithm results in an average error of 13% in predicting the strength of extensor and axial rotator muscles of individual subjects. CONCLUSION: The results have shown that strength of the extensor and axial rotator muscles is affected by forward bending and the asymmetry of the trunk, while strength of the lateral flexor muscles is only dependent on the forward bending position. The regression equations and the corresponding algorithm are applicable for the range of positions used in the study.

Journal Article↗

PubMed1998

Myo-electric behavior of the trunk muscles during static load holding in healthy subjects and low back pain patients.

OBJECTIVE: The purposes of this study were to examine coactivational activities of four trunk muscles in various static holding tasks, and to examine the differences of muscle activation patterns between normal subjects and low back pain (LBP) patients. DESIGN: We used an one-way analysis of variance (anova) with repeated measures to analyze the effect of the knee angles, trunk flexion angles, and loading conditions on the amount of EMG activity. BACKGROUND: Epidemiologic studies attribute a considerable proportion of the incidence of LBP to lifting-related injuries. The relationship between LBP and trunk muscles integrated electromyography (IEMG) is controversial. METHODS: Forty volunteer subjects with no experience of LBP and 47 LBP patients recruited from Chung-Gung Memory Hospital participated in this experiment. Surface IEMG signals of four right and left trunk muscles (rectus abdominis, external oblique, erector spinae, and latissimus dorsi) were obtained in static holding tasks. RESULTS: In knee flexion, LBP patients had significant IEMG pattern change than normal subjects. In trunk flexion and loading conditions, normal subjects had significant IEMG pattern change than LBP patients. CONCLUSIONS: Trunk muscle groups have different muscle coactivation patterns in functional posture of load holding. Using surface EMG can discriminate LBP patients from normal subjects.

Journal Article↗

PubMed2000

Surgical repair of the pulmonary trunk aneurysm.

OBJECTIVE: Aneurysm formation of the pulmonary trunk is rare and there is controversy about optimal treatment for this disease. The aim of this article is to report four patients with pulmonary trunk aneurysm which were managed by surgical repair. MATERIALS AND METHODS: From 1986 to 1997, we performed surgical repair for pulmonary trunk aneurysm in four patients. There was one male and three female patients with a mean age of 63.3 years (range: 54-78 years). Concomitant diseases were cardiac valvular disease in four patients, thoracic aortic dissection in two, atherosclerotic abdominal aortic aneurysm in two, and coronary artery disease in one. All patients were in New York Heart Association functional class III preoperatively. Surgical procedures for the pulmonary trunk aneurysm included Dacron graft replacement in two patients and aneurysmorrhaphy in two. Associated procedures were cardiac valvular operation in three patients with four lesions and right ventricular outflow tract reconstruction (RVOTR) in one. RESULTS: There were no operative mortalities and no late deaths with a mean follow-up period of 6.6 years (range: 2.4-10.0 years). One female patient developed recurrent pulmonary trunk aneurysm 9.5 years after aneurysmorrhaphy, and underwent a second operation where Dacron graft replacement of the aneurysm including pulmonary valve replacement was performed successfully. All patients are now leading normal lives. CONCLUSIONS: Surgical management should be considered for large aneurysm of the pulmonary trunk regardless of its etiology and underlying disease to prevent possible rupture with fatal result if the patient has an acceptably low operative risk.

Aged↗

PubMed1999

Tunicate tails, stolons, and the origin of the vertebrate trunk.

Tunicates are primitive chordates that develop a transient 'tail' in the larval stage that is generally interpreted as a rudimentary version of the vertebrate trunk. Not all tunicates have tails, however. The groups that lack them, salps and pyrosomes, instead have a trunk-like reproductive stolon located approximately where the tail would otherwise be. In salps, files of blastozooids are formed along the sides of the stolon. The tail and caudal trunk in more advanced chordates could have evolved from a stolon of this type, an idea referred to here as the 'stolon hypothesis'. This means the vertebrate body could be a composite structure, since there is the potential for each somite to incorporate elements originally derived from a complete functional zooid. If indeed this has occurred, it should be reflected in some fashion in gene expression patterns in the vertebrate trunk. Selected morphological and molecular data are reviewed to show that they provide some circumstantial support for the stolon hypothesis. The case would be stronger if it could be demonstrated that salps and/or pyrosomes are ancestral to other tunicates. The molecular phylogenies so far available generally support the idea of a pelagic ancestor, but offer only limited guidance as to which of the surviving pelagic groups most closely resembles it. The principal testable prediction of the stolon hypothesis is that head structures (or their homologues) should be duplicated in series in the trunk in advanced chordates, and vice versa, i.e. trunk structures should occur in the head. The distribution of both rhabdomeric photoreceptors and nephridia in amphioxus conform with this prediction. Equally striking is the involvement of the Pax2 gene in the development of both the inner ear and nephric ducts in vertebrates. The stolon hypothesis would explain this as a consequence of the common origin of otic capsules and excretory ducts from atrial rudiments: from the paired rudiments of the parent oozooid in the case of the otic capsule (these express Pax2 according to recent ascidian data), and from tubular rudiments in the stolon in the case of the excretory ducts.

Animals↗

PubMed1999

Banding of the pulmonary trunk in preparation for a Fontan operation.

Banding of the pulmonary trunk is an important surgical procedure for patients who have congenital cardiac malformations with unrestricted pulmonary flow. We propose a new concept for determining in such circumstances the most appropriate length of the band used to constrict the pulmonary trunk in preparation for a Fontan operation. We studied 14 patients undergoing banding of the pulmonary trunk and measured the following parameters: diameter of aorta, diameter of pulmonary trunk, length of pulmonary arterial band and maximum flow velocity across the banded segment. We calculated an index from our original parameter based on the formula; length of band/(diameter of aorta diameter of pulmonary trunk). The diameter of aorta was 9.5 +/- 1.4 mm, and that of the pulmonary trunk was 9.6 +/- 2.3 mm. The length of the band was 16.5 +/- 3.4 mm, giving a calculated index of 0.188 +/- 0.038. The maximum flow velocity was 4.02 +/- 0.46 m/s. No correlation was found between the length of the band and body weight, and also no correlation was found between the length of the band and maximum flow velocity. The calculated index had a negative correlation with the maximum velocity of flow across the band (y = -8.13x +/- 5.56, R = 0.74, p < 0.01). We believe that the proposed index is a useful guide in determining the length of a pulmonary band when preparing patients for a Fontan operation.

Cardiac Catheterization↗

PubMed1992

The role of the diaphragm in trunk extension in tetraplegia.

Interest has been focused on the diaphragm as the all important respiratory muscle in tetraplegia for decades but its unique role as a trunk extension muscle has not been considered. This study set out to establish the relationship, if any, between the roles of the diaphragm during arm exercise and trunk flexion. Eight male complete cervical cord injuries (CCI) patients, sitting in their wheelchairs, were studied during rest, trunk flexion and start of arm cranking. The average flow, volume, oesophageal and gastric pressures (Poes and Pga) and the myoelectric activity of the diaphragm (EMGdi) were recorded. The EMGdi pattern changed from phasic activity at rest to continuous or almost continuous activity during trunk flexion. Patients were then either spontaneously holding their breath or breathing irregularly with rapid or shallow breaths. Also, the normalised EMGdi signal strength increased by an average of 150% and the mean Pga by about 3 kPa, while mean Poes decreased by about 0.5 kPa. At the start of exercise, patients with poor triceps function, less than MRC grade 3, exhibited similar ventilatory and EMGdi changes as had been seen in trunk flexion. In patients with better triceps function, only minor changes in these variables were observed. The findings suggest that the diaphragm acts both as a trunk extensor muscle and a respiratory muscle. During posture imbalance, the postural needs temporarily override the respiratory needs.

Adult↗