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At least 829 records · Page 46Linked to original sources

PubMed2000

Muscle activation in therapeutic exercises to improve trunk stability.

OBJECTIVE: To evaluate the relative activation amplitudes from 3 abdominal and 2 trunk extensor muscle sites in healthy subjects performing the pelvic tilt, abdominal hollowing, and level 1 of the trunk stability test (TST level 1) exercises and to compare the activation amplitudes among muscle sites and exercises. DESIGN: Prospective comparative study. SETTING: Motion Analysis Research Center, Dalhousie University, Canada. PARTICIPANTS: Twenty-four healthy men (mean age, 30 +/- 8.1 yr [SD]) without low back pain. INTERVENTIONS: Subjects performed 3 exercises in a balanced order, repeating each exercise 5 times while surface electromyography (EMG) was recorded from the 5 muscle sites. Exercises were divided into 2 phases: movement and stabilization. The root-mean-square amplitude of the EMG for each phase was calculated and normalized to the maximal voluntary isometric contraction (MVIC) amplitude for each muscle. A 2-factor repeated-measures analysis of variance (ANOVA) tested the muscle by exercise interaction and the main effects for each phase separately. MAIN OUTCOME MEASURES: Normalized activation amplitude was the main dependent variable. Ensemble-average curves were calculated to examine the phasing of activation. RESULTS: ANOVA showed a statistically significant interaction (p < .05) for both phases, indicating the 3 exercises recruited the 5 muscle sites using different patterns of relative activation. The external oblique (EO) muscle site was activated to higher amplitudes than the other 4 sites in all 3 exercises for both phases. The highest activity was recorded from the EO during the pelvic tilt, just more than 25% of MVIC. The only exercise to recruit the erector spinae to significantly higher amplitudes than the multifidus site was the TST level 1. CONCLUSIONS: Study exercises were not interchangeable for the patterns of trunk muscle activation amplitudes. The exercises did not recruit the abdominal muscles to adequate levels for strengthening for this healthy sample; however, all 5 muscle sites were activated, forming the basis of a stabilizing exercise approach.

Abdominal Muscles↗

PubMed2001

Electromyographic activity of selected trunk muscles during dynamic spine stabilization exercises.

OBJECTIVES: To compare the electromyographic activity of the trunk flexors and extensors during 2 spine stabilization exercises and to evaluate the changes in muscle activity with increasing levels of exercise difficulty. DESIGN: Descriptive study. SETTING: Research laboratory. PARTICIPANTS: Twelve healthy subjects without history of lower back pain. INTERVENTION: Subjects were instructed how to perform the Dying Bug and the Quadruped exercises. Electromyographic and motion data were recorded from each muscle group during maximum voluntary isometric contraction (MVIC). MAIN OUTCOME MEASURES: Surface electromyographic recordings of the erector spinae, rectus abdominus, abdominal oblique, and gluteus maximus muscles. RESULTS: During the Dying Bug exercise, the trunk flexors (rectus abdominus, abdominal oblique) were equally active and demonstrated proportional increases in electromyographic activity with increasing level of exercise difficulty. In the Quadruped exercise, significantly greater electromyographic activity was observed in the abdominal oblique compared with the rectus abdominus; however, abdominal oblique activity did not change with increasing level of difficulty. The erector spinae and gluteus maximus demonstrated a significant level effect and were most active during elevation of the ipsilateral leg. At no point did activity of any of the muscles studied exceed 41% of the MVIC. CONCLUSIONS: Results indicated the Dying Bug exercise predominantly recruited the abdominal musculature, while greater activity was observed in the trunk and hip extensors during the Quadruped exercise. The relatively low levels of electromyographic activity observed in both exercises suggests that the intensity of muscle recruitment is not likely sufficient to provide a strengthening effect in healthy subjects.

Abdominal Muscles↗

PubMed2002

Electromyographic activity of the lumbar and hip extensors during dynamic trunk extension exercise.

OBJECTIVE: To evaluate the effects of exercise intensity and multiple sets on muscle activation patterns during trunk extension exercise. DESIGN: Descriptive, repeated measures. SETTING: University-based musculoskeletal research laboratory. PARTICIPANTS: Twenty volunteers recruited from a university setting. INTERVENTION: Not applicable. MAIN OUTCOME MEASURES: Electromyographic activity was recorded from the L3-4 paraspinal region, gluteus maximus, and biceps femoris muscles during multiple sets of trunk extension exercise at intensities representing 40%, 50%, and 70% of peak isometric force. RESULTS: As exercise intensity increased, the electromyographic activity of the gluteus maximus increased to a greater extent than the activity of the paraspinal region. At the 50% intensity level, biceps femoris electromyographic activity was significantly greater than the paraspinal region electromyographic activity, whereas at the 70% intensity no differences were found between muscles. During multiple sets of exercise at the same intensity a muscle by set interaction was observed. This interaction revealed that with respect to other muscle groups, the electromyographic activity of the gluteus maximus increased between sets 1 and 2, whereas electromyographic decrements occurred in the paraspinal region. During exercise at the 40% intensity level, biceps femoris electromyographic activity increased to a greater extent between sets 1 and 2 when compared with the paraspinal region. CONCLUSION: Exercise intensity and multiple sets result in alterations in muscle recruitment patterns of the lumbar and hip extensor muscles. These findings raise questions as to the efficacy of added loading and multiple sets during trunk extension exercise.

Adult↗

PubMed2005

[Celiac trunk compression: angiographic phenomenon or cause of ischemic abdominal complaints?].

Compression of the celiac trunk commonly occurs in young men and women as well. Most of the patients suffering from this rare disease derive from a large pool of people having diffuse and chronic abdominal complaints including epigastric pain, postprandial abdominal pain and diarrhea leading to weight loss. Aim of the study was the finding of true criteria which can guarantee a successful operative procedure. A major issue in preoperative assessment is color flow Duplex imaging of the celiac axis. The most important finding aside from clinical symptoms is a peak flow in the celiac axis of more than 200 cm/s during inspiration and expiration position of the diaphragm. In addition arteriography of the celiac axis and superior mesenteric artery (SMA) showing a steal phenomenon is essential. Because of the rareness of the disease "only" 15 patients were operated on including intraoperative balloon dilatation of the celiac trunk. 93 % had a long term follow up success. Normal values of peak flow velocity in the mesenteric arteries were determined in more than one hundred healthy persons and compared to findings in the literature which were nearly identical. As a result of the study it could be shown that a successful outcome of the operative procedure can be expected when certain essential criteria are observed: 1. peak flow velocity in the celiac trunk higher than 200 cm/s during in- and expiration 2. steal effect via pancreatic arcades from the superior mesenteric artery documented by Duplex ultrasound and arteriography 3. triad of symptoms: epigastric pain, postprandial pain and weight loss of more than 5 kg. Special emphasis is given to the possible occurrence of severe complications after liver transplantations and pancreatic surgery, if the diagnosis "median arcuate ligament compression" is not known.

Abdomen, Acute↗

PubMed2005

Effects of low back disability status on lower back discomfort during sustained and cyclical trunk flexion.

A laboratory study was conducted to determine the effects of back disability status on endurance time and perceived discomfort during trunk flexion. Eighty participants (40 with chronic or recurrent low back pain (CRLBP), 40 pain-free) were tested. The trunk was flexed to 15 degrees, 30 degrees, 45 degrees and 60 degrees under three conditions: 1) continuous static flexion; 2) cyclical flexion with 20% rest; and 3) cyclical flexion with 40% rest. Each condition was performed for up to 600 s or until the participant reached his/her pain tolerance limit. Dependent variables included time to distracting discomfort (TDD), total endurance time (TET) and perceived discomfort. For continuous exertions, CRLBP participants had lower TDD (p < 0.001), lower TET (p < 0.001) and greater discomfort (p < 0.001) compared to pain-free controls. In both groups, TDD and TET decreased and perceived discomfort increased as the flexion angle increased. For intermittent exertions, CRLBP participants reported greater discomfort than pain-free participants (p < 0.001). Increasing rest from 20 to 40% reduced discomfort in CRLBP participants, but produced no consistent benefit in pain-free participants. To accommodate persons with CRLBP, consideration should be given to reducing both the magnitude (angle) and duration of trunk flexion required by their jobs.

Adult↗

PubMed1995

Effects of posture, weight and frequency on trunk muscular activity and fatigue during repetitive lifting tasks.

We examined the effects of posture, weight and frequency on trunk muscular activity and fatigue during repetitive dynamic lifting. Electromyographic (EMG) signals from eight primary trunk muscles were collected during 120 min for four different task conditions. The patterns of muscle recruitment and the levels of relative activation were analysed using the normalized EMG data. Median power frequency (MPF) shift patterns were analysed to examine muscular fatigue. The muscles in the dorsal part of the trunk were activated at the symmetric posture, while the muscles on the contralateral side to the workload were more strongly activated at the asymmetric posture. Decreasing trends of MPFs were found in some active muscles, and they were more pronounced for the asymmetric posture than for the symmetric posture. It was also seen that the muscles became fatigued faster for the light load-high frequency task than for the heavy load-low frequency task.

Abdomen↗

PubMed1998

Stability and Control of Human Trunk Movement During Walking.

A mathematical model has been developed to study the control mechanisms of human trunk movement during walking. The trunk is modeled as a base-excited inverted pendulum with two-degrees of rotational freedom. The base point, corresponding to the bony landmark of the sacrum, can move in three-dimensional space in a general way. Since the stability of upright posture is essential for human walking, a controller has been designed such that the stability of the pendulum about the upright position is guaranteed. The control laws are developed based on Lyapunov's stability theory and include feedforward and linear feedback components. It is found that the feedforward component plays a critical role in keeping postural stability, and the linear feedback component, (resulting from viscoelastic function of the musculoskeletal system) can effectively duplicate the pattern of trunk movement. The mathematical model is validated by comparing the simulation results with those based on gait measurements performed in the Biomechanics Laboratory at the University of Manitoba.

Journal Article↗

PubMed1994

The effect of trunk angle on power production in cycling.

The purpose of this investigation was to determine the effect of three different trunk angles (60, 90, and 120 degrees relative to the ground) on power production of 16 male recreational cyclists (age 20-36 years) when the hip, knee, and ankle angles were controlled. Wingate anaerobic tests were performed on a modified Monark cycle ergometer against a resistance of 85 g/kg of the subjects' body mass (5.0 J/crank rev/kg BM). The order of test conditions was randomly assigned, with a minimum of 24 hr between sessions. A DM MANOVA and post-hoc tests revealed that peak power at the 60 and 90 degree trunk angle was significantly greater than that at the 120 degree angle, and mean power in the 90 degree angle was significantly greater than that at the 120 degree angle. It was concluded that changes in cycling trunk angle may affect peak power and mean power.

Adult↗

PubMed1975

Premature pubarche and the growth of the trunk in paralysed children.

In a hospital supervising prolonged orthopaedic treatment of children suffering from neurological affections, isolated premature pubarche appeared very frequently in children suffering from severe paralytic sequelae of acute anterior poliomyelitis. These subjects had a greater progression of scoliosis and segmental disproportion than comparable subjects of the same age. Supine length and crown-rump length were studied during growth in 16 paralysed boys and 22 paralysed girls with premature pubarche. The results were compared with those of two control populations, one normal group (274 girls, 246 boys), the other a paralysed group (49 boys and 38 girls). Paralysed children (group with premature pubarche and control group) all show considerable shortening of the legs. Up to age 11 for girls and 13 for boys, children with premature pubarche had longer trunks than normal, while supine length was normal. Premature slowing of growth then occurred, bringing the trunk to normal values and supine length to very low values for age. This is ascribed to premature pubertal growth of the trunk. The roles of hormonal changes and neurological damage are discussed.

Body Height↗

PubMed2005

Discriminant ability of the Trunk Impairment Scale: A comparison between stroke patients and healthy individuals.

PURPOSE: The Trunk Impairment Scale (TIS) is a standardized scale to evaluate the trunk function in stroke patients. It was the aim of this study to determine the discriminant ability of the TIS by comparing stroke patients with healthy individuals. Further, the variables that had an influence on obtaining a high score on the TIS in healthy subjects were examined. METHOD: Forty stroke patients and 40 age- and sex-matched healthy individuals were included in the study. TIS scores from the stroke patients and healthy individuals were compared using the Wilcoxon ranked sum test. RESULTS: Sub-scale and total TIS scores showed significant differences between stroke patients and healthy individuals (P < 0.0001). Univariate analysis and logistic regression analysis further revealed that younger persons, women and people who are more active in daily life have a higher chance of obtaining a high score on the TIS. CONCLUSIONS: The TIS discriminates between stroke patients and healthy individuals. A submaximal score on the TIS was found in 45% of the healthy subjects suggesting that a lower score on the TIS still indicates normal trunk function and full participation in daily life.

Abdomen↗

PubMed1993

Three dimensional visualisation of velocity profiles in the normal porcine pulmonary trunk.

OBJECTIVE: The aim was to obtain detailed data of velocity profile development in the porcine pulmonary trunk. METHODS: Hot film anemometry was used for point blood velocity measurements in the entire cross sectional area one diameter downstream of the normal porcine pulmonary valve. Computerised three dimensional visualisations of the spatial and temporal development of blood velocity profiles were made. Measurement series were conducted under spontaneous and stressed haemodynamic conditions in 16 pigs with a body weight of approximately 90 kg. RESULTS: The velocity profiles revealed consistent temporal and spatial development characteristics. In the systolic acceleration phase the profile was flat, but during peak systole an initially counterclockwise rotation was seen; subsequently the profile turned clockwise and ultimately counterclockwise to become flat during early and late systolic deceleration phases. CONCLUSIONS: These skewed, rotating velocity profiles are in conflict with the generally accepted assumption that the velocity profile in the pulmonary trunk is flat. The rotating skewness of the velocity profile in the porcine pulmonary trunk has not been described before. The reason for the rotating velocity profile is obscure.

Animals↗

PubMed1996

Occurrence of larval Ixodes scapularis (Acari:Ixodidae) on tree trunks.

Host-seeking larvae of blacklegged ticks, Ixodes scapularis Say, were found on the trunks of 7 species of trees in a mixed deciduous woodland in Maryland. Where larvae were present around the bases of trees, larvae were found on 45.8% of the tree trucks. Almost 15% of the larvae found on tree trunks were approximately 1-2 m above the ground. Larger trees harbored larvae more often than smaller trees. Trees having a circumference at breast height of > or = 1 m (0.96 m diameter) averaged 3.19 larvae. Because white-footed mice, Peromyscus leucopus (Rafinesque), the principal hosts of I. scapularis larvae, frequently nest in trees, it may not be detrimental to host-seeking larvae to ascend and remain on tree trunks.

Animals↗

PubMed2007

Geophysical imaging of root-zone, trunk, and moisture heterogeneity.

The most significant biotic and abiotic stress agents of water extremity, salinity, and infection lead to wood decay and modifications of moisture and ion content, and density. This strongly influences the (di-)electrical and mechanical properties and justifies the application of geophysical imaging techniques. These are less invasive and have high resolution in contrast to classical methods of destructive, single-point measurements for inspecting stresses in trees and soils. This review presents some in situ and in vivo applications of electric, radar, and seismic methods for studying water status and movement in soils, roots, and tree trunks. The electrical properties of a root-zone are a consequence of their moisture content. Electrical imaging discriminates resistive, woody roots from conductive, soft roots. Both types are recognized by low radar velocities and high attenuation. Single roots can generate diffraction hyperbolas in radargrams. Pedophysical relationships of water content to electrical resistivity and radar velocity are established by diverse infiltration experiments in the field, laboratory, and in the full-scale 'GeoModel' at Kiel University. Subsurface moisture distributions are derived from geophysical attribute models. The ring electrode technique around trunks images the growth ring structure of concentric resistivity, which is inversely proportional to the fluid content. Healthy trees show a central high resistivity within the dry heartwood that strongly decreases towards the peripheral wet sapwood. Observed structural deviations are caused by infection, decay, shooting, or predominant light and/or wind directions. Seismic trunk tomography also differentiates between decayed and healthy woods.

Electric Impedance↗

PubMed1985

Quantitative measure of cutaneous sensation. Two-point discrimination values for the face and trunk.

This study was performed to assess two-point discrimination ability for skin areas of the face and trunk. Using a compass-type instrument, I determined two-point discrimination values for three areas on the face and eight, nonoverlapping regions of the neck and trunk in a sample of 43 healthy young adult men and women. Mean values for the face ranged from 14.9 mm over the eyebrow to 10.4 mm along the lateral aspect of the mandible. Values for the neck and trunk ranged from 35.2 mm for skin of the lateral neck to 55.4 mm for the region immediately lateral to the C7 spinous process. I also found interindividual variation in two-point discrimination ability for a given skin area. Except for skin overlying the body of the mandible, where values for women were lower than those measured in men, no significant differences in discrimination ability were found between men and women. Although assessment of two-point discrimination is useful in the clinical evaluation of certain types of patients, the existence of intraindividual and interindividual differences suggests that therapists must interpret the results of these tests with caution.

Adolescent↗

PubMed1987

Comparison of the effectiveness of two pelvic stabilization systems on pelvic movement during maximal isometric trunk extension and flexion muscle contractions.

The purpose of this study was to compare the effectiveness of two pelvic fixation systems to limit pelvic movement during isometric trunk extension and flexion muscle strength testing. We developed a prototypal pelvic fixation system and compared it with a pelvic strap stabilization system. The prototypal pelvic fixation system consisted of fixation of the anterior superior iliac spines and sacrum, and the pelvic strap stabilization system consisted of a strap across the anterior superior iliac spines and a posterior pad. Small, but statistically significant, pelvic position changes occurred during isometric trunk extension and flexion muscle strength testing with the two stabilization systems. The pelvic angle changes were greater in extension than in flexion and greater when only the pelvic strap stabilization system rather than the prototypal pelvic fixation system was used. Our findings indicate that a more extensive prototypal pelvic fixation system minimizes pelvic movement to a greater extent during isometric trunk extension and flexion muscle contractions compared with the strap stabilization system.

Abdominal Muscles↗

PubMed1989

Peak torque-to-body weight ratios in the trunk: a critical analysis.

The purpose of this study was to document the relationships between body weight and isokinetic extension and flexion peak torque produced by the trunk musculature. Using a dynamometer, we collected isokinetic measurements during trunk flexion and extension at speeds of 60 degrees and 120 degrees/sec on 61 healthy subjects (29 men, 32 women; 20-60 years old) while standing. Extension and flexion peak torque measurements were calculated for each subject at each speed. Male and female subjects' data were analyzed separately. Each subject's body weight was paired with peak torque at each speed, and Pearson product-moment correlation coefficients (r) were calculated. The correlation coefficients ranged from .27 to .39 for extension and from .66 to .70 for flexion, establishing a positive linear relationship between body weight and each of the isokinetic measurements. Body weight accounted for very small proportions of the variance (as low as 7%-15% in extension isokinetic measurements). In attempting to use a client's body weight to predict isokinetic peak torque measurements, the clinician should be aware that a great deal of unaccounted for variance exists. We recommend that clinicians use other variables (eg, activity level, age) in addition to body weight to control for individual differences among healthy subjects when measuring isokinetic trunk extension muscle performance.

Adult↗

PubMed1997

Electromyographic amplitude and frequency changes in the iliocostalis lumborum and multifidus muscles during a trunk holding test.

BACKGROUND AND PURPOSE: Muscle endurance is an important variable to measure in the assessment of back muscle function. This study investigated the electromyographic (EMG) activity and fatigue patterns of iliocostalis lumborum and multifidus muscles during a trunk holding test. SUBJECTS: Sixteen male subjects (mean age = 24.2 years, SD = 4.2, range = 20.6-31.9) without low back pain or known pathology were recruited in the study. METHODS: Surface EMG electrodes were used to record the activity of iliocostalis lumborum and mutifidus muscles during a 60-second isometric contraction. To reflect the activity level and fatigue rate of the muscles. EMG amplitude (root mean square [RMS] values) and a frequency variable (median frequency [MF]) were measured. RESULTS: The multifidus muscle displayed a higher level of activity, initial MF, and normalized MF slope than did the iliocostalis lumborum muscle. There was no difference, however, in the normalized RMS slope between the two muscles. The correlations between the normalized MF slope and the RMS slope of the two muscles were nonsignificant. CONCLUSION AND DISCUSSION: This study shows that monitoring frequency changes of the EMG signals may enable therapists to quantify the fatigue changes of individual muscles during the trunk holding test. The higher fatigue rate shown in the multifidus muscle compared with the iliocostalis lumborum muscle may be due to the higher activity level of the multifidus muscle during te trunk holding contraction. This greater activity of the multifidus muscle during the contraction might be explained by the functional differences between these two muscles.

Adult↗

PubMed2006

Usefulness of diurnal trunk shrinkage as a water stress indicator in plum trees.

We compared seasonal changes in maximum diurnal trunk shrinkage (MDS) with seasonal changes in midday stem water potential (Psi(s)) over three years in plum trees grown in differing drip-irrigated regimes. In well-irrigated trees, day-to-day variations in Psi(s) and MDS were related to evaporative demand. Reference equations were obtained to predict MDS and Psi(s) values for well-irrigated trees as functions of environmental conditions. A decrease in plant water status toward the end of the growing season occurred even in the well-irrigated trees, probably reflecting a reduced volume of soil wetted by the drip irrigation system. Thus, for the prediction of Psi(s), different reference equations are required for the fruit-growth and after-harvest phenological periods. A seasonal change in the relationship between MDS and Psi(s) was observed, which compensated for the decrease in plant water status such that well-irrigated trees had similar MDS values during both the fruit-growth and after-harvest periods. The influence of tree size on the relationship between MDS and Psi(s) was also investigated. For tree trunk diameters ranging between 8 and 13 cm, MDS increased 13% for each cm of increase in trunk diameter, as a result of the thicker phloem tissues of the larger trees. This finding may allow extrapolation of Psi(s) predictions based on empirical relationships with MDS to plum trees of different sizes.

Circadian Rhythm↗