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At least 847 records · Page 47Linked to original sources

PubMed2007

Crop load affects maximum daily trunk shrinkage of plum trees.

We studied the effects of low fruit load (3-4 fruits cm(-2) of trunk cross-sectional area (TCSA), and high fruit load (6-7 fruits cm(-2) TCSA) on maximum daily trunk shrinkage (MDS) and trunk growth rates (TGR) over two seasons in plum (Prunus salicina Lindell) trees receiving full irrigation or deficit irrigation. Seasonal changes in MDS and TGR were compared with those in midday stem water potential (Psi(s)) and leaf stomatal conductance (g (s)). Crop load increased g (s) in fully irrigated trees approaching harvest. Although crop load did not affect plant water status in either watering regime, there were considerable differences in both MDS and TGR as a function of crop load. Compared with low-cropping [corrected] trees, MDS was 34% higher and TGR was 48% lower in high-cropping [corrected] trees. The differential responses of MDS and Psi(s) to crop load were a consequence of a higher MDS for a given Psi(s) in the high-cropping trees compared with the low-cropping trees. There was a linear increase in MDS with crop load, with a slope of 15.2 microm MPa(-1) per unit increment of crop load. In the fully irrigated trees, day-to-day variations in MDS were related to evaporative demand; however, the slope of the relationship between MDS and evaporative demand increased with crop load, indicating that different reference equations must be used to adjust for tree crop load when using MDS to determine plant water status and irrigation requirements.

Fruit↗

PubMed1995

Trunk and head stabilization during the first months of independent walking.

This study measured the rate of acquisition of head and trunk postural control during the two early developmental periods of independent walking, as defined by global gait parameters. Gait parameters were observed longitudinally in four children. The maximum angular deviations of the trunk and head oscillations were computed in the frontal and sagittal planes. These decreased most dramatically during the first 10-15 weeks of independent walking, during the same period when global gait parameters changed rapidly. This head and trunk stabilization may be a fundamental process that help to maintain equilibrium during walking, and may be a necessary step prior to the development of fine posturo-motor control.

Analysis of Variance↗

PubMed2001

Effects of eccentric exercise on trunk extensor torque and lumbar paraspinal EMG.

PURPOSE: Little is known about the effects of eccentric contractions on the function of the lumbar paraspinal muscles. The purpose of this study was to determine the effects of a single bout of eccentric contractions using the trunk extensor muscles on torque and lumbar paraspinal electromyographic (EMG) parameters. METHODS: Twenty healthy men between the ages of 18 and 49 yr participated in the study. Subjects performed a single bout of 50 maximal voluntary concentric (N = 10) or eccentric (N = 10) trunk extension movements while surface EMG signals were recorded from the multifidus and iliocostalis lumborum muscles. A series of isometric contractions were performed both before the exercise protocol and at five additional time points over the following 7 d. RESULTS: During the exercise protocol, peak torque decreased 30% and 24% in the eccentric and concentric groups, respectively, whereas no change occurred in EMG root-mean-square (RMS). There were no group differences in peak torque generation at any of the postexercise protocol time points. Compared with the preexercise protocol values, multifidus EMG was elevated 27% immediately post and 15 min post in the eccentric group. Similarly, compared with the concentric group, multifidus EMG in the eccentric group was increased 34%, 40%, and 25% immediately post, 15 min post, and 1 d after the exercise protocol, respectively. CONCLUSION: Eccentric contractions using the trunk extensor muscles result in higher levels of multifidus EMG activity to produce a given level of torque. This reduction in neuromuscular efficiency persisted for one day with recovery to baseline levels by the third day. Contrary to studies using other muscle groups, no sustained alteration in muscle function was observed.

Adolescent↗

PubMed2002

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

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

Abdominal Muscles↗

PubMedDate not supplied

Trunk strengths in attempted flexion, extension, and lateral bending in healthy subjects and patients with low-back disorders.

Trunk strengths were measured in 27 health males and 30 health females, and in 25 male and 15 female patients with low-back pain and/or sciatica. Maximum voluntary isometric strengths were measured during attempted flexion, extension, and lateral bending from an upright standing position. Both male and female patients had approximately 60% of the absolute trunk strengths of the corresponding healthy subjects. Intra-individual trunk strength ratios were used to interpret the results. Use of these ratios tends to avoid interpretational problems created by the general weakness of the patients and any lack of motivation of either patients or healthy subjects. The ratios showed that the patients had attempted extension strengths that were significantly less than their strengths in the other types of movements tested. The strength ratios for attempted extension were particularly low for patients with sciatica.

Adult↗

PubMed1984

Prevalence study of trunk asymmetries and structural scoliosis in 10-year-old school children.

The prevalence of trunk asymmetries was studied in 6464, 10-year-old, school children in Malmö City. All those with visible trunk asymmetries were moiré photographed and a subset roentgenographed. Moiré, positive findings were seen in 13% of the boys and in 16% of the girls. A more prominent moiré asymmetry (a deviation of two moire contour lines or more) was seen in 0.6% of the boys and 0.9% of the girls. The Cobb angles in this latter group varied between 14-25 degrees. Children with small clinical and moiré asymmetries (deviations of less than one moiré fringe) had no or very small (less than 10 degrees), lateral deviations seen on the x-ray and should, therefore, be regarded rather as normal variations of the shape of the trunk. On the other hand, these small asymmetries cannot be disregarded as possible indications of a risk group in which structural scoliosis can develop later during the period of growth.

Braces↗

PubMed1984

Posture related to myoelectric silence of erectores spinae during trunk flexion.

Electromyographic activity of erectores spinae exhibits points of abrupt change during trunk flexion from the erect position and return extension. This study examined the positions at which the myoelectric activity suddenly disappeared and later reappeared. Forty adults were investigated to define accurately the inclinations of the trunk, pelvis, and vertebral column at these positions. The positions at the commencement and cessation of the period of electrical silence both occurred at two-thirds of maximum trunk flexion (mean = 80 degrees +/- 13 degrees SD). At these positions, all flexion measurements were significantly less than their maxima (P less than 0.001). Hip flexion at the commencement of electrical silence was slightly above one-half its maximum range, and similar to the position at the recommencement of electrical activity (mean = 40 degrees +/- 12 degrees SD). The most reproducible measurement (r = 0.88) in both positions was vertebral flexion (89% Max.; mean = 48 degrees +/- 6 degrees SD). Eleven of the male subjects repeated the experimental task holding 10.1 kg in their hands. The effect of this was to produce inhibition and reactivation of erectores spinae at a greater degree of vertebral flexion.

Adolescent↗

PubMed1986

The bending stiffness of the trunk.

Much research is done on the physical properties of the isolated human spine. However, little knowledge exists about the relationship between the physical properties of an isolated spine and the physical properties of the whole trunk in vivo. The first part of this article is a literature review. The next part is a description of experiments performed to study the bending stiffness in flexion of the whole trunk in vivo. One hundred fifty measurements were made in unanesthetized subjects and 150 in anesthesized ones. The bending stiffness of the whole trunk in vivo was found to be about 10 times larger the mean bending stiffness of an isolated spine.

Adult↗

PubMed1987

Comparison of clinical and objective methods of assessing trunk muscle strength--an experimental approach.

An objective method was used to evaluate the validity of the sit-up, prone trunk extension, and double leg lowering clinical tests. Normal men and women and patients with a history of backache served as subjects. The vast majority of the subjects were able to perform the Grade 1 level, which was the highest resistance imposed by the sit-up and prone extension tests. The double leg lower was superior to the other two clinical tests but was able to identify only broad differences in strength capability. In the main, the subjective clinical tests were poor discriminators and seemed to lack the range of resistance necessary to be definitively useful as methods of assessing trunk muscle strength and may not provide appropriate resistance for improving trunk muscle strength in most patients.

Adult↗

PubMed1987

The activity of individual trunk muscles during heavy physical loading.

The myoelectric activity of ten trunk muscles were recorded, using intramuscular electrodes, when ten subjects made maximal and 50% of maximal static exertions in standing postures. Exertions were made in flexion, extension, and left and right lateral bending. Three heavy-lifting tasks also were studied. A biomechanical model was used to predict the forces in the trunk muscles, and the predictions then were compared to the measurements. The abdominal muscles were all active in attempted flexion, while the erector spinae muscles were inactive. In attempted extension, the erectors were maximally active, but considerable activity was present in the abdominal muscles as well. The highest activity levels recorded in the oblique abdominal muscles were in lateral bending. There were high degrees of correlation between the measured muscle activities and predicted muscle tensions for the erector spinae and rectus abdominus muscles, while the correlation coefficients for the oblique abdominal muscles were lower (0.4-0.7). The study indicates that inclusion of antagonistic activity is an important consideration to improve model predictions. The oblique abdominal muscles appear to be more active, in general, than predicted. For the longitudinal trunk muscles, the predictions are excellent throughout.

Abdominal Muscles↗

PubMed1988

Isokinetic trunk and lifting strength measurements: variability as an indicator of effort.

This study examines the hypothesis that force/distance curve variability distinguishes submaximal from maximal efforts in isokinetic trunk and lifting strength tests. Thirty normal subjects were tested on the Cybex Trunk Extension/Flexion (TEF) and Liftask (LT) machines during maximal (100%) and submaximal (50%) efforts. Considering each test separately, visual assessments of curve variability were indeterminate of degree of effort in 28% of TEF and 34% of LT tests. Measurement models of curve variability were more clearly discriminating. When a given subject's test curves were considered together, scaled visual assessments identified the degree of effort in 91% of TEF and 86% of LT results. The measurement models were accurate 90-92% of TEF and 79-92% of LT results. Clinical judgment is required in evaluating effort during tests of isokinetic trunk and lifting strength.

Adult↗

PubMed1991

Reliability of isokinetic measurements of trunk muscle performance.

The purpose of this investigation was to assess the reliability of isokinetic trunk muscle performance. Sixty-one volunteers participated (29 men, 32 women; age range, 20-60 years). All subjects were without low-back symptoms at the time of testing. All testing was performed with the subject initially standing, using speeds of 60, 120, and 180 degrees per second. Ten repetitions of flexion and extension were performed reciprocally at each speed, with a 3-minute rest period between speeds. Test-retest intervals were 1 and 3 weeks from the initial test. Peak torque-to-body-weight ratios, extension-to-flexion ratios, and average work per repetition were calculated for each speed for flexion and extension. Data were analyzed with analysis of variance, intraclass correlation coefficients, and Pearson correlation coefficients. Intraclass correlation coefficient values ranged from .74 to .88 for measurements derived from peak torque, and from .88-.93 for measurements derived from work (with the exception of .69 for men at 180 degrees/sec). Standard error of measurements ranged from 8 to 32 ft-lb, with a tendency to increase with increasing speeds. It was concluded that, when using this protocol, isokinetic measurements of muscle function offer the clinician sensitive and reliable measurements of trunk muscle performance and that incorporating increased practice with women and longer rest periods with men may further decrease error associated with these isokinetic trunk strength measurements.

Adult↗

PubMed1993

Trunk asymmetry, posture, growth, and risk of scoliosis. A three-year follow-up of Finnish prepubertal school children.

Several anthropometric measurements were studied for their prediction of scoliosis in 896 children (430 girls and 466 boys) who were free from scoliosis at entry. The children were examined annually from the average age of 10.8 to 13.8 years to follow up their trunk asymmetry, posture, and growth. Scoliosis developed in 24 boys and 41 girls (Cobb angle > or = 10 degrees in a posteroanterior standing radiograph) during the 3 years. In both girls and boys, trunk asymmetry measured by the forward bending test was found to be the most powerful determinant of the incidence of scoliosis. In the whole cohort the adjusted odds ratio was 1.61 and its 95% confidence interval was 1.42-1.82 per one millimeter increase in trunk hump. Using spinal pantography the degree of thoracic kyphosis in girls (odds ratio = 1.05, 95% confidence interval = 1.01-1.09, per one degree) and the degree of lumbar lordosis in boys (odds ratio = 1.07, 95% confidence interval = 1.01-1.13, per one degree) were significant predictors of future scoliosis. In the children both sexes who eventually had scoliosis, body height, sitting height, and growth of sitting height were greater than in other children, but these factors carried no statistical significance in the logistic analyses. There were differences between the prescoliotic girls and other girls in both mean age (11.8 vs 12.1 years, P = 0.02) and value (5.5 cm vs 6.1 cm/yr, P = 0.08) of peak sitting height velocity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1993

Magnetic resonance imaging of the discs and trunk muscles in patients with chronic low back pain and healthy control subjects.

This study aimed to evaluate the lumbar intervertebral discs and the maximum isometric strength and size of the trunk muscles of middle-aged healthy volunteers (60 persons) and low back pain patients (48 persons). Disc degeneration was more frequently seen in the patients than in the healthy volunteers. The psoas and back muscles (erector spinae and multifidus) of the patients were smaller than those of the volunteers. Patients had also more fat deposits in the back muscles than controls. The maximum isometric strength of trunk muscles of the patients was on average weaker than that of the volunteers. However, the size of the back muscles was not related to the maximum isometric extension strength of the trunk.

Adipose Tissue↗

PubMed1996

Trunk extensor and flexor strength measured by the Cybex 6000 dynamometer. Assessment of short-term and long-term reproducibility of several strength variables.

STUDY DESIGN: Isokinetic trunk extensor and flexor strength (peak torque, total work, power acceleration time, and torque acceleration energy) at 30 degrees/sec, 120 degrees/sec, and 180 degrees/sec and isometric extensor and flexor peak torque were measured in 24 healthy women. Measurements were performed in three separate sessions at the same time of day and by the same experienced examiner. The number of days between Session 1 and Session 2 and between Session 1 and Session 3 ranged from 1 to 7 (median, 2 days) and from 23 to 48 (median, 32 days), respectively. The test results were not revealed before all sessions were completed. OBJECTIVES: To determine the intrasession, short-term, and long-term reproducibility of several trunk strength variables measured by the Cybex 6000 isokinetic dynamometer (Lumex, Inc., Ronkonkoma, NY). SUMMARY OF BACKGROUND DATA: Only few and insufficient data regarding the reproducibility of trunk strength measurements exist. Previous studies have focused on coefficients of correlation to express reproducibility. Correlations, however, are misleading and inappropriate for this purpose. The critical difference is the difference between two results that would be statistically significant when applied to a reference group in steady state. The critical difference in percentage is calculated as 2.77 X coefficient of variation (%). METHODS: Isokinetic dynamometry (Cybex 6000). Reproducibility was expressed as pooled coefficients of variation, individual coefficients of variation, and critical differences. RESULTS: Substantial between-subject variation of coefficients of variation was found for all strength variables; for example, the 80% central range for individual coefficients of variation for long-term reproducibility of extensor strength measurements at 30 degrees/sec ranged from 2.5% to 19.5%. Critical differences calculated using the pooled variances for long-term reproducibility were higher than 20% for all measures, mounting to 80% for acceleration time. CONCLUSIONS: Strength testing is of limited value in the individual subject because of considerable day-to-day variability. This finding has important clinical implications.

Adolescent↗

PubMed1998

Relation between functional characteristics of the trunk and the occurrence of low back pain. Associated risk factors.

STUDY DESIGN: A 2-year prospective study relating a set of subject characteristics (professional and extraprofessional constraints, personal and anthropometric characteristics, and static and dynamic performance of the trunk) and incidence of low back pain in a population of male Belgian steel workers. OBJECTIVES: To investigate the relation between occurrence of new cases of low back pain and prior personal, anthropometric, or functional characteristics. SUMMARY OF BACKGROUND DATA: Some functional characteristics--in particular, dynamic parameters of the trunk such as the velocity--have been shown to be significantly reduced for low back pain in workers in cross-sectional studies. The question remained as to whether modifications of these parameters preceded the development of low back pain. METHODS: The protocol included a questionnaire, a clinical examination, anthropometric measurements, and a set of functional tests on an isoinertial dynamometer. It was carried out twice, after a 1-year interval, on a sample of 215 workers without any history of low back pain. The reports of low back pain were again investigated 1 year later. RESULTS: The development of low back pain is related to frontal plane imbalance of the trunk, lower body weight, and perception of heavy lifting efforts at the workplace. Individuals performing dynamic tests at higher velocities appear also to be at a greater risk of low back pain. CONCLUSIONS: Although workers with a history of low back pain performed dynamic tests at significantly lower velocities, the probability for development of low back pain in the following year is greater for workers performing such tests at greater velocities.

Adult↗

PubMed2000

Repositioning error in low back pain. Comparing trunk repositioning error in subjects with chronic low back pain and control subjects.

STUDY DESIGN: Repositioning error of the trunk was tested in 20 subjects with chronic low back pain and in 20 control subjects. The 3Space Tracker (Polhemus, Colchester, VT), a device that measures three-dimensional position in space, was used to determine the subject's trunk position. OBJECTIVES: To determine whether repositioning error is different in subjects with chronic low back pain than in control subjects. SUMMARY OF BACKGROUND DATA: Proprioception allows the body to maintain proper orientation during static and dynamic activities. In peripheral joint injuries, researchers have demonstrated a loss of some aspects of proprioception and improvement in outcome with retraining. Although the components of proprioception in subjects with low back pain have not been well studied, it is thought that these persons lose some elements of proprioception that can be measured in a quantifiable way. If so, then rehabilitation to improve these deficits is important. In this pilot study, one aspect of proprioception, repositioning error, was examined. METHODS: The subjects attempted to replicate target positions of the trunk in flexion, extension, lateral bending, and lateral rotation. Repositioning error was calculated as the absolute difference between the actual and the subject-replicated target positions. RESULTS: No significant difference was found in repositioning error between the control subjects and the persons with chronic low back pain. CONCLUSIONS: Because proprioception is complex and entails the use of many afferent receptors, it is difficult to measure any one afferent deficiency discretely. The authors believe that this study, in which one aspect of proprioception was measured in an indirect manner, provides important background information on low back position sense. Further studies analyzing aspects of proprioception in subjects with low back pain are recommended.

Adult↗

PubMed2000

Sensory innervation of the lumbar dura mater passing through the sympathetic trunk in rats.

STUDY DESIGN: Sensory innervation of the lumbar dura mater passing through the sympathetic trunk was investigated by neuronal tracing and immunohistochemical methods. OBJECTIVE: To assess an anatomic basis indicating that sympathetic block in the higher lumbar region is effective for patients with low back pain. SUMMARY OF BACKGROUND DATA: Low back pain is elicited by disorder or mechanical stimulation of the lumbar dura mater. Clinically, the authors often have observed patients in whom root block at the responsible level or sympathetic block at the higher level could relieve low back pain. Therefore, there may be two different sensory routes, the segmental innervation at the same level and nonsegmental fibers from higher dorsal root ganglia. METHODS: The tracers were injected into the sympathetic trunk between L3 and L4 of rats. The lumbar dorsal root ganglia and dura mater were examined, and labeled cells were measured in size and the distribution. To establish the sensory property, the materials were processed in immunohistochemistry for calcitonin gene-related peptide. RESULTS: Many small- to medium-sized neurons were retrogradely labeled L1 and L2 dorsal root ganglia after injection into the sympathetic trunk. The anterogradely labeled fibers were found in the dura mater at L4 and L5. Some of the labeled neurons and fibers were immunoreactive for calcitonin gene-related peptide. CONCLUSION: Sensory fibers from the upper lumbar ganglia innervated the lower lumbar dura mater directly. These sensory nerves may mediate low back pain and possibly interact with sympathetic nerves.

Animals↗