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At least 253 records · Page 14Linked to original sources

PubMed1999

Geometric measurements of the lumbar spine in Chinese men during trunk flexion.

STUDY DESIGN: An analysis of the geometric data of the lumbar spine in Chinese men. Lateral radiographs were obtained of 16 men in the upright position to a trunk flexion of 90 degrees in 30 degrees increments. OBJECTIVES: To establish reference data concerning the geometry of the lumbar spine for various degrees of trunk flexion. SUMMARY OF BACKGROUND DATA: In previous studies, the morphometry and alignment of the lumbar spine have been investigated. Reports of systematic analyses of the lumbar spine in trunk flexion have lacked adequate radiographic data. Moreover, few studies have focused on measuring lumbar spine geometric data in Chinese individuals. METHODS: A total of 67 landmarks on each radiograph were identified. They were marked by investigators and digitized using a HyperSpace digitizing system (V.17: Mira Imaging Inc., Salt Lake City, UT). The geometric configuration of the vertebrae and discs then was derived from the digitized points. RESULTS: The dimensions of the vertebrae and disc on the lumbar spine obtained in this study were similar to those of previous studies. The motion of the lumbosacral spine had the greatest contribution in trunk flexion, approximately 90% (i.e., rotating at the rate of 9 degrees for each 10 degrees of trunk flexion) when the trunk was flexed from 30 degrees to 60 degrees. After that, the hips were dominant in accomplishing the trunk flexion from 60 degrees to horizontal. This motion patterns may be useful for making clinical diagnoses of lumbar function in Chinese men. CONCLUSIONS: No obvious interracial differences were found in the geometric data found in this study, which suggests that morphometric data obtained from Caucasian individuals may be applied to Chinese patients for clinical purposes.

Adult↗

PubMed2002

Posture-dependent isometric trunk extension and flexion strength in normal male and female subjects.

The objective of this study was to quantify the relationship between trunk posture and trunk muscle function in a group of young, normal male and female subjects. Ten male and 10 female subjects performed isometric flexion and extension tasks using a trunk dynamometer. Peak isometric torque was recorded in flexion and extension at 10 degrees increments over a sagittal posture range of -20 degrees extension to +50 degrees of flexion. Significant differences in trunk strength (isometric torque) were found between males and females, at various sagittal plane trunk postures, and between flexion (F) and extension (E) tasks. Flexion torque was greatest at 20 degrees to 30 degrees flexion, whereas extension torque was greatest at 50 degrees flexion. Gender-specific differences in trunk strength were markedly reduced when the torque data were normalized by the subject's height multiplied by body weight. The E/F torque ratio showed a relatively linear, over twofold increase with increasing flexion angle, and was significantly greater for female subjects compared with male subjects at most sagittal postures. The baseline trunk isometric strength data provided by this study should help clinicians to use strength testing more precisely and specifically in prevention and diagnosis of patients at risk for back disorders.

Adult↗

PubMed2005

Isokinetic muscle strength of the trunk and bilateral knees in young subjects with lumbar disc herniation.

STUDY DESIGN: Cross-sectional study comparing normal subjects and patients with lumbar disc herniation. OBJECTIVE: To evaluate trunk and knee muscle strength in patients with L4-L5 and/or L5-S1 disc herniation. SUMMARY OF BACKGROUND DATA: Numerous studies have shown that patients with low back pain have weaker trunk muscles. The strength of trunk and knee muscles has not been investigated simultaneously in patients with lumbar disc herniation. METHODS: Forty-one controls and 2 patients were included. Isokinetic strength of the trunk and bilateral knees was tested on a calibrated isokinetic testing machine (Biodex System 3 Pro) regardless of the laterality of the radiculopathy. The testing was carrying out at two different velocities: 60 degrees and 120 degrees per second. RESULTS: Total trunk strength and knee strength were significantly lower in these patients (4.34 +/- 1.06 and 4.06 +/- 1.16 vs. 6.21 +/- 1.05 and 5.83 +/- 1.09 Nm/kg at 60 degrees and 120 degrees per second, respectively, P < 0.001). In patients with unilateral sciatica, there was no significant difference (P > 0.05) in unilateral knee strength between sciatica-involved and -uninvolved limbs (1.89 +/- 0.5, 1.08 +/- 0.45, 1.48 +/- 0.58, 0.93 +/- 0.41 vs. 1.68 +/- 0.45, 0.91 +/- 0.38, 1.41 +/- 0.48, 0.79 +/- 0.39 Nm/kg in sciatica-uninvolved vs. sciatica-involved limbs during extension and flexion at 60 degrees and 120 degrees per second, respectively). Total trunk strength was significantly correlated with total knee strength in both groups. CONCLUSIONS: In the patients with lumbar disc herniation, muscle strength of the trunk and knees was decreased to a similar extent. Weaker knee strength was found on either side of the lower extremity in the patients with unilateral sciatica, regardless of its location.

Adult↗

PubMed2006

Effects of pelvic asymmetry and low back pain on trunk kinematics during sitting: a comparison with standing.

STUDY DESIGN: A prospective study was conducted on a group of patients with unilateral nonspecific low back pain (LBP) and healthy controls. OBJECTIVES: To answer 3 questions: (1) Does pelvic asymmetry measured in standing affect the dynamics of motion performed in sitting? (2) Do patients with LBP perform trunk motions differently from non-LBP participants in sitting position? and (3) Do the kinematics of lateral flexion and axial rotation differ between sitting and standing positions? SUMMARY OF BACKGROUND DATA: The effect of pelvic asymmetry on trunk motion while sitting remains unclear. LBP has been associated with altered trunk kinematics in standing; however, there is limited information available describing trunk kinematics in sitting position in comparison to standing. METHODS: Pelvic asymmetry was measured in 54 patients with unilateral nonspecific LBP and 59 control subjects. A motion-analysis system was used to test the range and symmetry of lateral flexion and axial rotation in sitting and standing positions. Bivariate correlations, regression, multivariate analysis of variance, and paired sample t tests were used to test for associations between variables and differences between groups. RESULTS: We found significant: (1) correlations between pelvic asymmetry and asymmetric trunk motion performed in sitting, (2) differences between the LBP and control groups in patterns of trunk motion performed in a sitting posture, and (3) differences between kinematics of motions performed in sitting versus standing postures. CONCLUSIONS: This study shows a link between pelvic asymmetry and altered trunk motion in sitting position. We suggest that people with LBP may have a distinct compensatory mechanism, secondary to pelvic asymmetry, which puts the lumbar spine under higher stress. Movement asymmetry, rather than range of motion, may be a better indicator of disturbed function for people with LBP. Structural and functional asymmetries are factors that may be considered in the seating design and work environment.

Adult↗

PubMed2005

Effect of trunk flexion on the occupant neck response to anterolateral whiplash impacts.

OBJECTIVE: The purpose of this study was to determine the response of the cervical muscles to increasing low-velocity anterolateral impacts with the volunteer's trunk flexed to the right and left. METHODS: A total of 20 healthy volunteers were subjected to left anterolateral impacts of 4.0, 7.6, 10.7, and 13.4 m/sec and, sequentially, with trunk flexed either left or right. Bilateral electromyograms (EMGs) of the sternocleidomastoids, trapezii, and splenii capitis were recorded. DESIGN: At an acceleration of 13.4 m/sec, with the trunk flexed left, the left trapezius generated 48% of its maximal voluntary contraction EMG, whereas the right trapezius (contralateral to the left anterolateral impact) generated 38% of this variable. All other muscle generated </=23% of their maximal voluntary contraction EMG, a significant difference from the trapezii (P = 0.005). Similarly, with the trunk flexed to the right under these same conditions, the left trapezius generated 26% and the right trapezius 35% of their maximal voluntary contraction EMG. Again, all other muscles generated significantly less EMG activity, </=22% (P = 0.009). Overall, the EMG responses were of low magnitude compared with known data with the trunk in neutral posture in this direction of impact. CONCLUSIONS: When the subject sits with trunk flexed out of neutral posture at the time of an anterolateral impact, the cervical muscle response is reduced compared with anterolateral impacts with the trunk in neutral posture.

Acceleration↗

PubMed2006

A two-year prospective analysis of trunk function in TRAM breast reconstructions.

BACKGROUND: Functional outcomes in breast reconstruction are important quality measures and aid in patients' decision-making process. To address the concerns of abdominal wall morbidity with transverse rectus abdominis musculocutaneous (TRAM) flap reconstructions, the authors prospectively evaluated the long-term effects of postmastectomy breast reconstruction on trunk function using objective clinical measures. METHODS: Using a multicenter prospective cohort design, they recruited women undergoing first-time immediate or delayed breast reconstructions from 12 centers and 23 plastic surgeons. Trunk functional data, objectively measured with Cybex machines, for patients with an expander/implant, pedicle TRAM, and free TRAM reconstructions were evaluated preoperatively and at postoperative years 1 and 2 in 183 patients. The effects of procedure type, timing, and laterality on trunk peak torque and range of motion were analyzed using linear regression. RESULTS: At 2 years postoperatively, procedure type, timing, and laterality did not significantly affect the range of motion for trunk flexion and extension. Peak torque for trunk flexion at year 2 was significantly decreased in patients with TRAM compared with expander/implant reconstructions (p < 0.05), with a 6 to 19 percent decrease in flexion peak torque. However, no significant difference in flexion peak torque was found between patients with free and pedicle TRAM reconstructions. CONCLUSIONS: The authors found that (1) breast cancer patients with TRAM reconstructions had a less than 20 percent long-term deficit in trunk flexion peak torque and (2) there was no significant difference in trunk function between patients receiving pedicle and free TRAM reconstructions.

Biomechanical Phenomena↗

PubMed2006

Contribution of the corpus callosum to bilateral representation of the trunk midline in the human brain: an fMRI study of callosotomized patients.

Human brain studies have shown that the cutaneous receptors of trunk regions close to the midline are represented in the first somatosensory cortex (SI) of both hemispheres. The present study aims to establish whether in humans, as in non-human primates, the bilateral representation of the trunk midline in area SI depends on the corpus callosum. Data were obtained from eight callosotomized patients: three with complete callosal resection, one with a partial posterior resection including the splenium and the callosal trunk, and four with partial anterior resections sparing the splenium and in one case also the posterior part of the callosal trunk. The investigation was carried out with functional magnetic resonance imaging. Unilateral tactile stimulation was applied by rubbing ventral trunk regions close to the midline (about 20 x 10 cm in width) with a soft cotton pad (frequency 1 Hz). Cortical activation foci elicited by unilateral stimulation of cutaneous regions adjacent to the midline were detected in the contralateral post-central gyrus (PCG), in a region corresponding to the trunk ventral midline representation zone of area SI, as described in a previous study of intact subjects. In most patients, activation foci were also found in the ipsilateral PCG, again as in subjects with an intact corpus callosum. The data confirm that the skin regions adjacent to the trunk midline are represented bilaterally in SI, and indicate that ipsilateral activation is at least partially independent of the corpus callosum.

Abdomen↗

PubMed2004

Disruption of coordination between arm, trunk, and center of pressure displacement in patients with hemiparesis.

To determine how arm movements influence postural sway in the upright position after stroke, interactions between arm, trunk, and center of pressure (CoP) displacements in the sagittal direction were investigated in participants with hemiparesis and healthy subjects. Participants swung both arms sagittally in either of 2 directions (in-phase, anti-phase) and at 2 speeds (preferred, fast) while standing on separate force plates. Variables measured included amplitude and frequency of arm swinging, shoulder and trunk range of motion, CoP displacements under each foot and of the whole body, and the relationships between the arm, trunk, and CoP displacements. CoP displacements under the non-paretic leg were greater than those under the paretic leg, which may in part be related to the larger amplitude of swinging of the non-paretic arm. CoP displacements under each foot were not related to arm swinging during in-phase swinging at the preferred speed in healthy subjects. When speed of arm swinging was increased, however, the CoP moved in a direction opposite to the arm movement. In contrast, in individuals with hemiparesis, CoPs and arms moved in the same direction for both speeds. During anti-phase swinging in healthy subjects, the trunk counterbalanced the arm movements, while in participants with hemiparesis, the trunk moved with the affected arm. Results show that stroke resulted in abnormal patterns of arm-trunk-CoP interactions that may be related to a greater involvement of the trunk in arm transport, an altered pattern of coordination between arm and CoP displacements, and an impaired ability of the damaged nervous system to adapt postural synergies to changes in movement velocity.

Adult↗

PubMed2003

Head-trunk coordination during linear anterior-posterior translations.

The purpose of this study was to evaluate the relative contributions of inputs from the vestibular system and the trunk to head-trunk coordination. Twelve healthy adults and 6 adults with diminished bilateral labyrinthine input (LD) were seated with their trunk either fixed to the seat or free to move. Subjects received 10-cm, 445-cm/s(2) anterior-posterior ramps and 0.35- to 4.05-Hz sum-of-sines translations while performing a mental distraction task in the dark. Kinematics of the head and trunk were derived from an Optotrak motion analysis system and a linear accelerometer placed on the head. EMG signals were collected from neck and paraspinal muscles. Data were tested for significance with multivariate ANOVA (MANOVA) and Bonferroni post hoc analyses. Initial linear and angular head acceleration directions differed in healthy subjects when the trunk was fixed or free, but did not differ in LD subjects. Peak head angular accelerations were significantly greater with the trunk fixed than when free, and were greater in LD than in control subjects. EMG response latencies did not differ when the trunk was fixed or free. Low-frequency phase responses in the healthy subjects were close to 90 degrees and had a delayed descent as frequency increased, suggesting some neural compensation that was absent in the LD subjects. Results of this study revealed a strong initial reliance on system mechanics and on signals from segmental receptors. The vestibular system may act to damp later response components and to monitor the position of the head in space secondary to feedback from segmental proprioceptors rather than to generate the postural reactions.

Acceleration↗

PubMed1985

The branches of the celiac trunk.

156 abdominal preparations were explored by arteriography, corrosion and dissection. Classification of the celiac trunk becomes easy if one considers the trunk to be composed of three main stems: the splenic, the hepatic and the left gastric artery, other vessels being less important collaterals. Usually, the celiac trunk bifurcates into the splenic and the hepatic artery; the left gastric artery is a mobile vessel whose origin may slide between the aorta, all over the celiac trunk up to a trifurcation. The direction of the celiac trunk is influenced by the topography of the pancreatic neck and by the origin of the hepatic artery: if the celiac trunk is not the origin of the hepatic artery it is not directed to the right but to the left. It is the hepatic artery that pulls the celiac trunk to the right. Variations in the origin of the splenic artery are exceptional. In contrast to adults, the diameter of the hepatic artery in young children is larger than that of the splenic artery.

Angiography↗

PubMed2005

Task-specific training with trunk restraint on arm recovery in stroke: randomized control trial.

BACKGROUND AND PURPOSE: Task-specific training improves functional outcomes after stroke. However, gains may be accompanied by increases in movements compensating for motor impairments. We hypothesized that restriction of compensatory trunk movements may encourage recovery of premorbid movement patterns leading to better functional outcomes. The goal was to determine whether task-specific training with trunk-restraint (TR) produces greater improvements in arm impairment and function than training without TR in patients with chronic hemiparesis. METHODS: Double-blind randomized control trial of a therapist-supervised home program (3 times per week, 5 weeks) in 30 patients with chronic hemiparesis stratified by arm impairment level (Fugl-Meyer) was performed. Intervention group (TR group) received progressive object-related reach-to-grasp training with prevention of trunk movements. Control group (C) practiced tasks without TR. Main outcome measures were upper limb impairment (Fugl-Meyer Arm Section) and function (TEMPA) and movement kinematics (trunk displacement, elbow extension; Optotrak, 10 trials) of a reach-to-grasp movement. Evaluations were repeated before, immediately after, and 1 month postintervention by blind evaluators. RESULTS: TR training led to greater improvements in impairment and function compared with C. Improvements were accompanied by increased active joint range and were greater in initially more severe patients. In these patients, TR decreased trunk movement and increased elbow extension, whereas C had opposite effects (increased compensatory movements). In TR, changes in arm function were correlated with changes in arm and trunk kinematics. CONCLUSIONS: Treatment should be tailored to arm impairment severity with particular attention to controlling excessive trunk movements if the goal is to improve arm movement quality and function.

Aged↗

PubMed2006

Analysis of right anterolateral impacts: the effect of trunk flexion on the cervical muscle whiplash response.

BACKGROUND: The cervical muscles are considered a potential site of whiplash injury, and there is a need to understand the cervical muscle response under non-conventional whiplash impact scenarios, including variable body position and impact direction. There is no data, however, on the effect of occupant position on the muscle response to frontal impacts. Therefore, the objective of the study was to measure cervical muscle response to graded right anterolateral impacts. METHODS: Twenty volunteers were subjected to right anterolateral impacts of 4.3, 7.8, 10.6, and 12.8 m/s(2) acceleration with their trunk flexed forward 45 degrees and laterally flexed right or left by 45 degrees. Bilateral EMG of the sternocleidomastoids, trapezii, and splenii capitis and acceleration of the sled, torso, and head were measured. RESULTS AND DISCUSSION: With either direction of trunk flexion at impact, the trapezius EMGs increased with increasing acceleration (p < 0.05). Time to onset of the electromyogram and time to peak electromyogram for most muscles showed a trend towards decreasing with increasing acceleration. With trunk flexion to the left, the left trapezius generated 38% of its maximal voluntary contraction (MVC) EMG, while the right trapezius generated 28% of its MVC EMG. All other muscles generated 25% or less of this measure (25% for the left splenius capitis, 8% for the right splenius capitis, 6% for the left sternocleidomastoid, and 2% for the left sterncleidomastoid). Conversely, with the trunk flexed to the right, the right trapezius generated 44% of its MVC EMG, while the left trapezius generated 31% of this value, and all other muscles generated 20% or less of their MVC EMG (20% for the left splenius capitis, 14% for the right splenius capitis, 4% for both the left and right sternocleidomastoids). CONCLUSION: When the subject sits with trunk flexed out of neutral posture at the time of anterolateral impact, the cervical muscle response is dramatically reduced compared to frontal impacts with the trunk in neutral posture. In the absence of bodily impact, the flexed trunk posture appears to produce a biomechanical response that would decrease the likelihood of cervical muscle injury in low velocity impacts.

Journal Article↗

PubMed1999

Trunk kinematics in hemiplegic gait and the effect of walking aids.

OBJECTIVE: To establish baseline measurements of trunk movements during hemiplegic gait, to assess the relationship between trunk movements and walking ability, and to investigate the effect of walking aids on the trunk movements. METHOD: Twenty subjects with a chronic hemiplegia from a stroke, who could walk independently, were recruited. Lateral and vertical movements of the pelvis, and symmetry of these movements were measured using CODA (a three-dimensional movement analysis system) as the subjects walked at their own pace without an aid. They were also tested as they walked with a stick and a tripod to assess the effect of different walking aids. Mean values for the trunk movements and symmetry were calculated, Pearson's correlations assessed the relationship between each trunk movement and gait velocity (a measure of overall walking ability), and the influence of the different aids was assessed using a one-way repeated measures ANOVA. RESULTS: Lateral displacement was large (mean = 9.9 cm, SD 3.9) and orientated to the sound side, vertical displacement was small (mean = 2.45 cm, SD 1.4). The movements showed marked asymmetry which favoured the hemiplegic side in that there was less movement of, or towards this side. There was a significant relationship (at 5% level) between walking ability and lateral movements (r = 0.6), but not vertical movements (r= 0.41). No significant differences were found with the different aids. CONCLUSION: These results give baseline values for trunk movements during hemiplegic gait and the relationship between the movements and walking ability. The use of walking aid and the type of walking aid did not affect the subjects' trunk movements or walking ability.

Biomechanical Phenomena↗

PubMed2004

Normal and aberrant craniofacial myogenesis by grafted trunk somitic and segmental plate mesoderm.

Our research assesses the ability of three trunk mesodermal populations -- medial and lateral halves of newly formed somites, and presomitic (segmental plate) mesenchyme -- to participate in the differentiation and morphogenesis of craniofacial muscles. Grafts from quail donor embryos were placed in mesodermal pockets adjacent to the midbrain-hindbrain boundary, prior to the onset of neural crest migration, in chick host embryos. This encompasses the site where the lateral rectus and the proximal first branchial arch muscle primordia arise. The distribution and differentiation of graft-derived cells were assayed using QCPN and QH1 antibodies to identify all quail cells and quail endothelial cells, respectively. Chimeric embryos were assayed for expression of myf5, myod, paraxis and lbx1, and the synthesis of myosin heavy chain (MyHC), between 1 and 6 days later (stages 14-30). Heterotopic and control (orthotopic) transplants consistently produced invasive angioblasts, and contributed to the lateral rectus and proximal first branchial arch muscles; many also contributed to the dorsal oblique muscle. The spatiotemporal patterns of transcription factor and MyHC expression by these trunk cells mimicked those of normal head muscles. Heterotopic grafts also gave rise to many ectopic muscles. These were observed in somite-like condensations at the implant site, in dense mesenchymal aggregates adjacent to the midbrain-hindbrain boundary, and in numerous small condensations scattered deep to the dorsal margin of the eye. Cells in ectopic condensations expressed trunk transcription factors and differentiated rapidly, mimicking the trunk myogenic timetable. A novel discovery was the formation by grafted trunk mesoderm of many mononucleated myocytes and irregularly oriented myotubes deep to the eye. These results establish that the head environment is able to support the progressive differentiation of several distinct trunk myogenic progenitor populations, over-riding whatever biases were present at the time of grafting. The spatial and temporal control of head muscle differentiation and morphogenesis are very site specific, and head mesoderm outside of these sites is normally refractory to, or inhibited by, the signals that initiate ectopic myogenesis by grafted trunk mesoderm cells.

Animals↗

PubMed1998

Molecular identification of spadetail: regulation of zebrafish trunk and tail mesoderm formation by T-box genes.

Inhibition of fibroblast growth factor (FGF) signaling prevents trunk and tail formation in Xenopus and zebrafish embryos. While the T-box transcription factor Brachyury (called No Tail in zebrafish) is a key mediator of FGF signaling in the notochord and tail, the pathways activated by FGF in non-notochordal trunk mesoderm have been uncertain. Previous studies have shown that the spadetail gene is required for non-notochordal trunk mesoderm formation; spadetail mutant embryos have major trunk mesoderm deficiencies, but relatively normal tail and notochord development. We demonstrate here that spadetail encodes a T-box transcription factor with homologues in Xenopus and chick. Spadetail is likely to be a key mediator of FGF signaling in trunk non-notochordal mesoderm, since spadetail expression is regulated by FGF signaling. Trunk and tail development are therefore dependent upon the complementary actions of two T-box genes, spadetail and no tail. We show that the regulatory hierarchy among spadetail, no tail and a third T-box gene, tbx6, are substantially different during trunk and tail mesoderm formation, and propose a genetic model that accounts for the regional phenotypes of spadetail and no tail mutants.

Amino Acid Sequence↗

PubMed2000

Crustacean (malacostracan) Hox genes and the evolution of the arthropod trunk.

Representatives of the Insecta and the Malacostraca (higher crustaceans) have highly derived body plans subdivided into several tagma, groups of segments united by a common function and/or morphology. The tagmatization of segments in the trunk, the part of the body between head and telson, in both lineages is thought to have evolved independently from ancestors with a distinct head but a homonomous, undifferentiated trunk. In the branchiopod crustacean, Artemia franciscana, the trunk Hox genes are expressed in broad overlapping domains suggesting a conserved ancestral state (Averof, M. and Akam, M. (1995) Nature 376, 420-423). In comparison, in insects, the Antennapedia-class genes of the homeotic clusters are more regionally deployed into distinct domains where they serve to control the morphology of the different trunk segments. Thus an originally Artemia-like pattern of homeotic gene expression has apparently been modified in the insect lineage associated with and perhaps facilitating the observed pattern of tagmatization. Since insects are the only arthropods with a derived trunk tagmosis tested to date, we examined the expression patterns of the Hox genes Antp, Ubx and abd-A in the malacostracan crustacean Porcellio scaber (Oniscidae, Isopoda). We found that, unlike the pattern seen in Artemia, these genes are expressed in well-defined discrete domains coinciding with tagmatic boundaries which are distinct from those of the insects. Our observations suggest that, during the independent tagmatization in insects and malacostracan crustaceans, the homologous 'trunk' genes evolved to perform different developmental functions. We also propose that, in each lineage, the changes in Hox gene expression pattern may have been important in trunk tagmatization.

Amino Acid Sequence↗

PubMed2004

Stabilization and mobility of the head and trunk in vervet monkeys (Cercopithecus aethiops) during treadmill walks and gallops.

The brain requires internal or external reference frames to determine body orientation in space. These frames may change, however, to meet changing conditions. During quadrupedal overground locomotion by monkeys, the head rotates on a stabilized trunk during walking, but the trunk rotates on a stabilized head during galloping. Do the same movement patterns occur during in-place locomotion? Head and trunk pitch rotations were measured, and yaw and roll rotations estimated from cine films of three adult vervet monkeys (Cercopithecus aethiops L. 1758) walking and galloping quadrupedally on a treadmill. Head and trunk rotational patterns during treadmill walks were comparable to the patterns found during overground walks. The rotational velocities of these segments during both treadmill walks and gallops were also comparable to the velocities found during natural locomotion. By contrast, whereas head and trunk rotational patterns during treadmill gallops did occur that were comparable to the patterns practiced during overground gallops, a significantly different pattern involving large and simultaneous head and trunk rotations was more commonly observed. Simultaneous head and trunk rotations may be possible during treadmill gallops because the fixed visual surround is providing an adequate spatial reference frame. Alternatively, or in addition to this visual information, a re-weighting in other sensory modalities may be occurring. Specifically, the vestibular inputs used during overground locomotion to reference gravity or a gravity-derived vector may become less important than proprioceptive inputs that are using the treadmill belt surface as a reference. Regardless, the spatial reference frame being used, blinks that occur at specific times during the largest head yaw rotations may be necessary to avoid the initiation of unwanted and potentially destabilizing lateral sway brought on by sudden increases in optic flow velocity.

Animals↗

PubMed2006

The energetic costs of trunk and distal-limb loading during walking and running in guinea fowl Numida meleagris: II. Muscle energy use as indicated by blood flow.

We examined the changes in muscle energy use in guinea fowl running at 1.5 m s-1 either unloaded, or carrying trunk loads equal to 23% of body mass, or loads on their distal legs equal to a total of 5% of body mass. We estimated muscle energy use by measuring blood flow to all of the leg muscles using injected microspheres. Total blood flow to the leg muscles increased by approximately 15% under both loading conditions, which matched the percentage increase in net organismal metabolic rate. Significant increases in energy use (inferred from blood flow) above that found in unloaded birds were found in 12 muscles in trunk-loaded birds, with most of the increases restricted to stance-phase muscles, as predicted. Just three of these muscles, the femerotibialis, the iliotibialis lateralis pars postacetabularis and the fibularis longus accounted for 70% of the increased energy use. Noticeably absent from the group of muscles that increased energy use during trunk loading were several large biarticular muscles that have extensor actions at the hip or ankle, but flexor actions at the knee. We concluded that the low energetic cost of carrying trunk loads in guinea fowl may rely on the activation of a group of muscles that together provide support and propulsion across all the major joints, without producing opposing moments at other joints that could potentially waste energy. The specific leg muscles responsible for the increase in metabolism during trunk loading also suggest that the energy cost of producing mechanical work may be an important determinant of the cost of carrying extra mass on the trunk. During distal-limb loading, eleven leg muscles had significant increases in energy use, but unlike during trunk loading, both stance- and swing-phase muscles had large increases in energy use. This distribution of energy use between stance and swing agrees with the prediction that increased mechanical work determines the cost of limb loading, because a substantial fraction of the increased segmental work during distal-limb loading in guinea fowl has been found to occur during stance.

Animals↗