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PubMed2005

Comparison between leg and arm eccentric exercises of the same relative intensity on indices of muscle damage.

Many exercise models have demonstrated associations between eccentric muscle actions and muscle damage. However, the magnitude of muscle damage varies among the models. It appears that responses to eccentric exercise are different between leg and arm muscles but this has not been systematically clarified. This study compared leg and arm eccentric exercises of the same relative intensity for indices of muscle damage. Eleven healthy untrained males [Age: 21.2 (1.0) years, Height: 179.4 (3.0) cm, Weight: 78.4 (3.1) kg] performed a sub-maximal eccentric exercise of the knee extensors (LEGS) and the elbow flexors (ARMS), separately. Both LEGS and ARMS consisted of six sets of 12 repetitions with an intensity corresponding to 75% of the predetermined maximal eccentric peak torque (EPT) of each muscle. Range of motion (ROM), delayed onset muscle soreness (DOMS), serum creatine kinase (CK) and lactate dehydrogenase (LDH) activities, myoglobin (Mb) concentration, and muscle strength [EPT and isometric peak torque (IPT)] were assessed before and 24, 48, 72, and 96 h following exercise. Significant (P < 0.05) changes in DOMS and ROM were observed up to 96 h after both exercise bouts, and the magnitude of the change was similar between LEGS and ARMS. Increases in CK and Mb were significantly (P < 0.05) larger after ARMS than LEGS at 72 and 96 h post-exercise. EPT and IPT were significantly (P < 0.05) lower than the baseline up to 96 h post-exercise for ARMS but were fully recovered by 96 h post-exercise for LEGS. Decreases in muscle strength were significantly (p < 0.05) larger following ARMS than LEGS at 48, 72, and 96 h post-exercise for EPT, and from 24 h to 96 h post-exercise for IPT. These results suggest that the magnitude of muscle damage is greater and the recovery of muscle function was slower after eccentric exercise of arm elbow flexors than the knee extensors.

Adult↗
PubMed2006

Hexapod Walking: an expansion to Walknet dealing with leg amputations and force oscillations.

The control of the legs of a walking hexapod is a complex problem as the legs have three joints each, resulting in a total of 18 degrees of freedom. We addressed this problem using a decentralized architecture termed Walknet, which consists of peripheral pattern generators being coordinated through influences acting mainly between neighbouring legs. Both, the coordinating influences and the local control modules (each acting only on one leg), are biologically inspired. This investigation shows that it is possible to adapt this approach to account for additional biological data by (1) changing the structure of the selector net in a biological plausible way (including force as an analog variable), (2) introducing a biologically motivated coordination influence for coactivation between legs and (3) adding a hypothetical influence between hind and front legs. This network of controllers has been tested using a dynamic simulation. It is able to describe (a) the behaviour of animals walking with one or two legs being amputated and (b) force oscillations that occur in a specific experimental situation, the standing legs of a walking animal.

Amputation, Surgical↗
PubMed2002

Thoracic leg motoneurons in the isolated CNS of adult Manduca produce patterned activity in response to pilocarpine, which is distinct from that produced in larvae.

In the hawkmoth, Manduca sexta, thoracic leg motoneurons survive the degeneration of the larval leg muscles to innervate new muscles of the adult legs. The same motoneurons, therefore, participate in the very different modes of terrestrial locomotion that are used by larvae (crawling) and adults (walking). Consequently, changes in locomotor behavior may reflect changes in both the CNS and periphery. The present study was undertaken to determine whether motor patterns produced by the isolated CNS of adult Manduca, in the absence of sensory feedback, would resemble adult specific patterns of coordination. Pilocarpine, which evokes a fictive crawling motor pattern from the isolated larval CNS, also evoked robust patterned activity from leg motoneurons in the isolated adult CNS. As in the larva, levator and depressor motoneurons innervating the same leg were active in antiphase. Unlike fictive crawling, however, bursts of activity in levator or depressor motoneurons of one leg alternated with bursts in the homologous motoneurons innervating the opposite leg of the same segment and the leg on the same side in the adjacent segment. The most common mode of intersegmental activity generated by the isolated adult CNS resembled an alternating tripod gait, which is displayed, albeit infrequently, during walking in intact adult Manduca. A detailed analysis revealed specific differences between the patterned motor activity that is evoked from the isolated adult CNS and activity patterns observed during walking in intact animals, perhaps indicating an important role for sensory feedback. Nevertheless, the basic similarity to adult walking and clear distinctions from the larval fictive crawling pattern suggest that changes within the CNS contribute to alterations in locomotor activity during metamorphosis.

Action Potentials↗
PubMed1984

Intercalary regeneration in legs of crayfish: proximal segments.

An arthropod leg represents a protuberance of the body segmental integument which bears distinctive markers in both the mediolateral and the anteroposterior axes. To clarify the biaxial organization of the body segmental morphogenetic field, and to study the relation among the whole-limb, limb segmental, and body segmental fields previously recognized in arthropods, we have grafted a proximal leg segment into the ventral midline in crayfish. After this operation the majority of animals regenerated a mirror-symmetric pair of supernumerary legs at the host site. Some of these legs had the most proximal segment, the coxa, partially fused to the adjacent body surface. Minority patterns of regeneration included one midline leg with a gill, three midline legs with a gill, and two normal legs with a third double-half leg. These results are compatible with the principle that intercalary regeneration restores the continuity of positional information.

Animals↗
PubMed1991

An improved Horridge procedure for studying leg-position learning in cockroaches.

The Horridge method for studying leg-position learning in insects was modified using an electronic device that eliminates stimulation of the trained leg and differences in positioning the experimental insect with respect to the yoked control. The device allows any conditioning stimulus to be applied to any part of the body contingent on either lifting or lowering a leg, and interfaces with a personal computer to store and analyze data on the percentage of stimulation during each minute, avoidance of stimulation by maintaining a leg position, and escape from stimulation by changing leg position. The device was used to train cockroaches with intact central nervous systems to keep a mesothoracic leg lifted to avoid shock to the prothorax. The performance of the experimental cockroaches was only marginally better than that of yoked controls during training and testing. The effect of leg-lift learning was much more apparent during reversal, however, when the experimental cockroaches kept their legs' lifted and therefore received many more shocks than did the formerly yoked controls.

Animals↗
PubMed1986

Exchange of free fatty acids and glucose in leg tissues before and immediately after surgery.

The present study was undertaken to investigate whether there is an augmented uptake of free fatty acids (FFA) in the leg tissues immediately after surgery when the energy expenditure of the leg is increased considerably. Eight patients were studied before and after cholecystectomy. Blood and plasma flow were determined in one leg, as well as arterio-venous concentration differences for oxygen, glycose, lactate and the total fraction of FFA. To determine uptake and release of FFA, 1-(14C)-oleic acid was infused intravenously and the arterio-venous differences for (14C)-FFA were determined. The mean oxygen uptake in the leg increased from 0.72+/-0.06 mmol/min to 1.78+/-0.41 mmol/min. The uptake of free fatty acids in the leg did not increase significantly after cholecystectomy when compared to before operation in spite of the marked increase in oxygen uptake. Postoperatively there was, however, a positive linear relationship between the uptake of FFA and that of oxygen in the leg. The glucose uptake, after correction for released lactate, corresponded to 7% of the oxygen uptake before surgery and 13% after surgery. The arterial FFA concentration did not change. This study indicates that the combined possible contribution of glucose and free fatty acids to the oxidative energy metabolism of the leg tissues exceeded the oxygen uptake before, but not after surgery. In the postoperative state there was a positive correlation between oxygen uptake and FFA uptake in the leg.

Journal Article↗
PubMed2005

The influence of superficial venous surgery and compression on incompetent calf perforators in chronic venous leg ulceration.

OBJECTIVES: Previous studies have suggested that perforating vein incompetence is reduced by surgery to superficial veins. This study analysed the effect in a randomised clinical trial. DESIGN: Retrospective analysis of duplex data. METHODS: Patients in this study were part of the ESCHAR randomised controlled trial. All patients had chronic venous leg ulceration with superficial venous reflux. Patients were treated with compression bandaging alone or compression plus superficial venous surgery. Legs were assessed using colour venous duplex prior to treatment and at 3 and 12 months. RESULTS: Of 500 patients recruited to the ESCHAR trial, 261 were included in this study. One hundred and forty six of 261 legs were treated with compression alone and 115/261 underwent compression and superficial venous surgery. In the compression group, more legs had incompetent perforators at 12 months (77/131) compared to baseline (61/146, p =0.010, Wilcoxon Signed Ranks test for paired data in 131 legs). Following surgery, significantly fewer legs had incompetent calf perforators (59/115 vs 44/104 at 12 months, p =0.001, Wilcoxon Signed Ranks test for paired data in 104 legs). In addition, significantly fewer legs in the compression and surgery group developed new perforator incompetence in comparison to the group treated with compression alone (12/104 vs 36/131, p =0.003, Chi-Squared test). CONCLUSION: Surgical correction of superficial reflux may abolish incompetence in some calf perforators and offer protection against developing new perforator incompetence.

Bandages↗
PubMed2005

Influence of swing leg movement on running stability.

The aim of this study was to investigate the role of the swing leg movement on running stability. A simple model was used describing a forward hopping motion. The model consisted of two sub-models, namely a spring-mass system for the stance phase and a functional control model for the swing phase (represented by a passive or actively driven pendulum). To verify the main simulation results, an experimental study on treadmill running was performed. The results of the model indicated that for certain running speeds and pendulum lengths, the behavior of the mechanical system was stable. The following characteristic dependencies between the model parameters were observed. (1) Pendulum length and hip muscle activity determined running height and therefore swing duration. (2) Horizontal velocity was inversely related to leg angle of attack. Increased speed corresponded to flatter leg angles at touch-down, which is in agreement with experimental studies and previous predictions of spring-mass running. It was shown that a biologically motivated control approach with oscillating leg movements is well capable of generating stable hopping movements. Due to its simplicity, however, the monopedal model failed to explain more detailed mechanisms like the swing-leg to stance-leg interaction or the functional role of the leg segmentation. This simple model is therefore considered as a functional mechanical template for legged locomotion, which could help to build more elaborate models in the future.

Biomechanical Phenomena↗
PubMed2005

Leg coordination during turning on an extremely narrow substrate in a bug, Mesocerus marginatus (Heteroptera, Coreidae).

The turning movement of a bug, Mesocerus marginatus, is observed when it walks upside-down below a horizontal beam and, at the end of the beam, performs a sharp turn by 180 degrees . The turn at the end of the beam is accomplished in three to five steps, without strong temporal coordination among legs. During the stance, leg endpoints (tarsi) run through rounded trajectories, rotating to the same side in all legs. During certain phases of the turn, a leg is strongly depressed and the tarsus crosses the midline. Swing movements rotate to the same side as do leg endpoints in stance, in strong contrast to the typical swing movements found in turns or straight walk on a flat surface. Terminal location is found after the search through a trajectory that first moves away from the body and then loops back to find substrate. When a leg during stance has crossed the midline, in the following swing movement the leg may move even stronger on the contralateral side, i.e. is stronger depressed, in contrast to swing movements in normal walking, where the leg is elevated. These results suggest that the animals apply a different control strategy compared to walking and turning on a flat surface.

Animals↗
PubMed2004

Spatial and temporal regulation of the homeotic selector gene Antennapedia is required for the establishment of leg identity in Drosophila.

Antennapedia is one of the homeotic selector genes required for specification of segment identity in Drosophila. Dominant mutations that ectopically express Antennapedia cause transformation of antenna to leg. Loss-of-function mutations cause partial transformation of leg to antenna. Here we examine the role of Antennapedia in the establishment of leg identity in light of recent advances in our understanding of antennal development. In Antennapedia mutant clones in the leg disc, Homothorax and Distal-less are coexpressed and act via spineless to transform proximal femur to antenna. Antennapedia is negatively regulated during leg development by Distal-less, spineless, and dachshund and this reduced Antennapedia expression is needed for the proper development of distal leg elements. These findings suggest that the temporal and spatial regulation of the homeotic selector gene Antennapedia in the leg disc is necessary for normal leg development in Drosophila.

Animals↗
PubMed2003

The role of Wg signaling in the patterning of embryonic leg primordium in Drosophila.

Cellular interaction between the proximal and distal domains of the limb plays key roles in proximal-distal patterning. In Drosophila, these domains are established in the embryonic leg imaginal disc as a proximal domain expressing escargot, surrounding the Distal-less expressing distal domain in a circular pattern. The leg imaginal disc is derived from the limb primordium that also gives rise to the wing imaginal disc. We describe here essential roles of Wingless in patterning the leg imaginal disc. Firstly, Wingless signaling is essential for the recruitment of dorsal-proximal, distal, and ventral-proximal leg cells. Wingless requirement in the proximal leg domain appears to be unique to the embryo, since it was previously shown that Wingless signal transduction is not active in the proximal leg domain in larvae. Secondly, downregulation of Wingless signaling in wing disc is essential for its development, suggesting that Wg activity must be downregulated to separate wing and leg discs. In addition, we provide evidence that Dll restricts expression of a proximal leg-specific gene expression. We propose that those embryo-specific functions of Wingless signaling reflect its multiple roles in restricting competence of ectodermal cells to adopt the fate of thoracic appendages.

Animals↗
PubMed2001

Changes in muscle mass, fat mass, and bone mineral content in the legs after stroke: a 1 year prospective study.

Demineralization and muscle atrophy, common among patients with hemiplegia, may be risk factors for future hip fracture. The aim of this longitudinal study was to investigate changes in lean (muscle) mass and bone mineral content (BMC) of the legs during the first year after stroke according to the patient's ambulatory level. Twenty-five patients immobilized due to acute stroke were followed. BMC and lean mass of each leg were measured at a mean of 7 days, 2 months, 7 months, and 1 year after the stroke using dual-energy X-ray absorptiometry. Both BMC and lean mass had decreased significantly in the paretic leg (p < 0.05) at the 1 year evaluation and the loss was significantly greater on the paretic side compared with the nonparetic side (p < 0.001). Patients who had not relearned to walk at the 2 month evaluation (n = 12) lost 6% (p < 0.05) of their lean mass in the paretic leg during this time period, and this mass was not regained within the subsequent 10 months. In contrast, a significant 5% loss of lean mass found at 2 months on the nonparetic side was regained completely. With respect to the patients who relearned to walk within the first 2 months (n = 13) lean mass had increased by 5% after 1 year (p < 0.05) in the nonparetic leg, whereas no significant changes were found in the paretic leg during follow-up. Both groups of patients did, however, lose bone mineral in the paretic leg during the first year after stroke (9% and 6%, respectively, p < 0.05), but only the patients who were still unable to walk by 2 months had significant bone loss in the nonparetic leg also (3%, p < 0.05). Thus, lean muscle mass is rapidly lost and may be regained shortly after stroke, whereas loss of BMC appears difficult to prevent, especially on the paretic side. Regaining muscle mass may, however, slow the loss of bone mineral.

Adipose Tissue↗
PubMed1988

[Diagnosis of deep leg vein thromboses by real-time sonography].

Real-time ultrasonography was performed on both legs of 104 patients with suspected deep-vein thrombosis of the legs. The results were compared with those of phlebography (146 one-extremity phlebograms) independently performed. During the first part of the study (69 individual phlebograms) only the upper leg and popliteal region were assessed: absent compressibility of the vessel lumen was the only criterion of thrombosis. In the second part (77 phlebograms) the lower leg was also investigated: non-compressible, echo-poor vessels were typical of thrombosis. Phlebography demonstrated 21 thromboses of the common femoral vein, 36 of the superficial femoral vein, and 41 of the popliteal vein. The 77 phlebograms in the second part demonstrated 29 thromboses of the deep veins of the lower leg. Sonography had a sensitivity of 100% and a specificity of 99% for the region of the common femoral vein, 95% and 99%, respectively, for the superficial femoral vein, 95% and 99% for the popliteal vein and 89% and 100% for the deep veins of the lower leg. Real-time ultrasonography of the deep-vein system of the leg is thus of great diagnostic value both for the upper and the lower leg and is very useful as the initial physical method of examination if thrombosis is suspected.

Adolescent↗
PubMedDate not supplied

Influence of stochastic events on the phenotypic variation of common white leg markings in the Arabian horse: implications for various genetic disorders in humans.

One method of assessing the influence of stochastic events on phenotypic variation is to study morphological differences in paired limbs of the same individual. These limbs have identical genotypes and similar intra-uterine environments and are analogous to monozygotic twins. Common white leg markings have a multifactorial mode of inheritance in the Arabian horse. Asymmetry occurs frequently for these markings. Using computerized registration records obtained from the Arabian Horse Registry of America, Inc., the types of markings were quantified in the left foreleg and left hind leg of bay and chestnut horses when a specific marking occurred in (1) a paired right leg, (2) both right legs, and (3) both right legs and the other left leg. The variation in the markings in the left legs of these horses is evidence of the role of stochastic events during development. The relatively high frequency of a specific type of asymmetry, with one leg being completely pigmented, is of special biological interest and has implications for various human disorders that are characterized by reduced penetrance and variable expressivity.

Animals↗
PubMed1999

Effects of dietary roxarsone supplementation, lighting program, and season on the incidence of leg abnormalities in broiler chickens.

Two 4 x 2 factorial experiments were designed to test the effects of four diets, differing in anticoccidial programs and roxarsone (3-nitro-4-hydroxyphenylarsonic acid) content, and two lighting programs on the incidence of leg abnormalities in 56-d-old male and female broiler chickens. The four diets were: A) basal diet + salinomycin (60.0 g/ton); B) basal diet + salinomycin (60.0 g/ton) + roxarsone (45.4 g/ton); C) basal diet + roxarsone (45.4 g/ton) + live coccidial vaccine; and D) basal diet + live coccidial vaccine. The light treatments were: 1) restricted (R) [18 h light (L): 6 h dark (D)] and 2) standard (S) [23L:1D]. The respective experiments were conducted during winter (Experiment 1, November to January) and summer (Experiment 2, June to August) growing conditions in the southeastern U.S. Light treatment had no significant (P > 0.10) effect on the incidence of leg abnormalities in either experiment. However, in Experiment 1, there was a light treatment by sex interaction; leg abnormalities were greater for males on Treatment R than Treatment S. In Experiment 2, females had a higher incidence of leg abnormalities than males (8.29 vs 4.73%). There was a diet by sex interaction for the incidence of leg abnormalities in Experiment 2; females had a greater incidence of leg abnormalities than males on Treatment A. In both experiments, the incidence was greater with dietary treatments containing roxarsone (P < 0.10). The percentage of leg abnormalities was greater in Experiment 2 than Experiment 1. Leg abnormalities were primarily due to fibrosis of the gastrocnemius tendons and tendon sheaths.

Animal Feed↗
PubMed1989

Dynamic axial fixation for immobilization of cross-leg flaps in chronic osteomyelitis.

Free flaps are usually the first choice for soft tissue coverage in the distal leg. There continue to be, however, some clinical situations in which a cross-leg flap is the best choice. Use of the cross-leg flap has previously been limited by the difficulty of immobilizing both legs during the early healing stage (2 to 3 weeks). The traditional plaster immobilization or multibar external fixator system is time consuming to apply, difficult to adjust, cumbersome for nursing care, and uncomfortable for the patient. We have used the Orthofix external fixator to immobilize a cross-leg flap in 3 patients with refractory distal tibial osteomyelitis. The Orthofix dynamic axial fixator (DAF) is a single frame external fixator which, when used in a cross-leg fashion, is quick and easy to apply. It provides the necessary strength for immobilization and overhead suspension. It has few parts and is therefore lighter and less awkward both for the patient and nursing personnel and is easy to adjust on the ward or in the clinic. The DAF has two modes: locked (static) and released (dynamic). The locked mode can be easily adjusted to alter tension on the healing flap. As the flap matures the dynamic mode allows the frame to slide, decreasing muscle spasms and increasing flap movement. The DAF also provides better soft tissue access for flap observation and nursing care. Few transfixation pins are needed, decreasing the chance of pin tract infection. When a cross-leg flap is required, use of the DAF for immobilization circumvents many of the previous problems with both-leg immobilization.

Accidents, Traffic↗
PubMed2003

The passive straight leg raising test in the diagnosis and treatment of lumbar disc herniation: a survey of United kingdom osteopathic opinion and clinical practice.

STUDY DESIGN: Postal questionnaire survey. OBJECTIVES: To carry out a confidential postal survey of United Kingdom osteopaths in order to record and assess their use of the passive straight leg raising test in the diagnosis of, and choice of, manipulation for lumbar disc herniation. The study also sought to determine whether an association existed between osteopaths' manipulation of suspected lumbar disc herniation and their use of the straight leg raising test, the length of their working hours, and their use of manipulation for the treatment of other lumbar conditions. SUMMARY OF BACKGROUND DATA: The literature is not agreed on important aspects of the straight leg raising test, or on the use of spinal manipulation for suspected lumbar disc herniation. This is thought to be the first study to investigate opinion and practice in a large group of spinal manipulators, in this case United Kingdom osteopaths. METHODS: A questionnaire was sent to all 1030 United Kingdom osteopaths registered with the General Osteopathic Council in January 2000. It comprised four sections: personal characteristics, professional characteristics, background to low back pain cases, details of straight leg raising test understanding and use within the diagnosis and treatment of lumbar disc herniation. RESULTS: A response rate of 44% was achieved. United Kingdom osteopaths' opinions of low back pain and lumbar disc herniation clinical presentations, details of straight leg raising test mode of action, procedure, and interpretation were in keeping with the literature. Fifty-four percent of respondents sometimes employed manipulation in the treatment of lumbar disc herniation, but most of the others described the practice as "dangerous." The literature is similarly divided on the practice. Chi-square and Cramer V analysis implied that respondents were not influenced in choosing manipulation for lumbar disc herniation by their use of the straight leg raising test (chi2 = 4.002, df = 3, Cramer V = 0.0959, P = 0.261, alpha 0.05, n = 435). A moderate association implied that the frequency of use of such manipulation for all lumbar conditions influenced the choice of that treatment for lumbar disc herniation (chi2 = 81.808, df = 4, Cramer V = 0.4302, P < 0.001, alpha = 0.05, n = 442). There was also a weak association suggesting that hours worked per week influenced the choice of manipulation for lumbar disc herniation (chi2 = 9.840, df = 3, Cramer V = 0.1499, P = 0.020, alpha = 0.05, n = 438). CONCLUSIONS: Respondents to this survey frequently treated low back pain and often employed the straight leg raising test in its diagnosis. Their recognition of the clinical presentation of lumbar disc herniation and their use and understanding of the straight leg raising test were in keeping with the literature. Respondents were divided nearly equally between those who would expect patient benefit from the use of manipulation for lumbar disc herniation and those who criticized the practice. There is a need for further research into the clinical reasoning employed for the manipulative treatment of lumbar disc herniation.

Attitude of Health Personnel↗
PubMed2005

Directionally compliant legs influence the intrinsic pitch behaviour of a trotting quadruped.

Limb design is well conserved among quadrupeds, notably, the knees point forward (i.e. cranial inclination of femora) and the elbows point back (i.e. caudal inclination of humeri). This study was undertaken to examine the effects of joint orientation on individual leg forces and centre of mass dynamics. Steady-speed trotting was simulated in two quadrupedal models. Model I had the knee and elbow orientation of a quadruped and model II had a reversed leg configuration in which knees point back and elbows point forward. The model's legs showed directional compliance determined by the orientation of the knee/elbow. In both models, forward pointing knees/elbows produced a propulsive force bias, while rearward pointing knees/elbows produced a braking force bias. Hence, model I showed the same pattern of hind-leg propulsion and fore-leg braking observed in trotting animals. Simulations revealed minimal pitch oscillations during steady-speed trotting of model I, but substantially greater and more irregular pitch oscillations of model II. The reduced pitch oscillation of model I was a result of fore-leg and hind-leg forces that reduced pitching moments during early and late stance, respectively. This passive mechanism for reducing pitch oscillations was an emergent property of directionally compliant legs with the fore-hind configuration of model I. Such intrinsic stability resulting from mechanical design can simplify control tasks and lead to more robust running machines.

Animals↗