Atrophy of hip abductor muscles is related to clinical severity in a hip osteoarthritis population

Osteoarthritis mainly affects weight‐bearing joints such as the hip and knee and is the most common form of arthritis. Greater muscle atrophy with fatty infiltration of gluteal muscles and decreased hip abduction strength has previously been identified with increasing severity of radiological hip OA. However, it is well documented that radiographic findings of OA do not always correlate with clinical severity. The aim of this secondary analysis was to examine whether atrophy and strength of gluteus maximus (GMax), medius (GMed), minimus (GMin), and tensor fascia lata (TFL) is associated with the clinical severity of OA. Twenty participants with unilateral hip OA and 20 age‐ and sex‐matched asymptomatic controls were classified on the basis of clinical severity (mild, moderate‐severe and asymptomatic groups) using the Oxford hip score. Muscle volumes of GMax, GMed, GMin, and TFL were determined using magnetic resonance imaging and expressed as asymmetry between limbs. A hand‐held dynamometer was used to identify hip rotation and abduction strength. Regression analyzes were used to identify the association between muscle asymmetry and patient‐reported severity of hip OA. Both symptomatic groups (mild and moderate‐severe) demonstrated significant asymmetry in GMax (P < 0.01) and GMin (P < 0.01). GMed asymmetry was associated with only the moderate‐severe symptomatic group. Hip abduction strength was reduced in both symptomatic groups. Gluteal muscle atrophy was associated with the clinical severity of OA. Clinical severity could be a useful tool for clinicians interpreting likely gluteal muscle changes and planning rehabilitation strategies for hip OA patients. Clin. Anat. 31:507–513, 2018. © 2018 Wiley Periodicals, Inc.     

Relationships between early postoperative gait biomechanical factors and patient-reported outcome measures 6 months after total knee arthroplasty

BackgroundThis study was focused on the gait parameters of the knee extensor and hip abductor muscle groups, which are believed to contribute to knee joint function improvement in early postoperative TKA. The associations between patient-reported outcome measures (PROMs) 6 months after total knee arthroplasty (TKA) and the early postoperative internal knee extension moment, knee extension negative joint power, and internal hip abduction moment while walking were investigated.MethodsTwenty-one patients who underwent primary TKA for knee osteoarthritis were included. Three weeks after TKA, gait at a comfortable speed was measured by three-dimensional motion analysis. The lower limb joint angle, internal joint moment, and joint power parameters on the operated side while standing were calculated. The PROMs 6 months after TKA were assessed using the Japanese Knee Osteoarthritis Measure (JKOM). The relationship between each gait biomechanical parameter and the JKOM was determined.ResultsThe maximum internal knee extension moment and maximum knee extension negative joint power during the early stance showed moderate negative correlations with the JKOM scores. The maximum internal hip abduction moment was not correlated with the JKOM scores. The maximum internal hip extension moment during the early stance and internal hip flexion moment during the late stance showed moderate negative correlations with the total JKOM scores.ConclusionThe early postoperative internal knee extension moment, maximum knee extension negative joint power, and internal hip extension and flexion moment are associated with patient PROMs 6 months after TKA.     

Does increasing step width alter knee biomechanics in medial compartment knee osteoarthritis patients during stair descent?

BackgroundResearch shows that one of the first complaints from knee osteoarthritis (OA) patients is difficulty in stair ambulation due to knee pain. Increased step width (SW) has been shown to reduce first and second peak internal knee abduction moments, a surrogate variable for medial compartment knee joint loading, during stair descent in healthy older adults. This study investigates the effects of increased step width (SW) on knee biomechanics and knee pain in medial compartment knee OA patients during stair descent.MethodsThirteen medial compartment knee OA patients were recruited for the study. A motion analysis system was used to obtain three-dimensional joint kinematics. An instrumented staircase was used to collect ground reaction forces (GRF). Participants performed stair descent trials at their self-selected speed using preferred, wide, and wider SW. Participants rated their knee pain levels after each SW condition.ResultsIncreased SW had no effect on peak knee abduction moments and knee pain. Patients reported low levels of knee pain during all stair descent trials. The 2nd peak knee adduction angle and frontal plane GRF at time of 2nd peak abduction moment were reduced with increasing SW.ConclusionsThe findings suggest that increases in SW may not influence knee loads in medial compartment knee OA patients afflicted with low levels of knee pain during stair descent.     

Treatment of internal rotation gait due to gluteus medius and minimus overactivity in cerebral palsy: Anatomical rationale of a new surgical procedure and preliminary results in twelve hips

Spastic overactivity of the anterior fibers of the gluteus medius and minimus can result in an internal rotation gait associated with excessive hip and pelvic rotation. The currently advocated operation for this problem can result in weakness of hip abduction. The anatomical features of the gluteal muscles suggest that this gait abnormality can be corrected by selectively reducing the internal rotator function of the anterior fibers of the glutei without disturbing the abductor fibers. Such an operative procedure was devised and performed on 12 hips. The gait improved in all hips without any demonstrable weakness of the hip abductor power. Clin. Anat. 11:22–28, 1998. © 1998 Wiley-Liss, Inc.     

Contributions of muscles and external forces to medial knee load reduction due to osteoarthritis braces

BackgroundBraces for medial knee osteoarthritis can reduce medial joint loads through a combination of three mechanisms: application of an external brace abduction moment, alteration of gait dynamics, and reduced activation of antagonistic muscles. Although the effect of knee bracing has been reported independently for each of these parameters, no previous study has quantified their relative contributions to reducing medial knee loads.MethodsIn this study, we used a detailed musculoskeletal model to investigate immediate changes in medial and lateral loads caused by two different knee braces: OA Assist and OA Adjuster 3 (DJO Global). Seventeen osteoarthritis subjects and eighteen healthy controls performed overground gait trials in unbraced and braced conditions.ResultsAcross all subjects, bracing reduced medial loads by 0.1 to 0.3 times bodyweight (BW), or roughly 10%, and increased lateral loads by 0.03 to 0.2 BW. Changes in gait kinematics due to bracing were subtle, and had little effect on medial and lateral joint loads. The knee adduction moment was unaltered unless the brace moment was included in its computation. Only one muscle, biceps femoris, showed a significant change in EMG with bracing, but this did not contribute to altered peak medial contact loads.ConclusionsKnee braces reduced medial tibiofemoral loads primarily by applying a direct, and substantial, abduction moment to each subject's knee. To further enhance brace effectiveness, future brace designs should seek to enhance the magnitude of this unloader moment, and possibly exploit additional kinematic or neuromuscular gait modifications.     

Muscle moment arms of pelvic limb muscles of the ostrich (Struthio camelus)

Muscle moment arms were measured for major muscles of the pelvic limb of the ostrich (Struthio camelus) in order to assess specific functional behaviour and to apply this to locomotor performance. Pelvic limbs of six juvenile ostriches were used for this study. The tendon travel technique was used to measure moment arms of 21 muscles at the hip, knee, ankle and metatarsophalangeal joints throughout the ranges of motion observed during level running. Six of the 21 muscles measured were found to have moment arms that did not change with joint angle, whilst the remainder all demonstrated angle-dependent changes for at least one of the joints crossed. Moment arm lengths tended to be longest for the large proximal muscles, whilst the largest relative changes were found for the moment arms of the distal muscles. For muscles where moment arm varied with joint angle: all hip muscles were found to have increasing moment arms with extension of the joint, knee flexors were found to have moment arms that increased with extension, knee extensor moment arms were found to increase with flexion and ankle extensor moment arms increased with extension. The greatest relative changes were observed in the flexors of the metatarsophalangeal joint, for which a three-fold increase in moment arm was observed from flexion to full extension. Changes in muscle moment arm through the range of motion studied appear to optimize muscle function during stance phase, increasing the effective mechanical advantage of these muscles.     

Evaluation of the walking pattern in two types of patients with anterior cruciate ligament deficiency: copers and non-copers

The purpose of the present study was to investigate whether different walking patterns in healthy subjects and in coper and non-coper subjects with deficient anterior cruciate ligaments could be quantified. An inverse dynamics approach was used to calculate joint kinematics and kinetics for flexion and extension. EMG signals of the hamstrings and quadriceps muscles were recorded. The results showed that the peak knee flexion angle was greater in the copers than in the controls. There was a positive correlation between the peak knee extensor moment and peak knee flexion angle. Furthermore, at a given peak knee flexion angle, the peak knee extensor moment was significantly larger in the controls than in the non-copers. The hip extensor moment in the copers was significantly larger than that of the non-copers and the controls. In conclusion, the three groups walked according to different patterns. It is suggested that the copers stabilized their knee joint by co-contraction of the hamstrings and quadriceps muscles, while the non-copers lacked this ability. Instead, the non-copers reduced the knee extensor moment in order to decrease anterior displacement of the tibia. The walking pattern differences observed between the copers and non-copers may explain their different post-injury activity levels. Electronic Publication     

膝骨关节炎与膝关节伸、屈肌群肌力的相关性研究

目的通过研究膝骨关节炎(knee osteoarthritis,KOA)症状及病变阶段与膝关节伸、屈肌群肌力的相关性,探讨KOA患者肌力训练的关键肌群。方法社区募集健康老年人、单膝KOA患者、双膝KOA患者共99位志愿者,应用膝关节等速肌力测试、WOMAC评分、6 min步行测试、CS-30测试,分析志愿者膝关节伸、屈肌群峰力矩与KOA症状、全身有氧运动能力、关节功能等的相关性。结果单膝KOA组患者患侧膝关节伸肌群等速峰力矩显著低于健侧。双膝KOA组患者症状严重侧和症状较轻侧膝关节伸、屈肌群等速峰力矩差异均有统计学意义。双膝KOA组患者膝关节伸肌群等速峰力矩显著低于健康组。KOA患者膝关节伸、屈肌群等速峰力矩与CS-30测试、6 min步行测试均呈正相关,均与年龄呈负相关;膝关节伸肌群等速峰力矩与WOMAC评分的疼痛和功能障碍项呈负相关。结论膝关节伸、屈肌群均与KOA相关,KOA康复过程中不仅需重视股四头肌等伸肌群的训练,而且要兼顾腘绳肌、腓肠肌等屈肌群的训练。     

Task-specific initial impact phase adjustments in lateral jumps and lateral landings

Load-dependant adjustments in lateral jumps are thought to rely on foot placement and on upper leg’s kinematic and neuromuscular adaptations. The aim of this study was to elucidate task-specific adjustments during the initial impact phase under varying stretch-loads by the comparison of lateral jumps and lateral landings. Ten subjects performed lateral jumps and landings from four distances. Electromyographic (EMG) data of five lower extremity muscles were measured, whilst lower extremity kinematics and kinetics were analysed by 3D motion analysis. Lateral jumps were characterized by increased impact forces, higher lower extremity joint moments with exception of the initial knee abduction moment, greater sagittal knee and hip joint displacements, and a further exorotated foot placement. In lateral landings frontal ankle and hip joint displacements were greater. Thigh muscle and m. tibialis anterior (TA) pre-activity as well as initial post-impact EMG were higher in lateral jumps than in lateral landings, whilst during the reflex-induced phase thigh and shank muscle EMG, except for TA, were enhanced in lateral jumps. From these findings it can be concluded that task specificity in lateral jumps in contrast to lateral landings impedes a stretch-load adequate modulation of initial impact forces which particularly affects ankle joint loading. Foot placement seems to play a decisive role for limiting lateral ankle and medial knee joint loading. Therefore, in sports containing high-impact frontal plane movements a special emphasis in training routines should be paid to foot placement strategy in those movements. Such training interventions might contribute to injury prevention in lateral movements.     

Functional specialisation of the pelvic limb of the hare (Lepus europeus)

We provide quantitative anatomical data on the muscle-tendon architecture of the hare pelvic limb (specifically muscle mass, fascicle length, pennation angle, tendon mass and length). In addition, moment arms of major pelvic limb muscles were measured. Maximum isometric force and power of muscles, the moment of force about a joint, and tendon stress and strain were estimated. Data are compared with published data for other cursorial mammals such as the horse and dog, and a non-specialised Lagamorph, the rabbit. The pelvic limb of the hare was found to contain substantial amounts of hip extensor and adductor/abductor muscle volume, which is likely to be required for power production and stability during rapid turning. A proximal to distal reduction in muscle volume and fascicle length was also observed, as is the case in other cursorial quadrupeds, along with a reduction in distal limb mass via the replacement of muscle volume by long distal limb tendons, capable of storing large amounts of elastic energy. The majority of hare pelvic limb muscle moment arms varied with joint position, giving the hare the capacity to vary muscle function with limb posture and presumably different locomotor activities.     

Gait analysis before or after varus osteotomy of the femur for hip osteoarthritis

SUMMARY OF BACKGROUND: Intertrochanteric varus osteotomy of the femur for hip osteoarthritis is expected to bring improved congruity and increased weight-bearing surface area of the hip joint. Before surgery, we usually make a tracing on a paper using an anteroposterior roentgenogram of the hip to simulate the operating procedures and obtain better conditions in the hip. Nevertheless, there have been some cases in which this procedure does not provide satisfactory postoperative results in terms of relief of pain or locomotion, with long-term limp due to weakness of the hip abductor muscle group and shortening of the leg. OBJECTIVES: To confirm if the improved congruity and increased covering of the weight-bearing surface area obtained by varus osteotomy can be actually reproduced during walking, and to evaluate the kinetic mechanism of the effects of this procedure using gait analysis. METHODS: We measured the strength ratio of the hip abductor muscles as the percent of the opposite side, and analyzed the pelvic movement and data of dynamic electromyography (EMG) recorded during locomotion in 24 female patients who underwent unilateral intertrochanteric varus osteotomy of the femur for hip osteoarthritis, 30 non-surgically-treated female patients with hip osteoarthritis, and 54 healthy women. In the operated patients, the roentgenograms obtained during one-legged stance on the affected side disclosed that 10 were positive for Trendelenburg's phenomenon (T(+) group) and 14 were negative for Trendelenburg's phenomenon (T(-) group). All subjects walked with bare feet at a comfortable pace on a walkway containing a force plate. Photo switches were placed in a walkway to measure the gait velocity and to determine the stance phase time of one gait cycle. Frontal and sagittal trajectories of body surface markers for computerized joint-angle motion analysis were acquired using the Quick-MAG system. EMG data for the gluteus maximus, gluteus medius, tensor fascia latae, and lateral hamstrings recorded using surface electrodes were integrated to quantify as the percent of maximum voluntary contraction (% MVC). RESULTS: This study disclosed that the stance phase time was shorter and the strength ratio of the hip abductor muscles was lower in the operated patients than those in the other 2 groups, and the change of the pelvic obliquity was smaller and the % MVC of the gluteus medius and tensor fascia latae were greater than those in the normal subjects. The change of the pelvic tilt showed the same pattern with those of the pelvic obliquity. The T(+) group showed decreased strength ratio of the hip abductor muscles and increased % MVC for the gluteus medius and the tensor fascia latae compared to the T(-) group, but the changes of both the pelvic obliquity and pelvic tilt did not significantly differ in the 2 groups. CONCLUSION: This study showed the postoperative reappearance of the simulated conditions in the hip before varus osteotomy of the femur, providing evidence that the pelvis was horizontally maintained during walking due to decreased stance phase time and increased performance of the hip abductor muscles after this procedure.     

髋外展肌疲劳对不同性别人群单腿侧跳落地时神经肌肉控制的影响

目的 比较髋外展肌疲劳对不同性别人群单腿侧跳落地期间的姿势稳定性及其神经肌肉控制的影响。方法 比较20名男性和20名女性在髋外展肌疲劳干预前后进行单腿侧跳落地期间的压力中心(center of pressure, COP)、地面反作用力(ground reaction force, GRF)、下肢运动学、关节力矩、肌肉活动度等。结果 疲劳后,男性和女性COP在冠状面的最大位移和平均速度增加,髋关节外展峰值角度和踝关节外翻峰值角度增加,踝关节内翻峰值力矩增加。触地前200 ms,男性股直肌、股二头肌、胫前肌、腓骨长肌的激活小于女性;触地后200 ms,男性股二头肌激活小于女性。结论 髋外展肌疲劳导致冠状面姿势稳定性下降,髋、踝关节冠状面稳定性下降,可能增加关节损伤风险。不同性别人群的姿势调控策略存在差异,提示下肢关节损伤机制的性别差异值得进一步探究。     

Effects of increased step width on frontal plane knee biomechanics in healthy older adults during stair descent

BackgroundPeak internal knee abduction moment is a common surrogate variable associated with medial compartment knee loading. Stair descent has been shown to yield a greater peak knee abduction moment compared to level-walking. Changes in step width (SW) may lead to changes in frontal plane lower extremity limb alignment in the frontal plane and alter peak knee abduction moment. The purpose of this study was to investigate the effects of increased SW on frontal plane knee biomechanics during stair descent in healthy older adults.MethodsTwenty healthy adults were recruited for the study. A motion analysis system was used to obtain three-dimensional lower limb kinematics during testing. An instrumented 3-step staircase with two additional customized wooden steps was used to collect ground reaction forces (GRF) data during stair descent trials. Participants performed five stair descent trials at their self-selected speed using preferred, wide (26% leg length), and wider (39% leg length) SW.ResultsThe preferred normalized SW in older adults during stair descent was 20% of leg length. Wide and wider SW during stair descent reduced both first and second peak knee adduction angles and abduction moments compared to preferred SW in healthy adults.ConclusionsIncreased SW reduced peak knee adduction angles and abduction moments. The reductions in knee abduction moments may have implications in reducing medial compartment knee loads during stair descent.     

Hip muscle atrophy in patients with acetabular labral joint pathology

Intra-articular hip joint pathology is a source of hip and groin pain in active individuals and is thought to be a precursor to hip osteoarthritis. Limited evidence exists to guide appropriate physiotherapy management for these patients. Identification of which hip muscles are affected may help clinicians to develop effective exercise programs. A cross-sectional observational study in a hospital setting was conducted to investigate the size of individual hip abductor, hip extensor, and hip external rotator muscles in patients with acetabular labral joint pathology compared with age and sex matched healthy subjects. Twelve participants (eight females, four males), aged 20–53 years, with a medical diagnosis of unilateral acetabular labral tear and 12 healthy participants were recruited. Magnetic resonance imaging was used to assess cross-sectional areas of the gluteus minimus, gluteus medius, upper gluteus maximus, lower gluteus maximus, piriformis, and quadratus femoris muscles bilaterally. Gluteus medius muscle cross-sectional area was significantly different between groups (P < 0.01, effect size = 0.92) with muscle size found to be smaller in the pathology group. No differences were found for the other hip muscles (P > 0.05). These findings suggest that hip muscles are not all affected equally by the presence of intra-articular hip joint pathology. Atrophy of specific hip muscles, which are important in hip joint and pelvic stability, may alter hip joint function during gait and functional tasks. Clinicians treating patients with intra-articular hip joint pathology may need to prescribe exercises targeting the specific muscles with demonstrated dysfunction. Clin. Anat. 33:538–544, 2020. © 2019 Wiley Periodicals, Inc.     

Relationships between Isometric Muscle Strength,Gait Parameters,and Gross Motor Function Measure in Patients with Cerebral Palsy

PurposeThis study investigated the correlation between isometric muscle strength, gross motor function, and gait parameters in patients with spastic cerebral palsy and to find which muscle groups play an important role for gait pattern in a flexed knee gait.ResultsPeak isometric muscle strength of all muscle groups was not related to the GMFM score and the gross motor function classification system level. Peak isometric strength of the hip extensor and knee extensor was significantly correlated with the mean pelvic tilt (r=-0.588, p=0.003 and r=-0.436, p=0.033) and maximum pelvic obliquity (r=-0.450, p=0.031 and r=-0.419, p=0.041). There were significant correlations between peak isometric strength of the knee extensor and peak knee extensor moment in early stance (r=0.467, p=0.021) and in terminal stance (r=0.416, p=0.043).ConclusionThere is no correlation between muscle strength and gross motor function. However, this study showed that muscle strength, especially of the extensor muscle group of the hip and knee joints, might play a critical role in gait by stabilizing pelvic motion and decreasing energy consumption in a flexed knee gait.     

Isokinetic assessment of the hip muscles in patients with osteoarthritis of the knee

OBJECTIVES:

To evaluate the difference in isokinetic strength of hip muscles between patients with knee osteoarthritis (OA) and matched healthy controls, and to establish the correlation between this isokinetic strength and pain and function in patients with knee OA.

METHODS:

25 patients with a diagnosis of unilateral knee OA, 25 patients with bilateral knee OA, and 50 matched controls were evaluated using the visual analog scale for pain, knee Lequesne index, Western Ontario and McMaster Universities questionnaire and an isokinetic test.

RESULTS:

The groups were matched for age, gender and body mass index. The results of the isokinetic test revealed lower peak torque of the hip in patients with OA of the knee than in the control group for all movements studied. Strong correlations were found between the peak torque, visual analog scale and function.

CONCLUSIONS:

Patients with OA of the knee exhibit lower isokinetic strength in the hip muscles than healthy control subjects. Strengthening the muscles surrounding the hip joint may help to decrease pain in people with knee OA. Some correlations between pain/function and peak torque were found.     

Computational modelling of locomotor muscle moment arms in the basal dinosaur Lesothosaurus diagnosticus: assessing convergence between birds and basal ornithischians

Ornithischia (the 'bird-hipped' dinosaurs) encompasses bipedal, facultative quadrupedal and quadrupedal taxa. Primitive ornithischians were small bipeds, but large body size and obligate quadrupedality evolved independently in all major ornithischian lineages. Numerous pelvic and hind limb features distinguish ornithischians from the majority of other non-avian dinosaurs. However, some of these features, notably a retroverted pubis and elongate iliac preacetabular process, appeared convergently in maniraptoran theropods, and were inherited by their avian descendants. During maniraptoran/avian evolution these pelvic modifications led to significant changes in the functions of associated muscles, involving alterations to the moment arms and the activation patterns of pelvic musculature. However, the functions of these features in ornithischians and their influence on locomotion have not been tested and remain poorly understood. Here, we provide quantitative tests of bipedal ornithischian muscle function using computational modelling to estimate 3D hind limb moment arms for the most complete basal ornithischian, Lesothosaurus diagnosticus. This approach enables sensitivity analyses to be carried out to explore the effects of uncertainties in muscle reconstructions of extinct taxa, and allows direct comparisons to be made with similarly constructed models of other bipedal dinosaurs. This analysis supports some previously proposed qualitative inferences of muscle function in basal ornithischians. However, more importantly, this work highlights ambiguities in the roles of certain muscles, notably those inserting close to the hip joint. Comparative analysis reveals that moment arm polarities and magnitudes in Lesothosaurus, basal tetanuran theropods and the extant ostrich are generally similar. However, several key differences are identified, most significantly in comparisons between the moment arms of muscles associated with convergent osteological features in ornithischians and birds. Craniad migration of the iliofemoralis group muscles in birds correlates with increased leverage and use of medial femoral rotation to counter stance phase adduction moments at the hip. In Lesothosaurus the iliofemoralis group maintains significantly higher moment arms for abduction, consistent with the hip abduction mode of lateral limb support hypothesized for basal dinosaurs. Sensitivity analysis highlights ambiguity in the role of musculature associated with the retroverted pubis (puboischiofemoralis externus group) in ornithischians. However, it seems likely that this musculature may have predominantly functioned similarly to homologous muscles in extant birds, activating during the swing phase to adduct the lower limb through lateral rotation of the femur. Overall the results suggest that locomotor muscle leverage in Lesothosaurus (and by inference basal ornithischians in general) was more similar to that of other non-avian dinosaurs than the ostrich, representing what was probably the basal dinosaur condition. This work thereby contradicts previous hypotheses of ornithischian-bird functional convergence.     

Task specificity in the control of intrinsic trunk muscles in man

The human trunk is a complex mechanical system comprised of large and small segments interconnected with several layers of muscles. An accurate control of this system is important during a variety of everyday tasks such as voluntary movements of the trunk, walking and running. This study was designed to investigate the interaction between muscles controlling the pelvis and the trunk during a variety of movements requiring a finely tuned coordination. Four subjects carried out seven different forms of fast oscillatory movements of the pelvis and trunk in the sagittal and transverse planes. Electromyographical activity (EMG) was recorded with surface electrodes from the abdominal muscles rectus abdominis (RA), obliquus externus (OE), obliquus internus (OI), and erector spinae (ES), from the hip flexor muscle rectus femoris (RF), the hip extensor muscle gluteus maximus (GM) and from the hip extensor/knee flexor muscles of the hamstrings group (HAM). Movements were recorded with an optoelectronic system (Selspot). The results indicate that during spontaneous flexion-extension movements of the trunk there was a basic alternating activation between a pure flexor (RF-RA-OE-OI) and an extensor synergy (ES-GM-HAM). Different mixed synergies appeared when more specific patterns of coordination of the pelvis and spine were performed. For example, during pelvic tilts in the sagittal plane, RA-OE-OI-GM formed a synergy which was activated reciprocally with ES. The neural circuitry controlling muscles of the pelvis and trunk is apparently adaptable to a variety of different tasks. Individual muscles were shown to either cause, brake or prevent a movement and to be integrated in several different task-specific motor synergies.(ABSTRACT TRUNCATED AT 250 WORDS)     

Functional anatomy and muscle moment arms of the pelvic limb of an elite sprinting athlete: the racing greyhound (Canis familiaris)

We provide quantitative anatomical data on the muscle-tendon architecture and geometry of the pelvic limb of an elite sprint athlete, the racing greyhound. Specifically, muscle masses, muscle lengths, fascicle lengths, pennation angles and muscle moment arms were measured. Maximum isometric force and power of muscles, the maximum muscle torque at joints and tendon stress and strain were estimated. We compare data with that published for a generalized breed of canid, and other cursorial mammals such as the horse and hare. The pelvic limb of the racing greyhound had a relatively large volume of hip extensor muscle, which is likely to be required for power production. Per unit body mass, some pelvic limb muscles were relatively larger than those in less specialized canines, and many hip extensor muscles had longer fascicle lengths. It was estimated that substantial extensor moments could be created about the tarsus and hip of the greyhound allowing high power output and potential for rapid acceleration. The racing greyhound hence possesses substantial specializations for enhanced sprint performance.