Distribution of Heterogenic Reflexes Among the Quadriceps and Triceps Surae Muscles of the Cat Hind Limb

Wilmink, Ronnie J. H.; Nichols, T. Richard

doi:10.1152/jn.00833.2002

Cited by 68 publications

(80 citation statements)

References 63 publications

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“…Stretch of the hip flexor iliopsoas, representative of a negative θ 1 perturbation, has been reported to reduce ankle extensor activity during gait (Hiebert et al, 1996), equivalent to a positive torque at the distal joint as predicted by the optimal controller. Group I feedback from vasti to soleus, which would contribute to k B (3,2), has been measured (Eccles, Eccles & Lundberg, 1957a), although feedback from vasti to gastrocnemius (contributing to both k R,B (3,2) and k R,B (2,2)) is inhibitory (Wilmink & Nichols, 2003). Length changes in soleus have little or no effect on vastus force generation (k R,B (2,3), (Wilmink & Nichols, 2003), which suggests that, in the cat, k R (3,2) would be greater than k R (2,3), as predicted by the optimal control model.…”

Section: Discussionmentioning

confidence: 99%

“…Group I feedback from vasti to soleus, which would contribute to k B (3,2), has been measured (Eccles, Eccles & Lundberg, 1957a), although feedback from vasti to gastrocnemius (contributing to both k R,B (3,2) and k R,B (2,2)) is inhibitory (Wilmink & Nichols, 2003). Length changes in soleus have little or no effect on vastus force generation (k R,B (2,3), (Wilmink & Nichols, 2003), which suggests that, in the cat, k R (3,2) would be greater than k R (2,3), as predicted by the optimal control model. EU also contains a strongly asymmetric relationship between proximal and distal joints.…”

Section: Discussionmentioning

confidence: 99%

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Asymmetric interjoint feedback contributes to postural control of redundant multi-link systems

2007

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Maintaining the postural configuration of a limb such as an arm or leg is a fundamental neural control task that involves the coordination of multiple linked body segments. Biological systems are known to use a complex network of inter-and intra-joint feedback mechanisms arising from muscles, spinal reflexes, and higher neuronal structures to stabilize the limbs. While previous work has shown that a small amount of asymmetric heterogenic feedback contributes to the behavior of these systems, a satisfactory functional explanation for this nonconservative feedback structure has not been put forth. We hypothesized that an asymmetric multi-joint control strategy would confer both an energetic and stability advantage in maintaining endpoint position of a kinematically redundant system. We tested this hypothesis by using optimal control models incorporating symmetric versus asymmetric feedback with the goal of maintaining the endpoint location of a kinematically redundant, planar limb. Asymmetric feedback improved endpoint control performance of the limb by 16%, reduced energetic cost by 21% and increased interjoint coordination by 40% compared to the symmetric feedback system. The overall effect of the asymmetry was that proximal joint motion resulted in greater torque generation at distal joints than vice versa. The asymmetric organization is consistent with heterogenic stretch reflex gains measured experimentally. We conclude that asymmetric feedback has a functionally relevant role in coordinating redundant degrees of freedom to maintain the position of the hand or foot.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Asymmetric interjoint feedback contributes to postural control of redundant multi-link systems

2007

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“…Evidence for the link between reflex excitability under isometric conditions and its function during movement has been provided by a number of studies. In the feline model, the excitatory heteronymous coupling between the vastii and triceps surae, as well as the inhibitory coupling between the vastii and rectus femoris (Wilmink and Nichols 2003), reflect the in-phase movement of the ankle and knee and the independent movement of the hip during locomotion. In humans, Hreflex amplitude in the soleus is facilitated during hip extension and inhibited during hip flexion reflecting its level of activity in stance and swing phase, respectively (Knikou and Rymer 2002).…”

Section: Functional Implicationsmentioning

confidence: 99%

Stretch reflex coupling between the hip and knee: implications for impaired gait following stroke

2008

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Individuals with hemiparetic stroke often exhibit an abnormal coupling between the frontal plane of the hip and saggital plane of the knee during gait. The purpose of this study was to determine if stretch sensitive reflexes, which are known to be altered following stroke, exhibit similar coupling between the muscles of the hip and knee in the post-stroke population. Eighteen subjects were recruited for this study including ten with hemiparesis resulting from stroke and eight unimpaired, age-matched controls. A servomotor was used to apply ramp and hold perturbations to both the hip and knee joints in separate sessions and electromyographic activity was recorded in eight muscles of the lower limb. Hip abduction perturbations elicited abnormal activation in rectus femoris (RF) in seven of ten stroke subjects with amplitudes ranging from 3.2 to 12.5% of the maximum voluntary contraction (MVC). Only two of eight control subjects exhibited any activity in RF and these responses were only 2.1 and 2.7% of MVC. To determine if the responses in the stroke group were a result of muscle stretch, a musculoskeletal model was used to simulate the experimental abduction perturbations and estimate muscle length changes. The simulation revealed that RF should be shortened by the perturbations and this suggests that the response was not likely due to direct stretch. Moreover, knee flexion perturbations elicited responses in the hip adductors (AL) with a mean amplitude of 5.1 ± 3.8% of MVC across all stroke subjects while no significant responses were recorded in controls. The presence of a reciprocal, reflex-mediated coupling between RF and AL following stroke suggests

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“…These reflex mechanisms, called ''length feedback'' and ''force feedback,'' result from neural signals generated by muscle receptors that project back to the muscle of origin as well as other muscles. 102 Signals generated by muscle stretch are called length feedback and those generated by muscle force are called force feedback. Length feedback, which occurs around the same timeframe as the stretch reflex, links muscles that are synergists through excitatory feedback and those with opposite actions by reciprocal inhibition.…”

Section: Loading Phasementioning

confidence: 99%

“…67 Length feedback also links monoarticular muscles, like the vastus lateralis and soleus, with excitatory feedback. 102 Force feedback, which is provided by stimulation of the Golgi tendon organ, connects muscles that cross different joints and exert torque in different directions through inhibitory feedback. 67 Length feedback contributes to joint stiffness, while force feedback regulates coupling between joints.…”

Section: Loading Phasementioning

confidence: 99%

Plyometric Exercise in the Rehabilitation of Athletes: Physiological Responses and Clinical Application

Chmielewski¹,

Myer²,

Kauffman³

et al. 2006

J Orthop Sports Phys Ther

109

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Plyometric exercise was initially utilized to enhance sport performance and is more recently being used in the rehabilitation of injured athletes to help in the preparation for a return to sport participation. The identifying feature of plyometric exercise is a lengthening of the muscle-tendon unit followed directly by shortening (stretch-shortening cycle). Numerous plyometric exercises with varied difficulty and demand on the musculoskeletal system can be implemented in rehabilitation. Plyometric exercises are initiated at a lower intensity and progressed to more difficult, higher intensity levels. The progression to higher-intensity plyometric exercise is thought to resolve postinjury neuromuscular impairments and to prepare the musculoskeletal system for rapid movements and high forces that may be similar to the demands imposed during sport participation, thus assisting the athlete with a return to full function. While there is a large body of scientific literature that supports the use of plyometric exercise to enhance athletic performance, evidence is sparse regarding the effectiveness of plyometric exercise in promoting a quick and safe return to sport after injury. This review will describe the mechanisms involved in plyometric exercise, discuss the considerations for implementing plyometric exercise into rehabilitation protocols, examine the evidence supporting the use of plyometric exercises, and make recommendations for future research. J Orthop Sports Phys Ther 2006;36(5):308-319. doi:10.2519/ jospt.2006.2013 Key Words: jump training, neuromuscular, return to sport, stretch shortening P lyometric exercise is a popular form of training commonly used to improve athletic performance. 18 The stretchshortening cycle, which involves stretch of the muscle-tendon unit immediately followed by shortening, is integral to plyometric exercise. The stretch-shortening cycle enhances the ability of the muscle-tendon unit to produce maximal force in the shortest amount of time, 3,82 prompting the use of plyometric exercise as a bridge between pure strength and sports-related speed.22 Maximaleffort plyometric training, or ''shock training,'' was first introduced to Russian athletes to aid the development of explosive ''speed-strength. '' 92 Research on the shock method of training examined drop jump heights PO Box 100154, HSC, Gainesville, FL 32610. E-mail:tchm@ufl.edu of over 3 m, which possibly pushed the limits of safety, but also demonstrated the high-intensity of early plyometric techniques.

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Distribution of Heterogenic Reflexes Among the Quadriceps and Triceps Surae Muscles of the Cat Hind Limb

Cited by 68 publications

References 63 publications

Asymmetric interjoint feedback contributes to postural control of redundant multi-link systems

Asymmetric interjoint feedback contributes to postural control of redundant multi-link systems

Stretch reflex coupling between the hip and knee: implications for impaired gait following stroke

Plyometric Exercise in the Rehabilitation of Athletes: Physiological Responses and Clinical Application

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