8 Rapid Spinal Mechanisms of Motor Coordination

Nichols, T. Richard; Cope, Timothy C.; Abelew, Thomas A.

doi:10.1249/00003677-199900270-00010

Cited by 77 publications

(58 citation statements)

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“…It has been suggested that proprioceptors, such as muscle spindles and Golgi tendon organs, provide information about limb position and force through cortical pathways (31). Nichols et al (31) demonstrated that there were strong monosynap- tic Ia linkages among the vasti muscles; however, the linkages between individual vasti muscles and the RF were weaker.…”

Section: Discussionmentioning

confidence: 99%

“…FORCES GENERATED BY MUSCLE to execute intended movements are regulated by the central nervous system and proprioceptive information (18,31,32,39). Descending command from the central nervous system regulates motor unit recruitment and firing rate so that the desired motor task can proceed (8)(9)(10).…”

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confidence: 99%

“…Considering these observations, it is reasonable to speculate that recruitment can be modulated by afferent feedback during certain conditions, for example fatigue, to maintain required performance. The strong afferent linkages among the vasti but not the RF suggest that the three monoarticulate synergists would show increased use in concert (31). On the other hand, increased central command per se, in an effort to execute the intended act, could explain increased recruitment to maintain force over repeated contractions (8).…”

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confidence: 99%

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Vastus lateralis fatigue alters recruitment of musculus quadriceps femoris in humans

Akima

Foley

Prior³

et al. 2002

Journal of Applied Physiology

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. Vastus lateralis fatigue alters recruitment of musculus quadriceps femoris in humans. J Appl Physiol 92: 679-684, 2002; 10.1152/ japplphysiol.00267.2001.-This study tested the hypothesis that fatigue of a single member of musculus quadriceps femoris (QF) would alter use of the other three muscles during knee extension exercise (KEE). Six men performed KEE with the left QF at a load equal to 50% of the 4 ϫ 10 repetitions maximum. Subsequently, electromyostimulation (EMS), intended to stimulate and fatigue the left m. vastus lateralis (VL), was applied for 30 min. Immediately after EMS, subjects repeated the KEE. Transverse relaxation time (T2)-weighted magnetic resonance images were taken before and after each bout of KEE and at 3 and 30 min of EMS to assess use and stimulation, respectively, of the QF. T2 of each of the QF muscles was increased 8-13% after the first KEE. During EMS, T2 increased (P Ͻ 0.05) even more in VL (10%), whereas it decreased (P Ͻ 0.05) to pre-KEE levels in m. vastus medials (VM) and m. rectus femoris (RF). The VL and, to some extent, the m. vastus intermedius were stimulated, whereas the VM and RF were not, thereby recovering from the first bout of KEE. Isometric torque, initially 30% of maximal voluntary, was reduced to 13% at 3 min and 7% at 30 min. T2 was greater (P Ͻ 0.05) after the second than the first bout of KEE, especially the increase for the VM and RF. These results suggest that subjects were able to perform the second bout with little contribution of the VL by greater use of the other QF muscles. The simplest explanation is increased central command to the QF such that the intended act could be accomplished despite acute fatigue of one of its synergists.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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Vastus lateralis fatigue alters recruitment of musculus quadriceps femoris in humans

Akima

Foley

Prior³

et al. 2002

Journal of Applied Physiology

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“…However, in human subjects, reflex control does not mimic a servo-like system (Crago, Houk & Hasan, 1976), and similarly, in cats the variation in intermuscular feedback gains measured in vivo varies among muscles crossing a single joint (Nichols, 1989). Short latency spindle reflexes modulate activity of many heteronymous muscles (Eccles, 1956;Eccles, Eccles & Lundberg, 1957b;Nichols, 1989), and it seems that reflex mechanisms can provide an integrated control system, spanning and coordinating multiple joints (Nichols, Cope & Abelew, 1999;Perreault & Viant, 2005). This heterogenic feedback can be asymmetric, favoring force generation by one muscle of a pair, or at one joint over another (Bonasera & Nichols, 1994;Eccles & Lundberg, 1958;Nichols et al, 1999;Pratt, 1995).…”

Section: Introductionmentioning

confidence: 99%

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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“…Most studies failed to show a relation between quadriceps muscle CSA, morphological measures, and muscle strength in ACL-deficient patients [66,68,69]. Muscle volume appears to be a better indicator for atrophy than muscle torque because the latter is patient-dependent [70].…”

Section: Causes Of Quadriceps Weaknessmentioning

confidence: 99%

Prehabilitation: The Void in the Management of Anterior Cruciate Ligament Injuries—A Clinical Review

Shaarani

Moyna

Moran

et al. 2012

ISRN Rehabilitation

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The rehabilitation of patients undergoing anterior cruciate ligament (ACL) reconstruction requires symmetry in bilateral quadriceps strength and adequate proprioception capabilities prior to return to preoperative level of activity or sport. This is the limiting factor and can delay the time that patients can return to play. There is little literature on pre-operative physiotherapy or prehabilitation of patient with ACL injury. This paper discusses the anatomy, biomechanics, surgical decision making, and the current knowledge of preoperative training or "prehabilitation" in patients awaiting ACL reconstruction.

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8 Rapid Spinal Mechanisms of Motor Coordination

Cited by 77 publications

References 0 publications

Vastus lateralis fatigue alters recruitment of musculus quadriceps femoris in humans

Vastus lateralis fatigue alters recruitment of musculus quadriceps femoris in humans

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

Prehabilitation: The Void in the Management of Anterior Cruciate Ligament Injuries—A Clinical Review

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