Biomechanical Insights into Neural Control of Movement

Zernicke, Ronald F.; Smith, Judith Lee

doi:10.1002/cphy.cp120108

Cited by 15 publications

(8 citation statements)

References 151 publications

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“…Although some variation in motor patterns across individuals was present in all the muscles we were able to sample from multiple turtles, patterns for flexor digitorum longus appeared much more consistent (i.e., stereotyped: Wainwright et al,2008) across the seven individuals we sampled than patterns for the other muscles, which were generally evaluated from fewer individuals. Although, as noted above, some of the variation we observed in motor patterns for several muscles (particularly across individuals) may reflect differences in electrode placement, it is also likely that much step‐to‐step variation reflects adjustments to minor differences in foot placement or other sensory input (Zernicke and Smith,1996). Although variation in motor output for a specific behavior is distinct from the flexibility of motor output across behaviors, the two are often correlated (Wainwright et al,2008).…”

Section: Discussionmentioning

confidence: 80%

“…In many limbed vertebrates, the muscles that control limb movements are highly redundant systems, with multiple potential synergists and antagonists situated in positions that can generate or restrict movement at a particular joint (Macpherson,1991; Roy et al,1991; Biewener and Gillis,1999; Gillis and Blob,2001; Kargo and Rome,2002; Reilly and Blob,2003). A variety of factors may influence which muscles among a group of potential synergists are actually active during the production of a particular motor behavior (Zernicke and Smith,1996; Biewener and Gillis,1999; Gillis and Blob,2001). For example, if muscles across a joint show differences in fiber type proportions, primarily slow oxidative muscles might be activated for slower motions, whereas primarily fast oxidative‐glycolytic or fast glycolytic muscles might be activated during faster motions.…”

Section: Introductionmentioning

confidence: 99%

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Motor patterns of distal hind limb muscles in walking turtles: Implications for models of limb bone loading

Schoenfuss¹,

Roos²,

Rivera³

et al. 2010

Journal of Morphology

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Previous studies of limb bone loading in walking turtles indicate that the ground reaction force exerts a flexor moment at the ankle during stance, requiring extensor muscle activity to maintain joint equilibrium. Of four proposed ankle extensors in turtles, two (gastrocnemius medialis, pronator profundus) originate on the tibia and fibula, respectively, while the other two (flexor digitorum longus, gastrocnemius lateralis) originate from the distal femur, crossing the flexor aspect of the knee and potentially eliciting compensatory forces from antagonist knee extensor muscles that could contribute to femoral stress. Published bone stress models assume all four proposed ankle extensors are active during stance in turtles. However, if only the ankle extensors that cross the knee were active then femoral stresses might be higher than predicted by published models, whereas if only extensors that do not cross the knee were active then femoral stresses might be lower than predicted. We analyzed synchronized footfall and electromyographic activity patterns in slider turtles (Trachemys scripta) and found that all four proposed ankle extensors were active during at least part of stance phase in most individuals, corroborating bone stress models. However, activation patterns were complex, with multiple bursts in many ankle extensors that frequently persisted into swing phase. In addition, two hypothesized ankle flexors (tibialis anterior, extensor digitorum communis) were frequently active during stance. This might increase the joint moment that ankle extensors must counter, elevating the forces they transfer across the knee joint and, thereby, raising femoral stress. Recognition of these activity patterns may help reconcile differences between evaluations of loads on turtle limbs based on force platform versus in vivo strain studies. Moreover, while some variation in motor patterns for the distal hind limbs of turtles may reflect functional compartmentalization of muscles, it may also indicate flexibility in the control of their limb movements.

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Section: Discussionmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Motor patterns of distal hind limb muscles in walking turtles: Implications for models of limb bone loading

Schoenfuss¹,

Roos²,

Rivera³

et al. 2010

Journal of Morphology

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“…The anthropometric inertial parameters for Chinese adults published by Zheng ( 37 ) were used to determine the location of the center of mass and the moment of inertia of each body segment. According to earlier research ( 9 , 22 , 36 ), at each of the joints of the linked segments, the torque was separated into five categories: net joint torque (NET), gravitational torque (GTT), motion-dependent torque (MDT), contact torque (EXT), and generalized muscle torque (MST). NET is the sum of the other four components:…”

Section: Methodsmentioning

confidence: 99%

How Joint Torques Affect Hamstring Injury Risk in Sprinting Swing–Stance Transition

Sun

Wei

Zhong

et al. 2015

Medicine &Amp; Science in Sports &Amp; Exercise

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PurposeThe potential mechanisms of hamstring strain injuries in athletes are not well understood. The study, therefore, was aimed at understanding hamstring mechanics by studying loading conditions during maximum-effort overground sprinting.MethodsThree-dimensional kinematics and ground reaction force data were collected from eight elite male sprinters sprinting at their maximum effort. Maximal isometric torques of the hip and knee were also collected. Data from the sprinting gait cycle were analyzed via an intersegmental dynamics approach, and the different joint torque components were calculated.ResultsDuring the initial stance phase, the ground reaction force passed anteriorly to the knee and hip, producing an extension torque at the knee and a flexion torque at the hip joint. Thus, the active muscle torque functioned to produce flexion torque at the knee and extension torque at the hip. The maximal muscle torque at the knee joint was 1.4 times the maximal isometric knee flexion torque. During the late swing phase, the muscle torque counterbalanced the motion-dependent torque and acted to flex the knee joint and extend the hip joint. The loading conditions on the hamstring muscles were similar to those of the initial stance phase.ConclusionsDuring both the initial stance and late swing phases, the large passive torques at both the knee and hip joints acted to lengthen the hamstring muscles. The active muscle torques generated mainly by the hamstrings functioned to counteract those passive effects. As a result, during sprinting or high-speed locomotion, the hamstring muscles may be more susceptible to high risk of strain injury during these two phases.

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“…where F Y,Z are external forces (ground^joint reaction forces, gravity) in both directions; a Y,Z are linear accelerations of the centre of gravity; M X are moments exerted by all F Y,Z 's about the CG; I X is moment of inertia about the CG; X is angular acceleration about the CG). Moments that must be introduced to ful¢l equation 3are assumed to be the net result of the stresses occurring in muscle^tendon complexes crossing the speci¢c segmental joints (for more information on inverse dynamics, see Zajac & Gordon (1989); Winter 1990;Enoka 1994;Nigg & Herzog 1994;Zernicke & Smith 1996). The required morphometric data are summarized in table 1.…”

Section: (C) Inverse Dynamicsmentioning

confidence: 99%

Vertical jumping in Galago senegalensis: the quest for an obligate mechanical power amplifier

Aerts

1998

Phil. Trans. R. Soc. Lond. B

207

200

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Bushbabies (Galago senegalensis) are renowned for their phenomenal jumping capacity. It was postulated that mechanical power ampli¢cation must be involved. Dynamic analysis of the vertical jumps performed by two bushbabies con¢rms the need for a power ampli¢er. Inverse dynamics coupled to a geometric musculo-skeletal model were used to elucidate the precise nature of the mechanism powering maximal vertical jumps. Most of the power required for jumping is delivered by the vastus muscle^tendon systems (knee extensor). Comparison with the external joint-powers revealed, however, an important power transport from this extensor (about 65%) to the ankle and the midfoot via the bi-articular calf muscles. Peak power output likely implies elastic recoil of the complex aponeurotic system of the vastus muscle. Patterns of changes in length and tension of the muscle^tendon complex during di¡erent phases of the jump were found which provide strong evidence for substantial power ampli¢cation (Â15). It is argued here that the multiple internal connective tissue sheets and attachment structures of the well-developed bundles of the vastus muscle become increasingly stretched during preparatory crouching and throughout the extension phase, except for the last 13 ms of the push-o¡ (i.e. when power requirements peak). Then, tension in the knee extensors abruptly falls from its maximum, allowing the necessary fast recoil of the tensed tendon structures to occur.

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Biomechanical Insights into Neural Control of Movement

Abstract: The sections in this article are: Analytical Techniques and Terms Biomechanics Terminology Dynamics Variables Single vs. Multiple Degrees of Freedom Free‐Body Diagram Dynamics Techniques Insights from Inverse Dynamics Equations of … Show more

Cited by 15 publications

References 151 publications

Motor patterns of distal hind limb muscles in walking turtles: Implications for models of limb bone loading

Motor patterns of distal hind limb muscles in walking turtles: Implications for models of limb bone loading

How Joint Torques Affect Hamstring Injury Risk in Sprinting Swing–Stance Transition

Vertical jumping in Galago senegalensis: the quest for an obligate mechanical power amplifier

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