Plantar feedback contributes to the regulation of leg stiffness

Fiolkowski, Paul; Bishop, Mark D.; Brunt, Denis; Williams, Blaise

doi:10.1016/j.clinbiomech.2005.03.013

Cited by 32 publications

(17 citation statements)

References 59 publications

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“…Such reduced force levels may trigger mechanisms that compensate for plantarflexor ‘weakness’, as happens in patients (Nadeau et al. , 1999; Beres‐Jones & Harkema, 2004) or during unilateral ischemic block of the distal leg muscles in healthy subjects (Dickey & Winter, 1992), and regulate leg stiffness (Fiolkowski et al. , 2005), by activating proximal extensors.…”

Section: Discussionsupporting

confidence: 93%

Spatiotemporal organization of α‐motoneuron activity in the human spinal cord during different gaits and gait transitions

Ivanenko

Cappellini

Poppele

et al. 2008

Eur J of Neuroscience

112

149

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Here we studied the spatiotemporal organization of motoneuron (MN) activity during different human gaits. We recorded the electromyographic (EMG) activity patterns in 32 ipsilateral limb and trunk muscles from normal subjects while running and walking on a treadmill (3-12 km/h). In addition, we recorded backward walking and skipping, a distinct human gait that comprises the features of both walking and running. We mapped the recorded EMG activity patterns onto the spinal cord in approximate rostrocaudal locations of the MN pools. The activation of MNs tends to occur in bursts and be segregated by spinal segment in a gait-specific manner. In particular, sacral and cervical activation timings were clearly gait-dependent. Swing-related activity constituted an appreciable fraction (> 30%) of the total MN activity of leg muscles. Locomoting at non-preferred speeds (running and walking at 5 and 9 km/h, respectively) showed clear differences relative to preferred speeds. Running at low speeds was characterized by wider sacral activation. Walking at high non-preferred speeds was accompanied by an 'atypical' locus of activation in the upper lumbar spinal cord during late stance and by a drastically increased activation of lumbosacral segments. The latter findings suggest that the optimal speed of gait transitions may be related to an optimal intensity of the total MN activity, in addition to other factors previously described. The results overall support the idea of flexibility and adaptability of spatiotemporal activity in the spinal circuitry with constraints on the temporal functional connectivity of hypothetical pulsatile burst generators.

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Section: Discussionsupporting

confidence: 93%

Spatiotemporal organization of α‐motoneuron activity in the human spinal cord during different gaits and gait transitions

Ivanenko

Cappellini

Poppele

et al. 2008

Eur J of Neuroscience

112

149

View full text Add to dashboard Cite

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“…The percentage was determined from sources with astronaut anthropometric data 2,3,76 and could range from upper:lower ratios of 40%:60% to 60%:40%. Our calculation of the force transmitted to the proximal femur during standing falls on earth Prasad and King, 104 Renau et al, 105 Duma et al, 30 Yoganandan et al Fiolkowski et al, 42 Chi and Schmitt, 19 Lafortune et al, 64 Arampatzis et al, [4][5][6][7] Granata et al, 49 Ferris et al, 40 74 Muller et al, 88 Chiu and Robinovitch, 20 Davidson et al, 26 Staebler et al, 121 and in the reduced gravity environments of the moon and Mars were augmented to account for:…”

Section: Biomechanical Loading Modelsmentioning

confidence: 99%

“…19,20,26,83 As shown in Fig. 3c, it incorporated three lumped masses (head, arms and trunk (HAT); pelvis and legs (PL); and feet (F)), a spring and damper between the HAT mass and the PL mass to represent the stiffness and damping characteristics of the lumbar spine, 30,56,104,105 a spring between the PL mass and the F mass to represent the stiffness characteristics of the legs, [4][5][6][7]19,39,40,42,49,64,100 and a spring and damper between the F mass and ground to represent the stiffness and damping characteristics at the ground. 4,7,19,40,41,85 The loading model for the wrist when it is used to break a fall was based on Chiu and Robinovitch.…”

Section: Biomechanical Loading Modelsmentioning

confidence: 99%

Development and Validation of a Predictive Bone Fracture Risk Model for Astronauts

et al. 2009

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There are still many unknowns in the physiological response of human beings to space, but compelling evidence indicates that accelerated bone loss will be a consequence of long-duration spaceflight. Lacking phenomenological data on fracture risk in space, we have developed a predictive tool based on biomechanical and bone loading models at any gravitational level of interest. The tool is a statistical model that forecasts fracture risk, bounds the associated uncertainties, and performs sensitivity analysis. In this paper, we focused on events that represent severe consequences for an exploration mission, specifically that of spinal fracture resulting from a routine task (lifting a heavy object up to 60 kg), or a spinal, femoral or wrist fracture due to an accidental fall or an intentional jump from 1 to 2 m. We validated the biomechanical and bone fracture models against terrestrial studies of ground reaction forces, skeletal loading, fracture risk, and fracture incidence. Finally, we predicted fracture risk associated with reference missions to the moon and Mars that represented crew activities on the surface. Fracture was much more likely on Mars due to compromised bone integrity. No statistically significant gender-dependent differences emerged. Wrist fracture was the most likely type of fracture, followed by spinal and hip fracture.

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“…Moreover, biomechanical simulations of the compensatory strategies in response to muscle weakness do not seem to predict the appearance of “atypical” burst of activity in the proximal extensors (Goldberg and Neptune, 2007). Perhaps a complete consideration of all factors affecting gait optimization is necessary, including a 3D rather than 2D musculoskeletal gait model (e.g., Gmed, TFL, and SART may generate a noticeable trunk torsion or lateral force component, Dostal et al, 1986) and taking into account the mechanisms that regulate leg stiffness during walking (Fiolkowski et al, 2005). …”

Section: Locomotor Patterns In Peripheral Lesionsmentioning

confidence: 99%

Plasticity and modular control of locomotor patterns in neurological disorders with motor deficits

Ivanenko¹,

Cappellini²,

Солопова³

et al. 2013

Front. Comput. Neurosci.

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Human locomotor movements exhibit considerable variability and are highly complex in terms of both neural activation and biomechanical output. The building blocks with which the central nervous system constructs these motor patterns can be preserved in patients with various sensory-motor disorders. In particular, several studies highlighted a modular burst-like organization of the muscle activity. Here we review and discuss this issue with a particular emphasis on the various examples of adaptation of locomotor patterns in patients (with large fiber neuropathy, amputees, stroke and spinal cord injury). The results highlight plasticity and different solutions to reorganize muscle patterns in both peripheral and central nervous system lesions. The findings are discussed in a general context of compensatory gait mechanisms, spatiotemporal architecture and modularity of the locomotor program.

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Plantar feedback contributes to the regulation of leg stiffness

Cited by 32 publications

References 59 publications

Spatiotemporal organization of α‐motoneuron activity in the human spinal cord during different gaits and gait transitions

Spatiotemporal organization of α‐motoneuron activity in the human spinal cord during different gaits and gait transitions

Development and Validation of a Predictive Bone Fracture Risk Model for Astronauts

Plasticity and modular control of locomotor patterns in neurological disorders with motor deficits

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