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Charles JP, Cappellari O, Hutchinson JR. A Dynamic Simulation of Musculoskeletal Function in the Mouse Hindlimb During Trotting Locomotion. Front Bioeng Biotechnol 2018; 6:61. [PMID: 29868576 PMCID: PMC5964171 DOI: 10.3389/fbioe.2018.00061] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 04/26/2018] [Indexed: 11/30/2022] Open
Abstract
Mice are often used as animal models of various human neuromuscular diseases, and analysis of these models often requires detailed gait analysis. However, little is known of the dynamics of the mouse musculoskeletal system during locomotion. In this study, we used computer optimization procedures to create a simulation of trotting in a mouse, using a previously developed mouse hindlimb musculoskeletal model in conjunction with new experimental data, allowing muscle forces, activation patterns, and levels of mechanical work to be estimated. Analyzing musculotendon unit (MTU) mechanical work throughout the stride allowed a deeper understanding of their respective functions, with the rectus femoris MTU dominating the generation of positive and negative mechanical work during the swing and stance phases. This analysis also tested previous functional inferences of the mouse hindlimb made from anatomical data alone, such as the existence of a proximo-distal gradient of muscle function, thought to reflect adaptations for energy-efficient locomotion. The results do not strongly support the presence of this gradient within the mouse musculoskeletal system, particularly given relatively high negative net work output from the ankle plantarflexor MTUs, although more detailed simulations could test this further. This modeling analysis lays a foundation for future studies of the control of vertebrate movement through the development of neuromechanical simulations.
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Affiliation(s)
- James P Charles
- Neuromuscular Diseases Group, Department of Comparative Biomedical Sciences, Royal Veterinary College, London, United Kingdom.,Structure and Motion Lab, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, United Kingdom
| | - Ornella Cappellari
- Neuromuscular Diseases Group, Department of Comparative Biomedical Sciences, Royal Veterinary College, London, United Kingdom
| | - John R Hutchinson
- Structure and Motion Lab, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, United Kingdom
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Urbina-Meléndez D, Jalaleddini K, Daley MA, Valero-Cuevas FJ. A Physical Model Suggests That Hip-Localized Balance Sense in Birds Improves State Estimation in Perching: Implications for Bipedal Robots. Front Robot AI 2018; 5:38. [PMID: 33500924 PMCID: PMC7806032 DOI: 10.3389/frobt.2018.00038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Accepted: 03/19/2018] [Indexed: 11/13/2022] Open
Abstract
In addition to a vestibular system, birds uniquely have a balance-sensing organ within the pelvis, called the lumbosacral organ (LSO). The LSO is well developed in terrestrial birds, possibly to facilitate balance control in perching and terrestrial locomotion. No previous studies have quantified the functional benefits of the LSO for balance. We suggest two main benefits of hip-localized balance sense: reduced sensorimotor delay and improved estimation of foot-ground acceleration. We used system identification to test the hypothesis that hip-localized balance sense improves estimates of foot acceleration compared to a head-localized sense, due to closer proximity to the feet. We built a physical model of a standing guinea fowl perched on a platform, and used 3D accelerometers at the hip and head to replicate balance sense by the LSO and vestibular systems. The horizontal platform was attached to the end effector of a 6 DOF robotic arm, allowing us to apply perturbations to the platform analogous to motions of a compliant branch. We also compared state estimation between models with low and high neck stiffness. Cross-correlations revealed that foot-to-hip sensing delays were shorter than foot-to-head, as expected. We used multi-variable output error state-space (MOESP) system identification to estimate foot-ground acceleration as a function of hip- and head-localized sensing, individually and combined. Hip-localized sensors alone provided the best state estimates, which were not improved when fused with head-localized sensors. However, estimates from head-localized sensors improved with higher neck stiffness. Our findings support the hypothesis that hip-localized balance sense improves the speed and accuracy of foot state estimation compared to head-localized sense. The findings also suggest a role of neck muscles for active sensing for balance control: increased neck stiffness through muscle co-contraction can improve the utility of vestibular signals. Our engineering approach provides, to our knowledge, the first quantitative evidence for functional benefits of the LSO balance sense in birds. The findings support notions of control modularity in birds, with preferential vestibular sense for head stability and gaze, and LSO for body balance control,respectively. The findings also suggest advantages for distributed and active sensing for agile locomotion in compliant bipedal robots.
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Affiliation(s)
- Darío Urbina-Meléndez
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States
- School of Engineering, National Autonomous University of Mexico, Mexico City, Mexico
| | - Kian Jalaleddini
- Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA, United States
| | - Monica A Daley
- Comparative Biomedical Sciences, Royal Veterinary College, London, United Kingdom
| | - Francisco J Valero-Cuevas
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States
- Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA, United States
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53
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Lyle MA, Nichols TR. Patterns of intermuscular inhibitory force feedback across cat hindlimbs suggest a flexible system for regulating whole limb mechanics. J Neurophysiol 2018; 119:668-678. [PMID: 29142095 PMCID: PMC5867384 DOI: 10.1152/jn.00617.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 10/17/2017] [Accepted: 11/08/2017] [Indexed: 12/12/2022] Open
Abstract
Prior work has suggested that Golgi tendon organ feedback, via its distributed network linking muscles spanning all joints, could be used by the nervous system to help regulate whole limb mechanics if appropriately organized. We tested this hypothesis by characterizing the patterns of intermuscular force-dependent feedback between the primary extensor muscles spanning the knee, ankle, and toes in decerebrate cat hindlimbs. Intermuscular force feedback was evaluated by stretching tendons of selected muscles in isolation and in pairwise combinations and then measuring the resulting force-dependent intermuscular interactions. The relative inhibitory feedback between extensor muscles was examined, as well as symmetry of the interactions across limbs. Differences in the directional biases of inhibitory feedback were observed across cats, with three patterns identified as points on a spectrum: pattern 1, directional bias of inhibitory feedback onto the ankle extensors and toe flexors; pattern 2, convergence of inhibitory feedback onto ankle extensors and mostly balanced inhibitory feedback between vastus muscle group and flexor hallucis longus, and pattern 3, directional bias of inhibitory feedback onto ankle and knee extensors. The patterns of inhibitory feedback, while different across cats, were symmetric across limbs of individual cats. The variable but structured distribution of force feedback across cat hindlimbs provides preliminary evidence that inhibitory force feedback could be a regulated neural control variable. We propose the directional biases of inhibitory feedback observed experimentally could provide important task-dependent benefits, such as directionally appropriate joint compliance, joint coupling, and compensation for nonuniform inertia. NEW & NOTEWORTHY Feedback from Golgi tendon organs project widely among extensor motor nuclei in the spinal cord. The distributed nature of force feedback suggests these pathways contribute to the global regulation of limb mechanics. Analysis of this network in individual animals indicates that the strengths of these pathways can be reorganized appropriately for a variety of motor tasks, including level walking, slope walking, and landing.
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Affiliation(s)
- Mark A Lyle
- School of Biological Sciences, Georgia Institute of Technology , Atlanta, Georgia
| | - T Richard Nichols
- School of Biological Sciences, Georgia Institute of Technology , Atlanta, Georgia
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54
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Van der Noot N, Ijspeert AJ, Ronsse R. Bio-inspired controller achieving forward speed modulation with a 3D bipedal walker. Int J Rob Res 2018. [DOI: 10.1177/0278364917743320] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Despite all the effort devoted to generating locomotion algorithms for bipedal walkers, robots are still far from reaching the impressive human walking capabilities, for instance regarding robustness and energy consumption. In this paper, we have developed a bio-inspired torque-based controller supporting the emergence of a new generation of robust and energy-efficient walkers. It recruits virtual muscles driven by reflexes and a central pattern generator, and thus requires no computationally intensive inverse kinematics or dynamics modeling. This controller is capable of generating energy-efficient and human-like gaits (both regarding kinematics and dynamics) across a large range of forward speeds, in a 3D environment. After a single off-line optimization process, the forward speed can be continuously commanded within this range by changing high-level parameters, as linear or quadratic functions of the target speed. Sharp speed transitions can then be achieved with no additional tuning, resulting in immediate adaptations of the step length and frequency. In this paper, we particularly embodied this controller on a simulated version of COMAN, a 95 cm tall humanoid robot. We reached forward speed modulations between 0.4 and 0.9 m/s. This covers normal human walking speeds once scaled to the robot size. Finally, the walker demonstrated significant robustness against a large spectrum of unpredicted perturbations: facing external pushes or walking on altered environments, such as stairs, slopes, and irregular ground.
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Affiliation(s)
- Nicolas Van der Noot
- Center for Research in Mechatronics, Institute of Mechanics, Materials and Civil Engineering, and “Louvain Bionics”, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
- Biorobotics Laboratory, Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Auke Jan Ijspeert
- Biorobotics Laboratory, Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Renaud Ronsse
- Center for Research in Mechatronics, Institute of Mechanics, Materials and Civil Engineering, and “Louvain Bionics”, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
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55
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Hind limb extensor muscle architecture reflects locomotor specialisations of a jumping and a striding quadrupedal caviomorph rodent. ZOOMORPHOLOGY 2017. [DOI: 10.1007/s00435-017-0349-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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56
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Lauer J, Rouard AH, Vilas-Boas JP. Modulation of upper limb joint work and power during sculling while ballasted with varying loads. ACTA ACUST UNITED AC 2017; 220:1729-1736. [PMID: 28250107 DOI: 10.1242/jeb.154781] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 02/17/2017] [Indexed: 11/20/2022]
Abstract
The human musculoskeletal system must modulate work and power output in response to substantial alterations in mechanical demands associated with different tasks. In particular, in water, upper limb muscles must perform net positive work to replace the energy lost against the dissipative fluid load. Where in the upper limb are work and power developed? Is mechanical output modulated similarly at all joints, or are certain muscle groups favored? This study examined, for the first time, how work and power per stroke are distributed at the upper limb joints in seven male participants sculling while ballasted with 4, 6, 8, 10 and 12 kg. Upper limb kinematics was captured and used to animate body virtual geometry. Net wrist, elbow and shoulder joint work and power were subsequently computed through a novel approach integrating unsteady numerical fluid flow simulations and inverse dynamics modeling. Across a threefold increase in load, total work and power significantly increased from 0.38±0.09 to 0.67±0.13 J kg-1, and 0.47±0.06 to 1.14±0.16 W kg-1, respectively. Shoulder and elbow equally supplied >97% of the upper limb total work and power, coherent with the proximo-distal gradient of work performance in the limbs of terrestrial animals. Individual joint relative contributions remained constant, as observed on land during tasks necessitating no net work. The apportionment of higher work and power simultaneously at all joints in water suggests a general motor strategy of power modulation consistent across physical environments, limbs and tasks, regardless of whether or not they demand positive net work.
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Affiliation(s)
- Jessy Lauer
- Center of Research, Education, Innovation and Intervention in Sport, Faculty of Sport; and Porto Biomechanics Laboratory, University of Porto, 4200-450 Porto, Portugal .,Inter-university Laboratory of Human Movement Science, University Savoie Mont Blanc, 73376 Le Bourget-du-Lac, France
| | - Annie Hélène Rouard
- Inter-university Laboratory of Human Movement Science, University Savoie Mont Blanc, 73376 Le Bourget-du-Lac, France
| | - João Paulo Vilas-Boas
- Center of Research, Education, Innovation and Intervention in Sport, Faculty of Sport; and Porto Biomechanics Laboratory, University of Porto, 4200-450 Porto, Portugal
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57
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Ackerman J, Potwar K, Seipel J. Suspending loads decreases load stability but may slightly improve body stability. J Biomech 2017; 52:38-47. [PMID: 28093259 DOI: 10.1016/j.jbiomech.2016.12.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 12/02/2016] [Accepted: 12/02/2016] [Indexed: 10/20/2022]
Abstract
Here, we seek to determine how compliantly suspended loads could affect the dynamic stability of legged locomotion. We theoretically model the dynamic stability of a human carrying a load using a coupled spring-mass-damper model and an actuated spring-loaded inverted pendulum model, as these models have demonstrated the ability to correctly predict other aspects of locomotion with a load in prior work, such as body forces and energetic cost. We report that minimizing the load suspension natural frequency and damping ratio significantly reduces the stability of the load mass but may slightly improve the body stability of locomotion when compared to a rigidly attached load. These results imply that a highly-compliant load suspension could help stabilize body motion during human, animal, or robot load carriage, but at the cost of a more awkward (less stable) load.
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Affiliation(s)
- Jeffrey Ackerman
- School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907, United States
| | - Karna Potwar
- School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907, United States
| | - Justin Seipel
- School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907, United States.
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58
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Moore JM, McKinley PK. Evolution of Joint-Level Control for Quadrupedal Locomotion. ARTIFICIAL LIFE 2017; 23:58-79. [PMID: 28140629 DOI: 10.1162/artl_a_00222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We investigate a hierarchical approach to robot control inspired by joint-level control in animals. The method combines a high-level controller, consisting of an artificial neural network (ANN), with joint-level controllers based on digital muscles. In the digital muscle model (DMM), morphological and control aspects of joints evolve concurrently, emulating the musculoskeletal system of natural organisms. We introduce and compare different approaches for connecting outputs of the ANN to DMM-based joints. We also compare the performance of evolved animats with ANN-DMM controllers with those governed by only high-level (ANN-only) and low-level (DMM-only) controllers. These results show that DMM-based systems outperform their ANN-only counterparts while also exhibiting less complex ANNs in terms of the number of connections and neurons. The main contribution of this work is to explore the evolution of artificial systems where, as in natural organisms, some aspects of control are realized at the joint level.
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59
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Qiao M, Abbas JJ, Jindrich DL. A model for differential leg joint function during human running. BIOINSPIRATION & BIOMIMETICS 2017; 12:016015. [PMID: 28134133 DOI: 10.1088/1748-3190/aa50b0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Locomotion requires coordination of leg joints to maintain stability and to maneuver. We studied leg joint function during constant-average-velocity running and the sagittal-plane maneuvers of step ascent and descent. We tested two hypotheses: (1) that leg joints perform distinct functions during locomotion; and (2) that humans select functional parameters to maximize intrinsic dynamic stability. We recorded whole-body kinematics and forces when participants stepped up or down a single vertical step, and found that leg joints show functional differences during both constant-average-velocity locomotion and maneuvers. The hip, knee and ankle function as a motor, damper, and spring, respectively. We therefore constructed a simplified computational model of a human leg with a motor, damper, and spring in series (MDS). The intrinsic dynamics of the model resulted in sustained locomotion on level ground within narrow parameter ranges. However, using parameters experimentally derived from humans, the model showed only short-term stability. Humans may not optimize intrinsic dynamic stability alone, but may instead choose mechanical and behavioral parameters appropriate for both constant-average-velocity locomotion and maneuvers. Understanding joint-level mechanical function during unsteady locomotion helps to understand how differential joint function contributes to whole-body performance, and could lead to improvements in rehabilitation, prosthetic and robotic design.
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Affiliation(s)
- Mu Qiao
- Kinesiology Program, School of Nutrition and Health Promotion, Arizona State University, Phoenix, AZ 85004-0698, USA. Center for Adaptive Neural Systems, School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ 85287-4404, USA
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60
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Xiong X, Worgotter F, Manoonpong P. Adaptive and Energy Efficient Walking in a Hexapod Robot Under Neuromechanical Control and Sensorimotor Learning. IEEE TRANSACTIONS ON CYBERNETICS 2016; 46:2521-2534. [PMID: 26441437 DOI: 10.1109/tcyb.2015.2479237] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The control of multilegged animal walking is a neuromechanical process, and to achieve this in an adaptive and energy efficient way is a difficult and challenging problem. This is due to the fact that this process needs in real time: 1) to coordinate very many degrees of freedom of jointed legs; 2) to generate the proper leg stiffness (i.e., compliance); and 3) to determine joint angles that give rise to particular positions at the endpoints of the legs. To tackle this problem for a robotic application, here we present a neuromechanical controller coupled with sensorimotor learning. The controller consists of a modular neural network for coordinating 18 joints and several virtual agonist-antagonist muscle mechanisms (VAAMs) for variable compliant joint motions. In addition, sensorimotor learning, including forward models and dual-rate learning processes, is introduced for predicting foot force feedback and for online tuning the VAAMs' stiffness parameters. The control and learning mechanisms enable the hexapod robot advanced mobility sensor driven-walking device (AMOS) to achieve variable compliant walking that accommodates different gaits and surfaces. As a consequence, AMOS can perform more energy efficient walking, compared to other small legged robots. In addition, this paper also shows that the tight combination of neural control with tunable muscle-like functions, guided by sensory feedback and coupled with sensorimotor learning, is a way forward to better understand and solve adaptive coordination problems in multilegged locomotion.
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61
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Müller R, Birn-Jeffery AV, Blum Y. Human and avian running on uneven ground: a model-based comparison. J R Soc Interface 2016; 13:rsif.2016.0529. [PMID: 27655670 DOI: 10.1098/rsif.2016.0529] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 08/25/2016] [Indexed: 01/01/2023] Open
Abstract
Birds and humans are successful bipedal runners, who have individually evolved bipedalism, but the extent of the similarities and differences of their bipedal locomotion is unknown. In turn, the anatomical differences of their locomotor systems complicate direct comparisons. However, a simplifying mechanical model, such as the conservative spring-mass model, can be used to describe both avian and human running and thus, provides a way to compare the locomotor strategies that birds and humans use when running on level and uneven ground. Although humans run with significantly steeper leg angles at touchdown and stiffer legs when compared with cursorial ground birds, swing-leg adaptations (leg angle and leg length kinematics) used by birds and humans while running appear similar across all types of uneven ground. Nevertheless, owing to morphological restrictions, the crouched avian leg has a greater range of leg angle and leg length adaptations when coping with drops and downward steps than the straight human leg. On the other hand, the straight human leg seems to use leg stiffness adaptation when coping with obstacles and upward steps unlike the crouched avian leg posture.
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Affiliation(s)
- R Müller
- Motionscience, Friedrich-Schiller-University Jena, Jena, Germany
| | - A V Birn-Jeffery
- Department of Zoology, University of Cambridge, Cambridge, UK Centre for Sports and Exercise Medicine, Queen Mary University of London, Mile End Hospital, Bancroft Road, London E1 4DG, UK
| | - Y Blum
- Motionscience, Friedrich-Schiller-University Jena, Jena, Germany
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62
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Martin AE, Villarreal DJ, Gregg RD. Characterizing and modeling the joint-level variability in human walking. J Biomech 2016; 49:3298-3305. [PMID: 27594679 DOI: 10.1016/j.jbiomech.2016.08.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 08/15/2016] [Accepted: 08/15/2016] [Indexed: 11/18/2022]
Abstract
Although human gait is often assumed to be periodic, significant variability exists. This variability appears to provide different information than the underlying periodic signal, particularly about fall risk. Most studies on variability have either used step-to-step metrics such as stride duration or point-wise standard deviations, neither of which explicitly capture the joint-level variability as a function of time. This work demonstrates that a second-order Fourier series for stance joints and a first-order Fourier series for swing joints can accurately capture the variability in joint angles as a function of time on a per-step basis for overground walking at the self-selected speed. It further demonstrates that a total of seven normal distributions, four linear relationships, and twelve continuity constraints can be used to describe how the Fourier series vary between steps. The ability of the proposed method to create curves that match human joint-level variability was evaluated both qualitatively and quantitatively using randomly generated curves.
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Affiliation(s)
- Anne E Martin
- Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA16802, USA.
| | - Dario J Villarreal
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Robert D Gregg
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA; Department of Mechanical Engineering, University of Texas at Dallas, Richardson, TX 75080, USA.
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63
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McClymont J, Pataky TC, Crompton RH, Savage R, Bates KT. The nature of functional variability in plantar pressure during a range of controlled walking speeds. ROYAL SOCIETY OPEN SCIENCE 2016; 3:160369. [PMID: 27853618 PMCID: PMC5108968 DOI: 10.1098/rsos.160369] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 07/21/2016] [Indexed: 05/29/2023]
Abstract
During walking, variability in step parameters allows the body to adapt to changes in substrate or unexpected perturbations that may occur as the feet interface with the environment. Despite a rich literature describing biomechanical variability in step parameters, there are as yet no studies that consider variability at the body-environment interface. Here, we used pedobarographic statistical parametric mapping (pSPM) and two standard measures of variability, mean square error (m.s.e.) and the coefficient of variation (CV), to assess the magnitude and spatial variability in plantar pressure across a range of controlled walking speeds. Results by reduced major axis, and pSPM regression, revealed no consistent linear relationship between m.s.e. and speed or m.s.e. and Froude number. A positive linear relationship, however, was found between CV and walking speed and CV and Froude number. The spatial distribution of variability was highly disparate when assessed by m.s.e. and CV: relatively high variability was consistently confined to the medial and lateral forefoot when measured by m.s.e., while the forefoot and heel show high variability when measured by CV. In absolute terms, variability by CV was universally low (less than 2.5%). From these results, we determined that variability as assessed by m.s.e. is independent of speed, but dependent on speed when assessed by CV.
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Affiliation(s)
- Juliet McClymont
- Institute of Ageing and Chronic Disease, William Duncan Building, L7 8TX Liverpool, UK
| | - Todd C. Pataky
- Institute for Fiber Engineering, Shinshu University, Ueda, Japan
| | - Robin H. Crompton
- Institute of Ageing and Chronic Disease, William Duncan Building, L7 8TX Liverpool, UK
| | - Russell Savage
- Institute of Ageing and Chronic Disease, William Duncan Building, L7 8TX Liverpool, UK
| | - Karl T. Bates
- Institute of Ageing and Chronic Disease, William Duncan Building, L7 8TX Liverpool, UK
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64
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Toney ME, Chang YH. The motor and the brake of the trailing leg in human walking: leg force control through ankle modulation and knee covariance. Exp Brain Res 2016; 234:3011-23. [PMID: 27334888 DOI: 10.1007/s00221-016-4703-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 06/13/2016] [Indexed: 10/21/2022]
Abstract
Human walking is a complex task, and we lack a complete understanding of how the neuromuscular system organizes its numerous muscles and joints to achieve consistent and efficient walking mechanics. Focused control of select influential task-level variables may simplify the higher-level control of steady-state walking and reduce demand on the neuromuscular system. As trailing leg power generation and force application can affect the mechanical efficiency of step-to-step transitions, we investigated how joint torques are organized to control leg force and leg power during human walking. We tested whether timing of trailing leg force control corresponded with timing of peak leg power generation. We also applied a modified uncontrolled manifold analysis to test whether individual or coordinated joint torque strategies most contributed to leg force control. We found that leg force magnitude was adjusted from step to step to maintain consistent leg power generation. Leg force modulation was primarily determined by adjustments in the timing of peak ankle plantar-flexion torque, while knee torque was simultaneously covaried to dampen the effect of ankle torque on leg force. We propose a coordinated joint torque control strategy in which the trailing leg ankle acts as a motor to drive leg power production while trailing leg knee torque acts as a brake to refine leg power production.
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Affiliation(s)
- Megan E Toney
- School of Applied Physiology, Georgia Institute of Technology, Atlanta, GA, USA
| | - Young-Hui Chang
- School of Applied Physiology, Georgia Institute of Technology, Atlanta, GA, USA. .,Comparative Neuromechanics Laboratory, School of Applied Physiology, Georgia Institute of Technology, 555 14th St NW, Atlanta, GA, 30332-0356, USA.
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65
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Villarreal DJ, Poonawala HA, Gregg RD. A Robust Parameterization of Human Gait Patterns Across Phase-Shifting Perturbations. IEEE Trans Neural Syst Rehabil Eng 2016; 25:265-278. [PMID: 27187967 DOI: 10.1109/tnsre.2016.2569019] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The phase of human gait is difficult to quantify accurately in the presence of disturbances. In contrast, recent bipedal robots use time-independent controllers relying on a mechanical phase variable to synchronize joint patterns through the gait cycle. This concept has inspired studies to determine if human joint patterns can also be parameterized by a mechanical variable. Although many phase variable candidates have been proposed, it remains unclear which, if any, provide a robust representation of phase for human gait analysis or control. In this paper we analytically derive an ideal phase variable (the hip phase angle) that is provably monotonic and bounded throughout the gait cycle. To examine the robustness of this phase variable, ten able-bodied human subjects walked over a platform that randomly applied phase-shifting perturbations to the stance leg. A statistical analysis found the correlations between nominal and perturbed joint trajectories to be significantly greater when parameterized by the hip phase angle (0.95+) than by time or a different phase variable. The hip phase angle also best parameterized the transient errors about the nominal periodic orbit. Finally, interlimb phasing was best explained by local (ipsilateral) hip phase angles that are synchronized during the double-support period.
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66
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Musculoskeletal Geometry, Muscle Architecture and Functional Specialisations of the Mouse Hindlimb. PLoS One 2016; 11:e0147669. [PMID: 27115354 PMCID: PMC4846001 DOI: 10.1371/journal.pone.0147669] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 01/06/2016] [Indexed: 01/19/2023] Open
Abstract
Mice are one of the most commonly used laboratory animals, with an extensive array of disease models in existence, including for many neuromuscular diseases. The hindlimb is of particular interest due to several close muscle analogues/homologues to humans and other species. A detailed anatomical study describing the adult morphology is lacking, however. This study describes in detail the musculoskeletal geometry and skeletal muscle architecture of the mouse hindlimb and pelvis, determining the extent to which the muscles are adapted for their function, as inferred from their architecture. Using I2KI enhanced microCT scanning and digital segmentation, it was possible to identify 39 distinct muscles of the hindlimb and pelvis belonging to nine functional groups. The architecture of each of these muscles was determined through microdissections, revealing strong architectural specialisations between the functional groups. The hip extensors and hip adductors showed significantly stronger adaptations towards high contraction velocities and joint control relative to the distal functional groups, which exhibited larger physiological cross sectional areas and longer tendons, adaptations for high force output and elastic energy savings. These results suggest that a proximo-distal gradient in muscle architecture exists in the mouse hindlimb. Such a gradient has been purported to function in aiding locomotor stability and efficiency. The data presented here will be especially valuable to any research with a focus on the architecture or gross anatomy of the mouse hindlimb and pelvis musculature, but also of use to anyone interested in the functional significance of muscle design in relation to quadrupedal locomotion.
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67
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Kiely J, Collins DJ. Uniqueness of Human Running Coordination: The Integration of Modern and Ancient Evolutionary Innovations. Front Psychol 2016; 7:262. [PMID: 27148098 PMCID: PMC4826868 DOI: 10.3389/fpsyg.2016.00262] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 02/10/2016] [Indexed: 12/26/2022] Open
Abstract
Running is a pervasive activity across human cultures and a cornerstone of contemporary health, fitness, and sporting activities. Yet for the overwhelming predominance of human existence running was an essential prerequisite for survival. A means to hunt, and a means to escape when hunted. In a very real sense humans have evolved to run. Yet curiously, perhaps due to running's cultural ubiquity and the natural ease with which we learn to run, we rarely consider the uniqueness of human bipedal running within the animal kingdom. Our unique upright, single stance, bouncing running gait imposes a unique set of coordinative difficulties. Challenges demanding we precariously balance our fragile brains in the very position where they are most vulnerable to falling injury while simultaneously retaining stability, steering direction of travel, and powering the upcoming stride: all within the abbreviated time-frames afforded by short, violent ground contacts separated by long flight times. These running coordination challenges are solved through the tightly-integrated blending of primitive evolutionary legacies, conserved from reptilian and vertebrate lineages, and comparatively modern, more exclusively human, innovations. The integrated unification of these top-down and bottom-up control processes bestows humans with an agile control system, enabling us to readily modulate speeds, change direction, negotiate varied terrains and to instantaneously adapt to changing surface conditions. The seamless integration of these evolutionary processes is facilitated by pervasive, neural and biological, activity-dependent adaptive plasticity. Over time, and with progressive exposure, this adaptive plasticity shapes neural and biological structures to best cope with regularly imposed movement challenges. This pervasive plasticity enables the gradual construction of a robust system of distributed coordinated control, comprised of processes that are so deeply collectively entwined that describing their functionality in isolation obscures their true irrevocably entangled nature. Although other species rely on a similar set of coordinated processes to run, the bouncing bipedal nature of human running presents a specific set of coordination challenges, solved using a customized blend of evolved solutions. A deeper appreciation of the foundations of the running coordination phenomenon promotes conceptual clarity, potentially informing future advances in running training and running-injury rehabilitation interventions.
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Affiliation(s)
- John Kiely
- School of Health and Wellbeing, Institute of Coaching and Performance, University of Central LancashirePreston, UK; Fitness Department, Irish Rugby Football UnionDublin, Ireland
| | - David J Collins
- School of Health and Wellbeing, Institute of Coaching and Performance, University of Central Lancashire Preston, UK
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68
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Piovan G, Byl K. Approximation and Control of the SLIP Model Dynamics via Partial Feedback Linearization and Two-Element Leg Actuation Strategy. IEEE T ROBOT 2016. [DOI: 10.1109/tro.2016.2529649] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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69
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Birn-Jeffery AV, Higham TE. Geckos decouple fore- and hind limb kinematics in response to changes in incline. Front Zool 2016; 13:11. [PMID: 26941828 PMCID: PMC4776376 DOI: 10.1186/s12983-016-0144-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2015] [Accepted: 02/25/2016] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND Terrestrial animals regularly move up and down surfaces in their natural habitat, and the impacts of moving uphill on locomotion are commonly examined. However, if an animal goes up, it must go down. Many morphological features enhance locomotion on inclined surfaces, including adhesive systems among geckos. Despite this, it is not known whether the employment of the adhesive system results in altered locomotor kinematics due to the stereotyped motions that are necessary to engage and disengage the system. Using a generalist pad-bearing gecko, Chondrodactylus bibronii, we determined whether changes in slope impact body and limb kinematics. RESULTS Despite the change in demand, geckos did not change speed on any incline. This constant speed was achieved by adjusting stride frequency, step length and swing time. Hind limb, but not forelimb, kinematics were altered on steep downhill conditions, thus resulting in significant de-coupling of the limbs. CONCLUSIONS Unlike other animals on non-level conditions, the geckos in our study only minimally alter the movements of distal limb elements, which is likely due to the constraints associated with the need for rapid attachment and detachment of the adhesive system. This suggests that geckos may experience a trade-off between successful adhesion and the ability to respond dynamically to locomotor perturbations.
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Affiliation(s)
- Aleksandra V. Birn-Jeffery
- />Department of Zoology, University of Cambridge, Downing Street, Cambridge, UK
- />Department of Biology, University of California, 900 University Avenue, Riverside, CA 92521 USA
| | - Timothy E. Higham
- />Department of Biology, University of California, 900 University Avenue, Riverside, CA 92521 USA
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70
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Villarreal DJ, Quintero D, Gregg RD. A Perturbation Mechanism for Investigations of Phase-Dependent Behavior in Human Locomotion. IEEE ACCESS : PRACTICAL INNOVATIONS, OPEN SOLUTIONS 2016; 4:893-904. [PMID: 27570719 PMCID: PMC4996277 DOI: 10.1109/access.2016.2535661] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Bipedal locomotion is a popular area of study across multiple fields (e.g., biomechanics, neuroscience and robotics). Different hypotheses and models have tried explaining how humans achieve stable locomotion. Perturbations that produce shifts in the nominal periodic orbit of the joint kinematics during locomotion could inform about the manner in which the human neuromechanics represent the phase of gait. Ideally, this type of perturbation would modify the progression of the human subject through the gait cycle without deviating from the nominal kinematic orbits of the leg joints. However, there is a lack of publicly available experimental data with this type of perturbation. This paper presents the design and validation of a perturbation mechanism and an experimental protocol capable of producing phase-shifting perturbations of the gait cycle. The effects of this type of perturbation on the gait cycle are statistically quantified and analyzed in order to show that a clean phase shift in the gait cycle was achieved. The data collected during these experiments will be publicly available for the scientific community to test different hypotheses and models of human locomotion.
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Affiliation(s)
- Dario J. Villarreal
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA
| | - David Quintero
- Department of Mechanical Engineering, University of Texas at Dallas, Richardson, TX 75080, USA
| | - Robert D. Gregg
- Departments of Bioengineering and Mechanical Engineering, University of Texas at Dallas, Richardson, TX 75080, USA
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71
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Qiao M, Jindrich DL. Leg joint function during walking acceleration and deceleration. J Biomech 2016; 49:66-72. [DOI: 10.1016/j.jbiomech.2015.11.022] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2014] [Revised: 09/30/2015] [Accepted: 11/15/2015] [Indexed: 10/22/2022]
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72
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Rode C, Sutedja Y, Kilbourne BM, Blickhan R, Andrada E. Minimizing the cost of locomotion with inclined trunk predicts crouched leg kinematics of small birds at realistic levels of elastic recoil. ACTA ACUST UNITED AC 2015; 219:485-90. [PMID: 26643087 DOI: 10.1242/jeb.127910] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 11/17/2015] [Indexed: 11/20/2022]
Abstract
Small birds move with pronograde trunk orientation and crouched legs. Although the pronograde trunk has been suggested to be beneficial for grounded running, the cause(s) of the specific leg kinematics are unknown. Here we show that three charadriiform bird species (northern lapwing, oystercatcher, and avocet; great examples of closely related species that differ remarkably in their hind limb design) move their leg segments during stance in a way that minimizes the cost of locomotion. We imposed measured trunk motions and ground reaction forces on a kinematic model of the birds. The model was used to search for leg configurations that minimize leg work that accounts for two factors: elastic recoil in the intertarsal joint, and cheaper negative muscle work relative to positive muscle work. A physiological level of elasticity (∼ 0.6) yielded segment motions that match the experimental data best, with a root mean square of angular deviations of ∼ 2.1 deg. This finding suggests that the exploitation of elastic recoil shapes the crouched leg kinematics of small birds under the constraint of pronograde trunk motion. Considering that an upright trunk and more extended legs likely decrease the cost of locomotion, our results imply that the cost of locomotion is a secondary movement criterion for small birds. Scaling arguments suggest that our approach may be utilized to provide new insights into the motion of extinct species such as dinosaurs.
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Affiliation(s)
- Christian Rode
- Department of Motion Science, Institute of Sport Science, Friedrich-Schiller-University Jena, Jena 07749, Germany
| | - Yefta Sutedja
- Department of Motion Science, Institute of Sport Science, Friedrich-Schiller-University Jena, Jena 07749, Germany
| | - Brandon M Kilbourne
- Institute of Systematic Zoology and Evolutionary Biology with Phyletic Museum, Friedrich-Schiller-University Jena, Jena 07743, Germany College for Life Sciences, Wissenschaftskolleg zu Berlin, Wallotstraße 19, Berlin 19143, Germany
| | - Reinhard Blickhan
- Department of Motion Science, Institute of Sport Science, Friedrich-Schiller-University Jena, Jena 07749, Germany
| | - Emanuel Andrada
- Department of Motion Science, Institute of Sport Science, Friedrich-Schiller-University Jena, Jena 07749, Germany Institute of Systematic Zoology and Evolutionary Biology with Phyletic Museum, Friedrich-Schiller-University Jena, Jena 07743, Germany
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73
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Gordon JC, Rankin JW, Daley MA. How do treadmill speed and terrain visibility influence neuromuscular control of guinea fowl locomotion? ACTA ACUST UNITED AC 2015; 218:3010-22. [PMID: 26254324 PMCID: PMC4631773 DOI: 10.1242/jeb.104646] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 07/21/2015] [Indexed: 12/28/2022]
Abstract
Locomotor control mechanisms must flexibly adapt to both anticipated and unexpected terrain changes to maintain movement and avoid a fall. Recent studies revealed that ground birds alter movement in advance of overground obstacles, but not treadmill obstacles, suggesting context-dependent shifts in the use of anticipatory control. We hypothesized that differences between overground and treadmill obstacle negotiation relate to differences in visual sensory information, which influence the ability to execute anticipatory manoeuvres. We explored two possible explanations: (1) previous treadmill obstacles may have been visually imperceptible, as they were low contrast to the tread, and (2) treadmill obstacles are visible for a shorter time compared with runway obstacles, limiting time available for visuomotor adjustments. To investigate these factors, we measured electromyographic activity in eight hindlimb muscles of the guinea fowl (Numida meleagris, N=6) during treadmill locomotion at two speeds (0.7 and 1.3 m s−1) and three terrain conditions at each speed: (i) level, (ii) repeated 5 cm low-contrast obstacles (<10% contrast, black/black), and (iii) repeated 5 cm high-contrast obstacles (>90% contrast, black/white). We hypothesized that anticipatory changes in muscle activity would be higher for (1) high-contrast obstacles and (2) the slower treadmill speed, when obstacle viewing time is longer. We found that treadmill speed significantly influenced obstacle negotiation strategy, but obstacle contrast did not. At the slower speed, we observed earlier and larger anticipatory increases in muscle activity and shifts in kinematic timing. We discuss possible visuomotor explanations for the observed context-dependent use of anticipatory strategies. Summary: Guinea fowl (Numida meleagris) show speed-dependent shifts in neuromuscular control during obstacle negotiation, characterized by a greater reliance on anticipatory modulation and stride-to-stride neural adjustments at slow speed, shifting towards feedforward activation and intrinsic mechanical stability at high speed.
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Affiliation(s)
- Joanne C Gordon
- Structure and Motion Laboratory, Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire AL9 7TA, UK
| | - Jeffery W Rankin
- Structure and Motion Laboratory, Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire AL9 7TA, UK
| | - Monica A Daley
- Structure and Motion Laboratory, Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire AL9 7TA, UK
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74
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Birn-Jeffery AV, Hubicki CM, Blum Y, Renjewski D, Hurst JW, Daley MA. Don't break a leg: running birds from quail to ostrich prioritise leg safety and economy on uneven terrain. ACTA ACUST UNITED AC 2015; 217:3786-96. [PMID: 25355848 PMCID: PMC4213177 DOI: 10.1242/jeb.102640] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Cursorial ground birds are paragons of bipedal running that span a 500-fold mass range from quail to ostrich. Here we investigate the task-level control priorities of cursorial birds by analysing how they negotiate single-step obstacles that create a conflict between body stability (attenuating deviations in body motion) and consistent leg force–length dynamics (for economy and leg safety). We also test the hypothesis that control priorities shift between body stability and leg safety with increasing body size, reflecting use of active control to overcome size-related challenges. Weight-support demands lead to a shift towards straighter legs and stiffer steady gait with increasing body size, but it remains unknown whether non-steady locomotor priorities diverge with size. We found that all measured species used a consistent obstacle negotiation strategy, involving unsteady body dynamics to minimise fluctuations in leg posture and loading across multiple steps, not directly prioritising body stability. Peak leg forces remained remarkably consistent across obstacle terrain, within 0.35 body weights of level running for obstacle heights from 0.1 to 0.5 times leg length. All species used similar stance leg actuation patterns, involving asymmetric force–length trajectories and posture-dependent actuation to add or remove energy depending on landing conditions. We present a simple stance leg model that explains key features of avian bipedal locomotion, and suggests economy as a key priority on both level and uneven terrain. We suggest that running ground birds target the closely coupled priorities of economy and leg safety as the direct imperatives of control, with adequate stability achieved through appropriately tuned intrinsic dynamics.
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Affiliation(s)
- Aleksandra V Birn-Jeffery
- Structure and Motion Laboratory, Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire AL9 7TA, UK
| | - Christian M Hubicki
- Dynamic Robotics Laboratory, Oregon State University, 204 Rogers Hall, Corvallis, OR 97331, USA
| | - Yvonne Blum
- Structure and Motion Laboratory, Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire AL9 7TA, UK
| | - Daniel Renjewski
- Dynamic Robotics Laboratory, Oregon State University, 204 Rogers Hall, Corvallis, OR 97331, USA
| | - Jonathan W Hurst
- Dynamic Robotics Laboratory, Oregon State University, 204 Rogers Hall, Corvallis, OR 97331, USA
| | - Monica A Daley
- Structure and Motion Laboratory, Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire AL9 7TA, UK
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75
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Voloshina AS, Ferris DP. Biomechanics and energetics of running on uneven terrain. J Exp Biol 2015; 218:711-9. [DOI: 10.1242/jeb.106518] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
ABSTRACT
In the natural world, legged animals regularly run across uneven terrain with remarkable ease. To gain understanding of how running on uneven terrain affects the biomechanics and energetics of locomotion, we studied human subjects (N=12) running at 2.3 m s−1 on an uneven terrain treadmill, with up to a 2.5 cm height variation. We hypothesized that running on uneven terrain would show increased energy expenditure, step parameter variability and leg stiffness compared with running on smooth terrain. Subject energy expenditure increased by 5% (0.68 W kg−1; P<0.05) when running on uneven terrain compared with smooth terrain. Step width and length variability also increased by 27% and 26%, respectively (P<0.05). Positive and negative ankle work decreased on uneven terrain by 22% (0.413 J kg−1) and 18% (0.147 J kg−1), respectively (P=0.0001 and P=0.0008). Mean muscle activity increased on uneven terrain for three muscles in the thigh (P<0.05). Leg stiffness also increased by 20% (P<0.05) during running on uneven terrain compared with smooth terrain. Calculations of gravitational potential energy fluctuations suggest that about half of the energetic increases can be explained by additional positive and negative mechanical work for up and down steps on the uneven surface. This is consistent between walking and running, as the absolute increases in energetic cost for walking and running on uneven terrain were similar: 0.68 and 0.48 W kg−1, respectively. These results provide insight into how surface smoothness can affect locomotion biomechanics and energetics in the real world.
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Affiliation(s)
- Alexandra S. Voloshina
- School of Kinesiology, University of Michigan, Ann Arbor, MI, USA
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Daniel P. Ferris
- School of Kinesiology, University of Michigan, Ann Arbor, MI, USA
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76
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Abstract
One of the key topics in robotics is legged locomotion, taking inspiration from walking and bouncing gaits of bipeds and quadrupeds. A fundamental tool for analyzing running and hopping is the spring loaded inverted pendulum (SLIP), thanks to its simplicity but also effectiveness in modeling bouncing gaits. Being completely passive, the SLIP model does not have the ability to modify its net energy, which, for example, can be a prohibitive obstacle when traveling on a terrain with varying heights. The actuated version of the SLIP model, the active SLIP, considered in this paper, includes a series actuator that allows energy variations via compressing or extending the spring. In this work, we investigate how different actuator motions can affect the system’s state, and we propose a control strategy, based on graphical and numerical studies of the reachability space, and updated throughout the stance phase, to drive the system to a desired state. We quantify its performance benefits, particularly in serving as an error-recovering method. The objective of our control strategy is not to replace any leg-placement approach proposed by other works, but rather to be paired with any other leg-placement or path planning method. Its main advantage is the ability to reduce the effects of sensing errors and disturbances happening at landing as well as during the stance phase.
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Affiliation(s)
- Giulia Piovan
- Robotics Laboratory, University of California at Santa Barbara, CA, USA
| | - Katie Byl
- Robotics Laboratory, University of California at Santa Barbara, CA, USA
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77
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Andrada E, Rode C, Sutedja Y, Nyakatura JA, Blickhan R. Trunk orientation causes asymmetries in leg function in small bird terrestrial locomotion. Proc Biol Sci 2014; 281:20141405. [PMID: 25377449 PMCID: PMC4240980 DOI: 10.1098/rspb.2014.1405] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Accepted: 10/07/2014] [Indexed: 01/22/2023] Open
Abstract
In contrast to the upright trunk in humans, trunk orientation in most birds is almost horizontal (pronograde). It is conceivable that the orientation of the heavy trunk strongly influences the dynamics of bipedal terrestrial locomotion. Here, we analyse for the first time the effects of a pronograde trunk orientation on leg function and stability during bipedal locomotion. For this, we first inferred the leg function and trunk control strategy applied by a generalized small bird during terrestrial locomotion by analysing synchronously recorded kinematic (three-dimensional X-ray videography) and kinetic (three-dimensional force measurement) quail locomotion data. Then, by simulating quail gaits using a simplistic bioinspired numerical model which made use of parameters obtained in in vivo experiments with real quail, we show that the observed asymmetric leg function (left-skewed ground reaction force and longer leg at touchdown than at lift-off) is necessary for pronograde steady-state locomotion. In addition, steady-state locomotion becomes stable for specific morphological parameters. For quail-like parameters, the most common stable solution is grounded running, a gait preferred by quail and most of the other small birds. We hypothesize that stability of bipedal locomotion is a functional demand that, depending on trunk orientation and centre of mass location, constrains basic hind limb morphology and function, such as leg length, leg stiffness and leg damping.
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Affiliation(s)
- Emanuel Andrada
- Science of Motion, Friedrich-Schiller University Jena, Seidelstraße 20, 07749 Jena, Germany
| | - Christian Rode
- Science of Motion, Friedrich-Schiller University Jena, Seidelstraße 20, 07749 Jena, Germany
| | - Yefta Sutedja
- Science of Motion, Friedrich-Schiller University Jena, Seidelstraße 20, 07749 Jena, Germany
| | - John A Nyakatura
- Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich-Schiller-Universität, 07743 Jena, Germany Image Knowledge Gestaltung: an interdisciplinary laboratory and Institute of Biology, Humboldt-University, Philippstraße 13, 11015 Berlin, Germany
| | - Reinhard Blickhan
- Science of Motion, Friedrich-Schiller University Jena, Seidelstraße 20, 07749 Jena, Germany
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78
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Ernst M, Götze M, Müller R, Blickhan R. Vertical adaptation of the center of mass in human running on uneven ground. Hum Mov Sci 2014; 38:293-304. [PMID: 25457426 DOI: 10.1016/j.humov.2014.05.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 03/31/2014] [Accepted: 05/15/2014] [Indexed: 11/18/2022]
Abstract
In running we are frequently confronted with different kinds of disturbances. Some require quick reactions and adaptations while others, like moderate changes in ground level, can be compensated passively. Monitoring the kinematics of the runner's center of mass (CoM) in such situations can reveal what global locomotion control strategies humans use and can help to distinguish between active and passive compensation methods. In this study single and permanent upward steps of 10 cm as well as drops of the same height were used as mechanical disturbances and the adaptations in the vertical oscillation of the runners CoM were analyzed. We found that runners visually perceiving uneven ground ahead substantially adapted their CoM in preparation by lifting it about 50% of step height or lowering it by about 40% of drop height, respectively. After contact on the changed ground level different adaptations depending on the situation occur. For persisting changes the adaptation to the elevated ground is completed after the first step on the new level. For single steps part of the adaptation takes place while returning to the ground. The consistent adaptations for the different situations support the idea that controlling the CoM by adapting leg parameters is a general control principle in running.
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Affiliation(s)
- M Ernst
- Motion Science, Institute of Sport Science, Friedrich Schiller University Jena, Seidelstrasse 20, 07749 Jena, Germany; Institute of Solid Mechanics, Faculty of Mechanical Engineering, Technische Universität Braunschweig, Schleinitzstrasse 20, 38106 Braunschweig, Germany.
| | - M Götze
- Motion Science, Institute of Sport Science, Friedrich Schiller University Jena, Seidelstrasse 20, 07749 Jena, Germany
| | - R Müller
- Motion Science, Institute of Sport Science, Friedrich Schiller University Jena, Seidelstrasse 20, 07749 Jena, Germany
| | - R Blickhan
- Motion Science, Institute of Sport Science, Friedrich Schiller University Jena, Seidelstrasse 20, 07749 Jena, Germany
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79
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Paxton H, Tickle PG, Rankin JW, Codd JR, Hutchinson JR. Anatomical and biomechanical traits of broiler chickens across ontogeny. Part II. Body segment inertial properties and muscle architecture of the pelvic limb. PeerJ 2014; 2:e473. [PMID: 25071996 PMCID: PMC4103074 DOI: 10.7717/peerj.473] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 06/16/2014] [Indexed: 11/24/2022] Open
Abstract
In broiler chickens, genetic success for desired production traits is often shadowed by welfare concerns related to musculoskeletal health. Whilst these concerns are clear, a viable solution is still elusive. Part of the solution lies in knowing how anatomical changes in afflicted body systems that occur across ontogeny influence standing and moving. Here, to demonstrate these changes we quantify the segment inertial properties of the whole body, trunk (legs removed) and the right pelvic limb segments of five broilers at three different age groups across development. We also consider how muscle architecture (mass, fascicle length and other properties related to mechanics) changes for selected muscles of the pelvic limb. All broilers used had no observed lameness, but we document the limb pathologies identified post mortem, since these two factors do not always correlate, as shown here. The most common leg disorders, including bacterial chondronecrosis with osteomyelitis and rotational and angular deformities of the lower limb, were observed in chickens at all developmental stages. Whole limb morphology is not uniform relative to body size, with broilers obtaining large thighs and feet between four and six weeks of age. This implies that the energetic cost of swinging the limbs is markedly increased across this growth period, perhaps contributing to reduced activity levels. Hindlimb bone length does not change during this period, which may be advantageous for increased stability despite the increased energetic costs. Increased pectoral muscle growth appears to move the centre of mass cranio-dorsally in the last two weeks of growth. This has direct consequences for locomotion (potentially greater limb muscle stresses during standing and moving). Our study is the first to measure these changes in the musculoskeletal system across growth in chickens, and reveals how artificially selected changes of the morphology of the pectoral apparatus may cause deficits in locomotion.
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Affiliation(s)
- Heather Paxton
- Structure & Motion Laboratory, Department of Comparative Biomedical Sciences, The Royal Veterinary College, University of London, Hatfield, Hertfordshire, UK
| | - Peter G. Tickle
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - Jeffery W. Rankin
- Structure & Motion Laboratory, Department of Comparative Biomedical Sciences, The Royal Veterinary College, University of London, Hatfield, Hertfordshire, UK
| | - Jonathan R. Codd
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - John R. Hutchinson
- Structure & Motion Laboratory, Department of Comparative Biomedical Sciences, The Royal Veterinary College, University of London, Hatfield, Hertfordshire, UK
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80
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Blum Y, Vejdani HR, Birn-Jeffery AV, Hubicki CM, Hurst JW, Daley MA. Swing-leg trajectory of running guinea fowl suggests task-level priority of force regulation rather than disturbance rejection. PLoS One 2014; 9:e100399. [PMID: 24979750 PMCID: PMC4076256 DOI: 10.1371/journal.pone.0100399] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 05/27/2014] [Indexed: 11/23/2022] Open
Abstract
To achieve robust and stable legged locomotion in uneven terrain, animals must effectively coordinate limb swing and stance phases, which involve distinct yet coupled dynamics. Recent theoretical studies have highlighted the critical influence of swing-leg trajectory on stability, disturbance rejection, leg loading and economy of walking and running. Yet, simulations suggest that not all these factors can be simultaneously optimized. A potential trade-off arises between the optimal swing-leg trajectory for disturbance rejection (to maintain steady gait) versus regulation of leg loading (for injury avoidance and economy). Here we investigate how running guinea fowl manage this potential trade-off by comparing experimental data to predictions of hypothesis-based simulations of running over a terrain drop perturbation. We use a simple model to predict swing-leg trajectory and running dynamics. In simulations, we generate optimized swing-leg trajectories based upon specific hypotheses for task-level control priorities. We optimized swing trajectories to achieve i) constant peak force, ii) constant axial impulse, or iii) perfect disturbance rejection (steady gait) in the stance following a terrain drop. We compare simulation predictions to experimental data on guinea fowl running over a visible step down. Swing and stance dynamics of running guinea fowl closely match simulations optimized to regulate leg loading (priorities i and ii), and do not match the simulations optimized for disturbance rejection (priority iii). The simulations reinforce previous findings that swing-leg trajectory targeting disturbance rejection demands large increases in stance leg force following a terrain drop. Guinea fowl negotiate a downward step using unsteady dynamics with forward acceleration, and recover to steady gait in subsequent steps. Our results suggest that guinea fowl use swing-leg trajectory consistent with priority for load regulation, and not for steadiness of gait. Swing-leg trajectory optimized for load regulation may facilitate economy and injury avoidance in uneven terrain.
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Affiliation(s)
- Yvonne Blum
- Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, Hertfordshire, United Kingdom
| | - Hamid R. Vejdani
- Mechanical, Industrial and Manufacturing Engineering, Oregon State University, Corvallis, Oregon, United States of America
| | - Aleksandra V. Birn-Jeffery
- Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, Hertfordshire, United Kingdom
- Department of Biology, University of California Riverside, Riverside, California, United States of America
| | - Christian M. Hubicki
- Mechanical, Industrial and Manufacturing Engineering, Oregon State University, Corvallis, Oregon, United States of America
| | - Jonathan W. Hurst
- Mechanical, Industrial and Manufacturing Engineering, Oregon State University, Corvallis, Oregon, United States of America
| | - Monica A. Daley
- Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, Hertfordshire, United Kingdom
- * E-mail:
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81
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Stahl VA, Nichols TR. Short-term effect of crural fasciotomy on kinematic variability and propulsion during level locomotion. J Mot Behav 2014; 46:339-49. [PMID: 24914468 DOI: 10.1080/00222895.2014.914885] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Treadmill locomotion can be characterized by consistent step-to-step kinematics despite the redundant degrees of freedom. The authors investigated the effect of disrupting the crural fascia in decerebrate cats to determine if the crural fascia contributed to kinematic variability and propulsion in the limb. Crural fasciotomy resulted in statistically significant decreases in velocity and acceleration in the joint angles during level walking, before, during, and after paw-off, particularly at the ankle. A further finding was an increase in variance of the limb segment trajectories in the frontal plane. The crural fascia therefore provides force transmission and reduction in kinematic variability to the limb during locomotion.
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Affiliation(s)
- V A Stahl
- a School of Applied Physiology, Georgia Institute of Technology , Atlanta
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82
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Kambic RE, Roberts TJ, Gatesy SM. Long-axis rotation: a missing degree of freedom in avian bipedal locomotion. J Exp Biol 2014; 217:2770-82. [DOI: 10.1242/jeb.101428] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Abstract
Ground-dwelling birds are typically characterized as erect bipeds having hind limbs that operate parasagittally. Consequently, most previous research has emphasized flexion/extension angles and moments as calculated from a lateral perspective. Three-dimensional motion analyses have documented non-planar limb movements, but the skeletal kinematics underlying changes in foot orientation and transverse position remain unclear. In particular, long-axis rotation of the proximal limb segments is extremely difficult to measure with topical markers. Here we present six degree of freedom skeletal kinematic data from maneuvering guineafowl acquired by marker-based XROMM (X-ray Reconstruction of Moving Morphology). Translations and rotations of the hips, knees, ankles, and pelvis were derived from animated bone models using explicit joint coordinate systems. We distinguished sidesteps, sidestep yaws, crossover yaws, sidestep turns, and crossover turns, but birds often performed a sequence of blended partial maneuvers. Long-axis rotation of the femur (up to 38°) modulated the foot's transverse position. Long-axis rotation of the tibiotarsus (up to 65°) also affected medio-lateral positioning, but primarily served to either reorient a swing phase foot or yaw the body about a stance phase foot. Tarsometatarsal long-axis rotation was minimal, as was hip, knee, and ankle abduction/adduction. Despite having superficially hinge-like joints, birds coordinate substantial long-axis rotations of the hips and knees to execute complex 3-D maneuvers while striking a diversity of non-planar poses.
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83
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Joint-specific changes in locomotor complexity in the absence of muscle atrophy following incomplete spinal cord injury. J Neuroeng Rehabil 2013; 10:97. [PMID: 23947694 PMCID: PMC3765129 DOI: 10.1186/1743-0003-10-97] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 07/26/2013] [Indexed: 12/23/2022] Open
Abstract
Background Following incomplete spinal cord injury (iSCI), descending drive is impaired, possibly leading to a decrease in the complexity of gait. To test the hypothesis that iSCI impairs gait coordination and decreases locomotor complexity, we collected 3D joint angle kinematics and muscle parameters of rats with a sham or an incomplete spinal cord injury. Methods 12 adult, female, Long-Evans rats, 6 sham and 6 mild-moderate T8 iSCI, were tested 4 weeks following injury. The Basso Beattie Bresnahan locomotor score was used to verify injury severity. Animals had reflective markers placed on the bony prominences of their limb joints and were filmed in 3D while walking on a treadmill. Joint angles and segment motion were analyzed quantitatively, and complexity of joint angle trajectory and overall gait were calculated using permutation entropy and principal component analysis, respectively. Following treadmill testing, the animals were euthanized and hindlimb muscles removed. Excised muscles were tested for mass, density, fiber length, pennation angle, and relaxed sarcomere length. Results Muscle parameters were similar between groups with no evidence of muscle atrophy. The animals showed overextension of the ankle, which was compensated for by a decreased range of motion at the knee. Left-right coordination was altered, leading to left and right knee movements that are entirely out of phase, with one joint moving while the other is stationary. Movement patterns remained symmetric. Permutation entropy measures indicated changes in complexity on a joint specific basis, with the largest changes at the ankle. No significant difference was seen using principal component analysis. Rats were able to achieve stable weight bearing locomotion at reasonable speeds on the treadmill despite these deficiencies. Conclusions Decrease in supraspinal control following iSCI causes a loss of complexity of ankle kinematics. This loss can be entirely due to loss of supraspinal control in the absence of muscle atrophy and may be quantified using permutation entropy. Joint-specific differences in kinematic complexity may be attributed to different sources of motor control. This work indicates the importance of the ankle for rehabilitation interventions following spinal cord injury.
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84
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Andrada E, Rode C, Blickhan R. Grounded running in quails: simulations indicate benefits of observed fixed aperture angle between legs before touch-down. J Theor Biol 2013; 335:97-107. [PMID: 23831138 DOI: 10.1016/j.jtbi.2013.06.031] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 06/14/2013] [Accepted: 06/25/2013] [Indexed: 11/26/2022]
Abstract
Many birds use grounded running (running without aerial phases) in a wide range of speeds. Contrary to walking and running, numerical investigations of this gait based on the BSLIP (bipedal spring loaded inverted pendulum) template are rare. To obtain template related parameters of quails (e.g. leg stiffness) we used x-ray cinematography combined with ground reaction force measurements of quail grounded running. Interestingly, with speed the quails did not adjust the swing leg's angle of attack with respect to the ground but adapted the angle between legs (which we termed aperture angle), and fixed it about 30ms before touchdown. In simulations with the BSLIP we compared this swing leg alignment policy with the fixed angle of attack with respect to the ground typically used in the literature. We found symmetric periodic grounded running in a simply connected subset comprising one third of the investigated parameter space. The fixed aperture angle strategy revealed improved local stability and surprising tolerance with respect to large perturbations. Starting with the periodic solutions, after step-down step-up or step-up step-down perturbations of 10% leg rest length, in the vast majority of cases the bipedal SLIP could accomplish at least 50 steps to fall. The fixed angle of attack strategy was not feasible. We propose that, in small animals in particular, grounded running may be a common gait that allows highly compliant systems to exploit energy storage without the necessity of quick changes in the locomotor program when facing perturbations.
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Affiliation(s)
- Emanuel Andrada
- Science of Motion, Friedrich-Schiller University Jena, Seidelstr. 20, 07749 Jena, Germany.
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85
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Maes L, Abourachid A. Gait transitions and modular organization of mammal locomotion. ACTA ACUST UNITED AC 2013; 216:2257-65. [PMID: 23531814 DOI: 10.1242/jeb.082149] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Quadrupedal locomotion is the result of complex interactions between biomechanical and neural systems. During steady gaits, both systems are in stable states. When the animal changes its speed, transitions between gaits can occur in which the different coordination parameters are dissociated. Consequently, transitions are the periods where it is possible to detect and identify those parameters involved in the mechanical or neural control of locomotion. We studied interlimb coordination using a sequential method (antero-posterior sequence) to measure the footfall patterns of dogs when accelerating and decelerating from 1.5 m s(-1) to more than 6 m s(-1) and back. We obtained 383 transitions between all the symmetrical and asymmetrical gaits used by the dogs. Analysis of the interlimb coordination modifications and of each foot parameter showed that mechanics drive the stance phase whereas coordination is controlled during the swing phase. Furthermore, comparison of the transition patterns between all gaits reveals the modular organization of locomotion: a pectoral module coordinates the two forelimbs, a pelvic module coordinates the two hindlimbs and an axial module coordinates the two pairs of limbs and the trunk motion. The three modules cooperate to give rise to a template of stable interlimb coordination pattern, such as walk, trot or gallop.
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Affiliation(s)
- Ludovic Maes
- Muséum National d'Histoire Naturelle-CNRS, Département EGB, UMR7179, Pavillon d'Anatomie Comparée, 55 Rue Buffon, 75231 Paris Cedex 05, France
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86
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Franz JR, Kram R. How does age affect leg muscle activity/coactivity during uphill and downhill walking? Gait Posture 2013; 37:378-84. [PMID: 22940542 PMCID: PMC3538118 DOI: 10.1016/j.gaitpost.2012.08.004] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 06/21/2012] [Accepted: 08/07/2012] [Indexed: 02/02/2023]
Abstract
Walking uphill and downhill can be challenging for community-dwelling old adults. We investigated the effects of age on leg muscle activity amplitudes and timing during level, uphill, and downhill walking. We hypothesized that old adults would exhibit smaller increases in ankle extensor muscle activities and greater increases in hip extensor muscle activities compared to young adults during uphill vs. level walking. We also hypothesized that, compared to level walking, antagonist leg muscle coactivation would be disproportionately greater in old vs. young adults during downhill walking. Ten old (72±5yrs) and ten young (25±4yrs) subjects walked at 1.25m/s on a treadmill at seven grades (0°, ±3°, ±6°, ±9°). We quantified the stance phase electromyographic activities of the gluteus maximus (GMAX), biceps femoris (BF), rectus femoris (RF), vastus medialis (VM), medial gastrocnemius (MG), soleus (SOL), and tibialis anterior (TA). Old adults exhibited smaller increases in MG activity with steeper uphill grade than young adults (e.g., +136% vs. +174% at 9°). A disproportionate recruitment of hip muscles led to GMAX activity approaching the maximum isometric capacity of these active old adults at steep uphill grades (e.g., old vs. young, 73% MVC vs. 33% MVC at +9°). Neither uphill nor downhill walking affected the greater coactivation of antagonist muscles in old vs. young adults. We conclude that the disproportionate recruitment of hip muscles with advanced age may have critical implications for maintaining independent mobility in old adults, particularly at steeper uphill grades.
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Affiliation(s)
- Jason R Franz
- Department of Integrative Physiology, University of Colorado, Boulder, CO 80309, United States.
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87
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Paxton H, Daley M, Corr S, Hutchinson J. The gait dynamics of the modern broiler chicken: A cautionary tale of selective breeding. J Exp Biol 2013; 216:3237-48. [DOI: 10.1242/jeb.080309] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Summary
One of the most extraordinary results of selective breeding is the modern broiler chicken, whose phenotypic attributes reflect its genetic success. Unfortunately, leg health issues and poor walking ability are prevalent in the broiler population, with the exact aetiopathogenesis unknown. Here we present a biomechanical analysis of the gait dynamics of the modern broiler and its two pureline commercial broiler breeder lines (A and B) in order to clarify how changes in basic morphology are associated with the way these chickens walk. We collected force plate and kinematic data from 25 chickens (market age), over a range of walking speeds, to quantify the 3D dynamics of the centre of mass (CoM) and determine how these birds modulate the force and mechanical work of locomotion. Common features of their gait include extremely slow walking speeds, a wide base of support and large lateral motions of the CoM, which primarily reflect changes to cope with their apparent instability and large body mass. These features allowed the chickens to keep their peak vertical forces low, but resulted in high mediolateral forces, which exceeded fore-aft forces. Gait differences directly related to morphological characteristics also exist. This was particularly evident in pureline B birds, which have a more crouched limb posture. Mechanical costs of transport were still similar across all lines and were not exceptional when compared to more wild-type ground-running birds. Broiler chickens seem to have an awkward gait, but some aspects of their dynamics show rather surprising similarities to other avian bipeds.
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88
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Andrada E, Nyakatura JA, Bergmann F, Blickhan R. Adjustments of global and hindlimb local properties during the terrestrial locomotion of the common quail (Coturnix coturnix). J Exp Biol 2013; 216:3906-16. [DOI: 10.1242/jeb.085399] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Summary
Increasing insight into neuro-mechanical control strategies during perturbed locomotion is gained. In contrast, more general analyses on simple model (template) related parameters during avian terrestrial locomotion are still rare. Quails kinematic data obtained using X-ray videography combined with ground reaction force measurements were used as a basis to investigate how "global" template and "local" leg joint parameters in this small predominantly terrestrial bird change with speed and gait. Globally, quail locomotion approximates a spring-like behavior in all investigated gaits. However, ground reaction forces are more vertically oriented which may help to balance the trunk. At the joint level, practically all the spring like work was found to occur in the ITJ (intertarsal joint). From walking to grounded running the local stiffness of the ITJ decreases similarly to the reduction observed in global leg stiffness. Thus, in gaits without aerial phases the quails may modulate ITJ stiffness to regulate global leg stiffness, and therefore gait changes, to a significant degree. At higher speeds leg compression and leg stiffness are increased (the latter to values not significantly different to those obtained during walking). This enables the animals to shorten contact time and to generate aerial phases (running). However, we did not observe a change in the stiffness in the ITJ with a change of gait from grounded running to running. We hypothesize that a more extended leg at touch-down, controlled by the joint angles in knee and ITJ, has an important influence in the leg stiffness adjustment process during running.
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89
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Qiao M, Jindrich DL. Task-level strategies for human sagittal-plane running maneuvers are consistent with robotic control policies. PLoS One 2012; 7:e51888. [PMID: 23284804 PMCID: PMC3527458 DOI: 10.1371/journal.pone.0051888] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 11/12/2012] [Indexed: 11/26/2022] Open
Abstract
The strategies that humans use to control unsteady locomotion are not well understood. A “spring-mass” template comprised of a point mass bouncing on a sprung leg can approximate both center of mass movements and ground reaction forces during running in humans and other animals. Legged robots that operate as bouncing, “spring-mass” systems can maintain stable motion using relatively simple, distributed feedback rules. We tested whether the changes to sagittal-plane movements during five running tasks involving active changes to running height, speed, and orientation were consistent with the rules used by bouncing robots to maintain stability. Changes to running height were associated with changes to leg force but not stance duration. To change speed, humans primarily used a “pogo stick” strategy, where speed changes were associated with adjustments to fore-aft foot placement, and not a “unicycle” strategy involving systematic changes to stance leg hip moment. However, hip moments were related to changes to body orientation and angular speed. Hip moments could be described with first order proportional-derivative relationship to trunk pitch. Overall, the task-level strategies used for body control in humans were consistent with the strategies employed by bouncing robots. Identification of these behavioral strategies could lead to a better understanding of the sensorimotor mechanisms that allow for effective unsteady locomotion.
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Affiliation(s)
- Mu Qiao
- Kinesiology Program, School of Nutrition and Health Promotion, Arizona State University, Tempe, Arizona, United States of America
| | - Devin L. Jindrich
- Department of Kinesiology, California State University San Marcos, San Marcos, California, United States of America
- * E-mail:
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90
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Ernst M, Geyer H, Blickhan R. Extension and customization of self-stability control in compliant legged systems. BIOINSPIRATION & BIOMIMETICS 2012; 7:046002. [PMID: 22791685 DOI: 10.1088/1748-3182/7/4/046002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Several recent studies on the control of legged locomotion in animal and robot running focus on the influence of different leg parameters on gait stability. In a preceding investigation self-stability controls showing deadbeat behavior could be obtained by studying the dynamics of the system in dependence of the leg orientation carefully adjusted during the flight phase. Such controls allow to accommodate disturbances of the ground level without having to detect them. Here we further this method in two ways. Besides the leg orientation, we allow changes in leg stiffness during flight and show that this extension substantially improves the rejection of ground disturbances. In a human like example the tolerance of random variation in ground level over many steps increased from 3.5% to 35% of leg length. In single steps changes of about 70% leg length (either up or down) could be negotiated. The variable leg stiffness not only allows to start with flat leg orientations maximizing step tolerances but also increase the control subspace. This allows to customize self-stability controls and to consider physical and technical limitations found in animals and robots.
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Affiliation(s)
- M Ernst
- Science of Motion, Institute of Sport Science, Friedrich-Schiller University, Seidelstrasse 20, 07749 Jena, Germany.
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91
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Nyakatura J, Andrada E, Grimm N, Weise H, Fischer M. Kinematics and Center of Mass Mechanics During Terrestrial Locomotion in Northern Lapwings (Vanellus vanellus, Charadriiformes). ACTA ACUST UNITED AC 2012; 317:580-94. [DOI: 10.1002/jez.1750] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 07/02/2012] [Accepted: 07/10/2012] [Indexed: 11/09/2022]
Affiliation(s)
- J.A. Nyakatura
- Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum; Friedrich-Schiller-Universität Jena; Jena; Germany
| | - E. Andrada
- Institut für Sportwissenschaft; Friedrich-Schiller-Universität Jena; Jena; Germany
| | - N. Grimm
- Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum; Friedrich-Schiller-Universität Jena; Jena; Germany
| | - H. Weise
- Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum; Friedrich-Schiller-Universität Jena; Jena; Germany
| | - M.S. Fischer
- Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum; Friedrich-Schiller-Universität Jena; Jena; Germany
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92
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Birn-Jeffery AV, Daley MA. Birds achieve high robustness in uneven terrain through active control of landing conditions. J Exp Biol 2012; 215:2117-27. [DOI: 10.1242/jeb.065557] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
We understand little about how animals adjust locomotor behaviour to negotiate uneven terrain. The mechanical demands and constraints of such behaviours likely differ from uniform terrain locomotion. Here we investigated how common pheasants negotiate visible obstacles with heights from 10 to 50% of leg length. Our goal was to determine the neuro-mechanical strategies used to achieve robust stability, and address whether strategies vary with obstacle height. We found that control of landing conditions was crucial for minimising fluctuations in stance leg loading and work in uneven terrain. Variation in touchdown leg angle (θTD) was correlated with the orientation of ground force during stance, and the angle between the leg and body velocity vector at touchdown (βTD) was correlated with net limb work. Pheasants actively targeted obstacles to control body velocity and leg posture at touchdown to achieve nearly steady dynamics on the obstacle step. In the approach step to an obstacle, the birds produced net positive limb work to launch themselves upward. On the obstacle, body dynamics were similar to uniform terrain. Pheasants also increased swing leg retraction velocity during obstacle negotiation, which we suggest is an active strategy to minimise fluctuations in peak force and leg posture in uneven terrain. Thus, pheasants appear to achieve robustly stable locomotion through a combination of path planning using visual feedback and active adjustment of leg swing dynamics to control landing conditions. We suggest that strategies for robust stability are context specific, depending on the quality of sensory feedback available, especially visual input.
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Affiliation(s)
| | - Monica A. Daley
- The Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield AL9 7TA, UK
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93
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Scohier M, De Jaeger D, Schepens B. Adjustments after an ankle dorsiflexion perturbation during human running. Gait Posture 2012; 35:29-35. [PMID: 21872474 DOI: 10.1016/j.gaitpost.2011.07.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Revised: 03/25/2011] [Accepted: 07/28/2011] [Indexed: 02/02/2023]
Abstract
In this study we investigated the effect of a mechanical perturbation of unexpected timing during human running. With the use of a powered exoskeleton, we evoked a dorsiflexion of the right ankle during its swing phase while subjects ran on a treadmill. The perturbation resulted in an increase of the right ankle dorsiflexion of at least 5°. The first two as well as the next five steps after the perturbation were analyzed to observe the possible immediate and late biomechanical adjustments. In all cases subjects continued to run after the perturbation. The immediate adjustments were the greatest and the most frequent when the delay between the right ankle perturbation and the subsequent right foot touch-down was the shortest. For example, the vertical impact peak force was strongly modified on the first step after the perturbations and this adjustment was correlated to a right ankle angle still clearly modified at touch-down. Some late adjustments were observed in the subsequent steps predominantly occurring during left steps. Subjects maintained the step length and the step period as constant as possible by adjusting other step parameters in order to avoid stumbling and continue running at the speed imposed by the treadmill. To our knowledge, our experiments are the first to investigate perturbations of unexpected timing during human running. The results show that humans have a time-dependent, adapted strategy to maintain their running pattern.
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Affiliation(s)
- M Scohier
- Laboratoire de Physiologie et de Biomécanique de la Locomotion, Institute of NeuroScience, Université catholique de Louvain, Place Pierre de Coubertin 1, 1348 Louvain-la-Neuve, Belgium
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94
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Daley MA, Biewener AA. Leg muscles that mediate stability: mechanics and control of two distal extensor muscles during obstacle negotiation in the guinea fowl. Philos Trans R Soc Lond B Biol Sci 2011; 366:1580-91. [PMID: 21502128 DOI: 10.1098/rstb.2010.0338] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Here, we used an obstacle treadmill experiment to investigate the neuromuscular control of locomotion in uneven terrain. We measured in vivo function of two distal muscles of the guinea fowl, lateral gastrocnemius (LG) and digital flexor-IV (DF), during level running, and two uneven terrains, with 5 and 7 cm obstacles. Uneven terrain required one step onto an obstacle every four to five strides. We compared both perturbed and unperturbed strides in uneven terrain to level terrain. When the bird stepped onto an obstacle, the leg became crouched, both muscles acted at longer lengths and produced greater work, and body height increased. Muscle activation increased on obstacle strides in the LG, but not the DF, suggesting a greater reflex contribution to LG. In unperturbed strides in uneven terrain, swing pre-activation of DF increased by 5 per cent compared with level terrain, suggesting feed-forward tuning of leg impedance. Across conditions, the neuromechanical factors in work output differed between the two muscles, probably due to differences in muscle-tendon architecture. LG work depended primarily on fascicle length, whereas DF work depended on both length and velocity during loading. These distal muscles appear to play a critical role in stability by rapidly sensing and responding to altered leg-ground interaction.
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Affiliation(s)
- Monica A Daley
- Structure and Motion Laboratory, Royal Veterinary College, University of London, Hawskhead Lane, Hatfield, Hertfordshire AL9 7TA, UK.
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95
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Markowitz J, Krishnaswamy P, Eilenberg MF, Endo K, Barnhart C, Herr H. Speed adaptation in a powered transtibial prosthesis controlled with a neuromuscular model. Philos Trans R Soc Lond B Biol Sci 2011; 366:1621-31. [PMID: 21502131 DOI: 10.1098/rstb.2010.0347] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Control schemes for powered ankle-foot prostheses would benefit greatly from a means to make them inherently adaptive to different walking speeds. Towards this goal, one may attempt to emulate the intact human ankle, as it is capable of seamless adaptation. Human locomotion is governed by the interplay among legged dynamics, morphology and neural control including spinal reflexes. It has been suggested that reflexes contribute to the changes in ankle joint dynamics that correspond to walking at different speeds. Here, we use a data-driven muscle-tendon model that produces estimates of the activation, force, length and velocity of the major muscles spanning the ankle to derive local feedback loops that may be critical in the control of those muscles during walking. This purely reflexive approach ignores sources of non-reflexive neural drive and does not necessarily reflect the biological control scheme, yet can still closely reproduce the muscle dynamics estimated from biological data. The resulting neuromuscular model was applied to control a powered ankle-foot prosthesis and tested by an amputee walking at three speeds. The controller produced speed-adaptive behaviour; net ankle work increased with walking speed, highlighting the benefits of applying neuromuscular principles in the control of adaptive prosthetic limbs.
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Affiliation(s)
- Jared Markowitz
- Biomechatronics Group, Massachusetts Institute of Technology, 75 Amherst Street, Cambridge, MA 02139, USA
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Clark AJ, Higham TE. Slipping, sliding and stability: locomotor strategies for overcoming low-friction surfaces. ACTA ACUST UNITED AC 2011; 214:1369-78. [PMID: 21430214 DOI: 10.1242/jeb.051136] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Legged terrestrial animals must avoid falling while negotiating unexpected perturbations inherent to their structurally complex environments. Among humans, fatal and nonfatal injuries frequently result from slip-induced falls precipitated by sudden unexpected encounters with low-friction surfaces. Although studies using walking human models have identified some causes of falls and mechanisms underlying slip prevention, it is unclear whether these apply to various locomotor speeds and other species. We used high-speed video and inverse dynamics to investigate the locomotor biomechanics of helmeted guinea fowl traversing slippery surfaces at variable running speeds (1.3-3.6 m s(-1)). Falls were circumvented when limb contact angles exceeded 70 deg, though lower angles were tolerated at faster running speeds (>3.0 m s(-1)). These prerequisites permitted a forward shift of the body's center of mass over the limb's base of support, which kept slip distances below 10 cm (the threshold distance for falls) and maximized the vertical ground reaction forces, thus facilitating limb retraction and the conclusion of the stance phase. These postural control strategies for slip avoidance parallel those in humans, demonstrating the applicability of these strategies across locomotor gaits and the potential for guinea fowl as an insightful model for invasive approaches to understanding limb neuromuscular control on slippery surfaces.
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Affiliation(s)
- Andrew J Clark
- Department of Biological Sciences, Clemson University, 132 Long Hall, Clemson, SC 29634, USA.
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97
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Lee DV, Biewener AA. BigDog-Inspired Studies in the Locomotion of Goats and Dogs. Integr Comp Biol 2011; 51:190-202. [DOI: 10.1093/icb/icr061] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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98
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Sabatier MJ, To BN, Nicolini J, English AW. Effect of slope and sciatic nerve injury on ankle muscle recruitment and hindlimb kinematics during walking in the rat. ACTA ACUST UNITED AC 2011; 214:1007-16. [PMID: 21346129 DOI: 10.1242/jeb.051508] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Slope-related differences in hindlimb movements and activation of the soleus and tibialis anterior muscles were studied during treadmill locomotion in intact rats and in rats 4 and 10 weeks following transection and surgical repair of the sciatic nerve. In intact rats, the tibialis anterior and soleus muscles were activated reciprocally at all slopes, and the overall intensity of activity in tibialis anterior and the mid-step activity in soleus increased with increasing slope. Based on the results of principal components analysis, the pattern of activation of soleus, but not of tibialis anterior, changed significantly with slope. Slope-related differences in hindlimb kinematics were found in intact rats, and these correlated well with the demands of walking up or down slopes. Following recovery from sciatic nerve injury, the soleus and tibialis anterior were co-activated throughout much of the step cycle and there was no difference in intensity or pattern of activation with slope for either muscle. Unlike intact rats, these animals walked with their feet flat on the treadmill belt through most of the stance phase. Even so, during downslope walking limb length and limb orientation throughout the step cycle were not significantly changed from values found in intact rats. This conservation of hindlimb kinematics was not observed during level or upslope walking. These findings are interpreted as evidence that the recovering animals adopt a novel locomotor strategy that involves stiffening of the ankle joint by antagonist co-activation and compensation at more proximal joints. Their movements are most suitable to the requirements of downslope walking but the recovering rats lack the ability to adapt to the demands of level or upslope walking.
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Affiliation(s)
- Manning J Sabatier
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA.
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99
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Higham TE, Biewener AA. Functional and architectural complexity within and between muscles: regional variation and intermuscular force transmission. Philos Trans R Soc Lond B Biol Sci 2011; 366:1477-87. [PMID: 21502119 PMCID: PMC3130453 DOI: 10.1098/rstb.2010.0359] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Over the past 30 years, studies of single muscles have revealed complex patterns of regional variation in muscle architecture, activation, strain and force. In addition, muscles are often functionally integrated with other muscles in parallel or in series. Understanding the extent of this complexity and the interactions between muscles will profoundly influence how we think of muscles in relation to organismal function, and will allow us to address questions regarding the functional benefits (or lack thereof) and dynamics of this complexity under in vivo conditions. This paper has two main objectives. First, we present a cohesive and integrative review of regional variation in function within muscles, and discuss the functional ramifications that can stem from this variation. This involves splitting regional variation into passive and active components. Second, we assess the functional integration of muscles between different limb segments by presenting new data involving in vivo measurements of activation and strain from the medial gastrocnemius, iliotibialis cranialis and iliotibialis lateralis pars preacetabularis of the helmeted guinea fowl (Numida meleagris) during level running on a motorized treadmill. Future research directions for both of these objectives are presented.
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Affiliation(s)
- Timothy E Higham
- Department of Biological Sciences, Clemson University, 132 Long Hall, Clemson, SC 29634, USA.
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100
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Blum Y, Birn-Jeffery A, Daley MA, Seyfarth A. Does a crouched leg posture enhance running stability and robustness? J Theor Biol 2011; 281:97-106. [PMID: 21569779 DOI: 10.1016/j.jtbi.2011.04.029] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Revised: 04/23/2011] [Accepted: 04/27/2011] [Indexed: 12/01/2022]
Abstract
Humans and birds both walk and run bipedally on compliant legs. However, differences in leg architecture may result in species-specific leg control strategies as indicated by the observed gait patterns. In this work, control strategies for stable running are derived based on a conceptual model and compared with experimental data on running humans and pheasants (Phasianus colchicus). From a model perspective, running with compliant legs can be represented by the planar spring mass model and stabilized by applying swing leg control. Here, linear adaptations of the three leg parameters, leg angle, leg length and leg stiffness during late swing phase are assumed. Experimentally observed kinematic control parameters (leg rotation and leg length change) of human and avian running are compared, and interpreted within the context of this model, with specific focus on stability and robustness characteristics. The results suggest differences in stability characteristics and applied control strategies of human and avian running, which may relate to differences in leg posture (straight leg posture in humans, and crouched leg posture in birds). It has been suggested that crouched leg postures may improve stability. However, as the system of control strategies is overdetermined, our model findings suggest that a crouched leg posture does not necessarily enhance running stability. The model also predicts different leg stiffness adaptation rates for human and avian running, and suggests that a crouched avian leg posture, which is capable of both leg shortening and lengthening, allows for stable running without adjusting leg stiffness. In contrast, in straight-legged human running, the preparation of the ground contact seems to be more critical, requiring leg stiffness adjustment to remain stable. Finally, analysis of a simple robustness measure, the normalized maximum drop, suggests that the crouched leg posture may provide greater robustness to changes in terrain height.
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Affiliation(s)
- Yvonne Blum
- Lauflabor Locomotion Laboratory, University of Jena, Jena, Germany.
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