Fish larvae tackle the complex fluid-structure interactions of undulatory swimming with simple actuation

AbstractMost fish swim with body undulations that result from fluid-structure interactions between the fish’s internal tissues and the surrounding water. As just-hatched larvae can swim effectively without a fully-developed brain, we hypothesise that fish larvae tackle the underlying complex physics with simple actuation patterns. To address this hypothesis, we developed a dedicated experimental-numerical approach to calculate the lateral bending moment distributions, which represent the system’s net actuation. The bending moment varies over time and along the fish’s central axis due to muscle actions, passive tissues, inertia, and fluid dynamics. Our 3D analysis of a large dataset of swimming events of larvae from 3 to 12 days after fertilisation shows that these bending moment patterns are not only relatively simple but also strikingly similar throughout early development, and from fast starts to periodic swimming. This suggests also similar muscle activation patterns, allowing fish larvae to produce swimming movements relatively simply, yet effectively, while restructuring their neuromuscular control system.

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Modularity speeds up motor learning by overcoming mechanical bias in musculoskeletal geometry

Journal of The Royal Society Interface ◽

10.1098/rsif.2018.0249 ◽

2018 ◽

Vol 15 (147) ◽

pp. 20180249 ◽

Cited By ~ 1

Author(s):

Shota Hagio ◽

Motoki Kouzaki

Keyword(s):

Cortical Neurons ◽

Muscle Activation ◽

Primary Motor Cortex ◽

Neuromuscular Control ◽

Muscle Synergies ◽

Model Learning ◽

Joint Torques ◽

Muscle Activation Patterns ◽

Wide Range ◽

Simple Neural Network

We can easily learn and perform a variety of movements that fundamentally require complex neuromuscular control. Many empirical findings have demonstrated that a wide range of complex muscle activation patterns could be well captured by the combination of a few functional modules, the so-called muscle synergies. Modularity represented by muscle synergies would simplify the control of a redundant neuromuscular system. However, how the reduction of neuromuscular redundancy through a modular controller contributes to sensorimotor learning remains unclear. To clarify such roles, we constructed a simple neural network model of the motor control system that included three intermediate layers representing neurons in the primary motor cortex, spinal interneurons organized into modules and motoneurons controlling upper-arm muscles. After a model learning period to generate the desired shoulder and/or elbow joint torques, we compared the adaptation to a novel rotational perturbation between modular and non-modular models. A series of simulations demonstrated that the modules reduced the effect of the bias in the distribution of muscle pulling directions, as well as in the distribution of torques associated with individual cortical neurons, which led to a more rapid adaptation to multi-directional force generation. These results suggest that modularity is crucial not only for reducing musculoskeletal redundancy but also for overcoming mechanical bias due to the musculoskeletal geometry allowing for faster adaptation to certain external environments.

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Rotator-Cuff Muscle-Recruitment Strategies During Shoulder Rehabilitation Exercises

Journal of Sport Rehabilitation ◽

10.1123/jsr.20.4.471 ◽

2011 ◽

Vol 20 (4) ◽

pp. 471-486 ◽

Cited By ~ 4

Author(s):

Kathleen A. Swanik ◽

Kellie Huxel Bliven ◽

Charles Buz Swanik

Keyword(s):

Rotator Cuff ◽

Muscle Activation ◽

Glenohumeral Joint ◽

Neuromuscular Control ◽

Muscle Recruitment ◽

Individual Muscle ◽

Muscle Activation Patterns ◽

Outcomes Measures ◽

Rehabilitation Exercises ◽

Teres Minor

Context:There are contradictory data on optimal muscle-activation strategies for restoring shoulder stability. Further investigation of neuromuscular-control strategies for glenohumeral-joint stability will guide clinicians in decisions regarding appropriate rehabilitation exercises.Objectives:To determine whether subscapularis, infraspinatus, and teres minor (anteroposterior force couple) muscle activation differ between 4 shoulder exercises and describe coactivation ratios and individual muscle-recruitment characteristics of rotator-cuff muscles throughout each shoulder exercise.Design:Crossover.Setting:Laboratory.Participants:healthy, physically active men, age 20.55 ± 2.0 y.Interventions:4 rehabilitation exercises: pitchback, PNF D2 pattern with tubing, push-up plus, and slide board.Main Outcomes Measures:Mean coactivation level, coactivation-ratio patterns, and level (area) of muscle-activation patterns of the subscapularis, infraspinatus, and teres minor throughout each exercise.Results:Coactivation levels varied throughout each exercise. Subscapularis activity was consistently higher than that of the infraspinatus and teres minor combined at the start of each exercise and in end ranges of motion. Individual muscle-recruitment levels in the subscapularis were also different between exercises.Conclusion:Results provide descriptive data for determining normative coactivation-ratio values for muscle recruitment for the functional exercises studied. Differences in subscapularis activation suggest a reliance to resist anteriorly directed forces.

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An EMG-Driven Forward Dynamics Model to Simulate Stance Phase of Gait

ASME 2009 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2009-206715 ◽

2009 ◽

Author(s):

Qi Shao ◽

Kurt Manal ◽

Thomas S. Buchanan

Keyword(s):

Muscle Activation ◽

Stance Phase ◽

Control Strategies ◽

Neuromuscular Control ◽

Human Movement ◽

Joint Torque ◽

Forward Dynamics ◽

Activation Patterns ◽

Joint Torques ◽

Muscle Activation Patterns

Simulations based on forward dynamics have been used to identify the biomechanical mechanisms how human movement is generated. They used either net joint torques [1] or muscle forces [2, 3, 4] as actuators to drive forward simulation. However, very few models used EMG-based patterns to define muscle excitations [4] or were actually driven by EMGs. Muscle activation patterns vary from subject to subject and from movement to movement, and the activations depend on the control task, sometimes quite different even for the same joint angle and joint torque [5]. Using EMG as input can account for subjects’ different muscle activation patterns and help revealing the neuromuscular control strategies.

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Influence of Age on Neuromuscular Control during a Dynamic Weight-Bearing Task

Journal of Aging and Physical Activity ◽

10.1123/japa.17.3.327 ◽

2009 ◽

Vol 17 (3) ◽

pp. 327-343 ◽

Cited By ~ 13

Author(s):

Sangeetha Madhavan ◽

Sarah Burkart ◽

Gail Baggett ◽

Katie Nelson ◽

Trina Teckenburg ◽

...

Keyword(s):

Muscle Activation ◽

Control Strategies ◽

Weight Bearing ◽

Neuromuscular Control ◽

The Elderly ◽

Joint Injury ◽

Activation Patterns ◽

Muscle Activation Patterns ◽

Knee Movement ◽

Long Latency

Neuromuscular control strategies might change with age and predispose the elderly to knee-joint injury. The purposes of this study were to determine whether long latency responses (LLRs), muscle-activation patterns, and movement accuracy differ between the young and elderly during a novel single-limb-squat (SLS) task. Ten young and 10 elderly participants performed a series of resistive SLSs (~0–30°) while matching a computer-generated sinusoidal target. The SLS device provided a 16% body-weight resistance to knee movement. Both young and elderly showed significant overshoot error when the knee was perturbed (p< .05). Accuracy of the tracking task was similar between the young and elderly (p= .34), but the elderly required more muscle activity than the younger participants (p< .05). The elderly group had larger LLRs than the younger group (p< .05). These results support the hypothesis that neuromuscular control of the knee changes with age and might contribute to injury.

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Age-related neuromuscular function during drop jumps

Journal of Applied Physiology ◽

10.1152/japplphysiol.00430.2007 ◽

2007 ◽

Vol 103 (4) ◽

pp. 1276-1283 ◽

Cited By ~ 43

Author(s):

M. Hoffrén ◽

M. Ishikawa ◽

P. V. Komi

Keyword(s):

Muscle Activation ◽

Reaction Force ◽

Neuromuscular Control ◽

The Elderly ◽

Elderly Subjects ◽

Activation Patterns ◽

Muscle Activation Patterns ◽

Age Related ◽

Young Subjects ◽

Braking Phase

Muscle- and movement-specific fascicle-tendon interaction affects the performance of the neuromuscular system. This interaction is unknown among elderly and consequently contributes to the lack of understanding the age-related problems on neuromuscular control. The present experiment studied the age specificity of fascicle-tendon interaction of the gastrocnemius medialis (GM) muscle in drop jump (DJ) exercises. Twelve young and thirteen elderly subjects performed maximal squat jumps and DJs with maximal rebound effort on a sledge apparatus. Ankle and knee joint angles, reaction force, and electromyography (EMG) from the soleus (Sol), GM, and tibialis anterior (TA) muscles were measured together with the GM fascicle length by ultrasonography. The results showed that the measured ankle joint stiffness (AJS) during the braking phase correlated positively with the rebound speed in both age groups and that both parameters were significantly lower in the elderly than in young subjects. In both groups, the AJS correlated positively with averaged EMG (aEMG) in Sol during the braking phase and was further associated with GM activation ( r = 0.55, P < 0.01) and TA coactivation (TA/GM r = −0.4 P < 0.05) in the elderly subjects. In addition, compared with the young subjects, the elderly subjects showed significantly lower GM aEMG in the braking phase and higher aEMG in the push-off phase, indicating less utilization of tendinous tissue (TT) elasticity. These different activation patterns are in line with the mechanical behavior of GM showing significantly less fascicle shortening and relative TT stretching in the braking phase in the elderly than in the young subjects. These results suggest that age-specific muscle activation patterns as well as mechanical behaviors exist during DJs.

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A simplified fluid structure interaction model for the assessment of ship hard grounding

Journal of Marine Science and Technology ◽

10.1007/s00773-021-00862-6 ◽

2021 ◽

Author(s):

Sang Jin Kim ◽

Jung Min Sohn ◽

Pentti Kujala ◽

Spyros Hirdaris

Keyword(s):

Structural Damage ◽

Rapid Assessment ◽

Interaction Model ◽

Fluid Structure Interactions ◽

Hydrodynamic Properties ◽

Surrounding Water ◽

Fluid Structure ◽

Source Codes ◽

Added Masses ◽

Restoring Forces

AbstractThe structural damage of ships in navigational accidents is influenced by the hydrodynamic properties of surrounding water. Fluid structure interactions (FSI) in way of grounding contact can be idealized by combining commercial FEA tools and specialized hydrodynamic solvers. Despite the efficacy of these simulations, the source codes idealizing FSI are not openly available, computationally expensive and subject to limitations in terms of physical assumptions. This paper presents a unified FSI model for the assessment of ship crashworthiness following ship hard grounding. The method uses spring elements for the idealization of hydrostatic restoring forces in 3 DoF (heave, pitch, roll) and distributes the added masses in 6 DoF on the nodal points in way of contact. Comparison of results against the method of Kim et al. (2021) for the case of a barge and a Ro–Ro passenger ship demonstrate excellent idealization of ship dynamics. It is concluded that the method could be useful for rapid assessment of ship grounding scenarios and associated regulatory developments.

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