scholarly journals An exploration of strategies used by dressage horses to control moments around the center of mass when performing passage

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3866 ◽  
Author(s):  
Hilary M. Clayton ◽  
Sarah Jane Hobbs
Keyword(s):  
Sagittal Plane ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Force Production ◽  
The Body ◽  
Camera Motion ◽  
Slow Speed ◽  
Moment Arms ◽  
Trunk Posture ◽  
The Moment

BackgroundLocomotion results from the generation of ground reaction forces (GRF) that cause translations of the center of mass (COM) and generate moments that rotate the body around the COM. The trot is a diagonally-synchronized gait performed by horses at intermediate locomotor speeds. Passage is a variant of the trot performed by highly-trained dressage horses. It is distinguished from trot by having a slow speed of progression combined with great animation of the limbs in the swing phase. The slow speed of passage challenges the horse’s ability to control the sagittal-plane moments around the COM. Footfall patterns and peak GRF are known to differ between passage and trot, but their effects on balance management, which we define here as the ability to control nose-up/nose-down pitching moments around the horse’s COM to maintain a state of equilibrium, are not known. The objective was to investigate which biomechanical variables influence pitching moments around the COM in passage.MethodsThree highly-trained dressage horses were captured by a 10-camera motion analysis system (120 Hz) as they were ridden in passage over four force platforms (960 Hz). A full-body marker set was used to track the horse’s COM and measure balance variables including total body center of pressure (COP), pitching moments, diagonal dissociation timing, peak force production, limb protraction–retraction, and trunk posture. A total of twenty passage steps were extracted and partial correlation (accounting for horse) was used to investigate significant (P < 0.05) relationships between variables.ResultsHindlimb mean protraction–retraction correlated significantly with peak hindlimb propulsive forces (R = 0.821;P < 0.01), mean pitching moments (R = 0.546,P = 0.016), trunk range of motion, COM craniocaudal location and diagonal dissociation time (P < 0.05).DiscussionPitching moments around the COM were controlled by a combination of kinematic and kinetic adjustments that involve coordinated changes in GRF magnitudes, GRF distribution between the diagonal limb pairs, and the moment arms of the vertical GRFs. The moment arms depend on hoof placements relative to the COM, which were adjusted by changing limb protraction–retraction angles. Nose-up pitching moments could also be increased by providing a larger hindlimb propulsive GRF.

scholarly journals Can Muscle Stiffness Alone Stabilize Upright Standing?

1999 ◽  
Vol 82 (3) ◽  
pp. 1622-1626 ◽  
Author(s):  
Pietro G. Morasso ◽  
Marco Schieppati
Keyword(s):  
Center Of Pressure ◽  
Center Of Mass ◽  
Muscle Stiffness ◽  
The Body ◽  
Ankle Muscles ◽  
Upright Standing ◽  
Stiffness Control ◽  
Control Patterns ◽  
Physiological Values

A stiffness control model for the stabilization of sway has been proposed recently. This paper discusses two inadequacies of the model: modeling and empiric consistency. First, we show that the in-phase relation between the trajectories of the center of pressure and the center of mass is determined by physics, not by control patterns. Second, we show that physiological values of stiffness of the ankle muscles are insufficient to stabilize the body “inverted pendulum.” The evidence of active mechanisms of sway stabilization is reviewed, pointing out the potentially crucial role of foot skin and muscle receptors.

Many-legged maneuverability: dynamics of turning in hexapods

1999 ◽  
Vol 202 (12) ◽  
pp. 1603-1623 ◽  
Author(s):  
D.L. Jindrich ◽  
R.J. Full
Keyword(s):  
Horizontal Plane ◽  
Center Of Mass ◽  
Vertical Plane ◽  
Force Production ◽  
The Body ◽  
Mean Velocity ◽  
Blaberus Discoidalis ◽  
Body Design ◽  
Reaction Forces ◽  
Straight Ahead

Remarkable similarities in the vertical plane of forward motion exist among diverse legged runners. The effect of differences in posture may be reflected instead in maneuverability occurring in the horizontal plane. The maneuver we selected was turning during rapid running by the cockroach Blaberus discoidalis, a sprawled-postured arthropod. Executing a turn successfully involves at least two requirements. The animal's mean heading (the direction of the mean velocity vector of the center of mass) must be deflected, and the animal's body must rotate to keep the body axis aligned with the heading. We used two-dimensional kinematics to estimate net forces and rotational torques, and a photoelastic technique to estimate single-leg ground-reaction forces during turning. Stride frequencies and duty factors did not differ among legs during turning. The inside legs ended their steps closer to the body than during straight-ahead running, suggesting that they contributed to turning the body. However, the inside legs did not contribute forces or torques to turning the body, but actively pushed against the turn. Legs farther from the center of rotation on the outside of the turn contributed the majority of force and torque impulse which caused the body to turn. The dynamics of turning could not be predicted from kinematic measurements alone. To interpret the single-leg forces observed during turning, we have developed a general model that relates leg force production and leg position to turning performance. The model predicts that all legs could turn the body. Front legs can contribute most effectively to turning by producing forces nearly perpendicular to the heading, whereas middle and hind legs must produce additional force parallel to the heading. The force production necessary to turn required only minor alterations in the force hexapods generate during dynamically stable, straight-ahead locomotion. A consideration of maneuverability in the horizontal plane revealed that a sprawled-postured, hexapodal body design may provide exceptional performance with simplified control.

scholarly journals Sensorimotor feedback based on task-relevant error robustly predicts temporal recruitment and multidirectional tuning of muscle synergies

2013 ◽  
Vol 109 (1) ◽  
pp. 31-45 ◽  
Author(s):  
Seyed A. Safavynia ◽  
Lena H. Ting
Keyword(s):  
Sagittal Plane ◽  
Balance Control ◽  
Center Of Mass ◽  
The Body ◽  
Muscle Synergy ◽  
Muscle Synergies ◽  
Muscle Coordination ◽  
Initial State ◽  
Sensorimotor Feedback ◽  
Task Level

We hypothesized that motor outputs are hierarchically organized such that descending temporal commands based on desired task-level goals flexibly recruit muscle synergies that specify the spatial patterns of muscle coordination that allow the task to be achieved. According to this hypothesis, it should be possible to predict the patterns of muscle synergy recruitment based on task-level goals. We demonstrated that the temporal recruitment of muscle synergies during standing balance control was robustly predicted across multiple perturbation directions based on delayed sensorimotor feedback of center of mass (CoM) kinematics (displacement, velocity, and acceleration). The modulation of a muscle synergy's recruitment amplitude across perturbation directions was predicted by the projection of CoM kinematic variables along the preferred tuning direction(s), generating cosine tuning functions. Moreover, these findings were robust in biphasic perturbations that initially imposed a perturbation in the sagittal plane and then, before sagittal balance was recovered, perturbed the body in multiple directions. Therefore, biphasic perturbations caused the initial state of the CoM to differ from the desired state, and muscle synergy recruitment was predicted based on the error between the actual and desired upright state of the CoM. These results demonstrate that that temporal motor commands to muscle synergies reflect task-relevant error as opposed to sensory inflow. The proposed hierarchical framework may represent a common principle of motor control across motor tasks and levels of the nervous system, allowing motor intentions to be transformed into motor actions.

Gait style as an etiology to chronic postural pain. Part II. Postural compensatory process

1993 ◽  
Vol 83 (11) ◽  
pp. 615-624 ◽  
Author(s):  
HJ Dananberg
Keyword(s):  
Kinetic Energy ◽  
Sagittal Plane ◽  
Center Of Mass ◽  
Metatarsophalangeal Joint ◽  
Specific Pattern ◽  
The Body ◽  
First Metatarsophalangeal Joint ◽  
The Past ◽  
Compensatory Process ◽  
Methods Of Treatment

The body is designed to pull the center of mass over a single pivotal site formed by dorsiflexion of the first metatarsophalangeal joint. If this response dorsiflexion motion is blocked by functional hallux limitus, then the kinetic energy, which is created for this motion, must somehow be dissipated. The process by which this dissipation occurs creates a specific pattern of compensations which, in the past, has been seen as primary motions unrelated to sagittal plane blockade. These compensatory motions are described along with a brief section concerning the methods of treatment.

scholarly journals The Effect of Step Width on Muscle Contributions to Body Mass Center Acceleration During the First Stance of Sprinting

2021 ◽  
Vol 9 ◽  
Author(s):  
Ruoli Wang ◽  
Laura Martín de Azcárate ◽  
Paul Sandamas ◽  
Anton Arndt ◽  
Elena M. Gutierrez-Farewik
Keyword(s):  
Lower Limb ◽  
Sagittal Plane ◽  
Center Of Mass ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Gluteus Medius ◽  
Biceps Femoris ◽  
The Body ◽  
Step Width ◽  
Acceleration Analysis

BackgroundAt the beginning of a sprint, the acceleration of the body center of mass (COM) is driven mostly forward and vertically in order to move from an initial crouched position to a more forward-leaning position. Individual muscle contributions to COM accelerations have not been previously studied in a sprint with induced acceleration analysis, nor have muscle contributions to the mediolateral COM accelerations received much attention. This study aimed to analyze major lower-limb muscle contributions to the body COM in the three global planes during the first step of a sprint start. We also investigated the influence of step width on muscle contributions in both naturally wide sprint starts (natural trials) and in sprint starts in which the step width was restricted (narrow trials).MethodMotion data from four competitive sprinters (2 male and 2 female) were collected in their natural sprint style and in trials with a restricted step width. An induced acceleration analysis was performed to study the contribution from eight major lower limb muscles (soleus, gastrocnemius, rectus femoris, vasti, gluteus maximus, gluteus medius, biceps femoris, and adductors) to acceleration of the body COM.ResultsIn natural trials, soleus was the main contributor to forward (propulsion) and vertical (support) COM acceleration and the three vasti (vastus intermedius, lateralis and medialis) were the main contributors to medial COM acceleration. In the narrow trials, soleus was still the major contributor to COM propulsion, though its contribution was considerably decreased. Likewise, the three vasti were still the main contributors to support and to medial COM acceleration, though their contribution was lower than in the natural trials. Overall, most muscle contributions to COM acceleration in the sagittal plane were reduced. At the joint level, muscles contributed overall more to COM support than to propulsion in the first step of sprinting. In the narrow trials, reduced COM propulsion and particularly support were observed compared to the natural trials.ConclusionThe natural wide steps provide a preferable body configuration to propel and support the COM in the sprint starts. No advantage in muscular contributions to support or propel the COM was found in narrower step widths.

scholarly journals Musculoskeletal modeling of an ostrich (Struthio camelus) pelvic limb: Influence of limb orientation on muscular capacity during locomotion

2014 ◽  
Author(s):  
John R Hutchinson ◽  
Jeffery W Rankin ◽  
Jonas Rubenson ◽  
Kate H Rosenbluth ◽  
Robert A Siston ◽  
...  
Keyword(s):  
Muscle Function ◽  
Sagittal Plane ◽  
Dynamic Properties ◽  
Three Dimensional ◽  
Limb Muscle ◽  
Struthio Camelus ◽  
Moment Arms ◽  
Extensor Muscles ◽  
Pelvic Limb ◽  
The Moment

We developed a three-dimensional, biomechanical computer model of the 36 major pelvic limb muscle groups in an ostrich (Struthio camelus) to investigate muscle function in this, the largest of extant birds and model organism for many studies of locomotor mechanics, body size, anatomy and evolution. Combined with experimental data, we use this model to test two main hypotheses. We first query whether ostriches use limb orientations (joint angles) that optimize the moment-generating capacities of their muscles during walking or running. Next, we test whether ostriches use limb orientations at mid-stance that keep their extensor muscles near maximal, and flexor muscles near minimal, moment arms. Our two hypotheses relate to the control priorities that a large bipedal animal might evolve under biomechanical constraints to achieve more effective static weight support. We find that ostriches do not use limb orientations to optimize the moment-generating capacities or moment arms of their muscles. We infer that dynamic properties of muscles or tendons might be better candidates for locomotor optimization. Regardless, general principles explaining why species choose particular joint orientations during locomotion are lacking, raising the question of whether such general principles exist or if clades evolve different patterns (e.g. weighting of muscle force-length or force-velocity properties in selecting postures). This leaves theoretical studies of muscle moment arms estimated for extinct animals at an impasse until studies of extant taxa answer these questions. Finally, we compare our model’s results against those of two prior studies of ostrich limb muscle moment arms, finding general agreement for many muscles. Some flexor and extensor muscles exhibit self-stabilization patterns (posture-dependent switches between flexor/extensor action) that ostriches may use to coordinate their locomotion. However, some conspicuous areas of disagreement in our results illustrate some cautionary principles. Importantly, tendon-travel empirical measurements of muscle moment arms must be carefully designed to preserve 3D muscle geometry lest their accuracy suffer relative to that of anatomically realistic models. The dearth of accurate experimental measurements of 3D moment arms of muscles in birds leaves uncertainty regarding the relative accuracy of different modelling or experimental datasets such as in ostriches. Our model, however, provides a comprehensive set of 3D estimates of muscle actions in ostriches for the first time, emphasizing that avian limb mechanics are highly three-dimensional and complex, and how no muscles act purely in the sagittal plane. A comparative synthesis of experiments and models such as ours could provide powerful synthesis into how anatomy, mechanics and control interact during locomotion and how these interactions evolve. Such a framework could remove obstacles impeding the analysis of muscle function in extinct taxa.

Attributes of Quiet Stance in the Chronic Spinal Cat

1999 ◽  
Vol 82 (6) ◽  
pp. 3056-3065 ◽  
Author(s):  
Joyce Fung ◽  
Jane M. Macpherson
Keyword(s):  
Center Of Pressure ◽  
Center Of Mass ◽  
Close Relation ◽  
Daily Basis ◽  
The Body ◽  
Spinal Reflexes ◽  
Emg Activity ◽  
Axis Orientation ◽  
Dynamic Task ◽  
Horizontal Orientation

Standing is a dynamic task that requires antigravity support of the body mass and active regulation of the position of the body center of mass. This study examined the extent to which the chronic spinal cat can maintain postural orientation during stance and adapt to changes in stance distance (fore-hindpaw separation). Intact cats adapt to changes in stance distance by maintaining a constant horizontal orientation of the trunk and changing orientation of the limbs, while keeping intralimb geometry constant and aligning the ground reaction forces closely with the limb axes. Postural adaptation was compared in four cats before and after spinalization at the T6 level, in terms of the forces exerted by each paw against the support, body geometry (kinematics) and electromyographic (EMG) activity recorded from chronic, indwelling electrodes, as well as the computed net torques in the fore and hindlimbs. Five fore-hindpaw distances spanning the preferred distance were tested before spinalization, with a total range of 20 cm from the shortest to the longest stance. After spinalization, the cats were trained on a daily basis to stand on the force platform, and all four cats were able to support their full body weight. Three of the four cats could adapt to changes in stance distance, but the range was smaller and biased toward the shorter distances. The fourth cat could stand only at one stance distance, which was 8 cm shorter than the preferred distance before spinalization. All cats shifted their center of pressure closer to the forelimbs after spinalization, but the amount of shift could largely be accounted for by the weight loss in the hindquarters. The three cats that could adapt to changes in stance distance used a similar strategy as the intact cat by constraining the trunk and changing orientation of the limb axes in close relation with the forces exerted by each limb. However, different postures in the fore- and hindlimbs were adopted, particularly at the scapula (more extended) and pelvis (tipped more anteriorly). Other changes from control included a redistribution of net extensor torque across the joints of the forelimb and of the hindlimb. We concluded that the general form of body axis orientation is relatively conserved in the spinal cat, suggesting that the lumbosacral spinal circuitry includes rudimentary set points for hindlimb geometry. Both mechanical and neural elements can contribute toward maintaining body geometry through stiffness regulation and spinal reflexes.

The effect of drywall lifting method on workers' balance in a laboratory-based simulation

2003 ◽  
Vol 3 (4) ◽  
pp. 235-249
Author(s):  
Christopher S. Pan ◽  
Sharon Chiou ◽  
Scott Hendricks
Keyword(s):  
Postural Stability ◽  
Material Handling ◽  
Center Of Pressure ◽  
Body Movement ◽  
Center Of Mass ◽  
Principal Component ◽  
Work Practice ◽  
Camera Motion ◽  
Kinematic Analyses ◽  
Univariate Analyses

Voluntary body movement can import a perturbation to the postural stability/balance of a human body. Heavy manual material handling such as drywall lifting may increase this perturbation. The objective of this laboratory-based study was to quantify workers' postural stability while lifting drywall sheets through kinetic and kinematic analyses, and to identify the drywall lifting methods that caused the least perturbation on workers' balance. Sixty male construction workers participated in this study. A simulated drywall-lifting workstation was built and all subjects performed one of the four randomly assigned lifting methods. Kinetic and kinematic measurements were synchronized and collected using a piezoelectric force platform and a five-camera motion analysis system. Both center-of-pressure (COP) and center-of-mass (COM) data were analyzed to assess workers' postural stability. Univariate analyses and principal component analyses (PCA) were used to analyze 13 COP-based and 21 COM-based variables. Results from the univariate analyses and PCA significantly indicated that the three horizontal lifting methods created less perturbation than the vertical lifting method. Based on the results of this study and prior studies, it is concluded that horizontal lifting with both hands on top of the drywall appears to be the best work practice to reduce manual drywall handling hazards associated with fall potential and overexertion injuries.

scholarly journals Analysis of Postural Instability in the Upright Position on Narrow Platforms and the Interactions with Postural Constraints

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3909
Author(s):  
Atsushi Sugama ◽  
Akihiko Seo
Keyword(s):  
Postural Balance ◽  
Sagittal Plane ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Upright Position ◽  
Pendulum Model ◽  
Working Postures ◽  
Loss Of Balance ◽  
Highly Correlated ◽  
Anterior Posterior

Background: Loss of balance is a considerable risk factor for workers while using ladders, because they are required to maintain static postural balance on platforms of a restricted size. This study observed center of mass (CoM) and center of pressure (CoP) behaviors and evaluated the effects of the platform depth (anterior–posterior length) and working postures. Methods: Eleven male participants stood on four platforms with depths ranging from 6 to 15 cm and maintained their positions for 60 s while performing or not performing other tasks (object holding, upward viewing, or both simultaneously). The kinematics were analyzed on the sagittal plane based on the inverse pendulum model. Results: The absolute moving range for the CoP–CoM linearly increased with the decreasing platform depth, and the working postures affected the slopes of the linear fits. The relative range of CoP–CoM displacement on narrow platforms was highly correlated with the subjective sense of instability. Conclusions: Monitoring the CoP is effective for a better understanding and evaluation of static postural balance. This study’s findings contribute to improving the design of work equipment through the use of wider platforms that are robust against the effects of working postures.

Indirect estimates of wing-propulsion forces in horizontally diving Atlantic puffins (Fratercula arctica L.)

2003 ◽  
Vol 81 (5) ◽  
pp. 816-822 ◽  
Author(s):  
L Christoffer Johansson
Keyword(s):  
Drag Coefficient ◽  
Video Sequence ◽  
Sagittal Plane ◽  
Force Production ◽  
The Body ◽  
Fratercula Arctica ◽  
Body Drag ◽  
Reduced Frequency ◽  
Hydrodynamic Mechanism ◽  
Propulsive Mechanism

Instantaneous force production in wing-propelled diving Atlantic puffins (Fratercula arctica) was investigated using four birds for which instantaneous estimates of velocity and acceleration of the body were made. The quasi-steady resultant force acting on the body in the sagittal plane was calculated using acceleration reaction coefficients, buoyancy estimates, and drag coefficients taken from the literature and calculated, using two different methods, from a video sequence of a puffin gliding (CDw = 0.021 and 0.026, respectively). The forces calculated from the motion of the body coincide well with the wing-beat cycle, with a forward- and upward-directed force produced by the wings during the downstroke and a forward- and downward-directed force produced during the upstroke. The result suggests that a thrust force may also be produced during at least the lower-stroke reversal. This means either that there may exist some undescribed propulsive mechanism, possibly caused by an interaction of the wings beneath the body, or that the body drag coefficient may be overestimated. However, the body drag coefficient calculated in the study is close to the coefficients measured on dead birds. Furthermore, I conclude that the high reduced frequency (average 0.82) suggests a non-steady-state hydrodynamic mechanism of wing-propelled diving in puffins.

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