scholarly journals Examination of Weight Transfer Strategies During the Execution of Grand Battement Devant at the Barre, in the Center, and Traveling

2012 ◽  
Vol 27 (2) ◽  
pp. 74-84 ◽  
Author(s):  
Donna Krasnow ◽  
M Virginia Wilmerding ◽  
Shane Stecyk ◽  
Matthew Wyon ◽  
Yiannis Koutedakis
Keyword(s):  
Center Of Mass ◽  
Center Of Gravity ◽  
Main Effect ◽  
Transfer Strategies ◽  
Center Conditions ◽  
Primary Focus ◽  
Dance Educators ◽  
Weight Transfer ◽  
Motor Strategies ◽  
Effect Condition

The purpose of this study was to examine grand battement devant at the barre, in the center, and traveling through space. The primary focus was to consider weight transfer in three conditions: from two feet to one foot for the barre and center conditions, and from one foot to the other foot in traveling. Forty female dancers volunteered (mean age 30.0 ± 13.0 yrs) and were placed in three groups: beginner (n = 12), intermediate (n = 14), and advanced (n = 14). Data were collected with a 7-camera Vicon motion capture system using a Plug-in Gait Full Body Marker set and with two Kistler force plates. Dancers executed five grand battement devant in each of three conditions in randomized order: at the barre in 1st position, in the center in 1st position, and traveling through space. Four variables were investigated: center of gravity of the full trunk, center of gravity of the pelvis, center of gravity of the upper trunk, and center of mass. Data were analyzed in three intervals—stance to battement initiation (STN to GBI), initiation to battement peak (GBI to GBP), and peak to end (GBP to END)—and in the x-axis and y-axis. The main effect condition was significant for all four variables in both x-axis and y-axis (p<0.001). There were no significant differences for training and no significant condition 3 training interactions. Condition was significant for all three intervals (STN to GBI, GBI to GBP, and GBP to END) for all four variables in both axes (p<0.01). Dance educators might consider the importance of allocating sufficient time in dance practice to each of the three conditions—barre, center, and traveling—to ensure development of a variety of motor strategies for weight transfer.

Center of Gravity and Center of Mass

1938 ◽  
Vol 6 (2) ◽  
pp. 106-106 ◽  
Author(s):  
Michael Ference ◽  
Alvin M. Weinberg
Keyword(s):  
Center Of Mass ◽  
Center Of Gravity

Center of Gravity, Center of Mass,Centroids

2016 ◽  
pp. 29-44
Author(s):  
Dietmar Gross ◽  
Wolfgang Ehlers ◽  
Peter Wriggers ◽  
Jörg Schröder ◽  
Ralf Müller
Keyword(s):  
Center Of Mass ◽  
Center Of Gravity ◽  
Gravity Center

Achieving the Split Position in a Saut de Chat Leap

2020 ◽  
Vol 35 (2) ◽  
pp. 68-72
Author(s):  
Danielle N Jarvis ◽  
Kornelia Kulig
Keyword(s):  
Repeated Measures ◽  
Center Of Mass ◽  
Peak Height ◽  
Knee Joints ◽  
Similar Time ◽  
Dance Training ◽  
Main Effect ◽  
Hip Flexion ◽  
Post Hoc ◽  
Coordination Patterns

OBJECTIVES: Dancers frequently perform complex jumping skills that involve achieving specific body positions while in the air. An examination of how skilled dancers achieve these aesthetic demands can provide information useful for dance training. The purpose of this study was to examine the temporal coordination of the hip and knee joints during the flight phase of a saut de chat leap, where dancers aim to achieve a split position in the air when the center of mass (COM) reaches peak height. METHODS: Thirty healthy, experienced dancers with 22.5±4.5 years of dance training performed 5 saut de chat leaps. The timing of peak hip and knee joint angles and velocities for the takeoff and leading legs were extracted and compared to the time when COM reached peak height in the leap using a repeated measures ANOVA, with post-hoc comparisons made using paired t-tests. RESULTS: Dancers demonstrated significant differences in timing associated with achieving the split position (main effect p<0.001), with only peak leading leg hip flexion occurring at a similar time to the COM reaching peak height (paired t-test p=0.074). CONCLUSIONS: The results of this study provide insight into coordination patterns used by trained dancers. Trained dancers demonstrate patterns in timing that may be important for successful performance. The hip and knee coordination patterns during flight demonstrate how dancers work to achieve the desired aesthetics of a saut de chat leap. However, it appears that dancers do not reach the full split position at the height of the leap, as would be aesthetically desirable.

Some “laws” of gastropod shell form

Paleobiology ◽  
1977 ◽  
Vol 3 (2) ◽  
pp. 196-206 ◽  
Author(s):  
Robert M. Linsley
Keyword(s):  
Center Of Mass ◽  
Mantle Cavity ◽  
Center Of Gravity ◽  
The Body ◽  
Water Current ◽  
Gastropod Shell ◽  
Shell Form ◽  
Body Whorl ◽  
Anterior Posterior ◽  
Anterior Posterior Axis

Five generalizations derived from the shell form of prosobranch gastropods are developed. (1) A univalve of more than one volution whose aperture lies in a plane that passes through the axis of coiling does not live with the aperture parallel to the substrate. (2) A univalve of more than one volution whose aperture lies in a plane that is tangential to the body whorl does live with the plane of the aperture parallel to the substrate. (3) Gastropods with tangential apertures, when extended, support the shell so that the center of mass of the shell and its contents is over the midline of the cephalopedal mass; this balancing of the shell may be accomplished either by regulatory detorsion, by inclination or by a combination thereof, to keep the center of gravity of the shell as low as possible. (4) Angulations or re-entrants in the gastropod aperture are usually indicative of inhalent or exhalent areas; inhalent areas are directed as far anteriorly as possible. (5) Gastropods having elongated apertures possess only a single gill and develop a water current through the mantle cavity from anterior to posterior along the long axis of the aperture; this axis is subparallel to the anterior-posterior axis of the foot.These generalizations are then used as the basis for some deductive interpretations of behavioral modes of Paleozoic Gastropoda.

Estimation and Hypothesis Testing for the Loglinear Model

1989 ◽  
Vol 33 (3) ◽  
pp. 220-241 ◽  
Author(s):  
Patricia L. Busk ◽  
Leonard A. Marascuilo
Keyword(s):  
Hypothesis Testing ◽  
Confidence Intervals ◽  
Model Building ◽  
Loglinear Model ◽  
Frequency Data ◽  
Interval Estimates ◽  
Main Effect ◽  
Dependent Variables ◽  
Primary Focus ◽  
Post Hoc

In recent years, the loglinear model has been proposed and used for analysing frequency data in multidimensional contingency tables. The primary focus of the literature has been on model building and only secondarily on hypothesis testing and estimation. This paper extends Kennedy's (1988) description by presenting post hoc procedures for statistically evaluating treatment effects, contrasts, and confidence intervals. It illustrates methods for main effect and interaction contrasts and pays special attention to odds ratios and their interval estimates. Procedures are described for treating the variables as interdependent and for the case where there are independent and dependent variables—both ordered and unordered.

scholarly journals Biomechanical Control of Paretic Lower Limb During Imposed Weight Transfer in Individuals Post-Stroke

2020 ◽  
Author(s):  
Hao-Yuan Hsiao ◽  
Vicki L Gray ◽  
James Borrelli ◽  
Mark W Rogers
Keyword(s):  
Lower Limb ◽  
Center Of Pressure ◽  
Weight Bearing ◽  
Center Of Mass ◽  
Step Test ◽  
Control Group ◽  
Post Stroke ◽  
Paretic Limb ◽  
Four Square ◽  
Weight Transfer

Abstract Background: stroke is a leading cause of disability with associated hemiparesis resulting in difficulty bearing and transferring weight on to the paretic limb. Difficulties in weight bearing and weight transfer may result in impaired mobility and balance, increased fall risk, and decreased community engagement. Despite considerable efforts aimed at improving weight transfer after stroke, impairments in its neuromotor and biomechanical control remain poorly understood. In the present study, a novel experimental paradigm was used to characterize differences in weight transfer biomechanics in individuals with chronic stroke versus able-bodied controls. Methods: fifteen participants with stroke and fifteen age-matched able-bodied controls participated in the study. Participants stood with one foot on each of two custom built platforms. One of the platforms dropped 4.3 cm vertically to induce lateral weight transfer and weight bearing. Paretic lower extremity joint kinematics, vertical ground reaction forces, and center of pressure velocity were measured. All participants completed the clinical Step Test and Four-Square Step Test. Results: reduced paretic ankle, knee, and hip joint angular displacement and velocity, delayed ankle and knee inter-joint timing, and altered center of pressure (COP) and center of mass control were exhibited in the stroke group compared to the control group. In addition, paretic COP velocity stabilization time during induced weight transfer predicted Four-Square Step Test scores in individuals post-stroke. Conclusions: the induced weight transfer approach identified stroke-related abnormalities in the control of weight transfer towards the paretic limb side compared to controls. Decreased joint flexion of the paretic ankle and knee, altered inter-joint timing, and altered COP and center of mass control appear to limit rapid lower limb loading ability. Future work will investigate the potential of improving functional weight transfer through induced weight transfer training exercise.

Is the regulation of the center of mass maintained during leg movement under microgravity conditions?

1996 ◽  
Vol 76 (2) ◽  
pp. 1212-1223 ◽  
Author(s):  
L. Mouchnino ◽  
M. Cincera ◽  
J. C. Fabre ◽  
C. Assaiante ◽  
B. Amblard ◽  
...  
Keyword(s):  
Body Weight ◽  
Parabolic Flight ◽  
Center Of Mass ◽  
Microgravity Condition ◽  
The Body ◽  
Gravitoinertial Force ◽  
Microgravity Conditions ◽  
Leg Movement ◽  
Single Limb Support ◽  
Weight Transfer

1. Investigations on stance regulation have already suggested that the body's center of mass is the variable controlled by the CNS to maintain equilibrium. The aim of this study was to determine how the center of mass of the body is regulated when leg movements are made under different gravitoinertial force conditions. 2. Kinematic and electromyographic (EMG) recordings were made during both straight-and-level flight (earth-normal gravity condition, nG) and periods of weightlessness in parabolic flight (microgravity condition, microG). The standing subjects were restrained to the floor (kept from floating away in microG) and were instructed to raise one leg laterally to an angle of 45 degrees as fast as possible. 3. Two modes of center of mass (CM) control were identified during leg movement in nG: a "shift mode" and a "stabilization mode." The shift mode served to transfer the CM toward the supporting side before the leg raising, and it preceded the phase of single limb support. The stabilization mode took place after the CM shift was completed and was aimed at stabilizing the CM during raising of the leg. In this phase, the movement of the raising leg is counterbalanced by a lateral inclination of the trunk in the opposite direction. As a consequence, CM position did not change with respect to the position reached before the leg raising, and its projection on the ground remained within the support area delineated by the stance foot. 4. Under microG, the CM position did not change before the leg raising. Moreover, gastrocnemius medialis activity observed in the moving leg under nG, preceding the initiation of the body weight transfer toward the supporting leg, was greatly reduced. While the leg is raising, the simultaneous and opposite lateral trunk movement was still present in microG. 5. Results suggest that the body weight transfer corresponding to the shift mode, might depend on the gravity constraints, whereas the stabilization mode, which remains unchanged in microG, might be a motor stereotype that does not depend on the gravity conditions.

scholarly journals Coordinated Ground Forces Exerted by Buttocks and Feet are Adequately Programmed for Weight Transfer During Sit-to-Stand

1999 ◽  
Vol 82 (6) ◽  
pp. 3021-3029 ◽  
Author(s):  
Helga Hirschfeld ◽  
Maria Thorsteinsdottir ◽  
Elisabeth Olsson
Keyword(s):  
Center Of Mass ◽  
Three Dimensional ◽  
The Body ◽  
Whole Body ◽  
Sit To Stand ◽  
Preparatory Phase ◽  
Base Distance ◽  
Left And Right ◽  
Hip Flexion ◽  
Weight Transfer

The purpose of this study was to test the hypothesis whether weight transfer during sit-to-stand (STS) is the result of coordinated ground forces exerted by buttocks and feet before seat-off. Whole-body kinematics and three-dimensional ground forces from left and right buttock as well as from left and right foot were recorded for seven adults during STS. We defined a preparatory phase from onset of the first detectable anterior/posterior (A/P) force to seat-off (buttock forces fell to 0) and a rising phase from seat-off to the decrease of center of mass (CoM) vertical velocity to zero. STS was induced by an increase of vertical and backward directed ground forces exerted by the buttocks that significantly preceded the onset of any trunk movement. All ground forces peaked before or around the moment of seat-off, whereas all kinematic variables, except trunk forward rotation and hip flexion, peaked after seat-off, during or after the rising phase. The present study suggests that the weight transfer from sit to stand is induced by ground forces exerted by buttocks and feet before seat-off, i.e., during the preparatory phase. The buttocks generate the isometric “rising forces,” e.g., the propulsive impulse for the forward acceleration of the body, while the feet apply adequate damping control before seat-off. This indicates that the rising movement is a result of these coordinated forces, targeted to match the subject's weight and support base distance between buttocks and feet. The single peaked, bell-shaped profiles peaking before seat-off, were seen beneath buttocks for the “rising drive,” i.e., between the time of peak backward directed force and seat-off, as well as beneath the feet for the “damping drive,” i.e., from onset to the peak of forward-directed force and for CoM A/P velocity. This suggests that both beginning and end of the weight transfer process are programmed before seat-off. The peak deceleration of A/P CoM took place shortly (∼100 ms) after CoM peak velocity, resulting in a well controlled CoM deceleration before seat-off. In contrast to the view of other authors, this suggests that body equilibrium is controlled during weight transfer.

Kinematic Differences Exist Between the Fastball, Changeup, Curveball, and Dropball Pitch Types in Collegiate Softball Pitchers

2021 ◽  
Vol 49 (4) ◽  
pp. 1065-1072
Author(s):  
Jessica L. Downs ◽  
Nicole M. Bordelon ◽  
Kenzie B. Friesen ◽  
David M. Shannon ◽  
Gretchen D. Oliver
Keyword(s):  
Stride Length ◽  
Center Of Mass ◽  
Elbow Flexion ◽  
Trunk Rotation ◽  
Lateral Flexion ◽  
Trunk Flexion ◽  
Significant Difference ◽  
Main Effect ◽  
And Performance ◽  
Trunk Extension

Background: A majority of softball literature focuses on the mechanics associated with pain and injury within a single pitch type per study; however, the generalizability of these findings is unknown since a kinematic comparison has yet to be performed between pitch types. Understanding kinematic differences between pitch types can be used to identify risk factors for injury, improve safety guidelines, and improve performance by linking specific mechanics with desired pitch outcomes. Hypothesis/Purpose: The purpose of this study was to compare kinematics between the fastball, changeup, curveball, and dropball pitch types in collegiate softball pitchers. It was hypothesized that there would be significant kinematic differences between pitch types. Study Design: Descriptive laboratory study. Methods: A total of 28 female collegiate softball pitchers pitched 3 trials of each pitch type to a catcher at regulation distance. Pitch speed, stride length, trunk extension, trunk rotation, trunk lateral flexion, elbow flexion, and center of mass for each trial were calculated using an electromagnetic motion capture system and were averaged for analysis. A 1-way analysis of variance (ANOVA) was used to investigate pitch speed differences between the 4 pitch types. A 4 (pitch type) × 5 (event) within-athlete multivariate ANOVA was also used to determine kinematic differences. Results: The results revealed a significant difference in pitch speed between pitch types; a pitch type main effect for trunk extension, trunk rotation, trunk lateral flexion, and center of mass; and an event main effect for all variables except stride length. The results also revealed a pitch type by event interaction for trunk flexion, trunk lateral flexion, and center of mass. Specifically, the dropball type had less trunk extension than the fastball at all pitching events. Similarly, the curveball type had a more posteriorly shifted center of mass than the dropball at the last 3 pitching events of foot contact, ball release and follow-through. Conclusion: Significant kinematic differences exist between pitch types, but these differences may be necessary to execute desired pitch outcomes. Clinical Relevance: This is the first study to analyze kinematic differences between pitch types in softball pitchers. Understanding the effects of different pitch types on kinematic parameters may enhance injury prevention and performance strategies for softball pitchers.

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