LONG JUMP: MECHANICAL AND ENERGETIC ASPECTS

2004 ◽  
Vol 04 (04) ◽  
pp. 535-557 ◽  
Author(s):  
T. K. KARALIS
Keyword(s):  
Contact Point ◽  
Reaction Force ◽  
Vertical Component ◽  
Centre Of Mass ◽  
Force Vector ◽  
Direct Measurements ◽  
Long Jump ◽  
The Mean ◽  
Vector Formula ◽  
Mass Position

The use of variation techniques is applied to investigate jumper's posture at take-off, resulting in maximum distance of jump. Explicit expressions have been derived between: (i) the take-off angle ϕT (formed by the line connecting the contact point of the leg driving the jump with the ground to the centre of mass position and the horizontal), (ii) the ratio [Formula: see text] of the mean vertical component of the ground reaction force vector to athlete's weight at take-off, (iii) the time spent for the mid-support/take-off phase TT, and (iv) the change in the vertical component of the displacement of the centre of mass compared with the take-off foot ΔyT, measured between two extreme postures, i.e. the mid-support and the take-off phase. The method is illustrated by calculating the state vector [Formula: see text] at take-off, in connection with the take-off angle ϕT. The results are compared to direct measurements from real long jumps.

Associations between ground reaction force waveforms and sprint start performance

2019 ◽  
Vol 14 (5) ◽  
pp. 658-666 ◽  
Author(s):  
Steffi L Colyer ◽  
Philip Graham-Smith ◽  
Aki IT Salo
Keyword(s):  
Reaction Force ◽  
Statistical Parametric Mapping ◽  
Force Production ◽  
Mass Motion ◽  
Ground Reaction Forces ◽  
Centre Of Mass ◽  
Specific Training ◽  
Force Vector ◽  
Reaction Forces ◽  
External Power

Ground reaction forces produced on the blocks determine an athlete’s centre of mass motion during the sprint start, which is crucial to sprint performance. This study aimed to understand how force waveforms are associated with better sprint start performance. Fifty-seven sprinters (from junior to world elite) performed a series of block starts during which the ground reaction forces produced by the legs and arms were separately measured. Statistical parametric mapping (linear regression) revealed specific phases of these waveforms where forces were associated with average horizontal external power. Better performances were achieved by producing higher forces and directing the force vector more horizontally during the initial parts of the block phase (17–34% and 5–37%, respectively). During the mid-push (around the time of rear block exit: ∼54% of the block push), magnitudes of front block force differentiated performers, but orientation did not. Consequently, the ability to sustain high forces during the transition from bilateral to unilateral pushing was a performance-differentiating factor. Better athletes also exhibited a higher ratio of forces on the front block in the latter parts of unilateral pushing (81–92% of the block push), which seemed to allow these athletes to exit the blocks with lower centre of mass projection angles. Training should reflect these kinetic requirements, but also include technique-based aspects to increase both force production and orientation capacities. Specific training focused on enhancing anteroposterior force production during the transition between double- to single-leg propulsion could be beneficial for overall sprint start performance.

scholarly journals Small changes in ball position at address cause a chain effect in golf swing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sung Eun Kim ◽  
Jangyun Lee ◽  
Sae Yong Lee ◽  
Hae-Dong Lee ◽  
Jae Kun Shim ◽  
...  
Keyword(s):  
Ground Reaction Force ◽  
Reaction Force ◽  
Statistical Parametric Mapping ◽  
Golf Swing ◽  
Whole Body ◽  
Centre Of Mass ◽  
Body Segment ◽  
A Chain ◽  
Professional Golfers ◽  
The Right

AbstractThe purpose of this study was to investigate how the ball position along the mediolateral (M-L) direction of a golfer causes a chain effect in the ground reaction force, body segment and joint angles, and whole-body centre of mass during the golf swing. Twenty professional golfers were asked to complete five straight shots for each 5 different ball positions along M-L: 4.27 cm (ball diameter), 2.14 cm (ball radius), 0 cm (reference position at preferred ball position), – 2.14 cm, and – 4.27 cm, while their ground reaction force and body segment motions were captured. The dependant variables were calculated at 14 swing events from address to impact, and the differences between the ball positions were evaluated using Statistical Parametric Mapping. The left-sided ball positions at address showed a greater weight distribution on the left foot with a more open shoulder angle compared to the reference ball position, whereas the trend was reversed for the right-sided ball positions. These trends disappeared during the backswing and reappeared during the downswing. The whole-body centre of mass was also located towards the target for the left-sided ball positions throughout the golf swing compared to the reference ball position, whereas the trend was reversed for the right-sided ball positions. We have concluded that initial ball position at address can cause a series of chain effects throughout the golf swing.

Finite Deformation Stiffness of Sliding Elastomeric Bearings

2011 ◽  
Vol 374-377 ◽  
pp. 1858-1862
Author(s):  
Jian Chun Xiao ◽  
Peng Liu ◽  
Ke Jian Ma
Keyword(s):  
Parametric Analysis ◽  
Steel Plates ◽  
Structural Behavior ◽  
Analysis Method ◽  
Force Vector ◽  
Elastomeric Bearings ◽  
Before And After ◽  
Bearing Stiffness ◽  
Vector Formula

Anchor bolts are set in some elastomeric bearings of large-span column-supported spatial steel roofs. Besides helping the bearing in-site assembly, the bolts play the roles of sliding position limitation and vertical anchorage. To analyze the effect of bearings on nonlinear structural behavior, the bearing stiffness change is studied just before and after the elastomer pad is in contact with the bolts. For the bearing that the pad is glued with the top/bottom steel plates, three kinds of relation of pad and bolts are discussed and an approximate horizontal stiffness formula is obtained with parametric analysis method. Based on the analysis results a stiffness expression for sliding elastomeric bearings is deduced. To solve the computational problem caused by the bearing stiffness changes, an improved imbalance force vector formula is proposed. Case study shows that the bolts have influence upon the computed results more significantly.

scholarly journals Associations between hoof shape and the position of the frontal plane ground reaction force vector in walking horses

2015 ◽  
Vol 64 (2) ◽  
pp. 76-81 ◽  
Author(s):  
GR Colborne ◽  
JE Routh ◽  
KR Weir ◽  
JE McKendry ◽  
E Busschers
Keyword(s):  
Ground Reaction Force ◽  
Reaction Force ◽  
Frontal Plane ◽  
Force Vector

scholarly journals Dynamic Asymmetries Do Not Match Spatiotemporal Step Asymmetries during Split-Belt Walking

Symmetry ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1089
Author(s):  
Stefano Scarano ◽  
Luigi Tesio ◽  
Viviana Rota ◽  
Valeria Cerina ◽  
Luigi Catino ◽  
...  
Keyword(s):  
Lower Limb ◽  
Step Length ◽  
Centre Of Mass ◽  
Mean Velocity ◽  
Rehabilitation Research ◽  
Joint Dynamics ◽  
Stance Time ◽  
After Effect ◽  
The Mean ◽  
Step Parameters

While walking on split-belt treadmills (two belts running at different speeds), the slower limb shows longer anterior steps than the limb dragged by the faster belt. After returning to basal conditions, the step length asymmetry is transiently reversed (after-effect). The lower limb joint dynamics, however, were not thoroughly investigated. In this study, 12 healthy adults walked on a force-sensorised split-belt treadmill for 15 min. Belts rotated at 0.4 m s−1 on both sides, or 0.4 and 1.2 m s−1 under the non-dominant and dominant legs, respectively. Spatiotemporal step parameters, ankle power and work, and the actual mean velocity of the body’s centre of mass (CoM) were computed. On the faster side, ankle power and work increased, while step length and stance time decreased. The mean velocity of the CoM slightly decreased. As an after-effect, modest converse asymmetries developed, fading within 2–5 min. These results may help to decide which belt should be assigned to the paretic and the unaffected lower limb when split-belt walking is applied for rehabilitation research in hemiparesis.

scholarly journals SPONTANEOUS CORRECTION OF EXTERNAL TIBIOFEMORAL ROTATION AND TIBIAL TUBEROSITY-TROCHLEAR GROOVE DISTANCE OCCURS AFTER MEDIAL PATELLOFEMORAL LIGAMENT RECONSTRUCTION IN FIXED OR OBLIGATORY DISLOCATORS

2021 ◽  
Vol 9 (7_suppl3) ◽  
pp. 2325967121S0013
Author(s):  
Alexandra H. Aitchison ◽  
Kenneth M. Lin ◽  
Daniel W. Green
Keyword(s):  
Patellar Instability ◽  
Ligament Reconstruction ◽  
Medial Patellofemoral Ligament ◽  
Extensor Mechanism ◽  
Tibial Tubercle ◽  
Trochlear Groove ◽  
Medial Patellofemoral Ligament Reconstruction ◽  
Force Vector ◽  
Tibiofemoral Rotation ◽  
The Mean

Background: Tibial tubercle to trochlear groove distance (TT-TG) and external tibiofemoral rotation (TFR) through the knee joint have been identified potential contributing factors to patellar instability. In patients with a fixed or obligatory lateral patella dislocation (FOD), the normal force vector of the extensor mechanism is altered, so instead of a direct axial pull to cause extension, it exerts a lateralizing and external rotatory force on the tibia via the tibial tubercle. Hypothesis/Purpose: The purpose of this study is to investigate postoperative changes in TT-TG and TFR after medial patellofemoral ligament reconstruction (MPFLR) in two clinical cohorts: standard traumatic patellar instability (SPI) patients and FOD patients. We hypothesized that by surgically relocating the patella in the trochlea, and re-establishing medial sided soft tissue tension, the increased medializing force vector on the patella may exert enough force to alter resting rotation of the tibia in relation to the femur in the FOD group. Methods: A retrospective study was performed from April 2009 to February 2019. FOD and SPI patients under 18 years with available magnetic resonance imaging (MRI) of the knee before and after MPFLR were eligible. All FOD patients in the time frame were analyzed and SPI patients were randomly selected. Exclusion criteria were outside institution MRI, concomitant alignment procedures done at the time of MPFLR, and prior MPFLR or tibial tubercle osteotomy. TT-TG and TFR (using the posterior femoral and tibial condylar lines) were measured blindly on initial axial MRI. Statistical analysis using a paired sample t-test was performed with significance set at p<0.05. Results: A total of 30 patients were included, 14 in the FOD group and 16 in the SPI group. The mean age at time of surgery was 13.9 years (range 10-17 years), 53% of the cohort was female, and the mean time from surgery to follow-up MRI was 2.0 years. Demographics by group are shown in Table 1. TT-TG and TFR were not significantly different preoperatively versus postoperatively in the SPI group (Table 2). In the FOD group, both TT-TG (17.7 vs 13.7, P=.019) and TFR (8.6 vs 3.1, P=.025) decreased significantly on postoperative MRI. Conclusion: The postoperative decrease in TT-TG and TFR in the FOD group suggests that MPFLR in fixed or obligatory dislocators can improve the external rotation deformity through the level of the joint, and thus may help normalize the forces acting through the extensor mechanism. Tables/ Figures [Table: see text][Table: see text]

scholarly journals Balancing on a narrow ridge: biomechanics and control

1999 ◽  
Vol 354 (1385) ◽  
pp. 869-875 ◽  
Author(s):  
E. Otten
Keyword(s):  
Hip Joint ◽  
Ground Reaction Force ◽  
Inverted Pendulum ◽  
Reaction Force ◽  
Angular Acceleration ◽  
Centre Of Mass ◽  
Inverted Pendulum Model ◽  
Pendulum Model ◽  
Narrow Ridge ◽  
Standing Humans

The balance of standing humans is usually explained by the inverted pendulum model. The subject invokes a horizontal ground–reaction force in this model and controls it by changing the location of the centre of pressure under the foot or feet. In experiments I showed that humans are able to stand on a ridge of only a few millimetres wide on one foot for a few minutes. In the present paper I investigate whether the inverted pendulum model is able to explain this achievement. I found that the centre of mass of the subjects sways beyond the surface of support, rendering the inverted pendulum model inadequate. Using inverse simulations of the dynamics of the human body, I found that hip–joint moments of the stance leg are used to vary the horizontal component of the ground–reaction force. This force brings the centre of mass back over the surface of support. The subjects generate moments of force at the hip–joint of the swing leg, at the shoulder–joints and at the neck. These moments work in conjunction with a hip strategy of the stance leg to limit the angular acceleration of the head–arm–trunk complex. The synchrony of the variation in moments suggests that subjects use a motor programme rather than long latency reflexes.

Mechanical power output during running accelerations in wild turkeys

2002 ◽  
Vol 205 (10) ◽  
pp. 1485-1494 ◽  
Author(s):  
Thomas J. Roberts ◽  
Jeffrey A. Scales
Keyword(s):  
Power Output ◽  
Ground Reaction Force ◽  
Center Of Mass ◽  
Reaction Force ◽  
Mechanical Power ◽  
Force Vector ◽  
Instantaneous Power ◽  
Hindlimb Muscle ◽  
Wild Turkeys ◽  
Running Mechanics

SUMMARYWe tested the hypothesis that the hindlimb muscles of wild turkeys(Meleagris gallopavo) can produce maximal power during running accelerations. The mechanical power developed during single running steps was calculated from force-plate and high-speed video measurements as turkeys accelerated over a trackway. Steady-speed running steps and accelerations were compared to determine how turkeys alter their running mechanics from a low-power to a high-power gait. During maximal accelerations, turkeys eliminated two features of running mechanics that are characteristic of steady-speed running: (i) they produced purely propulsive horizontal ground reaction forces, with no braking forces, and (ii) they produced purely positive work during stance, with no decrease in the mechanical energy of the body during the step. The braking and propulsive forces ordinarily developed during steady-speed running are important for balance because they align the ground reaction force vector with the center of mass. Increases in acceleration in turkeys correlated with decreases in the angle of limb protraction at toe-down and increases in the angle of limb retraction at toe-off. These kinematic changes allow turkeys to maintain the alignment of the center of mass and ground reaction force vector during accelerations when large propulsive forces result in a forward-directed ground reaction force. During the highest accelerations, turkeys produced exclusively positive mechanical power. The measured power output during acceleration divided by the total hindlimb muscle mass yielded estimates of peak instantaneous power output in excess of 400 W kg-1 hindlimb muscle mass. This value exceeds estimates of peak instantaneous power output of turkey muscle fibers. The mean power developed during the entire stance phase increased from approximately zero during steady-speed runs to more than 150 W kg-1muscle during the highest accelerations. The high power outputs observed during accelerations suggest that elastic energy storage and recovery may redistribute muscle power during acceleration. Elastic mechanisms may expand the functional range of muscle contractile elements in running animals by allowing muscles to vary their mechanical function from force-producing struts during steady-speed running to power-producing motors during acceleration.

Phase-Specific Force and Time Predictors of Standing Long Jump Distance

2021 ◽  
pp. 1-8
Author(s):  
John R. Harry ◽  
John Krzyszkowski ◽  
Luke D. Chowning ◽  
Kristof Kipp
Keyword(s):  
National Collegiate Athletic Association ◽  
Reaction Force ◽  
Vertical Force ◽  
Jump Height ◽  
Strength Index ◽  
Phase Duration ◽  
Standing Long Jump ◽  
Jump Distance ◽  
Long Jump ◽  
Force Time

This study sought to identify potential predictors of standing long jump (SLJ) performance using force–time strategy metrics within the unloading, eccentric yielding, eccentric braking, and concentric phases. Fifteen National Collegiate Athletic Association division 1 male soccer players (19 [1] y, 1.81 [0.94] m, 80.3 [22.4] kg) performed 3 maximum-effort SLJs, while 3-dimensional ground reaction force (GRF) data were obtained. Regularized regression models were used to investigate associations between force–time strategy metrics and 2 metrics of SLJ performance (ie, jump distance and modified reactive strength index). Jump height and eccentric yielding time were the only predictors of jump distance that also demonstrated large correlations to jump distance. Anterior–posterior unloading yank, average concentric vertical force, and concentric phase duration were the only predictors of modified reactive strength index that also demonstrated large correlations to modified reactive strength index. To maximize SLJ distance in high-level soccer athletes, human performance practitioners could design interventions to drive changes in strategy to increase jump height and decrease eccentric yielding time. To improve SLJ explosiveness, interventions to drive changes in unloading and concentric force application and decrease concentric time could be emphasized. Importantly, unique variable combinations can be targeted when training for SLJ distance and explosiveness adaptations.

scholarly journals Effect of Core Training Program on Physical Functional Performance in Female Soccer Players

2016 ◽  
Vol 9 (5) ◽  
pp. 115 ◽  
Author(s):  
Cengiz Taskin
Keyword(s):  
Functional Performance ◽  
Vertical Jump ◽  
Training Group ◽  
Soccer Players ◽  
Control Group ◽  
The Core ◽  
Standing Long Jump ◽  
Long Jump ◽  
The Mean ◽  
Core Training

<p class="apa">The purpose of this study was to determine the effect of core training program on speed, acceleration, vertical jump, and standing long jump in female soccer players. A total of 40 female soccer players volunteered to participate in this study. They were divided randomly into 1 of 2 groups: core training group (CTG; n = 20) and control group (CG; n = 20). The mean (SD) age was 19.05 ± 1.15 years, height was 160.60 ± 4.22 cm, weight was 56.45 ± 3.33 kg, and sport age was 4.50 ± 1.24 for the core training group; the mean (SD) age was 18.55 ± 0.76 years, height was 159.10 ± 3.86 cm, weight was 52.20 ± 3.60 kg, and sport age was 3.35 ± 0.75 years for the control group. Following randomization, the 2 groups did not differ significantly (p&gt;0.05) in any of the dependent variables. The subjects in the control group did not participate in the training and participated only in the pre- and posttest measurements. To evaluate the effect of core training over the functional performance, we applied a testing procedure that included measurements of speed, acceleration, vertical jump, and standing long jump. The core training group showed a 3.4%, 5.9%, 13.3%, 4.2% improvement in speed, acceleration, vertical jump, and standing long jump (respectively) (P&lt;0.05), whereas the control group did not change (P&gt;0.05). In conclusion, Core exercises were improved speed, acceleration, vertical jump, and standing long jump in 18-19 years-old female soccer players. Therefore, it is believed core training is necessary for optimal sport performance and should not be dismissed for all sport branches.</p>

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