scholarly journals Acute Effects of Handheld Loading on Standing Broad Jump in Youth Athletes

2021 ◽  
Vol 18 (9) ◽  
pp. 5046
Author(s):  
Wei-Hsun Tai ◽  
Ray-Hsien Tang ◽  
Chen-Fu Huang ◽  
Shin-Liang Lo ◽  
Yu-Chi Sung ◽  
...  
Keyword(s):  
High Speed ◽  
Center Of Mass ◽  
Reaction Force ◽  
Sampling Rate ◽  
Random Order ◽  
Horizontal Distance ◽  
Acute Effects ◽  
Vertical Ground Reaction Force ◽  
Strength And Conditioning ◽  
Peak Knee

The study aimed to investigate the acute effects of handheld loading on standing broad jump (SBJ) performance and biomechanics. Fifteen youth male athletes (mean age: 14.7 ± 0.9 years; body mass: 59.3 ± 8.0 kg; height: 1.73 ± 0.07 m) volunteered to participate in the study. Participants were assigned to perform SBJ with and without 4 kg dumbbells in a random order. Kinematic and kinetic data were collected using 10 infrared high-speed motion-capture cameras at a 250 Hz sampling rate and two force platforms at a 1000 Hz sampling rate. A paired t-test was applied to all variables to determine the significance between loading and unloading SBJs. Horizontal distance (p < 0.001), take-off distance (p = 0.001), landing distance (p < 0.001), horizontal velocity of center of mass (CoM; p < 0.001), push time (p < 0.001), vertical impulse (p = 0.003), and peak horizontal and vertical ground reaction force (GRF; p < 0.001, p = 0.017) were significantly greater in loading SBJ than in unloading SBJ. The take-off vertical velocity of CoM (p = 0.001), take-off angle (p < 0.001), peak knee and hip velocity (p < 0.001, p = 0.007), peak ankle and hip moment (p = 0.006, p = 0.011), and peak hip power (p = 0.014) were significantly greater in unloading SBJ than in loading SBJ. Conclusions: Acute enhancement in SBJ performance was observed with handheld loading. The present findings contribute to the understanding of biomechanical differences in SBJ performance with handheld loading and are highly applicable to strength and conditioning training for athletes.

Effect of Hopping Frequency on Bilateral Differences in Leg Stiffness

2013 ◽  
Vol 29 (1) ◽  
pp. 55-60 ◽  
Author(s):  
Hiroaki Hobara ◽  
Koh Inoue ◽  
Kazuyuki Kanosue
Keyword(s):  
Ground Reaction Force ◽  
Center Of Mass ◽  
Reaction Force ◽  
Human Movement ◽  
Vertical Ground Reaction Force ◽  
Mass Model ◽  
Lower Extremity Injuries ◽  
Leg Stiffness ◽  
Significant Difference ◽  
Bilateral Differences

Understanding the degree of leg stiffness during human movement would provide important information that may be used for injury prevention. In the current study, we investigated bilateral differences in leg stiffness during one-legged hopping. Ten male participants performed one-legged hopping in place, matching metronome beats at 1.5, 2.2, and 3.0 Hz. Based on a spring-mass model, we calculated leg stiffness, which is defined as the ratio of maximal ground reaction force to maximum center of mass displacement at the middle of the stance phase, measured from vertical ground reaction force. In all hopping frequency settings, there was no significant difference in leg stiffness between legs. Although not statistically significant, asymmetry was the greatest at 1.5 Hz, followed by 2.2 and 3.0 Hz for all dependent variables. Furthermore, the number of subjects with an asymmetry greater than the 10% criterion was larger at 1.5 Hz than those at 2.2 and 3.0 Hz. These results will assist in the formulation of treatment-specific training regimes and rehabilitation programs for lower extremity injuries.

Mechanics of a rapid running insect: two-, four- and six-legged locomotion

1991 ◽  
Vol 156 (1) ◽  
pp. 215-231 ◽  
Author(s):  
R. J. Full ◽  
M. S. Tu
Keyword(s):  
Periplaneta Americana ◽  
Mechanical Energy ◽  
Center Of Mass ◽  
Reaction Force ◽  
Metabolic Cost ◽  
Legged Locomotion ◽  
American Cockroach ◽  
Stride Frequency ◽  
Gravitational Potential Energy ◽  
Vertical Ground Reaction Force

To examine the effects of variation in body form on the mechanics of terrestrial locomotion, we used a miniature force platform to measure the ground reaction forces of the smallest and, relative to its mass, one of the fastest invertebrates ever studied, the American cockroach Periplaneta americana (mass = 0.83 g). From 0.44-1.0 ms-1, P. americana used an alternating tripod stepping pattern. Fluctuations in gravitational potential energy and horizontal kinetic energy of the center of mass were nearly in phase, characteristic of a running or bouncing gait. Aerial phases were observed as vertical ground reaction force approached zero at speeds above 1 ms-1. At the highest speeds (1.0-1.5 ms-1 or 50 body lengths per second), P. americana switched to quadrupedal and bipedal running. Stride frequency approached the wing beat frequencies used during flight (27 Hz). High speeds were attained by increasing stride length, whereas stride frequency showed little increase with speed. The mechanical power used to accelerate the center of mass increased curvilinearly with speed. The mass-specific mechanical energy used to move the center of mass a given distance was similar to that measured for animals five orders of magnitude larger in mass, but was only one-hundredth of the metabolic cost.

scholarly journals Kinematics of Usain Bolt’s maximal sprint velocity

Kinesiology ◽  
2018 ◽  
Vol 50 (2) ◽  
pp. 172-180 ◽  
Author(s):  
Milan Čoh ◽  
Kim Hébert-Losier ◽  
Stanko Štuhec ◽  
Vesna Babić ◽  
Matej Supej
Keyword(s):  
Ground Reaction Force ◽  
High Speed ◽  
Reaction Force ◽  
Vertical Displacement ◽  
Biomechanical Analysis ◽  
Maximal Velocity ◽  
Vertical Ground Reaction Force ◽  
Mean Velocity ◽  
Vertical Ground ◽  
Sprint Velocity

This study investigated the maximal sprint velocity kinematics of the fastest 100 m sprinter, Usain Bolt. Two high-speed video cameras recorded kinematics from 60 to 90 m during the men 100 m final at the IAAF World Challenge Zagreb 2011, Croatia. Despite a relatively slow reaction time (194 ms), Bolt won in 9.85 s (mean velocity: 10.15 m/s). His fastest 20-m section velocity was 12.14 m/s, reached between 70 and 90 m, by 2.70-m long strides and 4.36 strides/s frequency. At the maximal velocity, his contact and flight times were 86 and 145 ms, respectively, and vertical ground reaction force generated equalled 4.2 times his body weight (3932 N). The braking and propulsion phase represented 37% and 63% of ground contact, respectively, with his centre of mass (CoM) exhibiting minor reductions in horizontal velocity (2.7%) and minimal vertical displacement (4.9 cm). Emerged Bolt’s maximal sprint velocity and international predominance from coordinated motor abilities, power generation capacities, and effective technique. This study confirms that his maximal velocity was achieved by means of relatively long strides, minimal braking phase, high vertical ground reaction force, and minimal vertical displacement of CoM. This study is the first in-depth biomechanical analysis of Bolt’s maximal sprinting velocity with the segmental reconstruction.

EVALUATION OF A COMPUTER-SIMULATION MODEL FOR HUMAN AMBULATION ON STILTS

2004 ◽  
Vol 04 (03) ◽  
pp. 283-303 ◽  
Author(s):  
CHRISTOPHER S. PAN ◽  
KIMBERLY M. MILLER ◽  
SHARON CHIOU ◽  
JOHN Z. WU
Keyword(s):  
Computer Simulation ◽  
Ground Reaction Force ◽  
Center Of Mass ◽  
Reaction Force ◽  
Construction Workers ◽  
Whole Body ◽  
Vertical Ground Reaction Force ◽  
Actual Measurement ◽  
Increased Risk ◽  
Vertical Ground

Stilts are elevated tools that are frequently used by construction workers to raise workers 18 to 40 inches above the ground without the burden of erecting scaffolding or a ladder. Some previous studies indicated that construction workers perceive an increased risk of injury when working on stilts. However, no in-depth biomechanical analyses have been conducted to examine the fall risks associated with the use of stilts. The objective of this study is to evaluate a computer-simulation stilts model. Three construction workers were recruited for walking tasks on 24-inch stilts. The model was evaluated using whole body center of mass and ground reaction forces. A PEAK™ motion system and two Kistler™ force platforms were used to collect data on both kinetic and kinematic measures. Inverse- and direct-dynamics simulations were performed using a model developed using commercial software — ADAMS and LifeMOD. For three coordinates (X, Y, Z) of the center of mass, the results of univariate analyses indicated very small variability for the mean difference between the model predictions and the experimental measurements. The results of correlation analyses indicated similar trends for the three coordinates. Plotting the resultant and vertical ground reaction force for both right and left feet showed small discrepancies, but the overall shape was identical. The percentage differences between the model and the actual measurement for three coordinates of the center of mass, as well as resultant and vertical ground reaction force, were within 20%. This newly-developed stilt walking model may be used to assist in improving the design of stilts.

Acute exposure to foot orthoses affects joint stiffness characteristics in recreational male runners

2015 ◽  
Vol 11 (3) ◽  
pp. 183-190 ◽  
Author(s):  
P.J. Taylor ◽  
H. Vincent ◽  
S. Atkins ◽  
J. Sinclair
Keyword(s):  
Sagittal Plane ◽  
Reaction Force ◽  
Joint Stiffness ◽  
Knee Extensor ◽  
Foot Orthoses ◽  
Vertical Ground Reaction Force ◽  
Mass Model ◽  
Peak Knee ◽  
Recreational Runners ◽  
Stiffness Characteristics

Commercially available foot orthoses are advocated for the treatment of chronic running injuries, such as patellofemoral pain, yet the mechanisms behind their effects are not well understood. This study aimed to examine the limb and joint stiffness characteristics when running with and without orthotics. Twelve recreational runners ran at 4.0 m/s. Limb stiffness was obtained using a spring-mass model of running by dividing the peak vertical ground reaction force (GRF) by the amount of limb compression. Knee and ankle joint stiffness’s were calculated by dividing the peak sagittal plane joint moment by the joint angular excursion. Differences between orthotic and non-orthotic running conditions were contrasted using paired samples t-tests. The results indicate that both peak knee extensor moment (orthotic = 2.74±0.57 and no-orthotic = 3.12±0.62 Nm/kg) and knee stiffness (orthotic = 5.56±1.08 and no-orthotic = 6.47±1.40 Nm/kg rad) were significantly larger when running without orthotics. This study may give further insight into the mechanical effects of commercially available foot orthoses. The current investigation provides some evidence to suggest that orthoses may be able to improve patellofemoral pathologies in recreational runners although further investigation is required.

Measuring only hop distance during single leg hop testing is insufficient to detect deficits in knee function after ACL reconstruction: a systematic review and meta-analysis

2019 ◽  
Vol 54 (3) ◽  
pp. 139-153 ◽  
Author(s):  
Argyro Kotsifaki ◽  
Vasileios Korakakis ◽  
Rod Whiteley ◽  
Sam Van Rossom ◽  
Ilse Jonkers
Keyword(s):  
Systematic Review ◽  
Acl Reconstruction ◽  
Knee Flexion ◽  
Meta Analysis ◽  
Grey Literature ◽  
Reaction Force ◽  
Knee Function ◽  
Cochrane Library ◽  
Vertical Ground Reaction Force ◽  
Peak Knee

ObjectiveTo systematically review the biomechanical deficits after ACL reconstruction (ACLR) during single leg hop for distance (SLHD) testing and report these differences compared with the contralateral leg and with healthy controls.DesignSystematic review with meta-analysis.Data sourcesA systematic search in Pubmed (Ovid), EMBASE, CINAHL, Scopus, Web of Science, PEDro, SPORTDiscus, Cochrane Library, grey literature and trial registries, was conducted from inception to 1 April 2018.Eligibility criteria for selecting studiesStudies reporting kinematic, kinetic and/or electromyographic data of the ACLR limb during SLHD with no language limits.ResultsThe literature review yielded 1551 articles and 19 studies met the inclusion criteria. Meta-analysis revealed strong evidence of lower peak knee flexion angle and knee flexion moments during landing compared with the uninjured leg and with controls. Also, moderate evidence (with large effect size) of lower knee power absorption during landing compared with the uninjured leg. No difference was found in peak vertical ground reaction force during landing. Subgroup analyses revealed that some kinematic variables do not restore with time and may even worsen.ConclusionDuring SLHD several kinematic and kinetic deficits were detected between limbs after ACLR, despite adequate SLHD performance. Measuring only hop distance, even using the healthy leg as a reference, is insufficient to fully assess knee function after ACLR.PROSPERO trial registration number CRD42018087779.

scholarly journals A Review of Biomechanical Gait Classification with Reference to Collected Trot, Passage and Piaffe in Dressage Horses

Animals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 763 ◽  
Author(s):  
Clayton ◽  
Hobbs
Keyword(s):  
Ground Reaction Force ◽  
Inverted Pendulum ◽  
Center Of Mass ◽  
Reaction Force ◽  
Vertical Ground Reaction Force ◽  
Phase Duration ◽  
Hind Limbs ◽  
Limb Loading ◽  
Vertical Ground ◽  
Lift Off

Gaits are typically classified as walking or running based on kinematics, the shape of the vertical ground reaction force (GRF) curve, and the use of inverted pendulum or spring-mass mechanics during the stance phase. The objectives of this review were to describe the biomechanical characteristics that differentiate walking and running gaits, then apply these criteria to classify and compare the enhanced natural gait of collected trot with the artificial gaits of passage and piaffe as performed by highly trained dressage horses. Limb contact and lift off times were used to determine contact sequence, limb phase, duty factor, and aerial phase duration. Ground reaction force data were plotted to assess fore and hind limb loading patterns. The center of mass (COM) trajectory was evaluated in relation to changes in potential and kinetic energy to assess the use of inverted pendulum and spring-mass mechanics. Collected trot and passage were classified as running gaits according to all three criteria whereas piaffe appears to be a hybrid gait combining walking kinematics with running GRFs and COM mechanics. The hind limbs act as springs and show greater limb compression in passage and piaffe compared with trot, whereas the forelimbs behave more like struts showing less compression in passage and piaffe than in trot.

Enhanced Performance With Elastic Resistance During the Eccentric Phase of a Countermovement Jump

2013 ◽  
Vol 8 (2) ◽  
pp. 181-187 ◽  
Author(s):  
Saied Jalal Aboodarda ◽  
Ashril Yusof ◽  
N.A. Abu Osman ◽  
Martin W. Thompson ◽  
A. Halim Mokhtar
Keyword(s):  
Power Output ◽  
High Speed ◽  
Tensile Force ◽  
Reaction Force ◽  
Jump Height ◽  
Vertical Ground Reaction Force ◽  
Jump Performance ◽  
Leg Stiffness ◽  
Significant Difference ◽  
Infrared Cameras

Purpose:To identify the effect of additional elastic force on the kinetic and kinematic characteristics, as well as the magnitude of leg stiffness, during the performance of accentuated countermovement jumps (CMJs).Methods:Fifteen trained male subjects performed 3 types of CMJ including free CMJ (FCMJ; ie, body weight), ACMJ-20, and ACMJ-30 (ie, accentuated eccentric CMJ with downward tensile force equivalent to 20% and 30% body mass, respectively). A force platform synchronized with 6 high-speed infrared cameras was used to measure vertical ground-reaction force (VGRF) and displacement.Results:Using downward tensile force during the lowering phase of a CMJ and releasing the bands at the start of the concentric phase increased maximal concentric VGRF (6.34%), power output (23.21%), net impulse (16.65%), and jump height (9.52%) in ACMJ-30 compared with FCMJ (all P < .05). However, no significant difference was observed in the magnitude of leg stiffness between the 3 modes of jump. The results indicate that using downward recoil force of the elastic material during the eccentric phase of a CMJ could be an effective method to enhance jump performance by applying a greater eccentric loading on the parallel and series elastic components coupled with the release of stored elastic energy.Conclusions:The importance of this finding is related to the proposition that power output, net impulse, takeoff velocity, and jump height are the key parameters for successful athletic performance, and any training method that improves impulse and power production may improve sports performance, particularly in jumping aspects of sport.

A treadmill-mounted force platform

1989 ◽  
Vol 67 (4) ◽  
pp. 1692-1698 ◽  
Author(s):  
R. Kram ◽  
A. J. Powell
Keyword(s):  
Full Range ◽  
Center Of Mass ◽  
Reaction Force ◽  
Vertical Displacement ◽  
The Body ◽  
Force Platform ◽  
Vertical Force ◽  
Vertical Ground Reaction Force ◽  
Contact Phase ◽  
Frictional Forces

Muscle, bone, and tendon forces; the movement of the center of mass, and the spring properties of the body during terrestrial locomotion can be measured using ground-mounted force platforms. These measurements have been extremely time consuming because of the difficulty in obtaining repeatable constant speed trials (particularly with animals). We have overcome this difficulty by mounting a force platform directly under the belt of a motorized treadmill. With this arrangement, vertical force can be recorded from an unlimited number of successive ground contacts in a much shorter time. With this treadmill-mounted force platform it is possible to accurately make the following measurements over the full range of steady speeds and under various perturbations of normal gait: 1) vertical ground reaction force over the course of the contact phase; 2) peak forces in bone, muscle, and tendon; 3) the vertical displacement of the center of mass; and 4) contact time for the limbs. In our treadmill-force platform design, belt forces and frictional forces cause no measurable cross-talk problem. Natural frequency (160 Hz), nonlinearity (less than 5%), and position independence (less than 2%) are all quite acceptable. Motor-caused vibrations are greater than 150 Hz and thus can be easily filtered.

scholarly journals Evaluation of a Kinematically-Driven Finite Element Footstrike Model

2016 ◽  
Vol 32 (3) ◽  
pp. 301-305 ◽  
Author(s):  
Iain Hannah ◽  
Andy Harland ◽  
Dan Price ◽  
Heiko Schlarb ◽  
Tim Lucas
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Center Of Pressure ◽  
Reaction Force ◽  
Element Model ◽  
Mechanical Tests ◽  
Vertical Ground Reaction Force ◽  
Dynamic Finite Element ◽  
Tetrahedral Elements ◽  
Vertical Ground

A dynamic finite element model of a shod running footstrike was developed and driven with 6 degree of freedom foot segment kinematics determined from a motion capture running trial. Quadratic tetrahedral elements were used to mesh the footwear components with material models determined from appropriate mechanical tests. Model outputs were compared with experimental high-speed video (HSV) footage, vertical ground reaction force (GRF), and center of pressure (COP) excursion to determine whether such an approach is appropriate for the development of athletic footwear. Although unquantified, good visual agreement to the HSV footage was observed but significant discrepancies were found between the model and experimental GRF and COP readings (9% and 61% of model readings outside of the mean experimental reading ± 2 standard deviations, respectively). Model output was also found to be highly sensitive to input kinematics with a 120% increase in maximum GRF observed when translating the force platform 2 mm vertically. While representing an alternative approach to existing dynamic finite element footstrike models, loading highly representative of an experimental trial was not found to be achievable when employing exclusively kinematic boundary conditions. This significantly limits the usefulness of employing such an approach in the footwear development process.

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