Kinematics and Impulse Characteristics of Drop Landings from Three Heights

1991 ◽  
Vol 7 (2) ◽  
pp. 201-224 ◽  
Author(s):  
Jill L. McNitt-Gray
Keyword(s):  
Impact Velocity ◽  
Reaction Force ◽  
Force Plate ◽  
Recreational Athletes ◽  
Landing Impact ◽  
Reaction Forces ◽  
Joint Flexion ◽  
Collegiate Gymnasts ◽  
Impulse Characteristics ◽  
Force Data

During a landing impact, the human body is exposed to large forces and moments that create the potential for injury. To determine the effect of impact velocity and landing experience on the strategy selected, the preferred landing strategies used by male collegiate gymnasts and recreational athletes from three drop heights were characterized using mechanical descriptors. Kinematic and reaction force data were acquired simultaneously using highspeed film and a force plate. Reaction forces and lower extremity joint motion were used to characterize the strategies. Results indicated that statistically significant increases in joint flexion (with the exception of ankle joint flexion), angular velocity, and impact force resulted as impact velocity increased. Gymnasts and recreational athletes demonstrated similar adjustment patterns to increases in landing impact velocities; however, significant differences in degree of joint flexion, total landing phase time, and relative adjustments over impact velocity conditions were found.

Ground reaction force and hoof deceleration patterns on two different surfaces at the trot

2006 ◽  
Vol 3 (4) ◽  
pp. 209-216 ◽  
Author(s):  
Pia Gustås ◽  
Christopher Johnston ◽  
Stig Drevemo
Keyword(s):  
Ground Reaction Force ◽  
Reaction Force ◽  
Force Plate ◽  
Ground Surface ◽  
Ground Reaction Forces ◽  
Triaxial Accelerometer ◽  
Loading Rates ◽  
Sand Surface ◽  
Reaction Forces ◽  
Force Data

AbstractThe objective of the present study was to compare the hoof deceleration and ground reaction forces following impact on two different surfaces. Seven unshod Standardbreds were trotted by hand at 3.0–5.7 m s− 1 over a force plate covered by either of the two surfaces, sandpaper or a 1 cm layer of sand. Impact deceleration data were recorded from one triaxial accelerometer mounted on the fore- and hind hooves, respectively. Ground reaction force data were obtained synchronously from a force plate, sampled at 4.8 kHz. The differences between the two surfaces were studied by analysing representative deceleration and force variables for individual horses. The maximum horizontal peak deceleration and the loading rates of the vertical and the horizontal forces were significantly higher on sandpaper compared with the sand surface (P < 0.001). In addition, the initial vertical deceleration was significantly higher on sandpaper in the forelimb (P < 0.001). In conclusion, it was shown that the different qualities of the ground surface result in differences in the hoof-braking pattern, which may be of great importance for the strength of the distal horse limb also at slow speeds.

scholarly journals A biomechanical comparison of the SACH, Seattle and Jaipur feet using ground reaction forces

1995 ◽  
Vol 19 (1) ◽  
pp. 37-45 ◽  
Author(s):  
A. P. Arya ◽  
A. Lees ◽  
H. C. Nerula ◽  
L. Klenerman
Keyword(s):  
Developing Countries ◽  
Reaction Force ◽  
Force Plate ◽  
Biomechanical Properties ◽  
The Other ◽  
Ground Reaction Forces ◽  
Prosthetic Foot ◽  
Reaction Forces ◽  
Biomechanical Comparison ◽  
Force Data

The Jaipur prosthetic foot was developed in India in response to specific socio-cultural needs of Indian amputees. It is being used extensively in India and several other developing countries. Its claim of being a cheaper and satisfactory alternative to other prosthetic feet has not been investigated biomechanically. The present study was undertaken to compare its biomechanical properties with the SACH and Seattle feet, using ground reaction forces. Three trans-tibial amputees participated in the experiment which measured the ground reaction force data using a Kistler force plate. Subject's normal foot was used as a reference. Six variables from the vertical and anteroposterior components of ground reaction forces were quantified, their statistical analysis showed that the normal foot generates significantly larger ground reaction forces than the prosthetic foot. The shock absortion capacity of the SACH foot was found to be better when compared with the other two feet, while the Jaipur foot allowed a more natural gait and was closer in performance to the normal foot. None of the prostheses significantly influenced the locomotor style of the amputees.

Landing Strategies Used by Gymnasts on Different Surfaces

1994 ◽  
Vol 10 (3) ◽  
pp. 237-252 ◽  
Author(s):  
Jill L McNitt-Gray ◽  
Takashi Yokoi ◽  
Carl Millward
Keyword(s):  
Knee Flexion ◽  
Reaction Force ◽  
Peak Knee ◽  
Joint Solution ◽  
Joint Flexion ◽  
Collegiate Gymnasts ◽  
Total Body ◽  
Force Time ◽  
Hip Flexion ◽  
Impulse Characteristics

In this study, landing strategies of gymnasts were hypothesized to change with different landing surfaces. This hypothesis was tested by comparing the kinematics and reaction force-time characteristics of two-foot competition-style drop landings performed by male and female collegiate gymnasts onto three surfaces (soft mat, stiff mat, no mat). Significantly lower peak vertical forces, longer landing phase times, and greater knee and hip flexion were observed between the no mat condition and the mat conditions. Knee flexion and peak knee flexion velocities were also observed to be significantly greater for landings on the stiff mat than those on the soft mat. These results indicate that the gymnasts in this study modulated total body stiffness in response to changes in landing surface conditions by using a multi joint solution. In addition, the presence of a mat may reduce the need for joint flexion and may alter the vertical impulse characteristics experienced during landing.

The evaluation of limb symmetry indices using ground reaction forces collected with one or two force plates in healthy dogs

2017 ◽  
Vol 30 (01) ◽  
pp. 54-58 ◽  
Author(s):  
Gabby Sandberg ◽  
Sarah Robb ◽  
Steven Budsberg ◽  
Nicola Volstad
Keyword(s):  
Repeated Measures ◽  
Reaction Force ◽  
Force Plate ◽  
Ground Reaction Forces ◽  
Vertical Ground Reaction Force ◽  
Mean Values ◽  
Repeated Measures Analysis ◽  
Reaction Forces ◽  
Vertical Ground ◽  
Force Data

SummaryObjective: To compare the variability of symmetry indices within and between days when using one and two force plates for data collection.Animals: Seventeen healthy client-owned adult dogs.Methods: Vertical ground reaction force data were collected in a crossover study design, with four collection sessions on two consecutive days, and then two weeks apart (days 1, 2, 15, and 16) using both 1-plate and 2-plate collection methods. Symmetry indices were calculated for limb pairs using two standard equations (SI1 and SI2). Repeated measures analysis was used to compare symmetry indices data between plate systems and days. Significance was set at p <0.05.Results: There were no significant differences between plate systems for SI1 and SI2. There were no significant differences between data collected on different days and no significant interaction effects between variables. Symmetry indices were consistently larger for ground reaction forces calculated from non-consecutive footfalls.Conclusions: The use of two force plate systems will minimize variance caused by trial repetition and paired limb variation. When comparing SI1 to SI2, results were not significantly different. However, there were consistently higher mean values for SI1 compared with SI2 and symmetry indices were consistently larger for 1-plate systems compared to 2-plate systems for both symmetry indices.

Modification of the contact area of a standard force platform and runway for small breed dogs

2014 ◽  
Vol 27 (04) ◽  
pp. 257-262 ◽  
Author(s):  
J. Y. W. Kim ◽  
T. C. Garcia-Nolan ◽  
S. Y. Kim ◽  
K. Hayashi ◽  
P. L. Hitchens ◽  
...  
Keyword(s):  
Reaction Force ◽  
Force Plate ◽  
Force Platform ◽  
Standard Size ◽  
Plate Size ◽  
Propulsion Force ◽  
In Series ◽  
Reaction Forces ◽  
Wood Frame ◽  
Clinically Significant

SummaryObjectives: To develop a platform that used standard size force plates for large breed dogs to capture ground reaction force data from any size dog.Methods: A walkway platform was constructed to accommodate two force plates (60 cm x 40 cm) positioned in series to a variety of smaller sizes. It was constructed from a custom wood frame with thick aluminium sheet force plate covers that prevented transfer of load to the force plate, except for rectangular windows of three different dimensions. A friction study was performed to ensure plates did not translate relative to one another during gait trials. A prospective, observational, single crossover study design was used to compare the effect of force platform configuration (full plate size [original plate], half plate size [modified plate]) on ground reaction forces using eight adult healthy Labrador Retriever dogs.Results: Slippage of the steel plate on the force plate did not occur. Peak propulsion force was the only kinetic variable statistically different between the full size and half sized platforms. There were no clinically significant differences between the full and half force platforms for the variables and dogs studied.Discussion and conclusion: The modified force platform allows the original 60 x 40 cm force plate to be adjusted effectively to a 30 x 40 cm, 20 x 40 cm and 15 x 40 cm sized plate with no clinically significant change in kinetic variables. This modification that worked for large breed dogs will potentially allow kinetic analysis of a large variety of dogs with different stride lengths.

Correlation between Ground Reaction Force and Tibial Acceleration in Vertical Jumping

2007 ◽  
Vol 23 (3) ◽  
pp. 180-189 ◽  
Author(s):  
Niell G. Elvin ◽  
Alex A. Elvin ◽  
Steven P. Arnoczky
Keyword(s):  
Ground Reaction Force ◽  
Reaction Force ◽  
Force Plate ◽  
Coefficient Of Determination ◽  
Ground Reaction Forces ◽  
Accelerometer Data ◽  
Jump Height ◽  
Vertical Jumping ◽  
Average Coefficient ◽  
Reaction Forces

Modern electronics allow for the unobtrusive measurement of accelerations outside the laboratory using wireless sensor nodes. The ability to accurately measure joint accelerations under unrestricted conditions, and to correlate them with jump height and landing force, could provide important data to better understand joint mechanics subject to real-life conditions. This study investigates the correlation between peak vertical ground reaction forces, as measured by a force plate, and tibial axial accelerations during free vertical jumping. The jump heights calculated from force-plate data and accelerometer measurements are also compared. For six male subjects participating in this study, the average coefficient of determination between peak ground reaction force and peak tibial axial acceleration is found to be 0.81. The coefficient of determination between jump height calculated using force plate and accelerometer data is 0.88. Data show that the landing forces could be as high as 8 body weights of the jumper. The measured peak tibial accelerations ranged up to 42 g. Jump heights calculated from force plate and accelerometer sensors data differed by less than 2.5 cm. It is found that both impact accelerations and landing forces are only weakly correlated with jump height (the average coefficient of determination is 0.12). This study shows that unobtrusive accelerometers can be used to determine the ground reaction forces experienced in a jump landing. Whereas the device also permitted an accurate determination of jump height, there was no correlation between peak ground reaction force and jump height.

Relationships Between Arch Height Flexibility and Medial–Lateral Ground Reaction Forces in Rearfoot and Forefoot Strike Runners

2020 ◽  
pp. 1-4
Author(s):  
Caleb D. Johnson ◽  
Irene S. Davis
Keyword(s):  
Military Personnel ◽  
Statistical Significance ◽  
Reaction Force ◽  
Small Sample ◽  
Arch Height ◽  
Lateral Forces ◽  
Reaction Forces ◽  
Recreational Runners ◽  
The Difference ◽  
Force Data

Higher medial–lateral forces have been reported in individuals with stiffer foot arches. However, this was in a small sample of military personnel who ran with a rearfoot strike pattern. Therefore, our purpose was to investigate whether runners, both rearfoot and forefoot strikers, show different associations between medial–lateral forces and arch stiffness. A group of 118 runners (80 rearfoot strikers and 38 forefoot strikers) were recruited. Ground reaction force data were collected during running on an instrumented treadmill. Arch flexibility was assessed as the difference in arch height from sitting to standing positions, and participants were classified into stiff/flexible groups. Group comparisons were performed for the ratio of medial:vertical and lateral:vertical impulses. In rearfoot strikers, runners with stiff arches demonstrated significantly higher medial:vertical impulse ratios (P = .036). Forefoot strikers also demonstrated higher proportions of medial forces; however, the mean difference did not reach statistical significance (P = .084). No differences were detected in the proportion of lateral forces between arch flexibility groups. Consistent with previous findings in military personnel, our results indicate that recreational runners with stiffer arches have a higher proportion of medial forces. Therefore, increasing foot flexibility may increase the ability to attenuate medial forces.

Measurement differences between three versus five photocells during collection of ground reaction forces in dogs

2007 ◽  
Vol 02 (02) ◽  
pp. 98-101 ◽  
Author(s):  
J. P. Punke ◽  
A. L. Speas ◽  
L. R. Reynolds ◽  
C. M. Andrews ◽  
S. C. Budsberg
Keyword(s):  
Ground Reaction Force ◽  
Reaction Force ◽  
False Negative ◽  
False Negative Rate ◽  
Second Phase ◽  
False Negatives ◽  
Two Systems ◽  
Reaction Forces ◽  
Force Data ◽  
Gathering Data

SummaryThe differences between velocities and accelerations obtained from three and five photocells were examined when obtaining ground reaction force (GRF) data in dogs. Ground reaction force data was collected 259 times from 16 different dogs in two experimental phases. The first phase compared velocities and accelerations reported by the two systems based on trials accepted by the three photocell system. The second phase accepted trials based on data from five photocells. Three photocell data were calculated mathematically in the second phase in order to compare the values of both systems. The velocity and acceleration values obtained from each system were significantly different (at the hundredth of a meter per second). Differences in measured values did not result in acceptance of data by the three photocell system that would not have been acceptable with the five photocell system (false positives), but did result in rejection of acceptable data by the three photocell system (11% false negative rate). Given the small differences between the two systems, GRF data collected should not be significantly different, though the three photocell system is less efficient in gathering data due to the number of trials rejected as false negatives.

Abstract 482: Differences in Ground Reaction Forces and Chest Compression Release Velocity in Professional and Lay Rescuers With and Without the Use of Real-Time CPR Feedback

Circulation ◽  
2019 ◽  
Vol 140 (Suppl_2) ◽  
Author(s):  
Lyra Clark ◽  
Ben Senderling ◽  
Jeff R Gould ◽  
Chris Kaufman ◽  
Nick Stergiou
Keyword(s):  
Real Time ◽  
Chest Compression ◽  
Reaction Force ◽  
Force Plate ◽  
Compression Cycle ◽  
Reaction Forces ◽  
Force Range ◽  
Favorable Neurological Outcome ◽  
Compression Characteristics ◽  
Pearson Correlations

Purpose: Chest compression release velocity (CCRV) has been associated with survival and favorable neurological outcome after cardiac resuscitation. Both complete chest release and high CCRV contribute to improved venous return during CPR. Differences in compression forces delivered by professional and lay rescuers are reported, which may contribute to differences in CCRV. The aim of this pilot study was to investigate differences in ground reaction force (GRF) and CCRV between professional and lay rescuers during CPR performed on a manikin with and without real-time feedback. Methods: Professional (n = 5) and lay rescuers (n = 11) performed two minutes of continuous compressions on a manikin positioned over a force plate for two trials. CPR feedback provided by a defibrillator was disabled in the first trial and enabled in the second. CPR pads containing an accelerometer were used to calculate individual compression characteristics. Relative maximum and minimum GRFs were calculated for each compression cycle and averaged over each trial. Paired and independent sample t tests and Pearson correlations were conducted in STATA 15.1. Results: CCRV was higher in professionals vs. lay rescuers with feedback disabled and enabled ( p <0.05). Professionals had greater maximal and lower minimum forces than lay rescuers without feedback ( p <0.05), though there were no differences between groups with feedback enabled (Table 1). CCRV was associated with minimum force (r = -0.63, p <0.01) and force range (r = 0.78, p <0.01) in all rescuers. Analysis of GRFs by CCRV for all rescuers indicated lower force minimum (9.71 + 3.16 N, p <0.05) with CCRV >400 mm/s in comparison to CCRV 300-400 mm/s (39.73 + 8.91 N) and CCRV 200-300 mm/s (63.82 + 16.98 N). Conclusions: CPR feedback attenuated differences in GRF between professional and lay rescuers. CCRV was greater in professionals and was associated with measures of GRF, and thus may serve as an indicator of both velocity and amount of chest release.

Computer Simulation of Kinetics Relationship between Gymnast and Mat

2014 ◽  
Vol 1044-1045 ◽  
pp. 1693-1696
Author(s):  
Xiao Fei Xiao ◽  
Wei Ya Hao
Keyword(s):  
Computer Simulation ◽  
Ground Reaction Force ◽  
Reaction Force ◽  
Specific Model ◽  
Vertical Ground Reaction Force ◽  
Time To Peak ◽  
Landing Impact ◽  
Reaction Forces ◽  
Different Characteristics ◽  
Landing Mat

Landing mats are essential for the safe completion of landing impact in gymnastics. Shock absorption and stability during landing impact is provided by both gymnasts’ ability and mat properties. The aim is to determine the influence of different characteristics of mat on mat-ground reaction forces. A subject-specific model with 12 segments rigid body and a model about landing mat in floor exercise were developed by computer simulation. The stiffness and dampness of landing mat influenced the peak of vertical ground reaction force and time to peak, but there were significant correlations between the friction of landing mat and the peak of horizontal ground reaction force and time to peak.

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