scholarly journals A simple computational method to estimate stance velocity in running

2021 ◽  
Author(s):  
Geoffrey T. Burns ◽  
Ronald F. Zernicke
Keyword(s):  
Reaction Force ◽  
Simulation Models ◽  
Impact Angle ◽  
Computational Method ◽  
New Method ◽  
Leg Length ◽  
Reaction Forces ◽  
Vertical Ground ◽  
Vertical Ground Reaction Forces ◽  
Impact Angles

Running dynamical analyses typically approximate a runner's stance velocity as the average stride cycle velocity (the average running speed). That approximation necessarily overestimates stance velocity and biases subsequent results. Stance velocities are crucial in kinetic spring-mass analyses of running, where approximation of a runner's impact angle and calculation of leg stiffness require that input. Here, a new method is presented to approximate a runner's stance velocity via measurement of contact and flight times with the runner's average speed, leg length or height, and mass. This method accurately estimated stance velocities of simulated spring-mass systems across typical running speeds of 3.5-5.5 m/s (r>0.99) and more accurately estimated impact angles of simulations and leg stiffnesses. The method also accurately estimated peak horizontal vertical ground reaction forces across speeds (r=0.82), but the bias magnitude increased with speed. Robustness of the new method was further tested for runners at 2.5, 3.5, and 4.5 m/s, and the new method provided steeper impact angles than those from traditional estimates and correspondingly higher leg stiffnesses, analogous to the observations in the simulation models. Horizontal ground reaction force estimates were weakly correlated in braking and propulsion. They were improved by a corrective algorithm, but the intra- and inter-individual variation persisted. The directionality and magnitude of angle and stiffness estimates in the human runners were similar to simulations, suggesting the new method more accurately modeled runners’ spring-mass characteristics by using an accurate approximation of stance velocity. The new method can improve traditional kinetic analyses of running where stance velocity recordings are not captured with kinematic recordings and extend opportunities for accurate field-based analyses with limited measurement sources.

Factors Affecting Peak Vertical Ground Reaction Forces in Running

1986 ◽  
Vol 2 (1) ◽  
pp. 41-49 ◽  
Author(s):  
Edward C. Frederick ◽  
John L. Hagy
Keyword(s):  
Body Mass ◽  
Stride Length ◽  
Reaction Force ◽  
Step Length ◽  
Leg Length ◽  
Vertical Ground Reaction Force ◽  
Anthropometric Parameters ◽  
Factors Affecting ◽  
Reaction Forces ◽  
Vertical Ground

Nine subjects (6 males, 3 females) ranging in body mass from 90.9 to 45.5 kg ran repeated trials across a force platform while being filmed at 50 fps. The subjects ran five barefooted trials at each of three speeds: 3.35, 3.83, and 4.47 m · s−1. Force data were collected on-line and analyzed for the magnitude and temporal characteristics of the initial impact (Fz1) peak and the active (Fz2) peak of vertical ground reaction force (VGRF). Multiple regression and correlation analysis were used to study the relationship between the magnitudes of these kinetic data and kinematic and anthropometric data taken from the film and from measurements of the subjects. The results support the general conclusion that speed and, indirectly, body mass are significant effectors of the magnitudes of Fz1. In addition, other factors that correlate significantly with Fz1 are reciprocal ponderal index (RPI) and stature; half-stride length, step length, leg length, and vertical hip excursion during a half-stride cycle; and hip offset, contact angle, and dorsiflexion angle at contact. Body mass correlates highly with Fz2 (r = 0.95). Other significant factors correlating with Fz2 are RPI, stature, vertical hip excursion, dorsiflexion angle, hip offset, half-stride length, and step length. These data support earlier findings that speed and the effective mass of the leg at contact are important effectors of the magnitude of Fzl. In addition, the kinematic and anthropometric parameters that contribute significantly to the variability in Fzl and F are generally cross-correlated with body size and/or running speed.

scholarly journals In search of the pitching momentum that enables some lizards to sustain bipedal running at constant speeds

2013 ◽  
Vol 10 (84) ◽  
pp. 20130241 ◽  
Author(s):  
Sam Van Wassenbergh ◽  
Peter Aerts
Keyword(s):  
Reaction Force ◽  
Vertical Ground Reaction Force ◽  
Mass Model ◽  
Temporal Asymmetry ◽  
Long Time ◽  
Reaction Forces ◽  
Vertical Ground ◽  
Vertical Ground Reaction Forces ◽  
Angular Impulse ◽  
Force Profiles

The forelimbs of lizards are often lifted from the ground when they start sprinting. Previous research pointed out that this is a consequence of the propulsive forces from the hindlimbs. However, despite forward acceleration being hypothesized as necessary to lift the head, trunk and forelimbs, some species of agamids, teiids and basilisks sustain running in a bipedal posture at a constant speed for a relatively long time. Biomechanical modelling of steady bipedal running in the agamid Ctenophorus cristatus now shows that a combination of three mechanisms must be present to generate the angular impulse needed to cancel or oppose the effect of gravity. First, the trunk must be lifted significantly to displace the centre of mass more towards the hip joint. Second, the nose-up pitching moment resulting from aerodynamic forces exerted at the lizard's surface must be taken into account. Third, the vertical ground-reaction forces at the hindlimb must show a certain degree of temporal asymmetry with higher forces closer to the instant of initial foot contact. Such asymmetrical vertical ground-reaction force profiles, which differ from the classical spring-mass model of bipedal running, seem inherent to the windmilling, splayed-legged running style of lizards.

A Comparison of the Kinetic and Kinematic Characteristics of Plyometric Drop-Jump and Pendulum Exercises

1998 ◽  
Vol 14 (3) ◽  
pp. 260-275 ◽  
Author(s):  
Neil E. Fowler ◽  
Adrian Lees
Keyword(s):  
Training Stimulus ◽  
Reaction Force ◽  
Drop Jump ◽  
Coordination Strategies ◽  
Kinematic Characteristics ◽  
Drop Jumps ◽  
Reaction Forces ◽  
Cross Correlations ◽  
Vertical Ground ◽  
Vertical Ground Reaction Forces

The aim of this study was to compare the kinetic and kinematic characteristics of plyometric drop-jump and pendulum exercises. Exercises were filmed (100 Hz) from the sagittal view and manually digitized; the data were smoothed and differentiated using cross-validated quintic splines. Ground reaction force data were sampled using a Kistler force platform sampling at 500 Hz. Differences between movement amplitudes and coordination strategies were assessed usingttests and conjugate cross-correlations. Pendulum exercises involved a greater range of motion at the ankle and knee but less motion at the hip joint than drop-jumps. Although different in absolute terms, the exercises used a similar coordination strategy. Drop-jumps resulted in greater peak vertical ground reaction forces than the pendulum exercises although the latter involved a greater net impulse. The similarity between the movement patterns for the two modes of exercise led to the conclusion that pendulum exercises offer a training stimulus similar to that of drop-jumps.

scholarly journals The biomechanics of the fastest sprinter with a unilateral transtibial amputation

2018 ◽  
Vol 124 (3) ◽  
pp. 641-645 ◽  
Author(s):  
Owen N. Beck ◽  
Alena M. Grabowski
Keyword(s):  
Treadmill Running ◽  
Ground Reaction Forces ◽  
Functional Abilities ◽  
Leg Length ◽  
Transtibial Amputation ◽  
Leg Stiffness ◽  
Reaction Forces ◽  
Vertical Ground ◽  
Leg Amputation ◽  
Vertical Ground Reaction Forces

People have debated whether athletes with transtibial amputations should compete with nonamputees in track events despite insufficient information regarding how the use of running-specific prostheses (RSPs) affect athletic performance. Thus, we sought to quantify the spatiotemporal variables, ground reaction forces, and spring-mass mechanics of the fastest athlete with a unilateral transtibial amputation using an RSP to reveal how he adapts his biomechanics to achieve elite running speeds. Accordingly, we measured ground reaction forces during treadmill running trials spanning 2.87 to 11.55 m/s of the current male International Paralympic Committee T44 100- and 200-m world record holder. To achieve faster running speeds, the present study’s athlete increased his affected leg (AL) step lengths ( P < 0.001) through longer contact lengths ( P < 0.001) and his unaffected leg (UL) step lengths ( P < 0.001) through longer contact lengths ( P < 0.001) and greater stance average vertical ground reaction forces ( P < 0.001). At faster running speeds, step time decreased for both legs ( P < 0.001) through shorter ground contact and aerial times ( P < 0.001). Unlike athletes with unilateral transtibial amputations, this athlete maintained constant AL and UL stiffness across running speeds ( P ≥ 0.569). Across speeds, AL step lengths were 8% longer ( P < 0.001) despite 16% lower AL stance average vertical ground reaction forces compared with the UL ( P < 0.001). The present study’s athlete exhibited biomechanics that differed from those of athletes with bilateral and without transtibial amputations. Overall, we present the biomechanics of the fastest athlete with a unilateral transtibial amputation, providing insight into the functional abilities of athletes with transtibial amputations using running-specific prostheses.NEW & NOTEWORTHY The present study’s athlete achieved the fastest treadmill running trial ever attained by an individual with a leg amputation (11.55 m/s). From 2.87 to 11.55 m/s, the present study’s athlete maintained constant affected and unaffected leg stiffness, which is atypical for athletes with unilateral transtibial amputations. Furthermore, the asymmetric vertical ground reaction forces of athletes with unilateral transtibial amputations during running may be the result of leg length discrepancies.

Lower-Extremity-Joint Cryotherapy Does Not Affect Vertical Ground-Reaction Forces during Landing

2001 ◽  
Vol 10 (2) ◽  
pp. 132-142 ◽  
Author(s):  
Andrew G Jameson ◽  
Stephen J Kinzey ◽  
Jeffrey S Hallam
Keyword(s):  
Repeated Measures ◽  
Vertical Jump ◽  
Reaction Force ◽  
Vertical Ground Reaction Force ◽  
Physically Active ◽  
Before And After ◽  
Reaction Forces ◽  
Vertical Ground ◽  
Chronic Injuries ◽  
Vertical Ground Reaction Forces

Context:Cryotherapy is commonly used in the care of acute and chronic injuries. It decreases pain, reduces swelling, and causes vasoconstriction of blood vessels. Its detrimental effects on motor activity might predispose physically active individuals to further injury.Objective:To examine the effects of cryotherapy on vertical-ground-reaction-force (VGRF) during a 2-legged landing from a 2-legged targeted vertical jump.Design:2 × 4 MANOVA with repeated measures.Setting:Biomechanics laboratory.Participants:10 men, means: 22.40 ± 1.26 years, 76.01 ± 26.95 kg, 182.88 ± 6.88 cm.Intervention:VGRF during landing from a targeted vertical jump (90% of maximum) was measured before and after four 20-minute cryotherapy treatments.Results:There were no significant differences in VGRF as a result of cryotherapy.Conclusion:Under the constraints of this study there is no evidence that returning to activity immediately after cryotherapy predisposes an athlete to injury because of a change in VGRF.

scholarly journals The Role of Water-Based Exercise on Vertical Ground Reaction Forces in Overweight Children: A Pilot Study

Obesities ◽  
2021 ◽  
Vol 1 (3) ◽  
pp. 209-219
Author(s):  
Mariana Borba Gomes ◽  
Luana Siqueira Andrade ◽  
Gabriela Neves Nunes ◽  
Marina Krause Weymar ◽  
Gustavo Zaccaria Schaun ◽  
...  
Keyword(s):  
Aquatic Environment ◽  
Loading Rate ◽  
Reaction Force ◽  
Overweight Children ◽  
Vertical Ground Reaction Force ◽  
Safe Alternative ◽  
Running Exercise ◽  
Reaction Forces ◽  
Vertical Ground ◽  
Vertical Ground Reaction Forces

The aquatic environment represents an adequate and safe alternative for children with overweight to exercise. However, the magnitude of the vertical ground reaction force (Fz) during these exercises is unknown in this population. Therefore, our study aimed to compare the Fz during the stationary running exercise between the aquatic and land environments in children with overweight or obesity. The study is characterized as a cross-over study. Seven children, two with overweight and five with obesity (4 boys and 3 girls; 9.7 ± 0.8 years), performed two experimental sessions, one on land and another in the aquatic environment. In both conditions, each participant performed 15 repetitions of the stationary running exercise at three different cadences (60, 80, and 100 b min−1) in a randomized order. Their apparent weight was reduced by 72.1 ± 10.4% on average at the xiphoid process depth. The peak Fz, impulse, and loading rate were lower in the aquatic environment than on land (p < 0.001). Peak Fz was also lower at 80 b min−1 compared to 100 b min−1 (p = 0.005) and loading rate was higher at 100 b min−1 compared to 80 b min−1 (p = 0.003) and 60 b min−1 (p < 0.001) in the aquatic environment, whereas impulse was significantly reduced (p < 0.001) with the increasing cadence in both environments. It can be concluded that the aquatic environment reduces all the Fz outcomes investigated during stationary running and that exercise intensity seems to influence all these outcomes in the aquatic environment.

Comparison of Simultaneously Collected Kinetic Data with Force Plates and a Pressure Walkway

2018 ◽  
Vol 31 (05) ◽  
pp. 327-331 ◽  
Author(s):  
Gabriella Sandberg ◽  
Bryan Torres ◽  
Amanda Berjeski ◽  
Steven Budsberg
Keyword(s):  
Kinetic Data ◽  
Reaction Force ◽  
Vertical Force ◽  
Pressure Data ◽  
Vertical Ground Reaction Force ◽  
Reaction Forces ◽  
Pelvic Limb ◽  
Vertical Ground ◽  
Vertical Ground Reaction Forces ◽  
Collection Methods

Objective This article compares simultaneously collected kinetic data (percent limb distribution and limb symmetry) with force plates (FP) and a pressure walkway. Animals This study included 18 healthy client-owned adult dogs. Methods Vertical ground reaction force and pressure data were collected during two sessions 1 week apart (days 1 and 7) using both FP and pressure mat systems. Vertical ground reaction forces and vertical pressure data were each collected alone as well as simultaneously. A mixed effects model was used to test for differences in force, force percent data and symmetry indices (SI) that were calculated for the thoracic and pelvic limb pairs, between collection systems. A Pearson's correlation was used to test for correlations between force, force percentage and SI. Results There was no difference in peak vertical force (PVF) or total pressure index (TPI) data collected alone or when collected with pressure mat overlay the FP. Small but significant differences were found in percent limb distribution between PVF% and TPI%. Significant differences were found in the calculated SI for forelimbs and hindlimbs. Correlations between the PVF% and TPI% distribution were significant in both the fore- and hindlimbs. While there was a significant correlation between the forelimb SI, there was no significant correlation between the SI in the hindlimbs. Clinical Significance The method of calculating PVF and TPI percentages allowed for comparison between the collection methods. Significant differences were noted in the calculated SI between the collection methods and direct comparisons is not advisable.

Effect of starting distance on vertical ground reaction forces in the normal dog

2005 ◽  
Vol 18 (03) ◽  
pp. 183-185 ◽  
Author(s):  
D. DuLaney ◽  
T. Purinton ◽  
H. Dookwah ◽  
S. Budsberg
Keyword(s):  
Hind Limb ◽  
Reaction Force ◽  
Ground Reaction Forces ◽  
Test Field ◽  
Vertical Force ◽  
Body Type ◽  
Reaction Forces ◽  
Similar Weight ◽  
Vertical Ground ◽  
Vertical Ground Reaction Forces

SummaryThe purpose of this study was to evaluate the effect of starting distance on the peak vertical force (PVF) and associated vertical impulses (VI) of normal dogs. Five dogs of similar weight and body type were trotted at a velocity of 1.6–2.2 m/s from each of three starting distances; 2, 4, and 6 m, from the first plate in a two plate test field. A total of ten trials were recorded from each starting distance, five left first contacts and five right first contacts. Each ground reaction force (GRF) of interest was evaluated both within and between the three starting distances using a complete block ANOVA. There was not any significant effect of distance found on peak vertical forces in our study. However, distance did affect VI. Forelimb VI generated at a 2 m trot was significantly less than VI generated at a 6 m trot. Neither extreme distance was found to be significantly different than the 4 m VI. The VI of the hind limb was not significantly affected.

The Effect of External Ankle Support on Vertical Ground-Reaction Force and Lower Body Kinematics

2005 ◽  
Vol 14 (4) ◽  
pp. 301-312 ◽  
Author(s):  
Brad Hodgson ◽  
Laurie Tis ◽  
Steven Cobb ◽  
Elizabeth Higbie
Keyword(s):  
Statistical Analysis ◽  
Repeated Measures ◽  
Reaction Force ◽  
Vertical Ground Reaction Force ◽  
Kinematic Data ◽  
Ankle Angle ◽  
Reaction Forces ◽  
Vertical Ground ◽  
Ankle Support ◽  
Vertical Ground Reaction Forces

Objective:To examine the effects of external ankle support on vertical ground-reaction forces (VGRF) and kinematic data.Methods:Subjects completed 2 braced and 2 nonbraced 0.61-m hanging drop landings onto a force platform. Kinematic data were collected with 8 digital-optical cameras sampling at 120 Hz.Subjects:12 Division I female volleyball players.Statistical Analysis:A repeated-measures ANOVA with Bonferroni correction (P < .05) was used to determine whether significant differences existed between test conditions for peak VGRF, loading rate, hip angle, knee angle, and ankle angle at right-foot contact for peak 1 and peak 2 of the VGRF curve over the first 100 milliseconds of the landing phase, as well as total hip range of motion (ROM), total knee ROM, and total ankle ROM for the entire landing phase.Results:There were significant increases in peak P1 and LR1 and a significant decrease in ankle-angle change at right-foot contact in braced trials compared with the nonbraced condition.

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