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.

Keyboard Reaction Force and Finger Flexor Electromyograms during Computer Keyboard Work

1996 ◽  
Vol 38 (4) ◽  
pp. 654-664 ◽  
Author(s):  
Bernard J. Martin ◽  
Thomas J. Armstrong ◽  
James A. Foulke ◽  
Sivakumaran Natarajan ◽  
Edward Klinenberg ◽  
...  
Keyword(s):  
Reaction Force ◽  
Voluntary Contraction ◽  
Force Measurements ◽  
Reaction Forces ◽  
Linear Fit ◽  
Finger Forces ◽  
The Difference ◽  
The Relationship ◽  
Force Data ◽  
Typing Task

This study examines the relationship between forearm EMGs and keyboard reaction forces in 10 people during keyboard tasks performed at a comfortable speed. A linear fit of EMG force data for each person and finger was calculated during static fingertip loading. An average r2 of .71 was observed for forces below 50% of the maximal voluntary contraction (MVC). These regressions were used to characterize EMG data in force units during the typing task. Averaged peak reaction forces measured during typing ranged from 3.33 N (thumb) to 1.84 N (little finger), with an overall average of 2.54 N, which represents about 10% MVC and 5.4 times the key switch make force (0.47 N). Individual peak or mean finger forces obtained from EMG were greater (1.2 to 3.2 times) than force measurements; hence the range of r2 for EMG force was .10 to .46. A closer correspondence between EMG and peak force was obtained using EMG averaged across all fingers. For 5 of the participants the force computed from EMG was within ±20% of the reaction force. For the other 5 participants forces were overestimated. For 9 participants the difference between EMG estimated force and the reaction force was less than 13% MVC. It is suggested that the difference between EMG and finger force partly results from the amount of muscle load not captured by the measured applied force.

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.

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.

scholarly journals Principal Component Analysis of the Running Ground Reaction Forces With Different Speeds

2021 ◽  
Vol 9 ◽  
Author(s):  
Lin Yu ◽  
Qichang Mei ◽  
Liangliang Xiang ◽  
Wei Liu ◽  
Nur Ikhwan Mohamad ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Loading Rate ◽  
Reaction Force ◽  
Principal Component ◽  
Component Analysis ◽  
Heel Strike ◽  
Impact Peak ◽  
Reaction Forces ◽  
The Difference ◽  
Second Peak

Ground reaction force (GRF) is a key metric in biomechanical research, including parameters of loading rate (LR), first impact peak, second impact peak, and transient between first and second impact peaks in heel strike runners. The GRFs vary over time during stance. This study was aimed to investigate the variances of GRFs in rearfoot striking runners across incremental speeds. Thirty female and male runners joined the running tests on the instrumented treadmill with speeds of 2.7, 3.0, 3.3, and 3.7 m/s. The discrete parameters of vertical average loading rate in the current study are consistent with the literature findings. The principal component analysis was modeled to investigate the main variances (95%) in the GRFs over stance. The females varied in the magnitude of braking and propulsive forces (PC1, 84.93%), whereas the male runners varied in the timing of propulsion (PC1, 53.38%). The female runners dominantly varied in the transient between the first and second peaks of vertical GRF (PC1, 36.52%) and LR (PC2, 33.76%), whereas the males variated in the LR and second peak of vertical GRF (PC1, 78.69%). Knowledge reported in the current study suggested the difference of the magnitude and patterns of GRF between male and female runners across different speeds. These findings may have implications for the prevention of sex-specific running-related injuries and could be integrated with wearable signals for the in-field prediction and estimation of impact loadings and GRFs.

The Effects of Cycling on Running Mechanics

1996 ◽  
Vol 12 (4) ◽  
pp. 470-479 ◽  
Author(s):  
Edward J. Quigley ◽  
James G. Richards
Keyword(s):  
High Speed ◽  
Reaction Force ◽  
Vertical Displacement ◽  
Ankle Joints ◽  
Angular Velocities ◽  
Reaction Forces ◽  
Stance Time ◽  
Left And Right ◽  
Force Data ◽  
Running Mechanics

This study investigated the mechanical effects that cycling has on running style which may explain the discomfort associated with the transition from cycling to running. The joint angles, angular velocities, reaction forces, and reaction moments of the left and right hip, knee, and ankle joints as well as stance time, flight time, stride length, and maximum vertical displacement of the center of gravity were measured using high-speed video and ground reaction force data. Data were collected from 11 competitive biathletes and triathletes. Each subject's running mechanics were determined from 10 trials for each of three conditions: (a) unfatigued, (b) immediately following 30 min of running, and (c) immediately following 30 min of bicycling. The results indicate that a person's running mechanics, as described by the variables above, are virtually unchanged between each of the three conditions. Therefore, awkwardness of the bicycle-to-run transition may not be related to a change in running mechanics.

Abstract WP105: A Practical Wake up Tpa Protocol at a United States Based Comprehensive Stroke Center Hub and Its Telestroke Spokes

Stroke ◽  
2020 ◽  
Vol 51 (Suppl_1) ◽  
Author(s):  
Navdeep S Sangha ◽  
Duy Le ◽  
Raeesa Dhanji ◽  
Denise Gaffney ◽  
David McCartney ◽  
...  
Keyword(s):  
United States ◽  
Small Sample Size ◽  
Statistical Significance ◽  
The United States ◽  
Small Sample ◽  
The Difference ◽  
Waking Up ◽  
Comprehensive Stroke Center ◽  
Stroke Center ◽  
Main Barrier

Background: IV tPA is established as an effective treatment for acute ischemic stroke. Currently it is endorsed up to 4.5 hours of last known well time by major guidelines. A randomized trial, WAKE-UP, displayed its safety and efficacy in patients who presented within 4.5 hours of waking up with their symptoms. Objective: To establish a practical tPA protocol for patients who wake up or are found with stroke symptoms at a large Comprehensive Stroke Center (CSC) and its 13 telestroke spokes (TS) based on the WAKE-UP trial. Methods: A wake up tPA protocol was created and given to all teleneurologists. Door to needle times (DTN) and reasons for no tPA were collected for 12 months post implementation and evaluated for differences between wake up (WU) and non-wake up (NW) patients. Results: 93 WU patients were identified; 23 at CSC and 70 at TS. 11 (47.8%) vs. 4 (5.7%) patients received tPA at CSC and TS, respectively. Median DTN was not significantly different for WU patients at CSC vs. TS (64 vs. 89 mins, p=0.54). Median DTN at CSC was shorter for NW vs. WU (37 vs. 64 mins; p=0.003). Similarly, median DTN at TS trended toward being shorter for NW vs. WU (44 vs. 89 mins; p=0.062). The reasons for no tPA at CSC were no mismatch found in 6 (50%), and MRI unavailability in 6 (50%); at TS were no mismatch found in 11 (16.6%), MRI unavailability in 54 (81,1%) and MRI was contraindicated in 1 (1.5%). Conclusion: Treating WU patients using a CSC Hub and TS model is feasible. DTN are longer for WU vs. NW. In the United States, MRI availability is the main barrier to WU tPA at both CSC and community hospitals. The difference between median DTN for WU between CSC and TS did not reach statistical significance, likely due to the small sample size.

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.

Effects of trial repetition, limb side, intraday and inter-week variation on vertical and craniocaudal ground reaction forces in clinically normal Labrador Retrievers

2011 ◽  
Vol 24 (06) ◽  
pp. 435-444 ◽  
Author(s):  
B. Nordquist ◽  
J. Fischer ◽  
S. Y. Kim ◽  
S. M. Stover ◽  
T. Garcia-Nolen ◽  
...  
Keyword(s):  
Data Collection ◽  
Ground Reaction Force ◽  
Reaction Force ◽  
Ground Reaction Forces ◽  
Vertical Ground Reaction Force ◽  
Reaction Forces ◽  
Pelvic Limb ◽  
Vertical Ground ◽  
Labrador Retrievers ◽  
Force Data

SummaryObjectives: To document the contributions of trial repetition, limb side, and intraday and inter-week measurements on variation in vertical and craniocaudal ground reaction force data.Methods: Following habituation, force and time data were collected for all four limbs of seven Labrador Retrievers during sets of five valid trot trials. Each set was performed twice daily (morning and afternoon), every seven days for three consecutive weeks. A repeated measures analysis of variance was used to determine the effects of limb, trial, intraday, and inter-week factors on ground reaction force data for the thoracic and pelvic limbs.Results: Of the four factors evaluated, variation due to trial repetition had the largest magnitude of effect on ground reaction forces. Trial within a set of data had an effect on all craniocaudal, but not vertical, ground reaction force variables studied, for the thoracic limbs. The first of five trials was often different from later trials. Some thoracic limb and pelvic limb variables were different between weeks. A limb side difference was only apparent for pelvic limb vertical ground reaction force data. Only pelvic limb craniocaudal braking variables were different between sets within a day.Discussion and clinical significance: When controlling for speed, handler, gait, weight and dog breed, variation in ground reaction forces mainly arise from trial repetition and inter-week data collection. When using vertical peak force and impulse to evaluate treatment, trial repetition and inter-week data collection should have minimal effect of the data.

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.

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