scholarly journals The scaling of ground reaction forces and duty factor in monitor lizards: implications for locomotion in sprawling tetrapods

2021 ◽  
Vol 17 (2) ◽  
pp. 20200612 ◽  
Author(s):  
Robert L. Cieri ◽  
Taylor J. M. Dick ◽  
Robert Irwin ◽  
Daniel Rumsey ◽  
Christofer J. Clemente
Keyword(s):  
Body Size ◽  
Duty Factor ◽  
Ground Reaction Forces ◽  
Cross Sectional ◽  
Terrestrial Locomotion ◽  
Reaction Forces ◽  
Generation Capacity ◽  
Monitor Lizards ◽  
Force Time ◽  
Muscle Cross Sectional Area

Geometric scaling predicts a major challenge for legged, terrestrial locomotion. Locomotor support requirements scale identically with body mass ( α M 1 ), while force-generation capacity should scale α M 2/3 as it depends on muscle cross-sectional area. Mammals compensate with more upright limb postures at larger sizes, but it remains unknown how sprawling tetrapods deal with this challenge. Varanid lizards are an ideal group to address this question because they cover an enormous body size range while maintaining a similar bent-limb posture and body proportions. This study reports the scaling of ground reaction forces and duty factor for varanid lizards ranging from 7 g to 37 kg. Impulses (force×time) ( α M 0.99−1.34 ) and peak forces ( α M 0.73−1.00 ) scaled higher than expected. Duty factor scaled α M 0.04 and was higher for the hindlimb than the forelimb. The proportion of vertical impulse to total impulse increased with body size, and impulses decreased while peak forces increased with speed.

scholarly journals Running ground reaction forces across footwear conditions are predicted from the motion of two body mass components

2019 ◽  
Vol 126 (5) ◽  
pp. 1315-1325 ◽  
Author(s):  
Andrew B. Udofa ◽  
Kenneth P. Clark ◽  
Laurence J. Ryan ◽  
Peter G. Weyand
Keyword(s):  
Ground Reaction Force ◽  
Lower Limb ◽  
Reaction Force ◽  
Ground Reaction Forces ◽  
Vertical Ground Reaction Force ◽  
Time Patterns ◽  
Foot Strike ◽  
Reaction Forces ◽  
Vertical Ground ◽  
Force Time

Although running shoes alter foot-ground reaction forces, particularly during impact, how they do so is incompletely understood. Here, we hypothesized that footwear effects on running ground reaction force-time patterns can be accurately predicted from the motion of two components of the body’s mass (mb): the contacting lower-limb (m1 = 0.08mb) and the remainder (m2 = 0.92mb). Simultaneous motion and vertical ground reaction force-time data were acquired at 1,000 Hz from eight uninstructed subjects running on a force-instrumented treadmill at 4.0 and 7.0 m/s under four footwear conditions: barefoot, minimal sole, thin sole, and thick sole. Vertical ground reaction force-time patterns were generated from the two-mass model using body mass and footfall-specific measures of contact time, aerial time, and lower-limb impact deceleration. Model force-time patterns generated using the empirical inputs acquired for each footfall matched the measured patterns closely across the four footwear conditions at both protocol speeds ( r2 = 0.96 ± 0.004; root mean squared error  = 0.17 ± 0.01 body-weight units; n = 275 total footfalls). Foot landing angles (θF) were inversely related to footwear thickness; more positive or plantar-flexed landing angles coincided with longer-impact durations and force-time patterns lacking distinct rising-edge force peaks. Our results support three conclusions: 1) running ground reaction force-time patterns across footwear conditions can be accurately predicted using our two-mass, two-impulse model, 2) impact forces, regardless of foot strike mechanics, can be accurately quantified from lower-limb motion and a fixed anatomical mass (0.08mb), and 3) runners maintain similar loading rates (ΔFvertical/Δtime) across footwear conditions by altering foot strike angle to regulate the duration of impact. NEW & NOTEWORTHY Here, we validate a two-mass, two-impulse model of running vertical ground reaction forces across four footwear thickness conditions (barefoot, minimal, thin, thick). Our model allows the impact portion of the impulse to be extracted from measured total ground reaction force-time patterns using motion data from the ankle. The gait adjustments observed across footwear conditions revealed that runners maintained similar loading rates across footwear conditions by altering foot strike angles to regulate the duration of impact.

Twisting and Bending: The Functional Role of Salamander Lateral Hypaxial Musculature During Locomotion

2001 ◽  
Vol 204 (11) ◽  
pp. 1979-1989 ◽  
Author(s):  
Wallace O. Bennett ◽  
Rachel S. Simons ◽  
Elizabeth L. Brainerd
Keyword(s):  
High Intensity ◽  
High Speed ◽  
The Body ◽  
Transversus Abdominis ◽  
Fine Motor ◽  
Emg Activity ◽  
Ground Reaction Forces ◽  
Terrestrial Locomotion ◽  
Reaction Forces ◽  
Hypaxial Muscle

SUMMARY The function of the lateral hypaxial muscles during locomotion in tetrapods is controversial. Currently, there are two hypotheses of lateral hypaxial muscle function. The first, supported by electromyographic (EMG) data from a lizard (Iguana iguana) and a salamander (Dicamptodon ensatus), suggests that hypaxial muscles function to bend the body during swimming and to resist long-axis torsion during walking. The second, supported by EMG data from lizards during relatively high-speed locomotion, suggests that these muscles function primarily to bend the body during locomotion, not to resist torsional forces. To determine whether the results from D. ensatus hold for another salamander, we recorded lateral hypaxial muscle EMGs synchronized with body and limb kinematics in the tiger salamander Ambystoma tigrinum. In agreement with results from aquatic locomotion in D. ensatus, all four layers of lateral hypaxial musculature were found to show synchronous EMG activity during swimming in A. tigrinum. Our findings for terrestrial locomotion also agree with previous results from D. ensatus and support the torsion resistance hypothesis for terrestrial locomotion. We observed asynchronous EMG bursts of relatively high intensity in the lateral and medial pairs of hypaxial muscles during walking in tiger salamanders (we call these ‘α-bursts’). We infer from this pattern that the more lateral two layers of oblique hypaxial musculature, Mm. obliquus externus superficialis (OES) and obliquus externus profundus (OEP), are active on the side towards which the trunk is bending, while the more medial two layers, Mm. obliquus internus (OI) and transversus abdominis (TA), are active on the opposite side. This result is consistent with the hypothesis proposed for D. ensatus that the OES and OEP generate torsional moments to counteract ground reaction forces generated by forelimb support, while the OI and TA generate torsional moments to counteract ground reaction forces from hindlimb support. However, unlike the EMG pattern reported for D. ensatus, a second, lower-intensity burst of EMG activity (‘β-burst’) was sometimes recorded from the lateral hypaxial muscles in A. tigrinum. As seen in other muscle systems, these β-bursts of hypaxial muscle coactivation may function to provide fine motor control during locomotion. The presence of asynchronous, relatively high-intensity α-bursts indicates that the lateral hypaxial muscles generate torsional moments during terrestrial locomotion, but it is possible that the balance of forces from both α- and β-bursts may allow the lateral hypaxial muscles to contribute to lateral bending of the body as well.

Acceleration and balance in trotting dogs

1999 ◽  
Vol 202 (24) ◽  
pp. 3565-3573 ◽  
Author(s):  
D.V. Lee ◽  
J.E. Bertram ◽  
R.J. Todhunter
Keyword(s):  
Body Weight ◽  
Steady State ◽  
The Body ◽  
Ground Reaction Forces ◽  
Pitching Moment ◽  
Acceleration And Deceleration ◽  
Reaction Forces ◽  
Force Time

During quadrupedal trotting, diagonal pairs of limbs are set down in unison and exert forces on the ground simultaneously. Ground-reaction forces on individual limbs of trotting dogs were measured separately using a series of four force platforms. Vertical and fore-aft impulses were determined for each limb from the force/time recordings. When mean fore-aft acceleration of the body was zero in a given trotting step (steady state), the fraction of vertical impulse on the forelimb was equal to the fraction of body weight supported by the forelimbs during standing (approximately 60 %). When dogs accelerated or decelerated during a trotting step, the vertical impulse was redistributed to the hindlimb or forelimb, respectively. This redistribution of the vertical impulse is due to a moment exerted about the pitch axis of the body by fore-aft accelerating and decelerating forces. Vertical forces exerted by the forelimb and hindlimb resist this pitching moment, providing stability during fore-aft acceleration and deceleration.

Effect of Different Synthetic Sport Surfaces on Ground Reaction Forces at Landing in Netball

1988 ◽  
Vol 4 (2) ◽  
pp. 130-145 ◽  
Author(s):  
Julie R. Steele ◽  
Peter D. Milburn
Keyword(s):  
A Priori ◽  
Reaction Force ◽  
Movement Pattern ◽  
Ground Reaction Forces ◽  
Maximum Peak ◽  
Time To Peak ◽  
Time Histories ◽  
Reaction Forces ◽  
Force Time ◽  
Initial Peak

This study examined the influence of 12 different synthetic sport surfaces (bitumen, concrete, 3 samples of synthetic grass, and 7 samples of rubber surfaces) on ground reaction forces at landing in netball. Ground reaction force data were obtained for 10 skilled netball players at landing after performing a typical attacking netball movement pattern. Force–time histories of the maximum peak vertical ground reaction forces (VGRF), the initial peak VGRF, and peak braking forces were determined for each trial. Results of the a priori planned comparison analysis indicated that subjects demonstrated significantly longer time to maximum peak VGRF and initial peak VGRF when landing on grass, higher peak braking forces when landing on bitumen and concrete combined, and a significantly shorter time to peak braking force when landing on grass in comparison to other samples tested. It was concluded that the rubber surfaces tested demonstrated the potential for being the most suitable playing surface for minimization of injuries in netball.

Relationships of Body Weight, Body Size, Subject Velocity, and Vertical Ground Reaction Forces in Trotting Dogs

2010 ◽  
Vol 39 (7) ◽  
pp. 863-869 ◽  
Author(s):  
Katja Voss ◽  
Luca Galeandro ◽  
Thomas Wiestner ◽  
Michael Haessig ◽  
Pierre M. Montavon
Keyword(s):  
Body Weight ◽  
Body Size ◽  
Ground Reaction Forces ◽  
Reaction Forces ◽  
Vertical Ground ◽  
Vertical Ground Reaction Forces

scholarly journals The Effect of Diabetic Peripheral Neuropathy on Ground Reaction Forces during Straight Walking in Stroke Survivors

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Amirah Mustapa ◽  
Maria Justine ◽  
Nadia Mohd Mustafah ◽  
Haidzir Manaf
Keyword(s):  
Peripheral Neuropathy ◽  
Diabetic Peripheral Neuropathy ◽  
Stroke Survivors ◽  
Ground Reaction Forces ◽  
Healthy Controls ◽  
Cross Sectional ◽  
Lateral Forces ◽  
Reaction Forces ◽  
The Impact ◽  
Anterior Posterior

Purpose. The aim of this present study was to investigate the ground reaction forces (GRFs) alterations in stroke survivors with diabetic peripheral neuropathy (DPN).Methods. Ten stroke survivors with DPN, 10 stroke survivors without DPN, and 10 healthy controls with matched body weight between groups participated in this case-control cross-sectional study. Three-dimensional GRFs (anterior-posterior, medial-lateral, and vertical) were collected at a comfortable walking speed using the Nexus Vicon motion analysis system and force plate. The Kruskal–Wallis test was used to analyze GRFs parameters.Results. We found significant alterations of medial-lateral forces of the nonparetic side and vertical forces of the paretic side in stroke survivors with DPN compared to stroke survivors without DPN and healthy controls. In addition, there were smaller braking and lower propulsion peak in anterior-posterior forces, smaller magnitude of medial-lateral forces, and lower first and second peak of vertical forces in stroke survivors with DPN compared to stroke survivors without DPN and healthy controls.Conclusion. The study findings identified that GRFs were affected in stroke survivors with DPN on both the paretic and the nonparetic sides. Further investigations are warranted to explore the impact of DPN on the kinematics and muscle activity related to the gait performance in stroke survivors with DPN.

Effect of dog breed and body conformation on vertical ground reaction forces, impulses, and stance times

2011 ◽  
Vol 24 (02) ◽  
pp. 106-112 ◽  
Author(s):  
T. Wiestner ◽  
L. Galeandro ◽  
M. Hässig ◽  
P. M. Montavon ◽  
K. Voss
Keyword(s):  
Body Weight ◽  
Body Size ◽  
Force Plate ◽  
Ground Reaction Forces ◽  
Gait Parameters ◽  
Reaction Forces ◽  
Vertical Ground ◽  
Dog Breed ◽  
Similar Body ◽  
Vertical Ground Reaction Forces

Summary Objectives: To assess whether fully normalised vertical ground reaction forces and stance times obtained at a trot depend on dog breed or body conformations. Methods: Peak vertical forces (PVF), vertical impulses (VI), stance times (ST), and ratio of forelimb impulse to total impulse (RVI) of 54 dogs of seven different breeds were normalised to body weight and body size according to the theory of dynamic similarity, and were tested for differences between breeds. Breeds were Borzoi, Bernese Mountain dog, Great Dane, Labrador Retriever, Landseer, Rhode-sian Ridgeback, and Rottweiler. Body length ratio (BLR) and body mass index (BMI) were also compared between breeds. Results: Significant differences between breeds were found for the normalised fore-limb PVF, VI and ST, and hindlimb PVF. Looking at individual breeds, it was most evident that Borzois had a lower forelimb VI, and a higher hindlimb PVF than the other breeds. This resulted in Borzois having a lower RVI compared to other dogs, indicating a more caudally located centre of gravity. Only a few differences in gait parameters were found between other dog breeds. The BMI was significantly lower in Borzois than in other breeds, but was otherwise not associated with gait parameters. Clinical significance: Force plate data of dogs of different breeds are not necessarily comparable, even after full normalisation to body weight and body size. Group comparisons should only be made when the groups consist of breeds with similar body conformations.

scholarly journals Analysis of ground reaction forces in the second and third trimesters of pregnancy during walking

Kinesiology ◽  
2019 ◽  
Vol 51 (2) ◽  
pp. 198-205
Author(s):  
Abeer Mohammed EL Deeb ◽  
Amr Almaz Abdel-Aziem
Keyword(s):  
Pregnant Women ◽  
Cross Sectional Study ◽  
Ground Reaction Forces ◽  
Cross Sectional ◽  
Propulsion Force ◽  
Reaction Forces ◽  
Time Parameters ◽  
The Difference ◽  
Analysis System ◽  
Second Peak

The objective of the current study was to examine the effect of pregnancy during the 2nd and 3rd trimesters on ground reaction forces (GRFs). Twenty-four non-pregnant women and forty-eight pregnant women in the second and third trimesters participated in this cross-sectional study. Qualisys Gait Analysis System was used to analyze peaks and time parameters of GRFs in vertical (Fz), antero-posterior (Fx) and medio-lateral directions (Fy). The results showed that there were no significant differences between the non-pregnant and the pregnant women in the first peak (Fz1) (p=.147) and the second peak (Fz2) (p=.125) of vertical GRF, braking force (FyB) (p=.867) and propulsion force (FyP) (p=.929), as well as lateral (FxL) (p=0.994) and medial (FxM) GRF (p=.920). However, there was a significant increase in the Fz minimum (min) (p=.008), and a decrease in the difference between the Fz1 and Fz min (p=.042) and the difference between Fz2 and Fz min (p=.028). Moreover, there were increases in the time taken to reach the Fz1 (p=.024), Fz2 (p=.005), Fz min (=0.001), FyB (p=.010), FyP (p=.001), FxL (p=.010) and FxM (p=.011). These findings displayed that the pregnant women assumed a flatter pattern of vertical GRF and a decreased downward movement of center of gravity. This pattern may help to make the gait smooth and efficient. Increased time to reach peaks of GRFs may be a strategy to maximize balance during pregnancy.

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