Sex and stride length impact leg stiffness and ground reaction forces when running with body borne load

2019 ◽  
Vol 86 ◽  
pp. 96-101 ◽  
Author(s):  
Nicholas J. Lobb ◽  
AuraLea C. Fain ◽  
Kayla D. Seymore ◽  
Tyler N. Brown
Keyword(s):  
Stride Length ◽  
Ground Reaction Forces ◽  
Leg Stiffness ◽  
Reaction Forces

Reduced prosthetic stiffness lowers the metabolic cost of running for athletes with bilateral transtibial amputations

2017 ◽  
Vol 122 (4) ◽  
pp. 976-984 ◽  
Author(s):  
Owen N. Beck ◽  
Paolo Taboga ◽  
Alena M. Grabowski
Keyword(s):  
Lower Limb ◽  
Metabolic Cost ◽  
Ground Reaction Forces ◽  
Metabolic Rates ◽  
Distance Running ◽  
Cost Of Transport ◽  
Leg Stiffness ◽  
Metabolic Costs ◽  
In Series ◽  
Reaction Forces

Inspired by the springlike action of biological legs, running-specific prostheses are designed to enable athletes with lower-limb amputations to run. However, manufacturer’s recommendations for prosthetic stiffness and height may not optimize running performance. Therefore, we investigated the effects of using different prosthetic configurations on the metabolic cost and biomechanics of running. Five athletes with bilateral transtibial amputations each performed 15 trials on a force-measuring treadmill at 2.5 or 3.0 m/s. Athletes ran using each of 3 different prosthetic models (Freedom Innovations Catapult FX6, Össur Flex-Run, and Ottobock 1E90 Sprinter) with 5 combinations of stiffness categories (manufacturer’s recommended and ± 1) and heights (International Paralympic Committee’s maximum competition height and ± 2 cm) while we measured metabolic rates and ground reaction forces. Overall, prosthetic stiffness [fixed effect (β) = 0.036; P = 0.008] but not height ( P ≥ 0.089) affected the net metabolic cost of transport; less stiff prostheses reduced metabolic cost. While controlling for prosthetic stiffness (in kilonewtons per meter), using the Flex-Run (β = −0.139; P = 0.044) and 1E90 Sprinter prostheses (β = −0.176; P = 0.009) reduced net metabolic costs by 4.3–4.9% compared with using the Catapult prostheses. The metabolic cost of running improved when athletes used prosthetic configurations that decreased peak horizontal braking ground reaction forces (β = 2.786; P = 0.001), stride frequencies (β = 0.911; P < 0.001), and leg stiffness values (β = 0.053; P = 0.009). Remarkably, athletes did not maintain overall leg stiffness across prosthetic stiffness conditions. Rather, the in-series prosthetic stiffness governed overall leg stiffness. The metabolic cost of running in athletes with bilateral transtibial amputations is influenced by prosthetic model and stiffness but not height. NEW & NOTEWORTHY We measured the metabolic rates and biomechanics of five athletes with bilateral transtibial amputations while running with different prosthetic configurations. The metabolic cost of running for these athletes is minimized by using an optimal prosthetic model and reducing prosthetic stiffness. The metabolic cost of running was independent of prosthetic height, suggesting that longer legs are not advantageous for distance running. Moreover, the in-series prosthetic stiffness governs the leg stiffness of athletes with bilateral leg amputations.

An Instrument That Simultaneously Measures Spatiotemporal Gait Parameters and Ground Reaction Forces of Locomoting Rats

2008 ◽  
Author(s):  
U. Tasch ◽  
P. Moubarak ◽  
W. Tang ◽  
L. Zhu ◽  
R. M. Lovering ◽  
...  
Keyword(s):  
Stride Length ◽  
Vertical Direction ◽  
Ground Reaction Forces ◽  
Gait Parameters ◽  
Load Cells ◽  
Floor Vibrations ◽  
Reaction Forces ◽  
Models Of Injury ◽  
Vertical Ground

We describe an instrument that assesses two features of the gait of rats, spatiotemporal paw movement variables (SPMV) and ground reaction forces (GRF) in the vertical direction. The GRF and the SPMV variables are measured electrically by eight single axis load-cells that support two floor plates. We can derive four gait parameters from the SPMV and GRF measured by the instrument: the stride length of individual limbs, the maximum and mean vertical ground forces, and the intensity of the vibrations created by each paw during locomotion. Measurements of the vertical GRF show errors of less than 3.5%; errors in the determination of the paw positions, used to derive stride lengths, are less than 9 mm. Here we report the stride length, maximum and mean GRF values, and the intensity of the floor vibrations of healthy adult mature rats. Our instrument is capable of evaluating changes in these gait parameters in rat models of injury and disease.

scholarly journals Spring-like leg behaviour, musculoskeletal mechanics and control in maximum and submaximum height human hopping

2011 ◽  
Vol 366 (1570) ◽  
pp. 1516-1529 ◽  
Author(s):  
Maarten F. Bobbert ◽  
L. J. Richard Casius
Keyword(s):  
Energy Expenditure ◽  
Muscle Activation ◽  
Mechanical Energy ◽  
Reaction Force ◽  
Ground Reaction Forces ◽  
Centre Of Mass ◽  
Leg Stiffness ◽  
Reaction Forces ◽  
And Control ◽  
The Relationship

The purpose of this study was to understand how humans regulate their ‘leg stiffness’ in hopping, and to determine whether this regulation is intended to minimize energy expenditure. ‘Leg stiffness’ is the slope of the relationship between ground reaction force and displacement of the centre of mass (CM). Variations in leg stiffness were achieved in six subjects by having them hop at maximum and submaximum heights at a frequency of 1.7 Hz. Kinematics, ground reaction forces and electromyograms were measured. Leg stiffness decreased with hopping height, from 350 N m −1 kg −1 at 26 cm to 150 N m −1 kg −1 at 14 cm. Subjects reduced hopping height primarily by reducing the amplitude of muscle activation. Experimental results were reproduced with a model of the musculoskeletal system comprising four body segments and nine Hill-type muscles, with muscle stimulation STIM( t ) as only input. Correspondence between simulated hops and experimental hops was poor when STIM( t ) was optimized to minimize mechanical energy expenditure, but good when an objective function was used that penalized jerk of CM motion, suggesting that hopping subjects are not minimizing energy expenditure. Instead, we speculated, subjects are using a simple control strategy that results in smooth movements and a decrease in leg stiffness with hopping height.

scholarly journals Gait Disturbances in Dystrophic Hamsters

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Thomas G. Hampton ◽  
Ajit Kale ◽  
Ivo Amende ◽  
Wenlong Tang ◽  
Scott McCue ◽  
...  
Keyword(s):  
Animal Model ◽  
Muscular Dystrophy ◽  
Stride Length ◽  
Ground Reaction Forces ◽  
Functional Aspects ◽  
Reaction Forces ◽  
Gait Abnormalities ◽  
Gait Disturbances ◽  
Quantitative Gait Analysis ◽  
Treadmill Belt

The delta-sarcoglycan-deficient hamster is an excellent model to study muscular dystrophy. Gait disturbances, important clinically, have not been described in this animal model. We applied ventral plane videography (DigiGait) to analyze gait in BIO TO-2 dystrophic and BIO F1B control hamsters walking on a transparent treadmill belt. Stride length was~13% shorter () in TO-2 hamsters at 9 months of age compared to F1B hamsters. Hindlimb propulsion duration, an indicator of muscle strength, was shorter in 9-month-old TO-2 ( ms) compared to F1B hamsters ( ms; ). Braking duration, reflecting generation of ground reaction forces, was delayed in 9-month-old TO-2 ( ms) compared to F1B hamsters ( ms; ). Hindpaw eversion, evidence of muscle weakness, was greater in 9-month-old TO-2 than in F1B hamsters ( versus ; ). Incline and decline walking aggravated gait disturbances in TO-2 hamsters at 3 months of age. Several gait deficits were apparent in TO-2 hamsters at 1 month of age. Quantitative gait analysis demonstrates that dystrophic TO-2 hamsters recapitulate functional aspects of human muscular dystrophy. Early detection of gait abnormalities in a convenient animal model may accelerate the development of therapies for muscular dystrophy.

scholarly journals How do prosthetic stiffness, height and running speed affect the biomechanics of athletes with bilateral transtibial amputations?

2017 ◽  
Vol 14 (131) ◽  
pp. 20170230 ◽  
Author(s):  
Owen N. Beck ◽  
Paolo Taboga ◽  
Alena M. Grabowski
Keyword(s):  
Treadmill Running ◽  
Ground Reaction Forces ◽  
Ground Contact ◽  
Step Frequency ◽  
Running Speed ◽  
Leg Stiffness ◽  
Reaction Forces ◽  
Ground Contact Time ◽  
Available Information ◽  
Distance Running Performance

Limited available information describes how running-specific prostheses and running speed affect the biomechanics of athletes with bilateral transtibial amputations. Accordingly, we quantified the effects of prosthetic stiffness, height and speed on the biomechanics of five athletes with bilateral transtibial amputations during treadmill running. Each athlete performed a set of running trials with 15 different prosthetic model, stiffness and height combinations. Each set of trials began with the athlete running on a force-measuring treadmill at 3 m s −1 , subsequent trials incremented by 1 m s −1 until they achieved their fastest attainable speed. We collected ground reaction forces (GRFs) during each trial. Prosthetic stiffness, height and running speed each affected biomechanics. Specifically, with stiffer prostheses, athletes exhibited greater peak and stance average vertical GRFs ( β = 0.03; p < 0.001), increased overall leg stiffness ( β = 0.21; p < 0.001), decreased ground contact time ( β = −0.07; p < 0.001) and increased step frequency ( β = 0.042; p < 0.001). Prosthetic height inversely associated with step frequency ( β = −0.021; p < 0.001). Running speed inversely associated with leg stiffness ( β = −0.58; p < 0.001). Moreover, at faster running speeds, the effect of prosthetic stiffness and height on biomechanics was mitigated and unchanged, respectively. Thus, prosthetic stiffness, but not height, likely influences distance running performance more than sprinting performance for athletes with bilateral transtibial amputations.

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.

Effects of head and tail as swinging appendages on the dynamic walking performance of a quadruped robot

Robotica ◽  
2016 ◽  
Vol 34 (12) ◽  
pp. 2878-2891 ◽  
Author(s):  
Xiuli Zhang ◽  
Jiaqing Gong ◽  
Yanan Yao
Keyword(s):  
Stride Length ◽  
Pattern Generator ◽  
Flight Time ◽  
Quadruped Robot ◽  
Ground Reaction Forces ◽  
Reaction Forces ◽  
Fixed Phase ◽  
Walking Performance ◽  
Hopf Oscillator ◽  
Phase Differences

SUMMARYWe designed a quadruped robot with a one-degree-of-freedom (1-DOF)-pitch head, a 1-DOF-roll tail, and 14 active DOFs in total, which are controlled via a central pattern generator (CPG) based on a Hopf oscillator. Head and tail movements are coupled to the leg movements with fixed phase differences. Experiments show that tail swinging in roll can equilibrate feet–ground reaction forces (GRF), reducing yaw errors and enabling the robot to maintain its direction when trotting. Head swing in pitch has the potential to increase flight time and stride length of the swinging legs and increase the robot's forward velocity when running in bounds.

scholarly journals Prosthetic model, but not stiffness or height, affects the metabolic cost of running for athletes with unilateral transtibial amputations

2017 ◽  
Vol 123 (1) ◽  
pp. 38-48 ◽  
Author(s):  
Owen N. Beck ◽  
Paolo Taboga ◽  
Alena M. Grabowski
Keyword(s):  
Lower Limb ◽  
Metabolic Cost ◽  
Ground Reaction Forces ◽  
Ground Contact ◽  
Limb Stiffness ◽  
Leg Stiffness ◽  
In Series ◽  
Reaction Forces ◽  
Vertical Ground ◽  
Vertical Ground Reaction Forces

Running-specific prostheses enable athletes with lower limb amputations to run by emulating the spring-like function of biological legs. Current prosthetic stiffness and height recommendations aim to mitigate kinematic asymmetries for athletes with unilateral transtibial amputations. However, it is unclear how different prosthetic configurations influence the biomechanics and metabolic cost of running. Consequently, we investigated how prosthetic model, stiffness, and height affect the biomechanics and metabolic cost of running. Ten athletes with unilateral transtibial amputations each performed 15 running trials at 2.5 or 3.0 m/s while we measured ground reaction forces and metabolic rates. Athletes ran using three different prosthetic models with five different stiffness category and height combinations per model. Use of an Ottobock 1E90 Sprinter prosthesis reduced metabolic cost by 4.3 and 3.4% compared with use of Freedom Innovations Catapult [fixed effect (β) = −0.177; P < 0.001] and Össur Flex-Run (β = −0.139; P = 0.002) prostheses, respectively. Neither prosthetic stiffness ( P ≥ 0.180) nor height ( P = 0.062) affected the metabolic cost of running. The metabolic cost of running was related to lower peak (β = 0.649; P = 0.001) and stance average (β = 0.772; P = 0.018) vertical ground reaction forces, prolonged ground contact times (β = −4.349; P = 0.012), and decreased leg stiffness (β = 0.071; P < 0.001) averaged from both legs. Metabolic cost was reduced with more symmetric peak vertical ground reaction forces (β = 0.007; P = 0.003) but was unrelated to stride kinematic symmetry ( P ≥ 0.636). Therefore, prosthetic recommendations based on symmetric stride kinematics do not necessarily minimize the metabolic cost of running. Instead, an optimal prosthetic model, which improves overall biomechanics, minimizes the metabolic cost of running for athletes with unilateral transtibial amputations.NEW & NOTEWORTHY The metabolic cost of running for athletes with unilateral transtibial amputations depends on prosthetic model and is associated with lower peak and stance average vertical ground reaction forces, longer contact times, and reduced leg stiffness. Metabolic cost is unrelated to prosthetic stiffness, height, and stride kinematic symmetry. Unlike nonamputees who decrease leg stiffness with increased in-series surface stiffness, biological limb stiffness for athletes with unilateral transtibial amputations is positively correlated with increased in-series (prosthetic) stiffness.

scholarly journals Stability in skipping gaits

2016 ◽  
Vol 3 (11) ◽  
pp. 160602 ◽  
Author(s):  
Emanuel Andrada ◽  
Roy Müller ◽  
Reinhard Blickhan
Keyword(s):  
Numerical Simulations ◽  
Inverted Pendulum ◽  
Ground Reaction Forces ◽  
Fast Running ◽  
Leg Stiffness ◽  
Adult Humans ◽  
Speed Range ◽  
Reaction Forces ◽  
System Energy ◽  
Male Subjects

As an alternative to walking and running, humans are able to skip. However, adult humans avoid it. This fact seems to be related to the higher energetic costs associated with skipping. Still, children, some birds, lemurs and lizards use skipping gaits during daily locomotion. We combined experimental data on humans with numerical simulations to test whether stability and robustness motivate this choice. Parameters for modelling were obtained from 10 male subjects. They locomoted using unilateral skipping along a 12 m runway. We used a bipedal spring loaded inverted pendulum to model and to describe the dynamics of skipping. The subjects displayed higher peak ground reaction forces and leg stiffness in the first landing leg (trailing leg) compared to the second landing leg (leading leg). In numerical simulations, we found that skipping is stable across an amazing speed range from skipping on the spot to fast running speeds. Higher leg stiffness in the trailing leg permits longer strides at same system energy. However, this strategy is at the same time less robust to sudden drop perturbations than skipping with a stiffer leading leg. A slightly higher stiffness in the leading leg is most robust, but might be costlier.

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