Energetics and mechanics of human running on surfaces of different stiffnesses

2002 ◽  
Vol 92 (2) ◽  
pp. 469-478 ◽  
Author(s):  
Amy E. Kerdok ◽  
Andrew A. Biewener ◽  
Thomas A. McMahon ◽  
Peter G. Weyand ◽  
Hugh M. Herr
Keyword(s):  
Reaction Force ◽  
Force Plate ◽  
Metabolic Cost ◽  
Running Economy ◽  
Leg Length ◽  
Kinematic Data ◽  
Surface Stiffness ◽  
Leg Stiffness ◽  
Compliant Surfaces ◽  
Male Subjects

Mammals use the elastic components in their legs (principally tendons, ligaments, and muscles) to run economically, while maintaining consistent support mechanics across various surfaces. To examine how leg stiffness and metabolic cost are affected by changes in substrate stiffness, we built experimental platforms with adjustable stiffness to fit on a force-plate-fitted treadmill. Eight male subjects [mean body mass: 74.4 ± 7.1 (SD) kg; leg length: 0.96 ± 0.05 m] ran at 3.7 m/s over five different surface stiffnesses (75.4, 97.5, 216.8, 454.2, and 945.7 kN/m). Metabolic, ground-reaction force, and kinematic data were collected. The 12.5-fold decrease in surface stiffness resulted in a 12% decrease in the runner's metabolic rate and a 29% increase in their leg stiffness. The runner's support mechanics remained essentially unchanged. These results indicate that surface stiffness affects running economy without affecting running support mechanics. We postulate that an increased energy rebound from the compliant surfaces studied contributes to the enhanced running economy.

A Comparison of Computation Methods for Leg Stiffness During Hopping

2014 ◽  
Vol 30 (1) ◽  
pp. 154-159 ◽  
Author(s):  
Hiroaki Hobara ◽  
Koh Inoue ◽  
Yoshiyuki Kobayashi ◽  
Toru Ogata
Keyword(s):  
Ground Reaction Force ◽  
Stance Phase ◽  
Center Of Mass ◽  
Reaction Force ◽  
Sine Wave ◽  
Phase Method ◽  
Leg Stiffness ◽  
Mass Displacement ◽  
Male Subjects ◽  
Oscillation Method

Despite the presence of several different calculations of leg stiffness during hopping, little is known about how the methodologies produce differences in the leg stiffness. The purpose of this study was to directly compareKlegduring hopping as calculated from three previously published computation methods. Ten male subjects hopped in place on two legs, at four frequencies (2.2, 2.6, 3.0, and 3.4 Hz). In this article, leg stiffness was calculated from the natural frequency of oscillation (method A), the ratio of maximal ground reaction force (GRF) to peak center of mass displacement at the middle of the stance phase (method B), and an approximation based on sine-wave GRF modeling (method C). We found that leg stiffness in all methods increased with an increase in hopping frequency, butKlegvalues using methods A and B were significantly higher than when using method C at all hopping frequencies. Therefore, care should be taken when comparing leg stiffness obtained by method C with those calculated by other methods.

Running With an Elastic Lower Limb Exoskeleton

2016 ◽  
Vol 32 (3) ◽  
pp. 269-277 ◽  
Author(s):  
Michael S. Cherry ◽  
Sridhar Kota ◽  
Aaron Young ◽  
Daniel P. Ferris
Keyword(s):  
Lower Limb ◽  
Reaction Force ◽  
Metabolic Cost ◽  
Vertical Ground Reaction Force ◽  
Lower Limb Exoskeleton ◽  
Leg Stiffness ◽  
The Difference ◽  
Young Subjects ◽  
Electrical Motors ◽  
Human Running

Although there have been many lower limb robotic exoskeletons that have been tested for human walking, few devices have been tested for assisting running. It is possible that a pseudo-passive elastic exoskeleton could benefit human running without the addition of electrical motors due to the spring-like behavior of the human leg. We developed an elastic lower limb exoskeleton that added stiffness in parallel with the entire lower limb. Six healthy, young subjects ran on a treadmill at 2.3 m/s with and without the exoskeleton. Although the exoskeleton was designed to provide ~50% of normal leg stiffness during running, it only provided 24% of leg stiffness during testing. The difference in added leg stiffness was primarily due to soft tissue compression and harness compliance decreasing exoskeleton displacement during stance. As a result, the exoskeleton only supported about 7% of the peak vertical ground reaction force. There was a significant increase in metabolic cost when running with the exoskeleton compared with running without the exoskeleton (ANOVA, P < .01). We conclude that 2 major roadblocks to designing successful lower limb robotic exoskeletons for human running are human-machine interface compliance and the extra lower limb inertia from the exoskeleton.

scholarly journals Reliability of Unilateral Vertical Leg Stiffness Measures Assessed During Bilateral Hopping

2015 ◽  
Vol 31 (5) ◽  
pp. 285-291 ◽  
Author(s):  
Sean J. Maloney ◽  
Iain M. Fletcher ◽  
Joanna Richards
Keyword(s):  
Coefficient Of Variation ◽  
Center Of Mass ◽  
Reaction Force ◽  
Force Plate ◽  
Vertical Stiffness ◽  
Coefficients Of Variation ◽  
Leg Stiffness ◽  
Average Coefficient ◽  
Left And Right ◽  
Stiffness Profile

The assessment of vertical leg stiffness is an important consideration given its relationship to performance. Vertical stiffness is most commonly assessed during a bilateral hopping task. The current study sought to determine the intersession reliability, quantified by the coefficient of variation, of vertical stiffness during bilateral hopping when assessed for the left and right limbs independently, which had not been previously investigated. On 4 separate occasions, 10 healthy males performed 30 unshod bilateral hops on a dual force plate system with data recorded independently for the left and right limbs. Vertical stiffness was calculated as the ratio of peak ground reaction force to the peak negative displacement of the center of mass during each hop and was averaged over the sixth through tenth hops. For vertical stiffness, average coefficients of variation of 15.3% and 14.3% were observed for the left and right limbs, respectively. An average coefficient of variation of 14.7% was observed for bilateral vertical stiffness. The current study reports that calculations of unilateral vertical stiffness demonstrate reliability comparable to bilateral calculations. Determining unilateral vertical stiffness values and relative discrepancies may allow a coach to build a more complete stiffness profile of an individual athlete and better inform the training process.

scholarly journals The Influence of Different Playing Surfaces on the Biomechanics of a Tennis Running Forehand Foot Plant

2006 ◽  
Vol 22 (1) ◽  
pp. 14-24 ◽  
Author(s):  
Victoria H. Stiles ◽  
Sharon J. Dixon
Keyword(s):  
Surface Condition ◽  
Reaction Force ◽  
Force Plate ◽  
The Other ◽  
Biomechanical Analysis ◽  
Overuse Injuries ◽  
Joint Movement ◽  
Artificial Turf ◽  
Kinematic Data ◽  
Impact Forces

Research suggests that heightened impacts, altered joint movement patterns, and changes in friction coefficient from the use of artificial surfaces in sport increase the prevalence of overuse injuries. The purposes of this study were to (a) develop procedures to assess a tennis-specific movement, (b) characterize the ground reaction force (GRF) impact phases of the movement, and (c) assess human response during impact with changes in common playing surfaces. In relation to the third purpose it was hypothesized that surfaces with greatest mechanical cushioning would yield lower impact forces (PkFz) and rates of loading. Six shod volunteers performed 8 running forehand trials on each surface condition: baseline, carpet, acrylic, and artificial turf. Force plate (960 Hz) and kinematic data (120 Hz) were collected simultaneously for each trial. Running forehand foot plants are typically characterized by 3 peaks in vertical GRF prior to a foot-off peak. Group mean PkFz was significantly lower and peak braking force was significantly higher on the baseline surface compared with the other three test surfaces (p < 0.05). No significant changes in initial kinematics were found to explain unexpected PkFz results. The baseline surface yielded a significantly higher coefficient of friction compared with the other three test surfaces (p < 0.05). While the hypothesis is rejected, biomechanical analysis has revealed changes in surface type with regard to GRF variables.

scholarly journals Muscle mechanics and energy expenditure of the triceps surae during rearfoot and forefoot running

2018 ◽  
Author(s):  
Allison H. Gruber ◽  
Brian R. Umberger ◽  
Ross H. Miller ◽  
Joseph Hamill
Keyword(s):  
Energy Expenditure ◽  
Elastic Energy ◽  
Reaction Force ◽  
Metabolic Cost ◽  
Running Economy ◽  
Mechanical Work ◽  
Triceps Surae ◽  
Metabolic Energy ◽  
Forefoot Running ◽  
Metabolic Energy Expenditure

ABSTRACTForefoot running is advocated to improve running economy because of increased elastic energy storage than rearfoot running. This claim has not been assessed with methods that predict the elastic energy contribution to positive work or estimate muscle metabolic cost. The purpose of this study was to compare the mechanical work and metabolic cost of the gastrocnemius and soleus between rearfoot and forefoot running. Seventeen rearfoot and seventeen forefoot runners ran over-ground with their habitual footfall pattern (3.33-3.68m•s−1) while collecting motion capture and ground reaction force data. Ankle and knee joint angles and ankle joint moments served as inputs into a musculoskeletal model that calculated the mechanical work and metabolic energy expenditure of each muscle using Hill-based muscle models with contractile (CE) and series elastic (SEE) elements. A mixed-factor ANOVA assessed the difference between footfall patterns and groups (α=0.05). Forefoot running resulted in greater SEE mechanical work in the gastrocnemius than rearfoot running but no differences were found in CE mechanical work or CE metabolic energy expenditure. Forefoot running resulted in greater soleus SEE and CE mechanical work and CE metabolic energy expenditure than rearfoot running. The metabolic cost associated with greater CE velocity, force production, and activation during forefoot running may outweigh any metabolic energy savings associated with greater SEE mechanical work. Therefore, there was no energetic benefit at the triceps surae for one footfall pattern or the other. The complex CE-SEE interactions must be considered when assessing muscle metabolic cost, not just the amount of SEE strain energy.

scholarly journals Effect of Gait Speed on Recovery Motion from Tripping on a Treadmill

2021 ◽  
Vol 11 (17) ◽  
pp. 7908
Author(s):  
Yasuhiro Akiyama ◽  
Hazuki Miyata ◽  
Shogo Okamoto ◽  
Yoji Yamada
Keyword(s):  
Motion Capture ◽  
Principal Components ◽  
Gait Speed ◽  
Reaction Force ◽  
Force Plate ◽  
Principal Component ◽  
Individual Characteristics ◽  
Healthy Male ◽  
Gait Parameters ◽  
Male Subjects

The analysis of the mechanism of fall avoidance motion is required to prevent fall-related injuries. To investigate the factors that affect fall avoidance motion, tripping was induced among 10 healthy male subjects during treadmill walking at gait speeds of 3.5 and 4.0 km/h. The posture of the subjects and ground reaction force of the recovery steps were recorded using a motion capture system and force plate to analyze the effect of gait speed on recovery motion. The gait parameters of the recovery steps were calculated and compared between gait speeds. Principal component analysis was performed to identify the parameters that represent the recovery motion and the magnitude of the first and second recovery steps, and the balance of recovery steps were extracted as defining characteristics. Of the 18 gait parameters, such as step time, five differed depending on gait speeds. However, the other gait parameters and all four principal components did not differ significantly with respect to gait speeds. Furthermore, the distribution of principal components and gait parameters across subjects and gait speeds suggested that the variability between trials was greater than the effect of gait speed and individual characteristics on recovery motion.

Does Foot Anthropometry Predict Metabolic Cost During Running?

2017 ◽  
Vol 33 (5) ◽  
pp. 317-322 ◽  
Author(s):  
Herman van Werkhoven ◽  
Stephen J. Piazza
Keyword(s):  
Oxygen Consumption ◽  
Achilles Tendon ◽  
Body Height ◽  
Force Plate ◽  
Metabolic Cost ◽  
Running Economy ◽  
Metabolic Energy ◽  
Flexor Muscle ◽  
Reaction Forces ◽  
Tendon Force

Several recent investigations have linked running economy to heel length, with shorter heels being associated with less metabolic energy consumption. It has been hypothesized that shorter heels require larger plantar flexor muscle forces, thus increasing tendon energy storage and reducing metabolic cost. The goal of this study was to investigate this possible mechanism for metabolic cost reduction. Fifteen male subjects ran at 16 km⋅h−1 on a treadmill and subsequently on a force-plate instrumented runway. Measurements of oxygen consumption, kinematics, and ground reaction forces were collected. Correlational analyses were performed between oxygen consumption and anthropometric and kinetic variables associated with the ankle and foot. Correlations were also computed between kinetic variables (peak joint moment and peak tendon force) and heel length. Estimated peak Achilles tendon force normalized to body weight was found to be strongly correlated with heel length normalized to body height (r = −.751, p = .003). Neither heel length nor any other measured or calculated variable were correlated with oxygen consumption, however. Subjects with shorter heels experienced larger Achilles tendon forces, but these forces were not associated with reduced metabolic cost. No other anthropometric and kinetic variables considered explained the variance in metabolic cost across individuals.

scholarly journals Leg Stiffness and Vertical Stiffness of Habitual Forefoot and Rearfoot Strikers during Running

2020 ◽  
Vol 2020 ◽  
pp. 1-6
Author(s):  
Lulu Yin ◽  
Xiaoyue Hu ◽  
Zhangqi Lai ◽  
Kun Liu ◽  
Lin Wang
Keyword(s):  
Injury Risk ◽  
Loading Rate ◽  
Reaction Force ◽  
Running Economy ◽  
Initial Contact ◽  
Vertical Ground Reaction Force ◽  
Vertical Stiffness ◽  
Impact Peak ◽  
Leg Stiffness ◽  
Foot Strike

Foot strike patterns influence the running efficiency and may be an injury risk. However, differences in the leg stiffness between runners with habitual forefoot (hFFS) and habitual rearfoot (hRFS) strike patterns remain unclear. This study aimed at determining the differences in the stiffness, associated loading rate, and kinematic performance between runners with hFFS and hRFS during running. Kinematic and kinetic data were collected amongst 39 runners with hFFS and 39 runners with hRFS running at speed of 3.3 m/s, leg stiffness (Kleg), and vertical stiffness (Kvert), and impact loads were calculated. Results found that runners with hFFS had greater Kleg ( P = 0.010 , Cohe n ’ s   d = 0.60 ), greater peak vertical ground reaction force (vGRF) ( P = 0.040 , Cohe n ’ s   d = 0.47 ), shorter contact time( t c ) ( P < 0.001 , Cohe n ’ s   d = 0.85 ), and smaller maximum leg compression ( Δ L ) ( P = 0.002 , Cohe n ’ s   d = 0.72 ) compared with their hRFS counterparts. Runners with hFFS had lower impact peak (IP) ( P < 0.001 , Cohe n ’ s   d = 1.65 ), vertical average loading rate (VALR) ( P < 0.001 , Cohe n ’ s   d = 1.20 ), and vertical instantaneous loading rate (VILR) ( P < 0.001 , Cohe n ’ s   d = 1.14 ) compared with runners with hRFS. Runners with hFFS landed with a plantar flexed ankle, whereas runners with hRFS landed with a dorsiflexed ankle ( P < 0.001 , Cohe n ’ s   d = 3.35 ). Runners with hFFS also exhibited more flexed hip ( P = 0.020 , Cohe n ’ s   d = 0.61 ) and knee ( P < 0.001 , Cohe n ’ s   d = 1.15 ) than runners with hRFS at initial contact. These results might indicate that runners with hFFS were associated with better running economy through the transmission of elastic energy.

scholarly journals Biomechanical study on axillary crutches during single-leg swing-through gait

1986 ◽  
Vol 10 (2) ◽  
pp. 89-95 ◽  
Author(s):  
J. C. H. Goh ◽  
S. L. Toh ◽  
K. Bose
Keyword(s):  
Weight Bearing ◽  
Reaction Force ◽  
Force Plate ◽  
Primary Objective ◽  
Biomechanical Study ◽  
System A ◽  
Kinematic Study ◽  
Axillary Region ◽  
Male Subjects ◽  
Neurovascular Structures

This paper describes a kinetic and kinematic study on axillary crutches during one-leg swing-through gait. The primary objective is to evaluate the interplay of forces at the crutch and body interfaces and to relate them in the understanding of problems associated with the use of axillary crutches. Ten normal adult male subjects with simulated left leg impairment participated in the study. For data acquisition, the VICON kinematic system, a Kistler force plate and an instrumented crutch (with force transducers at the two upper struts close to the axillary bar and one near the crutch tip) were used. Results showed that the peak ground reaction force on the weight-bearing leg during lower limb stance increased by 21.6 percent bodyweight. The peak reaction force transmitted to the arm during crutch stancc was 44.4 percent bodyweight. These increased loadings could be detrimental to patients with unsound weight-bearing leg and upper extremities respectively. When the crutches were used incorrectly, 34 percent bodyweight was carried by the underarm. This could cause undue pressure over the neurovascular structures at the axillary region.

scholarly journals Limitations of Foot-Worn Sensors for Assessing Running Power

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 4952
Author(s):  
Tobias Baumgartner ◽  
Steffen Held ◽  
Stefanie Klatt ◽  
Lars Donath
Keyword(s):  
Time Use ◽  
Stride Length ◽  
Metabolic Cost ◽  
Running Economy ◽  
Accelerometer Data ◽  
Gait Characteristics ◽  
Significant Difference ◽  
Metabolic Costs ◽  
Ground Contact Time ◽  
Training Signal

Running power as measured by foot-worn sensors is considered to be associated with the metabolic cost of running. In this study, we show that running economy needs to be taken into account when deriving metabolic cost from accelerometer data. We administered an experiment in which 32 experienced participants (age = 28 ± 7 years, weekly running distance = 51 ± 24 km) ran at a constant speed with modified spatiotemporal gait characteristics (stride length, ground contact time, use of arms). We recorded both their metabolic costs of transportation, as well as running power, as measured by a Stryd sensor. Purposely varying the running style impacts the running economy and leads to significant differences in the metabolic cost of running (p < 0.01). At the same time, the expected rise in running power does not follow this change, and there is a significant difference in the relation between metabolic cost and power (p < 0.001). These results stand in contrast to the previously reported link between metabolic and mechanical running characteristics estimated by foot-worn sensors. This casts doubt on the feasibility of measuring running power in the field, as well as using it as a training signal.

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