Effects of stride frequency and foot position at landing on braking force, hip torque, impact peak force and the metabolic cost of running in humans

To examine the effects of variation in body form on the mechanics of terrestrial locomotion, we used a miniature force platform to measure the ground reaction forces of the smallest and, relative to its mass, one of the fastest invertebrates ever studied, the American cockroach Periplaneta americana (mass = 0.83 g). From 0.44-1.0 ms-1, P. americana used an alternating tripod stepping pattern. Fluctuations in gravitational potential energy and horizontal kinetic energy of the center of mass were nearly in phase, characteristic of a running or bouncing gait. Aerial phases were observed as vertical ground reaction force approached zero at speeds above 1 ms-1. At the highest speeds (1.0-1.5 ms-1 or 50 body lengths per second), P. americana switched to quadrupedal and bipedal running. Stride frequency approached the wing beat frequencies used during flight (27 Hz). High speeds were attained by increasing stride length, whereas stride frequency showed little increase with speed. The mechanical power used to accelerate the center of mass increased curvilinearly with speed. The mass-specific mechanical energy used to move the center of mass a given distance was similar to that measured for animals five orders of magnitude larger in mass, but was only one-hundredth of the metabolic cost.

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Animal galloping and human hopping: an energetics and biomechanics laboratory exercise

AJP Advances in Physiology Education ◽

10.1152/advan.00045.2013 ◽

2013 ◽

Vol 37 (4) ◽

pp. 377-383 ◽

Cited By ~ 3

Author(s):

Stan L. Lindstedt ◽

Patrick M. Mineo ◽

Paul J. Schaeffer

Keyword(s):

Body Size ◽

Metabolic Cost ◽

Mechanical Efficiency ◽

Lessons Learned ◽

Stride Frequency ◽

Energetic Cost ◽

Elastic Recoil ◽

Laboratory Exercise ◽

The Cost ◽

Work Done

This laboratory exercise demonstrates fundamental principles of mammalian locomotion. It provides opportunities to interrogate aspects of locomotion from biomechanics to energetics to body size scaling. It has the added benefit of having results with robust signal to noise so that students will have success even if not “meticulous” in attention to detail. First, using respirometry, students measure the energetic cost of hopping at a “preferred” hop frequency. This is followed by hopping at an imposed frequency half of the preferred. By measuring the O2 uptake and work done with each hop, students calculate mechanical efficiency. Lessons learned from this laboratory include 1) that the metabolic cost per hop at half of the preferred frequency is nearly double the cost at the preferred frequency; 2) that when a person is forced to hop at half of their preferred frequency, the mechanical efficiency is nearly that predicted for muscle but is much higher at the preferred frequency; 3) that the preferred hop frequency is strongly body size dependent; and 4) that the hop frequency of a human is nearly identical to the galloping frequency predicted for a quadruped of our size. Together, these exercises demonstrate that humans store and recover elastic recoil potential energy when hopping but that energetic savings are highly frequency dependent. This stride frequency is dependent on body size such that frequency is likely chosen to maximize this function. Finally, by requiring students to make quantitative solutions using appropriate units and dimensions of the physical variables, these exercises sharpen analytic and quantitative skills.

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Mechanical and metabolic profile of locomotion in adults with childhood-onset GH deficiency

Acta Endocrinologica ◽

10.1530/eje.0.1420035 ◽

2000 ◽

pp. 35-41 ◽

Cited By ~ 20

Author(s):

AE Minetti ◽

LP Ardigo ◽

F Saibene ◽

S Ferrero ◽

A Sartorio

Keyword(s):

Gh Deficiency ◽

Mechanical Energy ◽

Metabolic Cost ◽

Open Circuit ◽

Stride Frequency ◽

Healthy Controls ◽

Childhood Onset ◽

External Work ◽

Metabolic Role ◽

All Speeds

OBJECTIVE: The aim of the present study was to evaluate the energy cost and the mechanical work of locomotion in a group of adults with childhood-onset GH deficiency (GHD). SUBJECTS: Eight males with childhood-onset GHD (mean age+/-s.d.: 31.7+/-3.6 years; mean height: 145.1+/-6.7cm) and six age-, sex- and exercise-matched normal subjects were studied. DESIGN: GHD patients and healthy controls were requested to walk and run in the speed range of 2-11km h(-1). For each condition, simultaneous mechanical and metabolic measurements were taken. METHODS: Oxygen consumption, and mechanical internal and external work of locomotion were evaluated with standard open-circuit respirometry and three-dimensional motion analysis respectively. RESULTS: External work was not significantly different between GHD patients and healthy controls, while internal work was higher for patients at all speeds. In walking, the relationships between both the mechanical energy recovery and the metabolic cost with speed were shifted towards lower speeds in patients. As a consequence, the optimal speed of walking, i.e. the speed at which the cost of locomotion is minimum, was lower for GHD patients. Stride frequency was significantly higher (11.2-11.3%) for GHD patients at all speeds of walking and running. GHD patients were unable to run at speeds higher than 8km h(-1) for the time needed to reach a metabolic steady state. CONCLUSION: It appears that both the mechanics and energetics of locomotion in short-statured adults with childhood-onset GHD are not strikingly different from those of healthy controls, thus demonstrating a substantial 'normality' in this group of GHD patients at metabolically attainable speeds. The 'harmonic' body structure and the adherence to allometric transformations in these patients do not exclude the possibility of a different metabolic role of GH in normally statured adults with childhood-onset GHD and in those with acquired GHD, taking into account the well recognized heterogeneity of the adult GHD syndrome.

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Impact peak force measurement of potato

International Journal of Food Properties ◽

10.1080/10942912.2020.1751655 ◽

2020 ◽

Vol 23 (1) ◽

pp. 616-626

Author(s):

Weigang Deng ◽

Chunguang Wang ◽

Shengshi Xie

Keyword(s):

Force Measurement ◽

Peak Force ◽

Impact Peak

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Factors in fatigue during intermittent electrical stimulation of human skeletal muscle

Journal of Applied Physiology ◽

10.1152/japplphysiol.01010.2001 ◽

2002 ◽

Vol 93 (2) ◽

pp. 469-478 ◽

Cited By ~ 31

Author(s):

David W. Russ ◽

Krista Vandenborne ◽

Stuart A. Binder-Macleod

Keyword(s):

Electrical Stimulation ◽

Low Frequency ◽

Metabolic Cost ◽

Peak Force ◽

Medial Gastrocnemius ◽

Single Frequency ◽

High Frequency Stimulation ◽

Frequency Stimulation ◽

Low Frequency Fatigue ◽

Force Time

During an electrically elicited isometric contraction, the metabolic cost of attaining is greater than of maintaining force. Thus fatigue produced during such stimulation may not simply be a function of the force-time integral (FTI), as previously suggested. The goal of the present study was to evaluate fatigue produced in human medial gastrocnemius by intermittent, isometric electrical stimulation with trains of different frequencies (20, 40, or 80 Hz) and durations (300, 600, or 1,200 ms) that produced different peak forces and FTIs. Each subject ( n = 10) participated in a total of six sessions. During each session, subjects received a pre- and postfatigue testing protocol and a different, 150-train fatiguing protocol. Each fatiguing protocol used only a single frequency and duration. The fatigue produced by the different protocols was correlated to the initial peak force of the fatiguing protocols ( r 2= 0.74–0.85) but not to the initial or total FTI. All of the protocols tested produced a proportionately greater impairment of force in response to low- vs. high-frequency stimulation (i.e., low-frequency fatigue). There was no effect of protocol on low-frequency fatigue, suggesting that all the protocols produced comparable levels of impairment in excitation-contraction coupling. These results suggest that, for brief stimulated contractions, peak force is a better predictor of fatigue than FTI, possibly because of the different metabolic demands of attaining and maintaining force.

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Collision simulation of potato on rod separator

International Journal of Food Engineering ◽

10.1515/ijfe-2020-0233 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Weigang Deng ◽

Chunguang Wang ◽

Shengshi Xie

Keyword(s):

Contact Stress ◽

Structural Parameters ◽

Peak Force ◽

Optimized Design ◽

Drop Height ◽

Element Analysis ◽

Impact Peak ◽

The Finite Element Analysis ◽

Working Parameters ◽

The Impact

Abstract To obtain the collision characteristics of potatoes colliding with steel rods of different parameters, the finite element analysis (FEA) method was used to study the impact contact stress, collision displacement, acceleration and impact force. The results showed that with increasing rod diameter, the maximum collision displacement of the potato in the Y direction decreased, and the maximum collision acceleration and impact peak force increased. With increasing rod tilt angle and rod spacing, the maximum collision displacement increased linearly, but the maximum collision acceleration and impact peak force decreased linearly. Within the range of analysis factors, the fluctuation of the maximum collision displacement, acceleration and impact peak force caused by the change in rod diameters were the smallest, which were 0.34 mm, 38 m/s2 and 9 N, respectively. When potatoes collided with single and double rods, all the collision characteristics increased with the increase in potato drop height, and the results for double rods were significantly smaller than those for single rod collision. When the potato mass was 250 g, the drop height was 200 mm for single rod collision or 250 mm for double rod collision, the impact contact stress reached the yield stress, and the potato was damaged. This article provides a data basis and a referenced method for the optimized design of the structural parameters and working parameters of the rod separator in the process of potato mechanized harvesting.

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TEST RESEARCH ON THE IMPACT PEAK FORCE AND DAMAGE DEPTH OF POTATO

INMATEH Agricultural Engineering ◽

10.35633/inmateh-61-12 ◽

2020 ◽

Vol 61 (2) ◽

pp. 105-114

Author(s):

Weigang Deng ◽

Chunguang Wang ◽

Shengshi Xie

Keyword(s):

Influence Factors ◽

Orthogonal Test ◽

Peak Force ◽

Drop Height ◽

Single Factor ◽

Potato Varieties ◽

Impact Peak ◽

Damage Depth ◽

The Impact

To analyse the influence factors of impact peak force (IPF) and damage depth (DD) on potatoes, the orthogonal test and single factor test were carried out on two potato varieties. The results showed that the IPF of Xiabodi was smaller and DD was greater than those of Gaoyuanhong. Potato mass had the greatest effect on IPF, and that of drop height on DD. The equations between IPF, DD and potato mass, drop height were obtained. Both IPF and DD impacting with steel were the largest, and the smallest with steel- rubber. With the increase of impact times, IPF decreased first and then increased, and DD increased gradually.

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Gait changes in a line of mice artificially selected for longer limbs

PeerJ ◽

10.7717/peerj.3008 ◽

2017 ◽

Vol 5 ◽

pp. e3008 ◽

Cited By ~ 5

Author(s):

Leah M. Sparrow ◽

Emily Pellatt ◽

Sabrina S. Yu ◽

David A. Raichlen ◽

Herman Pontzer ◽

...

Keyword(s):

Stride Length ◽

Stance Phase ◽

Metabolic Cost ◽

Limb Length ◽

Stride Frequency ◽

Practical Reasons ◽

Cost Of Transport ◽

Terrestrial Locomotion ◽

Hind Limbs ◽

Body Sizes

In legged terrestrial locomotion, the duration of stance phase, i.e., when limbs are in contact with the substrate, is positively correlated with limb length, and negatively correlated with the metabolic cost of transport. These relationships are well documented at the interspecific level, across a broad range of body sizes and travel speeds. However, such relationships are harder to evaluate within species (i.e., where natural selection operates), largely for practical reasons, including low population variance in limb length, and the presence of confounding factors such as body mass, or training. Here, we compared spatiotemporal kinematics of gait in Longshanks, a long-legged mouse line created through artificial selection, and in random-bred, mass-matched Control mice raised under identical conditions. We used a gait treadmill to test the hypothesis that Longshanks have longer stance phases and stride lengths, and decreased stride frequencies in both fore- and hind limbs, compared with Controls. Our results indicate that gait differs significantly between the two groups. Specifically, and as hypothesized, stance duration and stride length are 8–10% greater in Longshanks, while stride frequency is 8% lower than in Controls. However, there was no difference in the touch-down timing and sequence of the paws between the two lines. Taken together, these data suggest that, for a given speed, Longshanks mice take significantly fewer, longer steps to cover the same distance or running time compared to Controls, with important implications for other measures of variation among individuals in whole-organism performance, such as the metabolic cost of transport.

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Relevance of Frequency-Domain Analyses to Relate Shoe Cushioning, Ground Impact Forces and Running Injury Risk: A Secondary Analysis of a Randomized Trial With 800+ Recreational Runners

Frontiers in Sports and Active Living ◽

10.3389/fspor.2021.744658 ◽

2021 ◽

Vol 3 ◽

Author(s):

Laurent Malisoux ◽

Paul Gette ◽

Anne Backes ◽

Nicolas Delattre ◽

Jan Cabri ◽

...

Keyword(s):

Frequency Domain ◽

High Frequency ◽

Injury Risk ◽

Peak Force ◽

Recent Trial ◽

Frequency Signal ◽

High Frequency Signal ◽

Impact Forces ◽

Impact Peak ◽

Force Characteristics

Cushioning systems in running shoes are used assuming that ground impact forces relate to injury risk and that cushioning materials reduce these impact forces. In our recent trial, the more cushioned shoe version was associated with lower injury risk. However, vertical impact peak force was higher in participants with the Soft shoe version. The primary objective of this study was to investigate the effect of shoe cushioning on the time, magnitude and frequency characteristics of peak forces using frequency-domain analysis by comparing the two study groups from our recent trial (Hard and Soft shoe group, respectively). The secondary objective was to investigate if force characteristics are prospectively associated with the risk of running-related injury. This is a secondary analysis of a double-blinded randomized trial on shoe cushioning with a biomechanical running analysis at baseline and a 6-month follow-up on running exposure and injury. Participants (n = 848) were tested on an instrumented treadmill at their preferred running speed in their randomly allocated shoe condition. The vertical ground reaction force signal for each stance phase was decomposed into the frequency domain using the discrete Fourier transform. Both components were recomposed into the time domain using the inverse Fourier transform. An analysis of variance was used to compare force characteristics between the two study groups. Cox regression analysis was used to investigate the association between force characteristics and injury risk. Participants using the Soft shoes displayed lower impact peak force (p < 0.001, d = 0.23), longer time to peak force (p < 0.001, d = 0.25), and lower average loading rate (p < 0.001, d = 0.18) of the high frequency signal compared to those using the Hard shoes. Participants with low average and instantaneous loading rate of the high frequency signal had lower injury risk [Sub hazard rate ratio (SHR) = 0.49 and 0.55; 95% Confidence Interval (CI) = 0.25–0.97 and 0.30–0.99, respectively], and those with early occurrence of impact peak force (high frequency signal) had greater injury risk (SHR = 1.60; 95% CI = 1.05–2.53). Our findings may explain the protective effect of the Soft shoe version previously observed. The present study also demonstrates that frequency-domain analyses may provide clinically relevant impact force characteristics.Clinical Trial Registration:https://clinicaltrials.gov/, identifier: 9NCT03115437.

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