The Vertical Displacement of the Center of Mass During Walking: A Comparison of Four Measurement Methods

1998 ◽  
Vol 120 (1) ◽  
pp. 133-139 ◽  
Author(s):  
M. Saini ◽  
D. C. Kerrigan ◽  
M. A. Thirunarayan ◽  
M. Duff-Raffaele
Keyword(s):  
Center Of Mass ◽  
Reaction Force ◽  
Vertical Displacement ◽  
The Body ◽  
The Other ◽  
Analysis Method ◽  
Force Measurements ◽  
Segmental Analysis ◽  
Significant Difference ◽  
The Difference

Measuring the vertical displacement of the center of mass (COM) of the body during walking may provide useful information about the energy required to walk. Four methods of varying complexity to estimate the vertical displacement of the COM were compared in 25 able-bodied, female subjects. The first method, the sacral marker method, utilized an external marker on the sacrum as representative of the COM of the body. The second method, the reconstructed pelvis method, which also utilized a marker over the sacrum, theoretically controlled for pelvic tilt motion. The third method, the segmental analysis method, involved measuring motion of the trunk and limb segments. The fourth method, the forceplate method, involved estimating the COM displacement from ground reaction force measurements. A two-tailed paired t-test within an ANOVA showed no statistically significant difference between the sacral marker and the reconstructed pelvis methods (p = 0.839). There was also no statistically significant difference between the sacral marker and the segmental analysis method (p = 0.119) or between the reconstructed pelvis and the segmental analysis method (p = 0.174). It follows that the first method, which is the most simple, can provide essentially the same estimate of the vertical displacement of the COM as the more complicated second and third measures. The forceplate method produced data with a lower range and a different distribution than the other three methods. There was a statistically significant difference between the forceplate method and the other methods (p < 0.01 for each of the three comparisons). The forceplate method provides information that is statistically significantly different from the results of the kinematic methods. The magnitude of the difference is large enough to be physiologically significant and further studies to define the sources of the differences and the relative validity of the two approaches are warranted.

A treadmill-mounted force platform

1989 ◽  
Vol 67 (4) ◽  
pp. 1692-1698 ◽  
Author(s):  
R. Kram ◽  
A. J. Powell
Keyword(s):  
Full Range ◽  
Center Of Mass ◽  
Reaction Force ◽  
Vertical Displacement ◽  
The Body ◽  
Force Platform ◽  
Vertical Force ◽  
Vertical Ground Reaction Force ◽  
Contact Phase ◽  
Frictional Forces

Muscle, bone, and tendon forces; the movement of the center of mass, and the spring properties of the body during terrestrial locomotion can be measured using ground-mounted force platforms. These measurements have been extremely time consuming because of the difficulty in obtaining repeatable constant speed trials (particularly with animals). We have overcome this difficulty by mounting a force platform directly under the belt of a motorized treadmill. With this arrangement, vertical force can be recorded from an unlimited number of successive ground contacts in a much shorter time. With this treadmill-mounted force platform it is possible to accurately make the following measurements over the full range of steady speeds and under various perturbations of normal gait: 1) vertical ground reaction force over the course of the contact phase; 2) peak forces in bone, muscle, and tendon; 3) the vertical displacement of the center of mass; and 4) contact time for the limbs. In our treadmill-force platform design, belt forces and frictional forces cause no measurable cross-talk problem. Natural frequency (160 Hz), nonlinearity (less than 5%), and position independence (less than 2%) are all quite acceptable. Motor-caused vibrations are greater than 150 Hz and thus can be easily filtered.

scholarly journals Design of a load carriage system oriented to reduce acceleration forces when carrying a backpack

2019 ◽  
pp. 34-43
Author(s):  
Camilo Eduardo Pérez-Cualtán ◽  
Oscar Iván Campo-Salazar
Keyword(s):  
Body Weight ◽  
Energy Expenditure ◽  
Center Of Mass ◽  
Reaction Force ◽  
Vertical Displacement ◽  
The Body ◽  
Load Carriage ◽  
Vertical Ground Reaction Force ◽  
Military Life ◽  
Vertical Ground

In military life, load carriage is an unavoidable part of field operations which is the reason why soldiers often make use of a military backpack. Infantry soldiers usually carry loads weighting more than 30% of their body weight. When the soldier carries a certain weight, his energy expenditure increases, which causes a reduction in performance. The transported load has a movement similar to the vertical displacement of the center of mass of the soldier while walking. This leads to a significant increase in the acceleration forces generated by the action of said load on the body which explains the increase in energy expenditure. The objective of this project was to develop a load carriage system that suspends the load and reduces its vertical displacement. Results show a reduction in both the vertical excursion of the load and in the total vertical ground reaction force when carrying a load with the developed prototype, with respect to the conventional military backpack.

Comparison between Kinematic and Kinetic Methods for Computing the Vertical Displacement of the Center of Mass during Human Hopping at Different Frequencies

2008 ◽  
Vol 24 (3) ◽  
pp. 271-279 ◽  
Author(s):  
Alberto Ranavolo ◽  
Romildo Don ◽  
Angelo Cacchio ◽  
Mariano Serrao ◽  
Marco Paoloni ◽  
...  
Keyword(s):  
Significant Interaction ◽  
Large Range ◽  
Center Of Mass ◽  
Vertical Displacement ◽  
Force Platform ◽  
Segmental Analysis ◽  
Post Hoc Analysis ◽  
Kinetic Methods ◽  
Significant Difference ◽  
Post Hoc

Kinematic and kinetic methods (sacral marker, reconstructed pelvis, segmental analysis, and force platform methods) have been used to calculate the vertical excursion of the center of mass (COM) during movement. In this study we compared the measurement of vertical COM displacement yielded by different methods during able-bodied subjects’ hopping at different frequencies (varying between 1.2 and 3.2 Hz). ANOVA revealed a significant interaction between hopping frequency and method (p< 0.001), showing that increasing hopping frequency reduced the differences between methods. A post hoc analysis revealed a significant difference between all methods at the lowest hopping frequency and between the force platform and both the sacral marker and reconstructed pelvis methods at the intermediate hopping frequencies, with differences ranging from 16 to 67 millimeters (allp< 0.05). Results are discussed in view of each methods’ limits. We conclude that the segmental analysis and force platform methods can be considered to provide the most accurate results for COM vertical excursion during human hopping in a large range of hopping frequency.

A Comparison of Vertical Stiffness Values Calculated from Different Measures of Center of Mass Displacement in Single-Leg Hopping

2017 ◽  
Vol 33 (1) ◽  
pp. 39-47 ◽  
Author(s):  
Kurt L. Mudie ◽  
Amitabh Gupta ◽  
Simon Green ◽  
Hiroaki Hobara ◽  
Peter J. Clothier
Keyword(s):  
Center Of Mass ◽  
Reaction Force ◽  
Force Plate ◽  
Analysis Method ◽  
Vertical Ground Reaction Force ◽  
Integration Methods ◽  
Segmental Analysis ◽  
Vertical Stiffness ◽  
Double Integration ◽  
Marker Cluster

This study assessed the agreement between Kvert calculated from 4 different methods of estimating vertical displacement of the center of mass (COM) during single-leg hopping. Healthy participants (N = 38) completed a 10-s single-leg hopping effort on a force plate, with 3D motion of the lower limb, pelvis, and trunk captured. Derived variables were calculated for a total of 753 hop cycles using 4 methods, including: double integration of the vertical ground reaction force, law of falling bodies, a marker cluster on the sacrum, and a segmental analysis method. Bland-Altman plots demonstrated that Kvert calculated using segmental analysis and double integration methods have a relatively small bias (0.93 kN⋅m–1) and 95% limits of agreement (–1.89 to 3.75 kN⋅m–1). In contrast, a greater bias was revealed between sacral marker cluster and segmental analysis (–2.32 kN⋅m–1), sacral marker cluster and double integration (–3.25 kN⋅m–1), and the law of falling bodies compared with all methods (17.26–20.52 kN⋅m–1). These findings suggest the segmental analysis and double integration methods can be used interchangeably for the calculation of Kvert during single-leg hopping. The authors propose the segmental analysis method to be considered the gold standard for the calculation of Kvert during single-leg, on-the-spot hopping.

Perbedaan Penggunaan Antikoagulan K2EDTA DAN K3EDTA Terhadap Hasil Pemeriksaan Indeks Eritrosit

2018 ◽  
Vol 1 (2) ◽  
pp. 114
Author(s):  
Wahdaniah Wahdaniah ◽  
Sri Tumpuk
Keyword(s):  
Screening Test ◽  
Venous Blood ◽  
The Body ◽  
Ethylene Diamine ◽  
P Value ◽  
Cross Sectional ◽  
Significant Difference ◽  
Ethylene Diamine Tetra Acetate ◽  
The Difference ◽  
Index Value

Abstract: Routine blood examination is the earliest blood test or screening test to determine the diagnosis of an abnormality. Blood easily froze if it is outside the body and can be prevented by the addition of anticoagulants, one of which Ethylene Diamine Tetra Acetate (EDTA). Currently available vacuum tubes containing EDTA anticoagulants in the form of K2EDTA and K3EDTA. K3EDTA is usually a salt that has better stability than other EDTA salts because it shows a pH approaching a blood pH of about 6.4. The purpose of this research is to know the difference of erythrocyte index results include MCH, MCV and MCHC using K3EDTA anticoagulant with K2EDTA. This research is a cross sectional design. This study used venous blood samples mixed with K2EDTA anticoagulant and venous blood mixed with K3EDTA anticoagulants, each of 30 samples. Data were collected and analyzed using paired different test. Based on data analysis that has been done on MCH examination, p value <0,05 then there is a significant difference between samples with K3EDTA anticoagulant with K2EDTA to erythrocyte index value. Then on the examination of MCV and MCHC obtained p value <0.05 then there is no significant difference between samples with K3EDTA anticoagulant with K2EDTA to erythrocyte index value.Abstrak: Pemeriksaan darah rutin merupakan pemeriksaan darah yang paling awal atau screening test untuk mengetahui diagnosis suatu kelainan. Darah mudah membeku jika berada diluar tubuh dan bisa dicegah dengan penambahan antikoagulan, salah satunya Ethylene Diamine Tetra Acetate (EDTA). Dewasa ini telah tersedia tabung vakum yang sudah berisi antikoagulan EDTA dalam bentuk  K2EDTA dan  K3EDTA. K3EDTA  biasanya berupa garam yang mempunyai stabilitas yang lebih baik dari garam EDTA yang lain karena menunjukkan pH yang mendekati pH darah yaitu sekitar 6,4. Tujuan dari penelitian ini adalah untuk mengetahui perbedaan hasil indeks eritrosit meliputi MCH, MCV dan MCHC menggunakan antikoagulan K3EDTA dengan K2EDTA. Penelitian ini merupakan penelitian dengan desain cross sectional. Penelitian ini menggunakan sampel darah vena yang dicampur dengan antikoagulan K2EDTA dan darah vena yang dicampur dengan antikoagulan K3EDTA, masing-masing sebanyak 30 sampel. Data dikumpulkan dan dianalisis menggunakan uji beda berpasangan. Berdasarkan analisis data yang telah dilakukan pada pemeriksaan MCH didapatkan nilai p < 0,05 maka ada perbedaan yang signifikan antara sampel dengan antikoagulan K3EDTA dengan K2EDTA terhadap nilai indeks eritrosit. Kemudian pada pemeriksaan MCV dan MCHC didapatkan nilai p < 0,05 maka tidak ada perbedaan yang signifikan antara sampel dengan antikoagulan K3EDTA dengan K2EDTA terhadap nilai indeks eritrosit.

scholarly journals The Respiration of some Planktonic copepods II. The Effect Of Temperature

1953 ◽  
Vol 31 (3) ◽  
pp. 447-460 ◽  
Author(s):  
D. T. Gauld ◽  
J. E. G. Raymont
Keyword(s):  
Respiratory Rate ◽  
The Body ◽  
The Other ◽  
Effect Of Temperature ◽  
Acartia Clausi ◽  
Temora Longicornis ◽  
Different Temperatures ◽  
Planktonic Copepods ◽  
The Difference ◽  
The Relationship

The respiratory rates of three species of planktonic copepods, Acartia clausi, Centropages hamatus and Temora longicornis, were measured at four different temperatures.The relationship between respiratory rate and temperature was found to be similar to that previously found for Calanus, although the slope of the curves differed in the different species.The observations on Centropages at 13 and 170 C. can be divided into two groups and it is suggested that the differences are due to the use of copepods from two different generations.The relationship between the respiratory rates and lengths of Acartia and Centropages agreed very well with that previously found for other species. That for Temora was rather different: the difference is probably due to the distinct difference in the shape of the body of Temora from those of the other species.The application of these measurements to estimates of the food requirements of the copepods is discussed.

scholarly journals The difference in pediatric blood pressure between middle childhood and late childhood prior to dental treatment

2018 ◽  
Vol 25 (1) ◽  
Author(s):  
Fitri Anissa Syaimima Syaiful Azim ◽  
Arlette Suzy Puspa Pertiwi ◽  
Rosiliwati Wihardja
Keyword(s):  
Blood Pressure ◽  
Middle Childhood ◽  
Dental Treatment ◽  
Systolic Pressure ◽  
The Body ◽  
Late Childhood ◽  
Test Analysis ◽  
Mean Values ◽  
Significant Difference ◽  
The Difference

Every child will go through several stages in his or her life. They are different from each other as they are in the process of development of cognition, physics, emotion, and personality. For many children, a visit to the dentist can raise their anxiety. This anxiousness will lead to stress that influences the cardiovascular function in the body. The purpose of this research was to determine the difference in pediatric blood pressure between middle childhood and late childhood prior to dental treatment. This research was a clinical trial, pure experimental study. The sample consisted of 30 children within the range of 4-12 years old where they were divided into two groups of age; middle childhood (4-7 years old) and late childhood (8-12 years old). The blood pressures were measured before any dental treatment began and the values were recorded. The data were then analyzed using the One-Sample T-Test analysis. The results of blood pressure in middle childhood and late childhood were compared to the average mean values for each age group. It showed that there was a significant difference in the systolic pressure, which was found higher in the middle childhood group compared to the late childhood. From the result can be concluded that there was a difference in the pediatric blood pressure between middle childhood and late childhood prior to dental treatment.

scholarly journals PERBANDINGAN KUALITAS PRODUK DAN MINAT MENABUNG PADA LPD DESA ADAT TAJUN DENGAN DESA ADAT TEGAL

2020 ◽  
Vol 4 (1) ◽  
pp. 59-67
Author(s):  
Eka Swarnadi Luh ◽  
Ketut Budi Susrusa ◽  
Ida Ayu Listia Dewi
Keyword(s):  
Product Quality ◽  
Financial Institutions ◽  
Rapid Development ◽  
Research Data ◽  
The Other ◽  
Physical Evidence ◽  
Significant Difference ◽  
The Difference ◽  
Better Than

LPDs are non-bank financial institutions that are regulated and approved by the Regional Regulations of the Province of Bali. The management of LPD is fully handed over to the relevant Pakraman village. In line with the rapid development of LPDs, it turns out that on the other hand it shows diverse performance, so that LPDs need to pay attention to the level of product quality and customer interest in the products offered.            The purpose of the study was to determine the comparison of product quality and interest in saving at the Tajun Traditional Village LPD with the Traditional Village of Tegal. The number of samples from Tajun Adat Village LPD was 98 people and the LPD of Tegal Traditional Village was 84 people. The research data were analyzed by the Mann-Whitney Test. The results showed that there was a significant difference between the quality of the products of the Adat Village of Tajun LPD and the Traditional Village of Tegal. This difference is indicated by indicators of physical evidence, reliability, responsiveness and empathy. The product quality of Tajun Adat Village's LPD is better than the traditional village of Tegal. There is a significant difference between the interest in saving the traditional village of Tajun LPD and the traditional village of Tegal. The difference is in the indicator of confidence. Interest in Saving Tajun Indigenous Village LPD is higher than the Traditional Village of Tegal.

Effect of Hopping Frequency on Bilateral Differences in Leg Stiffness

2013 ◽  
Vol 29 (1) ◽  
pp. 55-60 ◽  
Author(s):  
Hiroaki Hobara ◽  
Koh Inoue ◽  
Kazuyuki Kanosue
Keyword(s):  
Ground Reaction Force ◽  
Center Of Mass ◽  
Reaction Force ◽  
Human Movement ◽  
Vertical Ground Reaction Force ◽  
Mass Model ◽  
Lower Extremity Injuries ◽  
Leg Stiffness ◽  
Significant Difference ◽  
Bilateral Differences

Understanding the degree of leg stiffness during human movement would provide important information that may be used for injury prevention. In the current study, we investigated bilateral differences in leg stiffness during one-legged hopping. Ten male participants performed one-legged hopping in place, matching metronome beats at 1.5, 2.2, and 3.0 Hz. Based on a spring-mass model, we calculated leg stiffness, which is defined as the ratio of maximal ground reaction force to maximum center of mass displacement at the middle of the stance phase, measured from vertical ground reaction force. In all hopping frequency settings, there was no significant difference in leg stiffness between legs. Although not statistically significant, asymmetry was the greatest at 1.5 Hz, followed by 2.2 and 3.0 Hz for all dependent variables. Furthermore, the number of subjects with an asymmetry greater than the 10% criterion was larger at 1.5 Hz than those at 2.2 and 3.0 Hz. These results will assist in the formulation of treatment-specific training regimes and rehabilitation programs for lower extremity injuries.

scholarly journals SVOC Concentrations in House dust and Residential Environment in Japanese Houses

2019 ◽  
Vol 111 ◽  
pp. 06060
Author(s):  
Hoon KIM ◽  
Yohei INABA ◽  
Kanae BEKKI ◽  
Motoya HAYASHI ◽  
Kenichi AZUMA ◽  
...  
Keyword(s):  
Particle Size ◽  
House Dust ◽  
Concentration Distribution ◽  
Oral Intake ◽  
Living Environment ◽  
The Other ◽  
Component Ratio ◽  
Analysis Method ◽  
Residential Environments ◽  
Significant Difference

This study aims to investigate the relevance of between SVOC concentrations in house dust and living environments. Using the newly proposed dust collecting and SVOC analysis method, we determined concentrations of the nine SVOC substances by dust size and made simultaneously the questionnaire about residential environments. Collected dusts were screened with sieves and then analyzed on nine components (DEP, DMP, BBP, DEHP, DINP, DBP, DNOP, DIDP, DIBP) by LC/MS/MS method. The results leaded to selecting less than 100μm and 100-250μm as the target size of dusts to be investigated intensively by considering the concentration distribution and the oral intake of humans. DEHP and DINP accounted for 96 to 97% of determined amount of SVOC and only the small amounts in the other seven components were detected. There was no significant difference in the component ratio depending on particle size. Significant difference was obtained between a few substances of SVOC and several living environment items.

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