scholarly journals Gravity center estimation for evaluation of standing whole body compensation using virtual barycentremetry based on biplanar slot-scanning stereoradiography - validation by simultaneous force plate measurement

2022 ◽  
Vol 23 (1) ◽  
Author(s):  
Kazuhiro Hasegawa ◽  
Celia Amabile ◽  
Matthieu Nesme ◽  
Jean Dubousset
Keyword(s):  
Body Weight ◽  
Imaging System ◽  
Center Of Mass ◽  
Intraclass Correlation ◽  
Force Plate ◽  
Whole Body ◽  
Gravity Center ◽  
3 Dimensional ◽  
Gravity Line ◽  
Full Body

Abstract Background Whole body standing alignment (WBSA) in terms of biomechanics can be evaluated accurately only by referring the gravity line (GL) which lies on the gravity center (GC). Here, we introduce a method for estimating GL and simultaneous WBSA measurement using the EOS® imaging system and report on the reproducibility and reliability of the method. Methods A 3-dimensional (3D) avatar to estimate GC was created following three steps: 3D reconstruction of the bone based on EOS images; deformation into a generic morphotype (MakeHuman statistical model) before density integration with 3D rasterization of the full body into 1-mm3 voxels (the content of each voxel is considered homogeneous); computation of the density of all the voxels provides the center of mass, which can be projected onto the floor as the GC of the full body, providing the GL in relation to the WBSA. The repeatability, reproducibility, and accuracy of the estimated GC and body weight of the avatar were compared with clinical estimation using a force plate in healthy volunteers and patients with degenerative and deformative diseases. Results Statistical analyses of the data revealed that the repeatability and reproducibility of the estimation was high with intra-rater and inter-rater intraclass correlation coefficient. ≥0.999. The coordinate values of the GC and body weight estimation did not differ significantly between the avatar and force plate measurements, demonstrating the high accuracy of the method. Conclusion This new method of estimating GC and WBSA is reliable and accurate. Application of this method could allow clinicians to quickly and qualitatively evaluate WBSA with GL with various spinal malalignment pathologies.

Quantifying Segmental Contributions to Center-of-Mass Motion During Dynamic Continuous Support Surface Perturbations Using Simplified Estimation Models

2020 ◽  
Vol 36 (4) ◽  
pp. 198-208
Author(s):  
Alison Schinkel-Ivy ◽  
Vicki Komisar ◽  
Carolyn A. Duncan
Keyword(s):  
Balance Control ◽  
Center Of Mass ◽  
Three Dimensional ◽  
The Body ◽  
Whole Body ◽  
Mass Motion ◽  
Support Surface ◽  
Body Segments ◽  
Body Model ◽  
Full Body

Investigating balance reactions following continuous, multidirectional, support surface perturbations is essential for improving our understanding of balance control in moving environments. Segmental motions are often incorporated into rapid balance reactions following external perturbations to balance, although the effects of these motions during complex, continuous perturbations have not been assessed. This study aimed to quantify the contributions of body segments (ie, trunk, head, upper extremity, and lower extremity) to the control of center-of-mass (COM) movement during continuous, multidirectional, support surface perturbations. Three-dimensional, whole-body kinematics were captured while 10 participants experienced 5 minutes of perturbations. Anteroposterior, mediolateral, and vertical COM position and velocity were calculated using a full-body model and 7 models with reduced numbers of segments, which were compared with the full-body model. With removal of body segments, errors relative to the full-body model increased, while relationship strength decreased. The inclusion of body segments appeared to affect COM measures, particularly COM velocity. Findings suggest that the body segments may provide a means of improving the control of COM motion, primarily its velocity, during continuous, multidirectional perturbations, and constitute a step toward improving our understanding of how the limbs contribute to balance control in moving environments.

scholarly journals Stride-Phase Kinematic Parameters That Predict Peak Elbow Varus Torque

2020 ◽  
Vol 8 (12) ◽  
pp. 232596712096806
Author(s):  
Hiroshi Tanaka ◽  
Toyohiko Hayashi ◽  
Hiroaki Inui ◽  
Tomoyuki Muto ◽  
Kohnan Tsuchiyama ◽  
...  
Keyword(s):  
Center Of Mass ◽  
Knee Extension ◽  
Lower Limbs ◽  
Whole Body ◽  
Kinematic Parameters ◽  
Acceleration Phase ◽  
3 Dimensional ◽  
Dimensional Measurements ◽  
Upward Displacement ◽  
Age Range

Background: During baseball pitching, a high amount of elbow varus torque in the arm cocking-to-acceleration phase is thought to be a biomechanical risk factor for medial elbow pain and injury. The biomechanics of the stride phase may provide preparation for the arm cocking-to-acceleration phase that follows it. Purpose: To determine the kinematic parameters that predict peak elbow varus torque during the stride phase of pitching. Study Design: Descriptive laboratory study. Methods: Participants were 107 high school baseball pitchers (age range, 15-18 years) without shoulder or elbow problems. Whole-body kinematics and kinetics during fastball pitching were analyzed using 3-dimensional measurements from 36 retroreflective markers. A total of 26 kinematic parameters of the upper and lower limbs during the stride phase leading up to the stride foot contact were extracted for multiple regression analysis to assess their combined effect on the magnitude of peak elbow varus torque. Results: Increased wrist extension, elbow pronation, knee flexion on the leading leg, knee extension on the trailing leg at stride foot contact, and upward displacement of the body’s center of mass in the stride phase were significantly correlated with decreased peak elbow varus torque (all P < .05). Moreover, 38% of the variance in peak elbow varus torque was explained by a combination of these 5 significant kinematic variables ( P < .001). Conclusion: We found that 5 kinematic parameters during the stride phase and the combination of these parameters were associated with peak elbow varus torque. The stride phase provides biomechanical preparation for pitching and plays a key role in peak elbow varus torque in subsequent pitching phases. Clinical Relevance: The present data can be used to screen pitching mechanics with motion capture assessment to reduce peak elbow varus torque. Decreased peak elbow varus torque is expected to reduce the risk of elbow medial pain and injury.

Strategies for Dynamic Stability During Locomotion on a Slippery Surface: Effects of Prior Experience and Knowledge

2002 ◽  
Vol 88 (1) ◽  
pp. 339-353 ◽  
Author(s):  
Daniel S. Marigold ◽  
Aftab E. Patla
Keyword(s):  
Dynamic Stability ◽  
Time Course ◽  
Imaging System ◽  
Prior Experience ◽  
Surface Condition ◽  
Center Of Mass ◽  
Whole Body ◽  
Global Changes ◽  
Slippery Surface ◽  
Rate Of Loading

Falls due to slips are prevalent in everyday life. The purpose of this study was to determine the reactive recovery responses used to maintain dynamic stability during an unexpected slip, establish the time course of response adaptation to repeated slip perturbations, and distinguish the proactive strategies for negotiating a slippery surface. Twelve young adults participated in the study in which a slip was generated following foot contact on a set of steel free-wheeling rollers. Surface electromyographic (EMG) data were collected from rectus femoris, biceps femoris, tibialis anterior, and the medial head of gastrocnemius on the perturbed limb. Whole body kinematics were recorded using an optical imaging system: from this the center of mass, foot angle, and medial-lateral stability margins were determined. In addition, braking/loading and accelerating/unloading impulses while in contact with the rollers and the rate of loading the rollers were determined from ground reaction forces. Results demonstrate that the reactive recovery response to the first slip consisted of a rapid onset of a flexor synergy (146–199 ms), a large arm elevation strategy, and a modified swing limb trajectory. With repeated exposure to the slip perturbation, the CNS rapidly adapts within one slip trial through global changes. These changes include the attenuation of muscle response magnitude, reduced braking impulse, landing more flat-footed, and elevating the center of mass. Individuals implement a “surfing strategy” while on the rollers when knowledge of the surface condition was available before hand. Furthermore, knowledge of a slip results in a reduced braking impulse and rate of loading, a shift in medial-lateral center of mass closer to the support limb at foot contact on the rollers and a more flat foot landing. In conclusion, prior experience with the perturbations allows subsequent modification and knowledge of the surface condition results in proactive adjustments to safely traverse the slippery surface.

Force platforms as ergometers

1975 ◽  
Vol 39 (1) ◽  
pp. 174-179 ◽  
Author(s):  
G. A. Cavagna
Keyword(s):  
Body Weight ◽  
Mechanical Energy ◽  
Center Of Mass ◽  
Force Plate ◽  
Vertical Displacement ◽  
The Body ◽  
Mechanical Work ◽  
Vertical Force ◽  
External Work ◽  
Total Mechanical Energy

Walking and running on the level involves external mechanical work, even when speed averaged over a complete stride remains constant. This work must be performed by the muscles to accelerate and/or raise the center of mass of the body during parts of the stride, replacing energy which is lost as the body slows and/or falls during other parts of the stride. External work can be measured with fair approximation by means of a force plate, which records the horizontal and vertical components of the resultant force applied by the body to the ground over a complete stride. The horizontal force and the vertical force minus the body weight are integrated electronically to determine the instantaneous velocity in each plane. These velocities are squared and multiplied by one-half the mass to yield the instantaneous kinetic energy. The change in potential energy is calculated by integrating vertical velocity as a function of time to yield vertical displacement and multiplying this by body weight. The total mechanical energy as a function of time is obtained by adding the instantaneous kinetic and potential energies. The positive external mechanical work is obtained by adding the increments in total mechanical energy over an integral number of strides.

Kinematics and mechanics of ground take-off in the starling Sturnis vulgaris and the quail Coturnix coturnix

2000 ◽  
Vol 203 (4) ◽  
pp. 725-739 ◽  
Author(s):  
K.D. Earls
Keyword(s):  
Body Weight ◽  
High Speed ◽  
Force Plate ◽  
Columba Livia ◽  
The Body ◽  
Whole Body ◽  
Vertical Force ◽  
Wing Movement ◽  
Coturnix Coturnix ◽  
Starting Point

The mechanics of avian take-off are central to hypotheses about flight evolution, but have not been quantified in terms of whole-body movements for any species. In this study, I use a combination of high-speed video analysis and force plate recording to measure the kinematics and mechanics of ground take-off in the European starling Sturnis vulgaris and the European migratory quail Coturnix coturnix. Counter to hypotheses based on the habits and morphology of each species, S. vulgaris and C. coturnix both produce 80–90 % of the velocity of take-off with the hindlimbs. S. vulgaris performs a countermovement jump (peak vertical force four times body weight) followed by wing movement, while C. coturnix performs a squat jump (peak vertical force 7.8 times body weight) with simultaneous wing movement. The wings, while necessary for continuing the movement initiated by the hindlimbs and thereafter supporting the body weight, are not the primary take-off accelerator. Comparison with one other avian species in which take-off kinematics have been recorded (Columba livia) suggests that this could be a common pattern for living birds. Given these data and the fact that running take-offs such as those suggested for an evolving proto-flier are limited to large or highly specialized living taxa, a jumping model of take-off is proposed as a more logical starting point for the evolution of avian powered flight.

scholarly journals Lipolysis and Fat Oxidation Are Not Altered with Presleep Compared with Daytime Casein Protein Intake in Resistance-Trained Women

2019 ◽  
Vol 150 (1) ◽  
pp. 47-54 ◽  
Author(s):  
Brittany R Allman ◽  
Margaret C Morrissey ◽  
Jeong-Su Kim ◽  
Lynn B Panton ◽  
Robert J Contreras ◽  
...  
Keyword(s):  
Body Weight ◽  
Fat Oxidation ◽  
Substrate Utilization ◽  
Whole Body ◽  
Nonesterified Fatty Acids ◽  
Resting Metabolism ◽  
Casein Protein ◽  
Body Resistance ◽  
Subcutaneous Abdominal Adipose Tissue ◽  
Full Body

ABSTRACT Background To date, no studies have directly compared the differences between presleep and daytime protein (PRO) consumption on localized and systemic fat metabolism in active women. Objective The purpose of this study was to assess the effects of presleep compared with daytime PRO supplementation on subcutaneous abdominal adipose tissue (SCAAT) lipolysis and whole-body substrate utilization in women. Methods Thirteen young (mean ± SE age: 22 ± 1 y; BMI: 24.3 ± 0.8 kg/m2), resistance-trained [1 repetition maximum (1RM) squat percentage of body weight: 135% ± 6%; 1RM bench press percentage of body weight: 82% ± 4%] women volunteered. On overnight experimental visits, participants performed full-body resistance exercise (RE; 65% 1RM) and were randomly assigned to consume either daytime PRO (PRO, 30 g casein) 30 min post-RE and presleep (30 min before bed) noncaloric, sensory-matched placebo (PLA, 0 g casein) (PRO-PLA), or the opposite (PLA-PRO), switching the order of the supplements on the following visit. SCAAT lipolysis, resting metabolism (indirect calorimetry), and plasma biomarkers (glucose, insulin, nonesterified fatty acids, glycerol) were measured at baseline, overnight, and the next morning. Results There were no differences in overnight SCAAT lipolysis between conditions indicated by interstitial glycerol concentrations (PRO-PLA: baseline, 669 ± 137; next morning, 321 ± 77.1; PLA-PRO: baseline, 524 ± 109; next morning, 333 ± 68.0 μM), fat oxidation (PRO-PLA: baseline, 5.70 ± 0.35; next morning, 5.00 ± 0.28; PLA-PRO: baseline, 6.59 ± 0.32; next morning, 5.44 ± 0.27 g/min), or any other measure. Conclusions There was no difference between the effects of daytime and presleep PRO supplementation on SCAAT lipolysis or whole-body substrate utilization in resistance-trained women. Presleep PRO is a viable option for increasing PRO consumption in resistance-trained women because it does not blunt overnight lipolysis, and will therefore likely not lead to increases in subcutaneous abdominal fat. This trial was registered at clinicaltrials.gov as NCT03573687.

scholarly journals Test-retest reliability of force plate-derived measures of reactive stepping

2020 ◽  
Author(s):  
Tyler M. Saumur ◽  
Sunita Mathur ◽  
Jacqueline Nestico ◽  
Stephen D. Perry ◽  
George Mochizuki ◽  
...  
Keyword(s):  
Body Weight ◽  
Balance Control ◽  
Intraclass Correlation ◽  
Force Plate ◽  
Correlation Coefficients ◽  
Retest Reliability ◽  
Step Initiation ◽  
Absolute Test ◽  
Test Retest Reliability ◽  
Reactive Stepping

AbstractBackgroundCharacterizing reactive stepping is important to describe the response’s effectiveness. Measures of reactive stepping related to step initiation, execution, and termination phases have been frequently reported to characterize reactive balance control. However, the test-retest reliability of these measures are unknown.Research questionsWhat is the between- and within-session test-retest reliability of various force plate-derived measures of reactive stepping?MethodsNineteen young, healthy adults responded to 6 small (~8-10% of body weight) and 6 large perturbations (~13-15% of body weight) using an anterior lean-and-release system. Tests were conducted on two visits separated by at least two days. Participants were instructed to recover balance in as few steps as possible. Step onset, foot-off, swing, and restabilization times were extracted from force plates. Relative test-retest reliability was determined through intraclass correlation coefficients (ICCs) and 95% confidence intervals (CIs). Absolute test-retest reliability was assessed using the standard error of the measurement (SEM).ResultsFoot-off and swing times had the highest between- and within-session test-retest reliabilities regardless of perturbation size (between-session ICC=0.898–0.942; within-session ICC=0.455–0.753). Conversely, step onset and restabilization time had lower ICCs and wider CIs (between-session ICC=0.495–0.825; within-session ICC=−0.040–0.174). Between-session test-retest reliability was higher (ICC=0.495-0.942) for all measures than within-session test-retest reliability (ICC=−0.040–0.753). SEMs were low (3–10% of mean) for all measures, except time to restabilization (SEM=15-20% of mean), indicating good absolute reliability.SignificanceThese findings suggest multiple baseline sessions are needed for measuring restabilization and step onset times. The SEMs provide an index for measuring meaningful change due to an intervention.

Evaluation of a New Preparation of Urokinase

1973 ◽  
Vol 30 (01) ◽  
pp. 114-122
Author(s):  
C.R.M Prentice ◽  
K.M Rogers ◽  
G.P McNicol
Keyword(s):  
Body Weight ◽  
Maintenance Therapy ◽  
Initial Dose ◽  
Fibrinolytic Activity ◽  
Pharmacological Effect ◽  
Whole Body ◽  
Fibrinolytic Agent ◽  
Thromboplastic Activity

SummaryThe pharmacological effect of a new preparation of urokinase (Leo) has been studied, both in vitro and in six patients suffering from thrombo-embolic disorders. It was a non-toxic, effective fibrinolytic agent if given in sufficient dosage. A regimen consisting of an initial dose of 7,200 ploug units per kg body weight, followed by hourly maintenance therapy with 3,600 ploug units per kg intravenously, gave satisfactory evidence of whole body fibrinolytic activity. The preparation had minor but insignificant thromboplastic activity both when assayed in the laboratory and when given to patients.

scholarly journals Quantitative evaluation and comparison of coronary artery characteristics by 3D coronary volume reconstruction

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yongcheol Kim ◽  
Jonathan James Hyett Bray ◽  
Benjamin Waterhouse ◽  
Alexander Gall ◽  
Georgia May Connolly ◽  
...  
Keyword(s):  
Coronary Artery ◽  
Coronary Angiography ◽  
Coronary Arteries ◽  
Intraclass Correlation ◽  
Quantitative Coronary Angiography ◽  
Volume Estimation ◽  
Diabetic Patients ◽  
Volume Reconstruction ◽  
3 Dimensional ◽  
Inter Observer Variability

AbstractNon-atherosclerotic abnormalities of vessel calibre, aneurysm and ectasia, are challenging to quantify and are often overlooked in qualitative reporting. Utilising a novel 3-dimensional (3D) quantitative coronary angiography (QCA) application, we have evaluated the characteristics of normal, diabetic and aneurysmal or ectatic coronary arteries. We selected 131 individuals under 50 years-of-age, who had undergone coronary angiography for suspected myocardial ischaemia between 1st January 2011 and 31st December 2015, at the Bristol Heart Institute, Bristol, UK. This included 42 patients with angiographically normal coronary arteries, 36 diabetic patients with unobstructed coronaries, and 53 patients with abnormal coronary dilatation (aneurysm and ectasia). A total of 1105 coronary segments were analysed using QAngio XA 3D (Research Edition, Medis medical imaging systems, Leiden, The Netherlands). The combined volume of the major coronary arteries was significantly different between each group (1240 ± 476 mm3 diabetic group, 1646 ± 391 mm3 normal group, and 2072 ± 687 mm3 abnormal group). Moreover, the combined coronary artery volumes correlated with patient body surface area (r = 0.483, p < 0.01). Inter-observer variability was assessed and intraclass correlation coefficient of the total coronary artery volume demonstrated a low variability of 3D QCA (r = 0.996, p < 0.001). Dedicated 3D QCA facilitates reproducible coronary artery volume estimation and allows discrimination of normal and diseased vessels.

scholarly journals Using Biofeedback to Reduce Step Length Asymmetry Impairs Dynamic Balance in People Poststroke

2021 ◽  
pp. 154596832110193
Author(s):  
Sungwoo Park ◽  
Chang Liu ◽  
Natalia Sánchez ◽  
Julie K. Tilson ◽  
Sara J. Mulroy ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Sagittal Plane ◽  
Dynamic Balance ◽  
Objective Measure ◽  
Frontal Plane ◽  
Step Length ◽  
Berg Balance Scale ◽  
Whole Body ◽  
Functional Gait ◽  
Full Body

Background People poststroke often walk with a spatiotemporally asymmetric gait, due in part to sensorimotor impairments in the paretic lower extremity. Although reducing asymmetry is a common objective of rehabilitation, the effects of improving symmetry on balance are yet to be determined. Objective We established the concurrent validity of whole-body angular momentum as a measure of balance, and we determined if reducing step length asymmetry would improve balance by decreasing whole-body angular momentum. Methods We performed clinical balance assessments and measured whole-body angular momentum during walking using a full-body marker set in a sample of 36 people with chronic stroke. We then used a biofeedback-based approach to modify step length asymmetry in a subset of 15 of these individuals who had marked asymmetry and we measured the resulting changes in whole-body angular momentum. Results When participants walked without biofeedback, whole-body angular momentum in the sagittal and frontal plane was negatively correlated with scores on the Berg Balance Scale and Functional Gait Assessment supporting the validity of whole-body angular momentum as an objective measure of dynamic balance. We also observed that when participants walked more symmetrically, their whole-body angular momentum in the sagittal plane increased rather than decreased. Conclusions Voluntary reductions of step length asymmetry in people poststroke resulted in reduced measures of dynamic balance. This is consistent with the idea that after stroke, individuals might have an implicit preference not to deviate from their natural asymmetry while walking because it could compromise their balance. Clinical Trials Number: NCT03916562.

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