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Space Requirements of the Seated Operator

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... There are different methods to estimate the body segment inertial parameters (BSIP) of a given subject [28][29][30][31][32][33][34], including direct measurements on cadavers [35][36][37] or photogrammetry and medical imaging on living humans [38][39][40][41][42][43][44][45][46][47][48]; however, they are more generally estimated by regression and scaling equations (which are derived from such measurements). The inertial properties of the whole body can, then, be computed after defining the subject's posture. ...
... The center of mass was assumed along the longitudinal axis, but no moments of inertia were given (as they were deferred to future studies). This paper updates the results of Reference [35], which are still in use (see, e.g., Reference [33]), combined with those of Reference [58]. ...
... The lengths of body segments were obtained by combining the data of Reference [35,[59][60][61] in Reference [51]. The location of the center of mass of each segment was derived from Reference [35][36][37]62,63], while the inertial properties were derived from Reference [37] (6 male cadavers, average age 54). The number of body segments is 14. ...
Chapter
The work reviews the most common biomechanical datasets (and related prediction/regression formulas) available in the literature and devises a three-dimensional parametric human model suitable for multibody applications. The focus is on bicycle and motorcycle riders. The model presented has been implemented in ADAMS and compared against experiments.
... Body Segment Inertia Parameters (BSIP) and particularly masses of the segments are essential to compute accurate kinetics parameters and provide inverse dynamics process or balance analysis during gait. One of the most common methods to obtain BSIP is to use regression equations obtained from anthropometric analysis of medical imaging, measurements on living subjects or of human cadavers (Dempster 1955;Clauser 1969;Zatsiorsky et al. 1990;Dumas and Wojtusch 2018) based on the total mass of the subjects. ...
... This study aims at comparing the segments' mass distribution of children from 4-to 15-year old between anthropometric tables based on adult's data (Dempster 1955;Clauser 1969;Zatsiorsky et al. 1990;Dumas and Wojtusch 2018) and those based on children data (Jensen 1986) considered as reference. This last anthropometric table only has the specificity to include the age in the regression equations from 4 to 15 years. ...
... Six anthropometric tables were compared in this study. Two studies focused on the BSIP of children with mean age of 4-15 years (Jensen 1986) while four others are based on Caucasian adults with mean age from 23.8 to 68.5-year old (Dempster 1955;Clauser 1969;Zatsiorsky et al. 1990;Dumas and Wojtusch 2018). All of these tables describe masses of the segments. ...
... AnyBody is a multibody dynamics system, which discretizes the body into links representing the bones as rigid segments articulating at the anatomical joints. To each bone was assigned the mass of the other tissues surrounding the bone, such that the sum of segment masses equaled the total body mass and the distribution of masses followed Dempster (Dempster, 1955). ...
... The vertical ground reaction force was calculated in the AnyBody system by the methods described by Fluit et al. (2014) and by Skals et al. (2017). The vertical trajectory of the body center of mass (BCM) was also computed by the AnyBody system using anthropometrics from Dempster (1955). Thus, the vertical stiffness k vert in kN m −1 was calculated by the formula: ...
... However, even body mass 0.66 did not improve the correlations of the present study. It is not straight forward to explain the missing correlation between RE and relative mechanical work rate, but it may be an inherent problem that most biomechanical methods use anthropometric tables, like Dempster (Dempster, 1955), to calculate segmental masses and moments of inertia. This is also the case for the method presented by Winter (1979), which was used in the present study. ...
Article
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Running economy (RE) at a given submaximal running velocity is defined as oxygen consumption per minute per kg body mass. We investigated RE in a group of 12 male elite runners of national class. In addition to RE at 14 and 18 km h−1 we measured the maximal oxygen consumption (VO2max) and anthropometric measures including the moment arm of the Achilles tendon (LAch), shank and foot volumes, and muscular fascicle lengths. A 3‐D biomechanical movement analysis of treadmill running was also conducted. RE was on average 47.8 and 62.3 ml O2 min−1 kg−1 at 14 and 18 km h−1. Maximal difference between the individual athletes was 21% at 18 km h−1. Mechanical work rate was significantly correlated with VO2 measured in L min−1 at both running velocities. However, RE and relative work rate were not significantly correlated. LAch was significantly correlated with RE at 18 km h−1 implying that a short moment arm is advantageous regarding RE. Neither foot volume nor shank volume were significantly correlated to RE. Relative muscle fascicle length of m. soleus was significantly correlated with RE at 18 km h−1. Whole body stiffness and leg stiffness were significantly correlated with LAch indicating that a short moment arm coincided with high stiffness. It is concluded that a short LAch is correlated with RE. Probably, a short LAch allows for storage of a larger amount of elastic energy in the tendon and influences the force–velocity relation toward a lower contraction velocity. Running economy was found to be significantly related to Achilles tendon moment arm, foot length ratio, whole body stiffness and leg stiffness, and muscular fascicle length.
... There are different methods to estimate the body segment inertial parameters (BSIP) of a given subject [28][29][30][31][32][33][34], including direct measurements on cadavers [35][36][37] or photogrammetry and medical imaging on living humans [38][39][40][41][42][43][44][45][46][47][48]; however, they are more generally estimated by regression and scaling equations (which are derived from such measurements). The inertial properties of the whole body can, then, be computed after defining the subject's posture. ...
... The center of mass was assumed along the longitudinal axis, but no moments of inertia were given (as they were deferred to future studies). This paper updates the results of Reference [35], which are still in use (see, e.g., Reference [33]), combined with those of Reference [58]. ...
... The lengths of body segments were obtained by combining the data of Reference [35,[59][60][61] in Reference [51]. The location of the center of mass of each segment was derived from Reference [35][36][37]62,63], while the inertial properties were derived from Reference [37] (6 male cadavers, average age 54). ...
Article
Full-text available
Bicycles and motorcycles are characterized by large rider-to-vehicle mass ratios, thus making estimation of the rider’s inertia especially relevant. The total inertia can be derived from the body segment inertial properties (BSIP) which, in turn, can be obtained from the prediction/regression formulas available in the literature. Therefore, a parametric multibody three-dimensional rider model is devised, where the four most-used BSIP formulas (herein named Dempster, Reynolds-NASA, Zatsiorsky–DeLeva, and McConville–Young–Dumas, after their authors) are implemented. After an experimental comparison, the effects of the main posture parameters (i.e., torso inclination, knee distance, elbow distance, and rider height) are analyzed in three riding conditions (sport, touring, and scooter). It is found that the elbow distance has a minor effect on the location of the center of mass and moments of inertia, while the effect of the knee distance is on the same order magnitude as changing the BSIP data set. Torso inclination and rider height are the most relevant parameters. Tables with the coefficients necessary to populate the three-dimensional rider model with the four data sets considered are given. Typical inertial parameters of the whole rider are also given, as a reference for those not willing to implement the full multibody model.
... Since the second Olympic Games, it started 110m hurdles race and listed as formal competition event in international games [15]. Hurdling can be classified as a very complex technical event that requires high levels of physical fitness [11] In fact, sprint speed, inter-segmental coordination, reactive strength, and great technical skills are the most key physical fitness aspects that should regularly be developed and routinely implemented in training programs to succeed terrace [8]. In particular, the technique of clearing the hurdle represents one of the most determinant elements defining the competitive result [16,21]. ...
... In order to avoid the errors involved in analysis, real measurements were recalculated, taking into account the measurement error, which actually means that they corresponded (e.g., 50 Hz means 0.04 s between frames, so a hurdle clearance time of 0.5 s vs. 0.54 s represents a single frame). In both analyses the model of Dempster [8] was used for the calculation of the body's COM and the kinematic program ARIEL (Ariel Dynamics Inc., Trabuco Canyon, CA, USA) for the digitization was applied. ...
... Dhammika's landing distance was 1.63 m (44.0% of his total stride length), while Robles's was 1.23 m (33.6% of his total stride length). It can be compared with some other studies [8,19], which indicate that the optimal ratio between take-off spot and landing place should be 40-60 %, which is comparable with Amara's [2] findings (i.e., 58:42). This ratio was confirmed by previous researchers [6,7,8,10,19,23], which indicated that take-off distance should range from 2.04 cm to 2.31 cm. ...
Article
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The purpose of the study was to compare the biomechanical parameters of the hurdle clearance technique of the fifth hurdle in the 110 m hurdle race of National Champion (R. Dammika) in Sri Lanka (14.16 s was set in 2019) and D. Robles of Cuba (12.87 s world record was set in 2008). Despite the athletes having performed at different times, we used comparable biomechanical diagnostic technology for both hurdlers. Roshan’s clearance techniques the researchers have settled cameras in order to get the clear views of the hurdles of the 4th and the 5th. Subject performance was recorded with a sample of approximately 100 Hz motion cameras. Robles’s Data were collected by the previous analysis. The results of R. Dhammika’s hurdle clearance was not effective, as it was characterized by a maximal loss of horizontal center of mass (COM) velocity. R. Dhammika completed the hurdle clearance slightly slower, as it took him 0.59 s. Roshan’s take-off phase also lasted 0.13 s, his flight phase 0.37 s, and his landing 0.09 s. Robles’s hurdle clearance took 0.50 s: 0.10 s for the take-off, 0.33 s for the flight phase, and 0.07 s for the landing phase. Dhammika’s Sprint height also included in a lower value under the recommend of COM height. Hurdle clearance landing velocity drop and COM drop Significantly high and Landing phase distance value also higher than stranded value. All the coaches should have to obtain a great knowledge about biomechanical training methods to improve the hurdle technique from minimizing the biomechanical errors.
... where V is the volume of the segments, H is the segment length, R is the radius of the knuckle at the proximal joint, and r is the knuckle at the distal joint. Thus, the segment mass was calculated using the formula segment mass = density (1.1 g/cm 3 ) X segment volume [12]. ...
... The COMs for the proximal and middle segments, and the distal segment were determined by approximating the phalanx with the frustum of a cone and a cylindrical homogeneous rigid body, respectively. The diameters of the knuckles were measured for each participant, and they are assumed to have a uniform density [12]. The COMs of the proximal and middle segments (equation 3) as well as distal segment (equation 4) can be determined by using the following equations. ...
... The anthropometrical mode! used in this study consisted of 16 segments (two feet, two shanks, two thighs, two bands, two forearms, two arms, upper trunk, lower trunk, neck and head). Their definition was based on Dempster's [14]. Liinb segments were separated from each other using horizontal planes going through the joint centres (ankle, knee, wrist and elbow). ...
... According to Jensen's method and using semi-automated software designed at the Université de Valenciennes (France), segments' masses and centre ofmass were computed from sagittal and frontal planes photographs. Body segment parameters computation method relying on the assumption of known segment densities, Drillis and Contini's [15] were used for this study except for the trunk, head and neck segments for which Dempster's [14] were preferred. ...
Thesis
L’utilisation de paramètres inertiels segmentaires proches de la réalité est primordiale à l’obtention de données cinétiques fiables lors de l’analyse du mouvement humain. Le corps humain est modélisé en un nombre variable de solides, considérés indéformables, dans la grande majorité des études du mouvement. Ce travail de recherche a pour but de mettre en œuvre et de tester deux méthodes d’estimation des masses de ces solides appelés segments. Ces deux méthodes sont basées sur le principe d’équilibre statique d’un ensemble de solides rigides. La première a pour objectif la prédiction des masses des membres en se servant des distances parcourues par le centre de masse du membre et le centre de pression, projection horizontale du centre de gravité du sujet, entre deux positions considérées statiques. Le rapport de ces distances étant le même que celui des masses du membre considéré et du corps entier, la connaissance de cette dernière nous permet d’estimer la masse du membre. La seconde méthode a pour but d’estimer simultanément les masses relatives de tous les segments du modèle par résolution de l’équation d’équilibre statique en faisant l’hypothèse que le centre de pression est le barycentre de l’ensemble et d’après l’estimation des positions des centres de masse segmentaires. La démarche expérimentale innovante présentée dans cette thèse consiste en le transfert des centres de masse segmentaires issus d’une méthode anthropométrique géométrique et en leur utilisation en conjonction avec des méthodes usuelles en analyse du mouvement humain afin d’obtenir les masses segmentaires du sujet. La méthode d’estimation des masses des membres donne de bons résultats en comparaison de ceux obtenus grâce aux modèles issus de la littérature en ce qui concerne la prédiction de la position du centre de pression a posteriori. Une partie des causes de l’échec de la seconde sont évaluées à travers l’étude de l’effet de l’incertitude sur la position du centre de pression.
... The coordinates of the Equation (2) depend on the anthropometric parameters that can be measured individually or based on data proposed by Winter and Hof [26][27][28]. The constant distances between points, necessary in further calculations, were determined from the relationship below. ...
... In our model, we did not normalize the joint angles to human height. Dempster has suggested scaling data to a human size to adjust for various participant anthropometrics [28]. We decided to present our results without standardization. ...
Article
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Although it is well-established that exoskeletons as robots attached to the extremities of the human body increase their strength, limited studies presented a computer and mathematical model of a human leg hydraulic exoskeleton based on anthropometric data. This study aimed to examine lower limb joint angles during walking and running by using Inertial Measurement Units. The geometry and kinematic parameters were calculated. Twenty-six healthy adults participated in walking and running experiments. The geometric model of a human leg hydraulic exoskeleton was presented. Joint angle data acquired during experiments were used in the mathematical model. The position and velocity of exoskeleton actuators in each phase of movement were calculated using the MATLAB package (Matlab_R2017b, The MathWorks Company, Novi, MI, USA). The highest velocity of the knee actuator during walking and running was in the swing phase, 0.3 and 0.4 m/s, respectively. For the ankle and hip joints, the highest velocity of actuators occurred during the push-off phase. The results with 26 healthy subjects demonstrated that the system's compliance can be effectively adjusted while guiding the subjects walking in predefined trajectories. The developed mathematical model makes it possible to determine the position of lower limb segments and exoskeleton elements. The proposed model allows for calculating the position of the human leg and actuators' characteristic points.
... Les méthodes mécaniques ex vivo ont permis l'identification des paramètres inertiels grâce à des techniques de suspension et d'oscillation de membres cadavériques (Dempster, 1955;Clauser et al., 1969). Une telle campagne a notamment été menée auprès de l'armée américaine. ...
... Ainsi, des lois de régression ont été conçues pour prédire des mesures en fonction d'autres mesures. La plupart des méthodes de régression anthropométrique ont été basées sur des régressions linéaires ou multi-linéaires pour prédire les paramètres anthropométriques (Dempster, 1955;Drillis et al., 1964), les paramètres inertiels (Dumas et al., 2007;Merrill et al., 2019) ou les volumes musculaires (Handsfield et al., 2014) avec une quantité limitée de données. Ces régressions ont trouvé une application en biomécanique pour mettre à l'échelle des modèles musculo-squelettiques. ...
Thesis
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Le port d’un exosquelette d’assistance à la locomotion permet d’envisager une plus grande mobilité du soldat, de décharger les articulations, de limiter l’apparition de la fatigue musculaire et de limiter la dépense énergétique. En revanche, la conception des exosquelettes d’assistance à la locomotion à des fins militaires est soumise à de fortes contraintes qui rendent le déploiement d’exosquelette difficile. Ainsi, la modélisation musculo-squelettique est envisagée comme un outil pour la conception et l’évaluation afin d'optimiser et de quantifier les bénéfices biomécaniques pour les futurs utilisateurs.Dans cette thèse, on se propose de relever deux défis génériques et spécifiques liés à la modélisation musculo-squelettique. Le premier défi se propose d’identifier des gammes de modèles représentatives de la population et de définir des lois de régression morphologiques génériques pour le soldat. Le deuxième défi consiste à mettre en place des méthodes de personnalisation géométrique et musculaire des modèles musculo-squelettiques. Ces méthodes sont essentielles pour effectuer des simulations musculo-squelettiques cohérentes et pour permettre la conception et l’évaluation des exosquelettes.
... Whole-body center of mass (COM) positions were calculated using segmental position data and published anthropometric data. 32 Synchronized joint kinematic and GRF data (also filtered at a cutoff frequency set at 10 Hz 33 ) were used to estimate 3D net internal ankle, knee, and hip joint torques, using Visual 3D software (C-Motion), the previously mentioned anthropometric data, 32 and a standard inverse dynamics approach. Biomechanical variables of interest included 3D GRF; whole-body COM position; sagittal-and frontal-plane trunk angles; and sagittal-plane hip, knee, and ankle joint angles and net joint internal torques. ...
... Whole-body center of mass (COM) positions were calculated using segmental position data and published anthropometric data. 32 Synchronized joint kinematic and GRF data (also filtered at a cutoff frequency set at 10 Hz 33 ) were used to estimate 3D net internal ankle, knee, and hip joint torques, using Visual 3D software (C-Motion), the previously mentioned anthropometric data, 32 and a standard inverse dynamics approach. Biomechanical variables of interest included 3D GRF; whole-body COM position; sagittal-and frontal-plane trunk angles; and sagittal-plane hip, knee, and ankle joint angles and net joint internal torques. ...
Article
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Context: Patellofemoral pain (PFP) is often categorized by researchers and clinicians using subjective self-reported PFP characteristics; however, this practice might mask important differences in movement biomechanics between PFP patients. Objective: To determine whether biomechanical differences exist during a high-demand multiplanar movement task for PFP patients with similar self-reported PFP characteristics but different quadriceps activation levels. Design: Cross-sectional design. Setting: Biomechanics laboratory. Participants: A total of 15 quadriceps deficient and 15 quadriceps functional (QF) PFP patients with similar self-reported PFP characteristics. Intervention: In total, 5 trials of a high-demand multiplanar land, cut, and jump movement task were performed. Main outcome measures: Biomechanics were compared at each percentile of the ground contact phase of the movement task (α = .05) between the quadriceps deficient and QF groups. Biomechanical variables included (1) whole-body center of mass, trunk, hip, knee, and ankle kinematics; (2) hip, knee, and ankle kinetics; and (3) ground reaction forces. Results: The QF patients exhibited increased ground reaction force, joint torque, and movement, relative to the quadriceps deficient patients. The QF patients exhibited: (1) up to 90, 60, and 35 N more vertical, posterior, and medial ground reaction force at various times of the ground contact phase; (2) up to 4° more knee flexion during ground contact and up to 4° more plantarflexion and hip extension during the latter parts of ground contact; and (3) up to 26, 21, and 48 N·m more plantarflexion, knee extension, and hip extension torque, respectively, at various times of ground contact. Conclusions: PFP patients with similar self-reported PFP characteristics exhibit different movement biomechanics, and these differences depend upon quadriceps activation levels. These differences are important because movement biomechanics affect injury risk and athletic performance. In addition, these biomechanical differences indicate that different therapeutic interventions may be needed for PFP patients with similar self-reported PFP characteristics.
... Other body segment parameters such as mass and moment of inertia can be substantially modified through muscle hypertrophy exercises (i.e., bodybuilding). In most humans the mass of the upper arm segment is about 70% greater than that of the forearm segment [6], and this mass difference is believed to enhance the whip-like coordination in a throwing movement and help produce a high projectile velocity [1], [13]. The present study was inspired by the prospect that performance in throwing sports might be improved through deliberate manipulation of the mass of the athlete's upper arm segment. ...
... The center of the ball and 18 body landmarks that defined a 17-segment model of the participant were digitized in each image, starting from about 10 frames before touchdown of the delivery stride through to when the ball left the field of view of the camera. The segmental data used were those proposed by Dempster [6] for male adults. The two-dimensional coordinates of the ball, the body landmarks, and the participant's center of mass were calculated from the digitized data using the twodimensional direct linear transform (2D-DLT) algorithm. ...
Article
Purpose: The effectiveness of the whip-like coordination in throwing might be influenced by the inertial properties of the athlete's arm. This preliminary study investigated the acute effect of attaching mass to the upper arm on the distance achieved in a modified javelin throw. The aim was to identify the optimum upper arm mass that maximizes throw distance. Methods: Three well-trained adult male athletes performed maximum-effort throws with an 800-g javelin training ball. A wide range of masses (0-1.5 kg) were attached to the upper arm and a 2D video analysis was used to obtain measures of the projection variables for each attached mass. Results: All three athletes showed an effect of attached arm mass on throw distance, and with the optimum mass the athlete's throw distance was increased by 2.2 m, 1.2 m, and 0 m (7%, 4%, and 0%) respectively. The optimum mass was specific to the athlete (0.6 kg, 0.2 kg, and 0 kg) and changes in throw distance were mostly due to changes in release velocity rather than changes in release angle or release height. The experimental results were broadly similar to those obtained using a simple 2D mathematical model of throwing. Conclusions: These results indicate that some javelin throwers might see an increase in throwing performance when a mass is attached to their upper arm. However, the relationship between upper arm mass and throwing performance should be investigated further with studies on more athletes, projectiles of different mass, and other throwing events.
... We wanted to find out to which extent NASA`s experimental data can be represented via mathematical modelling and how much data for an "average" astronaut contrast those for an "average" Bulgarian male. The methods presented in [1]- [5] and the results obtained there give a solid ground for the determination of the geometric and mass-inertial parameters of the HB and therefore we will closely follow the corresponding line of action. ...
... Naturally, all units as well as reference systems used in [1,2,4,5,8,12,13], has been transferred to the ones utilized in the current study. ...
Article
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The aim of the current article is: 1) to present a 20-segmental biomechanical model of the male human body generated within a SolidWorks® environment.; 2) to improve the 16-segmental biomechanical model of the human body described in our previous investigation, shaping the body with 20 instead of 16 segments.; 3) to determine the mass-inertial characteristics of the human body of the average Bulgarian male based on the model.; 3) to verify the proposed 3D CAD model of the human body against the analytical results from our previous investigation, as well as through comparison with data available in the provided reports.; 4) to predict a human body's mass and inertial properties in several body positions as classified by NASA. The comparison performed between our model results and data reported in the literature gives us confidence that this model could be reliably used to calculate these parameters at various postures of the body.
... To understand the basic mechanics of knee joint, sitting position is considered as shown in Figure, where torso and thigh are at rest while distal segment (shank & foot) of lower limbs are free to move along the rotational axis of knee joint. [3][4][5][6][7][8] [9] Parameters that were assumed for calculations ...
... The knee extensor moment arm, i.e. perpendicular distance of patellar tendon is taken as 0.036m and the perpendicular distance of suprapatellar tendon to the centre is given as 0.04m. [2][3][4][5][6][7] [12] ...
Preprint
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The paper is constitutes the designing and analysis of a human Knee Joint, followed by the forces acting on it with respect to two positions taken for reference, namely Extension and Flexion. Calculations were made analytically to correlate the results obtained via Ansys.
... In general, these approaches have strong agreements with more precise techniques. For example, Damavandi [5] stated that body segments parameters obtained from geometrical models used by [8,12,20] had good agreement with force plate method. Furthermore, Durkin [10] reported that BSP of lower leg from [8,12,19] had good agreement with BSP value obtained from dual-energy X-ray absorptiometry (DEXA) scanner. ...
... For example, Damavandi [5] stated that body segments parameters obtained from geometrical models used by [8,12,20] had good agreement with force plate method. Furthermore, Durkin [10] reported that BSP of lower leg from [8,12,19] had good agreement with BSP value obtained from dual-energy X-ray absorptiometry (DEXA) scanner. ...
Article
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Body segment parameters are required as input parameters to analyze the forces and moments acting on the joints. They can be used to design the farm tools, protective clothing, equipment, and workplaces. The study was planned to develop geometric models for female agricultural workers of Central India. Anthropometric data of 180 female agricultural workers aged between 25 and 45 years having weight of 45.74 ± (7.56) kg and height of 1510 ± (50) mm were collected to develop 14-segmental 3D geometrical models. The values of mean, maximum, minimum, standard deviation (SD) and 5th and 95th percentile anthropometric dimension were calculated. Based on geometric models, mass, density, volume, center of mass (COM) and moments of inertia of body segments were calculated. To test the validity of the model with other models for body segment parameters, an analysis was carried out using SAS 9.3 software with one-way analysis of variance. There was a significant difference (p < 0.01) between the study model and other models based on Dunnett's multiple comparisons post hoc test. From post hoc test analysis, it was observed that developed 14 segments geometric model can be used to determine body segment parameters (BSPs), i.e., segment mass, volume, center of mass (COM) and radius of gyration (RG).
... Eighteen anatomical points of the body were manually digitized in each recorded video field. The coordinates of the body center of mass (BCM) were calculated for every field using the anatomical data provided by Dempster (1955). A second-order low-pass Butterworth filter with a cut-off frequency of 6 Hz was selected for smoothing. ...
Conference Paper
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The purpose of the present study was to assess hurdle kinematics of young athletes when clearing the first two hurdles (0.76 m height) of a simulated hurdle race. Participants run the distance from the starting line to the 2 nd hurdle. All trials were video recorded in order to evaluate specific kinematic variables related to hurdle clearance motion. Results revealed that young athletes negotiate the hurdles with lower values of horizontal velocity and hurdle clearance distance parameters, and tend to adopt "a jumping action" over the hurdle compared to the motor pattern of more skilled hurdlers. Horizontal velocity variation affected the technical model of hurdle clearance at the 2 nd hurdle, compared to the 1 st hurdle, forcing young participants to clear the 2 nd hurdle with higher vertical displacement.
... 204 -----------------------~Chapitre 5-Perspectives de recherches Une première piste vise à affecter un volume à chaque solide constituant la structure cinématique de notre modèle. Le paramétrage de ces volumes peut être tiré par exemple des travaux menés par Dempster (Dempster, 1955), par Zatsiorsky et Seluyanov (Zatsiorsky et Seluyanov, 1983 proposées afin que la simulation produise un mouvement plus représentatif du mouvement réellement réalisé par le sujet (Cf. § 5.2). ...
Thesis
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La difficulté éprouvée pour monter ou descendre d’un véhicule automobile peut amener les personnes âgées et/ou ayants des déficiences motrices à ne plus utiliser leur véhicule. Les constructeurs automobiles l’ont compris et s’intéressent aujourd’hui à ces populations vieillissantes et/ou déficientes sujettes à des troubles de l’appareil locomoteur ainsi qu’à ce geste complexe nécessitant une coordination précise des mouvements articulaires du corps humain. Une alternative pour comprendre et prévoir ce mouvement est d’utiliser la simulation numérique. Les travaux réalisés s’inscrivent dans ce contexte et portent sur la simulation cinématique du mouvement d’entrée d’un humanoïde de synthèse (constitué d’une tête, d’un tronc, d’un bassin et des membres inférieurs) dans des véhicules de dimensions variables à partir de données réelles issues de l’expérimentation. Pour résoudre ce problème « complexe », nous proposons une démarche méthodologique en trois étapes. Une première étape porte sur la constitution d’une base de mouvements dits « exploitables » issues de l’expérimentation menée sur deux véhicules de géométrie distinctes. Ces mouvements « exploitables » sont le résultat de traitements numériques appliqués aux mouvements d’entrée mesurés. Ces traitements permettent, entre autres, d’adapter les angles articulaires mesurés à l’humanoïde de synthèse retenu afin d’éviter d’éventuelles collisions avec l’habitacle qui n’auraient pas été constatées lors des expérimentations. Une deuxième étape porte sur l’analyse et l’identification de manière automatique des stratégies d’entrée dans un véhicule automobile. Cette étape procède en quatre phases à l’issu desquelles 2 stratégies ainsi que 6 sous stratégies du mouvement d’entrée sont identifiées. Une troisième étape, constituée de 4 phases également, utilise les acquis issus des étapes 1 et 2 pour simuler un mouvement d’entrée d’un sujet de la base adoptant une sous stratégie donnée dans un véhicule de géométrie différente. La simulation du mouvement d’entrée d’un même sujet dans un autre véhicule relève d’un problème de cinématique inverse résolu par une programmation non linéaire avec contraintes. Des simulations, impliquant des personnes âgées et/ou ayants des prothèses, permettent de valider la démarche proposée pour les deux stratégies d’entrée. Malgré les différences avec les mouvements mesurés, les mouvements simulés sont conformes aux sous stratégies adoptées par les sujets lors des expérimentations. De plus, les simulations réalisées permettent d’expliquer en partie les changements de stratégie opérés par certains sujets, lors des expérimentations, suite au changement de véhicule automobile. Enfin, des simulations sur des véhicules fictifs montrent les limites de l’outil de simulation développé.Ce travail ouvre plusieurs perspectives de recherches tant concernant l’amélioration de la simulation, en considérant par exemple les différences intra- individuelles des sujets ou encore la dynamique du mouvement, que l’élaboration de nouveaux indices ergonomiques afin d’estimer l’inconfort associé aux mouvements simulés.
... Eighteen anatomical points of the body were manually digitized in each recorded video field. The coordinates of the body center of mass (BCM) were calculated for every field using anatomical data provided by Dempster (1955) and prosthesis center of mass characteristics that were measured using the method described by Clauser et al. (1963). A second-order low-pass Butterworth filter (cut-off frequency: 6 Hz) was selected for smoothing. ...
Conference Paper
Full-text available
This study aimed to investigate approach run kinematics using an upper limb prosthesis. A European Τ47 long-and triple-jump champion with right upper-limb congenital deficiency was analyzed in simulated approach run-ups wearing prosthesis (PW) or not (NP). Two attempts in each condition were recorded (300 fps). Step characteristics and kinematic parameters were extracted for the deficient (DLS) and intact (HLS) sides with a 2D-DLT analysis during the early (EA) and late (LA) approach. Results revealed systematic asymmetry for step frequency and length in NP, with the latter reduced in PW. Horizontal velocity in both EA and LA was larger by 0.3 m/s in PW than NP. These results suggest that asymmetry of NP reduces approach run performance compared to PW.
... Regarding the SpJH, the total body CoM was computed by applying a regression formulation on the segment positions (Dempster, 1955), and the SpJH was calculated by subtracting the maximum CoM height from the standing position CoM in a vertical direction. The average of six SpJHs was further used in statistical analysis. ...
Article
Force-time (F-T) characteristics of countermovement jump (CMJ) are globally referenced as the main descriptors of athletic jump performance, particularly for volleyball players. Nevertheless, it is still unclear to what extent the vertical jump performance during testing is associated with jump performance during game-like conditions. This study was designed to investigate the association between F‑T curve variables derived from CMJ, including movement timings, force, velocity, power, rate of force development (RFD), modified reactive strength index (RSImod), and net impulse with spike jump height during game-like circumstances. Thirteen young elite volleyball players performed three CMJs and six spike jumps in game-like circumstances. Pearson’s product correlation test portrayed a significant correlation between spike jump height and peak RFD (r = 0.75), average RFD (r = 0.76), RSImod (r = 0.56), and concentric net impulse (r = 0.61). Multiple regression analysis also showed that these factors have a strong contribution for predicting spike jump heights (71%). The findings of this study emphasise the importance of RFD, concentric net impulse, and RSImod values in the precise analysis and prediction of volleyball attackers’ spike jump height during game-like conditions.
... Thus, regression models have been designed to predict measurements as functions of other ones. Most anthropometric regression methods have been based on linear or multiple regression models to predict anthropometrics [1], [2], inertial parameters [3], [4] or muscle volumes [5] with a limited amount of data. These regressions have found an application in biomechanics to scale musculoskeletal (MSK) models. ...
Chapter
Full-text available
Collecting anthropometric data is a heavy and time-consuming procedure. The aim of this study was to find a reduced set of anthropometric measurements able to estimate the full-body dimensions of a given individual. The method was developed and applied on a database of 122 measurements carried out on 459 females and 771 males of the French military personnel. Among the 122, 26 key measurements were chosen. A regression method based on support vector machine was used to predict these key measurements in relation to each other. The designed “minimal measurement set selecting algorithm” chose 6 main inputs to predict the remained 20 measurements with mean correlation of 0.94 and 0.92, respectively on the training and on the testing data. This result tends to prove that the regression method can be used to predict the French military personnel anthropometrics.
... Model pose was reconstructed using inverse kinematics [24]. Body segment masses and moments of inertia were scaled according to Dempster [25] and Hanavan [26], respectively. External joint moments were calculated at the knee using a recursive Newton-Euler method [27]. ...
Article
The aim of this study was to investigate if the distribution of subchondral volumetric bone mineral density (vBMD) from peripheral quantitative computed tomography (pQCT) is related to estimates of knee joint loads calculated during walking gait in healthy young people. We recruited 19 young (age 18-40 years) healthy people with no self-reported knee pain or pathology. For all participants we collected two forms of data: (1) pQCT data at 2% of tibia length (from the proximal joint line) using a Stratec XCT3000 scanner at 0.2×0.2 mm in plane resolution; and (2) indices of joint loading, specifically external joint moment, at the indexed knee during walking gait. Joint moments were calculated from motion capture and ground reaction force data. pQCT scans were performed immediately prior to gait analysis. A sub-group of 9 participants attended a second scanning session to establish the reproducibility of the pQCT workflow. vBMD was extracted for four sub-regions (anteromedial, anterolateral, posteromedial and posterolateral). Reproducibility of the pQCT workflow was good to excellent (ICCs 0.832-0.985) with minimal detectable differences ranging from 2.3-39.5 mg HA/cm3. Significant independent correlations were identified between the external rotation moment and the medial-to-lateral (r=0.517), posteromedial-to-posterolateral (r=0.627) and posteromedial-to-anterolateral (r=0.518) vBMD ratios, and between the knee adduction moment and the medial-to-lateral (r=-0.476) and posteromedial-to-posterolateral (r=-0.497) vBMD ratios. There appear to be significant relationships between measures of vBMD from pQCT and indices of joint loading in healthy people. These data are the first to combine imaging at the resolution available with pQCT and indices of joint loading in the same cohort.
... To determine the actual tissue masses specific to the head, neck, trunk, and pelvis, the DXA scans were analyzed using en-CORE TM software (2013, GE Healthcare, v. 15.00.362) by creating custom regions of interest (ROIs) for each segment. The regional borders dividing the extremities from the core segments were made consistent with previously reported research (Holmes et al., 2005;Burkhart et al., 2009;Gyemi et al., 2017), in which specific anatomical landmarks and techniques (Dempster, 1955;Clarys, Martin, & Drinkwater, 1984) were used to minimize tissue misattribution in the frontal plane between the lower extremities and pelvis, and upper extremities and trunk, respectively. Similarly, distinct anatomical landmarks were also utilized to help establish regional borders between the core segments (head and neck: the curvature of the inferior edge of the mandible; neck and trunk: the superior aspects of the clavicles; trunk and pelvis: the superior aspects of the iliac crests). ...
Article
Full-text available
Background: Regression equations using anthropometric measurements to predict soft (fat mass [FM], lean mass [LM], wobbling mass [WM]) and rigid (bone mineral content [BMC]) tissue masses of the extremities and core body segments have been developed for younger adults (16-35 years), but not older adults (36-65 years). Tissue mass estimates such as these would facilitate biomechanical modeling and analyses of older adults following fall or collision-related impacts that might occur during sport and recreational activities. Purpose: The purpose of this study was to expand on the previously established tissue mass prediction equations of the head, neck, trunk, and pelvis for healthy, younger adults by generating a comparable set of equations for an older adult population. Methods: A generation sample (38 males, 38 females) was used to create head, neck, trunk, and pelvis tissue mass prediction equations via multiple linear stepwise regression. A validation sample (13 males, 12 females) was used to assess equation accuracy; actual tissue masses were acquired from manually segmented full body Dual-Energy X-ray Absorptiometry scans. Results: Adjusted R2 values for the prediction equations ranged from 0.326 to 0.949, where BMC equations showed the lowest explained variances overall. Mean relative errors between actual and predicted masses ranged from –2.6% to 6.1% for trunk LM and FM, respectively. All actual tissue masses except head BMC (R2 = 0.092) were significantly correlated to those predicted from the equations (R2 = 0.403 to 0.963). Conclusion: This research provides a simple and effective method for predicting head, neck, trunk, and pelvis tissue masses in older adults that can be incorporated into biomechanical models for analyzing sport and recreational activities. Future work with this population should aim to improve core segment BMC predictions and develop equations for the extremities.
... Previous immersion methods of measuring the volume changes in extremities have relied on one of two principles. In its simplest form volume displacement consists of placing an extremity into a tank full of water and measuring the overflow (Dempster 1955). This system has two disadvantages: ...
Article
A new system for measuring the cross-sectional area profiles of amputation stumps and whole limbs has been designed at the Amputee Research Centre. The instrument consists of a cylindrical tank supported on an elevator. The tank is raised to the height of the amputation stump and filled with water. A graph of the cross-sectional area profile of the amputation stump is generated by a mini-computer as the elevator descends. The cross-sectional area (A) is calculated from the expression: where Hw = height of water in the tank This paper describes the instrument, which may find application in many other areas where there is a need to study shape.
... We can categorize these methods into six categories. The first method is to predict the mass of each segment as ratio of the total mass of the cadaver [40] [41] [42], but this technique is not suitable for our research, because it can't describe neither the center of gravity location nor the moments of inertia. ...
Thesis
Abstract: The objective of this work is to build a testing machine for prosthesis. The machine should be able to reproduce the same dynamic and kinematics conditions applied on the prosthesis during the normal use. Numbers of amputation and causes of amputation were collected. Different types of prosthesis were classified according to the leg prosthesis per amputation height, passive and active prosthesis, differentiated by the nature of their actuator. Most of the testing machine for the prosthesis were studied form the technological and capability prospective. Determining all the limitations of most of existing testing machines, and the needs to develop a new machine to full fill these needs were developed. Then we studied and analyzed the dynamics of the human gait and run. The equations of motion by taking into consideration the masses and moments of inertia of skeletal segments. Most of the parameters of gait were extracted. In conclusion, we have the kinematic requirements of the human center of gravity to generate 6 DOF that the testing machine should carry out to emulate the normal human gait and run. Three designs were proposed to implement the testing machine; Articulated robot arm, Cartesian manipulator, and Stewart Platform (SP). After implementing the three solutions we found the most suitable solution is the SP attached with it an artificial active hip. We have chosen the hydraulic power as it is the most suitable actuation technique for our solution knowing the required actuation forces. To help in controlling the SP motion, a novel Closed-form solution of direct Geometric model for planer and 6-6 Stewart Platform using the rotary sensors instead of liner sensors as wanted to the hydraulic actuators was developed. Sensitivity analysis was studied for that solution, and analytical calculation for computing the workspace was also developed. The conclusion from this testing machine is that we can create all the dynamics of the human body, i.e. walking or running or going up and down stairs. The developed solution can carry testing procedures for either passive or active prothesis
... Twenty-two anatomical points of the body (top of the head, neck, shoulder, elbow, wrist, tip of the fingers, hip, knee, ankle, heel, metatarsals, tip of the toe, on both sides of the body) were manually digitized in each recorded field. The coordinates of the body center of mass (BCM) were calculated for every field using the anatomical data suggested by Dempster (1955). Smoothing of the raw data was accomplished with a second-order low-pass Butterworth filter (cut-off frequency: 6 Hz). ...
Article
Full-text available
The purpose of the present study was to present a report of the biomechanical analysis of the winner of the Women's Long Jump in the 2017 European Indoor Championships held in Belgrade, Serbia. All attempts of the examined jumper (age: 26.8 years; height: 1.76 m; mass: 65 kg), who won the competition with an official distance of 7.24 m, were recorded with a high-speed video camera operating at a sampling frequency of 300 fps. The kinematical parameters of the final steps of the approach and the takeoff were calculated using with a panning analysis method. Results revealed that the best jump was accomplished with the highest individual value for vertical takeoff velocity (2.94 m/s). The less variable parameter of the approach was the horizontal velocity (9.6±0.1 m/s), while the most variable parameter was the contact/flight time ratio for the last step (0.65±0.09). An inter-limb difference was observed for step frequency in the final steps. For the best jump, the examined athlete had an exact coincidence at the final step of the adjustment needed and the adjustment made in order to optimize the foot placement on the board. The examined jumper's biomechanical parameters were in accordance with reports about her technique analyzed in major international competitions. The findings of the present report are in agreement with previous research concerning the importance of vertical takeoff velocity, the accuracy of foot placement on the board and the observed reliance and asymmetries in the step parameters of the final approach.
... Visual3D calculates the CoM via segment positions and regression equations. 17 The sagittal change of angle between adjacent segments presents the extension in knees, hips, and shoulders (knee: shank-thigh; hip: thigh-torso; and shoulder: upper arm-torso). ...
Purpose: To determine the effect of in-season differential training on volleyball spike-jump technique and performance in elite-level female players. Methods: During the season, spike jumps of 12 elite female players (Austrian Volleyball League Women) were recorded by 13 Qualisys Oqus cameras (250 Hz) and an AMTI force plate (1000 Hz). First measurement was made at the beginning of the investigation. Two identical measurements were repeated after a first and a second interval. The first interval served as control phase. The second interval was comparable in length and regular program but included differential training (6 wk, 8 sessions of 15-20 min) as a modified warm-up. It addressed specific performance determinants. Analyses of variances were calculated for the 3 measurements and for the development during control and intervention phase. Results: Initial jump height (0.44 [0.09] m) changed by -4.5% during the control phase and +11.9% during the intervention (P < .001, ηp2=.70). All approach variables, arm backswing, and velocity-conversion strategy improved compared with the control phase (Δ%: 6.1-51.2%, P < .05, ηp2=.40-.80). Joint angles, countermovement depth, maximal angular velocities, and torso incline were not affected (Δ%: -2.9-9.1%, P = .066-.969, ηp2=.00-.27). Conclusions: In-season differential training led to technical adaptations and increased spike-jump height in elite female players. The differential training program allowed players to experience a range of adaptability and to adjust toward an individual optimum in technical components of performance determinants. Coaches are encouraged to apply technical differential training to elite athletes and to target biomechanical performance factors specifically.
... The direct measurement includes balance board test, water immersion, 16 pendulum technique 17 and cadaver method. [18][19][20][21][22][23] The indirect calculation method is usually based on the regression equations established by anthropometric statistical studies using imaging technology such as gamma ray scanning, magnetic resonance imaging (MRI), computed tomography (CT) and dual energy X-ray absorptiometry (DEXA). 3,16 However, the indirect calculation method is currently used for nonamputated people. ...
Article
Quantification of segment-inertial uniqueness can provide a relevant foundation for motion analysis, biomechanical modeling and human motor skill optimization of both normal and amputated athletes. It is known that previous studies focused on quantifying Body Segment Inertial Parameters (BSIP) of non-amputated people in order to establish regression equations for calculating BSIPs. Until now, no anthropometrical study existed on quantifying BSIPs such as mass and center of mass (COM) of both non-amputated segment (NAS) and partially-amputated segment (PAS) of amputees. This study aims to fill the gap. A quantification method derived from Damavandi approach was applied to determine the mass and COM of PAS as well as full-body COM. For validating the reliability of this method, the calculated values were compared to the values measured by balance board test. Further, two anthropometrical approaches (i.e. Zheng and Zatsiorsky) for normal subjects were tested for their validity to estimatfe the mass and COM of NASs of amputees. The results reveal that Damavandi approach can also be used for reliable quantifying of mass and COM of PAS and Zatsiorsky’s approach is more reliable to quantify NAS masses and full-body COM of amputees, therefore, Damavandi approach and Zatsiorsky’s regression model are more suitable for motion analysis, biomechanical modeling and motor skill optimization of amputees.
... After cutting each body segment out of the whole mesh, the moments of inertia (MoI) and the center of mass (CoM) of each segment were calculated using MeshLab (Cignoni et al., 2008). The three submodels were calculated multiplying the volume and MoI with the following density measurements: 1.) the density of ρ = 1 g/cm 3 (IMρ = 1); 2.) the density measurements from Chandler (1975) (IMCH), 3.) Dempster's (1955) (IMD), density measurements. Afterwards the maximum net joint moments for the following movements were calculated: shoulder internal rotation, shoulder horizontal flexion, shoulder abduction, elbow flexion, elbow varus and wrist palmar flexion. ...
Conference Paper
Full-text available
The calculation of inverse dynamics (ID) solutions is widely used to examine potential injury risks and sources for performance enhancement. The results of these calculations are influenced, among others, by the chosen set of body segment inertia parameters (BSIP). While throwing movements are frequently analyzed via ID and there exists a broad variety of BSIP models, the influence of the BSIP sets on the outcome is not well examined. Therefore, the aim of this study was to clarify the influence of different BSIP sets on the modelling results in javelin throwing. For this purpose the kinematics of ten male javelin throwers were recorded. Six available models were used to estimate the BSIP values of the upper limp for each thrower. The chosen BSIP model had large influence on the derived BSIP parameters which showed variations between 8% and 120%. Also, the maximum net joint moment varied between 6% and 21%. Hence, our study suggests that for modelling joint kinetics in throwing movements the model should be chosen carefully.
... Whole body three-dimensional kinematics were captured using thirty-nine passive retro-reflective markers attached to participants' bodies as in the Vicon Plug-in Gait full body model, and recorded using an eight camera Bonita motion capture system (Vicon, Oxford, U.K) sampling at 200 Hz. This allowed for the quantification of arm kinematics and future determination of CoM displacement (for which the Plug-in Gait model uses the Dempster (1955) method to estimate CoM position). Muscle activity for representative muscles of the limbs and trunk segments were recorded using a MA-300 12channel surface electromyography (sEMG) system (Motion Lab Systems, Baton Rouge, LA) and 4-channel Bagnoli (Delsys, Natick, MA) sEMG system sampling at 1,000 Hz. ...
Article
Postural and movement components must be coordinated without significant disturbance to balance when reaching from a standing position. Traditional theories propose that muscle activity prior to movement onset create the mechanics to counteract the internal torques generated by the future limb movement, reducing possible instability via centre of mass (CoM) displacement. However, during goal-directed reach movements executed on a fixed base of support (BoS), preparatory postural activity (or pPAs) promote movement of the CoM within the BoS. Considering this dichotomy, the current study investigated if pPAs constitute part of a whole-body strategy that is tied to the efficient execution of movement, rather than the constraints of balance. We reasoned that if pPAs were tied primarily to balance control, they would modulate as a function of perceived instability. Alternatively, if tied to dynamics necessary for movement initiation, they would remain unchanged, with feedback-based changes being sufficient to retain balance following volitional arm movement. Participants executed beyond-arm reaching movements in four different postural configurations that altered the quality of the BoS. Quantification of these changes to stability did not drastically alter the tuning or timing of preparatory muscle activity despite modifications to arm and CoM trajectories necessary to complete the reaching movement. In contrast to traditional views, preparatory postural muscle activity is not always tuned for balance maintenance or even as a calculation of upcoming instability but may reflect a requirement of voluntary movement towards a pre-defined location.
... BSIP were computed from the body, including the residual limb shape contour reconstructed using EOS radiographs (Nérot et al., 2015) and segmented according to Dumas et al.(Dumas et al., 2007) The mass of the socket was added to one of the residual limbs. Densities were taken from Dempster, (Dempster, 1955) except for the thorax, where a modified density taken from (Amabile et al., 2016) was used. The prosthetic foot and knee "(prosthetic shank mass being neglected compared to the mass of the knee prosthetic component)" were considered as point masses located at their centre of mass. ...
Article
Background Body Center Of Mass velocity assessment is a prerequisite for several applications in prosthetic control and rehabilitation monitoring. Force plate data integration is a promising alternative to full-body quantitative analysis of segmental kinematics to estimate the velocity. Still, it remains to be implemented and validated for people with transfemoral amputation. Methods Two methods were used (force plate based and pelvic markers based) for Body Center Of Mass velocity estimation in a clinical context. The two methods were comparatively assessed on overground walking data of eight people with transfemoral amputation in a laboratory equipped with a motion capture system and force plates compared to reference estimation derived from a full body segmental gait analysis. The ‘Methods’ agreement with the reference was quantified from the Bland and Altman procedure. Findings The estimation of Body Center Of Mass velocity from force plate data integration was considered acceptable in terms of limits of agreement. In addition, the hypotheses used to determine integration constants were evaluated and shown to be reasonable as far as the walking direction is well controlled. Interpretation Results demonstrate the possibility to use the force plate method to assess the Body Center Of Mass velocity of people with transfemoral amputation for straight walking on level ground. An estimation from the velocity of pelvic markers can also be a relevant alternative as soon as the walking velocity remains low. Further investigation will deal with the impact of the errors on the computation of derived parameters such as individual limb power.
... The model was based on the segmental weight distributions acting above or rotating about the hip joint(s) in SL and DL squat or jump movements. Segmental data of Dempster (1955) indicates that the combined body weight (BW) acting above the hips in a DL movement is 68%, that acting about the hip in a SL movement is 84% (see Figure 1). Assuming an equal load distribution between limbs in a DL movement, the SL movement equates to 1.62 times the intensity in one leg of the DL movement. ...
Poster
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PURPOSE When comparing or prescribing loads for single leg (SL) squat or jump movements there is a tendency to assume that the load will be half of what an athlete performs in the double leg (DL) movement. Whilst this is a reasonable starting point, the reality is that the SL movement is more challenging and we cannot make this assumption. AIMS The aims of this study were to develop a theoretical model to determine the load ratio between SL and DL movements and to compare against actual force data in SL and DL Countermovement Jumps (CMJ's). METHOD The model was based on the segmental weight distributions acting above or rotating about the hip joint(s) in SL and DL squat or jump movements. Segmental data of Dempster (1955) indicates that the combined body weight (BW) acting above the hips in a DL movement is 68%, that acting about the hip in a SL movement is 84% (see Figure 1). Figure 1. Segmental weight distribution acting above or about the hip joints in DL and SL movements We can therefore estimate SL forces on the basis of the following equation: SL FORCE = 0.81 x DL FORCE (equation 1), where (68/84 = 0.81). To test this model five male athletes (age 16 ±1 year, body mass 65.6 ±9.2kg) were tested performing DL and SL CMJ's on a Kistler force platform (type 9287B) at 1000 Hz. Peak Forces were collected over three trials and the average taken for each athlete.
... Each segment density was assumed to be uniform. The optimal density set of the 14 segments for each subject was selected from the 26 density sets of cadavers (Dempster, 1955;Chandler et al., 1975). Subsequently, the density of each segment was adjusted in such a way that the sum of products of the calculated volume and the optimal density for each segment corresponds to the whole body mass. ...
... The camera images were manually digitised to apply the elliptical zone method 26 to obtain personalised body segment parameter data. The mass, volume, CM location, and moments of inertia of each segment were obtained using the digitised data and segmental density data reported in Dempster 27 using the 'E-Zone' software 28,29 . ...
Article
Full-text available
The current study investigated body roll amplitude and timing of its peak in backstroke and compared them with front crawl swimming. Nineteen anatomical landmarks were digitised using 80 swimming trial videos (ten swimmers × two techniques × four intensities) recorded by two above-and four below-water cameras. One upper-limb cycle was analysed for each trial, and shoulder and hip roll, whole-body roll (WBR), and WBR due to the buoyant torque (WBR BT) were obtained. Main effects of intensity and technique on the amplitude and timing to reach the peak in those variables were assessed by two-way repeated-measures ANOVA. Swimmers decreased their WBR BT amplitude with an increase in the intensity in both techniques (p ≤ 0.005). The same result was observed for the amplitude of WBR, shoulder roll, and hip roll only in front crawl (p ≤ 0.017). Swimmers maintained the timing of peak WBR BT in both techniques, while they shifted the timing of WBR and hip roll peak toward the beginning of the cycle when increasing the intensity in front crawl (p ≤ 0.017). In conclusion, swimmers maintain the amplitude of WBR, shoulder roll, and hip roll in backstroke when the intensity increases, whereas they reduce the amplitude of all rolls in front crawl.
... Inverse dynamics was then used to calculate joint moments normalised to body mass, which were described as external moments in this study (e.g., an external knee abduction moment will tend to put the knee in abduction). The mass of each segment was calculated based on the proportions of Dempster (Dempster, 1955). The angle and moment data were then filtered with a fourth-order bidirectional low-pass Butterworth digital filter with a cut-off frequency of 15 Hz. ...
Article
Full-text available
We compared knee landing mechanics with presumed relation to risk of anterior cruciate ligament (ACL) injury among three single-leg hop tests and between legs in individuals with unilateral ACL reconstruction. Thirty-four participants (>10 months' post-surgery, 23 females) performed the standardised rebound side hop (SRSH), maximal hop for distance (OLHD) and maximal vertical hop (OLVH). We calculated the following knee outcomes from motion capture and force plate data: finite helical axis inclination angles (approximates knee robustness), frontal and transversal plane angles at initial contact, peak angles of abduction and internal rotation during landing, and peak external moments of flexion, abduction and internal rotation during landing. Repeated-measures MANOVA analysis ('sex' as covariate) confirmed that SRSH induced greater angles and moments, particularly in the frontal plane, compared to OLHD and OLVH. There was between-leg asymmetry for peak knee flexion moment for males during OLHD and OLVH, and for females during SRSH. Our results advocate the SRSH over OLHD and OLVH for assessment of knee landing control to screen for movement patterns potentially related to ACL injury risk. However, clear differences in both knee kinematics and kinetics between OLHD and SRSH motivate the use of both tests to evaluate different aspects of landing control.
... The upper surface of the platforms was covered with a commercial-grade sandpaper (100-grit) to provide sufficient coefficient of friction. A 3-D motion analysis system (QTM, Sweden) was used to build a 13-segment model, reconstructed from a 20 marker setup based on the anthropometric model data (Dempster, 1955). By applying the appropriate weighting factors of these segmental masses, the CoM location was estimated (Winter, 2009). ...
Article
The multi-joint coordination responsible for maintaining upright posture in the standing human manifests in the pattern of variation of the support-surface force (F). Assessment of both the translational and rotational kinematics in the sagittal-plane requires understanding the critical relationship between the direction and location of F. Prior work demonstrated that band-pass filtered F direction and center-of-pressure (CoP) covary in time such that the F vector lines-of-action pass near a fixed point called an intersection point (IP). The height of that IP (IPz) varies systematically with the frequency of the pass band. From F measurements in able-bodied humans (n =17) standing on various pitched surfaces, the present study also found the emergent property of an IP, with IPz located above the center of mass (CoM) at frequencies <1.75 Hz and below the CoM for higher frequencies. This property aids in maintaining upright posture for various perturbation modes within a single control structure. From purely mechanical effects, standing on a pitched surface should not change IPz, however these measurements of F show that IPz is generally closer to CoM height. This characterization of quiet standing provides simple means of assessing the complex multi-joint coordination of standing and relates directly to the physical demands of controlling the translational and rotational aspects of body posture.
... Joint angles were defined as shown in Fig. 2. Centers of gravity and moments of inertia of each segment were defined by modeling the segments as geometric solids (Hanavan, 1964). Segment masses were defined based on the values published by (Dempster, 1955). All jump-landing joint kinematics and kinetics were calculated for the ankle, knee and hip joint of the right limb assuming symmetry between both legs during jump-landing. ...
Article
Loaded jumps are commonly used to improve leg muscle power. However, the additional load during jump-landing might increase the potential for overuse injury. Therefore, the aims of this study were to evaluate the effect that barbell load has on lower limb joint kinematics and kinetics during jump-landing and to evaluate the effect of arresting the barbell load at flight apex prior to landing on joint kinematic and kinetic variables. Barbell-loaded squat jumps (20, 40, and 60 kg) were investigated during two jump-landing conditions: 1) barbell-loaded (landing with barbell load) and 2) barbell-arrested (barbell load arrested at flight apex prior to jump-landing). Lower body kinematics and joint kinetics were assessed during jump-landing. In the barbell-loaded jump-landing condition, joint angles at initial contact decreased with increasing barbell load. Knee and hip peak power decreased (knee: -38%; hip: -46%), while ankle joint work increased with increasing barbell load. Joint moments, powers and work were decreased in the barbell-arrested condition compared to the barbell-loaded condition. Barbell-loaded jump-landings do not pose increased demands on the knee and the hip joint compared to bodyweight only jump-landings, due to the load-based reductions in jump height and joint kinematic adaptions. However, ankle joint contribution in energy dissipation is increased, possibly resulting in an increased overuse injury risk at this joint. Arresting the barbell load at flight apex prior to jump-landing substantially reduces the joint kinetics, hence serving as valuable training tool for athletes returning to sport after injuries.
... The segments' masses were calculated based on the proportions of Dempster. 17 Kinematic and kinetic data were filtered at 15 Hz with a fourth-order bidirectional zero-lag low-pass Butterworth digital filter. ...
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Background An anterior cruciate ligament (ACL) rupture may result in poor sensorimotor knee control and, consequentially, adapted movement strategies to help maintain knee stability. Whether patients display atypical lower limb mechanics during weight acceptance of stair descent at different time frames after ACL reconstruction (ACLR) is unknown. Purpose To compare the presence of atypical lower limb mechanics during the weight acceptance phase of stair descent among athletes at early, middle, and late time frames after unilateral ACLR. Study Design Controlled laboratory study. Methods A total of 49 athletes with ACLR were classified into 3 groups according to time after ACLR—early (<6 months; n = 17), middle (6-18 months; n = 16), and late (>18 months; n = 16)—and compared with asymptomatic athletes (control; n = 18). Sagittal plane hip, knee, and ankle angles; angular velocities; moments; and powers were compared between the ACLR groups’ injured and noninjured legs and the control group as well as between legs within groups using functional data analysis methods. Results All 3 ACLR groups showed greater knee flexion angles and moments than the control group for injured and noninjured legs. For the other outcomes, the early group had, compared with the control group, less hip power absorption, more knee power absorption, lower ankle plantarflexion angle, lower ankle dorsiflexion moment, and less ankle power absorption for the injured leg and more knee power absorption and higher vertical ground reaction force for the noninjured leg. In addition, the late group showed differences from the control group for the injured leg revealing more knee power absorption and lower ankle plantarflexion angle. Only the early group took a longer time than the control group to complete weight acceptance and demonstrated asymmetry for multiple outcomes. Conclusion Athletes with different time frames after ACLR revealed atypically large knee angles and moments during weight acceptance of stair descent for both the injured and the noninjured legs. These findings may express a chronically adapted strategy to increase knee control. In contrast, atypical hip and ankle mechanics seem restricted to an early time frame after ACLR. Clinical Relevance Rehabilitation after ACLR should include early training in controlling weight acceptance. Including a control group is essential when evaluating movement patterns after ACLR because both legs may be affected.
... In addition to the CoP parameters, we analyzed the CoM state (i.e., the position and velocity of the CoM) at the time of the takeoff of the leading leg, which was regarded as the controlled variable of the APA. We calculated the CoM state based on a seven-segment rigid-body model including the right and left thighs, lower legs, feet, and the head, arms, and trunk were considered one segment (Dempster, 1955). The velocity of the CoM was calculated using three-point numerical differentiation. ...
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Motor control for forward step initiation begins with anticipatory postural adjustments (APAs). During APAs, the central nervous system controls the center of pressure (CoP) to generate an appropriate center of mass (CoM) position and velocity for various task requirements. In this study, we investigated the effect of required stepping accuracy on the CoM and CoP parameters during APA for a step initiation task. Sixteen healthy young participants stepped forward onto the targets on the ground as soon as and as fast as possible in response to visual stimuli. Two target sizes (small: 2 cm square and large: 10 cm square) and two target distances (short: 20% and long: 40% of the body height) were tested. CoP displacement during the APA and the CoM position, velocity, and extrapolated CoM at the timing of the takeoff of the lead leg were compared among the conditions. In the small condition, comparing with the large condition, the CoM position was set closer to the stance limb side during the APA, which was confirmed by the location of the extrapolated center of mass at the instance of the takeoff of the lead leg [small: 0.09 ± 0.01 m, large: 0.06 ± 0.01 m, mean and standard deviation, F(1, 15) = 96.46, p < 0.001, η2 = 0.87]. The variability in the mediolateral extrapolated center of mass location was smaller in the small target condition than large target condition when the target distance was long [small: 0.010 ± 0.002 m, large: 0.013 ± 0.004 m, t(15) = 3.8, p = 0.002, d = 0.96]. These findings showed that in the step initiation task, the CoM state and its variability were task-relevantly determined during the APA in accordance with the required stepping accuracy.
... In each recorded field, twenty-two anatomical points of the body (top of the head, neck, shoulder, elbow, wrist, tip of the fingers, hip, knee, ankle, heel, metatarsals, tip of the toe, on both sides of the body) were manually digitized. The coordinates of the body centre of mass (BCM) were calculated as suggested by Dempster (1955). A second-order low-pass Butterworth filter (cut-off frequency: 10 Hz) was selected for smoothing of the raw data. ...
Article
The rising importance of movement analysis led to the development of more complex biomechanical models to describe in detail the human motion patterns. The models scaled from simplistic two-dimensional to three-dimensional representations of body including detailed joint, muscle, tendon, and ligament models. Different computational methodologies have been proposed to extend traditional kinematic and dynamic analysis to include not only the evaluation of muscle forces but also the action of the central nervous system. Hence, a large number of models varying in complexity and target application are available in literature. This narrative review aims to provide an overview of the modeling of biomechanical systems used for the analysis of human movement within the framework of multibody dynamics, for those enrolled in engineering, clinical, rehabilitation and sports applications. The review includes detailed and generic models, as well as the main methodologies applied to model muscle activation and contraction dynamics. Numerous skeletal, musculoskeletal and neuromusculoskeletal models with variable degrees of complexity, accuracy and computational efficiency were identified. An important remark is that the most suitable model depends on the study objectives, detail level of the depicted anatomical structures, target population or performed motion. Summarizing, biomechanical systems have evolved remarkably during the last decades. Such advances allowed to gain a deep knowledge on how the human nervous system controls the movement during different activities, which has been used not only to optimize motor performance but also to develop solutions that allow impaired people to regain motor function in cases of disability, among other applications.
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Gradually, Mobile Ad-hoc Networks (MANETs) play an important role in the construction of smart organization, resident, campus, search/rescue region and battlefield. MANETs are suitable for providing communication support where no fixed infrastructure exists due to conventional networks neither feasible nor economically profitable. These networks are essentially important in the case of a disaster or natural calamities situations for establishing urgent communication among rescue members. The MANET relies on routing protocols to adapt to the dynamic changes in its topology and maintain the supply of routing information to the nodes. This paper provides a comparative analysis to the most popular routing protocols in MANET environments namely, Destination-Sequenced Distance-Vector (DSDV), Ad-hoc On-demand Distance Vector (AODV) and Ad-hoc On-demand Multipath Distance Vector (AOMDV). The compression covers the single-path and multi-path mechanisms, and reactive and proactive behaviors of the protocols in time-critical events of search and rescue missions. The NS2 simulator is used to test and evaluate the performance of these protocols based on throughput (TP), packet delivery ratio (PDR) and packet loss ratios (PLR), and end-to-end delay (E2E delay). The results show that the most suitable MANET routing protocol for time-critical events of search and rescue missions is the AOMDV.
Article
Background Biomechanical effects of anterior knee pain are difficult to distinguish from effects of other factors also related to knee injury (e.g., joint effusion). The purpose of this study was to evaluate independent effects of anterior knee pain on landing and jumping biomechanics. Methods Thirteen healthy participants performed a land and jump movement task, under three experimental conditions (pre-pain, pain, and post-pain), during one data collection session. One 1-ml injection of hypertonic saline into the infrapatellar fat pad was used to induce experimental anterior knee pain during the pain condition. Participant-perceived anterior knee pain was measured every 2 min throughout data collection. Landing and jumping biomechanics were measured and compared between the experimental conditions using a functional statistical approach. Findings The aforementioned injection increased mean participant-perceived anterior knee pain, from zero during the pre-pain condition to 2.6 ± 0.71 cm during the pain condition. Vertical ground reaction force, knee flexion angle, and internal knee extension moment decreased by approximately 0.100 body weights, 3°, and 0.010 Nm/body weight × body height, respectively, between the pre-pain and pain conditions. Conversely, hip flexion angle and internal hip extension moment increased by approximately 3° and 0.006 Nm/body weight × body height, respectively, between the pre-pain and pain conditions. Several biomechanical changes persisted after anterior knee pain abatement (the post-pain condition). Interpretation Anterior knee pain alters landing and jumping biomechanics, independent of other injury-related factors. These altered biomechanics likely change knee joint loading patterns and might increase risk for chronic knee joint injury and/or pathology.
Article
Background: In recent years, the prevalence of medial ulnar collateral ligament injuries has increased in throwers of all ages and skill levels. The motusBASEBALL sensor possesses an inertial measurement unit (IMU) that has been developed and applied to the throwing arm to allow for measurements of several objective parameters, which may prove beneficial for monitoring, rehabilitation, and injury prevention in the throwing athlete. However, the reliability, consistency, and validity of the IMU have not been independently assessed. Purpose: To evaluate the reliability, consistency, and validity of the motusBASEBALL sensor compared with the historic gold standard of marker-based motion capture. Study design: Controlled laboratory study. Methods: A total of 10 healthy male baseball athletes with varsity-level high school experience volunteered to participate in this study. Participants were fitted with 37 retroreflective markers for motion capture and the motusBASEBALL IMU sensor. Participants threw 5 fastballs at maximum effort, with measurements recorded simultaneously by motion capture and the IMU. Arm slot, arm speed, arm stress, and shoulder rotation were measured and compared. Results: Of the 4 metrics generated by the IMU, significant differences were found for 3 of the throwing metrics compared with motion capture including arm slot (5.0°± 6.1°; P = .037), elbow varus torque (9.4 ± 12.0 N·m; P = .037), and shoulder rotation (6.3°± 6.1°; P = .014). Arm speed did not demonstrate a statistically significant difference (29.2 ± 96.8 rpm; P = .375). The IMU consistently underreported pitching performance values. Shoulder rotation exhibited excellent reliability with <5° of error, and arm slot demonstrated good reliability with <10° of error. Arm stress and arm speed were less reliable. Conclusion: The IMU was not accurate or valid for arm slot, arm stress, and shoulder rotation compared with marker-based motion capture. It was relatively accurate for arm speed. Despite its lack of validity, it was consistent and reliable for arm speed and shoulder rotation and relatively reliable for arm slot and arm stress. Caution should be used when comparing values provided by this IMU to the gold standard of marker-based motion capture. Clinical relevance: IMU technology has potential to be used in monitoring, rehabilitation, and injury prevention in throwing athletes if valid. This study demonstrates that the values provided by the IMU should not be considered equivalent to those generated by the gold standard of marker-based motion capture; however, there may still be a role for this technology when relying on its internal consistency for intrathrower comparisons and tracking.
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The purpose of this study was to estimate the body segment density from one MRI image for each body segment by continuously acquiring cross-sectional images of Japanese male and female athletes using MRI. First, a preliminary analysis was conducted for six male and female athletes to determine the range of appropriate cross section selection for estimating the body segment density. Next, we used 21 other male and female athletes as subjects and estimated the body segment density from one MRI image for each body segment. As a result of the preliminary analysis, it was suggested that analysis of one MRI image for each body segment gave the similar value of body segment density as in analyzing many successive MRI images. Moreover, the sex difference in body segment densities between the male and female athletes and the difference in body segment densities between the athletes and the cadaver specimens (Caucasian middleaged or aged males) were clarified.
Thesis
This thesis examines the medio-lateral body motion during single steps in an attempt to understand how balance is controlled in human stepping and gait. During a step the body's centre of mass (CoM) is not over the base of support. The body is unstable and falls sideways, but is 'held together' such that it moves approximately as a single unit. Over a range of step directions, there is a close relationship at the end of the step between stepping foot position and CoM position and velocity. This may be in order that the stepping limb can catch and redirect the fall of the body securely. A freely- falling model of the body closely predicts body motion during the step. This suggests that the position and velocity of the CoM at the end of the step are determined by the values at the start. Subjects are found to vary these starting values systematically with step direction and duration, and also to take into account initial posture. Together with evidence that the duration of the single-support phase is determined in advance, this suggests that the body motion during the step could be controlled ballistically. This strategy may be used because body motion is difficult to influence appreciably once the step is under way. In responding to a cue to change step direction 'midflight', subjects are able to alter body motion but 1) are more able to increase than to decrease the rate of the sideways fall, and 2) appear to have to resort to a multi-segment strategy. In contrast, responses appearing in the swing limb at short latency suggest that ordinarily swing limb motion may be subject to 'on-line' control. Thus inaccuracies in the ballistic control of the body mass may be compensated for by mid-step alterations in swing limb motion.
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Objective: In soccer, vertical jump means jumping toward a ball. Since no vertical jump test includes the ball as a reference element, the effect that the ball would have in a vertical jump test is unknown. The aim of this study was to examine the biomechanical differences between run-up vertical jump measurements without (Run-up Vertical Jump) and with ball inclusion (Heading Test). Methods: Twelve semi- and professional soccer players were recruited. Athletes performed both jump tests in a biomechanical laboratory, where kinetic and spatiotemporal variables were collected and compared using a Student’s dependent t-test for paired samples. Results: Overall, players performed a different jumping strategy during the heading test compared to the run-up vertical jump, exhibiting: 1) higher horizontal velocity during initial contact (+45.3%, P ≤ .001), 2) shorter contact time, greater rate of force development, and total impulse during push-off (+27.5%, +53%, and +10.6%, respectively, P ≤ .008), 3) higher CoM horizontal and resultant velocity during take-off (+76.1% and 20.5%, respectively, P ≤ .001), 4) better vertical jump performance (+4.3%, P ≤ .0001), and 5) larger body angle rotation during landing (+63.3%, P = .006), compared to run-up vertical jump (effect size: 0.78 to 3.7). Conclusion: In general, soccer players display greater vertical jump heights in heading test, which highlights the importance of including an overhead ball during soccer-specific jump tests. Coaches and practitioners are encouraged to assess, and perhaps develop, the jumping ability of soccer players using a suspended ball as a specific target.
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[Purpose] The purpose of this study was to elucidate the age-related changes in the stability of the quiet standing posture based on the acceleration of the center of mass of each body segment under deteriorated somatosensory conditions. [Participants and Methods] The participants in this study were 18 healthy elderly persons and 11 healthy young adults. A foam surface was placed on the force plate for load-bearing onto the somatosensory system. The participants maintained a quiet position on the force plate under two conditions: a firm surface and a foam surface. The accelerations of the head, thorax, pelvis, and whole body center of mass when quiet standing in two conditions were measured by a motion capture system. In the statistical analysis, regarding the center of mass of each body segment, the interactions were examined by performing a two-way analysis of variance using age and surface condition as factors. [Results] A two-way analysis of variance detected an interaction between age and surface factors for anteroposterior acceleration at the center of mass of the head. For other body segments, interactions between the two factors were not detected. [Conclusion] The results of anteroposterior acceleration at the center of mass of the head suggest that under conditions of deteriorated somatosensory function in the lower limbs, minute anteroposterior position adjustment of the head is an essential characteristic of the standing posture control mechanism in the elderly.
Article
Humans are made up of mostly soft tissue that vibrates during locomotion. This vibration has been shown to store and dissipate energy during locomotion. However, the effects of soft tissue vibration (wobbling masses) on the dynamics of bipedal walking have not been assessed in terms of stability. Given that much of the human body is vibrating just following foot-ground contact, it may have dynamic implications on the stability of walking. A rigid bipedal walker and a bipedal walker with soft tissue were simulated to quantify the effects of soft tissue vibration on gait periodicity, orbital stability, global stability, and robustness to uneven terrain. It was found that moderate amounts of energy dissipation resulted in much more stable walking dynamics relative to that of a rigid bipedal walker.
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The accuracy and accessibility of methods to calculate body segment inertial parameters are a key concern for many researchers. It has recently been demonstrated that the magnitude and orientation of principal moments of inertia are crucial for accurate dynamic models. This is important to consider given that the orientation of principal axes is fixed for the majority of geometric and regression body models. This paper quantifies the effect of subject specific geometry on the magnitude and orientation of second moments of volume in the trunk segment. The torsos of 40 male participants were scanned using a 3D imaging system and the magnitude and orientation of principal moments of volume were calculated from the resulting geometry. Principal axes are not aligned with the segment co-ordinate system in the torso segment, with mean Euler angles of 11.7, 1.9 and 10.3 in the ZXY convention. Researchers using anatomical modelling techniques should try and account for subject specific geometry and the mis-alignment of principal axes. This will help to reduce errors in simulation by mitigating the effect of errors in magnitude of principal moments.
Conference Paper
In the current study, we present a 3D mathematical model of the human body for evaluation of the mass-inertial characteristics of all segments of the body. Specific realization of the model is proposed based on anthropometric data for Bulgarian population provided by the representative anthropological investigation of 2435 males of the Bulgarian population at the age between 30-40 years [1]. Using the proposed model, after deriving the corresponding analytical expressions needed for the geometrical bodies used in the modeling, we provide analytical expressions and estimate numerically the mass-inertial characteristics of all of the segments of the body: their mass, center of mass, the volume, and the principal moments of inertia. The comparison between our model results and data reported in literature for other Caucasian shows an overall good agreement, thus supporting the validity of the described method. The model is expected to be applicable in medicine, rehabilitation robotics, sports, ergonomics, computer simulations, etc.
Chapter
Among all possible postures of the human body, NASA selected eight of principle importance for space exploration. The current article aims to determine the mass-inertial characteristics of the human body of the average Bulgarian male in one of these positions—the so-called relaxed, or weightless position. We determine the corresponding characteristics of the centre of mass and principal moments of inertia using a 16-segmental biomechanical mathematical model that is generated within the SolidWorks environment. We verify the model by comparing the analytical results for each of the body segments with the results obtained using the computer model. The geometric data needed for the construction of the 3D model are taken to be in correspondence with experimentally available anthropometric data for about 2500 Bulgarian men. One their basis one determines the characteristics of the average Bulgarian men. Then, using the CAD realization of the model the inertial parameters of this “average” male in different body positions can be determined. The comparison made between our model results described in this article and the data reported in the literature, where available, gives us confidence that the suggested model can be used to calculate the properties in question at any postures of the body of interest. In principle, our approach can be also used to calculate the corresponding mass inertial data for any individual provided that the anthropometric set of parameters for that individual are measured. The model we used is suitable when one needs such parameters in problems appearing not only in space exploration with the participation of male astronauts but also in rehabilitation, sport, criminology, robotics, etc.
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