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Tytuł:
What can normal gait biomechanics teach a designer of lower limb prostheses
Autorzy:
Pitkin, M.
Powiązania:
https://bibliotekanauki.pl/articles/306996.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
biomechanics
prosthetics
anthropomorphicity
biomechanika
protetyka
Opis:
Compensating a limb loss with prosthesis is a challenging task due to complexity of the human body which cannot be fully matched by the available technical means. Designer of lower limb prostheses wants to know what specification of the device could provide the best approximation to the normal locomotion. Deep understanding of the latter is essential, and gait analysis may be a valuable tool for this. Once prosthesis is built, gait analysis may help in comparing the wearer’s performance with the new device and with the prior art, and in verification of the hypotheses being put forward during the development process. In this lecture, we will discuss some synergies of normal gait. We will focus on the required biomechanical properties of a prosthetic leg that can allow the prosthesis’s inclusion in normal gait synergy without demanding excessive compensatory movements. We will consider contribution of leg joints to generation of propulsion for adequate design of lower limb prostheses especially those with power supply.
Źródło:
Acta of Bioengineering and Biomechanics; 2013, 15, 1; 3-10
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Countermovement depth – a variable which clarifies the relationship between the maximum power output and height of a vertical jump
Autorzy:
Gajewski, J.
Michalski, R.
Buśko, K.
Mazur-Różycka, J.
Staniak, Z.
Powiązania:
https://bibliotekanauki.pl/articles/306825.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
ćwiczenia
biomechanika
alometria
exercise
biomechanics
regression
allometry
Opis:
The aim of this study was to identify the determinants of peak power achieved during vertical jumps in order to clarify relationship between the height of jump and the ability to exert maximum power. Methods: One hundred young (16.8±1.8 years) sportsmen participated in the study (body height 1.861 ± 0.109 m, body weight 80.3 ± 9.2 kg). Each participant performed three jump tests: countermovement jump (CMJ), akimbo countermovement jump (ACMJ), and spike jump (SPJ). A force plate was used to measure ground reaction force and to determine peak power output. The following explanatory variables were included in the model: jump height, body mass, and the lowering of the centre of mass before launch (countermovement depth). A model was created using multiple regression analysis and allometric scaling. Results: The model was used to calculate the expected power value for each participant, which correlated strongly with real values. The value of the coefficient of determination R2 equalled 0.89, 0.90 and 0.98, respectively, for the CMJ, ACMJ, and SPJ jumps. The countermovement depth proved to be a variable strongly affecting the maximum power of jump. If the countermovement depth remains constant, the relative peak power is a simple function of jump height. Conclusions: The results suggest that the jump height of an individual is an exact indicator of their ability to produce maximum power. The presented model has a potential to be utilized under field condition for estimating the maximum power output of vertical jumps.
Źródło:
Acta of Bioengineering and Biomechanics; 2018, 20, 1; 127-134
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of contact characteristics of a patient-specific artificial dysplastic hip joint
Autorzy:
Mutlu, I.
Ugur, L.
Celik, T.
Buluc, L.
Muezzinoglu, U. S.
Kisioglu, Y.
Powiązania:
https://bibliotekanauki.pl/articles/306768.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
biomechanics
pressure
hip dysplasia
biomechanika
ciśnienie
biodro
Opis:
This study addresses the results of the experimental measurements for the contact surface areas and contact pressure distributions of a dysplastic hip joint. The hip joint consists of pelvis, proximal femur and artificial cartilages for both acetabulum and femoral head. The dysplastic hip joint is modeled in three dimensional (3D) form using the computerized tomography (CT) images obtained in vivo of an adult female patient. The modeled hip joint components are manufactured as a non-natural dysplastic hip joint using different materials and manufacturing processes. The dysplastic hip joint produced is subjected to compression forces experimentally to measure the contact surface area and contact pressure distributions between the femoral head and acetabulum using the pressure sensitive Fuji film. Different types of specific fixtures and molds are designed and manufactured to produce the dysplastic hip joint components and perform the experimental studies. The measured results using a non-natural dysplastic hip joint are compared with relevant results reported in current literature considering the peak and mean contact pressure values. Therefore, the obtained results showed that the non-natural dysplastic hip models can be generated and replaced to determine the contact characteristics for an elusive cadaveric model. In conclusion, the artificial models might be useful to understand the contact pressure distributions and potential changes in surface pressure contours and their effects on the stress distributions.
Źródło:
Acta of Bioengineering and Biomechanics; 2014, 16, 2; 111-120
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative study of potential whiplash injuries for different occupant seated positionsm during rear end accidents.
Autorzy:
Omerovic, S.
Tomasch, E.
Gutsche, A. J.
Prebil, I.
Powiązania:
https://bibliotekanauki.pl/articles/306862.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
biomechanika
LS-Dyna
FEM
kręgosłup
biomechanics
whiplash
spine
Opis:
Purpose: Whiplash injuries to the cervical spine represent a considerable economic burden on society with medical conditions, in some cases persisting for more than a year. Numerous studies of whiplash injuries have been made for occupant normal seated position, leaving the analysis of neck injuries for out-of-normal positions not well documented. For that purpose, a detailed human cervical spine finite element model was developed. Methods:The analysis was made for four most common occupant seated positions, such as: Normal Position with the torso against the seat back and the head looking straight ahead, Torso Lean forward position with the torso away from the seat back for approximately 10°, Head Flexed position with the head flexed forward approximately 20° from the normal position and HeadFlexed with Torso Lean forward position with the head flexed forward approximately 20° and torso 10° from the normal position. Results: The comparative study included the analysis of capsular ligament deformation and the level of S-curvature of the cervical spine. The developed model predicted that Head Flexed seated position and Head-Flexed with Torso Lean forward seated position are most threatening for upper and lower cervical spine capsular ligament respectively. As for the level of S-curvature, the model predicted that Head-Flexed with Torso Lean forward seated position would be most prone to neck injuries associated with it. Conclusions:This study demonstrated that the occupant seated position has a significant influence on potential whiplash injuries.
Źródło:
Acta of Bioengineering and Biomechanics; 2016, 18, 4; 145-158
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anthropometric predispositions for swimming from the perspective of biomechanics
Autorzy:
Rejman, M.
Tyc, Ł.
Kociuba, M.
Bornikowska, A.
Rudnik, D.
Kozieł, S.
Powiązania:
https://bibliotekanauki.pl/articles/306959.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
pływanie
profil antropometryczny
biomechanika
swimming
anthropometric profile
biomechanics
Opis:
Early identification of anthropological potential in swimmers is considered important to the recruitment and selection of children and adolescents to perform extensive and strenuous training. The aim of the research was a comparative analysis of the anthropometric parameters and indicators of adult, elite swimmers with people who had never trained for swimming. It was assumed that the specific characteristics of the swimmers’ somatic composition referred to the laws of swimming biomechanics. Methods: Anthropometric measurements were taken in a group of elite male swimmers (N = 28), aged 17–24. The same set of measurements was taken in a homogeneous control group of students of physical education. An anthropometric profile significantly differentiating swimmers from the control group was constructed. Next, a linear forward stepwise discriminant analysis was conducted to investigate which indices can be used to distinguish the two groups. Results: It seems significant that a specific somatic composition trait of swimmers in the form of a relatively long shank was observed, which had not been observed in earlier studies. Additionally, indices of relatively slim hand dimension, and indices describing a “reversed triangle” shape of trunk, were the most powerful discrimination variables between the two examined groups. Conclusion: The results obtained cannot be generalised to the entire population of swimmers, however referring them to the laws of biomechanics of swimming allows for the continuation of research into identifying the prognostic traits desirable for success among young swimmers.
Źródło:
Acta of Bioengineering and Biomechanics; 2018, 20, 4; 151-159
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acute effects of different orthoses on lower extremity kinetics and kinematics during running; a musculoskeletal simulation analysis
Autorzy:
Sinclair, Jonathan
Ingram, Jane
Taylor, Paul John
Chockalingam, Nachiappan
Powiązania:
https://bibliotekanauki.pl/articles/307279.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
bieg
orteza
biomechanika
patologia
running
orthoses
biomechanics
pathology
Opis:
The current investigation aimed to examine the effects of different orthotic conditions on the biomechanical mechanisms linked to the aetiology of chronic pathologies using musculoskeletal simulation. Methods: 16 male and 20 females ran over an embedded force plate at 4.0 m/s, in five different conditions (medial, lateral, no-orthoses, semi-custom and off the shelf). Kinematics of the lower extremities were collected using an eight-camera motion capture system and lower extremity joint loading also explored using a musculoskeletal simulation approach. Differences between orthoses conditions were examined using 2 2 mixed ANOVA. Results: External instantaneous load rate was significantly reduced in the off the shelf orthoses (male = 1290.60 and female = 1567.10 N/kg/s), compared to the medial (male = 1480.45 and female = 1767.05 N/kg/s) and semi-custom (male = 1552.99 and female = 1704.37 N/kg/s) conditions. In addition, peak patellofemoral stress was significantly lower in the off the shelf orthoses (male = 68.55 and female = 94.91 KPa/kg) compared to the lateral condition (male = 70.49 and female = 103.22 KPa/kg). Finally, peak eversion angles were significantly attenuated in the medial orthoses (male = –6.61 and female = –7.72 deg) compared to the lateral (male = –9.61 and female = –10.32 deg), no-orthoses (male = –8.22 and female = –10.10 deg), semi-custom (male = –8.25 and female = –9.49 deg) and off the shelf (male = –7.54 and female = –8.85 deg) conditions. Conclusions: The current investigation shows that different orthotic devices/ configurations may provide distinct benefits in terms of their effectiveness in attenuating the biomechanical parameters linked to the aetiology of chronic running injuries.
Źródło:
Acta of Bioengineering and Biomechanics; 2019, 21, 4; 13-25
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of functional and structural changes affecting the lumbar spine in professional field hockey players
Autorzy:
Ogurkowska, M. B.
Kawałek, K.
Powiązania:
https://bibliotekanauki.pl/articles/307011.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
przeciążenie
medycyna sportowa
biomechanika
kość
overload
sports medicine
biomechanics
bone
Opis:
Purpose: The aim of this study was to evaluate functional and structural changes in the lumbar spine. Methods: The research group consisted of 20 male professional field hockey players. Computed tomography scans were collected to define the radiological density of the vertebral bodies and to calculate Young’s modulus. An electrogoniometer was used to measure the range of movement. Geometric parameters, such as Lumbar Lordosis Angle, Index of Lumbar Lordosis, Whitmann-Ferguson Angle and Anterior Pelvic Tilt, were also measured. Results: The values describing lumbar lordosis increased linearly with years of training and were significantly greater than those reported in the literature. Field hockey players displayed a larger range of flexion, side bending and rotation to the right. An analysis of radiological density found significantly high values. An analysis of Young’s modulus showed that the vertebral bodies become more fragile. Conclusions: The results show that overuse changes in the lumbar spine of field hockey players are severe and highly correlated with years of training.
Źródło:
Acta of Bioengineering and Biomechanics; 2017, 19, 2; 51-58
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Corneal hyper-viscoelastic model: derivations, experiments, and simulations
Autorzy:
Su, P.
Yang, Y.
Song, Y
Powiązania:
https://bibliotekanauki.pl/articles/307042.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
rogówka
biomechanika
hiperelastyczność
lepkosprężystość
cornea
biomechanics
constitutive model
hyperelastic
viscoelastic
Opis:
Purpose: The aim of this study is to propose a method to construct corneal biomechanical model which is the foundation for simulation of corneal microsurgery. Methods: Corneal material has two significant characteristics: hyperelastic and viscoelastic. Firstly, Mooney–Rivlin hyperelastic model of cornea obtained based on stored-energy function can be simplified as a linear equation with two unknown parameters. Then, modified Maxwell viscoelastic model of the cornea, whose analytical form is consistent with the generalized Prony-series model, is proposed from the perspective of material mechanics. Results: Parameters of the model are determined by the uniaxial tensile tests and the stress-relaxation tests. Corneal material properties are simulated to verify the hyper-viscoelastic model and measure the effectiveness of the model in the finite element simulation. On this basis, an in vivo model of the corneal is built. And the simulation of extrusion in vivo cornea shows that the force is roughly nonlinearly increasing with displacement, and it is consistent with the results obtained by extrusion experiment of in vivo cornea. Conlusions: This paper derives a corneal hyper-viscoelastic model to describe the material properties more accurately, and explains the mathematical method for determination of the model parameters. The model is an effective biomechanical model, which can be directly used for simulation of trephine and suture in keratoplasty. Although the corneal hyper-viscoelastic model is taken as the object of study, the method has certain adaptability in biomechanical research of ophthalmology.
Źródło:
Acta of Bioengineering and Biomechanics; 2015, 17, 2; 73-84
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanical energy flows between body segments in ballistic track-and-field movements (shot put, discus, javelin) as a performance evaluation method
Autorzy:
Błażkiewicz, Michalina
Łysoń, Barbara
Wit, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/307218.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
biomechanika
energia mechaniczna
tor
biomechanics
mechanical energy
track and filed
Opis:
Seeking a method to evaluate and monitor the performance of the shot put, discus and javelin throw, we analyzed the transfer of mechanical energy between body segments. Methods: The study was conducted on groups consisting of elite throwers on the Polish National Team for each of the aforementioned sport disciplines. The movements of each throw were recorded using Vicon system and Kistler plates. The power and energy fluctuations were computed for the final acceleration phase of each throw. Results: In all three disciplines studied, we found an average energy loss of 1.63 J/kg generated from shoulder to wrist. The value of generated energy from ankle to torso initially increased in all disciplines, followed by a descent – with the exception of the javelin throw, where there was an average 27% decrease in both hip joints. We found strong correlations between relative amplitude values of energy and the athlete’s personal performance records: –0.8226 (shot put), 0.6008 (discus) and 0.7273 (javelin). Conclusions: Measuring the transfer of mechanical energy between body segments offers a useful method for evaluating the technique of ballistic movements and for monitoring training progress.
Źródło:
Acta of Bioengineering and Biomechanics; 2019, 21, 1; 31-36
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of muscle load and fatigue with the usage of frequency and time-frequency analysis of the EMG signal
Autorzy:
Bartuzi, P.
Roman-Liu, D.
Powiązania:
https://bibliotekanauki.pl/articles/307422.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
biomechanics
EMG
fatique
muscle load
wavelet
mięśnie
obciążenie
zmęczenie
falka
Opis:
The aim of the study was to determine the effect of the muscle load and fatigue on the values of the parameters calculated on the basis of the time, frequency (Fourier transform) and time-frequency (wavelet transform) analysis of the EMG signal, for low levels of load. Fifteen young men took part in the study. The EMG signal was registered from right side biceps brachii (BB) and trapezius (TR) muscles in static conditions, at load 10%, 20% and 30% MVC (maximal voluntary contraction). On the basis of the analysis there were selected parameters sensitive to force (RMS) and parameters sensitive to fatigue but simultaneously insensitive to force (MPF – mean power frequency determined on the basis of Fourier transform, CMPFdb5 – mean power frequency determined on the basis of the wavelet transform). The results indicate that CMPFdb5 can show similar (muscle BB) or greater (muscle TR) sensitivity to fatigue than MPF. It can suggest that, for low levels of load, the wavelet transform parameters can be more effective in assessing muscle fatigue than the parameters based on the Fourier transform. The obtained results can allow for a more precise analysis of muscle fatigue at low levels of load. Further analysis for a greater number of muscles activated at low levels of load, with the usage of the parameters tested is desirable.
Źródło:
Acta of Bioengineering and Biomechanics; 2014, 16, 2; 31-39
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Medial longitudinal arch biomechanics evaluation during gait in subjects with flexible flatfoot
Autorzy:
Prachgosin, T.
Chong, D. Y. R.
Leelasamran, W.
Smithmaitrie, P.
Chatpun, S.
Powiązania:
https://bibliotekanauki.pl/articles/307263.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
biomechanika
chód
płaskostopie
biomechanics
gait
medial longitudinal arch
flat foot
Opis:
Purpose: Medial longitudinal arch (MLA) strengthening has been considered an important part of successful flatfoot treatment. But, to date, the biomechanical loading behavior of the medial arch in flatfoot has not been evaluated. This study aimed to evaluate the MLA moment, MLA deformation angle, foot kinematics and ground reaction forces (GRF) in both normal foot and flatfoot groups. Methods: Each participant’s foot was classified according to arch type using foot prints and radiographs. Twenty-eight non-obese adults (13 flatfeet and 15 normal feet) were involved. The biomechanics data were collected in a 3D motion analysis laboratory. The MLA biomechanics were calculated. Hindfoot and forefoot kinematics were also analyzed. Results: The flatfoot group had a significantly greater peak eversion MLA moment ( p = 0.005) and a smaller peak MLA deformation angle ( p < 0.05) during specific subphases. The peak of hindfoot plantarflexion ( p < 0.05) and internal rotation ( p < 0.05) and the peak of forefoot abduction ( p < 0.05) in the specific subphases were greater in the flatfoot group. The flatfoot group also had significantly smaller peak vertical GRF ( p < 0.05) during late stance and larger peak medial GRF ( p < 0.05) during mid stance. Conclusions: This study found a significantly greater eversion deforming force acting at the MLA structure, greater hindfoot and forefoot motion, less MLA flexibility and abnormal GRF in a flatfoot group during walking, which reflected the deficit of foot function in a flatfoot group.
Źródło:
Acta of Bioengineering and Biomechanics; 2015, 17, 4; 121-130
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of the front part of the vehicle and cyclist’s sitting position on the severity of head injury in side collision
Autorzy:
Fanta, O.
Boucek, J.
Hadraba, D.
Jelen, K.
Powiązania:
https://bibliotekanauki.pl/articles/307524.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
bicycle
biomechanics
head injury
multibody simulation
rower
biomechanika
głowa
symulacja
Opis:
An injury of cyclists during a collision with a car is currently a neglected topic. Most research projects evaluate in detail the injury of pedestrians, but with an increasing number of cyclists it will be necessary to devote more attention to their safety. This study is focused on the most common type of collision and offers insights into the biomechanics of cyclist’s head injury without the use of bicycle helmet. Initial mechanical and kinematic conditions that affect Head Injury Criterion (HIC) after a car hits a cyclist were determined using simulation software MADYMO. In relation to HIC, three different shapes of the front part of the car and three basic cyclist’s positions were compared.
Źródło:
Acta of Bioengineering and Biomechanics; 2013, 15, 1; 105-112
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kinematic gait analysis in children with valgus deformity of the hindfoot
Autorzy:
Svoboda, Z.
Honzikova, L.
Jaroszczuk, S.
Vidal, T.
Martinaskova, E.
Powiązania:
https://bibliotekanauki.pl/articles/306230.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
chód
płaskostopie
kinematyka
biomechanika
walking
calcaneal eversion
heel
flat foot
biomechanics
Opis:
Deformities of the feet in children can influence not only optimal foot development but also the development of other body segments. The aim of the study was to compare the hip and pelvis kinematics in groups of children with and without valgus deformity of the hindfoot. Three groups of children participated in the study: bilateral hindfoot valgosity (11 children, age 5.4±1.4 years), unilateral hindfoot valgosity (14 children, age 5.6±1.6 years) and the control group (8 children). Hindfoot valgus was measured clinically during standing. Hindfoot valgosity was considered in the range of 6 to 20 degrees. Kinematic data from five trials for each child was obtained using the Vicon MX system (six infrared cameras, frequency 200 Hz, Vicon Motion Systems, Oxford, UK). The results of our study showed significantly higher pelvic anteversion during the whole gait cycle for both unilateral and bilateral hindfoot valgosity children and significantly higher hip external rotation during the first half of the stance phase in bilateral deformity. The differences in the hip and pelvis kinematics, when compared to the control group, are higher for the group with bilateral deformity than in the group with unilateral deformity.
Źródło:
Acta of Bioengineering and Biomechanics; 2014, 16, 3; 89-93
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Jumping performance and take-off efficiency in two different age categories of female volleyball players
Autorzy:
Jandova, Sona
Janura, Miroslav
Powiązania:
https://bibliotekanauki.pl/articles/306340.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
biomechanika
skoki
wysokość
siła
wiek
biomechanics
vertical jump
height
power
age
Opis:
Vertical jump height is recognised as a determinant factor in elite volleyball performance. In previous studies there are different opinions on whether vertical jump height performance improves during maturation or not. The aim of this study was to assess the differences in jumping abilities in two different age groups of female volleyball players and to determine the take-off efficiency during repeated jumps. Methods: Seventeen female volleyball players from two different age categories – adults and under 16 years – participated in this study. Quattro Jump 9290BA force platform (Kistler, Winterthur, Switzerland) was used to assess the jumping performance during squat jumps, counter movement jumps, and 45-second continuous jumps. Results: Jumping performance did not differ significantly between the two groups. The main efficiency of the conversion of mechanical work into mechanical energy was only 24% and it decreased during the test. Conclusions: The influence of age on the jumping performance in a group of female volleyball players was not confirmed. Take-off efficiency was in both groups quite low and it did not improve during the test.
Źródło:
Acta of Bioengineering and Biomechanics; 2019, 21, 2; 55-61
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Biomechanical simulation of needle insertion into cornea based on distortion energy failure criterion
Autorzy:
Su, P.
Yang, Y.
Huang, L.
Powiązania:
https://bibliotekanauki.pl/articles/306549.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
rogówka
biomechanika
symulacja matematyczna
cornea
biomechanics
insertion force
suture
mathematical simulation
Opis:
Purpose: This paper is mainly about biomechanical behavior of needle insertion into cornea, and proposes a failure criterion to simulate the insertion process which has attracted considerable attention due to its importance for the minimally invasive treatment. Methods: In the process of needle insertion into cornea, tiny and complex insertion force is generated due to contact between needle and soft tissue. Based on the distortion energy theory, there is proposed a failure criterion of corneal material that can solve contact problem between rigid body and biological tissue in insertion simulation, where Cauchy stress of corneal material is the key to numerical calculation. A finite element model of in vivo cornea is built, and the cornea constrained by sclera is simplified to two layers containing epithelium and stroma. Considering the hyper-viscoelastic property of corneal material, insertion simulation is carried out. Results: By insertion experiment, the insertion force increases with insertion depth accompanying obvious fluctuations. Different insertion forces are generated at different speeds. The punctured locations are obvious in the force-displacement curves. The results of insertion simulation are generally consistent with experimental data. Maps of von Mises stress reflect the tissue injury of the cornea during insertion process, and punctured status corresponds to the point in the curves. Conclusions: The ability of this study to reproduce the behavior of needle insertion into cornea opens a promising perspective for the control of robotic surgery operation as well as the real-time simulation of corneal suture surgery.
Źródło:
Acta of Bioengineering and Biomechanics; 2016, 18, 1; 65-75
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 51

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