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EN
Minimally-supervised home rehabilitation has become an arising technological trend due to the shortages in medical staff. Implementing such requires providing advanced tools for automatic real-time safety monitoring. The paper presents an approach to designing the mentioned safety system based on measurements and modelling the interface between a patient’s musculoskeletal system and a rehabilitation device. The content covers the segmentation of patients regarding their health conditions and assigns them suitable measurement techniques. The defined groups are described by the hazards with which they are most endangered and their causes. Each case is correlated with the appropriate data type that may be used to detect potential risk. Moreover, a concept of using presented knowledge for tracking the safety of bones and soft tissues according to the biomechanical standards is included. The paper forms a set of guidelines for designing safety systems based on measurements for robot-aided home kinesiotherapy. It can be used to select an appropriate approach regarding a specific case; which will decrease costs and increase the accuracy of the designed tools.
EN
The aim of this work was to i nvestigate the effects of midsole thickness on non-rearfoot strike runners’ redistributions of knee and ankle joint negative and positive work. Methods: Fourteen healthy male runners wore minimalist, traditional and maximalist shoes and ran in a straight line in each shoe in the laboratory at a speed of 15 km/h, with a ±5% difference being allowed. Whole-body kinematics and ground reaction forces were recorded, and the data of eleven non-rearfoot strikers were used for the analysis. Ankle and knee joint negative and positive work was calculated by integrating each joint’s torque power. Friedman test was used for statistical comparisons. Results: Running in minimalist shoes induced significantly greater ankle joint negative and positive work than in other shoes. Running in maximalist shoes induced significantly lower ankle joint positive work and greater knee joint negative work than in other shoes, and significantly greater knee joint positive work than in minimalist shoes. Conclusions: Our results indicated that nonrearfoot strikers redistributed joint negative and positive work from the knee to the ankle when using minimalist shoes or from the ankle to the knee when using maximalist shoes. It is recommended that future research employs more rigorous study designs, such as randomised controlled trials and longitudinal studies, to provide a more accurate assessment of the effect of these shoes on injury rates.
EN
Fixed prosthetic restorations must meet the health requirements in terms of the protection of the tissues of the oral cavity, biomechanical requirements for optimal tissue stress and the strength and wear resistance of the structure, aesthetic requirements related to the location of the gingival margin, as well as the shape, thickness, and colour of the veneers. The aim is to evaluate the impact of manufacturing technology on the microstructure and micromechanical parameters of titanium crowns. The material of the analysis are prosthetic crowns made of Ti6Al4V alloy for the maxilla premolars and the mandible molars, produced using two technologies: Selective Laser Melting (SLM) and CAD/CAM milling. Crown structures were evaluated on the basis of examinations of the microstructure and surface layer of the chamfers, micromechanical parameters in axial sections perpendicular to the dental arches, and the accuracy of mapping the internal shape in sections with horizontal planes perpendicular to the axis of the abutment tooth. The results of this work can be used in a clinical setting. They allow the evaluation of what is the impact of the technology of producing the supporting substructure on the structure of the prosthetic crown. The strength requirements in both technologies are met, while the higher value of the microhardness of the titanium SLM substructure, compared to the milled one, increases the stiffness of the structure under conditions of biomechanical excitation. The errors in mapping the internal shape of the crowns are comparable and slightly higher during sintering.
PL
Stałe uzupełnienia protetyczne powinny spełniać wymagania zdrowotne w aspekcie zabezpieczenia tkanek jamy ustnej, wymagania biomechaniczne dotyczące optymalnego wytężenia tkanek oraz wytrzymałości i odporności na zużycie konstrukcji, wymagania estetyczne związane z usytuowaniem obrzeża dodziąsłowego, a także kształtem, grubością i kolorem licowania. Celem jest ocena wpływu technologii wytwarzania na mikrostrukturę i parametry mikromechaniczne koron tytanowych. Materiałem analizy są korony protetyczne ze stopu Ti6Al4V na zęby przedtrzonowe szczęki i trzonowe żuchwy wytwarzane dwoma technologiami: Selective Laser Melting (SLM) i frezowania CAD/CAM. Konstrukcje koron oceniano na podstawie badań mikrostruktury i warstwy wierzchniej stopni, parametrów mikromechanicznych w osiowych przekrojach prostopadłych do łuków zębowych oraz dokładności odwzorowania kształtu wewnętrznego w przekrojach płaszczyznami horyzontalnymi, prostopadłymi do osi zęba filarowego. Wyniki tej pracy mogą być wykorzystane w warunkach klinicznych. Pozwalają ocenić, jaki jest wpływ technologii wytworzenia podbudowy nośnej, na konstrukcję korony protetycznej. Wymagania wytrzymałościowe w obu technologiach są spełnione, przy czym wyższa wartość mikrotwardości podbudowy tytanowej z SLM, w porównaniu do frezowanej, wpływa na zwiększenie sztywności konstrukcji w warunkach wymuszeń biomechanicznych. Błędy odwzorowania kształtu wewnętrznego koron są porównywalne i nieco wyższe przy spiekaniu.
PL
Instytut Informatyki oraz Wydział Mechatroniki Uniwersytetu Kazimierza Wielkiego wraz z firmą Edurewolucje Sp. z o. o. z/s w Bydgoszczy w ramach konkursu Narodowego Centrum Badań i Rozwoju "Rzeczy są dla ludzi" otrzymali dofinansowanie na realizację przedsięwzięcia pn. „Opracowanie funkcjonalnego egzoszkieletu ręki do aktywnego treningu i rehabilitacji”. Celem projektu jest realizacja prac badawczo-rozwojowych prowadzących do opracowania innowacyjnej technologii pozwalającej na samodzielną rehabilitację osób ze szczególnymi potrzebami (przy udziale rehabilitantów i fizjoterapeutów). Projekt przewiduje skonstruowanie prototypu mechanicznego robota rehabilitacyjnego tzw. egzoszkieletu ręki, który wspomoże proces rehabilitacji osób z jej niedowładem oraz innymi szczególnymi potrzebami dotyczącymi braku mobilności w obszarze ręki. W ramach projektu powstanie specjalistyczne, dedykowane oprogramowanie, które będzie dostosowywało siłę i rodzaj pracy egzoszkieletu na rękę do aktualnych potrzeb i celów programu rehabilitacyjnego pacjenta. Celem niniejszej pracy jest przybliżenie powstania i rozwoju ww. koncepcji w ramach zespołu projektowego podczas dotychczasowych prac projektowych.
EN
The Institute of Computer Science and the Faculty of Mechatronics at Kazimierz Wielki University, together with Edurewolucje Sp. z o. o. z/s in Bydgoszcz, received funding under the 'Things are for people' competition of the National Centre for Research and Development for the project entitled 'Development of a functional arm exoskeleton for active training and rehabilitation'. The aim of the project is to carry out research and development work leading to the development of an innovative technology allowing for the independent rehabilitation of people with special needs (with the participation of rehabilitators and physiotherapists). The project envisages the construction of a prototype of a mechanical rehabilitation robot, the so-called hand exoskeleton, which will support the process of rehabilitation of people with paresis and other specific needs regarding lack of mobility in the hand area. The project will develop specialised, dedicated software that will adapt the strength and type of work of the hand exoskeleton to the current needs and goals of the patient's rehabilitation programme. The aim of this paper is to provide an insight into the origins and development of the above concept within the project team during the project work to date.
PL
W artykule pokrótce przedstawiono modele manekinów zderzeniowych pieszych, dzieląc je na manekiny stosowane typowo na potrzeby projektowania pojazdów oraz stosowane w badaniach rekonstrukcyjnych wypadków drogowych. Przedstawiono wybrane badania z dziedziny rekonstrukcji wypadków drogowych, w których wykorzystywane były manekiny pieszych. W drugiej części artykułu przedstawiono konstrukcję manekina PRIMUS - produktu od niedawna dostępnego na rynku. Opisano budowę manekina i podsumowanie badań weryfikujących jego odpowiedź dynamiczną w warunkach potrącenia oraz wymieniono potencjalne jego zastosowania, takie jak rekonstrukcje wypadków i badania eksperymentalne na potrzeby przemysłu.
EN
The article presents various models of pedestrian crash test dummies, grouping them by their applicability: vehicle manufacture or road accident reconstruction. Selected experiments in the latter area using dummies of pedestrians are presented. The second part of the article is devoted to a description of a PRIMUS dummy - a relatively new product on the market. The structure of the dummy is presented, and studies verifying the dynamic response of the dummy in a collision with pedestrian are summarized. The application of the dummy in road accident reconstruction and R&D experiments are presented.
PL
W artykule omówiono kryteria biomechaniczne, które mogą być przydatne do ilościowej analizy obrażeń uczestników wypadków drogowych, m.in. w zakresie obrażeń głowy, szyi, klatki piersiowej oraz kończyn dolnych. Kryteria te wyznacza się na podstawie analizy charakterystyk czasowych przyspieszenia, prędkości, przemieszczeń, a także sił i momentów sił (różne w zależności od rodzaju wskaźnika). Omówienie kryteriów przeprowadzono w oparciu o przykładowe obowiązujące w Europie normy z zakresu bezpieczeństwa, m.in. Regulamin 80 EKG/ONZ (dotyczący testów zderzeniowych w pojazdach M2, M3), Regulamin 129 (dotyczący testów fotelików dziecięcych) oraz normy brytyjskiej GMRT2100 (dotyczącej bezpieczeństwa pasażerów w transporcie kolejowym). Uwzględniono również wyniki własnych badań symulacyjnych. Niektóre z przedstawionych wskaźników oceny obrażeń zostaną zaimplementowane do wielobryłowego modelu ciała człowieka w programie V-SIM.
EN
The article discusses the biomechanical criteria that may be useful in the quantitative analysis of injuries to road accident participants, e.g. in terms of head, neck, chest, femur and tibia injuries. These criteria are determined on the basis of the analysis of the time characteristics of acceleration, velocity, displacement, as well as forces and moments of forces (different depending on the type of indicator). The discussion of the criteria in this article is based on examples of safety standards in force in Europe, including Regulation 80 of the UN/ECE concerning crash tests in M2, M3 vehicles, Regulation 129 concerning the tests of child seats and the British standard GMRT2100 concerning the safety of passengers in rail transport. The results of simulation tests done by the author of the article were also taken into account. Some of the injury assessment indicators presented will be implemented into the MULTIBODY human body model in the V-SIM program.
EN
The symmetry of feet loading and adequate postural control are crucial aspects of proper squat performance. The study aimed to evaluate the effect of various stance widths during squat on postural control and symmetry of feet loading. Methods: Thirty healthy individuals participated in this study. Each participant performed one type of squat with a narrow stance (NS), hip stance (HS) and wide stance (WS). Results: A significantly higher value of CoP path length, the velocity of sways and Area95 were obtained for the WS squat compared to NS and HS. In addition, the wide feet setting significantly affected not only the feet loading symmetry but also the strategy (high LyE), the amount of irregularities (high SampEn) and the CoP time-series roughness complexity (high FD). It has been shown that as the base of support grew, the asymmetry index grew. Conclusions: The wide squat is less stable, requiring more complex postural control behavior and more flexibility. Performing this squat significantly shifts the pressure to the dominant limb.
EN
The aim of the current study was to examine the variation on the kinematic parameters in the basketball shot associated with the shooting distance. Methods: Twenty-seven female adolescent basketball players aged 12.1 ± 0.9 years completed 10 BS trials from a frontal position of 4.75 m and 5.75 m from the basket. Nine anatomical markers were placed on the participants’ dominant side to assess the kinematic variables. The following variables were analyzed: angle, velocity, and height at ball release; centre of mass horizontal displacement and maximum height attained; maximum hip height and hip height at release; shoulder, elbow, and knee angular position and velocity at ball release; deepest knee flexion during the preparatory phase; the peak of the angular velocity of the shoulder, elbow, and knee joints. Results: At release, the angle decreased while velocity increased significantly at 5.75 m. During the release, greater shoulder flexion and increased joint (shoulder and knee) angular velocity were observed. The deepest knee flexion and the centre of mass horizontal displacement were accentuated at 5.75 m. The ball release occurred before the peak of the jump phase. Conclusions: To compensate for the long ball trajectory to the basket, participants perform a set of adjustments in the body segmental organization to increase the ball velocity at release. The coaches’ feedback should focus on the shooting arm’s positioning and in the jump phase (to jump as close to vertical as possible). Also, a consistent shooting technique should be acquired close to the basket before expanding the shooting range.
EN
Purpose: The aim of this study was to develop a method to implement muscle forces to a numerical model of a dummy and to evaluate the effect of muscle activation on driver behavior during a frontal collision. The authors focused on the forces acting at the knee, hip, and elbow joints. Methods: The authors carried out torque measurements in joints using the Biodex System 4. Then, the previously developed numerical models were modified by introducing the joint torque values. Moments of force were introduced as a function of the rotation angle. During research, numerical simulations were carried out in three stages: in the first stage, a full vehicle crash was analyzed to determine the change of velocity of the vehicle interior; in the second stage, subsidence of the system was realized; in the third stage, a frontal crash was simulated. The models considered the operation of the sensors, airbag and seat belt tensioning system. Results: A numerical model with the active response of the dummy to the change in position during impact was developed. The results of the dynamic analysis were used to analyze the impact of muscle activation on dummy behavior. The change in shoulders rotation angle, the lateral and vertical displacement of the dummy’s center of gravity, and the forces acting between the dummy and the seat belt were compared. Conclusions: The effect of muscle action on the behavior of a dummy during a frontal collision was determined.
EN
Purpose: The research aimed to assess the influence of vibration therapy on acceleration of muscles regeneration process after physical effort. Verification of the pace of motor capabilities recovery in fatigued muscles was performed with the use of the measurement method applying shear-wave elastography. It took into account an alteration in muscle stiffness affected by created passive stresses and accompanying deformations connected with muscles work above their resting length. Methods: The research included 42 young males aged 20–24. They all were a homogeneous group regarding body build indices (body height 175.4 ± 8.1 cm; body mass 75.5 ± 8.32 kg) and the level of physical activity. Muscles of lower limbs (hip and knee joints extensors and flexors plantaris) were subject to submaximal exercise of the auxotonic muscle work character after a 90 s warm-up. The exercise comprised 20-fold overcoming the load at the level of 75% of maximal strength abilities without rest, by alternating between extension and flexion of lower limbs joints at the leg press placed at 45° angle upward and monitoring of angle setting of lower limbs joints. The post-exercise restitution used a vibration stimulus of variable frequency ranging from 20 to 50 Hz and amplitude of 0.5 mm, and passive resting in the control group. For an objective assessment of the applied vibration effect, a 5-fold measurement of rectus femoris muscles stiffness of both limbs at the middle of venter took place after each stage of the experiment. Results: After warm-up, a considerable increase of the examined muscles stiffness, that did not vary significantly, was observed. In the DW experimental group (vibration massage), where post-exercise restitution was enhanced by vibration, significantly lower values of muscle stiffness were registered after each of the post-exercise regeneration stages in relation to the DB control group (passive rest). After the I regeneration stage, a value of the Δ σ _r1-s variable ( p < 0.05) lower by 16% was noticed in favour of the group enhanced by vibration. Whereas, values of muscles stiffness after the II stage of regeneration, Δ σ _r2-s were by 14% lower in favour of DW group ( p < 0.005). Conclusions: Enhancement of the post-exercise relaxation of muscles by vibration treatment significantly lowered the values of post-exercise muscles stiffness and turned out to be a more effective method of restitution than passive resting. Recovery of the level of muscles stiffness from before the exercise was much slower in the control group than in the one enhanced by vibration. The improved method of muscle stiffness measurement with the use of shear-wave elastography with a special head attachment turned out to be a useful tool to assess post-exercise muscles restitution.
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EN
In the study, wave propagation along aorta is studied for different normal and pathological conditions in distal arteries. The mathematical model is based on the axisymmetric incompressible Navier-Stokes equations for blood and momentum equations for an incompressible viscoelastic arterial wall. The solution has been found as a superposition of forward and backward running waves. The blood pressure and flow curves measured by ultrasound in larger systemic arteries of ten healthy volunteers have been used for identification of the model parameters. It is shown that individual geometry plays an essential role in the location of positive and negative wave reflection sites along the aorta and, thus, in the pressure and flow patterns as well as blood distribution into the side branches. The model is validated by comparative study with the same dependencies computed previously on a 55-tube model as well as on the measurement data. The model can be used for determination of the individual parameters for patient-specific cardiovascular models and further in silico modeling of the outcomes of surgical and therapeutic procedures.
EN
Implantation of synthetic meshes provokes complications which require long-lasting follow-up. The mesh materials exposed to physiological conditions demonstrate differences in failure load, stiffness and extension. Mechanical alterations of explants made of polyester were investigated using a uni-axial tensile test and a relaxation test. The tensile strength of the explanted meshes changed in the transversal direction. The elastic modulus in the same direction increased two times. A magnified mesh image displayed mesh alteration. The relaxation tests revealed that the initial stress decreases after implantation while the reduction of stress increases in the interval 50%-96.6%.
EN
Multiscale in silico modeling of the cell-tissue-organ units is an emerging area of research with the potential to improve our understanding of various disease pathogenesis. Using a multiscale modeling approach, we developed a computational model of the human cornea to investigate how the application of macroscale loads may alter the micro-mechanical environment of the cells. We then utilized the multiscale model to study the effect of physiological and non-physiological mechanical loading conditions such as intraocular pressure (IOP) loading, IOP spike, and eye-poking on the corneal cells. On comparing the results obtained under increased IOP and eye-poking loading, we observed large differences in the averaged principal stress magnitudes in the immediate vicinity of the cell through the thickness of the cornea. On the other hand, our model predicted that under physiological IOP loading, the average principal strain magnitudes in the immediate vicinity of the cell remained almost constant irrespective of the cell location in the stroma. To our knowledge, this is the first study that investigates the effect of mechanical loading on the corneal cells through a multiscale modeling framework. Our computational multiscale cornea model provides a platform to perform virtual experiments and test hypotheses to further our understanding of the potential mechanical cause of multiple diseases in the cornea.
PL
Deponowanie wyników badań naukowych - zarówno opracowanych, jak też tzw. surowych danych - odbywa się pod wieloma postaciami, poprzez zamieszczanie w repozytoriach danych badawczych, umieszczanie wyników w publikacjach, które są następnie indeksowane na platformach czasopism, w bazach bibliograficzno-abstraktowych Niektóre czasopisma funkcjonujące w obiegu międzynarodowym wymagają od autorów dołączania do artykułów także zbiorów z danymi, bądź zdeponowania ich w jednym z ogólnodostępnych repozytoriów danych badawczych. W artykule zaprezentowano wybrane bazy danych, dostarczających informacji o wynikach badań m.in. z zakresu biomechaniki, fizjologu, psychologii.
EN
Depositing scientific research results - both research and raw data - takes place in many forms, by depositing research data: in repositories, as results in publications, which are then indexed on publisher's platforms, and in bibliographic and abstract databases and informing about obtained results research. Some international journals require authors to attach data collections to their articles, or to deposit them in one of the publicly available research data repositories. The following publication is a presentation of selected databases providing information on research results, including in the field of biomechanics, physiology, psychology.
PL
Celem pracy była ocena stabilności posturalnej w różnych warunkach podparcia: stanie obunóż, jednonóż i w tandemie przy oczach otwartych. W badaniach wzięła udział grupa trzydziestu trzech zdrowych osób w wieku 21.88 ± 1.65 lat. Badania zostały przeprowadzone przy użyciu platformy AMTI AccuSway (30 sekund – każda próba). Do obliczeń eksportowano położenia środka nacisku stóp na podłoże (CoP) w płaszczyznach x i y. Następnie została policzona długość drogi CoP i współczynniki dynamiki nieliniowej: entropia próbkowa, wymiar fraktalny i wykładnik Lapunowa. Wykazano, że zmniejszenie pola powierzchni podparcia powoduje istotny wzrost współczynnika entropii próbkowej i wymiaru fraktalnego.
EN
The aim of the study was to assess postural stability under different base of support: both foot standing, one-leg standing and tandem with eyes open. A group of thirty-three healthy persons aged 21.88 ± 1.65 years participated in the study. The tests were carried out using the AMTI AccuSway platform. The locations of the center of foot pressure (CoP) in the X and Y planes were exported. Then the CoP path length and nonlinear dynamics coefficients were calculated: sample entropy, fractal dimension and Lapunov exponent. It has been shown that the reduction of the support surface area causes a significant increase in the sample entropy factor and the fractal dimension.
EN
Stroke-related hemiplegia is an important factor influencing parameters of gait. So far, limited papers have assessed temporo-spatial capabilities and their correlations with gait parameters in the early post-stroke stage. This pilot study evaluated the temporospatial parameters of gait and assessed the maximal isometric and isokinetic torque production of the plantar flexor and dorsiflexor muscles. Methods: 15 patients with lower limb spasticity and 15 healthy controls were included. Stroke severity was assessed using the Modified Ashworth Scale and the Barthel Index. Gait cadence, gait speed, and gait cycle were assessed using inertial sensors during a Timed Up and Go test. Maximal isometric and isokinetic torque production of the ankle plantar flexor and dorsiflexor muscles were assessed using an isokinetic dynamometer device. Results: Post-stroke patients had statistically significantly lower gait cadence than healthy participants (17%, p < 0.05). Statistically significantly lower values of vertical acceleration were also noted during a sit-to-stand movement task (42%, p < 0.05). Plantar flexion torque of the affected limb was significantly different during isometric (63%, p ≤ 0.01) and isokinetic work for 30o /s (49%, p = 0.04), 60o /s (58%, p = 0.01) and 20 °/s (53%, p = 0.01). Dorsiflexor muscles’ torque production was significantly different in isometric activity (38%, p = 0.04). A statistically significant positive correlation occurred between the absolute peak torque of the dorsiflexor muscles in both static and speed phases of gait (Rs = 0.65, p = 0.04). Conclusions: Despite the low intensity of spasticity and early phase after stroke, differences in the muscle torque production and temporo-spatial parameters, as well as the correlations between them, were noticeable.
EN
The aim of the study was to investigate the relationships between shuttlecock velocity during a badminton forehand smash with and without jump (VmaxWJ and VmaxNJ), strength of upper limb muscles, vertical jump height and to analyze differences in these parameters for each gender. Methods: The study examined members of the Polish National Badminton Team seven women and seven men. A special torque meter was used to assess the strength of the upper limb muscles. Vertical jumps were performed on an AMTI force plate. Shuttlecock velocity was measured using Vicon motion capture system. Results: Differences between the right and left limbs were observed in all muscle groups except shoulder flexion for both genders. The results of all measured parameters: torques, height of countermovement and spike jump (HACMJ, HCMJ, HSPJ), VmaxWJ and VmaxNJ, were greater for men than for women. No statistically significant differences were found between VmaxWJ (men: 83.27 ± 4.83 m/s; women: 67.57 ± 4.21 m/s) and VmaxNJ (men: 84.19 ± 6.05 m/s; women: 69.70 ± 6.53 m/s) within the same gender. Positive correlations were found between both HCMJ and HSPJ regarding VmaxWJ in men; the height of shuttlecock impact in jump smash (HWJ) and HSPJ in women; proving the importance of jumping ability in badminton. Negative correlations were found between HWJ and VmaxWJ for both genders. Conclusions: The jump before smash is not used in order to hit the shuttle from the highest point, but to gain time to correctly prepare the phase of stroke while being in the air.
EN
The treatment of comminuted fractures of distal humerus poses a challenge for orthopaedics. Previous studies assessing the global stiffness of the bone – stabilizer system – made it impossible to explicitly indicate an optimal configuration of the locking plates in the treatment of this kind of fractures. The aim of the present research was to comparatively analyze the stabilization conditions of intraarticular fractures of distal humerus with the use of various configurations of the stabilizer. Methods: The research was based on the analysis of mutual displacements of bone fragments. Such evaluation was performed with the use of numerical simulation conducted with the use of the finite element method. A realistic model of humerus was based on the CT data. Three spatial configurations of the stabilizer (parallel, posteromedial and posterolateral) were considered. The mutual displacements of bone fragments as well as the deformity of the stabilizer under various loading conditions were analyzed. Results: In most cases, the parallel setting of the plates ensures a better stabilization of the bone fragments than the perpendicular configuration. The most difficult conditions of stabilization were obtained for the lateral bone fragment. The value of the fragments’ displacements significantly increases for loading directions occurring with ascending flexion angle of the joint. Conclusions: In most cases, the parallel setting of the plates ensures a better stabilization of the bone fragments than the perpendicular configuration.
EN
The purpose of this research was to examine the impact of body composition on the anaerobic ability to generate strength and power produced separately by upper and lower limbs during dry-land and in-water (propulsion force) tests. Further examination included the influence of all gathered anaerobic strength indices on the results of 100-m front crawl race. Methods: The study involved 26 male swimmers (age: 19.8 ± 2.48 years). Fat-free mass, total body water and muscle mass of arms, legs, and trunk were measured. Dry-land average work, maximal power generated in 40-second arm-cranking test, and work generated in 20 countermovement jumps were evaluated. The forces generated separately by arms and legs were assessed during 40-second tethered swimming. All indices of body composition were found strongly correlated with indices of average work and maximal power generated by arms and legs in dryland tests. Results: Muscle mass of arms and trunk moderately and strongly (r = 0.44–0.64) influenced the force generated by arms in tethered swimming. There was no significance in the relationship of leg muscle mass and force generated by legs in tethered swimming. Significant relationships were observed between the results of the 100-m front crawl and the muscle mass of the arms, trunk, legs, as well as the average work and maximal power in the arm-cranking test (r: 0.39–0.54). The average impulse of arm force and maximal leg force in tethered swimming moderately and significantly correlated with 100-m swimming results. Conclusions: The study concludes the relevance of developing muscle mass balanced to the body size, which is involved in propulsion force production in sprint front crawl swimming.
EN
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.
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