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The altitude differential of the specific mechanical energy, diff (e$_{mech}$), is used to evaluate skiing performance. It is defined as the negative differential between the skier's total specific mechanical energy (e$_{mech}$) and the altitude of the skier's center of mass (COM). Till now, e$_{mech}$ was obtained upon a mass-point (MP) model of the skier's COM, which neither considered the segmental energies of their relative movements to the COM, nor their rotational kinetic energies. The aims of the study were therefore: (a) to examine the deviations in diff (e$_{mech}$) between the MP and a more complex linked segment (LS) skier model consisting of 15 rigid bodies, which encountered the aforementioned defectiveness, (b) to compare the energy fluctuations of the two skier models, and (c) to investigate the influence of the gate setup on (a) and (b) in giant slalom. Three-dimensional whole-body kinematics of nine skiers was measured using a global navigation satellite system and an inertial motion capture system while skiing on a predefined course divided into a turny and open gate setup. Mechanical energies including their altitude differentials were calculated for the LS and MP models. There were no significant differences in e$_{mech}$ and diff (e$_{mech}$) ski turn averages, as in individual data points, between both skier models for both analyzed gate setups. The energies additionally considered by the LS model presented a negligible part regardless of the gate setup. In conclusion, the MP skier model is sufficiently accurate for the evaluation of the skiing performance with diff (e$_{mech}$).

U ovome radu, cilj je analizirati biomehaniku tehnika u sportskim borilačkim kretnjama i time utvrditi mehanizme nastanka ozljeda u svrhu njihove prevencije. Za provedbu biomehaničke analize izabran je taekwondo, a provedena je na primjeru najčešće korištenog udarca u taekwondou, kružnog udarca. Opisuje se pravilno izvođenje tehnika uz osvrt na česte pogreške, a fokus je na koljenom zglobu zbog bitne uloge njegove anatomije u kretnjama i izloženosti ozljedama koje mogu dovesti i do trajnih, ozbiljnih oštećenja struktura u koljenu kao što su rupture ligamenata. Nakon osvrta na najčešće nepravilnosti kod izvođenja pokreta, detaljno se analizira svaki pojedini element ključan za pravilnu izvedbu kružnog udarca u cjelini. Pogreška u jednom elementu narušava kvalitetu cjelokupne izvedbe što s vremenom može dovesti do ozljeda. Iako su ozljede u svakom sportu, a posebno u borilačkim sportovima, neizbježne, potrebno ih je barem svesti na minimum, a to se, uz kvalitetno zagrijavanje i istezanje, postiže upravo temeljitim učenjem i uvježbavanjem te izvedbom pravilnih tehnika. In this paper, the goal is to analyze the biomechanics of sport techniques used in martial arts and to determine the mechanisms of injuries for the purpose of their prevention. Biomechanical analysis was performed on one of the most commonly used kick in taekwondo, the roundhouse kick. The proper execution of techniques is described along with common mistakes, and the focus is on the knee joint due to the essential role of its anatomy in movements and its exposure to injuries that can lead to permanent, serious damage to structures in the knee such as ruptured ligaments. After looking into the most common mistakes in movements, each individual element, crucial for the proper execution of the roundhouse kick as a whole, is analyzed in detail. A mistake in only one of the steps negatively affects the quality of the overall performance, which can eventually lead to injuries. Although, injuries are inevitable in every sport, and especially in martial arts, it is necessary to at least reduce them to a minimum, and this, along with effective warm-up and stretching, is achieved by learning, practicing and performing proper techniques.

Achondroplasija je skeletna displazija (displazija - abnormalni rast ili razvoj), također identificirana kao rijetka bolest kostiju. Achondroplasija je najčešći oblik hondrodisplazije i javlja se zbog mutacije u genu receptora faktora rasta fibroblasta 3 (FGFR3), koji kodira trans membranski receptor (protein koji se proteže kroz stanične membrane) koji je između ostalog važan u regulaciji linearnog rasta kostiju. Procjenjuje se da je njegova učestalost oko 1/25 000 živorođene djece diljem svijeta, a neke od karakterističnih kliničkih karakteristika, navedenih u nastavku, vidljive su pri rođenju: rhizomelia - nesrazmjer duljine proksimalnih dijelova tijela; pretjerana lumbalna lordoza - pretjerana zakrivljenost donjeg dijela leđa; brahidaktilija - kratkoća prstiju je u odnosu na duljinu drugih dugih kostiju i drugih dijelova tijela, šake su također široke, kratke i u obliku trozuba; makrocefalija i frontalna izbočina - neobično velika glava s istaknutim čelom; torakolumbalna kifoza - nastaje zbog mehaničkih čimbenika, posebno opće mišićne hipotonije koji, s malim udovima, malim vratom i velikom glavom, čine postizanje grubih motoričkih sposobnosti (većih pokreta) sporijim od tipičnog; genu varum – tjelesna je deformacija obilježena izvijanjem potkoljenice prema van u odnosu na natkoljenice. Većina zglobova može biti hiperekstenzibilna. Glavni cilj ovog završnog rada je prikazati biomehaničku procjenu posture kod osoba s achondroplasiom putem mjerenja. Achondroplasia is a skeletal dysplasia (dysplasia - abnormal growth or development), also identified as a rare bone disease. Achondroplasia is the most common form of chondrodysplasia and occurs due to mutations in the fibroblast growth factor receptor 3 (FGFR3) gene, encoding a transmembrane receptor (a protein that spans the membrane of cells) that is important in regulating linear bone growth, among other functions. It is estimated that its incidence is about 1/25,000 live births worldwide and some of the characteristic clinical features, listed below, are visible at birth: rhizomelia - disproportion of the length of the proximal limb; exaggerated lumbar lordosis - excessive curvature of the lower back; brachydactyly - the shortness of the fingers is relative to the length of other long bones and other parts of the body, the hands are also broad, short and trident shaped; macrocephaly and frontal bossing - is an unusually large head with a prominent forehead; thoracolumbar kyphosis - it is due to mechanical factors, specifically the general muscular hypotonia which, along with small limbs, small neck and large head, make achievement of gross motor skills (larger movements) slower than typical; genu varus - is a physical deformity marked by outward bowing of the lower leg in relation to the thighbow legs. Most joints can be hyperextensible. The main goal of this final paper is to show the biomechanical assessment of posture in people with achondroplasia through measurements and tests.

U ovom su radu na primjeru čučanja, pomoću dodirnog pritiska stopala i podloge, istražena statička opterećenja u koljenu za dvije pozicije mjerenja, na punom stopalu i na prstima. Mjerenja su provedena putem Tekscan platforme, a izmjereni podatci analizirali su se preko programskog paketa FootMat Research. U uvodnom dijelu rada razmatrana je anatomija i fiziologija koljenog zgloba te njegova biomehanika. Također, teorijski su opisani svi najvažniji dijelovi koljena. Nakon toga opisivani su uređaji za mjerenje i njihov način rada. Prije samog opisivanja mjerenja objašnjena je metoda izračunavanja opterećenja koljena. Nakon izmjerenih svih pozicija u eksperimentalnom dijelu rada, proveden je računski dio u kojem su uspoređene dobivene sile. In this paper, using the example of the squatting, through the contact pressure of the foot and the surface, the static loads in the knee were examined through two measurement positions, on the full foot and on the toes. The measurements were carried using Tekscan platform, and the measured data were analyzed using FootMat Research softwyre package. In the introductory part of the paper, the anatomy and physiology of the knee joint and its biomechanics will be discussed. Also, all of the most important parts of the knee are described. After that, begins the description of the measuring device and its mode of operation. Before describing the measurement itself, the method of calculating knee load is described. After all positions of the experimental part have been carried out, using described method the knee load is calculated and compared.

Introduction: Vertical jumps are the key components of performance in the classical ballet and volleyball. Asymmetry of performance between the lower extremities is a potential risk factor for injury. Purpose: The purpose of this study was to analyse the symmetry of the unilateral vertical countermovement jump (CMJ) in a group of female ballet dancers and in a group of female college volleyball players. Methods: We tested the CMJ with the dominant and nondominant leg and the bilateral CMJ among 15 female ballet dancers and 15 female volleyball players aged 18–24 years. Ground reaction forces were recorded with the force plate and five variables were analysed - jump height, power, energy, and time to flight and time to maximum force during landing. Results: 2 × 2 repeated measures of ANOVA indicates that type of sport is influencing some of the single leg CMJ variables (energy used and time to maximal force in landing), there was a significant asymmetry between dominant and non-dominant leg in some of the vertical CMJ variables (CMJ height, energy used and the average power was marginally significant). The interaction between the type of sport and leg dominance however was not significant for all of the analysed CMJ variables indicating no difference in asymmetry between the dominant and non-dominant leg in the two investigated sports. The results expressed in the percentage differences between both legs that is widely used in the scientific literature showed that ballet dancers exhibited more symmetrical CMJ height, power, and energy compared to volleyball players. The average percent difference in CMJ height between the dominant and non-dominant leg was 4.26 (10.60) % and 13.36 (14.72) %, respectively. On average, volleyball players jumped slightly higher at the bilateral CMJ (p < 0.001). Conclusion: Sport-specific training background could explain the observed contralateral deficit differences between two sport groups. The elements of ballet training could be introduced into the volleyball training to overcome observed this contralateral deficit. Nasl. z nasl. zaslona. Opis vira z dne 20. 9. 2022. Članek št.: 10669. Bibliografija: str. 5-6. Abstract.

Patellofemoral pain (PFP) is a frequent knee condition. The aim of this study was to investigate strength, flexibility and postural control in people with and without PFP. Fifty-five participants between 14 and 54 years of age (PFP = 18, control group = 37) were included. Strength and flexibility for all trunk, hip, knee and ankle muscle groups were measured along with postural control outcomes. Analyses were conducted based on the “affected” and “non-affected” leg within-group and between-groups. Between-groups analysis demonstrated a statistically lower strength of trunk muscles (range: 35.8–29.3%,p< 0.001), knee extensors (20.8%,p= 0.005) and knee flexors (17.4%,p= 0.020) in PFP participants. Within-group analysis proved an 8.7% (p= 0.018) greater hip internal rotation strength and ankle extension flexibility (p= 0.032) of the “affected side” in PFP participants. This was, to our knowledge, the first study to investigate the strength of all trunk muscle groups. The results indicate that participants with PFP exhibit impaired strength of trunk muscle groups, along with knee muscle deficits, which may present a rehabilitation target. Clinicians should consider implementing trunk strengthening exercises into PFP programs along with knee-targeting exercise programs.

Svrha: Glavni cilj studije je utvrditi postoji li povezanost između obrasca plantarnog pritiska stopala i uspješnosti u gađanju pištoljem. Metode: Trideset policijskih službenika specijalne policije (N = 30) Antiterorističke jedinice Lučko (prosječna dob 40 ± 6.5 godina, visina 180 ± 5.3 cm, težina 89.2 ± 8 kg) sudjelovalo je u testiranju prilikom gađanja u metu stojeći na platformi Zebris (FDM; GmbH München, Njemačka). Za izračun povezanosti između obrasca plantarnog pritiska stopala i uspješnosti gađanja, koristio se Spearmanov koeficijent korelacije (r). Rezultati: Preciznost gađanja je značajno negativno povezana s vršnim silama stražnjeg (desnog) stopala (pete; N, r = - 0.19, p < 0.001). Kada se vršna sila normalizira za tjelesnu masu (N/kg), preciznost gađanja ostaje negativno povezana s vršnim silama stražnjeg (desnog) stopala (pete; r = - 0.17, p < 0.001). Preciznost gađanja je pozitivno povezana s postotkom relativne sile stražnjeg (desnog) stopala (prstiju; r = 0.11, p < 0.05) te je negativno povezana s relativnim silama stražnjeg (desnog) stopala (pete; r = - 0.11, p < 0.05). Varijable koje statistički značajno povezane s preciznosti u gađanju (r = 0.18, r2 = 3%, f = 4.765, p = 0.009) su vršne sile pete desnog stopala (b = - 0.35, t = - 2.435, p = 0.015) i relativne sile pete desnog stopala (b = 0.01, t = 0.822, p = 0.412, koja nije značajna). Zaključak: Ovim istraživanjem se može potvrditi statistički značajna uloga stražnje (desne) noge u korelaciji s preciznošću u gađanju iz pištolja. Što su relativne sile (%) stražnjeg (desnog) stopala ispod pete više, to će preciznost u gađanju biti manja, a što su relativne sile stražnjeg (desnog) stopala ispod prstiju više, to će preciznost u gađanju biti veća, dok je prednja (lijeva) noga pasivna i podjednako oslonjena na površinu prednjim i stražnjim dijelom stopala. Purpose: The main objective of the study is to determine if there is a correlation between plantar pressure distribution pattern of a foot and the efficiency in pistol shooting. Methods: Thirty police officers (N = 30), members of the Antiterrorist unit Lučko (of average age 40 ± 6.5, height 180 ± 5.3 cm and weight 89.2 ± 8 kg) were tested while standing on the Zebris platform (FDM; GmbH München, Germany) and shooting at the target. Spearman’s coefficient was used to calculate the correlation between plantar pressure distribution pattern of a foot and the efficiency in pistol shooting. Results: Shooting precision is significantly negatively related to the peak forces of the right back foot (heel; N, r = - 0.19, p < 0.001). When the foot force is normalized with the body mass (N/kg), shooting precision remains negatively connected with the right back foot force (heel; r = - 0.17, p < 0.001). Shooting precision is positively related to the percentage of the average right forefoot force (toes; r = 0.11, p < 0.05), as well as it is negatively related to the average right back foot force of the (heel; r = - 0.11, p < 0.05). Variables significantly correlated with pistol shooting are Correlation of the statistically important variables (r = 0.18, r2 = 3%, f = 4.765, p = 0.009) peak right back foot force of the heel (b = - 0.35, t =-2.435, p = 0.015) and variable of the average right back foot force of the heel (b = 0.01, t = 0.822, p = 0.412, which is not significant). Conclusion: This study confirms a significant role of the right leg in the correlation with the precision of the pistol shooting. When average right back foot forces beneath the heel expressed in percentage are higher, the shooting precision will be more inaccurate, whereas when average right forefoot forces beneath the toes are higher, the shooting precision will be higher as well.

The two-point force-velocity model allows the assessment of the muscle mechanical capacities in fast, almost fatigue-free conditions. The aim of this study was to investigate the concurrent validity of the two-point parameters with directly measured force and power and to examine the generalization of the two-point parameters across the different functional movement tests of leg muscles. Twelve physically active participants were tested performing three functional lower limb maximal tests under two different magnitudes of loads: countermovement jumps, maximal cycling sprint, and maximal force under isokinetic conditions of the knee extensors. The results showed that all values from the two-point model were higher than the values from the standard tests (p &lt, 0.05). We also found strong correlations between the same variables from different tests (r &ge, 0.84, p &lt, 0.01), except for force in maximal cycling sprint, where it was low and negligible (r = &minus, 0.24). The results regarding our second aim showed that the correlation coefficients between the same two-point parameters of different lower limb tests ranged from moderate to strong (r &minus, 0.47 to 0.72). In particular, the relationships were stronger between power variables than between force variables and somewhat stronger between standard tests and two-point parameters. We can conclude that mechanical capacities of the leg muscles can be partially generalized between different functional tests.

Racket sports such as padel are characterized by the repetition of unilateral gestures, which can lead to negative adaptations like asymmetries or overuse musculoskeletal injuries. The purpose of this study was to determine the differences in ball impact positions (i.e., forward or backward of the center of gravity) in nine stroke types in a sample of forty-eight recreational male padel players. The sample included 14,478 shots corresponding to 18 matches from six tournaments. Forty-eight male padel players were classified into two groups according to their level: trained (n = 24) and novice (n = 24). Type of stroke and ball impact position were registered using a computerized motion tracking video system. The ball impact position was computed from the distance (cm) between the coordinates of the ball and the player’s center of gravity. Results show that trained players hit the ball in a more backward position (from 11 to 25 cm, compared to novice) in serve and offensive strokes (volleys, trays, and smashes) but used more forward strokes (from 7 to 32 cm, compared to novice) in defensive shots (groundstrokes, wall strokes, and lobs). Because the current differential variables are trainable and demonstrated to be of relevance for performance, the findings of this study may assist padel coaches in designing proper training plans to improve effectiveness and to prevent musculoskeletal injuries regarding the type of stroke and ball impact position. Such knowledge may constitute a very important factor affecting technique, biomechanics, and injury management in padel players of different competitive levels.

Tema ovog završnog rada je biomehanika koljenastog zgloba i analiza hoda te kako nam sama analiza hoda može pomoći pri prevenciji i otkrivanju ozljeda i nepravilnosti u koljenastom zglobu. U početku rada detaljno je opisana anatomija koljenastog zgloba kako bi se lakše moglo razumjeti koji sve mišići i kosti sudjeluju pri hodu i radu samog koljena. Opisana su mehanička svojstva zglobova te sveobuhvatna biomehanička analiza koljenastog zgloba, koja može pobliže razjasniti pokrete koljena pri hodu i sportskim aktivnostima. S druge strane postupkom pedobarografije, koja je provedena putem Zebris sustava, analizirani su parametri hoda u statičkom i dinamičkom mjerenju. U posljednjem poglavlju opisane su najčešće deformacije koljenastog zgloba i stopala te njihov utjecaj na hod i svakodnevni život čovjeka. Na kraju rada donesen je zaključak o biomehaničkoj analizi koljenastog zgloba i analizi hoda te kako se iste međusobno nadopunjuju.

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 Colin Jackson of Great Britain (12.91 s world record was set in 1994) and Dayron Robles of Cuba (12.87 s world record was set in 2008), two world record holders. Despite the athletes having performed at different times, we used comparable biomechanical diagnostic technology for both hurdlers. Biomechanical measurements for both were performed by the Laboratory for Movement Control of the Institute of Sport, Faculty of Sport in Ljubljana. A three-dimensional video analysis of the fifth hurdle clearance technique was used. High standards of biomechanical measurements were taken into account, thus ensuring the high objectivity of the obtained results. The following program was used: the ARIEL kinematic program (Ariel Dynamics Inc., Trabuco Canyon, CA, USA). The results of the comparative analysis found minimal differences between the two athletes, which was expected given their excellence. Dayron Robles’s hurdle clearance was more effective, as it was characterized by a smaller loss of horizontal center of mass (COM) velocity. 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. Colin Jackson completed the hurdle clearance slightly slower, as it took him 0.54 s. Jackson’s take-off phase also lasted 0.10 s, his flight phase 0.36 s, and his landing 0.08 s. The two athletes are quite different in their morphological constitution. Dayron Robles is 10 cm taller than Colin Jackson, resulting in a lower flight parabola of CM during hurdle clearance of the Cuban athlete. Dayron Robles has a more effective hurdle clearance technique compared to Jackson’s achievement. It can be considered that their individual techniques of overcoming the hurdle, reached their individual highest efficiency at this time.

Uvod: Zdravstveni delavci se pri svojem delu srečujemo s številnimi okvarami mišično-skeletnega sistema. Kolenski sklep je osrednji in največji sklep spodnjega uda, ki ima kompleksno anatomsko sestavo in pred seboj eno od najmočnejših mišic v telesu, m. quadriceps femoris. Sklep ima pomembno vlogo ne le pri gibanju (hoji, teku itd.), temveč tudi v mirovanju ter pri vzdrževanju pokončne drže, ko se sile teže preko sklepa prenašajo na podlago in obratno. Zaradi velikih obremenitev so poškodbe kolenskega sklepa pogoste. Zato je za ustrezno obravnavo poškodb in rehabilitacijo bistveno razumevanje anatomskih značilnosti, biomehanike sklepa in delovanja mišic nanj. Namen: Namen diplomskega dela je pregled slovenske in mednarodne literature, ki vključuje opis biomehanike kolenskega sklepa in delovanja posameznih mišic na sklep. Metode dela: V diplomskem delu je predstavljena literatura, izbrana iz podatkovnih baz neglede na leto izdaje in dostopna prek spleta: CINAHL, Cochrane Library, MEDLINE, PubMed, Google Učenjak. Iskanje knjižnih virov je bilo izvedeno v slovenskem knjižničnem informacijskem sistemu – COBISS.SI. Literatura je bila izbrana s pomočjo ključnih besed ali besednih zvez v slovenskem in angleškem jeziku. Rezultati in razprava: Kolenski sklep je kombinacija tečajastega in čepastega sklepa, prevladujoča giba sta fleksija in ekstenzija, v manjšem obsegu pa so možni še: notranja in zunanja aksialna rotacija, anteroposteriorna translacija ter addukcija in abdukcija. Mišice, ki delujejo na sklep, delimo na ekstenzorje in fleksorje. Glavni ekstenzor sklepa je mišica quadriceps femoris na sprednji strani stegna, ki jo tvorijo štiri mišice (rectus femoris, vastus medialis, vastus intermedius, vastus lateralis). Glavni fleksorji kolenskega sklepa so mišice na zadnji strani stegna (biceps femoris, semimembranosus, semitendinosus), ki so hkrati ekstenzorji kolčnega sklepa. Šibkejši fleksorji so še mišice sartorius iz sprednje skupine in gracilis iz medialne skupine stegenskih mišic ter mišici popliteus in gastrocnemius iz posteriorne golenske skupine. Fleksorji so odgovorni tudi za aksialno rotacijo v kolenskem sklepu. Navedene mišice so obenem tudi pomembni dinamični stabilizatorji sklepa. Zaključek: Mišice kolenskega sklepa so pomembne pri biomehaniki sklepa. Poleg vloge generatorjev moči za premikanje kosti in izvajanje gibov v sklepu, potrebnih pri vsakodnevnih dejavnostih, opravljajo ob pasivnih stabilizatorjih (meniskih, sklepnih vezeh in ovojnici) še vlogo dinamičnih stabilizatorjev sklepov. Introduction: Healthcare professionals often deal with musculoskeletal disorders. The knee joint is the intermediate and the largest joint of the lower limb which has a complex anatomical structure and one of the most powerful muscles, m. quadriceps femoris, located in front of it. The joint has an important role not only when performing various types of movement (e.g., walking, running, etc.), but also while resting and maintaining upright posture when body weight forces are being transmitted to the ground and vice versa. Due to heavy loading, the knee joint injuries are common. Therefore, it is necessary to understand its anatomical properties, knee joint biomechanics and muscle activity for a proper injury treatment and rehabilitation. Purpose: The aim of diploma work is to review the available academic literature regarding the knee joint biomechanics and muscle activity on the joint in Slovene and English language. Methods: The data presented in diploma work were collected from different online databases, regardless the date of publication: CINAHL, Cochrane Library, MEDLINE, PubMed, Google Učenjak. Slovenian Library Information System (COBISS.SI) was used to search for reference sources, using keywords and phrases in Slovene and English. Results and discussion: The knee joint is a combination of hinge and trochoid joints, its dominant movements are flexion and extension, whereas limited internal and external axial rotation, anteroposterior translation and adduction-abduction are possible as well. Muscles acting upon the knee joint are generally divided into extensors and flexors, according to their function. The main extensor is the anterior thigh muscle quadriceps femoris, which is composed of four muscles (rectus femoris, vastus medialis, vastus intermedius, vastus lateralis). The main flexors are the posterior thigh muscles (biceps femoris, semimembranosus, semitendinosus), which are also the extensors of the hip joint. Weak flexors are the anterior thigh muscle sartorius, medial thigh muscle gracilis, and two posterior crural muscles, popliteus and gastrocnemius. The flexors are responsible for axial rotation in the knee joint. These muscles are also important dynamic stabilizers of the knee joint. Conclusion: The knee joint muscles are important for the joint biomechanics. They act as power generators, which produce bone movement in the joint, necessary for everyday activities, and are important dynamic stabilizers of the joint as well, acting together with the passive joint stabilizers (menisci, ligaments, and joint capsule).

U ovom završnom radu obrađena je teorijska analiza kao i numerički dio koji se odnose na ravne pune sastavljene nosače. U prvim poglavljima su opisane neke osnovne relacije, fizikalne veličine i principi međudjelovanja kako bi se što jednostavnije shvatila daljnja razmatranja. U narednim poglavljima pažnja je posvećena određivanju reakcija veza u osloncima nosača kao i reaktivnih momenata, konstrukciji dijagrama poprečnih sila i momenata savijanja. Teorijskom analizom su prikazana razmatranja djelovanja fizikalnih veličina na nosač, uz jedan direktni proračunski primjer koji je to poglavlje povezao u cjelinu. U četvrtom poglavlju je dodana biomehanička razrada problema kao nešto što bi ovaj rad trebalo „začiniti“, ali i prikazano kako se uz malo mašte, znanja i idealizacije pojedini dijelovi ljudskog tijela u određenim trenucima mogu zamijeniti sa ravnim nosačima. Potom smo sa inženjerskog aspekta promatrali što se u cijeloj priči odvija paralelno sa zakonima definiranim u medicini i sportu., In this bachelor thesis is processed theoretical analysis as well as numerical part which are related to plain full assembled beams. In the first chapters are described some basic relations, physical labels and principles of interaction in order to understand further consideration as easy as possible. In further chapters attention is dedicated to how to get connection reactions in supports of beams as well as reaction torques, construction of diagrams associated with transverse forces and bending torque. In theoretical analysis are shown considerations of actions of physical labels on the beam, with one direct example of calculation which connected that chapter in one unit. In the fourth chapter has been added biomechanical elaboration of problem as something that need to „spice it up“ a little bit, and shown how we can with a little bit of imagination, knowledge and some sort of idealizations individual parts of human body in some moments replace it with plain beams. Then we are from engineering point of view observed what was going on throught the story in a parallel way with the medicine and sports.

Alpine skiing, both recreational and competitive, is associated with high rates of injury. Numerous studies have shown that occupational exposure to whole-body vibrations is strongly related to lower back pain and some suggest that, in particular, vibrations of lower frequencies could lead to overuse injuries of the back in connection with alpine ski racing. However, it is not yet known which forms of skiing involve stronger vibrations and whether these exceed safety thresholds set by existing standards and directives. Therefore, this study was designed to examine whole-body vibrations connected with different types of skiing and the associated potential risk of developing low back pain. Eight highly skilled ski instructors, all former competitive ski racers and equipped with five accelerometers and a Global Satellite Navigation System to measure vibrations and speed, respectively, performed six different forms of skiing: straight running, plowing, snow-plow swinging, basic swinging, short swinging, and carved turns. To estimate exposure to periodic, random and transient vibrations the power spectrum density (PSD) and standard ISO 2631-1:1997 parameters [i.e., the weighted root-mean-square acceleration (RMS), crest factor, maximum transient vibration value and the fourth-power vibration dose value (VDV)] were calculated. Ground reaction forces were estimated from data provided by accelerometers attached to the pelvis. The major novel findings were that all of the forms of skiing tested produced whole-body vibrations, with highest PSD values of 1.5–8 Hz. Intensified PSD between 8.5 and 35 Hz was observed only when skidding was involved. The RMS values for 10 min of short swinging or carved turns, as well as all 10-min equivalent VDV values exceeded the limits set by European Directive 2002/44/EC for health and safety. Thus, whole-body vibrations, particularly in connection with high ground reaction forces, contribute to a high risk for low back pain among active alpine skiers.

Critical traffic situations, such as vehicle collisions and emergency manoeuvres, can cause an occupant to respond with reflex and voluntary actions. These affect the occupant&rsquo, s position and dynamic loading during interactions with the vehicle&rsquo, s restraints, possibly compromising their protective function. Electromyography (EMG) is a commonly used method for measuring active muscle response and can also provide input parameters for computer simulations with models of the human body. The recently introduced muscle-contraction (MC) sensor is a wearable device with a piezo-resistive element for measuring the force of an indenting tip pressing against the surface of the body. The study aimed to compare how data collected simultaneously with EMG, video motion capture, and the novel MC sensor are related to neck-muscle loading. Sled tests with low-severity frontal impacts were conducted, assuming two different awareness conditions for seated volunteers. The activity of the upper trapezius muscle was measured using surface EMG and MC sensors. The neck-muscle load F was estimated from an inverse dynamics analysis of the head&rsquo, s motion captured in the sagittal plane. The volunteers&rsquo, response to impact was predominantly reflexive, with significantly shorter onset latencies and more bracing observed when the volunteers were aware of the impact. Cross-correlations between the EMG and MC, EMG and F, and F and MC data were not changed significantly by the awareness conditions. The MC signal was strongly correlated (r = 0.89) with the neck-muscle loading F in the aware and unaware conditions, while the mean &Delta, F-MC delays were 21.0 &plusmn, 15.1 ms and 14.6 &plusmn, 12.4 ms, respectively. With the MC sensor enabling a consistent measurement-based estimation of the muscle loading, the simultaneous acquisition of EMG and MC signals improves the assessment of the reflex and voluntary responses of a vehicle&rsquo, s occupant subjected to low-severity loading.

Predviđanje rupture te optimalno vrijeme kirurške intervencije aneurizme abdominalne aorte ostaje nedovoljno istraženo nakon desetljeća kliničkih, histoloških i numeričkih istraživanja. Iako postoje studije koje procjenjuju opasnost rupture aneurizme na temelju geometrijskih značajki dobivenih iz CT snimaka, one se još uvijek ne koriste u praksi. Korištenje numeričke analize za svakog pojedinog pacijenta uvodi previše pretpostavki o strukturi stijenke da bi se RPI (eng. rupture potential index) mogao smatrati pouzdanim. Numerički model G&R (eng. growth and remodeling) pomaže ukloniti nepotrebne pretpostavke te predstavlja najveći potencijal za računanje naprezanja, RPI-ja te nam pomaže detaljnije shvatiti samu rupturu. Funkcija razgradnje elastina jedan je od glavnih čimbenika koji određuju idealizirani oblik aneurizme. Koristeći stotinu različitih kombinacija parametara koji definiraju morfologiju aneurizme (parametri funkcije razgradnje elastina, predistezanja kolagena te početni promjeri zdrave aorte), istražen je odnos između morfologije aneurizme i RPI-ja te su uspoređeni numerički rezultati s kliničkim ispitivanjima.

Cilj rada usmjeren je na utvrđivanje razlika u kinematičkim parametrima šutiranja sa različitih pozicija. Značajna razlika utvrđena je u parametrima kut upada lopte u koš i trajanje šuta. U ostalim promatranim parametrima nije dobivena statistička značajnost razlika.

Pri raziskavah, ki so se ukvarjale z uporabo MC senzorjev za merjenje obremenitve človeških mišic, se je večkrat pojavilo vprašanje vpliva različnih karakteristik merjencev na rezultate meritev. Poznavanje vpliva različnih merjencev bi dodalo vrednost in razširilo možnost uporabe senzorja. Za raziskavo smo uporabili poenostavljen model mišice, ki smo ga kontrolirano raztegovali ter na njem hkrati spremljali izmerjene vrednosti MC senzorja in vzdolžno obremenitev raztega. Potrdili smo zelo visoko linearno korelacijo izmerjenih vrednosti in v drugem delu analize ugotovili blag vpliv različnega materiala merjenca. Past studies that used the MC sensor for measuring muscle load left unanswered the questions of the influence of different characteristics of measured human tissue. Knowing more about the influence of measured materials could add value and widen the field of research with the MC sensor. For our research, we used a simplified model of the muscle, which was dynamically stretched in a controlled manner while simultaneously measuring the actual longitudinal force and MC sensor load. We confirmed very strong linear correlation between the two values and in the second part of analysis found small influence of different measured materials.