Tehnika i taktika odbojke na pijesku: usporedba karakteristika igre muškaraca i žena

The aim of the study was to compare the playing characteristics of male and female athletes in professional beach volleyball. Video material, including 15 matches from the women’s and 14 matches from the men’s Grand Slam in Klagenfurt 2005, was analysed with the game analysis software “Statshot”. Applied technique, position, quality, direction and movement behaviour of athletes were evaluated. By analysing every action of the six basic beach volleyball elements - serve, reception, setting, attack, block and defence - it was possible to gain complete game statistics. The comparison indicated that male and female top players apply different techniques for success. Chi-square tests were used to evaluate significant differences between genders. The differences in distributions of applied techniques were significant for all six elements: service (p<.01), reception (p<.05), setting (p<.01), attack (p<.01), block (p<.01) and defence (p<.01). Concerning quality distribution, statistical significance was found only within the elements serve and attack. Tactical considerations and gender-specific differences in anthropometry and physiology may be reasons for the different approaches.Uvod Dosadašnja istraživanja u odbojci na pijesku orijentirala su se na utvrđivanje razlika između pobjedničkih i poraženih ekipa, na učinke promjena pravila igre i opće karakteristike igre (vremensku strukturu, tehniku, taktiku i fizičke zahtjeve). Razlike u igri između muškaraca i žena mogle su se vidjeti u tim istraživanjima, ali nisu bile identificirane. Cilj je ovog istraživanja fokusirati se upravo na spolne razlike u igri profesionalnih igrača i igračica odbojke na pijesku. Pretpostavka za istraživanje bila je da će se razlike u antropometrijskim karakteristikama i fizičkim sposobnostima između dva spola, kao i visina mreže (2.24 za žene i 2.43 m za muškarce) na igralištu istih dimenzija (8 x 16 m) odraziti i na samu igru. Metode Video materijal, koji je uključivao 15 susreta sa ženskog i 14 susreta s muškog turnira Grand Slam u Klagenfurtu, održanom 2005. godine, analiziran je programom za analizu igre pod nazivom "Statshot". Kamera je bila postavljena oko 9 m iza osnovne linije i 7 m iznad terena. Vrednovale su se korištene tehnike, pozicije, kvaliteta izvedbe te smjer i način kretanja sportaša i sportašica. Analizom akcija svakog od šest osnovnih elemenata odbojke na pijesku: servisa, prijema, dizanja, napada, blokiranja i obrane bilo je moguće dobiti kompletnu statistiku igre. Ukupno su kod muškaraca analizirane 7393 akcije, dok je kod žena analizirano ukupno 7776 akcija. Kvaliteta izvedbe svakog elementa bila je procijenjena skalom od 4 ocjene. Kvalitetni igrači odbojke na pijesku, osposobljeni za rad s programom, vrednovali su kvalitetu izvedbe. Pouzdanost i objektivnost mjernog instrumenta procijenjeni su na uzorku od 100 akcija putem Scottova p-koeficijenta, a iznosili su .93, odnosno .90. Detaljan opis testova može se vidjeti u Tilp i sur., 2006. Rezultati Usporedba je pokazala kako se muški i ženski vrhunski igrači odbojke na pijesku razlikuju po primjeni tehničkih elementa u igri. Za utvrđivanje značajnosti razlika između spolova u primjeni tehničkih elemenata koristio se hi-kvadrat test. Razlike u distribucijama primijenjenih tehničkih elemenata bile su značajne za 6 elemenata: servis (p<.01), primanje (p<.05), dizanje (p<.01), napad (p<.01), blok (p<.01) i obrana (p<.01). Statistička značajnost razlika u kvaliteti izvedbe pojedinih elemenata utvrđena je samo u varijablama servis i napad. Rezultati su pokazali da muškarci i žene preferiraju različite tehničke elemente za početak poena. Približno polovina (47%) svih analiziranih servisa u muškoj konkurenciji bili su skok servisi. Naprotiv, u ženskoj konkurenciji zabilježeno je 48% ravnih servisa bez skoka, iako je skok servis zabilježen kao najuspješniji servis i u muškaraca i u žena u smislu izravnog poena (muškarci 5% i žene 9%). Rezultati ovog istraživanja pokazuju da su tehnike prijema podjednako kvantitativno raspoređene i u muškaraca i u žena. I jedni i drugi uspješno su izveli više od 50% prijema lopte (žene 55% i muškarci 60%). Velika razlika zabilježena je u tehničkim elementima koji pripadaju pripremi poena. Muškarci se koriste tehnikom dizanja čekićem i vršnom tehnikom u jednakom omjeru (46% svaki), dok je žene ipak preferiraju tehnike dizanja čekićem (84%) u odnosu na vršnu tehniku (9%). Analizom faze napada potvrđeni su očekivani rezultati da muškarci vole završavati napade smečiranjem (59%). Dok je u muškoj konkurenciji odigrano 41% plasiranih udaraca, u ženskoj je konkurenciji zabilježeno 50% plasiranih udaraca i 50% smečeva. Distribucija kvalitete za fazu napada pokazala je statistički značajnu razliku između muškaraca i žena (p<.01). Strategiju bloka u muškaraca karakterizira 88% dinamičnih akcija na mreži, dok se žene odmiču od mreže u 27% zabilježenih situacija u bloku te zauzimaju obrambenu poziciju duboko u samom terenu. Zabilježeno je i da su odbojkašice uspješno obranile više napada koji su izvedeni plasiranjem (46%) dok su se manje morale braniti od napada smečiranjem (35%). Takva razlika u uspješnosti u fazi obrane nije vidljiva i u odbojkaša koji su podjednako uspješno branili napade plasiranjem (38%) i napade smečiranjem (40%). Diskusija i zaključci Rezultati ovog istraživanja pokazuju da žene koriste drugačiju strategiju igre nego muškarci, profesionalne igračice i igrači u međunarodnoj odbojci na pijesku. Razlike su osobito naglašene u kvantitativnoj distribuciji korištenih tehničkih elemenata. Najveća razlike između spolova zabilježena je u omjeru dizanja izvedenih vršnom tehniko, koji su muškarci koristili 46%, a žene 9% u fazi postavljanja napada. Ovaj rezultat je vrlo zanimljiv i zapanjujući budući da su odbojkaški stručnjaci uvjereni da je ova tehnika odigravanja najpreciznija. Zanimljiv je i podatak da odbojkašice kad izvode početni udarac, izvode tek 20% skok-servisa iako njime postižu više izravnih bodova, u čemu su identične s odbojkašima. Razlozi različitih pristupa igri vjerojatno leže u taktičkim zamislima te spolnim razlikama koje se očituju u antropometriji i fiziologiji odbojkašica i odbojkaša. Budućim istraživanjima potrebno je utvrditi razloge i motiviranost za takav način ponašanja u igri

The acute time course of muscle and tendon tissue changes following one minute of static stretching

The purpose of this study was to investigate the time course of the changes of various muscle and tendon mechanical properties and the function responses of the plantar flexor muscles following 1 min of static stretching.Twenty-five healthy volunteers were assigned into a static stretching group or a control group. The static stretching group was tested with three different rest times (0 min,20 min,40 min) after 2x30s of stretching. Controls were tested before and after a control period (10 min) without stretching. Dorsiflexion range of motion (RoM), passive resistive torque (PRT), and maximum voluntary contraction (MVC) were measured with a dynamometer. Ultrasonography of the medial gastrocnemius (GM) muscle-tendon junction (MTJ) displacement allowed us to determine the length changes in the tendon and muscle, respectively, and hence to calculate their stiffness.Following the stretching, we observed a significant increase in RoM directly following the stretching, 20 min post-stretching, and 40 min post-stretching. However, no changes were found in other functional parameters (PRT, MVC) or structural parameters (muscle and tendon stiffness). No changes were detected in any variable in the control group.We conclude that a static stretching exercise of 2x30s increases the RoM for at least 40 min. However, this gain in RoM is not accompanied with more compliant muscle and/or tendon tissue, suggesting that 60s of static stretching might not be stimulus enough to induce changes in the muscle-tendon structure. Hence, we speculate that other factors, such as increased stretch tolerance, might be responsible for the changes in the RoM observed in the present study

THE INFLUENCE OF SAND SURFACE ON THE KINEMATICS OF VOLLEYBALL SPIKE JUMPS

Several types of sports, like soccer, European handball, and volleyball have expanded their classical fields of activity from indoor surfaces made of wood or synthetic and outdoor turf to sand surfaces. Previous studies reported differences in both body mechanics and energy demands during several types of movement on sand or similar compliant surfaces compared to hard surfaces. Therefore, we investigated the differences in kinematics during spike jumps performed on indoor or sand surface (Tilp et al., 2008)

Experdite : a model based expert diagnostic system using a high level test description language

To be competitive in the development and production of complex electronic systems, a company must constantly scrutinize its manufacturing processes to find ways to reduce costs and increase productivity. One of the more costly problems is the inability to troubleshoot and repair faulty circuit boards on the spot. Rather, they must be divert.ed off the manufacturing line to a senior technician for diagnosis and repair. The purpose of Experdite is to provide a practical expert diagnostic system for manufacturing line personnel so they can quickly troubleshoot and repair most circuit board faults, thereby eliminating the need to send the board off line. Experdite also addresses other inherent manufacturing line issues, including the need to have a general purpose and easily adaptable system to work with many different circuit boards. It addresses the need for an expert diagnostician before anyone has bad the time to become an expert troubleshooter on the circuit board. The final issue addressed is the ability to quickly and easily modify the knowledge base to handle any inevitable hardware changes. The component and self-test behavior for the target circuit board is abstracted and then modeled with a high level Test Description Language, or TDL. A TDL to C++ translator converts the TDL description into a knowledge base of C++ classes. Then the inference engine traces the thread of causality to a fault on a circuit board by gleaning information from the knowledge base and comparing it to the actual behavior of the circuitry. This paper elaborates on each of these points. Also included in the paper are descriptions of the implementation and application of Experdite to a production circuit board

A importância da gestão de custos na bovinocultura de corte do Estado de Rondônia: estudo de caso da Fazenda Brasil Fronteira.

Trabalho de Conclusão de Curso apresentado ao Departamento Acadêmico de Administração da Fundação Universidade Federal de Rondônia, campus Professor Francisco Gonçalves Quiles, para obtenção do título de Bacharel em Administração. Orientador: Prof. M.e Juliano Avelar MouraO atual cenário econômico brasileiro vem passando por uma série de transformações onde o país passa a ser o primeiro no mundo em produção de bens e serviços, neste cenário, a carne bovina toma proporções surpreendentes, onde o país ultrapassou em dez anos duas posições assumindo assim a posição de produtor mundial de carne in natura a frente dos Estados Unidos e Austrália. Rondônia, considerada hoje o “Estado Natural da Pecuária” com um crescimento extraordinário nos últimos dez anos, aproximadamente 120%, coloca-se na ponta de todos estados brasileiros a disputar em breve pela produção nacional de carne bovina. Mas para chegar a este ponto, antes é, necessário que os produtores de bovinos adquiram conhecimento sobre técnicas de gestão, o que hoje não ocorre, pois a maioria das decisões é tomada através do felling, ou seja saber qual o real custo do negócio praticado. Este artigo tratará da importância da gestão de custos na bovinocultura de corte do Estado de Rondônia, refere-se à cria, recria e engorda de bovinos no Município de Pimenteiras D’ Oeste, visitada pelo presente autor do artigo com finalidade de explorar os dados relevantes á gestão de custos. O processo de tomada de decisão no agronegócio através do conhecimento dos reais custos incorridos no processo de engorda de bovinospode gerar resultados esperados com a possibilidade da formação de estratégias de crescimento com um desenvolvimento econômico.

The Corrosion Behavior of Electroless Ni-P-SiC and Ni-Sn-P-SiC Nano-Composite Coating

Abstract: Electroless nickel (EN) and EN composite with SiC and Sn-SiC were deposited by chemical deposition. The microstructure analysis was conducted with scanning electron microscopy, Thin film indicated that the presence of SiC particles did not affect the microstructure of the Ni-P alloy matrix when annealing temperature was below 400°C. EDAX (Energy dispersive x-ray analysis) technique have been applied in order to investigate the chemical composition and indicated that linear relation between SiC concentrations and SiC content. Microhardness of electroless Ni-Sn-P deposite, Ni-P-SiC composite and Ni-Sn-P-SiC composite were studied. Microhardness reached to the maximum value after heating to 400ºC for 1h. Microhardness follow the sequence Ni-P-SiC &gt; Ni-Sn-P-SiC &gt; Ni-P &gt; Ni-Sn-P. Finally, the corrosion resistance of different SiC content and constant concentration of SnCl2 was studied in different corrosive solutions (1M H2SO4 and 3.5% NaCl solution)

Long jump training emphasizing plyometric exercises is more effective than traditional long jump training: A randomized controlled trial

The aim of the study was to evaluate the impact of an 8-weeksplyometric training program on the sprint and jump performance. The intervention study employed a controlled experimental design with two parallel groups of male long jumpers. While the experimental group (n = 18) trained with plyometric exercises, the control group (n=10) performed classical long jump training. Both groups were examined for athletic performance (30m sprint, standing long jump, vertical jump) and biomechanical parameters of a long-jump movement (max vertical height, horizontal and vertical velocity at take-off, flight time, take-off duration) prior and following the intervention. The experimental group demonstrated significantly better developments than the control group in most of the physical and biomechanical parameters respectively and improved their long jump records. Combining an 8-weeksplyometricprogram with athletics training significantly develops long jump and general athletic performance as well as biomechanical parameters. Therefore, plyometric training can be recommended to athletics coaches as an additional training alternative to improve sprint and long jump abilities in athletes

Soleus H-Reflex Inhibition Decreases During 30 s Static Stretching of Plantar Flexors, Showing Two Recovery Steps

During the period when the ankle joint is kept in a dorsiflexed position, the soleus (SOL) H-reflex is inhibited. The nature of this inhibition is not fully understood. One hypothesis is that the decrease in spinal excitability could be attributed to post-activation depression of muscle spindle afferents due to their higher firing rate during the stretch-and-hold procedure. As the static stretching position is maintained though, a partial restoration of the neurotransmitter is expected and should mirror a decrease in H-reflex inhibition. In the present study, we explored the time course of spinal excitability during a period of stretching. SOL H-reflex was elicited during a passive dorsiflexion movement, at 3, 6, 9, 12, 18, 21, and 25 s during maximal ankle dorsiflexion, during plantar flexion (PF) and after stretching, in 12 healthy young individuals. Measurements during passive dorsiflexion, PF and after stretching were all performed with the ankle at 100° angle; measurements during static stretching were performed at individual maximal dorsiflexion. H-reflex was strongly inhibited during the dorsiflexion movement and at maximal dorsiflexion (p &lt; 0.0001) but recovered during PF and after stretching. During stretching H-reflex showed a recovery pattern (r = 0.836, P = 0.019) with two distinct recovery steps at 6 and 21 s into stretching. It is hypothesized that the H-reflex inhibition observed until 18 s into stretching is the result of post-activation depression of Ia afferent caused by the passive dorsiflexion movement needed to move the ankle into testing position. From 21 s into stretching, the lower inhibition could be caused by a weaker post-activation depression, inhibition from secondary afferents or post-synaptic inhibitions

Evolutionary biology and anthropology suggest biome reconstitution as a necessary approach toward dealing with immune disorders

Industrialized society currently faces a wide range of non-infectious, immune-related pandemics. These pandemics include a variety of autoimmune, inflammatory and allergic diseases that are often associated with common environmental triggers and with genetic predisposition, but that do not occur in developing societies. In this review, we briefly present the idea that these pandemics are due to a limited number of evolutionary mismatches, the most damaging being ‘biome depletion’. This particular mismatch involves the loss of species from the ecosystem of the human body, the human biome, many of which have traditionally been classified as parasites, although some may actually be commensal or even mutualistic. This view, evolved from the ‘hygiene hypothesis’, encompasses a broad ecological and evolutionary perspective that considers host-symbiont relations as plastic, changing through ecological space and evolutionary time. Fortunately, this perspective provides a blueprint, termed 'biome reconstitution', for disease treatment and especially for disease prevention. Biome reconstitution includes the controlled and population-wide reintroduction (i.e. domestication) of selected species that have been all but eradicated from the human biome in industrialized society and holds great promise for the elimination of pandemics of allergic, inflammatory and autoimmune diseases