Load absorption force-time characteristics following the second pull of weightlifting derivatives

The purpose of this study was to compare the load absorption force-time characteristics of weightlifting catching and pulling derivatives. Twelve resistance-trained men performed repetitions of the hang power clean (HPC), jump shrug (JS), and hang high pull (HHP) on a force platform with 30, 45, 65, and 80% of their one repetition maximum (1RM) HPC. Load absorption phase duration, mean force, and work were calculated from the force-time data. The HHP produced a significantly longer load absorption phase duration compared to the HPC (p < 0.001, d = 3.77) and JS (p < 0.001, d = 5.48), while no difference existed between the HPC and JS (p = 0.573, d = 0.51). The JS produced significantly greater load absorption mean forces compared to the HPC (p < 0.001, d = 2.85) and HHP (p < 0.001, d = 3.75), while no difference existed between the HPC and HHP (p = 0.253, d = 0.37). Significantly more load absorption work was performed during the JS compared to the HPC (p < 0.001, d = 5.03) and HHP (p < 0.001, d = 1.69), while HHP load absorption work was also significantly greater compared to the HPC (p < 0.001, d = 4.81). The weightlifting pulling derivatives examined in the current study (JS and HHP) produced greater load absorption demands following the second pull compared to the weightlifting catching derivative (HPC). The JS and HHP may be used as effective training stimuli for load absorption during impact tasks such as jumping

Correlational analysis between joint-level kinetics of countermovement jumps and weightlifting derivatives

The purpose of this study was to investigate the mechanical similarity between net joint moments (NJM) of the countermovement jump (CMJ) and the hang power clean (HPC) and jump shrug (JS). Twelve male Lacrosse players performed three maximal effort CMJs and three repetitions of the HPC and JS at 30%, 50%, and 70% of their HPC one repetition maximum (1-RM). Ground reaction forces and motion capture data were used to calculate the NJM of the hip, knee, and ankle joints during each exercise. Statistical comparison of the peak NJM indicated that NJM during the HPC and JS across all loads were equal to or greater than the NJM during the CMJ (all p < 0.025). In addition, correlation analyses indicated that CMJ hip NJM were associated (all p < 0.025) with HPC hip NJM at 30% and 70% (r = 0.611-0.822) and JS hip NJM at 50% and 70% (r = 0.674-0.739), whereas CMJ knee NJM were associated with HPC knee NJM at 70% (r = 0.638) and JS knee NJM at 50% and 70% (r = 0.664-0.732). Further, CMJ ankle NJM were associated with HPC ankle NJM at 30% and 50% (r = 0.615-0.697) and JS ankle NJM at 30%, 50%, and 70% (r = 0.735-0.824). Lastly, knee and ankle NJM during the JS were greater than during the HPC at 30% and 50% of 1-RM (all p < 0.017). The degree of mechanical similarity between the CMJ and the HPC and JS is dependent on the respective load and joint. [Abstract copyright: © Journal of Sports Science and Medicine.

Solution technology of part "hřídel" with CNC machines of unit Fanuc.

Tématem práce je řešení technologie součásti „hřídel“. Charakterizuje sériovou výrobu a technologičnost součásti, zabývá se výběrem vhodných strojů pro obrábění a specifikuje nástroje pro obrábění. Následující část navrhuje technologii výroby a sestavuje program pro CNC soustruh s osou Y. Vyhodnocuje technologii v podmínkách firmy ANTREG, a. s.Topic of this work is a solution of technology of „spindle“ component. It characterizes serial production and technology of the component, it deals with the selection of suitable machine tools and specifies cutting tools. The following part suggests a technology of production and completes a programme for CNC lathe with axis Y. It evaluates the technology in conditions of ANTREG, a. s.

A comparison of catch phase force-time characteristics during clean derivatives from the knee

The aim of this study was to compare load-absorption force-time characteristics of the clean from the knee (CK), power clean from the knee (PCK) and clean pull from the knee (CPK). Ten collegiate athletes (age 27.5 ± 4.2 years; height 180.4 ± 6.7 cm; mass 84.4 ± 7.8 kg), performed three repetitions each of the CK, PCK and CPK with 90% of their 1RM power clean on a force platform. The CK load-absorption duration (0.95 ± 0.35 s) was significantly longer compared to the CPK (0.44 ± 0.15 s; p 0.05, d = 1.08), with no differences between PCK and CPK (p > 0.05, d = 0.91). The CPK demonstrated the greatest mean force (2039 ± 394 N), which was significantly greater than the PCK (1771 ± 325 N; p = 0.012, d = 0.83), but not significantly different to the CK (1830 ± 331 N; p > 0.05, d = 0.60); CK and PCK were not different (p > 0.05, d = 0.18). Significantly more load-absorption work was performed during the CK (655 ± 276 J) compared to the PCK (288 ± 109 J; d = 1.75, p 0.05). Additionally, more load-absorption work was performed during the CPK compared to the PCK (d = 1.90, p = 0.032). Inclusion of the catch phase during the CK does not provide any additional stimulus in terms of mean force or work during the load-absorption phase compared to the CPK, while the CPK may be beneficial in training rapid force absorption due to high force and a short duration

Influence of reactive strength index modified on force- and power-time curves

Purpose: The reactive strength index modified (RSImod) has been recently identified and validated as a method of monitoring countermovement jump (CMJ) performance. The kinetic and kinematic mechanisms that optimize a higher RSImod score are, however, currently unknown. The purpose of this study, therefore, was to compare entire CMJ force-, power-, velocity- and displacement-time curves (termed temporal phase analysis) of athletes who achieve high versus low RSImod scores. Methods: Fifty-three professional male rugby league players performed three maximal effort CMJs on a force platform and variables of interest were calculated via forward dynamics. RSImod values of the top (high RSImod group) and bottom (low RSImod group) twenty athletes’ kinetic and kinematic-time curves were compared. Results: The high RSImod group (0.53±0.05 vs. 0.36±0.03) jumped higher (37.7±3.9 vs. 31.8±3.2 cm) with a shorter time to take-off (TTT) (0.707±0.043 vs. 0.881±0.122 s). This was achieved by a more rapid unweighting phase followed by greater eccentric and concentric force, velocity and power for large portions (including peak values) of the jump, but a similar countermovement displacement. The attainment of a high RSImod score therefore required a taller, but thinner, active impulse. Conclusion: Athletes who perform the CMJ with a high RSImod, as achieved by high jumps with a short TTT, demonstrate superior force, power, velocity and impulse during both the eccentric and concentric phases of the jump. Practitioners who include the RSImod calculation within their testing batteries may assume that greater RSImod values are attributed to an increase in these underpinning kinetic and kinematic parameters

The effect of training with weightlifting catching or pulling derivatives on squat jump and countermovement jump force–time adaptations

The purpose of this study was to examine the changes in squat jump (SJ) and countermovement jump (CMJ) force−time curve characteristics following 10 weeks of training with either load-matched weightlifting catching (CATCH) or pulling derivatives (PULL) or pulling derivatives that included force- and velocity-specific loading (OL). Twenty-five resistance-trained men were randomly assigned to the CATCH, PULL, or OL groups. Participants completed a 10 week, group-specific training program. SJ and CMJ height, propulsion mean force, and propulsion time were compared at baseline and after 3, 7, and 10 weeks. In addition, time-normalized SJ and CMJ force−time curves were compared between baseline and after 10 weeks. No between-group differences were present for any of the examined variables, and only trivial to small changes existed within each group. The greatest improvements in SJ and CMJ height were produced by the OL and PULL groups, respectively, while only trivial changes were present for the CATCH group. These changes were underpinned by greater propulsion forces and reduced propulsion times. The OL group displayed significantly greater relative force during the SJ and CMJ compared to the PULL and CATCH groups, respectively. Training with weightlifting pulling derivatives may produce greater vertical jump adaptations compared to training with catching derivatives

Heterogeneous Queries for Synoptic and Phrasal Search

This paper describes our approaches for the Plagiarism Detection – Source Retrieval task of PAN 2014. We combined and improved methodology used at PAN 2012 and PAN 2013. Our system combines three types of queries: The keywords-based queries; the paragraph-based queries; and the headers-based queries. The queries are distinguished also by other properties such as the phrase query or the positional query. The queries are submitted to two search engines – Chatnoir and Indri – according to their properties. The query’s position serves for the search control, minimization of the total number of executed queries is the system’s priority. Downloaded documents are textually compared with the suspicious document and if a similarity is found, the downloaded document is reported

Approaches for Candidate Document Retrieval

Plagiarism has become a serious problem mainly because of the electronically available documents. An online document retrieval is weighty part of a modern anti-plagiarism tool. This paper describes an architecture and concepts of a real-world document retrieval system, which is a part of a general anti-plagiarism software. A similar system was developed as a part of nationwide plagiarism solution at Masaryk University. The design can be adapted into many situations. Provided recommendation stem from experience of the system operation for several years. The proper usage of such systems contributes to gradual improvement of the quality of student theses

Production of Pattern Equipment for Casting Pump

Tato bakalářská práce se zaměřuje na návrh slévárenské technologie, návrh a výrobu modelového zařízení pro odlitek čerpadla z šedé litiny ČSN 42 2420. V praktické části je zpracován návrh technologie a modelového zařízení pomocí CAD systému SolidWorks. Provedla se simulace lití a chladnutí v CAE systému ProCAST. Pro návrh obráběcí technologie byl použit CAM systém HSMWorks. Na CNC obráběcích strojích se obrobil model, jaderník a podložka. Výsledkem mojí práce je modelové zařízení pro výrobu formy a jádra pro daný odlitek. Na závěr se vyrobili formy, jádra a provedlo se odlití pěti vzorků.The bachelor thesis focuses on the design of foudry technology, design and production of pattern equipment for castiong of pump from cast iron ČSN 42 2420. The practical part elaborates design of technology and pattern equipment in CAD system SolidWorks. Simulation of casting was made in CAE system ProCAST. For design of milling technology was used CAM system HSMWorks. On the CNC machines was machined model, core box and underlay. Result of my thesis is pattern equipment for moulds and cores for the casting. In the end was made molds, cores and five samples of casting was casted.

Spin-induced symmetry breaking in orbitally ordered NiCr_2O_4 and CuCr_2O_4

At room temperature, the normal oxide spinels NiCr_2O_4 and CuCr_2O_4 are tetragonally distorted and crystallize in the I4_1/amd space group due to cooperative Jahn-Teller ordering driven by the orbital degeneracy of tetrahedral Ni$^{2+}$ ($t_2^4$) and Cu$^{2+}$ ($t_2^5$). Upon cooling, these compounds undergo magnetic ordering transitions; interactions being somewhat frustrated for NiCr_2O_4 but not for CuCr_2O_4. We employ variable-temperature high-resolution synchrotron X-ray powder diffraction to establish that at the magnetic ordering temperatures there are further structural changes, which result in both compounds distorting to an orthorhombic structure consistent with the Fddd space group. NiCr_2O_4 exhibits additional distortion, likely within the same space group, at a yet-lower transition temperature of $T$ = 30 K. The tetragonal to orthorhombic structural transition in these compounds appears to primarily involve changes in NiO_4 and CuO_4 tetrahedra