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  • Author: Paulina Szyszka x
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The Relationship Between Biomechanical Indicators of the Snatch Technique and Female Weightlifters' Levels

Abstract

Introduction. The snatch technique is a discipline in Olympic weightlifting. The lifter has to raise the barbell from the platform directly above their head in one movement. While reviewing the literature on biomechanical analysis of the techniques of weightlifting, one can find positions on the analysis of parameters, such as barbell track, horizontal displacement, and angular positions of the joints in the individual phases of the lifter's movement. Many texts concern female and male lifters taking part in World or European Championships. The parameters of the best competitors are outlined - mostly those who finish in the top five places in competition. Mostly these are parameters regarding male lifters, and less frequently those of female lifters. In the literature review, an overlooked aspect is that of the definition of the diversity of indicators as regards the snatch technique practiced by female lifters depending on score. Material and methods. In the research, registered snatch attempts during the World Championship were used. Videos were used by judges to establish a maximum weight limit for female lifters. The attempts were registered by two cameras and were later digitally processed by the APAS 2000 system. Barbell parameters, maximum speed, average of the bar, and the parameters of the lifter-bar collocation (horizontal displacement of barbell weights and height elevation) were assessed. Results. The analysed attempts show the margin of error for measurement of the average speed of the barbell as 0.03 m/s. The difference in maximum speed of analysed attempts is 15%. The height of clearance of the first-placed female lifter's barbell was 12.7 cm, 30 cm for the last-placed. Conclusions. The sporting level of weightlifting by female lifters influences the analysed biomechanical indicators of the snatch. Those indicators, which are similar in the case of both the World Championship winner and the female lifter who came last, may be described as the average speeds of the barbell. The high sporting level of female lifters performing heavy lifting is characterized by the clearance of the barbell.

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Relationship between Muscle Torque and Performance in Special and Specific Exercises in Young Weightlifters

Abstract

Introduction. The aim of the current study was to examine the relationship between knee and elbow isometric muscle torque values and the results obtained in special and specific exercises in young weightlifters. Material and methods. The study involved eight young weightlifters (age: 19.9 ± 4.3 years; height: 176.8 ± 10.6 cm; weight: 69.0 ± 19.7 kg - pretest, 70.9 ± 21.6 - posttest). Their performance put them in the second and third top classes of weightlifters their age according to the Polish norms for weightlifting (the so-called ‘national class’ and ‘first class’ in the Polish system, which are lower than the ‘international class’). The differences between the values obtained in the first measurement of torque performed at the beginning of the preparation period and those obtained at the beginning of the immediate pre-competition period were compared with the differences in the maximal load lifted in special and specific exercises. Results. The training that the weightlifters underwent during the preparation period caused a significant increase in the relative torque values of the knee extensors (0.56 Nm/kg on average, p ≤ 0.047) and those of the elbow flexors (0.35 Nm/kg, p ≤ 0.0002). Significant differences (p ≤ 0.05) were observed between the results obtained in all of the special and specific exercises examined. A statistically significant relationship was also found between the changes in relative torque values and the results achieved in special and specific exercises. Conclusions. The regression equations derived in the study can help predict sports performance outcomes based on the results of laboratory tests.

Open access
Biomechanical Analysis of Successful and Unsuccessful Snatch Lifts in Elite Female Weightlifters

Abstract

The aim of this study was to identify biomechanical factors affecting successful and unsuccessful snatch attempts in elite female weightlifters during the 2013 World Weightlifting Championships. Fourteen female competitors took part in this study. Their successful and unsuccessful snatch lifts with the same load were recorded with 2 camcorders (50 Hz), and selected points were digitized manually on to the body and the barbell using the Ariel Performance Analysis System. The kinetic and kinematic barbell movement as well as the athlete’s body movement variables during the liftoff phase were examined. The results of this study show statistical differences (p ≤ 0.05) between successful and unsuccessful attempts in relation to the angle values in the knee and hip joints in preparation for the aerial phase position. Similarly, the center of gravity velocity was significantly higher in successful attempts during the catch phase. Thus, coaches should pay particular attention to the accuracy of the execution in preparation for the aerial phase position and to the velocity of the center of gravity of the competitors during the catch phase.

Open access
Biomechanical Assessment of Strength and Jumping Ability in Male Volleyball Players During the Annual Training Macrocycle

Abstract

Introduction. The aim of the study was to determine the changes in the peak torque of the knee extensors and flexors of the dominant lower limb, the shoulder internal and external rotators of the dominant upper limb, and the shoulder extensors and flexors of the dominant upper limb as well as the changes in jump height in volleyball players during the annual training macrocycle.

Material and methods. The study involved 13 volleyball players from a Polish second-league team. The measurements were performed five times: before the preparation period (T1), at the beginning of the competitive season (T2), in the middle (T3) and at the end of the first competition period (T4), and after the competitive season (T5). The torque of the knee muscles and shoulder rotators was measured in isokinetic conditions, and the torque of the shoulder extensors and flexors was assessed in isometric conditions. Jumping ability was tested using a piezoelectric platform.

Results. We observed statistically significant differences (p < 0.05) in jump height and relative peak torque between the measurements, except for the torque of the shoulder external rotators and flexors. The results of multiple factor analysis based on 5 sets composed of 5 strength variables revealed differences between subjects and measurement sessions.

Conclusions. The results obtained indicate that strength and jumping ability should be assessed regularly during the competitive season. The findings of the study suggest that it is necessary to modify the training methods used during the preparation period and individualize the training in the final phase of the competition period.

Open access
Biomechanical Assessment of Motor Abilities in Male Handball Players During the Annual Training Macrocycle

Abstract

Introduction. The aim of the study was to determine the torque of the knee extensors and flexors of the lead lower limb, the torque of the shoulder extensors and flexors of the dominant upper limb, and the torque generated by the muscles of the kinematic chain going from the trail lower limb to the hand of the dominant limb in male handball players during the annual training macrocycle. Changes in jump height and throwing velocity were also investigated. Material and methods. The study involved 13 handball players from a Polish second-league team. The measurements were performed four times: at the beginning of the preparation period, at the beginning of the season, at the end of the first part of the season, and at the end of the second part of the season. Torque was measured in isokinetic and isometric conditions. Jumping ability was tested using a piezoelectric platform, and throwing velocity was measured with a speed radar gun. Results. The study found statistically significant differences between the relative torque values of the knee extensors (p < 0.002) and flexors (p < 0.003) of the lead leg measured in isokinetic conditions between the first three measurements and the final one. Isokinetic measurement of the torque of the muscles of the kinematic chain going from the trail leg to the hand of the dominant arm decreased in a statistically significant way at the end of the season. As for the results of the measurement of the torque of the shoulder extensors and flexors in static conditions, no statistically significant differences were observed between the four measurements. However, statistically significant differences were noted in jumping ability and throwing velocity in the annual training macrocycle. Conclusions. The results of the study indicate that there is a need to perform regular assessments of players’ strength and jumping ability during the competition period. There is a need to modify the training methods used during the preparation period and in the second part of the season as well as to individualise training at the end of the competition period.

Open access
Nampt (Visfatin) Influence on Proliferative Activity of Normal Rat Adrenocortical Cells and Human Adrenal Corticocarcinoma Nci-H295r Cells

Abstract

Nampt (Nicotinamidephosphoribosyltransferase - also known as visfatin/PBEF) is the enzyme that regulates the NAD+ level, therefore influencing many metabolic pathways within the cells. As circulating cytokine, extracellular Nampt (eNampt) exerts pro-inflammatory, pro-chemotactic, pro-angiogenic and insulin-like effects; however the mechanism of eNampt action is still unclear.Earlier studies have shown that eNampt exerts a stimulating effect on the proliferation of many cancer cell lines. However, the effect of this cytokine on cell proliferation in primary culture is little known. Therefore, the aim of the study was to analyse the influence of eNampt on the proliferation of rat adrenocortical cells in primary culture and to investigate similar influence of eNampt on the line H295R of human adrenal corticocarcinoma cells. Proliferation of the examined cells was assessed using the RTCA (Real Time Cell Analyzer) method. The obtained results indicate that eNampt stimulates the proliferation of H295R cells, but does not change the proliferation of cultured rat adrenocortical cells. In primary culture of rat adrenocortical cells, Fk866 (specific Nampt inhibitor) does not modify the rate of proliferation of tested cells. In H295R cells the addition of Fk866 alone inhibits proliferative activity and stimulates apoptosis. Fk866 also inhibits the stimulating effect of eNampt on H295R cell proliferation.

Open access