Adriana Cristine Koch Buttelli, Stephanie Santana Pinto, Maira Cristina Wolf Schoenell, Bruna Pereira Almada, Liliana Kologeski Camargo, Matheus de Oliveira Conceição and Luiz Fernando Martins Kruel
The aim of this study was to compare the effects of single vs. multiple sets water-based resistance training on maximal dynamic strength in young men. Twenty-one physically active young men were randomly allocated into 2 groups: a single set group (SS, n=10) and a multiple sets group (MS, n=11). The single set program consisted of only 1 set of 30 s, whereas the multiple sets comprised 3 sets of 30 s (rest interval between sets equaled 1 min 30 s). All the water-based resistance exercises were performed at maximal effort and both groups trained twice a week for 10 weeks. Upper (bilateral elbow flexors and bilateral elbow extensors, peck deck and inverse peck deck) as well as lower-body (bilateral knee flexors and unilateral knee extensors) one-repetition maximal tests (1RM) were used to assess changes in muscle strength. The training-related effects were assessed using repeated measures two-way ANOVA (α=5%). Both SS and MS groups increased the upper and lower-body 1RM, with no differences between groups. Therefore, these data show that the maximal dynamic strength significantly increases in young men after 10 weeks of training in an aquatic environment, although the improvement in the strength levels is independent of the number of sets performed.
The dynamic strength and accumulated plastic strain are two important parameters for evaluating the dynamic response of soil. As a special clay, the remolded red clay is often used as the high speed railway subgrade filling, but studies on its dynamic characteristics are few. For a thorough analysis of the suitability of the remolded red clay as the subgrade filling, a series of long-term cyclic load triaxial test under different load histories are carried out. Considering the influence of compactness, confining pressure, consolidation ratio, vibration frequency and dynamic load to the remolded red clay dynamic property, the tests obtain the development curves of the dynamic strength and accumulated plastic strain under different test conditions. Then, through curve fitting method, two different hyperbolic models respectively for the dynamic strength and accumulated plastic strain are built, which can match the test datum well. By applying the dynamic strength model, the critical dynamic strength of the remolded red clay are gained. Meanwhile, for providing basic datum and reference for relevant projects, all key parameters for the dynamic strength and accumulated plastic strain of the remolded red clay are given in the paper.
Krzysztof Maćkała, łukasz JÓŹwiak and Jacek Stodółka
Introduction. Distance running performance is a simple function of developing high speeds and maintaining this speed as long as possible. Thus a correct running technique becomes an important component of performance. Technique is effective if the competitor can reach a better performance result with the same or lower energy consumption. The purpose of this investigation was to examine a six weeks application explosive type strength training on lower extremities power and maximum speed performance improvement in order to facilitate running technique in sub-elite male middle-distance runner. Material and methods. A sub-elite runner performed twice a week special exercises and running drills. He completed a pre and post-training jumping (SJ, CMJ, standing long jump, standing five jump) and speed (20 m from standing and flying start) field tests. For kinematical analysis, a video (SIMI Motion System) of a 10 m sprint from a 20 m flying start was collected. Results. Improvement occurred in all measurements but strong changes were evident in the 10 m from 20 flying start and in stride frequency from 3.90 to 4.01 Hz, due to decreasing of ground contact time from 160 to 156 ms. No strong evidence in the participant's running technique changes. Conclusion. This proved that six weeks of dynamic type strength program seems to improve neuromuscular characteristics of running speed and explosive power and no changes in running technique.
Sergio Maroto-Izquierdo, David García-López and José A de Paz
Therefore, the aim of this study was to analyse the effects of 6 week FRTEO on maximal dynamicstrength and power output at different submaximal loads, vertical jump height, sprint time, agility and muscle thickness in professional handball players. These effects were compared to those induced by traditional in-season weight training. We hypothesized that FRTEO would lead to a higher increase in all functional, structural and dependent variables that were analysed.
A randomized controlled study was designed to compare the effects of FRTEO with
Performance in all canoe disciplines is based on the physical condition of the paddler and his technique and mental ability to adapt to the racing condition. The strength belongs to the most important physical factors in canoe sprint and canoe slalom disciplines. We believed that in canoe freestyle the strength has an important role in relation to the performance in comparison to other canoe disciplines. The aim of this study was to identify the relationship between upper body strength and special canoe freestyle performance. The study group consisted of 16 senior kayak freestyle paddlers in the age group 26 ± 3 years old. Fitro Dyne Premium was device used to obtain data for analysis of the level of general upper body strength abilities. To determine special upper body strength we used tests on paddle machine and freestyle kayaking flat water tests. Freestyle performance was measured during ECA Euro Cup 2013 competition in Slovakia, Čunovo by official ICF judges. The data obtained were measured by the Spearman Correlation (r) correlation test. The results of the study show significant relations between kayak freestyle performance and test of general strength endurance (p < 0.05), special strength endurance, special dynamic strength (p < 0.01). There were no statistically significant correlations between kayak freestyle performance and general maximal power, dynamic strength, special maximal power.
This study aimed to investigate the acute effects of two strength-training protocols on the neuromuscular and cardiorespiratory responses during endurance exercise. Thirteen young males (23.2 ± 1.6 years old) participated in this study. The hypertrophic strength-training protocol was composed of 6 sets of 8 squats at 75% of maximal dynamic strength. The plyometric strength-training protocol was composed of 6 sets of 8 jumps performed with the body weight as the workload. Endurance exercise was performed on a cycle ergometer at a power corresponding to the second ventilatory threshold until exhaustion. Before and after each protocol, a maximal voluntary contraction was performed, and the rate of force development and electromyographic parameters were assessed. After the hypertrophic strengthtraining and plyometric strength-training protocol, significant decreases were observed in the maximal voluntary contraction and rate of force development, whereas no changes were observed in the electromyographic parameters. Oxygen uptake and a heart rate during endurance exercise were not significantly different among the protocols. However, the time-to-exhaustion was significantly higher during endurance exercise alone than when performed after hypertrophic strength-training or plyometric strength-training (p <0.05). These results suggest that endurance performance may be impaired when preceded by strength-training, with no oxygen uptake or heart rate changes during the exercise.
Research in the field of fracture mechanics and determination of material characteristics are used for practical purposes, such as the assessment of static and dynamic strength of structural components, analysis of their fatigue life or extending the life span of their operation. A structural component, considered to be safe from fatigue cracking point of view, was investigated and results were presented in this article. In particular, an analysis was made to determine the stress intensity factor for the cracked wing flap construction, based on static and fatigue tests, using the Irwin-Kies theory. The flap with a service crack was subjected to fatigue tests with a load similar to the one registered during flight measurements. The flap without a service crack was subjected to static tests, after cutting the cracks of specified lengths and shapes (similar to the service crack) in the skin of the flap. The article presents changing the length of the flap crack in subsequent load cycles, change in the maximum values of force and the crack opening displacement in subsequent load cycles, dependence of P-COD in the first and second stage of fatigue testing of the wing flap, dependence of the wing flap compliance on the length of the crack and experimentally determined dependence for wing flap. The occurrence of a flap crack up to approximately 230 mm does not cause a significant growth of the stress intensity factor.
Failure Criterion for Concrete, Journal of the Engineering Mechanics Division, American Society of Civil Engineering, 103 (EM 4), 527–535, 1977.
8. M. K lisiński , Degradation and plastic deformation of concrete (in Polish), Institute of Fundamental Technological Research Polish Academy of Sciences Report 38, Warsaw, 1984.
9. J. P odgórski , Critical States in Solids with Internal Friction (in Polish), Institute of Fundamental Technological Research Polish Academy of Sciences Report 25, Warsaw, 1986.
10. A. S tolarski , DynamicStrength
Klaus Wirth, Michael Keiner, Hagen Hartmann, Andre Sander and Christoph Mickel
unpleasant to painful.
Maximum dynamicstrength was determined through the load of the one repetition maximum (1RM) in the squat or the leg press 15 min after determining MIF. The maximal load was determined in a series of 1RM. Determination of the 1RM was achieved within a maximum of 5 trials. Rest periods between attempts were at least 5 min. The criterion for a successful attempt in the squat was a trial in which the upper part of the knee musculature was parallel to the floor at the turning point and the leg was completely extended in the upright position. Attempts
Mile Cavar, Marin Corluka, Ivana Cerkez, Zoran Culjak and Damir Sekulic
Rehabil Med , 1998; 30: 131-137
Cavagna Ga, Legramandi MA, La Torre A. Running backwards: Soft landing-hard takeoff, a less efficient rebound. Proc Biol Sci , 2011; 278: 339-346
Chaouachi A, Brughelli M, Chamari K, Levin Gt, Ben Abdelkrim N, Laurencelle L, Castagna C. Lower limb maximal dynamicstrength and agility determinants in elite basketball players. J Strength Cond Res , 2009; 23: 1570-1577
Dayakidis MK, Boudolos K. Ground reaction force data in functional ankle instability during two cutting movements. Clin