Effect of Additional Load on Power Output during Drop Jump Training
Plyometrics can be an effective way of improving power performance in many sports. The purpose of this study was to examine the effects of additional loading on power during drop jump training. Forty-two untrained physical education students with plyometric training background participated in a six-week training 3 times a week. Subjects were randomized to one of three training groups: without (FREE) and with a weight vest (VEST; 5% body weight), and a control group (CON). Pretraining and post-training measures of concentric peak power (PP), force (Fpp) and velocity (υPP) at peak power and, in addition, time between eccentric and concentric peak power (tPPEC) were analyzed in a countermovement jump (CMJ) and a drop jump (DJ) from a height of 0.3 m. The FREE and VEST groups considerably improved PP in CMJ (p < 0.05), but υPP significantly increased (p < 0.05) and tPPEC significantly decreased (p < 0.05) only in the FREE group. The enhancement of PP and υPP was only demonstrated by the FREE group in DJ. The FREE group significantly decreased (p < 0.05) and the VEST group significantly increased (p < 0.05) tPPEC in DJ. It can be concluded that using additional load during drop jump training does not produce superior gains in power output when compared to a traditional drop jump training program.
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.
Application of fly ash agglomerates in the sorption of arsenic
The scope of this contribution was to investigate in detail an application of fly ash adsorbent for the removal of arsenite ions from à dilute solution. The experiments have been carried out using fly ash from black coal burning power plant "Siersza" and brown coal burning power plant "Turów" (Poland), which was wetted, then mixed and tumbled in the granulator with a small amount of cement to increase the mechanical strength of agglomerates. The measurements of arsenic adsorption from the aqueous solution were carried out in the flask (with shaking), as well as in the column (with circulation), in order to compare two different methods of contacting waste with adsorbent. The adsorption isotherms of arsenic were determined for granulated material, using the Freundlich model. Kinetics studies indicated that the sorption follows a pseudo-first-order (PFO) model (Lagergren) and the Elovich-type model.
The aim of this paper was to analyze reasons and a range of changes in agricultural land areas due to allocation them for non-agricultural purposes across a period of 1990-2015 in Poland. This phenomena has not been sufficiently considered till now. Lack of this knowledge does not allow effective reduction of the decline of agricultural land by appropriate legislation and administrative action, especially on urban areas. In Poland, a significant proportion of agricultural land is allocated annually for non-agricultural purposes, which is connected with their permanent withdrawal from agricultural production. The permanent decline in the area of agricultural land in the country has been observed since the beginning of the systemic transformation. The dominant direction of the land withdrawal for non-agricultural purposes is their allocation to housing construction. In 1995 the Law on the protection of agricultural and forest land was introduced. This law includes strengthened economic tools for the protection of agricultural land in the form of mandatory charges for the withdrawal of agricultural land showing the best soil quality. This has led to a significant reduction in agricultural land use withdrawal. However, accelerated regional development following the accession of Poland to the EU and, then, the need to expand technical infrastructure resulted in several amendments to the 1995 Act, significantly weakened the protection of agricultural and forest land. It seems that the land as the unrepeatable good should be strictly covered by more respect and protection than ever before, especially in areas with the highest production value.