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Introduction. The purpose of practicing sport is to improve one’s physical fitness and technical skills. Highly specialized training strengthens particular muscles, which due to repeated overuse may become hypertonic and shortened. This kind of disorder of soft tissues surrounding joints limits the articular range of motion and causes pain, which in effect reduces an athlete’s ability to compete. Aim of Study. The aim of this study was to evaluate the state of muscle balance in field hockey players. The research sample consisted of seventeen professional players from the Polish National Field Hockey Team from 2009. Material and Methods. The research methods included muscle length tests and a questionnaire survey on players’ pain symptoms and their knowledge about maintaining muscle balance. Results. Insignificant asymmetric muscle balance disorders were found in the upper limb region. The external rotators of the shoulder joint were the most overused muscles. Significant symmetric muscle length disorders were found in the lower limb region – the iliopsoas was shortened in 100% of cases, and rectus femoris in 63%. Conclusions. Several conclusions were drawn. The most significant one is that all field hockey players exhibit disturbances in muscle length and suffer pain. This research shows which muscles are highly overloaded and should be taken into consideration in developing programs of stretching exercises. To improve the efficiency of these exercises they should be supervised by an experienced physiotherapist.
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Mechanical strength of stems in aquatic macrophytes

72%
In populations of submerged macrophytes, individuals are selected in terms of resistance to the effect of hydrodynamic forces. The aim of this study was to check whether individuals growing in river water are more tensile and bending resistant than plants occurring in places not exposed to flow stress. We determined the ultimate tensile strength of stems in four macrophyte species, Potamogeton natans, P. pectinatus, Batrachium fluitans and Chara fragilis, which occur in two environmental variants: in running (current velocity of 0.1-0.6 m/s-1) and stagnant water. In addition, flexure of P. natans stems from both environmental variants was examined. What is more, the type and arrangement of strengthening structures in stems of the plants under study were determined. Potamogeton natans stems are the most resistant to stretching (15.6±4.7 N), while stems of P. pectinatus (3.3±1.0 N) and Batrachium fluitans (2.6±0.8 N) are less resistant. Chara fragilis (0.6±0.3 N) has the least resistant stems. Batrachium, Chara and P. pectinatus are more resistant to stretching if they occur in a river current, whereas P. natans, in stagnant lake water. Ultimate bending moment of P. natans stems from lakes is also much greater than of stems from a river (9.75•10-3 – 4.25•10-3 Nm as compared to 2.12•10-3 – 1.00•10-3 Nm). The resistance of stems to breaking is directly proportional to the stem and thallus cross sectional areas. On the one hand, in all the studied Cormophyta species, the more resistant stems (in P. natans from stagnant water, in the others from running water) are thicker and characterised by a higher contribution of air spaces in the overall stem cross-section. On the other hand, the stems retain their species specific structure and have a similar proportion of strengthening elements.
The purpose of this study was to examine the influence of sex on the acute effect of static-passive one-session stretching on V sit-and-reach scores in university students. A sample of 76 college students aged 19–30 years were divided into a women group (n = 36) and men group (n = 40). During one session the students performed stretching exercises for the major body muscles using the static-passive technique. Hamstring and lower back muscles extensibility was estimated by the V-sit-and-reach test at the beginning and at the end of the stretching session. The results of the two-way ANOVA with the Bonferroni adjustment showed that females and males did not show a different response to the one-session stretching intervention (p > 0.05). However, both the women and men increased statistically their scores after performing the stretching session (p < 0.001). In conclusion, no differences have been found in the trainability of flexibility by sex. However, there are differences of flexibility by the sex of students, being the females, who obtained the highest marks in the V-sit-and-reach. All this knowledge could help coaches to design more effectives stretching programs.
Swelling pressure in longitudinal direction has been determined on the basis of the time dependence of intensity of hygro-mechanical creep on the stretching, by the method of Moliński and Raczkowski [11]. The external stress needed for total inhibition of unidirectional spruce wood longitudinal swelling has been established. The maximum value of the swelling pressure determined on the basis of hygro-mechanical deformations of spruce wood samples simultaneously subjected to stretching in longitudinal direction and moistening is 14.4 MPa which is by 60% higher than the corresponding value found by the direct method of swelling inhibition for spruce wood sample of the same density.
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