The aim of this study was to investigate the effect of heating and cooling on time course of voluntary and electrically induced muscle force variation. Material and Methods. Ten volunteers performed 50 maximal voluntary and electrically induced contractions of the knee extensors at an angle of 120 degrees under the control conditions and after passive lower body heating and cooling in the control, heating, and cooling experiments. Peak torque, torque variation, and half-relaxation time were assessed during the exercise. Results. Passive lower body heating increased muscle and core temperatures, while cooling lowered muscle temperature, but did not affect core temperature. We observed significantly lower muscle fatigue during voluntary contraction compared with electrically induced contractions. Body heating (opposite to cooling) increased involuntarily induced muscle force, but caused greater electrically induced muscle fatigue. In the middle of the exercise, the coefficient of correlation for electrically induced muscle torque decreased significantly as compared with the beginning of the exercise, while during maximal voluntary contractions, this relation for torque remained significant until the end of the exercise. Conclusion. It was shown that time course of voluntary contraction was more stable than in electrically induced contractions.

Objective. The aim of the present study was to establish the changes in psychosocial adjustment of adolescent girls in the modified lessons of physical education. Material and Methods. An experimental design was used in the study. The experimental group included 14- to 15-year-old adolescent girls (n=128), and the control group comprised adolescent girls of the same school and the same age (n=137). The girls of the experimental group participated in modified physical education lessons. Once a month, they had a theory class where they received knowledge on communication disorders among adolescents and ways of preventing them by means of physical activities. In practical classes, the girls of the experimental group had sports games (basketball, volleyball, and football), enhancing physical abilities, and Pilates exercises. For the estimation of the level of adolescents’ psychosocial adjustment and its components (self-esteem and domination), an adapted questionnaire developed by Rogers and Dymond was applied. An adapted questionnaire developed by Huebner was administered to measure students’ satisfaction with life. Results. The analysis of the data demonstrated that when comparing the psychosocial adjustment of the adolescent girls in the experimental group before and after the experiment, a significant differences in the score of the psychosocial adjustment scale was established (53.81±8.34 vs. 59.41±7.66, P<0.05). After the experiment, high life satisfaction was reported by 42.19% of the girls (P<0.05). Conclusions. After the educational experiment, the index of the psychosocial adjustment scale in the experimental group improved statistically significantly.

The aim of the present study was to establish the influence of muscle heating and cooling on knee flexors and extensors during fatiguing exercise. The participants of the study were 10 healthy males aged 19–23 years. The participants of the study were tested with the isokinetic dynamometer. Control measurements were done before the load as well as 10 min, 30 min, 60 min, and 24 h after the load. The participants performed concentric exercise bouts: 50 knee extensions and flexions at the fixed speed of 180°/s, when femoral muscles before concentric load were of normal temperature, were heated or cooled. Creatine kinase activity in blood serum was estimated 1 h before the load and 24 h after it. Internal temperature of the muscle quadriceps femoris after muscle heating for 45 min increased to 39.5±0.2°C (P<0.001) and after muscle cooling for 30 min decreased to 32.5±0.3°C (P<0.05) as compared to baseline temperature (before heating – 36.9±0.1°C, before cooling – 36.8±0.2°C). Creatine kinase activity in blood serum 24 h after concentric load was significantly increased as compared to control values. Passive muscle warming increased muscle contraction force of knee extensors, but did not cause any changes either in the rate of muscle fatigue or in the rate of muscle recovery. Muscle cooling did not decrease muscle contraction force and did not increase muscle fatigue resistance. The findings of this study showed that both, muscle warming and muscle cooling, brought about a decrease in an indirect parameter of muscle damage – the amount of creatine kinase 24 h after concentric load.

Research background and hypothesis. The severity of recurrence of injuries in track and field athletics gives possibility to adjust training programs for athletes.  Research aim was to analyse which body parts are mostly injured and the severity of recurrence of injuries in track and field athletics gives possibility to adjust training programs for athletes.Research methods. Thirty six athletes were given questionnaires developed using standardized methodology validated by the IOC and implemented by the IAAF during international track and field competitions.Research results. There were 64 cases of injuries among 33 athletes: head and trunk cases – 12 (18.8%), upper extremity – 14 (21.9%), lower extremity – 38 (59.4%). In all cases lower extremity injuries dominated. In sprinters lower extremity injuries dominated and there was no upper extremity trauma. In throwers the upper and the lower extremity were equally vulnerable, mild and very mild injuries were observed. There was no difference between both groups in recurrence of the same trauma.Discussion and conclusions.  Estimating which body parts are mostly injured in sports gives the possibility to  adjust  training  programs  for  athletes,  increasing  the  amount  of  athletic  exercises  intended  for  the  functional preparation of those parts.  Injuries in track and field are frequent and dominating injuries are of lower extremity; there exist the possibility of recurrence of the injury in the same body part. Injuries prevalent in sprinter cohort are of lower extremities, and injuries prevalent in throwing cohort are of lower and upper extremities.

ĮvadasPažangios ekonomikos šalyse daugiausia žmonių miršta nuo širdies ir kraujagyslių sistemą pažeidžian-čių ligų bei sindromų. Šios ligos sudaro apie pusę visų mirties ir vieną trečdalį invalidumo priežasčių. Svarbiausi jų yra aterosklerozės, ypač vainikinių širdies arterijų, sukelti miokardo išemijos sindromai, kurie dėl didelio paplitimo ir blogos baigties (invalidumas, miokardo infarktas ir staigi mirtis) dabar sudaro vieną svarbiausių medicininių ir socialinių problemų. Todėl šie sindromai dažnai apibūdinami vienu nozologiniu vienetu -vadinamąja išemine širdies liga (IŠL). PSO vykdomi platūs tarptautiniai IŠL patogenezės, klinikos, diagnostikos, gydymo bei profilaktikos tyrimai (1, 2). Sergamumas miokardo infarktu ir mirtingumas nuo IŠL yra susijęs su rizikos veiksniais. Daugelio šalių patirtis rodo, kad laiku pradėta rizikos veiksnių korekcija padeda sumažinti sergamumą MI (3-6). Vienas svarbiausių veiksnių, nulemiančių širdies fiziologiją ir patologiją, yra vainikinė kraujotaka. Vainikinių širdies kraujagyslių būklei įtaką daro jų inervacija, kuri užtikrina kraujagyslių sienelės tonuso refleksinę reguliaciją. Dabar mokslininkai skiria daug dėmesio prieširdžių miokardo autonominių nervinių rezginių tyrimams, nes prieširdžiuose yra svarbiausios širdies ritmo dažnio valdymo bei elektrinio signalo perdavimo struktūros. Daugeliu neuroanatominių tyrimų nustatyta, kad prieširdžių miokarde yra žymiai tankesni nei