The objective of the study was to examine long summer vacation (LSV) effect on physical activity (PA) in 68 children from three Slovenian cities. PA was assessed over five consecutive days using accelerometer in 6- to 8-year-old children (N = 68; 35 girls and 33 boys, mean age 7.0 ± 0.8 years). PA was assessed on two occasions, before and after LSV and showed clear Gaussian distribution model. PA dropped after LSV for boys (9.6%, P = 0.004) and girls (9%, P = 0.014). Furthermore, PA intensity changed significantly after LSV. In boys inactivity increased after LSV from 69% to 72.2% (P = 0.009) and in girls from 71.7% to 74.2% (P = 0.031), while light PA decreased from 26.9% to 24% (P = 0.005) in boys and from 24.6% to 22.5% (P = 0.035) in girls. In 27% of boys and in just 13% of girls the amount of physical activity in June also determined the amount of physical activity in September. Furthermore, we found a significant drop in physical activity only in boys (P = 0.002) and girls (P < 0.001) with higher initial (June 2007) values. In conclusion we could state that there is a clear negative effect of long summer vacation on physical activity habits and needs further investigations for clear explanation. 

The chronic effects of physical activity on cognitive functions are scarcely documented. The aim of this experiment was to give inligth on the influence of single bouts of exercise at different intensities on the amplitude and latency of P300 component of cognitive potentials in the offense team of American football players. The subject sample consisted of 11 male athletes – members of the American football team “Dukes” Novi Sad, all engaged in the offense team. The control group was formed of 10 age matched students of the University of Novi Sad who were not engaged in any organized physical activity. In the present study the participants were engaged in single bouts of exercise on a cycle ergometer at different intensities. In American football players the amplitude of P300 wave after exercise intensity achieved at 75% HRmax (Fz 15.34±3.99 mV; Cz 19.00±6.26 mV) was statistically higher (p<0.05) than the amlitude at rest (Fz 11.08±4.65 mV; Cz 13.00±5.16 mV) and after exercise at 60% HRmax (Fz 11.87±4.39 mV; Cz 13.43±3.13 mV). There was a significant decrease in amplitude after exercise at 90% HRmax (Fz 11.96±4.48 mV; Cz 13.82±7.10 mV) to the levels of baseline values obtained at rest. In the control group the amplitude of P300 wave after exercise intensity achieved at 60% (Fz 11.02±4.99 mV; Cz 13.98±2.31 mV) and 75% HRmax (Fz 11.58±3.97 mV; Cz 14.64±1.94 mV) were statisticaly higher (p<0.05) than the amplitude of P300 at rest (Fz 7.99±2.95 mV; Cz 11.56±1.81 mV) and after 90% of maximal puls (Fz 8.76±3.05 mV; Cz 12.63±3.31 mV). There were no differences (p>0.05) between the amplitudes after 60% and 75% of HRmax, as well as between the values obtained at rest and after 90% of HRmax. Short duration exercise corresponding to 75% HRmax facilitated cognitive processing in the CNS in athletes, showing that strenuous exertion on the field improves cognitive capabilities in American football players. 

The aim of the study was to examine the effects of head-down bed rest on psychological well-being in young healthy subjects. Head-down tilting bed rest (BR) is a well-accepted method by which to simulate an acute stage of human adaptation to the microgravity in space flights and also an important model to study consequences of physical inactivity and sedentarism on human body. The subject participating in the study were ten healthy males aged between 20 and 30 who were exposed to a 35-day strict rest in hospital environment. The participants were asked to complete psychometrical inventories – General Health Questionnaire, Satisfaction with Life Scale, State Anxiety Inventory, Center for Epidemiological Studies Depression Scale and Emotional States Questionnaire – on before and after the BR experiment. There were no significant differences in examined psychological variables between pre and post BR period. Research results do not show any adverse effects of a prolonged physical inactivity on perception of health and psychological well-being of selected group of subjects. The importance of this research was to provide evidence that the provision of favourable habitability countermeasures can prevent deterioration in the psychological state under conditions of physical immobilisation. Our findings applied value in the field of health prevention and rehabilitaion. Research of psychological and cognitive aspects within bed rest studies deserves special attention and consideration in the future. Psychic balance and emotional strength have undoubtedly an important role in reducing the consequences of physical impairment and physiological changes due to prolonged bed rest.