The influence of intensive Judo training on serum immunoglobulins IgG, IgM, and IgA was studied in 24 Judo fighters. Subjects were assigned to an exercise training group (EXE; n=12) and non-exercise control group (Con; n=12). Subjects in EXE group participated in exercise sessions 4 days a week for 8 wk. Serum samples were collected before, immediately and 1wk after study period. The IgG levels were significantly increased immediately after exercise training (p=0.001) in EXE compared to Con. However, IgM and IgA concentrations showed significant decrease immediately after exercise in EXE (p=0.001). The concentrations of all immunoglobulins had returned to baseline by 1wk of recovery. In conclusion the increased IgG levels are possibly due to isotype switching or a secondary antibody responses that could be considered as enhancement in immune system function. However, chronic suppression of immuniglobulins IgM and IgA may be mediated by hormonal changes associated with exhausting exercise.

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.