ABSTRACT
Collegiate American football injuries for two year seasons in Japanese Kansai Division I team were analyzed using injury rates (IR) per 1000 athlete-exposures (1000AE: one athlete-exposure was defined as a player participating in one game or one practice.), especially focusing on lower limb injuries. The overall game injury rate (GIR: 38.3) was significantly higher than practice injury rate (PIR: 13.1) (X<sup>2</sup>=12.355, p < 0.05). The difference between GIR in 2008 season (50.8) and in 2007 season (25.7) was significant (X<sup>2</sup>=8.235, p < 0.05). The lower extremity injuries approximately occupied 60% of all injuries, especially GIRs of both ankle inversion sprains (3.8) and anterior cruciate ligament (ACL: 3.3) injuries being much higher. PIR in this study was higher than the rates of collegiate American football teams in the U.S.A., especially PIRs of knee ligament injuries (ACL and medial collateral ligament injuries) and ankle sprains (inversion and eversion sprains) being much higher. Regarding the occurrence of injury, GIR with contact in ACL injuries (2.8) and GIR without contact in ankle inversion sprains (2.4) were the highest. It is also necessary to change practice plans and circumstances so that the PIR of knee and ankle injuries could be reduced. Research is needed on injury prevention for knee and ankle injuries in the games and practices.
ABSTRACT
The present study was designed to examine the effects of aerobic exercise on the change of alpha wave component in electroencephalogram (EEG) and plasma β-endorphin. Exercise consisted of 30-min cycling on an ergometer with the load adjusted to elicit a heart rate rise of 50% between resting and predicted maximal value. The EEG signals and blood samples were obtained before and after 30-min exercise. The EEG signal was digitized at a sampling frequency of 64 Hz and analyzed by means of computer-aided decomposition algorithm and frequency power spectral analyses, respectively. The blood samples were immediately centrifuged for 15-min for quantitative analysis of β-endorphin by means of radioimmunoassay method. Results indicated that β-endorphin was significatly (p<.05) greater after exercise as compared to that of the resting contorol. It was also found that the larger the changes in β-endorphin following exercise, the higher the appearance rate of alpha wave in EEG. There was a positive and significant correlation (r=563, p<0.05) between the increase in alpha wave component and that of the plasma β-endorphin. These results suggest that traquilizer effects of aerobic exercise could be explained, at least in part, by the increase of alpha wave component and plasma β-endorphin which in turn bring about the relaxation effects upon the central nervous system.
ABSTRACT
The present study was designed to examine the effects of aerobic exercise on the change of alpha wave component in electroencephalogram (EEG) and plasma β-endorphin. Exercise consisted of 30-min cycling on an ergometer with the load adjusted to elicit a heart rate rise of 50% between resting and predicted maximal value. The EEG signals and blood samples were obtained before and after 30-min exercise. The EEG signal was digitized at a sampling frequency of 64 Hz and analyzed by means of computer-aided decomposition algorithm and frequency power spectral analyses, respectively. The blood samples were immediately centrifuged for 15-min for quantitative analysis of β-endorphin by means of radioimmunoassay method. Results indicated that β-endorphin was significatly (p<.05) greater after exercise as compared to that of the resting contorol. It was also found that the larger the changes in β-endorphin following exercise, the higher the appearance rate of alpha wave in EEG. There was a positive and significant correlation (r=563, p<0.05) between the increase in alpha wave component and that of the plasma β-endorphin. These results suggest that traquilizer effects of aerobic exercise could be explained, at least in part, by the increase of alpha wave component and plasma β-endorphin which in turn bring about the relaxation effects upon the central nervous system.