[A study on the effects of physical load on high school baseball players during midsummer games].

This study attempted to measure the physical load on high school baseball players during games played under extremely hot and humid conditions in the summer. The factors used to determine physical load were the following: body weight, oral temperature, blood pressure, heart rate, and serum biochemical elements. These were measured before and after the game. One hundred twenty-six baseball players from 7 high schools participated in this study. All the games were played under conditions of high temperature 34 degrees Celsius dry-bulb, 26 degrees Celsius wet-bulb, 41 degrees Celsius black-globe, 30 degrees WBGT, which are likely to cause heat-related illnesses. The results were as follows. 1) The physical load of baseball players during the game showed a 1.8 percent decrease in average body weight due to perspiration, a 0.35 degrees C increase in oral temperature and an increase in the heart rate. Examination of the serum biochemical elements showed that muscle deviation ferment changed due to muscular activity and blood condensed due to perspiration. The physical load levels of baseball players were influenced more by extreme heat than by exercise during the game. 2) The group of starting players showed higher body weight loss, oral temperature, heart rate, blood condensation and muscle deviation ferment levels than the group of players on the bench due to the difference in the length of exposure to summer heat and the amount of physical exertion. The changes in physical load levels during the game for the group of starting players were greater than those for the group for players on the bench. 3) Considering the changes in body weight, blood condensation and muscle deviation ferment, we can say that physical loads of players differed according to their positions, the pitcher having the greatest load, followed in descending order by the catcher, infielders, and outfielders. It has been recommended that high school baseball players should take different kinds of rest depending on their positions in order to recover from fatigue as soon as possible after a game.