This study aimed to describe the injury profiles of young Korean baseball players according to position and age as the proportion and distribution of injuries based on playing position and age remains unclear. A total of 271 elite youth baseball players aged 8 to 16 years were divided into two groups: elementary school (ES) (n=135) and middle school (MS) (n=136). The participants' basic, baseball practice, and injury information were collected. Injuries in the MS group were not limited to the elbow and shoulder, and the injury prevalence varied by age group and baseball position. The most injured body region in the ES group was the elbow joint, regardless of the position. In contrast, the most injured body region in the MS group was the lower back, except for infielders whose elbows were the most injured. Additionally, the MS group was more likely to experience injuries of the lower back (OR=4.27, 95% CI=2.47–7.40), shoulder (OR=1.93, 95% CI=1.08–3.43; P=0.024), and knee (OR=2.15, 95% CI=1.17–3.94; P=0.012). Our findings indicate that excessive practice and lack of rest during MS (growth spurt period) can significantly increase the risk of lower back problems in young baseball players.

A summer high school baseball tournament is held every mid-summer in Koshien Stadium. “Koshien Baseball” is very popular in Japan; however, it faces the problem of extremely high temperatures during games. Thus, high school players are threatened by the harsh environment. For this reason, Internet surveys were conducted twice to purposefully engage the same individuals. Then, information on their views regarding the Koshien tournament before and after the provision of information regarding environmental change in Japan was gathered. Using data, this study examined how their views changed after having the information. Compared with the view before, it was found that (1) respondents were more likely to agree that the management rule of the Koshien tournaments should be altered to protect player’s health, and (2) the impact of providing information is larger for female respondents, young people, and highly educated respondents.

This study measures the noise levels in a baseball stadium and analyzes baseball fans’ attitude of effect of recreational noise exposure on their hearing. In the baseball stadium, noise levels were measured in four seating sections using a sound level meter during the games. The LAeq average of the 16 measures produced 91.7 dBA, showing a significantly high noise level in the red and navy sections. As a function of frequency by LZeq analysis, the noise levels were significantly higher in low frequencies than other frequencies. For the survey sample, 688 randomly selected participants completed a 16-question survey on their noise exposure during the game and on the potential risk of hearing loss. Despite the very high noise levels, 70% of the respondents preferred sitting in either the red or the navy section to be closer to the cheerleaders and to obtain a good view. Most respondents reported that they did not consider wearing earplugs, and one-third experienced hearing muffled speech after the game. We conclude that the noise levels in baseball stadiums are high enough to cause hearing damage and/or tinnitus later, but expect these results to improve public education regarding safe noise exposure during popular sports activities.

In this article, the multitouch option, also called the n  touch option (or the “baseball” option when n  3 ) is analyzed and valued in closed form. This is a kind of barrier option that sets a gradual knockout / knock-in mechanism based on the number of times the underlying asset has crossed a predefined barrier in various time intervals before expiry. The higher the number of predefined time intervals during which the barrier has been touched, the lower the value of a knock-out contract at expiry, and conversely for a knock-in one. Multitouch options can be viewed as an extension of step barrier options, preserving the ability of the latter to adjust the exposure to risk over time, while eliminating the notorious danger of “sudden death” that holders of step barrier options are faced with. Unlike occupation time derivatives, the payoff at expiry does not depend on the amount of time spent outside the authorized range, but on the number of passages beyond the authorized range.