48% of HS baseball games in Japan pref. in 2023 played at ‘no exercise’ heat indexes

SAITAMA — Nearly half of all 2023 Saitama prefectural high school baseball tournament games held in heat index tracking locations were played under conditions with a heatstroke risk level where the government recommends ceasing all physical activity, it has been learned.

From this year, the National High School Baseball Championship played at Hanshin Koshien Stadium in western Japan’s Hyogo Prefecture will introduce a split schedule with some games starting in the morning and others later in the day to avoid the worst heat. When it comes to regional tournaments, however, the game times are left to the discretion of the respective prefectural high school baseball federations. This has left those involved worrying about how to handle the situation.

Saitama Prefecture has sweltered under sizzling summer temperatures in the past, recording Japan’s highest temperature of 41.1 degrees Celsius in 2018. The heat index released by the Ministry of the Environment, known as the wet-bulb globe temperature, takes into consideration temperature, humidity and other factors to assess the risk of heatstroke. At a level of 31 or more, exercise is generally prohibited.

The Saitama Prefecture tournament of the national championship was held from July 8 to 28, 2023, at nine ballparks. The Mainichi Shimbun analyzed 110 games played at six venues in the four cities of Saitama, Koshigaya, Tokorozawa and Kumagaya, where the heat index is published by the Ministry of the Environment. (Thirty-four games played at three venues where the heat index is not released were not included in the analysis.)

This analysis showed that the heat index reached 31 or more during 53 games, or 48% of the total. Moreover, 90 games, or 82%, were played during times when the heat index rose to 28 or more, when “heavy exercise” is supposed to be suspended. Since the announcement of the end of the rainy season this year, cities in Saitama Prefecture have seen a succession of extremely hot days where the mercury has hit 35 C or above.

Measures have been put in place at regional high school baseball tournaments across Japan, such as moving up the starting time of games or introducing split sessions on a trial basis, but neither of these measures have been taken in Saitama Prefecture. Part of the reason is the tight schedule of the prefectural tournament, which is among the largest in Japan with around 140 teams participating, as well as a shortage of staff.

A prefectural high school baseball federation representative commented, “Final exams end around July 10. We have to get through all the games between that time and the end of the month.” With split sessions, the staff would be required to stay on hand for a longer time, and they would not be able to cover all nine stadiums. Measures are being taken against heatstroke, such as providing water breaks three times during games, but it remains difficult to take drastic measures.

Takaaki Matsumoto, a professor at Chukyo University whose fields of research include environmental physiology and who is familiar with heatstroke and sport-related issues, commented, “The heat index guidelines are created with club activities of general junior high and high school students in mind. They serve as a precautionary reminder to reduce accidents, and are not binding.” However, he added, “Even at a heat index of 28, there’s a considerable risk. Koshien, which has staffing and budget leeway, has moved ahead with measures, but it’s hard to thoroughly extend these all the way to regional tournaments. It’s important for each prefecture to adopt measures, but there’s a need to discuss the approach to the tournament, such as the possibility of holding it in autumn, before any fatalities.”

(Japanese original by Takuro Tahara, Saitama Bureau)