Ambient Conditions Prior to Tokyo 2020 Olympic and Paralympic Games: Considerations for Acclimation or Acclimatization Strategies

Abstract

The Tokyo Olympics and Paralympic games in 2020 will be held in hot and humid conditions. Heat acclimation (in a climatic chamber) or heat acclimatization (natural environment) is essential to prepare the (endurance) athletes and reduce the performance loss associated with work in the heat. Based on the 1990-2018 hourly meteorological data of Tokyo and the derived wet bulb globe temperature (WBGT) (Liljegren method), Heat Index and Humidex, it is shown that the circumstances prior to the games are likely not sufficiently hot to fully adapt to the heat. For instance, the WBGT 2 weeks prior to the games at the hottest moment of the day (13:00 h) is 26.4 ± 2.9°C and 28.6 ± 2.8°C during the games. These values include correction for global warming. The daily variation in thermal strain indices during the Tokyo Olympics (WBGT varying by 4°C between the early morning and the early afternoon) implies that the time of day of the event has a considerable impact on heat strain. The Paralympics heat strain is about 1.5°C WBGT lower than the Olympics, but may still impose considerable heat strain since the Paralympic athletes often have a reduced ability to thermoregulate. It is therefore recommended to acclimate about 1 month prior to the Olympics under controlled conditions set to the worst-case Tokyo climate and re-acclimatize in Japan or surroundings just prior to the Olympics.

Keywords: Olympics; WBGT; heat index; humidex; humidity; temperature; thermal strain.

FIGURE 1

Temperature (black squares) and relative humidity (open squares) (A), WBGT (B), HI (C), and Humidex (D) at hourly intervals based on meteorological data from the past 29 years (1990–2018) during the dates corresponding to the Olympic period (July 24th until August 9th). Vertical bars represent one standard deviation.

FIGURE 2

Temperature (black squares) and relative humidity (open squares) (A), WBGT (B), HI (C), and Humidex (D) at hourly intervals based on meteorological data from the past 29 years (1990–2018) during the dates corresponding to the Paralympic period (August 25th until September 6th). Vertical bars represent one standard deviation.

FIGURE 3

Temperature (black squares) and relative humidity (open squares) (A), WBGT (B), HI (C), Humidex (D) on the days prior to the start of the Olympics and Paralympics. Data is the mean (±SD) during the time period of 0800–2100 h obtained from hourly metrological data from the past 29 years (1990–2018). The Olympics period is coded on day 0 to 16 and the Paralympics on day 32 and 44; the former is in between the solid lines and the latter between the dotted lines. Vertical bars represent one standard deviation.

FIGURE 4

Temperature (black squares) and relative humidity (open squares) (A), WBGT (B), HI (C), Humidex (D) on the days prior to the start of the Olympics and Paralympics. Data is the mean (±SD) during the time period of 12:00–15:00 h obtained from hourly metrological data from the past 29 years (1990–2018). The Olympics period is coded on day 0 to 16 and the Paralympics on day 32 and 44; the former is in between the solid lines and the latter between the dotted lines. Vertical bars represent one standard deviation.

FIGURE 5

The probability of WBGT (50th and 95th percentile) being similar to the Tokyo 2020 Olympics on the days preceding the games at the following time periods: 08:00–11:00, 12:00–15:00, and 16:00–19:00 h.