Final answer:
The high-risk temperature range for continuous activities like endurance running, according to the wet bulb-globe temperature index, would be close to or exceed the upper limit of normal human body temperature tolerance, which is around 44°C. Specific high-risk WBGT values are not provided, but the safety threshold is inferred from the human body's narrow temperature tolerance.
Step-by-step explanation:
The wet bulb-globe temperature (WBGT) index is utilized to estimate the risk of heat-related illnesses during continuous activities, such as endurance running. The range of temperature that is high risk for these activities can be inferred from data concerning the narrow range of body temperatures that humans can safely tolerate. The human body normally maintains its core temperature close to 37°C, and variations in body temperature can indicate serious medical conditions. Therefore, an environment that pushes body temperature to extreme highs would fall into the high-risk category for endurance activities.
Although specific values for the WBGT index are not provided in the information reference, understanding that any significant increase in body temperature can be dangerous, a high-risk temperature range for such activities would likely be close to or exceed the upper limit of normal human body temperature tolerance, which is around 44°C. Considering human body temperature extremes and the importance of maintaining a safe core temperature during exercise, it is reasonable to assume that temperatures approaching these upper limits would not be safe for continuous, strenuous activity.