Description

A person running a marathon in a latitude greater than 40 degrees during the spring or early summer may not be acclimatized to warmer temperatures. This can result in a large number of people collapsing and requiring medical attention. Roberts developed an equation for estimating the number of runners who will not complete a course based on the wet bulb globe temperature (WBGT).

Marathon selection: run in a location at greater than 40 degrees latitude

Runner selection: non-elite regional resident, not yet fully acclimatized to a warmer temperature

Reasons for not completing the race:

(1) exertional heat illness

(2) dehydration

(3) overhydration with hyponatremia

(4) death

 Wet Bulb Globe Temperature Percent Unsuccessful < 1°C rises rapidly above 6% 1 to 13°C around 4 to 6% > 13°C rises rapidly above 6%

percent not completing the marathon =

= ((0.514 * ((WBGT)^2)) - 8.097 * (WBGT)) + 78.926) / 10

 Decision Level Temperature Percent Unsuccessful Do Not Start 20.5°C (69°F) 13% Caution 17°C (64°C) 9.5%

Limitations:

• The impact of altitude was not considered.

• This would not apply to a race run at a lower latitude or under other conditions.