http://static.americanrunning.org/fitnews/ARAfitnews_V28_3/index.html
OUR VIEW:
With personal and team experience with this topic, we at Eleet Fitness continue to preach the importance for athletes to acclimatize to the heat. As this article demonstrates, heat can significantly decrease performance. It is important to be knowledgeable about air temperature as well as the heat index (the combination of air temperature and relative humidity). The formula to determine heat index is somewhat complex so we will not go into detail on the calculations however is it important to know when the heat index has reached dangerous levels. Please use the information below to help identify dangerous heat index zones.
EFFECTS OF THE HEAT INDEX
27–32 °C 80–90 °F
Caution — fatigue is possible with prolonged exposure and activity. Continuing activity could result in heat cramps
32–41 °C 90–105 °F
Extreme caution — heat cramps, and heat exhaustion are possible. Continuing activity could result in heat stroke
41–54 °C 105–130 °F
Danger — heat cramps, and heat exhaustion are likely; heat stroke is probable with continued activity
over 54 °C over 130 °F
Extreme danger — heat stroke is imminent
