Understanding the risks involved in training in hot climates (25 °C+) and high humidity

Training in hot weather (over 25 °C) puts extra stress on your body. If you don't take care when exercising in the heat, you risk serious illness.   When you training in the heat your body sends more blood to circulate through your skin. This leaves less blood for your muscles (reduction in oxygen), which in turn increases your heart rate. If the humidity also is high, your body faces added stress because sweat doesn't readily evaporate from your skin. That pushes your body temperature even higher.  Both the exercise itself and the air temperature and humidity can increase your core body temperature.