From Fellrnr.com, Running tips
→Fellrnr Heat Suit
* Exercise in heat produces better acclimation than passive heat<ref name="ismj"/>, but passive heat (sauna) following exercise can also be quite effective<ref name="postsauna"/>.
==Fellrnr Heat Suit==
This 'heat suit' will allow for heat training even in quite cool conditions.
However, it works by preventing the body cooling itself, so it increases the risk of heat stroke. If you overheat wearing this heat suit, you will not cool off after you collapse. Please be careful taking this approach, and start off with very low intensity exercise. The key to the Fellrnr Heat Suit comes from two waterproof layers. A traditional sweat suit uses a single waterproof layer to trap your sweat and preventing it from cooling your body. The problem with the single layer is that the sweat soaks through any clothing and reduces the insulation. In cooler conditions the sweat soaked clothes can become chilly even with the waterproof layer. The Fellrnr Heat Suit approach traps the sweat away from the insulation layer, preventing this cooling effect. The Fellrnr Heat Suit has the following layers over both your top and legs: * A close fitting thermal layer near the skin. The purpose of this layer is to hold the sweat and keep your skin relatively comfortable. * A waterproof layer that traps the sweat in the first thermal layer. * An insulation layer, such as fleece that prevents any heat escaping. Because it is trapped between the two waterproof layers, it never becomes wet. * A second waterproof or windproof layer that traps the body's heat in the insulation layer. * In addition, wear hat, gloves and ideally a neck warmer or face mask. This combination will prevent the majority of heat escaping your body.
==The Science of Heat Acclimation==
For those who want to know more details about heat acclimation, here is a summary of the scientific data.