During physical activity we produce surplus heat and by perspiring, our body regulates its temperature. When the perspiration evaporates, the body temperature cools down. In case our clothing does not allow the perspiration to evaporate, there is hardly any cooling possible. Therefore, the layer closest to the skin must be perspiration transporting. If it is not, the perspiration will create an uncomfortable damp feeling. The second layer acts as an insulation layer. The third layer is the protection against the elements. However, the perspiration must still be allowed to pass from the inner layer though the next layers to the outside. The thinner the three layers, the more precise the regulation. If all layers are properly coordinated, they can work interactively with each other.
1st Layer: Regulation
The first layer should be fast drying functional underwear that transports moisture away from the body and on to the next layer. The faster moisture is transported away from the skin, the better the body temperature regulation works. Materials such as cotton should be avoided, because they absorb and store moisture (without allowing it to evaporate) and will make you feel damp and uncomfortable.