A fabric's ability to allow water vapour created by the body to escape When you do exercise (sportsperson or not) your body produces heat.
To regulate the temperature, humans have a means of evacuating this excess heat: perspiration.

When practising a sport outdoors, you can quickly feel the discomfort when you produce an intense or sustained effort (excess heat, sweat etc.). Wearing non-breathable clothing maintains this phenomenon as the water vapour generated by perspiration accumulates between the body and the jacket.
 
This is why it is essential to dress by superposing textile layers suited to your activity (according to the type of sport and the outdoor conditions) including a waterproof and breathable layer for protection against bad weather.
 
Using products with breathable fabrics allows water vapour to evacuate from the clothing so that a feeling of comfort accompanies the sportsperson throughout his/her activity.

NOVADRY technology wicks away the water vapour your body generates naturally to the outside of the fabric.