Mizuno Breath Thermo
Mizuno has a fabric they call 'Breath Thermo' that generates heat, which seems ideal for Running in the Cold. The problem with this fabric is that it generates heat from your sweat and if you're sweating, your body is trying to lose heat. So Breath Thermo will generate heat when you least need it and not when you do. From a practical perspective, I tried the Mizuno Breath Thermo gloves and did not find them effective.
1 How does it work
Anyone with a physics background knows that the energy for heat has to come from somewhere, so how does Breath Thermo work? To understand, we need a bit of physics. As you may know, when a liquid evaporates, the process requires energy, which creates a cooling effect. That's how our sweat works to cool us. When the vapor condenses again, it releases energy, and that's where Breath Thermo gets its energy from. The idea is that you sweat, the sweat evaporates and this cools your skin. The sweat is then absorbed by the Breath Thermo which then releases the energy in the sweat vapor. This negates the cooling effect of the sweating.
2 Further reading
- The patent - http://www.patents.com/us-6216497.html
- The material, polyacrylate - http://en.wikipedia.org/wiki/Sodium_polyacrylate
- In the news - http://www.innovationintextiles.com/articles/775.php