Winter in Canada is a cold and unforgiving time of year, when most people give up their favourite summer sports—like running and biking—in exchange for indoor alternatives. But combining exercise and the great outdoors is one of the best ways to beat the winter blues. So don't shy away from exercising outside just because it's cold out. There is technology to help you stay comfortable.
Although your first instinct might be to bundle up and keep warm on a winter run, remember that once you start moving you'll start sweating. In cold weather that sweat will coat your clothing, and then you'll be running in a cold, wet outfit. To avoid this, grab yourself some workout clothes with "wicking" abilities. What this means is that the clothing will absorb the sweat from your skin and disperse it to the surface of the fabric where it can evaporate quickly, leaving you warm and dry.
Is it magic? No, it's science! The movement of moisture through the spaces of the fabric is due to the combined effects of cohesion, adhesion, and surface tension (i.e. a process known as capillary action). The garment also employs the concepts of hydrophilia (love of water ) and hydrophobia (fear of water). In scientific terms they represent microscopic interactions between water and another molecule.
A water molecule is comprised of an oxygen atom sharing its electrons with two hydrogen atoms, but the sharing is not equal. Oxygen atoms have two more electron pairs than hydrogen. This means that oxygen ends up with a negative charge while the two hydrogen atoms have a positive one. When a molecule has two different charges within it, it is called polar, and it isn't happy. Atoms and molecules like to be balanced, so polar molecules will search out other polar molecules that they can form bonds with in an attempt to balance their charges. Since water is polar, fabrics that are water-loving (hydrophilic) are polar too.
On the flipside, hydrophobic fabrics are nonpolar, so they're already happy with their electrons and aren't going to share by making any bonds. Although the name hydrophobic implies that these fabrics repel water, it's actually the water that avoids the fabrics. A water molecule can't benefit from nonpolar, hydrophobic molecules, so it searches out other compounds to bond with (usually more H20 molecules). That's why water beads up and rolls off a duck's feathers or a waterproof jacket.
Fast Fact: Most natural fibers, like cotton, are hydrophilic. Most synthetic fibers, like polyester, are hydrophobic.
So how do you balance hydrophilic and hydrophobic fabrics to make the perfect sports shirt? One hundred percent hydrophilia will give you a sweat-soaked top that won't let the moisture evaporate, while 100 percent hydrophobic will give you a shirt that traps all your sweat against your skin. The best poly/cotton blends are about 85 percent hydrophobic and 15 percent hydrophilic. That's just enough to soak the sweat up from your skin, but the extra water-repellent fabric adds surface area for the sweat to spread out and evaporate.
Underneath Your Clothes: The science behind moisture wicking clothing and what it does.
Chemistry Tutorial: The chemistry of water
Water: to stick or not to stick [Video]
Kwon A, et al. 1998. Physiological significance of hydrophilic and hydrophobic textile materials during intermittent exercise in humans under the influence of warm ambient temperature with and without wind.European Journal of applied physiology and occupational physiology. 78 (6): 487-493.
Skinner, James S. 2005.Exercise Testing and Exercise Prescription for Special Cases: Theoretical basis and clinical application (3rd ed.). Baltimore, MD: Lippincott Williams & Wilkins.
Article first published January 23, 2012
Photo Credit:WolfgangE via Wikimedia Commons