High performance socks are designed to control two forces that affect a foot in motion: impact (the downward, percussive motion of the foot as it hits the ground) and shear (the force created when the foot slides forward and backward, and side to side, in the shoe). Impact and shear work together and separately to cause blisters, calluses and foot pain. Socks can dissipate impact and shear with judiciously placed padding.

But the most important thing a well-designed sock can do is dispense with the foot’s biggest enemy—moisture, which greatly increases the chances of contracting blisters, fungus and athlete’s foot, even warts. The key is to draw—or ‘‘wick’’—sweat away from the surface of the foot toward the inner surface of the shoe. The most effective way to do this is with specialised fibres.

Fibres generally fall into two categories: absorbent, such as cotton and wool, and water repellent, such as polyester and acrylic. In theory, fibres that repel water keep the foot drier by channeling moisture away from the foot. Fibres that retain water leave moisture next to the skin. Hence the popularity of synthetic fibres such as Coolmax, commonly used in high performance socks.

In addition to advanced fibre technology, manufacturers are mixing fibres strategically to accentuate wicking action. Today’s high performance socks may have a wicking fibre against the foot and an absorbent fibre on the outside to suck moisture away from the skin. (Janet Cromley)