"Your choice of athletic socks is also important. Sports podiatrists frequently recommend appropriately padded socks of acrylic fiber. Acrylic fibers tend to 'wick' away excessive perspiration, which active feet can produce from 250,000 sweat glands at a rate of four to six ounces a day, or even more."
Per the American Podiatric Medical Association site.

Athlete’s Foot: It is not easy to prevent athlete's foot because it is usually contracted in dressing rooms, showers, and swimming pool locker rooms where bare feet come in contact with the fungus. However, you can do much to prevent infection by practicing good foot hygiene. Daily washing of the feet with soap and water; drying carefully, especially between the toes; and changing shoes and hose regularly to decrease moisture, help prevent the fungus from infecting the feet. Also helpful is daily use of a quality foot powder. Tips:

• Avoid walking barefoot (in public locker rooms); use shower shoes.
• Reduce perspiration by using talcum powder.
• Wear light and airy shoes.
• Wear socks that keep your feet dry, and change them frequently if you perspire heavily.

Per the American Podiatric Medical Association site.

"Foot Problems." In The Complete Guide to Symptoms, Illness and Surgery. 3rd ed. Ed. H. Winter Griffith, et al. New York: Berkeley Publishing, 1995.

"The ability of a sock to dissipate damaging forces on the surface of the foot rests partly on the fiber composition and more significantly on the construction technique of the manufacturer. It is the lack of understanding of fiber technology that leads most health care professionals to make erroneous recommendations to their patients regarding selection for sporting activities.

Fibers that absorb moisture are termed hydrophilic while fibers repelling moisture are hydrophobic. Cotton fiber retains three times the moisture of acrylic and fourteen times the moisture of CoolMax®. When exposed to ambient air, socks composed of cotton retain moisture ten times longer than acrylic. In descending order of hydrophilic ranking, the following fibers are listed: cotton, wool, acrylic, CoolMax®, polypropylene.

During initial activity, moisture absorption from the feet becomes a desirable feature. In athletic activity, perspiration output on the feet can exceed one pint per foot. A large part of this moisture may actually accumulate in the feet as it is produced elsewhere on the body surface and drips down the legs due to gravity. Nonetheless, this volume of fluid far exceeds the absorptive capacity of any sock product. Therefore, to minimize moisture accumulation on the skin surface, the sock must set up a wicking gradient to the shoe.

Ideally, a wicking gradient occurs when the shoe upper is breathable (i.e., nylon mesh) so that ambient air encourages evaporation of water vapor. More commonly, a shoe liner or upper will contain hydrophilic fibers that draw moisture from the hydrophobic sock material. Socks that are extremely hydrophobic (i.e., polypropylene) are thought to repel water so effectively that wicking cannot occur. Socks of intermediate hydrophobic range, i.e., wool and acrylic, allow movement of water but will not absorb and retain water like cotton fibers will. Degrees of hydrophobic qualities alone, however, don’t determine overall wicking capacity.

The mechanical structure of the fiber and compressibility of the fiber will determine overall wicking potential. CoolMax® fibers have four channels built into their cross-sectional geometry giving a 20% higher perimeter area than traditional round fibers. The result is higher water/vapor transport through enhanced surface exposure for capillary action.

Natural fibers (cotton-wool) when laden with moisture, compress more easily than synthetic fibers (acrylic, CoolMax®). Thus, cotton and wool socks have a higher resistance to sweat transport of wicking. When wet, acrylic fibers swell less than 5% while cotton swells 45% and wool swells 35%. Swollen fibers that are compressed reduce air spaces and thus reduce moisture transport. Thus, cotton socks exhibit a 2.4 times higher resistance to moisture transport.

When combining hydrophobic qualities and mechanical fiber qualities, the fibers that wick moisture best are, from best to worst: CoolMax®, acrylic, polypropylene, wool, cotton.

In studies conducted on runners wearing synthetic fiber socks vs. cotton socks, other significant differences surfaced regarding preferability of fiber composition. Cotton fiber socks, when wet, were observed to stretch and lose their shape inside the shoe. This led to bunching and wrinkling of the socks compared to acrylic fiber socks. After multiple wash-wear cycles, cotton fiber socks were noted to become abrasive leading to potential irritation on the skin surface of the athlete.

In some sport applications, the thermal-insulation quality of the fiber composition becomes critical. New synthetic fibers composed of a hollow core material known as Thermax have been shown to effectively insulate against heat loss. Natural wool fiber socks are still preferable in the outdoor industry because of their remarkable ability to maintain heat while wet. However, the abrasive nature of 100% wool fiber socks has required the blending of wool into other high-tech synthetic fiber materials."

. . . . . . . .

"Herring and Richie investigated the role of fiber and sock construction techniques in the prevention of blisters on the feet of running athletes. Their findings demonstrated that acrylic fiber socks will have less blisters and smaller blisters than cotton fiber socks. In addition, athletes were able to determine a drier foot with acrylic socks compared to cotton."