Foot Blister Prevention: What You Can Recommend To Athletes

By Mark A. Caselli, DPM, and Jean Chen-Vitulli, DPM

Foot blisters are among the most common injuries for athletes. According to research from the Scholl, over 5.2 million people suffer blisters every year. In a study of lower extremity injuries that occurred at the New York City Marathon, the most common foot problems reported were acute shear and stress injuries resulting in blister formation. Aside from being painful, blisters can alter an athlete’s running form and lead to even more serious injuries of the leg and hip due to irregular gait biomechanics. Blisters result from frictional forces that mechanically separate epidermal cells at the level of the stratum spinosum. Hydrostatic pressure causes the area of the separation to fill with lymph-like fluid. The magnitude of the frictional forces and the number of times an object cycles across the skin determine the probability of blister development. The higher the frictional forces, the fewer cycles are necessary to produce a blister. Moist skin increases frictional forces, leading to blister formation, while very dry or very wet skin decreases frictional forces, preventing blisters. Other risk factors for foot blister formation include ethnicity (African-Americans are at lower risk than others), flat feet and feet with structural prominences, such as bunions, hammertoes and Haglund’s deformity. Tips About Shoes, Insoles And Socks You Can Pass On To Patients In order to prevent blisters, we need to minimize friction. This begins with shoe selection. Emphasize to patients that their shoes should fit comfortably, with about a thumb’s width (3/8-inch to 1/2-inch) between the longest toe and the end of the shoe. Narrow shoes can cause blisters on the hallux and fifth toe. A shallow toe box can lead to blisters on the tops of the toes, while loose shoes often create blisters on the tips of the toes. Shoes should be sport specific. When trying on shoes, athletes should wear the same sock, insoles or orthotic inserts they wear when playing or working out. Encourage them to get shoes fitted in the afternoon or evening, since feet tend to swell during the day. Athletes should wear their shoes around the house for one to two hours to identify any areas of discomfort. It often helps to break in shoes by wearing them for one to two hours on the first day of sports activity and gradually increase use each day. However, even if shoes fit well, the insoles (or sock liners) could cause problems if they have worn out or flattened down. Remind athletes to check the condition of the insoles periodically and replace them if necessary. A new OTC insole (such as those manufactured by Spenco Medical Corporation) can keep friction to a minimum. Also encourage runners to examine the inside of footwear for seams or rough areas that often correspond to the sites of blisters. Emphasizing the proper socks also can decrease friction and prevent blister formation. Socks made from synthetic blends are best. Socks made from polypropylene or other new synthetic materials can wick moisture away from the skin more effectively than wool or cotton, further decreasing the likelihood of blisters. Layering socks or special double-layered socks can further minimize shearing forces. If your athletes wear socks with large toe seams, tell them that wearing the socks inside out can help prevent blisters on the tops of their toes. It is also a good idea for athletes to carry an extra pair of socks to change into if their socks become too damp. A Review Of Helpful Lubricants And Drying Agents When athletes have areas of the feet that are prone to blistering, applying lubricants (like petroleum jelly, bag balm or even dry soap flakes) before they put on socks helps reduce friction. Athletes should reapply large amounts of petroleum jelly every 10 miles during long walks or running events. Instead of petroleum jelly, some athletes prefer applying non-petroleum anti-chafing lubricants, such as BodyGlide (W. Sternoff, LLC) or Runner’s Lube (Mueller Sports Medicine, Inc.), prior to a long distance walk to prevent blisters. These products are waterproof, perspiration-proof, non-greasy, and wash off with soap and water. Another recommendation is to massage both feet with lanolin every night for a month before a big walking or running event. It’s better than petroleum jelly since it doesn’t create heat when friction occurs. It is also a good barrier for water in case it rains during the event.

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