Most recreational and competitive sports impose high levels of force and repetitive stress on the lower extremities. Many common sport-related injuries occur at the foot and ankle. Athletes, therefore, will often benefit tremendously from well-fitted, custom orthotics. Since you have the ability to improve sport performance considerably by providing the right kind of lower extremity support, let's review what goes into a good orthotic for your athletic patients. Whether walking or running, playing golf or baseball, or involved in soccer or skating, active patients need expert advice regarding custom shoe inserts.
A Variety of Materials
Sport-oriented orthotics have come a long way from the days of steel, leather, and rigid plastic. Materials available today include carbon fibers, viscoelastic polymers, and numerous trademarked artificial components. Are these really worth the expense? Let's see if these new materials address some of the most important requirements for a sports orthotic.
Shock absorption. Most of today's sports orthotics are carefully designed to reduce the shock wave generated up the leg into the knee, hip and spine. The addition of carbon fibers helps plastics flex better, thereby reducing some of the shock sent to the joints. Even better are the viscoelastic polymers, a group of synthetic materials specifically created with the purpose of improving on the body's ability to dissipate shock stress to sensitive and easily damaged tissues.
Voloshin and Wosk found that viscoelastic shoe inserts significantly reduced the reported pain levels in patients with low back pain.1 In another report, a controlled study on soccer referees participating in a five-day tournament found that soreness of the Achilles tendon, calf and back were significantly reduced by the use of shock-absorbing heel inserts.2 Chronic knee pain (patellofemoral pain syndrome) has also been found to respond well to the use of soft orthotics made with viscoelastic polymers.3
Weight. In most sports, the amount of weight lifted at each foot lift-off is an important factor in performance. A good sport orthotic must therefore increase the weight of an athlete's shoe only minimally. Several newer materials are lighter in weight than the traditional plastics, leather and cork. Reduced weight is a major reason that carbon fibers and viscoelastic polymers have been so readily accepted by athletes. Good orthotic construction may also take advantage of inventive manufacturing techniques to lose weight, such as holes punched in the material to decrease the density. These "pores" also serve to transmit heat generated during exercise.
Comfort. Obviously, fit is a tremendously important factor. A good sport orthotic must fit easily into the athlete's shoe with a minimum of modification. There must never be a sensation of "something in my shoe," which would distract from sports performance. The newer materials seem to be more comfortable and less annoying. There is a much shorter break-in period, and the athlete easily becomes accustomed to sports orthotics constructed from carbon fibers or viscoelastic polymers.
Performance. The best orthotic for an athlete is one which will improve the function of the foot and ankle during complex and strenuous sports endeavors. This means controlling the amount of pronation, supporting the arches, and preventing excessive ankle and calcaneus eversion. Meanwhile, there must be little or no interference in the proprioceptive feedback system, and the foot and ankle must be in good balance. The entire foot, ankle, and lower extremity must have excellent mobility to respond immediately to changes in posture and alignment.
An orthotic used during sports must be supportive, yet flexible. It has to provide guidance for the foot and ankle, but must not hinder natural biomechanical performance. Torsional rigidity (the ability of the orthotic to resist twisting) combined with longitudinal flexibility (especially at the forefoot) seem to be the major indicators of a good sports orthotic, in my experience. I would characterize such an insert as firm-yet-flexible.
Durability. Unless you are working with a highly paid athlete, cost and durability are tightly interwoven considerations. Since athletic endeavors produce higher forces and stresses on an orthotic, it must be capable of sustaining physical "insults" repeatedly, with no perceptible decrease in performance or shock absorption. Moisture and heat must not cause significant degradation of any of the above factors. Once again, the newer materials are usually the most durable; when proper care is taken, their physical characteristics can be maintained for a long time.
Conclusion
The newer materials used in most sport orthotics are not just sales gimmicks. They do provide the needed factors of shock absorption, light weight, comfort, performance, and durability. While the cost of these materials is somewhat more, the benefits are also much greater. The materials need to be integrated in an appropriate design with skilled construction, however. Athletic patients should not settle for lesser orthotics. When you provide your active patients with properly fitted custom orthotics selected particularly for their sports, they'll perform better, and your practice will grow.
References
- Voloshin A, Wosk J. An in vivo study of low back pain and shock absorption in the human locomotor system. J Biomech 1982;15:21-7.
- Fauno P, et al. Soreness in lower extremities and back is reduced by use of shock absorbing heel inserts. Int J Sport Med 1993;14:288-90.
- Eng JJ, Pierrynowski MR. Evaluation of soft foot orthotics in the treatment of patellofemoral pain syndrome. Phys Ther 1993;73:62-70.
Mark Charrette,DC
Las Vegas, Nevada
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