Read and respected by more doctors of chiropractic than any other professional publication in the world.

January 2003

Giving athletic patients a winning edge 

by Dr. Mark Charrette

Many common sports-related injuries occur at the foot and ankle, due to the high levels of force and repetitive stress such activities impose. Athletes, therefore, will usually benefit greatly from custom-made, flexible orthotics. Since you can often improve sports performance considerably by providing the right kind of lower extremity support, you should know what goes into a good orthotic for your athletic patients.

What works best?

Sports-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 man-made components. Are these new materials worth the expense? Let's see if they 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 which is generated up the leg into the knee, hip, and spine. The addition of carbon fibers helps plastics to flex better, thereby reducing some of the shock sent to the joints. Even better are the viscoelastic polymers, a group of man-made materials specifically created with the purpose of improving on the body's ability to dissipate shock stress to sensitive and easily damaged tissues.

Viscoelastic shoe inserts have been found to significantly reduce the reported pain levels in patients with low back pain.(1) Another study found that soreness in the Achilles tendon, calf, and back were significantly reduced by the use of shock-absorbing heel inserts.(2) Chronic knee pain due to patellofemoral pain syndrome has also been found to respond well to the use of soft orthotics made with viscoelastic polymers. (3)

***  Weight reduction

In most sports, the amount of weight lifted at each foot lift-off is an important performance factor. Therefore, a good shoe orthotic increases the weight of an athlete's shoe only slightly. Reduced weight is a major reason why viscoelastic polymers have been so readily accepted by athletes.

***  Fit

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 the shoe," which would distract from sports performance. The newer materials seem to be more comfortable. There is a much shorter break-in period, and the athlete easily becomes accustomed to sports orthotics constructed from viscoelastic polymers.

***  Corrective support

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. Additionally, the orthotic should help improve gait,(4) knee alignment,(5) and both balance and the proprioceptive feedback system.(6) 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 the natural biomechanical performance. Torsional rigidity (the ability of the orthotic to resist twisting) combined with longitudinal flexibility (especially at the forefoot) are major indicators of a good sports orthotic. I would characterize such an insert as a firm-yet-flexible orthotic.

***  Durability

Unless you are working with a highly paid athlete, cost and durability are major 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; and 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 provide the needed factors of shock absorption, light in weight, fit, support, and durability. While the cost of these materials is a little more, the benefits are also much greater. However, the materials do need to be integrated into an appropriate design with skilled construction. Athletic patients should not settle for lesser orthotics. When you provide your active patients with properly fitted, custom-made orthotics, they'll perform better, and your practice will grow.

References

1. Voloshin A, Wosk J. "An in vivo study of low back pain and shock absorption in the human locomotor system." J Biomech 1982; 15:21-27.

2. Faun P et al. "Soreness in lower extremities and back is reduced by use of shock absorbing heel inserts." Int J Sport Med 1993; 14:288-290.

3. Eng JJ, Pierrynowski MR. "Evaluation of soft foot orthotics in the treatment of patellofemoral pain syndrome." Phys Ther 1993; 73:62-70.

4. Stude DE, Gullickson J. "Effects of orthotic intervention and nine holes of simulated golf on gait in experienced golfers." J Manip Physiol Ther 2001; 24(4):279-287.

5. Kuhn DR, Yochum TR, Cherry AR, Rodgers SS. "Immediate changes in the quadriceps femoris angle after insertion of an orthotic device." J Manip Physiol Ther 2002; 25(7):465-470.

6. Stude DE, Brink DK. "Effects of nine holes of simulated golf and orthotic intervention on balance and proprioception in experienced golfers." J Manip Physiol Ther 1997; 20(9):590-601.