In Tennis Footwear - Part I December 2002 we reviewed basic footwear components and the objectives of an athletic shoe. Last month in Tennis Footwear - Part II we discussed tennis movements and the subsequent transfer of forces onto your foot and leg, shoe and surface interaction and the technology used to test shoe performance.

In this concluding column on tennis footwear we'll cover foot conditions and injuries, address specific questions readers submitted and note some interesting athletic shoe websites along the way.

Foot Conditions And Injuries Related To Footwear In Tennis

The wrong shoes can not only cause discomfort but can be the source of a multitude of conditions and injuries. I asked Dr. Marc Safran, orthopaedic surgeon, co-director of Sports Medicine at the University of California, San Francisco and Vice President of the Society for Tennis Medicine and Science (STMS), about common injuries seen in tennis related to footwear. The most common are "subungual hematoma (tennis toe), blisters, stress fractures, ankle sprains, corns and calluses," Safran reported.

Blisters, corns and calluses are caused by friction between the foot and the sock/shoe. The American Podiatric Medical Association (AMPA) suggests buffing corns and calluses with pumice after bathing and not using a sharp instrument to trim. (The APMA's web site has self-treatment instructions for many of these conditions as well as common injuries for other sports.) Their site also provides simple instructions to safely drain a blister (which should be done from the side - not the top) and specifically notes that the top skin (roof) of the blister should not be removed.

Tennis toe most often affects the second toe as blood accumulates under the nail. Typically caused by improper fitting shoes, the APMA suggests cool compresses and ice for mild cases of tennis toe and seeking a professional for draining more serious conditions.

The most common tennis injury is an ankle sprain. In many cases the foot turns inward, and causes pain and swelling on the outside of the ankle. Safran remarked, "[This happens] particularly if the shoes are not appropriate for the surface or you are not wearing tennis shoes. Contrary to common belief, there are special modifications for tennis shoes used for tennis versus cross trainers."

The APMA also has noted plantar fasciitis as a common problem in tennis. The plantar fascia is a supportive band of tissue in the foot. Plantar fasciitis occurs when stress on the bottom of the foot sometimes causes arch pain. The APMA suggests investigating different footwear and an orthotic device to place inside your shoe. (Orthotics are shoe inserts designed to help your feet maintain body alignment.)

Dr. Safran's offered some additional recommendations for injury prevention.

• Stretch, especially calf muscles.
• Warm up.
• Clear loose tennis balls from the court to reduce stepping or tripping on balls and spraining the ankles.
• Play in moderation. Do not advance training more than 10% per week.
• Wear shoes that fit appropriately - not too tight and not too loose. You need room for the toes, but if the shoes are too loose the feet slide around and create blisters and tennis toe.
• Wearing 2 pairs of socks can reduce blisters.
• Wear socks that wick away sweat.
• Dry feet and let shoes air out between play.
• Wear the socks you would normally wear with your tennis shoes when purchasing new tennis shoes.
• In terms of using an orthotic, flexible (no hard plastic), off the shelf orthotics were his preference.

Questions Submitted By Tennis Server Readers

Several of you wrote questions in and here is what we learned.

Question 1. Are there any temperature controlled court shoes available? I would like info on a shoe that would keep my foot at an even temperature while playing? I know that Footjoy has a golf shoe available but what about court shoes?

Pallis and Safran: Not that we know of, but we'd like one too! Adidas does have their "ClimaCool" tennis shoes with a ventilated mesh upper, sockline and sole. It is supposed to reduce heat, alleviate moisture build-up and cool the foot. Neither of us have tried the shoe though.

Pallis: I can no longer find the information on the Footjoy site but when the information was out there, this almost sounded like a shoe using thermo-regulating or "smart materials" (materials intended to adjust or compensate over a range of conditions). A colleague and I discussed this and he questioned whether a tennis shoe (with current technology) would benefit from this. Golf foot motions are clearly less quick, not as varied and more in contact with the ground and foot then in tennis and he questioned how workable this might be today.

Question 2. I wear Avia shoes because of the cantilever heel (my ankles are narrow and I used to have a tendency to roll my foot. Are there any other tennis shoes that use the cantilever technology? (This question came from a woman which influenced our answer.)

Pallis: A cantilever is a structure in which a beam or truss is projected. Typically (as in a cantilever bridge) there are two projecting beams or trusses opposite one another that join together. (Here's a picture of the cantilever section of the San Francisco-Oakland Bay Bridge. You can see it has a concave shape.)

The terms "Cantilever" and "Dual Cantilever System" are Avia registered names. In Avia's "Dual Cantilever System" there is a top and a bottom "cantilever". The top part of its "Dual Cantilever System" has a cup/concave shape and it does seem that a narrow heel would fit nicely into this shoe since it really surrounds the heel. In appearance, the bottom cantilever is almost a mirror image of the top. The bottom "Cantilever's" purpose is to "act like a trampoline ... to soften impact and stabilize the heel" according to the technology section of the Avia web site.

Women's feet are not just smaller than men's, they are shaped differently and in general are narrower. Additionally, the feet of women athletes differ from nonathletes. A woman athlete's foot is larger in the forefoot area and narrower in the heel than a nonathlete.

So the answer to this question is probably "No"; another manufacturer probably would not use the cantilever heel since it is a registered trademark of Avia. However, the footwear manufacturers all have to deal with the same problems, so I began to look for a similar technology.

New Balance has a "Graphite Rollbar" and "TPU (thermoplastic urethane) Posts" system which although a completely different technology appears would deal with some of the same heel rolling problems this reader asked about. New Balance is also known for having shoes in a wide range of widths including narrow sizes starting from 2A. However, although this is good news, I could not find a New Balance tennis shoe for women that used these technologies. One of their men's tennis shoes does use a "Graphite Rollbar".

One of the things I like about the New Balance site is that it documents the "last" it uses on each shoe in its product descriptions. A last is a foot model made of wood, plastic, or metal. For example this men's tennis shoe uses a Strobel last. Shoes are constructed based on this last model. In some instances the last model even has a narrow heel. (For more information see these men's and women's fit pages on the New Balance site.)

Safran: Most good tennis shoes have good heel counters to prevent rolling the foot. Also look for good upper banding and lacing pattern.

Question 3. I'm a 4.0 baseliner that plays about 2-3 matches a week, in the summer maybe 4 matches a week, so I'm playing a lot. I can go through a pair of new shoes, especially in the summer, in about 1-2 months. I play mostly hard courts and I wear the right inside toe out. It's so bad I've even worn away the shoe bottom on a pair of K-Swiss tennis shoes in one or two matches! To compensate for this expensive toe dragging I have to put plastic toe guards on this one side to protect the toe. I can go through about 5 boxes of these things in a summer! My question is, is there a shoe out there that is designed specifically for "big-time" toe draggers like me, without having to sacrifice foot comfort?

Safran: Sounds like this person is playing on "slow hard courts". Some shoes have more durable toe guards made of almost vulcanized rubber. The soft soled shoes have a tendency to wear through more quickly on the slow hard courts, so picking shoes with less friction characteristics and harder rubber may help. Some people just add shoe "goo" to the toe tips when it starts to wear out, especially when the bottom is still quite good.

Question 4. After a match my feet are killing me because of being on the balls of my feet most of the time. I've tried insole inserts and they help but the problem I face is if I purchase a shoe for comfort, I wear the toe out very quickly, if I purchase a shoe for toe protection and hard soles, my feet kill me. Isn't there a shoe available that will give me both of what I need?

Safran: Wearing cushioned inserts, not hard plastic, may help in the firmer shoes.

Question 5. Can you recommend a good insole for tennis. I'm wearing the best sock I can find, so what about insoles?

Safran: I like "1 Stop EVP" (from Foot Management with the catchy phone number of 1-800-HOT-FOOT).

Pallis: The Oregon Health and Science University's orthopedics group has also recommended this same product for knee pain. In flat-footed people an arch support can help with knee alignment and they recommended this same insole.

Question 6. Any thoughts on high-tops? I wear them now so I won't sprain my ankle again.

Safran: High tops can help reduce recurrent ankle sprains. However, many players do not use them as it can reduce mobility on the court. If you have never seen a physical therapist for ankle sprains, appropriate rehabilitation (even after years) is probably the best prevention for ankle sprains.

Pallis: Mid-cuts are more common and also are intended to provide greater stability for the ankle and should be well padded for comfort.

Question 7. (From Jani Pallis to Marc Safran) You've told me before that materials on the shoe sole should vary based on court surface. Can you expand on this?

Safran: A competitor who plays mostly from the baseline requires a shoe that has more sidewall support to stabilize the foot during the quick lateral, side-to-side, movements which are necessary. The baseline player also needs good support for forward and rear forces in addition to the extra sidewall support. The serve and volley player generates tremendous levels of forward forces in the forefoot or toe box area of the shoe. Without the appropriate shoe, these players are susceptible to developing tennis toe (subungual hematoma of the toe). Appropriate shoewear for these players includes a large toe box to provide adequate room so the toe will not slam against the end of the shoe.

Very seldom custom orthotics are necessary for the average player. Their shock absorption functions are not high, and foot control can be better maintained by flexible joints and muscular strength in the legs.

Natural rubber outersole provides excellent traction on all court surfaces. Polyurethane soles do not provide as much traction as natural rubber, and is usually only recommended for high traction court surfaces that provide exceptional footing, such as indoor carpet, where too much traction may result in injury. Lighter weight shoes, with less support, are more applicable to clay or composite courts, rather than hard courts.

Court surfaces have influences other than those regarding shoe wear and type. Different court surfaces can alter the demands that are placed on the tennis player. In general, clay courts and some synthetic courts slow the ball down and produce a higher bounce, allowing for longer points and longer matches. Because more strokes are hit in trying to impart more speed to a slower ball, there may be extra strain on the arm and back. The softer surfaces cushion the knees and legs reducing knee pain, particularly for arthritic knees, and reduce the likelihood of shin splints and lower extremity stress fractures.

However, since the softer surfaces result in longer matches, the extra running may put more demands on the legs resulting in muscular fatigue, and there may be more muscle strains from sliding on the soft surfaces. Achilles tendinitis occurs more commonly when switching to clay courts after playing predominantly on hard courts. Most synthetic courts and hard courts speed the ball up and keep the bounce lower, creating shorter points. However, because of the speed of the ball, more impact forces may be placed on the racquet and arm.

Similarly, the quick pace of the points on the harder surface may cause increased stress on the legs, such as shin splints and lower extremity stress fractures. This is particularly true when starting the hardcourt season after playing on clay courts for a prolonged period of time. Grass courts place an increased stress to the upper extremity due to the frequency of irregular ball bounces and an increased ball speed. The player must compensate for the fast moving ball that may bounce awkwardly and change their stroke mechanics to hit the ball. During prolonged practices and match play, this difference in repetitive stress is evident.

My thanks to the Tennis Server readers who submitted some great questions and Dr. Marc Safran for taking time to answer my and their questions.

Until next month ... Jani

References

The American Podiatric Medical Association, http://www.apma.org/sports/tennis.html.

Avia, "Dual Cantilever System" and "Cantilever System", http://www.avia.com/avia2003/avia.html.

New Balance, Tech Center Fit-Form for Men and Women, http://www.newbalance.com/techcenter/fitformsystem_men.html and http://www.newbalance.com/techcenter/fitformsystem_women.html.

The Oregon Health and Science University, Orthopaedics Patient Education, http://www.ohsu.edu/som-Orthopedics/dc_knee.htm.

Thanks to Jim Pallis for the cantilever bridge photo in this column.