CURRENT TOPICS IN SPORTS PODIATRY
How to Evaluate and Recommend Athletic Shoes AAPSM reviews the latest in athletic footwear.
By Karen A. Langone, DPM
This article is provided exclusively to Podiatry Management by the Ameri - can Academy of Podiatric Sports Medicine. The AAPSM serves to ad - vance the understanding, prevention and management of lower extremity sports and fitness injuries. The Acade - my believes that providing such knowl - edge to the profession and the public will optimize enjoyment and safe par - ticipation in sports and fitness activi - ties. The Academy accomplishes this mission through professional educa - tion, scientific research, public aware - more biomechanical con - ness and membership support. For ad - trol and biomechanical cor - ditional information on becoming a rection, to companies de - member of the AAPSM please visit our signing minimalist shoes, website at www.aapsm.org or circle to recommendations from #151 on the reader service card. some quarters that runners Figure 1: Shoe components should simply go barefoot. thletic shoe technology is It is important to keep in an ever-changing entity. Re - biomechanically, anatomically, and mind that competing ideas create Acent technological alter - sport-appropriate. improved footwear. We can surely ations to running shoes are the re - The American Academy of Podi - provide technological information sult of extensive research and dif - atric Sports Medicine (AAPSM) uti - to our patients, but the real art of fering views about what is best for lizes a four-point system, both to making recommendations lies in runners and athletes. Athletic shoes combining that information with are as diverse as the people who use an understanding of each individu - them; therefore, it is vital to under - al patient’s unique needs and cir - stand the differences between the cumstances. AAPSM’s four-point various types of shoes, such as system consists of reviewing the lit - those with cushioning, stability, erature, reviewing foot function, re - motion control, and the numerous viewing footwear construction, and models that are available. It is also then looking at footwear function imperative for the podiatric physi - as an evaluative process. cian to be aware of current trends Patients often ask, what is the in running shoes, including toning study and then allow us to recom - best running shoe for me? The an - shoes, barefoot running, and mini - mend shoes to our patients. The swer to that question is as diverse as malist running technology. Our need for evaluation is crucial, now the patient population. It is impor - goal as sports medicine podiatrists more than ever as we find ourselves tant to keep in mind that for every is to advise our patients as to the having to choose among many dif - foot there is a shoe. Through the athletic shoe that will allow them ferent competing concepts and years, we have seen multiple tech - maximum performance with mini - technologies—from companies nologies; some stay and some go. We mal risk of injury and that is also moving to create shoes with ever- Continued on page 108 www.podiatrym.com OCTOBER 2010 • PODIATRY MANAGEMENT 107 Athletic Shoes... fort. He also stated that footwear en - increased impact forces due to the hances performance through in - shoe bottoming out when loaded, remember Easy Coil shoes, the creasing traction and biomechanical and that firmer shoes were more Reebok Pump and Earth shoes as efficiency, and that footwear can preferential as they did not bottom trends that vanished with time. How - also reduce injuries by correcting for out. However, in 1987, they also ever, there are patients who liked the locomotor system static struc - showed that cushioning can reduce those shoes and felt that they im - tural misalignments. He goes on to impact forces, and the geometry of proved their individual conditions. say that footwear protects the foot at shoes can affect pronation in rear - In reviewing the research, Mario the interphase with the ground and foot strikers. Nigg further postulat - Lafortune from the Nike Sport Re - the entire body against the forces re - ed in the 2001 article in the Clinical search Laboratory published an arti - sulting from repeated foot ground Journal of Sports Medicine that the cle in September 2008 in Journal of impacts. Running shoe cushioning runner reacts to the combined con - Foot and Ankle Research in which he has proven to be both beneficial and ditions of a shoe sole orthotic or in - postulated that the three main detrimental to runners. sert cushioning and plantar recep - needs of the athlete are perfor - In 1981, Nigg, et al. showed tive surface, and accordingly ad - mance, injury protection, and com - that shoes with more cushioning justs muscle activity, fatigue, com - fort, work, and per - formance. Additional re - TABLE ONE search suggests that cushioning in run - AAPSM's 2010 Running Shoe Guide ning shoes can cause excessive sub - talar joint motion MAXIMUM STABILITY (Clement, et al., Asics Gel-Evolution 5 New Balance 1012 1981). A 1992 arti - Asics Gel-Foundation 8 New Balance 587 cle in the American Asics Gel-Fortitude New Balance 1123 Journal of Sports Brooks Beast Nike Zoom Nucleus MC+ Medicine by Brooks Ariel (women) Nike Zoom Equalon+3 Dressendorfer, et al. Brooks Addiction 8 Saucony ProGrid Stabil CS showed that reticu - Mizuno Wave Renegade 4 locytosis of the rearfoot was in - creased markedly in STABILITY runners who ran with a firm shoe Adidas Mizuno Wave Inspire 6 Adidas Supernova Sequence Mizuno Wave Elixir 4 versus those with a Asics Gel-3010 New Balance 760 more cushioned Asics Gel-Kayano 16 New Balance 850 shoe, and that ery - Asics GT -2150 New Balance 993 thropoietic activity Asics Gel-1150 New Balance 1225 was positively cor - Asics Gel-DS Trainer 15 Nike Structure Triax+ 12 related with peak Brooks Adrenaline GTS 10 Nike Lunarglide+ G-forces. Finally, Brooks Infiniti 2 Nike Air Span+ 6 Lieberman, et al. in Brooks Switch 3 Nike Zoom Elite+ 4 Nature in January Brooks Ravenna Saucony Progrid Omni 8 2010 looked at five Brooks Trance 9 Saucony ProGrid Hurricaine 11 Mizuno Wave Alchemy 9 Saucony ProGrid Guide 3 groups of runners and found that forefoot barefoot NEUTRAL strikers generated the lowest impact Adidas Adistar Ride Mizuno Wave Rider 13 forces versus shod Adidas Supernova Glide Mizuno Wave Precision 10 runners and bare - Adidas Response Cushion New Balance 1064 foot runners who Asics Gel-Nimbus 11 New Balance 883 were rearfoot strik - Asics Gel-Kushon 2 New Balance 905 Asics Gel-Cumulus Nike Air Pegasus+ 26 ers. However, for Asics Gel-Landreth Nike Air Max Moto+7 rearfoot strikers, Brooks Glycerin 8 Nike Zoom Vomero+ 4 running shod pro - Brooks Defyance 3 Reebok Premier Verona KFS II duced lower impact Brooks Ghost 2 Saucony ProGrid C2 Glide forces than running Mizuno Creation 11 Saucony ProGrid Jazz 13 barefoot. So, we are left with conflicting Continued on page 110
108 PODIATRY MANAGEMENT • OCTOBER 2010 www.podiatrym.com Athletic Shoes... research to date as to both the ben - efits of cushioning and various footstrike patterns and the forces correlated with each.
Foot Function The next component in evaluat - ing what shoe is best for the patient is looking at the patient’s foot func - tion. Evaluating foot function is certainly a complicated arena to enter. Although we have classically been instructed in the rigid high arch foot, the “normal arch,” and the low arch flexible foot, we all know that there is a greater contin - uum that exists with some patients Figure 2: Somnio customizable components having a high arch flexible foot and other patients having a low arched fit in shoes to their longest toe, op - sive review of shoe construction, rigid foot. Often, patients are told timally having a thumb’s width in describing the outsole upper and to evaluate their foot type by using space beyond the end of the mid-sole. The mid-sole lies between the “wet paper test.” In this test, longest toe to the tip of the shoe. the upper and the outsole and is the patient wets the foot and then Running shoe companies and usually composed of EVA or TPU. stands on a piece of paper and eval - running magazines use extensive The mid-sole is the most important uates the foot type that appears. sophisticated testing processes both part of the shoe in terms of cush - Minimal foot contact is indicative in the development and then in ioning and stability, and it deter - of the high arched foot, moderate the evaluation of the performance mines the cushioning and stability foot contact a normal arch, and full characteristics of the shoe, as well contact is indicative of a low arch. as the shoe’s functionality. Manu - Again, this evaluative process is facturers use their proprietary cush - flawed as it does not allow for pa - AAPSM’s four-point ioning systems within the mid-sole tients who fit outside these three foam. Most commonly, encapsulat - classic presentations and does not system consists of ed air gel or other materials are found in shoes such as the Nike Air, in any way take into account the reviewing the rigid flexible foot or the inflexible Asics Gel, Saucony Grid, Brooks flatfoot. This is where the expertise literature, reviewing DNA, etc. To date, there has been of the podiatric physician comes in no research which has shown the and our ability to evaluate each foot function, superiority of one type of material foot type. It is important to know reviewing footwear versus another. the foot type of the patient in order to match it with the best type of construction, and then Medial Post shoe for the patient. Classically Another important component speaking, the rigid high arched foot looking at footwear of the shoe is the medial post. This is going to go into a cushioned function as an is the firmer component within the neutral-type shoe, the normal mid-sole and is usually comprised arched patient is going to do best evaluative process. of a dual density EVA and can also in a stability shoe, and the flexible contain TPU, which is thermoplas - pes planus foot type is going to do tic urethane or carbon fiber. The best in a more stable shoe. function of the medial post is to de - of their shoes. Classically, flexion termine the stability of the shoe, Shoe Fit tests are done determining the flex - and the medial post dampens or Fit is also a major consideration. ibility of the shoe in the forefoot decreases the speed of pronation. Certain manufacturers make shoes and how smoothly it transitions Medial posts are found in all stabili - with widths that will better accom - from heel strike to toe-off. An im - ty and motion-controlled shoes, modate a wider foot structure; pact testing is done to evaluate the but are generally not found in some running and athletic shoes firmness of the shoes mid-sole. cushioned or neutral shoes. Their are constructed with deeper and Testing is also performed to evalu - benefit is to provide stability, but higher toeboxes, which will better ate the wear of the shoe and to de - they do add weight to the shoe. accommodate patients with ham - termine how long it will hold up The shank of the shoe stiffens the mertoe deformities. Fit in length is under use. On the Academy shoe under the arch area. Most run - also important. Patients should be (AAPSM) website, we do an exten - Continued on page 112
110 PODIATRY MANAGEMENT • OCTOBER 2010 www.podiatrym.com Athletic Shoes... ed, slip-lasted, and combination- lasted, as well as Strobel, which is ning shoes, except the most flexi - now the most common type of last ble, incorporate a shank which is construction utilized. In the Stro - usually constructed of urethane. bel-lasted shoe, a thin sheet of ma - terial or EVA is glued to the mid- Shoe Last sole, and the upper is stitched to The shoe last—the model over this. It is identified by stitching which the foot is constructed—de - around the perimeter of the foot scribes the shape of the shoe. Last bed, and it is a hybrid of the last shapes include curved, semi-curved, types (Figure 1). and straight. Curve-lasted shoes are The significance of shoe con - lighter, more cushioned, and offer struction is that mid-sole cushion - minimal resistance to pronation. ing stability devices, the last, and These are commonly found in rac - even the fit all add up to determine ing flats, competition spikes, and how much stability the shoe pro - cushioned and neutral shoes. On vides. This is essential in our ability the opposite end of the spectrum to evaluate an athletic shoe and to are straight-last shoes which, as determine the type of shoe based their name indicates, are straight. Figure 3: Newton shoes on the characteristics of its con - They resist pronation to a greater struction. This allows us to evaluate degree, are heavier, bulkier, and the curve-lasted. This last is typical - a shoe that the patient presents generally also incorporate a con - ly found in most running shoes. with, and therefore aid us in deter - trolling medial post. Straight-last The last also refers to how the mining if that shoe is appropriate shoes are found almost exclusively upper is attached to the mid-sole. for the patient. in motion-control shoes. A semi- The construction method utilized curved last is a hybrid of the two: here influences the stability, stiff - Function less controlling than the straight- ness, and flexibility of the shoe. The AAPSM fourth evaluated lasted, but more controlling than Most common types are board-last - Continued on page 113
112 PODIATRY MANAGEMENT • OCTOBER 2010 www.podiatrym.com Athletic Shoes... pronation resistance—and they are that we see today is towards bare - heavier and stiffer. Stability shoes foot and minimalist running. In step is to look at the function of are a hybrid containing semi- the category of semi-customization the footwear. Footwear is classified curved lasts; some have medial is the Somnio running shoe. Som - as maximum stability/motion con - posts and shanks. Neu - nios were tested at the Boulder trol, which then can be broken tral/cushioned shoes have no medi - Center of Sports Medicine and con - down into maximum, moderate, al post, are curve-lasted, have mini - tain various design components and minimal; stability; neu - mal pronation resistance, and are that allow semi-customization in tral/cushioned; minimalist and biomechanical correction. A shoe barefoot. Each shoe company gen - retailer must be qualified in order erates a “footwear comparison” to utilize the technology necessary chart for each season in which they to evaluate a runner for Somnios. list their shoe models versus their Markers are placed upon the competitors’ correspondingly classi - runner’s feet, legs, and hips. The fied shoe models. This footwear runner utilizes a treadmill, and a comparison chart can be obtained computer evaluates various angles by contacting any of the manufac - to determine how much biome - turers. The AAPSM web site also chanical correction this runner provides information as to shoe needs. The technician then utilizes model classification (those list - Figure 4: MBT rocker sole shoe this information to choose from ings—for maximum stabili - three full-foot varus wedges that are ty/motion control shoes, stability light and flexible. available, each with a different shoes, and neutral cushion shoes— An interesting phenomenon in amount of correction built in, three are listed here in Table One). The shoe design is that manufacturers foot beds each with different arch most popular shoes are stability are moving on the one hand to - heights, and cushioning inserts at shoes. Characteristics of the maxi - wards more high-tech, more biome - the first MTPJ and the heel. Somnio mum stability/motion control shoe chanical correction in the shoe attempts to customize shoes based are the largest, densest medial post, with semi-customization and com - on the functional needs of the indi - straightest last, and maximum puter feedback, but the major trend Continued on page 114
www.podiatrym.com OCTOBER 2010 • PODIATRY MANAGEMENT 113 Athletic Shoes... Unstable Shoes mentally friendly. Brooks has devel - The unstable shoe category, oped the Mogo mid-sole. Tradition - vidual (Figure 2). made popular by MBT shoes, al mid-soles can last up to 1,000 Another shoe technology that Reebok, and Skechers, is another years in landfill. This new material has gained popularity is the New - trend in athletic will change that ton shoe. The Newton shoe was de - shoes. This tech - 1,000 years to 20 signed specifically for mid- to fore - nology was devel - years, therefore foot strikers and actually contains oped based on making it more what are termed actuator lugs, the Masai, an environmentally which are raised rubber rectangles African tribe, and friendly. located in the forefoot of the shoe. how they walk in Born to Run At contact, the lugs are pushed into the sand. These by Christopher the mid-sole, where they stretch a unstable shoes are McDougall sug - membrane. At push-off, the mem - also termed ton - gests that run - brane rebounds and the actuators ing shoes. The ning long dis - are pushed from the mid-sole back theory behind tances barefoot is to the outsole, returning energy them is that they the key to happi - into the forward propulsion (Figure turn our flat hard ness and longevi - 3). Another shoe built along this artificial surface ty. McDougall similar philosophy is the Karhu, into a natural un - proposes that the which encourages minimal heel even ground, elaborate archi - contact time and embraces a ful - similar to walk - Figure 5: Nike Free tecture and cush - crum technology to return energy ing in sand. Due ioning of shoes is to the runner. to this change in function, these a cause of athletic injury. Mc - The pose run - shoes challenge Dougall bases this conclusion on ning method de - the core strength - his observations of the Tarahu - veloped by ening muscles to mara, a tribe noted for their ability Nicholas Ro - Patients should be more active. to run extreme distances in diffi - manov, a Russian This changed cult environmental conditions Ph.D., has been be fit in shoes to muscle action with relatively little injury. Born to advocated by its their longest toe, then creates good Run has created a devoted group of proponents to de - posture, and in - runners who have adopted this crease injury optimally having a creases shock ab - barefoot running trend, either in - rates in runners. sorption for the corporating it as part of their rou - This is a move - thumb’s width in joints, while sig - tine, or moving to training entirely ment method space beyond the end nificantly reduc - this way. The book is a vivid tale, based on main - ing musculoskele - but does take dramatic literary li - taining a particu - of the longest toe to tal compression. cense in its interpretation of the lar strike and This technology events that are portrayed. It has body position the tip of the shoe. appears to be very been, however, a best selling book where the runner similar to the and has generated an entire tech - lands on the ball rockerbottom nology behind it. of the foot, keeps technology used Keep in mind that once one the foot in an initial position and by pedorthists and podiatrists, but places any type of material upon does not push off, but rather pulls this new technol - the foot, one is the foot off the ground using the ogy is more ag - no longer run - hamstring and allowing gravity to gressive than ning barefoot. be the primary force in moving the those previous Research suggests The Nike Free was body forward. Romanov postulates corrections were. one of the first that it is the heel strike, present in The lack of mid- that cushioning shoes developed most runners, which is the cause of and forefoot mo - to address the most running injuries, and propos - tion in toning in running shoes needs of runners es his alternative method as a solu - shoes may help can cause excessive who wished to tion to these injuries. The use of patients with run with minimal the Newton and Karhu shoe fits mid-foot and subtalar joint support and cush - into this philosophy. Again, re - forefoot com - motion. ioning, with just search is conflicting in this matter. plaints, but one a protective cov - Multiple studies have shown no must be cautious ering for the foot. metabolic or functional advantages in placing a pa - The Free was de - for a runner who attempts to tient in such an unstable shoe (Fig - veloped with an extremely unique switch foot strike pattern. Gruber, ure 4). design, incorporating Sipes trans - et al. in 2009 in ACSM noted no There are even shoes now that verse fissures in the sole, which was difference in oxygen cost. are purported to be more environ - Continued on page 115
114 PODIATRY MANAGEMENT • OCTOBER 2010 www.podiatrym.com Athletic Shoes... of thoroughly evaluating the pa - Med. Sci. in Sports & Exercise (1987): tient’s anatomy, function, and in - 294-302. adapted from tire technology. This jury history cannot be overstated. Nigg, B.M., Bahlsen, H.A., Luethi, allows the entire shoe to roll up Knowledge and staying abreast of S.M. and Stokes, S. The influence of upon itself, so that there is very lit - current shoes and current tech - running velocity and midsole hardness on external impact forces in heel-toe tle support that comes from the nologies is essential for the sports running. J. Biomechanics (1987): 951- shoe. The shoe has what Nike terms medicine podiatrist. Even if one 959. a better anatomical shape design does not have an extensive sports Clement D.B., Taunton, J.E., Smart and is extremely medicine prac - G.W. & McNicol, K.L. A survey of some lightweight as the tice, one will not overuse running injuries. Phys mid-sole and the be able to get SportsMedicine (1981) :77-8. outsole are the through a day at Dressendorfer, et al. “Effect of Shoe same material, a The significance the office without Cushioning on the Development of phylon rubber of shoe construction encountering Reticulocytosis in Distance Runners.” blend. In addition some or all of American Journal of Sports Medicine (1992): 212-16. to the Free, Nike is that mid-sole these shoe issues. Lieberman, et al. “Foot Strike Pat - has developed the cushioning stability For patients terns and Collision Forces in Habitually Glide, in which it who wish to in - Barefoot Versus Shod Runners.” Nature incorporates 2 de - devices, the last, corporate unsta - (2010): 531-35. grees of varus cor - ble shoes or bare - McDougall, Christopher. Born to rection in the and even the fit foot running into Run: a Hidden Tribe, Superathletes, and shoe (Figure 5). all add up to their workout the Greatest Race the World Has Never Ecco has also schedule, it is best Seen. New York: Alfred A. Knopf, 2009. come out with determine how to always ap - Hamill, et al. “Lower Extremity Stiff - the Biom, which proach this as ness in Runners with Different Foot Types.” J Biomech. (2000). is more shoe than much stability one would ap - Grube, et al. “Metabolic Cost Of Al - the Nike Free, but the shoe provides. proach a new tering Foot Strike Patterns In Running.” still attempts to training activity Medicine & Science in Sports & adhere to this or training regi - Medicine 41.5 (2009): 512. barefoot philoso - men, with the Gruber, et al. “Segment Coordina - phy. The shoe gradual introduc - tion Response to Alterations in Foot most similar to actually being bare - tion of the new entity and constant Strike Pattern.” American Society of foot is the Vibram 5 Fingers shoe, monitoring should any problems Biomechanics (2009). Web. 8 May 2010. basically a rubber protective cover - arise. This will allow the patient to