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  • A person's feet modeling minimalist footwear Introduction“Minimalist footwear” has become popular of late, particularly in the running community. Personal experiences, lay articles, and research conducted on barefoot running have spawned the success of many different shoes, their common marketing theme touting their close approximation to training barefoot.

    In a recent survey of 6,082 runners, 75.7% of the 785 respondents indicated that they were at least somewhat interested in running barefoot or in minimalist footwear (11). The study also revealed that 30.4% had tried minimalist footwear, and 85.5% of those were likely to continue wearing minimalist footwear or going barefoot during training if they had sufficient instruction.

    The Mechanics of Minimalist FootwearWhile there are many variations, the basic structure of minimalist footwear is similar: little to no heel and extremely thin, flexible soles. This is contrasted with other types of shoes that use “barefoot technology” terminology, but actually have an unstable surface, such as a rocker-bottom shoe (shoe which has a thicker than normal sole with rounded heel) (7).

    Naturally the minimalist footwear trend has found its way into the strength and conditioning field, and professionals in this area must be aware of such trends, whether minimalists footwear is a fad or a long-term fixture within common practice.

    While there is little existing research data specific to minimalist footwear, much of the information assumes that it is indeed similar to going barefoot. This argument is debatable, considering the wide variation in minimalist footwear styles. It appears that with adequate adaptation time to barefoot conditions, runners consistently reduce their stride length, increase stride rate, decrease the range of motion of the ankle, knee, and hip, and adopt a more plantar-flexed position at foot contact (2, 13).

    Additionally, increased anticipatory muscle activity has been noted in plantar flexors during barefoot conditions (2). Peak impact forces in running are demonstrably reduced in barefoot conditions (2, 13), and running economy may be increased at race pace (4).
     
    Addressing Injury RatesMost of the conjecture on injury rates in barefoot vs. shod (with shoe) conditions is related to the changes in gait and degree of impact forces noted above. While little data exists to support such contentions, a recent review asserted seemingly little change in injury rates over the last 30 years, suggesting that the advances in shoe technology over that period did not reduce injury. In this study injury rates were adjusted for volume, and usually based on hours of activity to equalize (5).

    It is logical to hypothesize that running without a shoe, while not necessarily beneficial, would not be causally harmful if implemented correctly.

    The survey mentioned in the first paragraph (11) indicated that injury prevention was the primary motivating factor for running barefoot or in minimalist footwear, and yet 54% indicated that fear of injury was the primary factor in limiting running either barefoot or in minimalist footwear.

    Some have speculated that the soft soles of traditional modern running shoes may be responsible for injury due to the body’s adaptive response to landing on soft surfaces (10).

    The prior experience of test subjects with barefoot running is an important contributor to the findings of such studies. Several authors suggest feet that are routinely exposed to shod conditions are quite different from those that primarily go barefoot.

    Differences in pliability of the foot have been noted between habitual shoe wearers versus their barefoot counterparts (6), and in shoe-wearing children the rate of flatfoot is markedly increased even when controlling for age, obesity, and other factors (9,12).

    Research on Minimalist FootwearVery few studies have been done on minimalist footwear per se, although there was a study recently published that examined treadmill running in the Vibram FiveFinger™ (VFF) shoe in conjunction with barefoot and neutral-protective running shoes in experienced barefoot runners (13). Their general findings are similar to those discussed above, but interestingly there were still significant differences between the VFF and barefoot conditions for stride length, stride rate, step time and flight time.

    The VFF condition was, however, more similar to barefoot than to the normal shod condition, especially when considering the kinematics of the leg during running. The small sample size (n=8) may be a limitation to this study, but it may be difficult to recruit enough experienced barefoot runners to address this issue at this time. Therefore, there is still too little information to conclude that there is reason to opt for going barefoot over wearing VFFs or another type of minimalist footwear.

    In the same lab, proprioceptive sense was examined in 14 experienced runners under three conditions: VFF, barefoot, and traditional running shoes (14). The subjects were asked to predict the slope of a treadmill while running and the authors found the VFF wearers had significantly more accurate predictions of slope than the other conditions.

    Two other studies examined the VFF and appear as conference abstracts. Paquette et al. (8) examined 7 runners in similar conditions to the above study (13), but in this study over ground running was used in lieu of a treadmill. The findings largely simulate those above, again showing that VFF is more similar to barefoot than to normal-shoe conditions.

    While the minimalist footwear experience of this group is not noted, other studies have examined treadmill running in those who use the VFF or run barefoot a minimum of 10 miles/week (1). Each subject performed barefoot condition along with shod trials in both rearfoot and midfoot strike patterns (proper foot striking patterns may be dependent on minimalist footwear, barefoot, or shod conditions). Their preliminary data indicate that the barefoot running condition was most closely associated with the shod midfoot strike pattern (1).

    It should be noted that a transition to minimalist footwear may require a strategic, slow progression with regards to mileage and general use. A recent case report discussed two runners that developed metatarsal stress after adopting minimalist footwear (3). While cause and effect is impossible to determine, the authors speculated that the minimalist footwear was the cause, and that gait alterations and initial reductions in volume/pace are essential in a transition to training in minimalist footwear.

    Limited data exist on barefoot conditions in a non-running scenario that may have implications for other forms of exercise. The previously mentioned study by Squadrone and Gallozzi (14) also examined the ability of subjects to estimate the degree of plantarflexion, dorsiflexion, eversion, and inversion while a sloped board was placed under their feet.

    While the slope was underestimated in all static trials, the running shoe has the worst predictive ability, with no difference between VFF and barefoot.

    Minimalist footwear may actually have a benefit over the barefoot condition that they attempt to simulate. Surface hazards such as rocks, glass, etc. are just some of the safety issues encountered while training barefoot. Although minimalist shoes typically have very thin soles, they still may provide some protection against these hazards.

    Exposure to bacterial and viral agents as well asthermal stress may also be protected against by utilizing minimalist footwear, while still allowing for some of the purported benefits of training barefoot.

    ConclusionIt is clear that much more research is needed to determine the efficacy of minimalist footwear, particularly for sport and fitness training outside the realm of distance running. Several methodological concerns exist, making it harder still to accurately determine their benefits (and risks), including the limited number of study participants, the lack of uniformity among minimalist footwear designs, and the number of potential performance measures that have yet to be examined.

    One particular methodological concern with research on barefoot and minimalist footwear use is the experience the subject may already have with exercising either barefoot or wearing minimalist shoes. Data collected from subjects that are routinely shod and immediately going barefoot or minimalist may be quite different from the data on those who have had prior experience going barefoot or wearing minimalist footwear and have therefore already experienced adaptations to their stride, strike, and other measures accordingly.

    While many athletes are required to wear sport-specific footwear for competition and training, it is still possible that incorporating minimalist footwear into part of the training activity may lead to positive benefits for the athlete, such as improved running economy and improved proprioception.

    Regardless of what level or degree of training the athlete engages in, any incorporation of minimalist footwear into their training must involve a slow progression and regular monitoring to ensure a safe transition and avoid potential harm.
     
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    REFERENCES →


    1. Altman, AR, and Davis, IS. Comparing Barefoot Running to an Altered Strike Pattern in Shoes: 717: Board #1 8:00 AM - 10:00 AM. Medicine & Science in Sports & Exercise 43: 59 10.1249/01.MSS.0000402849.40481.5d, 2011. 
    2. Divert, C, Mornieux, G, Baur, H, Mayer, F, and Belli, A. Mechanical comparison of barefoot and shod running. Int. J. Sports Med. 26: 593-598, 2005. 
    3. Giuliani, J, Masini, B, Alitz, C, and Owens, BD. Barefoot-simulating footwear associated with metatarsal stress injury in 2 runners. Orthopedics 34: e320-3, 2011. 
    4. Hanson, NJ, Berg, K, Deka, P, Meendering, JR, and Ryan, C. Oxygen cost of running barefoot vs. running shod. Int. J. Sports Med. 32: 401-406, 2011. 
    5. Jenkins, DW, and Cauthon, DJ. Barefoot running claims and controversies: a review of the literature. J. Am. Podiatr. Med. Assoc. 101: 231-246, 2011. 
    6. Kadambande. - Comparative anthropometric analysis of shod and unshod feet. - Foot (Edinburgh, Scotland) 16: - 188--191, 2006. 
    7. Nigg, B. - Biomechanical considerations on barefoot movement and barefoot shoe concepts. - Footwear Science : - 73. 
    8. Paquette, M, Baumgartner, L, and Zhang, S. A Comparative Investigation Of Fivefingers With Barefoot And Shoes In Rear-foot Strikers: 718: Board #2 8:00 AM - 10:00 AM. Medicine & Science in Sports & Exercise 43: 60 10.1249/01.MSS.0000402850.48105.f1, 2011. 
    9. Rao, UB, and Joseph, B. The influence of footwear on the prevalence of flat foot. A survey of 2300 children. J. Bone Joint Surg. Br. 74: 525-527, 1992. 
    10. Robbins, S, and Waked, E. Balance and vertical impact in sports: role of shoe sole materials. Arch. Phys. Med. Rehabil. 78: 463-467, 1997. 
    11. Rothschild, CE. Primitive Running: A survey analysis of runners' interest, participation, and implementation. J. Strength Cond Res. , 2011. 
    12. Sachithanandam, V, and Joseph, B. The influence of footwear on the prevalence of flat foot. A survey of 1846 skeletally mature persons. J. Bone Joint Surg. Br. 77: 254-257, 1995. 
    13. Squadrone, R, and Gallozzi, C. Biomechanical and physiological comparison of barefoot and two shod conditions in experienced barefoot runners. J. Sports Med. Phys. Fitness 49: 6-13, 2009. 
    14. Squadrone, R, and Gallozzi, C. Effect of a five-toed minimal protection shoe on static and dynamic ankle position sense. J. Sports Med. Phys. Fitness 51: 401-408, 2011.