Running continues to be an increasingly prevalent and effective way of achieving fitness and promoting long-term exercise. According to the National Sporting Goods Association, 35.5 million Americans participated in jogging or running in 2010, a 10.3% increase in the past 2 years (13). Of these runners, close to 1.3 million participate in running races with distances ranging from the 5k to that of the marathon. Other people participate in running as a functional part of their lives and occupations or simply for fun (18).
Estimates suggest that humans began running nearly 2 million years ago as the skeletal structure and muscular specializations of bipedalism allowed humans to run and compete with other scavengers for food. This evolutionary need may have facilitated endurance running and contributed to the development of the human body form (3). These early humans most likely ran barefoot or wore protective, insulating footwear coverings such as moccasins or sandals. Running evolved into a competitive sport as athletes raced the first foot race in the ancient Olympic Games in Olympia, Greece, in 776 B.C. As the sport of running gained popularity, runners were in need of advanced shoe wear to improve performance. The 18th century saw the development of a light-weight running shoe, which could grip the ground (17). This was quickly followed by the creation of an all-leather spiked shoe in the 19th century, which provided improved traction and performance (17). The foundation for the modern running shoe offering additional support and lacing later followed in the 1920s (17). The modern running shoe evolved in the 1970s to offer greater comfort and durability through mesh upper construction and increased cushioning for the toes, heel, and ball of the feet. The current selection of running shoes offers an immense array of stability and cushioning from various shoe brands (17).
Despite the innovations in shoe technology, there has been a recent movement promoting running barefoot or in light, “minimalist” shoes. Advocates of barefoot running believe that returning to the way our primal ancestors ran may result in fewer running-related injuries. The majority of these reports, though, are anecdotal in nature. The Barefoot Running Society, founded in the United States, has close to 2000 members internationally and is growing annually (1). Research has not clearly identified why runners choose to run barefoot or in minimalist shoes, and a survey study of runners has been recommended (9). Little is known about the characteristics of these runners, their use and expectations of barefoot or minimalist shod running, or how these running styles are implemented. Additionally, no studies to date have demonstrated the safest or most effective method for implementing a barefoot running program (9).
Runners who are interested in or who have participated in running barefoot or in minimalist shoes may be characterized by gender, age, training and racing experience, and history of injury. Additionally, runners may have specific implementation methods and rationale for running barefoot or in minimalist shoes. The purpose of this study is to investigate the current interest level, participation, and implementation of barefoot or minimalist shod running among a population of runners. In addition, the study will examine runner demographics, motivating factors, used resources, perceived barriers, and expectations in runners who add barefoot or minimalist shod running to their training program. Information from this study can help identify current practices and, thus, assist the running professional and coach in understanding relevant factors and designing instructional training programs for those desiring to run barefoot or in minimalist shoes.
Experimental Approach to the Problem
An electronic survey was created by the author via SurveyMonkey (SurveyMonkey, Palo Alto, CA, USA). The survey consisted of a total of 26 questions in both open and closed-question formats. Responses to 16 of the questions were required. Determining the dependent variables of interest level and participation in barefoot and minimalist shod running was of importance. Questions revealing information about the independent variables including gender, age, average weekly mileage, self-perceived running level (SPRL), longest race completed in the past 6 months, and longest race distance planned to complete in the next 6 months were required. Identification of recent running-related injury including body part location and resulting time frame unable to run were requested. Additionally, questions aimed to identify resources used, perceived barriers, adverse reactions, preferred resources, and implementation characteristics of the respondents' transition to barefoot or minimalist shod running.
Seven hundred eighty-five (415 female, 370 male) people completed the survey (13% response rate). Of the 785 survey respondents, the majority (60%) were between 30 and 49 years of age (n = 471). Three hundred sixty-four (46.4%) described themselves as recreational runners, 380 (48.4%) described themselves as competitive amateur runners, and 41 (5.2%) described themselves as elite runners. In reporting weekly running mileage, most respondents (84.6%, n = 664) reported running <30 miles per week. The half-marathon was the longest race distance completed by most runners in the past 6 months (35%, n = 275) and the longest race distance respondents planned to complete within the next 6 months (41.3%, n = 324). All the subjects were informed of their choice to voluntarily participate and freedom to deny answering specific items. The study protocol was reviewed and approved for conduct as exempt from the requirement for obtaining written informed consent from the University of Central Florida Institutional Review Board.
The survey was distributed to 6,082 runners randomly selected from a database of people who had participated in a running race sponsored by the Track Shack, a running specialty store in Orlando, Florida, within the previous 18 months. An e-mail from the Track Shack (Orlando, FL, USA) was sent to the runners with a brief description of the study and the SurveyMonkey survey link. The data were collected over a 3-week period (April 5, 2011, to April 26, 2011).
Survey responses were collected from the SurveyMonkey database and analyzed using SPSS (Statistical Package for the Social Sciences, v19). Frequency analysis, percentages, and descriptive statistics were used to summarize the responses. Spearman's rho correlation coefficient (rs) was calculated for the relationship between respondent's interest level and each of the following variables: gender, age, SPRL, average weekly mileage, longest race distance completed in the past 6 months, and longest race distance planned to complete in the next 6 months. Chi-square test for independence (χ2) was calculated for determining the association between interest level and gender and interest level and history of running injury. The significance level for statistical testing was set at p ≤ 0. 05.
Descriptive characteristics of runners interested in and participating in barefoot or minimalist shod running were collected and correlated with independent variables. Influencing factors, used resources, perceived barriers, and expectations in runners who add barefoot or minimalist shod running to their training program were gathered and summarized. The findings to our knowledge are the first to describe the population of runners who are interested in or who participate in barefoot and minimalist shod running.
Two hundred and ninety-seven (37.8%) of survey respondents reported sustaining a running-related injury in the past 6 months. Of these 297, 293 reported the location of the injury, and 291 reported the time frame in which they were unable to run because of the injury. Specific injuries identified by survey respondents as “other” were classified into corresponding body categories. Most injuries reported involved the foot (24.2%, n = 71), the knee (21.5%, n = 63), and the lower leg (12.3%, n = 36). Three respondents indicated injuries at >1 site. The most prevalent time frame runners were unable to run was ≤2 weeks (44%, n = 128), followed by 2–4 weeks (21%, n = 61), 4–6 weeks (14.1%, n = 41), 6–8 weeks (8.9%, n = 26), ≥12 weeks (6.2%, n = 18), 10–12 weeks (3.4%, n = 10), and 8–10 weeks (2.4%, n = 7).
Participation and Intrerest Level
When asked about the current interest level in running barefoot or in minimalist shoes, 630 (80.2%) respondents that indicated they were at least somewhat interested (Figure 1). One hundred and seventy-two (21.9%) of the respondents had previously tried barefoot running, and 239 (30.4%) had previously tried running in minimalist shoes. The most commonly used minimalist shoes reported were the Vibram Five Finger (Vibram SpA, Albizzate, Italy), Nike Free (Nike, Inc., Beaverton, OR, USA), Saucony Kinvara (Saucony, Inc., Lexington, MA, USA), and New Balance Minimus (New Balance, Boston, MA, USA).
Implementation of Barefoot and Minimalist Shod Running
The primary motivating factor for those who had previously added barefoot or minimalist shod running (n = 283) to their training was prevention of future injury (n = 97, 34.3%). Other leading factors included performance enhancement (n = 59, 20.8%) and curiosity (n = 53, 18.7%). Of the respondents reporting the resources used in transitioning to barefoot or minimalist shod running (n = 277), advice from a running friend (n = 68, 24.5%) or from a book (n = 68, 24.5%) was most commonly reported. Born to Run by Christopher McDougall was the most frequently cited resource book. Other resources used included online resources (n = 67, 24.2%), journal articles (n = 21, 7.6%), or no resource at all (n = 21, 7.6%). Advice from a running coach or professional was the least used resource (n = 20, 7.2%).
Runners who had run either barefoot or in minimalist shoes (n = 272) most commonly transitioned to barefoot or to minimalist shod running over a period of 0–2 weeks (n = 96, 35.3%) and most commonly ran 0–5 miles per week (n = 117, 42.4%) barefoot or in minimalist shoes. The majority of runners who had tried running barefoot or in minimalist shoes did so as a supplement to training in regular running shoes (n = 120, 43.6%). Ninety-two (33.5%) reported replacing regular running shoes with barefoot or minimalist shod running, whereas only 16 (5.8%) reported replacing regular running shoes entirely by barefoot or minimalist shod running.
When asked about the most adverse reaction related to running barefoot or in minimalist shoes (n = 276), 116 (42%) reported no adverse reactions with the addition of barefoot or minimalist shod running. Of those reporting an adverse reaction, the most commonly cited condition was increased muscle soreness (n = 91, 33%), most specifically identified as located in the leg or foot. Of the runners who had tried barefoot or minimalist shod running, 222 (83.1%) reported no sidelining injuries since adding barefoot or minimalist shod running to their training.
Perceived Barriers and Preferred Resources
For all survey respondents (n = 785), the most prevalent perceived barrier in transitioning to barefoot or minimalist shod running was fear of possible injury (n = 424, 54.0%). Lack of adequate instruction (n = 184, 23.4%) and lack of adequate training surfaces (n = 140, 17.8%) followed. The least likely barrier identified was fear of decline in performance (n = 37, 4.7%). When questioned about which resource would be most helpful in transitioning to barefoot or minimalist shod running, survey respondents most frequently chose supervised instruction by a reputable coach or running professional (n = 208, 26.5%). Supervised instruction by a reputable coach or running professional was also chosen as the most helpful resource to motivate a runner to transition to barefoot or minimalist shod running was also (n = 334, 42.5%).
Survey respondents most frequently expected to use running barefoot or in minimalist shoes as an alternative training technique to supplement regular training (n = 282, 35.9%). Two hundred and fifty (31.8%) expected to improve performance, whereas 207 (26.4%) expected to prevent injury. Should survey respondents race barefoot or in minimalist shoes, the longest distance most would compete in is the 5K (n = 255, 28.7%). One hundred sixty-five (21.0%) indicated that they would not race barefoot or in minimalist shoes. An overwhelming 671 (85.5%) of survey respondents indicated that they were at least somewhat likely to continue with or to add barefoot or minimalist shod running if provided sufficient instruction (Figure 2).
Correlations with Interest Level
The relationship between respondent's interest level and each of the following variables was examined: age, SPRL, average weekly training mileage, longest race distance completed in the past 6 months, and longest race distance planned to complete in the next 6 months (longest future race distance planned to complete in the next 6 months) (Table 1). A weak negative correlation that was statistically significant was found between interest level and age (r s = −0.130, p < 0.05). This weak association between interest level and age suggests that younger runners tended to show greater interest in running barefoot or in minimalist shoes. A weak positive correlation that was statistically significant was found between interest level and SPRL (r s = 0.079, p < 0.05). This weak association indicates that self-described elite runners tended to show a greater interest in running barefoot or in minimalist shoes. A weak negative correlation that was not significant was found between the following variables: interest level and average weekly mileage (r s = −0.019, p > 0.05) and interest level and longest past race distance (r s = −0.057, p > 0.05). A weak positive correlation that was not statistically significant was found between interest level and longest future race distance (r s = 0.034, p > 0.05). Association between interest level and gender and interest level and history of running injury were also examined. A statistically significant relationship between interest level and gender was found (χ2 = 24.241, p < 0.05) with little effect size (Φ = 0.176) indicating that men were somewhat more likely to be interested in running barefoot or in minimalist shoes. However, no statistically significant relationship existed between interest level and history of running injury (χ2 = 5.897, p > 0.05) with little effect size (Φ = 0.087) (Table 2).
This is the first study to analyze interest level and participation in barefoot or minimalist shod running among runners and to examine demographics, motivating factors, used resources, perceived barriers and expectations in runners who add barefoot or minimalist shod running to their training program. Data indicate that runners who are men, of younger age, and who consider themselves elite runners are somewhat more likely to be interested in barefoot or minimalist shod running. Interest level and participation in barefoot or minimalist shod running are positively correlated. Surprisingly, no significant correlation between interest level and weekly mileage, injury history, or longest race distance was found.
Injury prevention (n = 97, 34.3%) was the most prevalent motivating factor for runners who previously added barefoot or minimalist shod running to their training program (n = 283). The barefoot running style may lead to less impact related injuries because of its midfoot to forefoot striking pattern that results in a shorter stride length and a higher stride frequency (11). These stride differences may possibly reduce initial impact forces by allowing higher preactivation of plantar flexors before braking at impact (6,10). Lower peak torques at the hip, knee, and ankle have been reported in barefoot vs. shod running, most prominently at the hip and knee (4). In this survey, injury to the hip and knee accounted for 31.4% (n = 92) of the injuries reported (n = 293). Ultimately, barefoot runners demonstrate decreased ground contact time, flight time, and stride duration because of the higher step rate (4,5,11,15). An increased step rate reduces step length, produces less vertical excursion of the center of mass, and reduces braking impulse and impact transient forces. In addition, an increased step rate by <10% does not alter metabolic costs and reduces impact load on the body because of the reduced vertical center of mass velocity at landing (8).
Increased proprioceptive feedback found in barefoot running may also contribute to prevention of injury. The sensory feedback from direct contact with the ground activates the intrinsic foot musculature, which allows for shock absorption and diminishes impact transmission (14). A well-trained foot disperses pressure to a wider area functionally avoiding injury. Barefoot running replaces the external, passive support of a shoe and with internal, active support by the foot musculature.
Despite the lack of research studies comparing injury rates in barefoot vs. shod populations, compelling biomechanical analysis may suggest its possibility. In developing countries where people are habitually barefooted, chronic injuries to bone and connective tissue are less common (14). Barefoot activity has been found to spare the plantar fascia from impact forces as the foot intrinsic muscles activate to control impact loads (14). In addition, where shod and unshod populations coexist, the injury rate is higher in the shod population (14). Unshod lifestyles are also associated with a lower frequency of lower extremity osteological modification (19).
Performance enhancement (n = 59, 20.8%) was the second most prevalent motivating factor for running barefoot or in minimalist shoes. Heart rate and relative perceived exertion have been found to be significantly higher in the shod condition (7). When running overground or on a treadmill, the recorded V[Combining Dot Above]O2 while running shod was 5.7 and 2.0% higher than when running barefoot (7). It has been found that at 70% of V[Combining Dot Above]O2max pace, barefoot running is more economical than is running shod, both overground and on a treadmill (7). Additional studies have found maximum oxygen uptake values to be 1.3% lower when running barefoot than when running in shoes (15). Despite these physiological findings, a >10% increase in step rate, which may be seen in barefoot running, has been associated with an increased relative perceived exertion and higher metabolic rates in runners (8). Running performance, therefore, may be adversely affected by the higher step rate during barefoot running despite the removal of the mass of the shoe.
Fear of possible injury was identified as the most prevalent perceived barrier to running barefoot or in minimalist shoes (n = 424, 54.0%). Despite the proposed advantages that barefoot running may present, there are several disadvantages a runner must consider when abandoning running shoe wear. The shoe functions to protect the plantar surface of the foot from harmful terrain and in extreme weather conditions. Additional features of the shoe allow for motion control, cushioning, stabilization, shock distribution, and traction between foot and the ground (2,6,10,12,16). Thus, going barefoot may result in increased puncture wounds to the foot and increased overuse of muscles, tendons, and ligaments providing stability for the foot. The additional cumulative loading that results from the increased step rate and forefoot striking pattern should also be considered as a potential source for injuries such as metatarsal stress fractures. Of the runners surveyed in our study who had tried running barefoot or in minimalist shoes, 116 (42%) reported no adverse reactions with the addition of barefoot or minimalist shod running. However, those reporting an adverse reaction cited increased muscle soreness (n = 91, 33.0%), most specifically identified as located in the lower leg or foot, as the most common adverse effect.
Although this survey included both running barefoot and running in minimalist shoes in the same category, it must be noted that the 2 are not the same. A shod runner may first opt to run in a minimalist shoe before making the full transition to barefoot running. A popular minimalist shoe studied in the literature is the Vibram FiveFinger (Vibram SpA, Albizzate, Italy). Research studies report that the minimalist shoe may offer some of the proposed benefits as running barefoot including similar forefoot striking pattern, lower ground contact time, higher step rates, and lower peak impact forces compared with the traditional running shoe (15). The minimalist shoe effectively mimics barefoot conditions while providing a small amount of protection; it, however, still sits between the foot and the ground and may desensitize and weaken the foot intrinsics (4,15). Nevertheless, the use of the minimalist shoe may prove to be useful in the overall transition to barefoot running.
Limitations in the survey design may have contributed to the data collected. Questions did not isolate barefoot running from minimalist shod running but were rather included together. Barefoot running is very different from running in minimalist shoes, and survey respondents may have answered questions reflecting on one aspect over the other. Furthermore, the term “minimalist shoe” was not specifically defined, so survey respondents may have answered questions based on their own definition of the term. Future surveys could separate running barefoot and running in minimalist shoes to obtain more definitive data on the 2 running conditions.
Additionally, the sample surveyed is small as a proportion of the population (13%) but relatively large in size (n = 785). This large sample size may have contributed to some statistically significant correlations; however, the strength of these findings was weak in nature. Additionally, the sample is geographically limited to central Florida, but it still provides an insight into runners' views of running barefoot or in minimalist shoes. Future research studies should aim to expand the sample geographically and attempt to gain a higher response rate.
Although these data only represent a small number of runners in the U.S.A. within a limited geographic area, they provide a clearer picture of runners' interest level, participation in, and implementation of running barefoot and in minimalist shoes. Community runners reported a considerable interest level in running barefoot or in minimalist shoes. Runners who are men, of younger age, and consider themselves elite are somewhat more likely to be interested in barefoot or minimalist shod running. Strength and conditioning professionals and coaches are likely to encounter runners who are interested in trying the barefoot style of running or running in minimalist shoes and who seek guidance in the transition process. The results of this study indicate that the preferred resource for guidance in the running transition was supervised instruction from a reputable coach or running professional, yet most runners use advice from friends or books to guide them. The results of this study also show that the primary motivating factor to run barefoot or in minimalist shoes was to prevent injury, yet fear of possible injury with this type of running is what retracted runners from doing so. For practical considerations, the coach can use the information discovered in this study to enhance the understanding of key factors related to barefoot and minimalist shod running and to aid in the supervision of a runner seeking to try these running techniques. Specifically, the coach should become informed about the biomechanics found in barefoot running and apply these differences in designing a transition program. The runner should then be closely supervised while paying special attention to injury prevention. Additional development and availability of evidence-based supervised transition programs will support the runner during the transition while minimizing adverse effects.
The author does not have any professional relationships with companies or manufacturers who will benefit from the results of this study. The results of this study do not constitute endorsement of the product by the author or the National Strength and Conditioning Association. The author received no financial support for this study. The author wishes to thank Jon and Betsy Hughes of the Track Shack, Orlando, FL, for their support of this study.
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Keywords:© 2012 National Strength and Conditioning Association
barefoot; shod; minimalist shoe