ABSTRACT
The popularity of the barefoot movement in sports and fitness activities has soared within the past few years as evidenced by a growing community of minimalist footwear enthusiasts wearing the ‘glove’ shoes in their sporting endeavors, fitness workouts, and everyday leisure activities. This emergence of the minimalist shoes, such as the Nike Free© and Vibram FiveFingers®, has created a wave of intrigue for those sport and fitness enthusiasts wanting a natural running experience without being subjected to the hazards of the road. Whether running barefoot, in shoes or in minimal footwear, the trends in footwear preference have caused much debate between researchers as to which form causes more injuries and/or best serves to enhance athletic performance. As sport and fitness professionals, it is important to thoroughly examine the current footwear trends to develop a ‘best practices’ approach for advising our athletes and clients.
INTRODUCTION
Running has been a natural form of transportation since the beginning of time when our ancestors ran in order to hunt and gather food to survive. Since shoes did not exist at the time, people engaged in everyday activities barefoot. The evolution of the shoe has changed dramatically over time, from animal skin moccasins to leather dress-wear to rawhide boots; yet a shoe dedicated to athletic endeavors is a relatively recent phenomenon. Introduced in the 1960’s, the rudimentary running shoe (canvas and leather) provided athletes with a footwear option that is better suited for sporting events (10, 4). Since the latter part of the twentieth century, the public has been wearing running shoes everywhere: they train, compete, and wear their running shoes as everyday leisure and fitness wear.
Although the running shoe has become a way for people to express their style, many runners are converting back to barefoot running or minimalist footwear
such as the Nike Free© and Vibram FiveFingers shoes®. Fitness enthusiasts are participating in barefoot warm-ups and cool-downs in hopes of enhancing
their performance on the court, field, and track.
The trends in footwear preference has caused much debate among researchers as to which form causes more injuries. Researchers have observed humans running
barefoot, in shoes and/or in minimal footwear while on various running surfaces. The occurrence of injuries seemed to rely on the product, running experience,
and environment. Each study has found many pros and cons to running shod and non-traditionally. To understand shod running and non-traditional running, characteristics
need to be identified for both. Shod running is running in the modern running shoe and non-traditional running includes barefoot or the wearing of minimalist
footwear. This paper will discuss the history of running, non-traditional running, injuries related to running, and practical applications for the sport and fitness
professional.
History of Running
When did humans begin to run? This question has been intriguing researchers for years. Bramble and Lieberman (4) indicated, “the fossil evidence of
these features suggests that endurance running is a derived capability of the genus, Homo, originating about 2 million years ago, and may have been instrumental
in the evolution of the human body form” (p. 345). The physiological features of the human form included stride length, spring-like tendons, thermoregulation,
respiration, and the ability to run for long periods of time over great distances (10, 4). Unlike many animals that can run at high speeds for several minutes,
humans have the capability to run at slower speeds for long distances. In fact, humans have been identified as the only primates capable of endurance running
(10).
How People Ran Without Running Shoes
Our ancestors ran barefoot and did so for long periods of time. The evolution from walking to running, a locomotor skill that man developed in an effort to
more efficiently and effectively hunt their food, provided evidence that the human body was designed to run for long distances (4, 10). Daniel Lieberman
(10) studied populations of runners in Kenya and the United States to determine the difference in running gaits between three groups; “those who had always
run barefoot, those who had always worn shoes, and those who had converted to barefoot running from shod running” ( p. 1). The study concluded that
barefoot runners strike the ground on the middle of their foot first and shod runners hit the ground heel first. Hitting the ground heel first produced injuries
on the lower extremities of the body, including the ankles, knees, and hips. Less impact was generated in mid-foot striking because this part of the foot
naturally has more cushioning. Runners in traditional shoes “experience a very large and sudden collision force about 1,000 times per mile run ….
barefoot [runners], however, tend to land with a springy step towards the middle or front of the foot” (10, p. 1).
Olympic athletes have also performed barefoot; runners such as Abele Bikila and Zola Budd were the two most famous barefoot runners. Bikila set a new world
record time of 2:15:16 in the marathon at the 1960 Olympic Games while running barefoot. Zola Budd, another barefoot runner, twice broke the world record in
the women’s 5000m event (14). Although these runners were exceptional examples of the effects barefoot running could have on human athletic performance;
the fact is, the majority of the sporting world wears shoes. This begs the question: what are the design mechanics of running shoes that make them so different from
exercising barefoot?
Invention and Mechanics behind the Traditional Running Shoe
The Nike, Inc. (Nike) company is credited with inventing the running shoe as we know it today. Unlike other athletic shoes of the time period, the Nike shoe
was thought to be far superior due to its advanced motion control, heel cushioning, and shock absorption (17). Yet, as reported by Tweeney (17) “strong evidence
shows that thickly cushioned running shoes have done nothing to prevent injury in the 30-odd years since Bill Bowerman invented them” (p. 2).
Dr. Stephen Pribut, a renowned physician who specializes in Podiatric Sports Medicine, discussed the importance of knowing which type of shoe is appropriate
for each individual sport, as he acknowledged that the development of the traditional running shoe may have led to increased injuries in runners (16). In a 2010 Harvard
study (10), more than 75 percent of American runners who wore traditional shoes were likely to strike heel first. According to Pribut (16), “the purpose
of an athletic shoe is to protect the foot from the stresses of your sport, while permitting the athlete to achieve his maximum potential” (p. 1).
A shoe is made up of the midsole, outer heel, inner heel, fore-foot, and heel counter. These parts of an athletic shoe are designed to make running more comfortable
and safe. Yet, injuries can occur due to the basic design mechanics of the shoe; specifically, Achilles tendonitis has been known to occur in people who wear
shoes made with hard stiff soles (12, 16, 8, 10), which may lead to increased injuries in the runner.
Wearing shoes that have outlasted their life span can increase the chances of injury as well. The midsole is designed to absorb shock and loses its capacity
to do so as mileage increases. For example, a runner who routinely logs (or completes) 20 miles a week should change their shoes by week 20-25 because the
life of a shoe is typically made to withstand 350-550 miles (16). The sole of a shoe does not factor into the amount of shock absorption (16), so runners
are advised to adhere to the 350-550 mileage rule. Length and width are also important. It is recommended to have at least one finger width at the toe of
the shoe and the ‘widest past of the shoe should be at the widest part of your foot’ (16, p. 3). Tying a shoe too tightly could create sharp
pain, or even numbness, in the foot. Running with a loose shoe could create too much movement within the box of the shoe.
The design mechanics, as well as the type of shoe, can affect the overall performance of the athlete. Dr. Pribut described the differences between tennis players
who perform repeated lateral movements as compared to walkers and runners who move forward in a straight line. Racquet sports, such as tennis, badminton,
and racquetball, require a lateral motion in which the side-to-side stability of the foot must be provided by a firm shoe design (16). Having an unstable
shoe for a sport which relies primarily on lateral movement could result in greater injury to the athlete. Pribut also stated the importance of purchasing
sport-specific shoes. Knowledge of the footwork requirements of the particular activity should determine the type of shoe that is worn by the athlete (16).
Non-Traditional Running
Shoes or no shoes? For centuries, runners have been running barefoot; however, non-traditional running has made a splash in the running world. Athletes as
well as fitness enthusiasts have embraced the concept of minimal footwear by purchasing shoes like the Nike Free© and Vibram FiveFingers®. These
minimalist shoes give the feeling of running barefoot but with the added protection of a sole. A popular shoe retailer, Barefoot Running Shoes, touted
that the Nike Free© strengthens the lower body and feet by imitating barefoot movement (1). The same retailer also advertised the Vibram FiveFingers®
as a shoe which gives the runner the ability to experience the sensation and freedom of going barefoot with the added protection to endure in the ‘modern
environment’ (2). The question arises as to whether these types of minimalist footwear have actually reduced the number of injuries seen in runners.
Mechanics of Barefoot Running
As compared to traditional shod running, barefoot running has appeared to have more advantages, as related to health concerns and decreased injury rates. In
2004, Divert et al. (7) investigated shod versus barefoot running by examining 35 subjects while running on a treadmill for a specific period of time and speed.
The study called for 31 male and 4 female runners with leisure training experience and no injuries. Two test sessions were administered. The first session required
the subjects to run on the treadmill to become more familiar with running on the treadmill. The second session required the subjects to complete two running
periods (one shod and one barefoot) each for four minutes. The researchers used a Treadmill Dynamometer and an Electromyography (EMG) to record the results
of each participant. The EMG measured the Medial Tibialis, Medial Peroneus, Medial Gastrocnemius lateralis, Medial Gastrocnemius medialis and Medial Soleus.
The results revealed lower numbers for barefoot running in contact time, flight time, passive peak, and stride duration. The parameters measured each person
running around 60 consecutive steps. Divert et al. (7) concluded that “barefoot running leads to a reduction of impact peak in order to reduce the high mechanical
stress occurring during repetitive steps. This neural-mechanical adaptation could also enhance the storage and restitution of elastic energy at the ankle
extensors” (p. 593). Thus, the barefoot runners appeared to have a decreased chance for injury.
What Do the Nike Free© and Vibram FiveFingers® Shoes Offer?
The Nike Free© and Vibram FiveFingers® shoes are the newest invention in the world of minimalist footwear. Although running purely barefoot can increase
a person’s risk of injury by contacting foreign objects on the road or rail, minimalist footwear offers the sensation of running barefoot while protecting
the sole of the foot.
According to Wilk et al. (19) the “Nike Free© allows the feet to move through their natural range of motion which creates the feeling and effects
of running barefoot” (p. 17). Running while wearing the minimalist shoe has generated increased media attention. The researchers (19) tested runners
on a treadmill using video-gait analysis to determine if the Nike Free© running shoe allowed the foot to move naturally striking mid-foot versus heel
first. The researchers chose to use the Nike Free© rather than having the participants run purely barefoot because of the safety issues involved when
testing on a treadmill. Due to the fact that the foot, ankle, leg, and body experience a great deal of force when running, the objective was to discover
possible corrective measures to the subtalar misalignment, which often leads to injuries. The Nike Free© allowed the researchers to identify “overpronation,
supination, and other gait abnormalities” characteristic of subtalar conditions. Wilk et al. (19) concluded that the, “Nike Free©, when used with
video-gait analysis, allows for proper assessment of running biomechanical abnormalities that contribute to injury” (p. 17).
The Vibram FiveFingers® is another popular type of minimalist footwear that provides the feel of running barefoot without the constricting nature of a traditional
running shoe. This minimalist shoe fits like a glove on the foot. Author and barefoot runner, Chris McDougall (13), claimed that his problem with plantar
fasciitis was healed when he began running in the Vibram FiveFingers®. According to Tony Post, president and CEO of Vibram USA, the Vibram FiveFingers® allow
the foot to absorb shock and flex (2). In traditional running shoes, the runner’s stride lengthens and the foot strikes the ground in a heel first fashion. Tweeney
(17) concluded that runners could avoid injury by running barefoot or by wearing minimalist footwear; it was simply a matter of going ‘back to the basics’.
The Nike Free© and Vibram FiveFingers® shoes both offer the characteristics and design mechanics of barefoot running with the added benefit of protecting
the foot from the hazards of the road.
Injuries Related to Running
Running has steadily increased in popularity in the United States with more than 30 million sport and fitness enthusiastic participating annually
(9). Although running has been proven to improve cardiovascular health, lower leg injuries have become more and more prevalent in runners today. Some researchers
(12, 19, 16) believe the injuries may be due in part to the structure of the running shoes.
Shod Running Injuries
The modern running shoe has been designed to have more cushioning and shock absorption to prevent the force of shock waves sent up the body when the foot
strikes the ground. According to Lieberman et al. (12), the heel-toe running pattern has led to lower extremity injuries such as plantar fasciitis, Achilles
tendonitis, and knee and hip injuries. A traditional shoe limits the proprioceptive abilities and ankle motion of the foot, as well as decreases the opportunity
to strengthen the muscles of the feet. The stiff soles of the traditional running shoes have led to weaker foot muscles and reduced arch strength (12, 16, 8,
10).
Shoes have been called the “perceptual illusion” (5) to running because they limit the feet from feeling the surface and striking the ground
in a natural movement. Researchers from The Journal of Injury, Function and Rehabilitation (8) performed a study on 68 young adult runners, 37
of them being women. All the runners ran in typical modern running shoes, had no history of musculoskeletal injuries, and ran 15 miles per week. Each runner
was monitored on a treadmill running with shoes and then running barefoot. After data was collected, the researchers discovered that the runners had increased
joint torques at the knee, hip and ankle joints compared to running barefoot.
According to the research cited thus far, traditional running shoes have been found to increase the rate of injury in runners; however, perhaps the price
of a running shoe makes a marked difference in injury rates. Walker and Blair(18) found a 123% increase in injury frequency with expensive shoes over less
expensive shoes. Similarly, another group of researchers (3) conducted a study using nine adults (six men and three women) who were injury free for at least
six months, physically fit, and were accustomed to running on treadmills. The objective was to find the affects of leg stiffness when wearing athletic shoes.
The shoes chosen for the experiment were “athletic joggers” costing $10 (low cost) and “light weight cushioned trainers” costing $65
(high cost). The results concluded that cushioned running shoes increase limb stiffness compared to running barefoot. Ultimately, Bishop et al. (3) found
that “footwear influences the maintenance of stiffness in the lower extremity during hopping and joint excursion at the ankle in running” (p. 387).
Preventing Running Injuries Through Barefoot Activity
Every year runners around the world are diagnosed with high number of injuries (9). This prevalence has brought researchers together to evaluate why the injury
rates have increased. Although there is limited research to indicate that runners and other fitness enthusiasts are less injury-prone when wearing running shoes
(6), barefoot or minimalist running is not something to just dive into without first testing the proverbial waters. The muscles are not adapted or strong enough
yet to take on the degree of strength it takes to run barefoot. Tweeney (17) warned that people should be aware that exercising while barefoot or wearing
minimalist shoes should involve a slow transition. It is recommended that those who are not accustomed to barefoot activity begin in their home and then move
outside to grass until the muscles have built enough strength and tolerance. Other options for barefoot activity include: yoga, Pilates, and group fitness
classes. The concept of going purely barefoot has not won over many podiatrists who, according to Parker-Pope (15) “cringe at the notion of unshod feet
pounding the pavement, where the risks include cuts, bruises, and unsanitary conditions” (p.1). However, proponents say barefoot training helps correct
form and reduces foot, shin, and muscle injuries (15); thus, leading to fewer injuries to the runners. Many doctors, coaches, podiatrists, and physical therapists
agree that people spend too much time in shoes (15, 14, 16) and support the idea of walking around the house, strength training, and/or running barefoot
a few times a week on a safe surface preferably in minimal footwear, such as the Nike Free© and Vibram FiveFingers® shoes.
APPLICATION IN SPORT & FITNESS
Fad or New Fitness Standard
Although many professionals believe barefoot or minimalist shoes decrease the amount of injuries and increase performance, there are still those people who
believe this is a fad that will fade out in time. Fad or not, the Nike Free© and Vibram FiveFingers® can be seen on feet just about everywhere, from
college campuses and exclusive fitness centers to road races and hiking trails. Interestingly, the Vibram company, which introduced the FiveFingers® minimalist
shoe in 2006, has experienced tripled sales growth (6) each year since the minimalist footwear trend began.
Issues within the Sport & Fitness Industry
The minimalist shoes, Nike Free© and Vibram FiveFingers®, are growing in popularity in the sport and fitness world. Many athletic weight rooms
as well as fitness and recreation centers at colleges and universities are permitting the use of these shoes in their facilities. The versatility of these shoes allows
the individual to exercise in many areas, including the weight room, cardiovascular machines, group exercise classes, basketball courts, and even the rock climbing
wall. Yet, some athletic performance coaches and facility managers are strict traditionalist and insist that all patrons wear closed-toe athletic shoes, which
translates to the traditional athletic shoes rather than the minimalist footwear. Perhaps professional conferences or workshops should host sessions which address
the validity of the minimalist shoe as an approved alternative to traditional dress code policies within weight rooms and fitness centers.
The Learning Curve: How to Adjust Your Workouts
Many track and cross country coaches have long endorsed the use of minimalist shoes or even barefoot training in the running world. Barefoot activity, including
minimalist shoes, has been proposed as a prevention strategy to help prevent running injuries. Barefoot activity does not necessarily mean running barefoot,
but rather performing various activities barefoot for a period of time each day. These activities range from walking on a smooth trail to running on the
grassy infield of a track. For example, many track and cross country coaches recommend that athletes (sprinters and distance runners) perform their cool-downs
barefoot on the grass of the track infield. If these activities are performed for at least one hour each day, it can lead to increased arch height and muscle
strength. Hart and Smith (2008) reported that the activities performed when barefoot created an arch pattern that ‘mimics the typical arch observed
in barefoot populations’, which have typically reported a very low incidence of running injuries (9).
Although many fitness professionals have endorsed the barefoot or minimalist shoe movement, Krauss (2011) cautioned that those in the fitness industry should
proceed with ‘proper progression’ as a component of conditioning the feet and lower legs (11). Shanna Moody, Tarleton State University Fitness/Wellness
Coordinator, is a big proponent of going barefoot and/or wearing the Nike Free© or Vibram FiveFingers® shoes. Shanna’s philosophy as a fitness/wellness
professional goes back to the functional aspects of exercise, “taking off your shoes and strengthening from the feet up is where I think people should
begin.” As described by Ms. Moody, many clients can directly relate their pains and injuries back to the type of shoe they are wearing.
CONCLUSION
The information found on shod running and non-traditional forms of running proves to be very informative in regards to the history, benefits, controversies, and
developing interest in the sports and fitness realm. While the advantages of true barefoot running or exercise have been thoroughly documented in the literature,
it does not seem to be an ideal training concept for those in the sports and fitness industry as it relates to hygiene and safety issues. However, the increased popularity
of minimalist footwear, which has grabbed the attention of researchers as well as runners and recreational athletes, may be a legitimate alternative to the barefoot
movement. The emergence of the minimalist shoe has created a wave of intrigue for those fitness enthusiasts wanting a ‘natural’ exercise experience,
while maintaining personal hygiene in the gym. The minimalist footwear also allows runners to ‘feel’ the foot strikes and reap the physiological benefits
of running sans traditional shoe without being subjected to the potential hazards of the road. The Nike Free© and Vibram FiveFingers® shoes have also become
popular with those interested in the latest fashion trends. Many individuals are simply wearing the minimalist footwear because it has evolved as this generation’s
version of the flip-flop.
As sport and fitness professionals, it is important to thoroughly examine the various trends that may impact our athletes and clients. Are the Nike Free©
and Vibram FiveFingers® shoes simply a passing fashion fad or a fitness footwear trend that will be here for the long run? Historically speaking, humans began
running and living barefoot . . . it will be interesting to see if minimalist shoes will be a part of the human lifestyle in the future.
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