Drs Giuliani, Masini, Alitz, and Owens are from Keller Army Hospital, West Point, New York.
Drs Giuliani, Masini, Alitz, and Owens have no relevant financial relationships to disclose.
The views and opinions expressed in this article are those of the authors and do not reflect the official policy of the Department
of the Army, Department of Defense, or United States government.
Correspondence should be addressed to: Brett D. Owens, MD, Keller Army Hospital, 900 Washington Rd, West Point, NY 10996 (firstname.lastname@example.org).
Foot and ankle injuries associated with running, including stress-related changes and fractures, occur frequently. However,
causative factors, including anatomic and kinematic variables, are not well-defined.
Footwear choice also has been implicated in contributing to injury patterns with changes in force transmission and gait analyses
reported in the biomechanical literature. These studies also report conflicting data, particularly in the realm of the benefit
of the padded cushioned heel, which typifies modern high-performance distance running shoes.
Despite the benefits of footwear, interest in barefoot running has increased among the running community, with proposed benefits
including a decreased injury rate. Advocates tout the evolutionary success of man as a barefoot bipedal runner. There is also
speculation that the development of modern footwear and the associated altered running gait patterns (including a hindfoot
strike versus the forefoot or midfoot strike typical of unshod runners) have contributed to injuries seen in runners. However,
there is little prospective data to support these claims.
As a response to the rising popularity of barefoot running, several product lines of barefoot-simulating footwear have been
developed to allow the proposed benefits of barefoot running while providing protection to the sole from the environment and
giving the flexibility and natural feel of barefoot running. Runners with longstanding hindfoot striking gait patterns who
have transitioned to footwear developed for a forefoot or midfoot strike may be without specific training or practice in this
altered running pattern. This scenario represents a possible risk for repetitive stress injury to the foot or ankle as there
is a mismatch between the running style and the footwear design. This article presents 2 cases of experienced runners who
sustained metatarsal stress injuries as the result of running in barefoot-simulating footwear.
A 19-year-old man who ran 3 to 4 times weekly for an average of 20 to 30 miles per week presented with left foot pain and
dorsal swelling of 3 to 4 weeks’ duration. The onset of the pain correlated with new footwear (FiveFingers; Vibram, Concord,
Massachusetts) the patient was wearing while running.
The patient reported making no changes to his daily routine, mileage, or terrain. He noted pain with weight bearing, but he
continued with full weight bearing and had a mildly antalgic gait.
Physical examination revealed no obvious deformity of the left foot; hindfoot alignment and ankle range of motion were normal
with no evidence of tendo-Achilles tightness. Dorsomedial soft tissue swelling was noted over the second and third metatarsal
shafts. There was no ecchymosis or crepitus; however, the patient had significant tenderness to palpation at the dorsal and
plantar aspect of the second metatarsal.
Radiographs of the left foot demonstrated no signs of fracture or dislocation. Magnetic resonance imaging (MRI) was consistent
with stress reaction of the entire second metatarsal with adjacent soft tissue edema (Figure ).
Figure 1:. T1-weighted axial fat-suppressed MRI of the left foot is consistent with stress reaction changes of the second metatarsal.
The patient was treated with crutch-assisted weight bearing until he no longer ambulated with an antalgic gait. He then was
advised to avoid impact aerobics for an additional 8 to 10 weeks and to modify his activity to low-impact aerobic exercise.
A 35-year-old ultra-marathon runner who ran 3 to 4 times weekly for an average of 30 to 40 miles per week presented to the
emergency department with sudden-onset left foot pain after running 3 miles. The patient reported making no changes to his
training mileage, frequency, or terrain. The only recent change to his training was the incorporation of new footwear (FiveFingers)
approximately 6 weeks prior to injury.
The pain was associated with difficulty ambulating, and radiographs were interpreted as negative for fracture at that time.
The patient was instructed to stop running and was referred to the orthopedic clinic for follow-up.
On presentation to the orthopedic clinic 1 month later, the patient was weight bearing with normal footwear and had a mild
antalgic gait. Physical examination revealed no obvious deformity of the left foot; hindfoot alignment and ankle range of
motion were normal with no evidence of tendo-Achilles tightness. Dorsal soft tissue swelling of the foot was noted. There
was no ecchymosis in the area or crepitus to palpation; however, the patient had significant tenderness to palpation over
the dorsal and plantar aspect of the second metatarsal shaft.
A repeat radiograph obtained at the clinic demonstrated a periosteal reaction and callus formation of the second metatarsal
diaphysis, although no fracture lucency was visualized (Figure ). T2-weighted MRI of the foot demonstrated increased signal within the second metatarsal shaft consistent with stress fracture
(Figure ). The patient was instructed to avoid impact aerobics for an additional 6 weeks and to modify his activity to low-impact
Figure 2:. AP radiograph of the left foot 1 month after injury shows evidence of a healing second metatarsal diaphysis stress fracture.
Figure 3:. T2-weighted sagittal fat-suppressed MRI shows increased signal and cortical thickening consistent with stress fracture of
the second metatarsal.
The transition to cushioned-heel running footwear is a relatively recent phenomenon, with the advent of the modern running
shoe only dating to the 1970s.
Barefoot running is a modality that by anatomic study dates to early man, and the characteristic gait of native unshod runners
has borne the test of time as a successful means of locomotion.
The resurgence in popularity of barefoot running as an alternative to the wearing of modern footwear has been based in part
on the theory that there is reduced risk of injury; however, there is an absence of data supporting this.
The need for cushioned soles has been questioned with the launch of several product lines of footwear that simulate barefoot
running while offering some protection to runners’ feet. Among these is the shoe that was worn by both patients in this case
series. The purpose of this footwear is to facilitate the barefoot running experience while protecting the foot from modern-day
elements such as pavement, broken glass, or other hazards that would be directly injurious.
Although the superiority of one footwear style over another is outside the scope of this article, it is relevant to discuss
the possibility that there is an association with the transition from modern cushioned-heel footwear to barefoot-simulating
footwear with the metatarsal stress injuries described in these 2 cases. Stress injuries to the metatarsals are common in
the recreational running population and may be associated with changes in a training routine such as distance, intensity,
Stress fractures in the foot are also common in military populations. March fracture is the name given to stress fractures
of the second and third metatarsals commonly seen in military recruits after long marches. The second and third metatarsals
are rigid while marching and are common sites of injury. The majority (75%) of march fractures occur in the distal or middle
one-third of the metatarsal shaft.
The location of the fractures in our 2 cases was more proximal in the metatarsal shaft than the typical march fracture. Our
patients had long-standing running routines prior to presenting with a metatarsal stress fracture in a location not commonly
seen in overuse metatarsal stress fractures. For these 2 runners, a common factor appears to be the transition from a cushioned-heel
modern running shoe to barefoot-simulating footwear.
The kinematics and biomechanics of shod and barefoot runners has been described in the literature. One notable difference
between the 2 styles is the foot-strike pattern typical of each. In a landmark study, Lieberman et al
reported on these differences in a comparison of shod and unshod runners that included an evaluation of runners from the
Rift Valley region of Africa who have never worn shoes. Runners who regularly wear or who have grown up wearing cushioned-heel
footwear primarily have a hindfoot strike gait pattern. Lieberman et al
found that this strike persisted when these same runners were tested in an unshod condition. In runners who grew up barefoot
running or who have transitioned to barefoot running, a forefoot or midfoot strike predominates.
Both of our patients grew up and typically trained wearing cushioned-heel footwear. They can be presumed to have a hindfoot
strike typical of this general running population.
They also likely continued running with a hindfoot strike as they transitioned to barefoot-simulating footwear consistent
with the findings of Lieberman et al.
The advantage of the forefoot strike gait in barefoot running is a flatter foot position at impact, which limits the local
pressures underneath the heel. Barefoot runners typically adopt a gait pattern with shorter stride length and increased stride
frequency. These adaptations facilitate the altered touchdown foot position.
They also serve to decrease the vertical forces transmitted to the limb, which may have further implications in injury prevention.
An additional advantage is gained with the finding of decreased energy expenditure in barefoot versus shod running.
In another study evaluating adaptations of stride mechanics in shod and unshod running trials on a treadmill, no in-trial
limb position adaptations were noted in barefoot trials whereas shod runners made multiple adjustments in running mechanics
during the course of the trial.
The authors postulated that this may be due to a natural state of barefoot running that needs no alteration to find the biomechanically
efficient gait pattern. However, this also seems to be a risk factor predisposing a runner to repetitive stress injury.
With a transition to barefoot running from cushioned-heel footwear, Lieberman et al
described a persistence of a hindfoot strike gait. If a runner of this type does not make gait adaptations, as described
by Divert et al,
there is potential for perpetuation of a gait that does not provide the efficiency and force reduction expected with barefoot
running. An overuse stress injury is the predictable result and may be what was experienced by our 2 patients.
This article presents 2 runners who transitioned from a modern cushioned-heel running shoe to a barefoot-simulating shoe without
alteration to their running routine or any specific gait training. Both runners developed a stress injury to their second
metatarsal shaft. We propose that the alteration from a cushioned-heel shoe to barefoot-simulating footwear without specific
gait training may have contributed to their injuries.
- 1. Harrast MA, Colonno D. Stress fractures in runners.
Clin Sports Med. 2010; 29(3):399–416. doi: 10.1016/j.csm.2010.03.001
- 2. Bishop M, Fiolkowski P, Conrad B, Brunt D, Horodyski M. Athletic footwear, leg stiffness, and running kinematics.
J Athl Train. 2006; 41(4):387–392.
- 3. Butler RJ, Davis IS, Hamill J. Interaction of arch type and footwear on running mechanics.
Am J Sports Med. 2006; 34(12):1998–2005. doi: 10.1177/0363546506290401
- 4. Hardin EC, van den Bogert AJ, Hamill J. Kinematic adaptations during running: effects of footwear, surface, and duration.
Med Sci Sports Exerc. 2004; 36(5):838–844. doi: 10.1249/01.MSS.0000126605.65966.40
- 5. Kong PW, Candelaria NG, Smith DR. Running in new and worn shoes: a comparison of three types of cushioning footwear.
Br J Sports Med. 2009; 43(10):745–749. doi: 10.1136/bjsm.2008.047761
- 6. Squadrone R, Gallozzi C. Biomechanical and physiological comparison of barefoot and two shod conditions in experienced barefoot runners.
J Sports Med Phys Fitness. 2009; 49(1):6–13.
- 7. Lieberman DE, Venkadesan M, Werbel WA, et al. Foot strike patterns and collision forces in habitually barefoot versus shod runners.
Nature. 2010; 463(7280):531–535. doi: 10.1038/nature08723
- 8. Bramble DM, Lieberman DE. Endurance running and the evolution of
Nature. 2004; 432(7015):345–352. doi: 10.1038/nature03052
- 9. Bernstein A, Childers MA, et al. March fractures of the foot: care and management of 692 patients.
Am J Surg. 1946; 71:355–362. doi: 10.1016/0002-9610(46)90275-9
- 10. Hasegawa H, Yamauchi T, Kraemer WJ. Foot strike patterns of runners at the 15-km point during an elite-level half marathon.
J Strength Cond Res. 2007; 21(3):888–893.
- 11. De Wit B, De Clercq D, Aerts P. Biomechanical analysis of the stance phase during barefoot and shod running.
J Biomech. 2000; 33(3):269–278. doi: 10.1016/S0021-9290(99)00192-X
- 12. Divert C, Mornieux G, Baur H, Mayer F, Belli A. Mechanical comparison of barefoot and shod running.
Int J Sports Med. 2005; 26(7):593–598. doi: 10.1055/s-2004-821327
- 13. Divert C, Baur H, Mornieux G, Mayer F, Belli A. Stiffness adaptations in shod running.
J Appl Biomech. 2005; 21(4):311–321.
- 14. Burkett LN, Kohrt WM, Buchbinder R. Effects of shoes and foot orthotics on VO2 and selected frontal plane knee kinematics.
Med Sci Sports Exerc. 1985; 17(1):158–163.