References
Underpronators & Plantar Fasciitis
Discussion Introduction
Biomechanics & Gait
Overpronators & Plantar Fasciitis
Benefits of Barefoot Running
Commentary: Barefoot running as a possible management strategy for Chronic Plantar Fasciitis
John Stacey
Institute of Physical Therapy & Applied Sciences
This commentary will review the biomechanical causative factors of plantar
fasciitis and aims to identify the potential mechanisms involved in barefoot
running which would assist in the rehabilitation of chronic plantar fasciitis
Plantar fasciitis is a commonly encountered problem in the physical therapy
clinic, with Singh et al. (1997) describing it as the most common cause of heel
pain presenting to the outpatient clinic. Despite this prevalence, little scientific
evidence exists concerning the most appropriate intervention. Often thought of
as an inflammatory process, plantar fasciitis is an overload disorder of
degenerative changes in the fascia (Lemont et al. 2003).
Bolga & Malone (2004) describe plantar fasciitis abnormalities in terms of
overpronation and underpronation, to help the clinician in their decision
making process for its evaluation and treatment.
Krabak (2011) argues for the inclusion of barefoot running as a cross training
tool in lower extremity injury as the human has spent more time running
barefoot than shod in the evolutionary cycle, leaving us ‘designed to
endurance-run barefoot’. He describes the advantages of barefoot vs shod
running to include less impact forces and resultant joint torques to the lower
extremity, a greater conversion of energy to rotational energy, a greater
efficiency and possible improvement in foot intrinsic muscle strength.
Chronic fasciitis can be a debilitating and frustrating injury to the competitive
athlete, resulting in interference with and absence from training. Athletes often
seek out any This author has observed the use of barefoot running as a
treatment strategy of chronic plantar fasciitis in two competitive athletes
attending his clinic. This has led the author to question the proposed benefit of
barefoot running on chronic plantar fasciitis and to identify the potential
mechanisms involved. This poster will briefly review (1) the mechanisms
involved in plantar fasciitis, (2) the mechanics and current rationale for the use
of barefoot running and (3) the potential use of the latter as a treatment strategy
for chronic plantar fasciitis pain in athletes.
travelling upward on the calcaneus and the metatarsal heads, result in this
flattening effect. However just as the plantar fascia absorbs tensile stress in the
first half of the stance phase, tightening of the fascia is required to provide a
solid structural support, during the second half of the stance phase. This
structural tension provides a rigid lever arm to propel the body forward from
toe off.
Bolga et al. (2004) identify a need for an efficient balance between pronation
and supination, with too much or too little of either at the wrong time of the
gait cycle, leading to potential dysfunction of the fascia. However they note
that excessive foot motion e.g. overpronation in itself, is not a deterministic
factor of lower extremity problems; rather continuous functioning beyond
normal end range motion (EROM) or spending longer durations beyond
normal EROM.
Prolonged foot pronation leading to plantar dysfunction occurs through three
mechanisms (Bolga et al., 2004).
(1) Muscle weakness: Repeated pronation beyond EROM may result in
inhibition of the tibialis posterior, one of the most significant dynamic arch
stabilisers during stance. Proximally, weakness in gluteus medias, minimus
and TFL will reduce proximal shock absorption and decrease proximal
pronation control.
(2) Heel chord tightness: Lack of ankle dorsiflexion, will often be compensated
by unlocking the midtarsal joint during the midstance phase. This increased
motion results in excessive pronation which can stress the plantar fascia.
(3) Structural deformities: Excessive subtalar or forefoot varus deformities
require excessive pronation to allow the medial metatarsal heads to weight-
bear.
Athletes who underpronate, or those with a rigid high arch are just as likely to
present with plantar pain, due to the foots reduced ability to dissipate force.
This foot type, often presenting with limited joint mobility, places the fascia
under continuous tension leading to adaptive tissue shortening and decreased
plantar fascia extensibility.
The reduced mobility and decreased shock absorption also results in increased
tensile stress at the plantar fascia insertion, a common pain source. A cavus
foot will also lead to increased tightness in the gastrocnemius, soleus and
Achilles tendon (Bolgla & Malone, 2004).
Most shod athletes exhibit a rearfoot strike pattern compared with the mid-
foot or more typically forefoot strike pattern of the barefoot athlete (Fig 2).
Lieberman et al. (2010) demonstrate the advantages of this forefoot strike
pattern, which shows a lower rate of loading and greater conversion of energy
to rotational energy vs a rearfoot strike pattern. Shod athletes were also
shown to have greater collision forces (x1.5-3 times body weight) or impact
transients with heel strike (Fig 2). These impact transients are sudden forces
with high rates and magnitudes of loading that travel rapidly up through the
body.
The same researchers suggest that these forces may contribute to the high
incidence of running related injuries, including plantar fasciitis. Krabak et al.
(2011) also reports on greater efficiency in the barefoot runner through
decreased torques in the hip and knee, as well as a proposed improvement in
foot intrinsic muscle strength.
Figure 2: A comparison of vertical ground reaction forces and foot
kinematics for shod and barefoot athletes. The impact transient is
noted in the shod athlete’s GRF. Adapted from Lieberman et al. (2010)
It is important to remember as a clinician that the etiology of injuries is
multifactorial and barefoot running may be one component of a comprehensive
rehabilitation plan. From the brief review of the literature above, two possible
explanations for the inclusion of barefoot running as a modality in addressing
the causative factors in plantar fasciitis are apparent.
Firstly, forefoot mechanics associated with barefoot running tend to load the
medial arch from a distal to proximal direction and spread this loading from the
point of initial contact through to the end of the midstance phase (vs the
opposite direction and over a shorter time period in shod running). This more
gradual and lower force loading of the medial arch will decrease the intensity
and rate of stretch to the dynamic arch stabilisers e.g. tibialis posterior. As the
average runner typically strikes the ground 600 times per kilometre, barefoot
running decreases the likelihood of overuse and reduced capacity in these arch
stabilisers.
Along with the lower rate of loading the absence of impact transients with heel
strike during barefoot running further decreases stress to the already painful
fasciitis. This suggests that it would be an ideal alternative to shod running in
the rehabilitative programme for both over- and underpronators, with less
aggravation of symptoms.
The literature above looks at experienced barefoot athletes and does not take
into account the many training and clinical issues that would arise when
introducing barefoot running to the athlete for the first time. A gradual and
continuously reviewed programme would be highly recommended, allowing
the body to adapt to this new mode of running. This may suggest that the
effectiveness of barefoot running as a treatment strategy may be limited to
those athletes with chronic plantar fasciitis, as shorter lived pathologies may
not have enough time to reap potential benefits.
In theory, barefoot running offers significant biomechanical advantages to shod
running, some of which may decrease the causative factors in plantar fasciitis.
However controlled clinical trials are required to investigate the effect and best
practices in using barefoot running as a treatment modality for plantar fasciitis.
• Krabak, B.J., Hoffman, M.D., Millet, G.Y. (2011) Barefoot Running. PM&R. 3(12):1142-
1149.
• Lieberman, D.E., Venkadesan, M., Werbel, W.A., Daoud, A.I., D’Andrea, S., Davis, I.S.,
Mang’Eni, R.O., Pitsiladis, Y. (2010) Foot strike patterns and collusion forces in habitually
barefoot versus shod runners. Nature. 463(28):531-536.
• Bolga, L.A. & Malone, T.R. (2004) Plantar Fascitis and The Windlass Mechanism: A
Biomechanical Link to Clinical Practice. Journal of Athletic Training. 39(1):77-82.
• Lemont H., Ammirati, K.M. & Usen N. (2003) Plantar fasciitis. A degenerative process
(fasciosis) without inflammation. J Am Podiatr Med Assoc. 93(3):234-237.
• Duggan, S.A. & Bhat, K.P. (2005) Biomechanics and Analysis of Running Gait. Phys Med
Rehabil Clin N Am. 16:603–621.
• Singh D, Angel J, Bentley G, Trevino SG. (1997) Fortnightly review. Plantar
fasciitis. BMJ 315(7101):172-175
Duggan & Baht (2005) divide the stance phase of the gait cycle into initial heel
contact to midstance, midstance to heel off and heel off to toe off. They
describe the first half of the phase to be force absorbing (pronation), while the
second half of the phase is concerned with propulsion (supination).Typically the
foot is in a supinated position at the point of heel strike, with pronation
occurring as it moves from heel strike to weight acceptance. This period of
pronation results in increased foot mobility, which is needed to absorb ground
reaction forces and adapt to uneven terrain, with maximum pronation occurring
at the end of the weight acceptance phase (Bolga et al., 2004). From midstance
through toe-off, the foot supinates, allowing the foot to transform into a rigid
lever arm needed for propulsion.
By virtue of its anatomical orientation and tensile strength the plantar fascia
plays an integral part in preventing the flattening of the medial longitudinal
arch during the heel contact to midstance phases. Both vertical forces from
body weight travelling downward via the tibia and ground reaction forces
Figure 1: A side and inferior view of the plantar aponeurosis of the left foot. Degenerative
changes indicated at the insertion. Adapted from Bolgla & Malone (2004)