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)