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)