By Patricia Pande, MClScPT, CSCS, CPed
Running is a hugely popular form of exercise due to its low-cost investment, accessibility of appropriate environments, and obvious health benefits. As running has become mainstream, so has the prevalence of plantar fasciitis or fasciopathy. The incidence of lower extremity injuries in runners is estimated to range from 4.5% to 10% and the prevalence from 5.2% to 17.5%.1
Taunton et al2 and Lopes et al1 have noted the absence of prospective studies of running populations; Taunton et al, however, observed that a higher number of male runners (54%) than female runners (46%) injure the plantar fascia. In fact, plantar fascia injury is the third-most frequent complaint of runners visiting sports medicine clinics. Unfortunately many relevant studies have not uniformly defined running injuries or running populations.3
Anatomy and diagnosis
The fascia divides into medial, central, and lateral bands that attach to the abductor hallucis, flexor abducto brevis, and abductor digiti minimi. The windlass mechanism transfers tension from the proximal attachment of the fascia to its insertion on the calcaneus, which causes the calcaneus to invert and turns the foot into a rigid lever.4-7 The plantar fascia may become inflamed from repetitive stress or undergo degenerative changes, commonly called fasciosis.
Plantar fasciitis presents as pain in the plantar heel at the medial calcaneal tubercle and is most noticeable with the first step in the morning. This pain intensifies with long periods of standing and may be exacerbated with plantar fascia stretching. Although the two may coexist, plantar fasciitis (or fasciopathy) should be differentiated from plantar fat pad atrophy (FPA), which presents as increased pain with weightbearing and compression over the center of the heel.8
Plantar fasciitis in runners
The literature cites a number of causes of plantar fasciitis in runners, including long plantar arch alterations, rearfoot pronation, and magnitude of plantar loads.2,9-12 Plantar fasciitis in runners can also be associated with fasciosis.13-15
Muscle atrophy. Several studies suggest an association between plantar fasciitis and muscle atrophy, particularly of the intrinsic foot muscles. Chang et al found that forefoot muscle volume, assessed using magnetic resonance imaging (MRI), was significantly lower in the affected limbs of patients with unilateral plantar fasciitis than in the healthy limbs.16 In another MRI study, Cheung et al found that rearfoot intrinsic muscle volume was lower in experienced runners with chronic plantar fasciitis than in healthy runners, while forefoot muscle volume was similar between groups.17 Kibler et al also found that runners with plantar fasciitis had significantly worse ankle plantar flexion strength than healthy runners;18 this weakness could be related to muscle atrophy or to reflex inhibition with increased load on the plantar fascia.
Although these studies do not confirm muscle atrophy as the cause of plantar fasciitis or that strengthening exercises will relieve symptoms, research does suggest that intrinsic muscle activation from forefoot contact to toe off may reinforce ligamentous structures.19 Further studies are needed to evaluate the effectiveness of exercises to improve muscle activity and orthotic interventions to support the foot for generation of muscle power.
Plantar loads. Recently, Ribeiro et al found lower loading rates in runners with acute plantar fasciitis (pain for more than four months) than in chronic cases (diagnosed a mean of 1.5 years earlier, presenting with fascial abnormalities but no acute inflammation or pain). However, loading rates in all runners with plantar fasciitis were higher than in healthy runners.20 The authors hypothesized that the lower loading rates in the symptomatic runners than in the chronic group were due to a pain-avoidance response, and that higher loading rates in the chronic plantar fasciitis group were due to the loss of a protective mechanism against pain in the degenerated tissue, as well as a reduced ability to attenuate shock.
Similarly, Pohl et al found that maximum instantaneous load rate was significantly higher in female runners with a history of plantar fasciitis than in control runners.9 Changes in tissue stiffness and fat pad atrophy may contribute to higher loads and may further complicate treatment by reducing lubrication and shock absorption.8 Furthermore, loads related to the running surface may also contribute to plantar fasciitis.21
Running pace and volume. There is conflicting information about the impact of running pace and volume on the risk of injuries, including plantar fasciitis.22 A study by Knobloch et al23 found that marathon runners have a lower risk of plantar fasciitis than runners of shorter distances, which suggests faster pace may be a risk factor and higher volume may be protective. However, other prospective studies have linked lower extremity injuries, including plantar fasciitis, to higher running volume.24 Whether due to pace or volume, the resulting stress may overload tissue.22
Structural variables. Thickening of the plantar fascia has been associated with plantar fasciitis, and may arise from a combination of bending, compression, and shearing forces from muscle weakness or from degenerative thickening.12 Wearing et al found that thicker fascial structures were associated with a lower arch in patients with plantar fasciitis but not in healthy controls;12 it is still not clear whether this finding suggests that having a low arch causes the disability or results from gait adaptation.
Root’s theory25 that foot type contributes to plantar fasciitis remains controversial. The fact that the spectrum of foot types does not form a bell-shaped curve complicates the argument, as does the prevalence of subject-specific kinematic variations.3,26 Additionally, the connection between foot structure and plantar fasciitis is unclear.27 Some researchers found a lower arch index with increased range of dorsiflexion in female runners with plantar fasciitis than in their healthy counterparts,13 but others suggest this relationship is not easily defined due to the foot’s adaptability to prevent injury.32 Nielsen et al found no increased risk of running-related injury in novice runners with moderately pronated feet.28 Additional well-controlled randomized prospective studies of homogenous running groups are critical to furthering our understanding of these factors.
Biomechanics. Kinematics and kinetics during walking in individuals with plantar fasciitis differ from healthy volunteers,29 and clinicians should consider the possibility that these or related differences may extend to running. The coupling mechanisms between the hindfoot, tibia, and arch during running are well-documented, but the relationship between segments of the foot is not clearly understood.6,30,31 Still, it is important for clinicians to be aware that treatments or interventions focused on a single aspect of the foot can also affect other aspects of the kinetic chain.
The American Physical Therapy Association’s clinical practice guidelines for treatment of plantar fasciitis combine stretching, activity limitation, iontophoresis, night splints, and prefabricated or custom inserts.32 The American College of Foot and Ankle Surgeons recommends initial treatment with ice, stretching, ergonomics, off-the-shelf arch supports, nonsteroidal anti-inflammatory drugs, and corticosteroid injections, with progression to custom foot orthoses and physical therapy if little or no improvement after six months.33
Inserts must be able to absorb ground reaction forces, particularly in runners. Prefabricated and customized EVA (ethylene vinyl acetate) orthotic devices were associated with similar levels of pain relief in patients with noncomplicated plantar fasciitis after eight weeks.34 Interestingly, another study found reduction of plantar pressures at the heel associated with two types of EVA sham orthoses (flat and contoured) were similar to those associated with custom foot orthoses—a finding the authors attributed to the attenuating and pressure-redistributing properties of EVA.35 The findings of Pfefffer et al also support the use of less rigid orthotic devices in this patient population; felt and silicone or rubber were more likely to be associated with symptom relief than more rigid devices.36
The use of orthoses to control or supplement motions has been the traditional mainstay of treating runners and nonrunners with plantar fasciitis. Research has demonstrated that orthotic devices are associated with kinetic and kinematic effects in healthy runners. One study showed a decrease in forefoot to rearfoot coupling angles with the use of foot orthoses,37 and another showed a change in rearfoot eversion angle and eversion velocity in female distance runners.38 Mündermann et al found that molded foot orthoses and molded and posted foot orthoses both reduced vertical loading rates and ankle inversion moments in healthy runners.39 However, researchers have not yet determined whether similar biomechanical effects can be expected in runners with plantar fasciitis, or to what extent those changes might affect patient symptoms.
Recent studies in which workload or strain causes pain in connective and muscular tissue support interventions to reduce kinetic effects on such tissue.40 Nigg’s Preferred Movement Pathway theory stresses force reduction and advocates self-selection based on comfort;3,41 however, this and other similar theories need vigorous scientific inquiry.
Conclusions and recommendations
Clinicians should advocate for the cost-effective, judicious use of foot orthoses for runners with plantar fasciitis, in accordance with the present body of knowledge, which suggests such devices should:
- be comfortable42
- provide shock absorption35,36
- not increase torque at other lower extremity joints43
- fit well in the shoe without hindering use of the toe flexors and intrinsic muscles44
- be semicustomizable for patient comfort; and
- address any compensatory adaptations.
Future studies should continue to assess the kinematic causes and effects of plantar fasciitis in the running population, along with factors that predict positive response to treatment.
Patricia Pande, MClScPT, CSCS, CPed, is a physical therapist, pedorthist, strength and conditioning specialist, and founder of FootCentric, an online continuing education company dedicated to comprehensive, multidisciplinary foot treatment.
- Lopes AD, Hespanhol Júnior LC, Yeung SS, Costa LL. What are the main running-related musculoskeletal injuries? A systematic review. Sports Med 2012;42(10):891-905.
- Taunton JE, Ryan MB, Clement DB, et al. A retrospective case-control analysis of 2002 running injuries. Br J Sports Med 2002;36(2):95-101.
- Nigg BM, Baltich J, Hoerzer S, Enders H. Running shoes and running injuries: mythbusting and a proposal for two new paradigms: ‘preferred movement path’ and ‘comfort filter.’ Br J Sports Med 2015;49(20):1290-1294.
- Hicks JH. The foot as a support. Acta Anatomica 1955;25(1):34-45.
- Sarrafian SK. Functional characteristics of the foot and plantar aponeurosis under tibiotalar loading. Foot Ankle 1987;8(1):4-18.
- Wilken J, Rao S, Saltzman C, Yack HJ. The effect of arch height on kinematic coupling during walking. Clin Biomech 2011;26(3):318-323.
- Garcia CA, Hoffman SL, Hastings MK, et al. Effect of metatarsal phalangeal joint extension on plantar soft tissue stiffness and thickness. Foot 2008;18(2):61-67.
- Yi TI, Lee GE, Seo IS, et al. Clinical characteristics of the causes of plantar heel pain. Ann Rehabil Med 2011;35(4):507-513.
- Pohl MB, Hamill J, Davis IS. Biomechanical and anatomic factors associated with a history of plantar fasciitis in female runners. Clin J Sport Med 2009;19(5):372-376.
- Ribeiro AP, Trombini-Souza F, Tessutti VD, et al. The effects of plantar fasciitis and pain on plantar pressure distribution of recreational runners. Clin Biomech 2011;26(2):194-199.
- Wearing SC, Smeathers JE, Urry SR. The effect of plantar fasciitis on vertical foot-ground reaction force. Clin Orthop 2003(409):175-185.
- Wearing SC, Smeathers JE, Sullivan PM, et al. Plantar fasciitis: are pain and fascial thickness associated with arch shape and loading? Phys Ther 2007;87(8):1002-1008.
- Rome K, Webb P, Unsworth A, Haslock I. Heel pad stiffness in runners with plantar heel pain. Clin Biomech 2001;16(10):901-905.
- Grasel RP, Schweitzer ME, Kovalovich AM, et al. MR imaging of plantar fasciitis: edema, tears, and occult marrow abnormalities correlated with outcome. Am J Roentgenol 1999;173(3):699-701.
- Chen YN, Chang CW, Li CT, et al. Finite element analysis of plantar fascia during walking: a quasi-static simulation. Foot Ankle Int 2015;36(1):90-97.
- Chang R, Kent-Braun JA, Hamill J. Use of MRI for volume estimation of tibialis posterior and plantar intrinsic foot muscles in healthy and chronic plantar fasciitis limbs. Clin Biomech 2012;27(5):500-505.
- Cheung RT, Sze LK, Mok NW, No GY. Intrinsic foot muscle volume in experienced runners with and without plantar fasciitis. J Sci Med Sport 2015 Nov 22. [Epub ahead of print]
- Kibler WB, Goldberg C, Chandler TJ. Functional biomechanical deficits in running athletes with plantar fasciitis. Am J Sports Med 1991;19(1):66-71.
- Mann R, Inman VT. Phasic activity of intrinsic muscles of the foot. J Bone Joint Surg Am 1964;46:469-481.
- Ribeiro AP, João SM, Dinato RC, et al. Dynamic patterns of forces and loading rate in runners with unilateral plantar fasciitis: a cross-sectional study. PLoS One 2015;10(9):e0136971.
- Hotta T, Nishiguchi S, Fukutani N, et al. The association between plantar heel pain and running surfaces in competitive long-distance male runners. J Sports Med Phys Fitness 2015 May 5. [Epub ahead of print]
- Nielsen RO, Nohr EA, Rasmussen S, Sørensen H. Classifying running-related injuries based upon etiology, with emphasis on volume and pace. Int J Sports Phys Ther 2013;8(2):172-179.
- Knobloch K, Yoon U, Vogt PM. Acute and overuse injuries correlated to hours of training time in master running athletes. Foot Ankle Int 2008;29(7):671-676.
- Macera CA, Pate RR, Powell KE, et al. Predicting lower-extremity injuries among habitual runners. Arch Intern Med 1989;149(11):2565-2568.
- Root ML, Orein WP, Weed JH. Normal and abnormal function of the foot. Los Angeles: Clinical Biomechanics Corporation; 1977.
- Aström M, Arvidson T. Alignment and joint motion in the normal foot. J Orthop Sports Phys Ther 1995;22(5):216-222.
- Cowan DN, Jones BH, Robinson JR. Foot morphologic characteristics and risk of exercise-related injury. Arch Fam Med 1993;2(7):773-777.
- Nielsen RO, Buist I, Parner ET, et al. Foot pronation is not associated with increased risk in novice runners wearing a neutral shoe; a one-year prospective cohort study. Br J Sports Med 2014;48(6):440-447.
- Chang R, Rodrigues PA, Van Emmerik RE, Hamill J. Multi-segment foot kinematics and ground reaction forces during gait of individuals with plantar fasciitis. J Biomech 2014;47(11):2571-2577.
- Nigg BM, Cole GK, Nachbauer W. Effects of arch height of the foot on angular motion of the lower extremities in running. J Biomech 1993;26(8):909-916.
- Nawoczenski DA, Saltzman CL, Cook TM. The effect of foot structure on the three-dimensional kinematic coupling behavior of the leg and rear foot. Phys Ther 1998;78(4):404-416.
- McPoil TG, Martin RL, Cornwall MW, et al. Heel pain–plantar fasciitis: clinical practice guidelines linked to the international classification of function, disability, and health from the orthopedic section of the American Physical Therapy Association. J Orthop Sports Phys Ther 2008;38(4):A1-A18.
- Thomas JL, Christensen JC, Kravitz SR, et al. American College of Foot and Ankle Surgeons heel pain committee. The diagnosis and treatment of heel pain: A clinical practice guideline-revision 2010. J Foot Ankle Surg 2010;49(3 Suppl):S1-S19.
- Baldassin V, Gomes CR, Beraldo PS. Effectiveness of prefabricated and customized foot orthoses made from low-cost foam for noncomplicated plantar fasciitis: a randomized controlled trial. Arch Phys Med Rehabil 2009;90(4):701-706.
- McCormick CJ, Bonanno DR, Landorf KB. The effect of customised and sham foot orthoses on plantar pressures. J Foot Ankle Res 2013;17(6):19.
- Pfeffer G, Bacchetti P, Deland J, et al. Comparison of custom and prefabricated orthoses in the initial treatment of proximal plantar fasciitis. Foot Ankle Int 1999;20(4):214-221.
- Eslami M, Ferber R. Can orthoses and navicular drop affect foot motion patterns during running? J Sci Med Sport 2013;16(4):377-381.
- MacLean C, Davis IM, Hamill J. Influence of a custom foot orthotic intervention on lower extremity dynamics in healthy runners. Clin Biomech 2006;21(6):623-630.
- Mündermann A, Nigg BM, Humble RN, Stefanyshyn DJ. Foot orthotics affect lower extremity kinematics and kinetics during running. Clin Biomech 2003;18(3):254-262.
- Williams DS 3rd, McClay Davis I, Baitch SP. Effect of inverted orthoses on lower-extremity mechanics in runners. Med Sci Sports Exerc 2003;35(12):2060-2068.
- Nigg BM, Nurse MA. Stefanyshyn DJ. Shoe inserts and orthotics for sports and physical activities. Med Sci Sports Exerc 1999;31(7 Suppl):S421-S428.
- Mündermann A, Nigg BM, Humble RN, Stefanyshyn DJ. Orthotic comfort is related to kinematics, kinetics, and EMG in recreational runners. Med Sci Sports Exerc 2003;35(10):1710-1719.
- Franz JR, Dicharry J, Riley PO, et al. The influence of arch supports on knee torques relevant to knee osteoarthritis. Med Sci Sports Exerc 2008;40(5):913-917.
- Morita N, Yamauchi J, Kurihara T, et al. Toe flexor strength and foot arch height in children. Med Sci Sports Exerc 2014;47(2):350-356.