Point-Counterpoint: Stretching: Is It Beneficial For Plantar Fasciitis?
Stretching may be the most frequently recommended treatment for plantar fasciitis (fasciopathy).1,2 Several articles highly recommend calf stretching and specific plantar fascial stretching.3 But is stretching right for every case of plantar fasciitis? Is it always correct to recommend stretching? Without any reservations but with some nuance, I will say no.
Is more stretching the only conservative therapy we have to offer the patient who visits after six months of dutiful stretching? The wisdom of the Internet would lead us to rolling with a golf ball, icing, more stretching and over-the-counter inserts for plantar fasciitis. We can do better.
Some studies using stretching as sole therapy have focused on patients who have had plantar heel pain for less than six weeks, limited to one foot and have had no prior therapy. A recent study compared plantar-fascia specific stretching with shockwave therapy for the initial treatment of unilateral plantar fasciopathy for an average of four weeks.4 The authors found that “stretching” the plantar fascia was superior to shockwave at the four-month mark but had no superiority at 15 months. The study excluded nearly a third of the patients selected as they refused to sign the consent form for the study. In addition, 10 to 15 percent of the study patients became lost to follow-up for the data acquired at 15 months.
If stretching has had minimal impact, we need to evaluate our therapy and change it. The literature of chronic plantar fasciitis usually looks to solutions that involve other modalities besides stretching.
What Are The Key Characteristics Of The Plantar Fascia?
The plantar fascia is primarily made up of linearly oriented fibers mainly comprised of collagen. A recent study demonstrated that the fibers run primarily proximal to distal with layers of fibers oriented vertically, transversely and obliquely.5 This multilayered structure is characteristic of a tissue that has much of the nature of a “fascia” and not an aponeurosis. The strain resistance characteristics of the plantar fascia are much stronger than much of other fascia and the plantar fascia’s strain resistance is similar to the iliotibial band.6
The plantar fascia, in part, functions as a windlass mechanism and much biomechanical theory posits that the foot needs to act as a mobile adaptor at contact and as a rigid lever at the propulsive phase of gait.7 The fascia elongates as the foot proceeds through midstance and more strain develops as the heel leaves the ground and the digits dorsiflex.8 The plantar fascia and plantar muscles absorb the loading forces as elastic strain energy early in gait and return it later as passive elastic recoil.7,9 Importantly, the plantar fascia and plantar muscles contribute to the function of the foot as a rigid lever. Stiffness is an important and needed feature of the longitudinal arch late in gait. The plantar fascia and the windlass mechanism are the major contributors to this stiffness.
Researchers have long hypothesized that the plantar intrinsic foot muscles contribute to resisting loading forces and act to increase the height of the longitudinal arch. Only recently have researchers been able to test and demonstrate that activation of three plantar intrinsic muscles (the abductor hallucis, flexor digitorum brevis and quadratus plantae) had this effect.10 Electrical stimulation of the plantar muscles acts to counter the deforming force of an external load and resist the lengthening of the “arch” and lowering that would otherwise occur. Earlier models often emphasized the function of the plantar fascia but added a “viscous damper” to the model and worked on the premise of the plantar intrinsic muscles acting parallel to the plantar fascia.11
Anatomical and histological studies of the plantar fascia show that Pacinian and Ruffini corpuscles are present in the plantar fascia.5 This indicates that the plantar fascia may play a role in foot proprioception and perhaps in triggering muscle function and coordination. Through this mechanism, the plantar fascia may contribute to overall balance and posture.