Functional biomechanical deficits in running athletes with plantar fasciitis. (1991)

Abstract
Plantar fasciitis is a relatively common injury that occurs in running athletes. The disease entity is a good example of an overloaded process of the plantar fascia at its calcaneal insertion. This study was designed to examine the strength and flexibility findings in the muscles that are put on tensile load during running, and which are responsible for controlling the forces on the foot during stance and pushoff, thus modifying the overload. Three groups of athletes underwent physical examination, including checking ankle range of motion in plantar flexion and dorsiflexion. Cybex peak torque measurements were taken at 60 and 180 deg/sec. The groups were a control group of 45 athletes with no symptoms, a group that included 43 affected feet with symptomatic plantar fasciitis, and a group that included the 43 unaffected contralateral feet. Analysis of data showed dynamic range of motion deficits in 38 of 43 affected feet, static range of motion deficits in 37 of 43 affected feet, deficits in peak torque at 60 deg/sec in 41 of 43 affected feet, and deficits in peak torque at 180 deg/sec in 37 of 43 affected feet. Statistical comparison of range of motion showed that the group with symptomatic plantar fasciitis was significantly restricted compared to both control and unaffected contralateral feet groups. Statistical comparison of peak torque showed that the symptomatic plantar fasciitis group was significantly lower than both other groups at both velocities. This study documents strength and flexibility deficits in the supporting musculature of the posterior calf and foot that are affected by plantar fasciitis. These anatomical and physiological alterations create a functional deficit in the normal foot biomechanics. This either causes or contributes to the overt clinical symptoms and should be addressed in the evaluation and treatment of plantar fasciitis.
Quote from the conclusion:

“The restoration of muscle strength and flexibility of the foot is thought be especially important in light of the findings of Nigg, Nigg, et all, and Robbins et all, which show that very little force can actually be attenuated by modifying the shoes of athletes with otherwise normal feet.”

My Comments:

The last study I blogged on was 11 years old, this one is 23 years old and is the single best paper I have read to date on plantar fasciitis. The research in the paper was both good and pertinent, and the introduction and concluding remarks are IMO spot on, and unfortunately 2/3 ignored.  Such that any physician, podiatrist, or physical therapist specializing in runners injuries or foot pain ought to read the entire text. What the researchers found was average ankle range of motion (ROM) runners with plantar fasciitis was limited 26.9% in their painful side comparison to their good side, but was limited 39% in comparison to healthy runners. Calf muscle strength (peak torque) measured at 60 degrees per second in runners with plantar fasciitis was limited 25.1% in comparison to their good side and limited 33.3% in comparison to healthy controls. They found even the “healthy” foot in runners with plantar fasciitis still had 17.4% less ankle ROM and 11.7% less strength than did control subjects.

The authors clearly thought that strength loss, as well as ROM, was important to recovery of plantar fasciitis, yet today the typical treatment for plantar fasciitis is orthotics (which have minimal effect regardless of cost), stretches, later night splints, cortisone shots, and if that all fails surgery (which itself often fails). In 23 years since this paper there has yet to be controlled trial of foot intrinsic and LE strengthening exercise either alone or in combination with other treatments. That seems amiss to me.