Plantar fasciitis is the most commonly reported cause of inferior heel pain, with an estimated prevalence ranging from 3.6% to 7% in the general population. In runners, it is one of the most common injuries, accounting for up to 8% of all running-related injuries.” (2)
The plantar fascia is a dense, fibrous band serving as a biomechanical force transducer as well as a protector to the vulnerable neurovascular structures on the plantar aspect of the foot. Its primary function is to support the arch of the foot while stationary as well as shock absorption during movement. Development of rehabilitation exercises for plantar fasciitis requires understanding of the (1) biomechanics of the windlass mechanism and (2) etiology and the condition.
Biomechanics: The PF band’s proximal origin is the medial calcaneal tubercle, and its distal attachments are all five toes. The band functions, via the windlass mechanism to stabilize the foot during gait- i.e., at heel strike, the plantar fascia is slack to allow the foot to accommodate uneven surfaces. As the heel lifts and forefoot dorsiflexes toward toe off, the distal plantar fascia winds up and around the first MTP joint pulling the plantar fascia taut, shortening the distance between the heel and forefoot, raising the arch– creating a stiffer lever for propulsion. Understanding this mechanism drives exercise prescription to improve tissue strength and capacity.
Etiology: Fasciosis and tendinosis are degenerative processes involving type I collagen fibers. Stressing collagen fibers beyond their capacity not allowing ample time for recovery leads to injury. This process is consistent in other areas of the body like Patellar and Achilles tendinopathy. Keep in mind; facial injuries can arise in both active and sedentary individuals. Most commonly, PF begins with prolonged weight bearing, (standing or running) resulting in biomechanical overuse leading to microtears at the calcaneal enthesis. The diagnosis of “plantar fasciitis” encompasses disorders ranging from acute inflammation to chronic fibrotic degeneration, usually involving the calcaneal attachment. (1,2) The term fasciitis, commonly used in the literature, is likely a misnomer; fasciosis or fasciopathy might be more appropriate terms. The term, “plantar fasciitis” implies inflammation, more recent studies suggest that plantar fascia pain results from a non-inflammatory, degenerative process. Initial insults may generate an acute inflammatory reaction, but repetitive chronic overload results in a breakdown of the inflammatory process and a disorganized healing process that fails to regenerate “normal” tissue.
High Load Strength Training (HLST) is a proven method to rebuild and strengthen degenerated tissue like plantar fasciosis.
The purpose of HLST is to stress a tendon with a high tensile load to stimulate collagen production and, ultimately, expedite recovery. In patients with PF, loading of the Achilles tendon in conjunction with dorsiflexion of the metatarsophalangeal joints (windlass mechanism) generates high-load tensile forces across the plantar fascia synergistically (2) Caratun et al. recommend 1 set of 10 repetitions per day for weeks 1-4. The authors recommend using the unaffected leg to assist in the concentric phase of movement if the patient is unable to perform at least ten repetitions unassisted per day. During weeks 5-12, the patient adds resistance. The authors recommend using a book bag with books to achieve repetition maximum (RM) weight -at which the patient can perform ten repetitions with good form, but is muscularly exhausted afterward. This weight will gradually increase with weekly strength gains. (2)
Stressing the plantar fascia through progressive concentric and eccentric resistance exercises stimulates increased collagen synthesis. In patients with PF, this has the potential to heal the degenerative changes seen at the plantar fascia enthesis, leading to a more normalized tendon structure, less pain, and ultimately, improved patient outcomes. An additional benefit observed in individuals who participate in this protocol is the potential for increased ankle dorsiflexion strength counteracting the typical decline in ankle dorsiflexion strength in those with PF. (2)
Rathleff et al. (2015) demonstrated superior self-reported outcome after three months with HLST exercises compared with traditional plantar-specific stretching. High-load strength training may aid in a quicker reduction in pain and improvements in function. (3)
Every patient deserves “best practice” treatment, rehabilitation, advice, and condition specific education. As an evidence-informed provider, you must develop processes within your practice to be confident your patients are receiving best possible care. One of the benefits of ChiroUp is to learn form the top providers around the world. Check out the Expert Advice section within the ChiroUp condition references to learn more about what the top providers are doing for plantar fasciitis.
- Digiovanni BF, Nawoczenski DA, Malay DP, Graci PA, Williams TT, Wilding GE, et al. Plantar fascia-specific stretching exercise improves outcomes in patients with chronic plantar fasciitis. A prospective clinical trial with two-year follow-up. J Bone Joint Surg Am. 2006;88(8):1775–81.
- Robert Caratun, Nicole Anna Rutkowski, Hillel M. Finestone. Can Fam Physician. 2018 Jan; 64(1): 44–46.
- S. Rathleff, C. M. Mølgaard, U. Fredberg, S. Kaalund, K. B. Andersen, T. T. Jensen, S. Aaskov, J. L. Olesen. High-load strength training improves outcome in patients with plantar fasciitis: A randomized controlled trial with 12-month follow-up Scand J Med Sci Sports 2015: 25: e292–e300
About the Author
Dr. Tim Bertelsman
DC, CCSP, DACO
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