Plantar Fasciitis – Part 1 – Causes and prevention strategies
These two words strike fear into people either because they have suffered with it, or they have seen friends suffering from it. As well-known a term as plantar fasciitis (PF) is, particularly in sporting communities, there are a lot of misconceptions about it, which leads to people having treatments that have been shown to have negligible or only short-term effect. This is troubling, as there is high-quality researched treatment out there that can help you manage, if not recover, from this debilitating problem! In fact, some of the research gives us ideas on how we might prevent it from happening. This blog will explain what PF is, how it becomes a problem, and what we can do about it!
What is the Plantar Fascia, what does it do, and what is Plantar Fascitis?
The plantar fascia is a connective tissue that runs from the heel to the base of the toes along the undersurface of the foot. It is made up of three distinct cords, medial, lateral, and central. There is a connection between the plantar fascia and the achilles tendon via a thin layer of fibers over the heel bone (calacaneus). It is thought that this connection thins with age. The collagen fibers of the plantar fascia are very strong and predominantly run longitudinally. It is so strong that to increase its length by 1% requires over a ton (2,040 lbs) force1 being placed on it! The plantar fascia as well as having these strong fibers is also well innervated by nerve endings that help us detect mechanical stimuli such as pressure.
The importance of the plantar fascia is in a mechanism called the windlass mechanism first described in 1954. When you go up on tip-toes, you will feel tension develop in the arch of the foot as the windlass mechanism lifts the arch. You will also feel your foot fall outwards into supination. This mechanism helps to maintain the medial (inside) longitudinal arch of the foot, reducing forces on the ligaments and muscles of the foot, and absorbing/releasing energy during running and jumping.
The term plantar fasciitis is an older term and has actually been changed in the research literature to plantar fasciopathy2. The reason this is important is that the suffix “itis” suggested an inflammatory (swelling) process; actually the majority of cases are not inflammatory, but are degenerative. The central cord is the primary area that becomes degenerated. Some may think this is just a case of semantics, however, if we consider it an inflammatory condition, we will treat it as such, which may not have the desired effect! If we assume it is inflammatory and try and treat it ourselves with things such as ice and anti-inflammatories, the problem may stay, or get worse, and may then be harder to treat when we get professional help.
Who gets it?
Heel pain will affect 10% of people over a lifetime and will lead to 1 million visits to doctors in the US3! Of these heel pains, there are many potential diagnoses including issues of the plantar fascia, plantar nerve entrapment, heel fat pad atrophy and others. PF is a well-known condition in runners affecting 31% during 5 years4. 30% of cases will involve both feet5. The peak age occurs between the ages of 40 and 606.
The latest studies have well proven three causes in developing PF
- Thickened plantar fascia7
- High Body Mass Index (BMI)8
- Heel spur7
Other causes have been suggested but not wholly proven such as5:
- Prolonged standing
- Inappropriate footwear
- Previous injuries
- High-load running
- Limited ROM of big toe (metatarsophalangeal joint)
- Limited ankle dorsiflexion
- Asymmetric leg length
- Foot hyper-pronation
- Weakness of calf muscles
- Older age.
At all times there are chemical reactions in the body’s tissues, anabolic (building up), and catabolic (breaking down)9. A certain amount of stress on a tissue is essential for the ratio between these reactions to be such that the tissue will develop to take higher levels of stress10. This process is called mechanotransduction. If the rate of change is too great, the tissue does not have the time to adapt and the load becomes too great, leading to degeneration and associated pain. The rate of change that is placed on the tissue can be training parameters such as magnitude, frequency, rate, and duration of force and strain. Some of these parameters are influenced by everyday training decisions such as speeds, amount of sessions, and rest days. Some are influenced by the strength, flexibility, and ability to control/cue how the body moves.
How do I avoid it?
A thickened plantar fascia and heel spur cannot really be affected without considering surgery, which, in the absence of an issue would be foolhardy! High BMI is something we can affect using diet and exercise. I would suggest that activities such as cycling or swimming can get your heart rate up to a good intensity without placing a high strain on the plantar fascia. If you are a runner with high BMI, and are concerned about the risk of PF, you may chose to reduce your running sessions for a period while you focus on reducing BMI, before gradually increasing running again.
If you do a lot of running or impact sport and are concerned about the potential of PF or other issues such as tendinopathy and stress fractures, it is worth considering how you go about training. Training appropriately allows a good ratio of anabolic:catabolic reactions to occur and for the tissues of the body to gradually acclimatize to the increased activity you are asking of it. A great way to ensure that training is appropriate is to set yourself goals and a plan with manageable progressions. There are three ways you could do this:
- Work with a coach or training group
- Use an online training plan
- Develop your own plan – the old adage of no more than 10% a week is an appropriate guide
Even with this approach it is important to realize that only you can feel how you are progressing. It is thought that a little soreness is a good thing in sport, as it is guiding the body to where resources are needed. For this reason it is worth using good pain guidelines in how to progress and even alter your plan as you go along. I wrote a detailed blog on this last year, but you can see in the diagram below that there are three categories of pain and following these will help reduce the risk of doing too much and risking injury.
I hope that this gives you some idea of why PF can occur and how you might be able to prevent it. If you are nervous about this condition but do not have risk factors, I hope you have gained some confidence to go and do the things you want to do! If you have the risk factors I hope this gives you some general ideas of how to reduce your risk. Stay tuned for Part 2 where we will cover how to treat and recover from PF. If you are unfortunate enough to deal with it – this will include some recent and very promising research that I have seen great results with!
Chaudhry H, Schleip R, Ji Z, Bukiet B, Maney M, Findley T. Three-dimensional mathematical model for deformation of human fasciae in manual therapy. J Am Osteopath Assoc. 2008;108(8):379-90.
Lemont H, Ammirati KM, Usen N. Plantar fasciitis: a degenerative process (fasciosis) without inflammation. J Am Podiatr Med Assoc. 2003;93(3):234-7.
Riddle DL, Schappert SM. Volume of ambulatory care visits and patterns of care for patients diagnosed with plantar fasciitis: a national study of medical doctors. Foot Ankle Int. 2004;25(5):303-10.
Di caprio F, Buda R, Mosca M, Calabro’ A, Giannini S. Foot and lower limb diseases in runners: assessment of risk factors. J Sports Sci Med. 2010;9(4):587-96.
Rajasekaran S, Finnoff JT. Plantar Fasciopathy: A Clinical Review. Current Physical Medicine and Rehabilitation Reports 2015; 3(1): 67-76
Buchbinder R. Clinical practice. Plantar fasciitis. N Engl J Med. 2004;350(21):2159-66.
Mcmillan AM, Landorf KB, Barrett JT, Menz HB, Bird AR. Diagnostic imaging for chronic plantar heel pain: a systematic review and meta-analysis. J Foot Ankle Res. 2009;2:32.
Van leeuwen KD, Rogers J, Winzenberg T, Van middelkoop M. Higher body mass index is associated with plantar fasciopathy/’plantar fasciitis’: systematic review and meta-analysis of various clinical and imaging risk factors. Br J Sports Med. 2015;
Rathleff MS, Thorborg K. ‘Load me up, Scotty’: mechanotherapy for plantar fasciopathy (formerly known as plantar fasciitis). Br J Sports Med. 2015;49(10):638-9.
- Khan KM, Scott A. Mechanotherapy: how physical therapists’ prescription of exercise promotes tissue repair. Br J Sports Med. 2009;43(4):247-52.m effectiveness. A randomized controlled trial. Rheumatology (Oxford). 1999;38(10):974-7.
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