The pain from plantar fasciitis is often felt on the bottom of the foot with the first few steps in the morning. It affects approximately 2 million Americans each year. In this article, I will briefly describe what plantar fasciitis is, common symptoms of plantar fasciitis, and how to identify 5 causes of plantar fasciitis.
What is plantar fasciitis?
The plantar fascia is a band of connective tissue on the bottom of the foot that connects the heel to the toes.
It provides support and structure to the foot while walking or running. The function of the foot is very important for balance, strength, and keeping joints healthy.
Unfortunately, the plantar fascia can be over-strained resulting in pain at the insertion of the plantar fascia on the bottom of the heel. It’s one of the most common foot injuries that can limit your quality of life.
Plantar fasciitis affects nearly 2 million Americans per year.
What are the symptoms of plantar fasciitis?
- Pain on the bottom of the heel
- Pain with the first few steps in the morning
- Pain with walking, running, jumping or placing weight on the foot
- Pain after prolonged inactivity
What factors contribute to plantar fasciitis?
The research does not clearly identify the “cause” of plantar fasciitis. The causes of plantar fasciitis are related to a multitude of factors. For example, repetitive stress on the plantar fascia can lead to a breakdown of the plantar fascia.
Breakdown of the plantar fascia is commonly associated with plantar fasciitis; however, the breakdown is not necessarily the source of the pain.
People who have a breakdown of their plantar fascia can still restore pain-free function to their foot. The human body has an incredible capacity to heal and recover from injuries naturally without surgery, injections or pain medications.
Rather than discuss "causes" of plantar fasciitis, we will discuss the "contributing factors."
Plantar fasciitis has many contributing factors.
Contributing Factor #1: Too Much Load
Over-straining the plantar fascia beyond the capacity of the plantar fascia to tolerate those loads can result in pain or injury. The concept of balancing load with tissue capacity is relevant to most injuries and it likely the most important factor in recovering from plantar fasciitis.
Load > tissue capacity = Injury
Once the load exceeds the tissue’s capacity to tolerate that load, an injury is more likely to occur. Loading the plantar fasciitis appropriately is essential to staying pain-free and reducing your risk of injury.
I know it may seem a little confusing to understand what I mean by load. Load is simply a word used to describe the strain placed on the plantar fascia. Here are two examples of activities that could be potential causes of plantar fasciitis.
Examples of Too Much Load
Scenario #1- Running a 5K
You decide to run a 5K race without training for it. During and after the race, you feel a sharp pain at the bottom of your heel.
Unfortunately, you did not train the foot to tolerate the loads of running a 5K.
As a result, the plantar fascia can be over-strained and you may feel pain.
Scenario #2 – Starting a new job
You start a new job as a coffee shop barista. The new job requires many hours of prolonged standing or walking.
A rapid increase in the hours you spend standing or walking places a sudden increased load on the plantar fascia.
If your foot is not accustomed to the increased load, then you may develop plantar fasciitis.
The factors below also contribute to the amount of load placed on the plantar fascia. It is important to stay within the limits of what the plantar fascia can tolerate to avoid injury.
Contributing Factor #2: Increased Body Mass Index (BMI) - except for athletic populations
Studies show that body mass index (BMI) in non-athletic populations is correlated with plantar fasciitis. Those who had a BMI >30 were 5 times more likely to get plantar fasciitis compared to those with a BMI < 25.
An increased BMI can lead to more load and strain on the plantar fascia. The results of this study make a case that reducing BMI can have a beneficial effect to reduce the risk of getting plantar fasciitis.
A BMI calculator will help you determine your BMI. Test yourself and see if you have a high BMI.
Those who had a BMI >30 were 5 times more likely to get plantar fasciitis compared to those with a BMI < 25.
Contributing Factor #3:
Decreased lower leg and foot strength
Strength has a significant contribution to plantar fasciitis. Weakness in the lower leg and foot can increase the amount of strain on the plantar fascia and be one of the potential causes of plantar fasciitis.
The muscles of the lower leg can absorb the load on the plantar fascia to reduce the amount of strain placed directly on the plantar fascia.
Therefore, it will be beneficial to focus on exercises that strengthen the lower leg and foot to recover from plantar fasciitis.
Example of a strength test for the lower leg:
Calf Strength Test
The image on the left shows the heel raise test. The heel raise test is used to determine if you have adequate strength in the calf muscles. Weakness may play a role in your pain.
As a reference, a 40-49-year-old male should be able to complete 32 heel raises.
A 40-49-year-old female should be able to complete 24 heel raises.
Contributing Factor #4:
Restricted mobility in the ankle and foot are potential causes of plantar fasciitis. Adequate mobility in these structures will promote the long-term health of the plantar fascia.
There are three key areas to focus on:
1) Calf tightness
2) Decreased ankle range of motion
3) Big toe stiffness
It is common for people to have tightness in the calf muscle. Tightness in the calf muscles can be an underlying cause of plantar fasciitis in some people although the research is not conclusive on this finding.
Calf stretching and strengthening will help to reduce tightness in the calf and decrease the amount of stress on the plantar fascia.
Examples of exercises to stretch the calf muscles:
Calf stretch with the knee straight
Stand with one foot in front of the other. The front knee should be bent and the back knee should be straight. Make sure the arch of the foot does not collapse. The stretch should be felt in the calf of the back leg.
Calf stretch with the knee bent
Stand with one foot in front of the other. The stance is more narrow compared to the stretch on the left. The front and back knee should be bent. The stretch should be felt in the lower part of the calf of the back leg.
Decrease ankle range of motion
Limited motion of the ankle joint can lead to more strain on the plantar fascia. Exercises to improve the mobility of the ankle joint will help to reduce strain on the plantar fascia.
The ankle mobility wall test is a great way to check mobility in the ankle joint. Your physical therapist can help you perform and interpret this test properly.
The ankle mobility wall test:
Start with the toes of the front foot 5 inches from the wall.
Lunge forward and try to touch the front knee to the wall. Do not let the arch of the foot collapse or the knee move inward.
The inability to touch the knee to the wall shows a decrease in ankle mobility. A decrease in ankle mobility can be a potential cause of plantar fasciitis.
Big toe mobility
The big toe should be able to extend backward approximately 45-70 degrees. The amount of mobility required from the big toe depends on the activity you are doing.
A lack of mobility from the big toe can jam the joint while walking, running, and lunging, etc.
Check your big toe mobility:
Take off your socks and shoes. Cross your leg and pull back on the big toe.
The big toe should extend back approximately 45-70 degrees.
A lack of big toe extension can lead to problems in the foot including plantar fasciitis.
Contributing Factor #5
The position of the foot is much different wearing high heels compared to wearing sandals. A long night out wearing high heels has an effect on the lower leg and feet. You have probably felt that effect after walking with heels for a few hours.
A quick commentary about cushioned shoes vs. minimalist shoes:
Cushioned shoes provide structural stability to the foot. Minimalist shoes provide little support to the foot. There is more reliance on the muscles of the lower leg and foot to support the structure of the foot with minimalist shoes compared to cushioned shoes.
I want you to realize that the type of shoes you wear plays a role with plantar fasciitis. If you are switching to new shoes, then the switch should be gradual to allow time for the foot and lower leg to adapt.
Overall, the causes of plantar fasciitis are not clearly defined in the research because there are many contributing factors. It appears mostly related to the inability of your body to tolerate the demands placed on the foot.
The contributing factors above may or may not apply to your specific situation. An assessment by a physical therapist will help you find the most relevant factors to help you recover.
Thankfully, you can build resiliency in the foot by strength training and modifying your activity levels. Over time, you will recover from plantar fasciitis through a progressive strength training program.
What are your next steps?
If you are struggling with pain on the bottom of the foot then schedule an assessment with a physical therapist.
Get started with a strengthening program to recover from plantar fasciitis and improve your quality of life.
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Read these articles to learn more about plantar fasciitis:
1. Heel Pain—Plantar Fasciitis. Thomas G. McPoil, et. al. Journal of Orthopaedic & Sports Physical Therapy 2008 38:4, A1-A18
2. Lim, A., How, C., & Tan, B. (2016). Management of plantar fasciitis in the outpatient setting. Singapore Medical Journal,57(04), 168-171. doi:10.11622/smedj.2016069
3. Nahin RL. Prevalence and pharmaceutical treatment of plantar fasciitis in United States adults. Journal of Pain. March 26, 2018. Epub ahead of print.
4. Lemont H, Ammirati KM, Usen N. Plantar fasciitis: a degenerative process (fasciosis) without inflammation. J Am Podiatr Med Assoc 2003; 93:234.
5. Cole C, Seto C, Gazewood J. Plantar fasciitis: evidence-based review of diagnosis and therapy. Am Fam Physician 2005; 72:2237.
6. Rathleff MS, Mølgaard CM, Fredberg U, et al. 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.