Tag Archives: heel

Ditching the shoes: Minimalist trend or natural advantage?

The discussion of returning to minimalist ways, namely walking or running barefoot, is a question that rises in many circles, from new parents to elite runners. For example, parents are told to let children learn to walk barefoot, as studies have shown early use of footwear can lead to feet deformities and can alter natural gait, which is especially important when learning to walk. Likewise, many avid and elite runners have shown interest in barefoot running (or minimalist running shoes), as some are convinced that the forefront strike (FFS or also known as NRFS – non rear foot strike), more commonly used during barefoot running, lowers the loading rate on the foot and minimizes injuries from the repeated stress that occurs in the feet during running. 

Diagram illustrating four phases of foot contact with the ground for forefront strike and rear foot strike patterns
Forefront strike (top) and rear foot strike (bottom). Modified from Daniel E. Lieberman et al., Springer Nature 2010

In general, walking or running barefoot yields more frequent steps, a smaller stride length and a slower velocity (most noticeable while running). Barefoot running is thought to reduce some of the injuries many runners are prone to, such as shin splints, stress fractures or plantar fasciitis. Additionally, the stiff fit of modern shoes limits the width and spreading of feet in the natural walking or running motion. However, barefoot running also comes with a cost, with injuries in the achilles region more prevalent. 

A study in the Gait & Posture journal examined foot motion in children and found modern commercial footwear does have a large impact on gait, especially in regards to range of motions of different muscles and joints in the foot, likely due to the stiffness of shoes. More flexible shoes, similar to minimalist running shoes, were found to have a smaller impact on foot motion in reference to bare feet, but still had a significant difference in regards to the added support in the arch area. 

The common belief that barefoot motion lowers the impact on the body has been questioned by a recent research study from Southern Methodist University. The findings indicated that while running barefoot with a forefront strike, the feet strike the ground at a more pronounced angle which generates a longer contact time, thus decreasing the loading rate and allowing the muscles in the back of the feet and legs (especially the Achilles) to absorb some of the loading stress. When humans adapted to running in shoes, especially shoes with thick cushioning, the landing switched to a rear foot strike that allows the heel cushioning to absorb some of the loading stress, resulting in a fairly equal loading rate for both cases. The heel cushioning, with a flatter angle of contact, also allows for decreased impact time with the ground surface, which is why higher running speeds are achieved with footwear. 

barefoot person walking outdoors during the day
Photo by ‏🌸🙌 في عین الله on Unsplash

While the advice to encourage barefoot walking in young children certainly makes sense as they continue to grow and learn to control their bodies, the choice to use shoes or go barefoot for older children and adults remains an individual preference. There is no significant difference in the stresses the body experiences, but the footwear choice does influence the likelihood of certain, which is important for runners with past injuries to consider.

For more information, check out this extensive technical review of studies on barefoot vs. footwear mechanics or this video from Exercising Health comparing running shoes with minimalistic barefoot shoes.

Living Off Balance

Person walking in woods, balancing on a fallen tree

Imagine yourself walking at a normal pace down the sidewalk. Maybe you are on your way to class. The sidewalk has a little bit of a tilt causing your left foot to be higher than the right as it plants on the ground. Imagine how your body may compensate after a few minutes of walking on this path. We have all walked on uneven ground and began to feel the effects with sore knees or hips. But what if you felt this same way all the time even on perfectly flat terrain? This is the reality for those with leg length discrepancies.

Leg Length Discrepancy

A leg length discrepancy (LLD) is any difference in your legs compared to one another. This can be as small as a few millimeters or as large as a few centimeters. Leg length discrepancies can be caused by a number of things including genetics, trauma, or disease. Leg length discrepancies can be categorized in two ways; real and apparent LLD. Real leg length discrepancies are one in which the bony structures are measured to be two different lengths. Apparent leg length discrepancies are caused by other factors such as muscle or joint tightness making the limbs appear two different lengths.

Image depicting pelvic tilt when leg length discrepancy is present
Pelvic tilt caused by real leg length discrepancy

Hopping Along

The actual significance of a LLD on posture and gait depends heavily on the magnitude of the discrepancy. It is highly debated by researchers if a LLD of less than 2-3cm has physical effects on the body and if symptoms a patient is experiencing are due to another cause. R.K. Mahar and R.L. Kirby at Dalhousie University performed a study in which people without a LLD, asking them to stand on blocks simulating a real leg length discrepancy, the researchers saw a misalignment of the hips, an increase in knee flexion and a shift in the center of gravity.

In contrast D.C. Reid conducted a study for those with actual LLD and many did not complain of pain or feeling off balance and chose to not use corrective devices. The body is able to compensate for the difference over time to minimize the displacement of the center of mass of the body. It was also seen in a study done by Gross that athletes are more likely to correct smaller LLD than the average person due to the increased loads experienced during their activity.

Lift is placed in the sole of the shoe to correct moderate LLD
Shoe lift place in sole used to correct LLD

Fix it

For people that are experiencing pain because of the difference there are several ways to reduce the pain. For small discrepancies (less than 1cm) inserts can be placed into the shoe to even out the hips. For differences between 1cm and about 5cm a lift can be placed in the sole of the shoe for the same reason as the inserts. For some special cases or discrepancies larger than 5cm corrective surgery to lengthen or shorten the limb can be performed, but this is often used as a last resort.

Hell for your Heels: Plantar Fasciitis and Heel Spurs

Heel and foot pain are somewhat universal issues, impacting people of all different sizes and activity levels. This type of pain can be seen in obese people, who have increased strain on their feet and heels. This pain can limit their mobility, and even discourage healthy amounts of exercise.  It is also common to extremely active people, such as runners or sports players. This type of pain can prevent a person from participating in the athletics that they work so hard to compete in. I experienced a great deal of heel pain during high school, which made it difficult for me to play sports such as soccer, basketball, and track and field. This was an issue I had to deal with throughout high school, however I never understood what caused this pain that kept me on the sidelines at times.

Image showing the plantar fascia ligament and where inflammation is common
Image from Energize Health

By far the most common cause of heel pain is damage to the plantar fascia. The plantar fascia is a ligament connecting the ball of the foot to the heel bone, critical for stability and power in human locomotion. Damage to this ligament is caused by 2 main factors: weight and use. Increased weight, especially over a short period of time, significantly increases the load experienced by the plantar fascia. This increased load pushes the ligament past its yield load and causes tears in the ligament, weakening its mechanical abilities and causing pain. Another important contributor to this ligament’s damage is its workload. Active athletes and runners push this ligament to its limit by regularly undergoing periods of high-intensity loading, causing fatigue failure. In my case, a combination of these two factors caused damage to my plantar fascia: a large growth spurt combined with regular athletics overloaded this ligament, causing damage.

Artist's rendition of the medical conditions plantar fasciitis, where the ligament is damaged and swollen, and heel spurs, where abnormal bone growth is seen to to ligament damage.
Image from 2019 Harvard Health Publishing

This damage to the plantar fascia relates to two resulting conditions: plantar fasciitis and heel spurs. Plantar fasciitis is the swelling of the plantar fascia ligament. This inflammation is caused by the tears and damage as previously discussed, causing sharp pains to the bottom of the foot and heel. Tears in the ligament typically occur at the connection of the bone and ligament. Certain factors can make a person more susceptible to this condition, such as having flat feet or wearing footwear with poor support. In both cases, the plantar fascia is loaded poorly, causing the painful inflammation. There are conflicting studies as to how this condition relates to heel spurs and heel pain.

Heel spurs are calcium deposits located around the connection of the plantar fascia to the heel bone, which cause abnormal bone growth in the area. Heel spurs are caused by prolonged loading and damage to the foot muscle and plantar ligament. Heel spurs are often seen as a result of plantar fasciitis, however the two aren’t mutually exclusive. Heel spurs are found in patients without any evidence of heel pain, raising doubts about how they are directly related. Some studies argue that the heel spurs themselves cause pain, while others contest that they develop in response to plantar fasciitis, the true source of the pain.

These conditions are typically first treated through non-invasive methods. These strategies include specific stretches, targeted exercising, a reduction in workload, and weight loss (if safe). These treatment methods help to improve the mechanical properties of the ligament, making it stronger, less stiff, and less fatigued. Dr. Jarocki from Michigan Medicine gives a thorough and concise summary of the causes of heel pain, as well as some exercises that can help to alleviate this pain.

If these fail, invasive surgery can be required. Surgery can be used to repair the ligament itself or to remove the heel spur. The controversy over the relationship between heel spurs and pain has important implications for the effectiveness of this type of surgery.

Sources and Additional Information:

https://www.health.harvard.edu/a_to_z/heel-pain-a-to-z

https://www.sciencedirect.com/science/article/pii/S1067251601800715

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3309235/

https://www.sciencedirect.com/science/article/pii/S1067251609800653

Put One Foot in Front of the Other? It’s Not that Easy

From Christmas movies to pop songs to motivational posters, we are encouraged to keep putting “one foot in front of the other.” While the sentiment is inspiring, recent studies show that there is a lot more to the seemingly simple task of walking than this phrase would suggest. Understanding this is especially important for balance and mobility after an injury or as people age.

The steps that make up the human walking cycle. Order of steps: heel-strike right, toe-off left, midstance right, heel-strike left, toe-off right, midstance left, hell-strike right. The body spends the time between heel-strike and toe-off with double support and the midstances are single-leg support.

Image from Wikimedia Commons

The human gait has a set structure that switches the weight between each leg, with only 20% of the typical walking motion distributing the weight across both feet. Maintaining balance throughout this process requires coordination in the muscles controlling the hips, knees, ankles, and feet. Mechanically, these adjustments keep the body’s center of mass (also known as center of gravity) over the base formed by feet positioning.

Obstacles and challenges to balance require a body’s quick response to mitigate shifts in the acceleration and momentum at the center of mass. Lack of efficient control over these parameters results in a fall. Many conditions, as well as age, can affect a person’s ability to respond to mobility challenges.

One specific study looked at how people who had had a stroke and subsequent partial paralysis on one side (paresis) faced mobility challenges compared with healthy folks. This condition effects approximately 400,000-500,000 people in the United States annually. It presents a unique opportunity to compare an individual’s non-damaged stride with their deficient stride at the point in the gait at which only one leg is on the ground (SLS, or single-leg-stride). The timing of the gait, the body’s momentum in all three planes of the body, and the location of the center of mass were recorded in this study.

Anatomical planes of the body. The sagittal plane splits the body left and right. The coronal plane splits the body forward and back. The transverse plane splits the body top and bottom.
Image from Wikimedia Commons

Versus healthy people, stroke survivors had significant trouble regulating momentum in the coronal plane, making falls more likely. Although it makes sense that momentum regulation suffers when muscles are paretic, it is yet unclear why the coronal plane was most affected. Additionally, post-stroke individuals’ centers of gravity were higher, which is also linked to instability. For stroke survivors, the partially paralyzed SLS took longer and extended farther from the center of mass than the regular SLS. While this is not as immediately dangerous as increasing falling risk, it slows mobility, unevenly works muscles (which can lead to injury), and is less efficient.

Going forward, these findings can be used to improve mobility success in people with balance issues or after injuries. This could manifest in better technologies, such as walkers that better help settle a person’s center of mass and partial exoskeletons that would help a person mitigate acceleration and momentum changes, or more targeted and individualistic physical therapies to strengthen weakened muscles and practice patient-specific challenges, such as overcoming obstacles that threaten coronal-plane balance. Understanding more about balance adjustment when walking may make some common phrases trite, but its potential benefits have life-changing impacts for many.

Further Reading and Sources:

Stroke/Paresis Information

Stability of Stepping

High Heels: How They Can Affect You Even After You Take Them Off

Anyone who has worn high heels, or has even simply seen a person in high heels, knows that the foot is definitely not in its usual position in that kind of shoe – walking is more difficult and forget about even trying to run in high heels. Researchers from Manchester Metropolitan University and the University of Vienna wanted to investigate if frequent, long term use of high heels caused lasting changes in the calf, in addition to the normal discomfort experienced by high heel wearers. Previous studies have shown that muscles that are regularly used in unusual ways will often adjust to this new scenario to maintain functionality. These researchers, more specifically, investigated whether the regular wearing of high heels would result in physiological changes to the calf (gastrocnemius) muscle and Achilles’ tendon, and if these changes would then affect the normal functioning of the calf and ankle. In order to determine if and what changes occur, the researchers observed a group of women who regularly wore high heels and a control group who did not to compare their calves and ankles.

two women walking in stillettos
Modified Image by StockSnap on Pixabay

The calf muscle and Achilles’ tendon make up the top and bottom of the rear of the calf respectively. They play a crucial role in controlling ankle motion and in general mobility. Dimensions of the muscles, including length, were measured using ultrasound, and the cross sectional areas of the tendons were measured using MRI imaging. The torque and motion of the ankle were measured by an isokinetic dynamometer. From these values, the researches could determine other important characteristics of the tendon such as the force on it, the strain it experienced, the stiffness, and the modulus of elasticity. The strain value indicates how much the tendon is stretched from its relaxed position since it is the ratio of the change in length to the original length. The stiffness is the ratio of the force experienced to the amount of length change the tendon experienced. The modulus of elasticity, or Young’s modulus, is the ratio of how much force per area the tendon experiences to the strain.

muscles and tendons in the calf and ankle
Modified Image on Smart Servier Medical Art

MRI image of the side of two ankles with one having the foot on a wedge mimicking wearing high heels and one having the foot flat on the ground
From Csapo, Maganaris, Seynnes, and Narici, Journal of Experimental Biology 2010

 

The results of their analysis showed that people who regularly wore high heels had a resting ankle position that made the foot further from perpendicular with the leg than that of someone who did not regularly wear high heels. Additionally, generally the calf muscles of high heel wearers were shorter and the stiffnesses of their Achilles’ tendons were higher due to greater cross sectional areas of the tendons. The maximum strain in the Achilles’ tendon was lower in high heel wearers because of the reduction in length. However, no significant difference in the Young’s modulus of the tendon was observed. Similar torque-angle relationships were observed between the two study groups, so the researchers inferred that the body must have compensated for this new positioning. Additionally, these results explain the observation that high heel wearers had a reduced active range of motion in their ankles because of shorter, stiffer muscles and tendons. What the new normal ankle position means for regular high heel wearers is that their bodies are adjusting to shifts in gait, center of mass, and ground reaction forces if they wear high heels very often. The researchers infer that this physical change to the calf can also account for the discomfort women who regularly wear high heels experience when switching to flat shoes.

For additional discussion of this topic, take a look at Discover Magazine.

Back Against the (John) Wall

What would you do if you went to the doctor expecting to get back to work, only to be told you might not ever be able to go back to work again?

According to ESPN, on February 4, John Wall visited his doctor regarding an infection in his heel after a previous operation. The doctor checked the infection, but upon further analysis, realized that Wall had suffered a partial Achilles tear. Unlike former teammate Boogie Cousins, he did not suffer the tear on the court, but at home. It was reported that while at home he fell and experienced extra discomfort in his heel. His doctor reported that he will undergo surgery and will likely rehab for the next 11 to 15 months.

Achilles Ache

The Achilles is a tendon (tissue that attaches muscle to bone) connecting the bottom of one’s calf to the back of the heel, as shown in Figure 1. It is famously named after the Greek hero whose only weakness was the back of his heel.

An Achilles tendon attached to the heel and calf (Soleus).
Figure 1: This shows the lower half of a human’s leg, where the Achilles tendon is attached to both the heel and calf (Soleus). Modified from Wikimedia Commons.

According to “The Achilles tendon: fundamental properties and mechanisms governing healing” by Freedman et al, the Achilles tendon is the strongest and largest tendon in the entire body, and can bear up to 3500N, or almost 800lb, before completely rupturing. This is a result of the materials that the Achilles is made of. The tendon is 90% collagen, which forms a structure full of fibers that are bound together by other molecules. The tendon is 2% elastin, which like the name suggests, adds some elastic, or stretchy, properties. The tendon is sometimes characterized as a viscoelastic material, meaning it has both viscous (slow to deform) and elastic properties. However, the Achilles is mostly elastic, allowing it to bear relatively high impacts and loads.

Healing the Heel

The Achilles, much like other tendons and ligaments, has interesting healing characteristics and procedures. There are two common recoveries for a tear in the Achilles: a surgery that stitches the ends of the tears together followed by rehabilitation, or a period of rest followed by rehabilitation. For a full tear, surgery is very common, as the torn tendon ends are not always spatially close enough for natural healing processes to occur. For a partial tear, a doctor in consultation with the patient will decide which of the two options will be best.

Experimental Excitement

While there is much more to study with regards to Achilles tear recovery, there is a lot of exciting research being performed on animal models. One study shows that stretching and compressing the Achilles at certain angles during recovery may lead to better long term health of the Achilles. Another study shows the efficacy of stem cell therapies. A third study shows the usefulness of incorporating a 3D printed structure to integrate the ends of torn Achilles. Essentially, this would connect each end with a scaffold that allows for the reintegration of the tendon. This is very similar to an experimental ACL reconstruction technique called BEAR. A video about BEAR can be seen below.

Although John Wall’s career may be in doubt, the future for effective therapies in treating Achilles related injuries is promising. This is exciting for the future, and hopefully will make for a better patient experience. To read more about the Achilles, click here or here.