Health Matters: Skin has vital functions

Conway McLean, DPM, Journal columnist

Current events being what they are, solitary activities have become popular. With an increasing recognition of the importance of fitness, running for exercise has experienced new popularity, at least in part because of the pandemic. It’s a solo activity and it gets you out of the house. But how best to pursue a running program? One trend which had its “day in the sun” is that of barefoot running, or its derivative, the use of minimalist shoes. Is this a healthy running technique, and what are the ramifications to one’s fitness?

Numerous articles have been written about the mechanics of running barefoot but little has been discussed in the media concerning the dangers to skin. The world most of us live in is a concrete jungle, miles of pavement, sidewalks of cement, debris and broken glass. Even in more rural areas, finding healthy running surfaces is challenging. Any type of weight bearing activity, be it walking, jogging, whatever it may be (skipping?), entails tremendous physical stresses to your feet. Shoes are important in reducing pressure to the skin, as well as shear forces, which is different than simple, direct force.

The barefoot craze started primarily because of a book called “Born to Run”, written about an Indian tribe in Mexico, the Tarahumara’s, whose members compete in races of 100 miles or more in flat sandals and rarely suffer running injuries. But how many of us have the chance to run on dry, hard-packed, sandy trails? Cement is not a forgiving surface and broken glass can be found in every town’s streets. Running without sufficient protection can lead to all manner of cutaneous injury.

Skin has many important functions, many of which go unrecognized and unappreciated by your average citizen. For example, did you know our skin is vital to regulating body temperature through its ability to sweat. Also important, our skin acts as a reservoir for vitamin D, a substance essential for health.

Our integument provides vital protection against all the organisms that are part of our world. We are also spared from absorption of all the detritus and debris in the world. Skin protects the body from the physical insult occurring when we do things like walking. Skin also helps to maintain the fluid balance in the body. It serves as the primary barrier to water loss of the body’s water stores. Burns are often fatal for exactly that reason: excess fluid loss leads to shock (a predictable outcome without a largely intact skin layer).

Skin has sensory structures that allows information about the outside environment to be sent to the brain, another critical benefit of a viable skin layer. It does this through the action of an extensive network of nerve cells. Many kinds of nerves exist, with some detecting heat, and others detecting vibration, different one’s sharp, and so on. Stepping on a tack SHOULD hurt! Those individuals suffering from neuropathy are at a real disadvantage. They often won’t know when an injury has occurred and the result is often a failure to treat, or treatment too late. It seems to be difficult to take some problem seriously when it doesn’t hurt.

Our skin is subjected to all manner of insult and injury. It is able to adapt to areas of increased physical stress by thickening, more commonly referred to as callusing. These formations provide some protection against irritation or pressure. But a callus can only do so much, and often results in more pain by increasing the pressure on the living structures beneath the callus. But calluses are a natural and normal result of pressure to some area of skin, a common occurrence on certain areas of the foot.

The skin is an amazing organ, comprising fifteen percent of body weight. Between skin and the various skin structures, primarily nails and hair, it is the largest organ in the body. The thickness of skin varies greatly, from the skin of the eyelid, which is less than 0.1 mm, to that of the bottom of the feet, the thickest anywhere on the body (1.5 mm).

The skin on the bottom of the feet has two extra layers not found anywhere else. The stress it must endure is tremendous, especially when foot alignment is abnormal, what might be called bad foot architecture. Any protruding bone or bent toe can lead to excessive skin pressure, and the resulting painful callus. This is a common situation, as evidenced by the number of products devoted to calluses in the foot section at the pharmacy.

Especially troublesome is the individual who has neuropathy and has, or develops, improper bone architecture causing a callus on the bottom of the foot. They often walk on the inflamed area of skin without pain. Too often an ulceration results, considered the seminal event “on the stairway to amputation”. Custom-fit shoes and innersoles are vitally important to this patient population, which explains the importance of the Medicare Diabetic Shoe Program, a real life-saver.

Numerous deformities, some incredibly common, result in skin pressure. How quickly calluses form is due to the interplay of many factors. Genetics is naturally one of the most consequential. One may genetically form calluses faster or easier than most people. But some inherit a foot type which causes the formation of hammertoes. These can press down on a metatarsal bone, pushing it down into the ground (often an unforgiving surface).

The most obvious treatment is to remove the extra skin in the area of (hopefully) pain. The sales of implements intended to remove callused skin are a booming business. Unfortunately, this is a poor solution since, with continued pressure, callus production g speeds up over time. The skin learns to make it faster and faster. More effective is the removal of the source of the pressure. This is another area in which custom foot orthoses (aka orthotics) excel. When properly fashioned and fitted, they effectively de-weight the symptomatic region, producing relief and healing.

Some abnormalities aren’t amenable to orthotic therapy but need to be treated surgically. Although many people continue to have outdated ideas about the pain and difficulties of foot surgery, newer techniques and technologies, especially minimally invasive surgery, have made it a reliable, comfortable process. Certainly, padding of the prominent area is used by many, and it has its fans, but works best when some flare-up of pain develops, perhaps after some strenuous activity. Otherwise it has to be part of your daily ritual, performed day after day, ad nauseum, or else suffer.

The complexity of our skin, its many functions and processes, continues to astound. It is unfortunate that the skin so essential to quality of life, that on the bottom of the feet, is so easily ignored. Out of mind, out of sight, hidden away, not seeing the light! Moisturize, wear appropriate shoes for your foot type and activity. Keep a watchful eye on the skin there, including each surface, every toe. It has a difficult, vitally important role in our health. Take care of your skin, it’s the only one you’re in.

Editor’s note: Dr. Conway McLean is a physician practicing foot and ankle medicine in the Upper Peninsula, with a move of his Marquette office to the downtown area. McLean has lectured internationally on wound care and surgery, being double board certified in surgery, and also in wound care. He has a sub-specialty in foot-ankle orthotics. Dr. McLean welcomes questions or comments atdrcmclean@outlook.com.


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