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Preventive Foot Health

This paper provides a comprehensive overview of preventive foot health – the origin of the preventive foot health concept; the key tenets of the practice of preventive foot health; information on how the feet function and how they incur damage with age and activity; and the magnitude of foot health issues in the United States today.


The Institute for Preventive Foot Health has recognized the nature of long-term degradation of the human foot in industrialized society. It also recognizes that there are multiple contexts for "prevention," and in fact it has identified three contexts for prevention as it relates to the human foot. These are:

Prevention of originating foot issues. This context addresses the healthy foot and aims at prevention of those states or events that will lead to injury in the healthy, viable foot.

Therapeutic intervention for those foot issues where there is an existing physical, biomechanical or systemic condition that is causing or exacerbating a possible debilitating foot issue.

Prevention of the recurrence of foot issues as the logical continuation of therapeutic interventions, with the goal of ensuring future mobility.

The Institute further recognizes three primary states of the foot that have a bearing on both the nature and the duration of preventive or therapeutic measures. These states are: (1) The healthy foot - a viable, non-compromised foot characterized by the absence of physical and morphological abnormalities, as well as the presence of a healthy vascular state; (2) the compromised foot - a foot that has the beginnings of, or a non-advanced case of a systemic ailment or physical anomaly that causes concern for the long-term health of the foot; and (3) the at-risk foot - the foot that is at risk of ulceration, amputation or serious damage if physical and/or systemic issues are not addressed in an urgent manner.


"Preventive Foot Health" is defined as the practice of taking proactive measures to protect and care for the feet to reduce the probability of incurring serious problems as the feet age over the course of a person's lifetime. Preventive foot health is necessary in all sports and activities as well as in daily work and home routines. It is a vital and critically important practice in persons with chronic health problems such as diabetes, arthritis, and circulatory disease where small problems can be magnified into both limb and life threatening conditions.

The Institute for Preventive Foot Health (IPFH)

The Institute for Preventive Foot Health is a non-profit private foundation founded in 2002 by James L. Throneburg, the owner of THOR·LO, Inc., the world's leading brand of activity-specific protective sock products. Its purposes are to promote awareness of the need for the practice of preventive foot health as a key to a sustainable quality of human life, to promote research and education dedicated to the development of preventive foot health practices and products, and to support other organizations and associations which demonstrate dedicated efforts toward the awareness, application and practice of preventive health. The unique contribution for the IPFH envisioned by Mr. Throneburg arises from the serious lack of awareness of proper preventive foot health practices among the general population (and even significant parts of the medical community), the reality that the human foot in industrialized societies undergoes a process of continual degradation over the course of a lifetime that can now be effectively addressed by application of preventive foot health practices and products, and most importantly, the recognition and acceptance of the fact that the quality of human life is directly related to people's ability to walk in comfort and without pain.

The Origin of the Concept of Preventive Foot Health

The concept of preventive foot health originated with various scientific and medical research conducted with sock products designed and manufactured by THOR·LO. Several years after THOR·LO introduced its sport and activity specific sock products in 1980, there started to accumulate significant and consistent anecdotal evidence from consumers and physicians that indicated that the high density padded sock products had a beneficial effect on foot problems experienced by many people. THOR·LO's owner, James L. Throneburg, was curious as to why this might be the case, and decided to sponsor a series of clinical research studies to help determine scientifically the reason for the products' efficacy. In October of 1989, the first study was published in Diabetes Care, a peer-review journal published by the American Diabetes Association. The study was completed with a population of diabetic patients, and demonstrated that the high density padded sock products provided significant reduction of pressure in the insensitive, at-risk diabetic foot. Over the course of the next seven years, seven more studies were conducted that further demonstrated the pressure reduction benefits of the sock products, as well as benefits in blister reduction, in forefoot impact reduction, in reduction of pain in the rheumatoid arthritic foot, and in the enhancement of lower limb circulation in people with mild to moderate venous insufficiency. Taken as a body of evidence, these studies, along with a continuing stream of correspondence from consumers and physicians, clearly demonstrate both the preventive and therapeutic efficacy of anatomically-designed high density padded sock products, combined with properly fitted shoes in addressing the static and dynamic forces of pressure, impact and shear that underlie nearly all foot problems.1

The Practice of Preventive Foot Health

Preventive foot health has been defined by IPFH as the practice of taking proactive measures to protect and care for the feet to reduce the probability of incurring serious problems as the feet age over the course of a person's lifetime. Consistent with this definition, an understanding and awareness of the root causes of foot problems, the value of effectively designed, constructed and fitted sock products and properly fitted shoes, and the knowledge of proper foot care provide the foundation for the concept of preventive foot health. Specifically, preventive foot health encompasses the following areas:

  • Individual awareness of effective preventive foot health practices in the areas of proper sock product and shoe selection and fitting, biomechanical functionality, skin management, nail care and general hygiene practices related to the feet;
  • Institutional and organizational awareness of both the quality of life and significant economic benefits to individuals and society of the practice of preventive foot health;
  • Conscious design of practices and products that function in an integral manner to promote a healthy, natural gait during all activities and sports;
  • Establishment and certification of preventive foot care as a key discipline within the medical profession, particularly the nursing profession, as a means of providing effective preventive, as well as, therapeutic care for the feet.
  • Endorsement and sponsorship of scientific research that enhances and elaborates the theory, practice and benefits of preventive foot health;
  • Public awareness and education regarding condition-specific and disease-specific foot care practices (i.e. diabetes and other conditions that have a substantial impact on foot health);
  • Public awareness and promotion of preventive foot health as a required foundational competency, in the current health care environment, for an overall approach to well being, in conjunction with sound exercise practices and proper nutrition.


The need for preventive foot health and its value to individuals is not recognized among the general populace. Because feet are the extremities farthest from the mind (both literally as well as figuratively), people tend to give them little thought - at least until they become painful. In the industrialized world, most people tend not to have any significant foot pain until they reach their middle 30's (and on into their 40's).2 By the time a person has reached his or her 50's, especially if he or she has led an active life, half of the feet's plantar fat padding may have been lost.3 In fact, deterioration of the fat padding tends to accelerate after the mid-40's, at which point most people have walked about 75,000 miles on their feet.4 The loss of fat padding contributes to serious as well as more mundane foot pain and problems; but in addition to the loss of fat padding, from about the middle 30's and on, the muscles of the feet weaken, and the tendons and ligaments grow less resilient.5 Thus, it is not surprising that there are widespread foot problems among people of all ages, but especially among those of age 40 and above. In fact, an estimated 90 million adult Americans say that their feet hurt them much of the time.6 The good news is that both peer reviewed medical research over a period of 15 years, and more than 20 years of anecdotal evidence developed at THOR·LO show that preventive foot health practices and products can and do relieve and/or eliminate the pain caused by this fat pad deterioration. The next frontier of medical research being funded by IPFH will, for the first time in a peer reviewed scientific study, determine the level of deterioration of the fat padding as people age, and will subsequently go on to test the hypothesis that this deterioration can be mitigated or even stopped by preventive foot health practices and products.

How the Feet Work

The human foot evolved into an organ to support humans in the upright position during bipedal ambulation. This evolution, however, occurred to support man on natural surfaces (grass, dirt, sand, gravel, etc.), not on the man-made, artificial surfaces on which most people in the industrialized world walk today (concrete, asphalt, and the hard floors of the buildings in which we live and work). The foot works in such a way that, during normal walking gait, it performs the function of shock absorber (during heel impact), and then in milli-seconds, transforms itself into a rigid lever (during toe-off) that propels the body forward. The feet repeat this function millions of times during the course of a person's life, carrying him or her an average distance of 150,000 miles.7

In normal barefoot ambulation on natural surfaces, the shock absorbing capacity of the bones and joints of the foot are complemented by the thick plantar skin on the bottom of the foot and the plantar fat pads between the bones and the outer layer of skin. These help cushion the foot and the entire body from normal impact on natural surfaces during walking and running. Each foot is aided in its natural state by the presence of approximately 125,000 sweat glands, which have been proven to be stimulated not so much by thermal factors, but by emotional stimulation (what is known as the "fight or flight" response).8 The secretion of sweat in the feet is meant to serve the same purpose as that in the hands - more friction for greater tactile facility. In the case of the feet, it is for the purpose of the foot's ability to more easily "grip" the ground in the barefoot state, not for the purpose of cooling that is normally associated with perspiration in other parts of the body (during strenuous activities sweat continues to be secreted irrespective of the temperature of the foot). In the natural barefoot state, this moisture dissipates easily in the air or is left on the contact surfaces; but inside a shoe it accumulates and exacerbates damaging forces on the feet.

In the barefoot state on natural surfaces, there are five forces that act on the foot: (1) vertical impact, (2) torque, (3) fore and aft shear, (4) lateral shear, and (5) pressure. In this state, impact and pressure forces are dissipated by the plantar fat pads and the skeletal system working together. Torque and shear are dissipated by the plantar fat pads, the plantar skin and the yielding natural surface working in concert with one another. During normal walking and running in today's footwear, considerable shear forces develop between the outer skin of the foot, the supportive surface of the shoe (i.e. the footbed) and the bones of the foot lying on top of the plantar fat pad itself. Shear develops when the metatarsal bones "glide" across the plantar fat pad that is "trapped" between the bones and the fixed plantar skin, which in turn is adhered to the supportive surface. As the bones glide forward across the natural plantar padding, the "adhered" outer plantar skin and the supportive surface are moving in the opposite direction, and trauma occurs to the plantar fat pad and skin. Faulty biomechanics, where hyper mobility of the forefoot occurs, further result in unnecessary migration of the metatarsals across the plantar pads and skin. This hyper mobility of the foot, coupled with the normal forces of ambulation, results in abnormal shearing forces of the metatarsals against the padding and skin of the foot. Breakdown of tissue results from impact, friction, and shear. This results in thickening of the plantar skin and inflammation of the deeper padding tissues. Inevitably, over time, repeated vertical and horizontal shearing forces on the subcutaneous tissues of the foot result in atrophy of the plantar fat pad and ultimate loss of natural cushioning.

Shearing is minimized in the natural barefoot state when the human foot walks on natural surfaces. These surfaces - i.e., grass, dirt, sand and gravel - have the ability to dissipate forces in both the vertical and horizontal planes. That is, as the human foot impacts and propels off of these natural surfaces, the surface itself gives way in both the vertical and horizontal planes. A movement interface occurs within the supportive surface itself. Movement does not occur between fixed plantar pad and skin and the metatarsal bones. Rather, the foot rests on the supportive natural surface; and the natural surface glides and yields beneath the foot, minimizing the damaging forces. 9

Root Causes of Foot Problems

As humans became more "civilized," we proliferated more artificial surfaces (asphalt, brick, concrete, and hard flooring). In the modern environment, we have no choice but to walk, run and play on these surfaces (except, perhaps, the rare opportunities when we are able to walk barefoot in sand at the beach, or to play barefoot in the grass). To protect our feet from this "unfriendly" environment, we developed shoes. Ironically, chronic foot issues in today's industrialized society are widespread - primarily the result of walking on smooth, unyielding man-made surfaces - and are compounded by poorly designed and ill-fitted shoes that we wear to "protect" ourselves from these surfaces. The characteristics of the smooth, unyielding surfaces severely compromise the natural function of the human foot. The smooth, unyielding quality of man-made surfaces precludes the foot's ability to dissipate vertical, horizontal and oblique forces. This ability is even more severely inhibited when the human foot is placed in a shoe, which then moves on the man-made surface. The net result is that a friction or movement interface is set up between the bones and fatty pads of the foot and the outer skin of the foot. No movement occurs within the supportive surface, and no movement occurs within the shoe itself. Only the foot can then bear the brunt of the shearing forces. The cumulative effect of these shearing forces causes the breakdown and disability of the foot tissues.

The smooth, unyielding man-made surfaces also completely negate the natural "peripheral pump" mechanism operating between the feet and the legs, which assists blood flow from the feet and legs back to the heart. The peripheral pump relies on a natural "milking" action of the leg muscles to contract against the veins and push the blood (against gravity) back toward the heart. These muscles are stimulated each time the foot steps on a natural yielding surface. The natural surface allows the foot to sink into it with some slight movement or rotation during the sinking motion. This in turn stimulates leg muscle action and results in activation of the peripheral pump. Smooth, unyielding surfaces do not allow the normal muscular contractions to occur. The foot cannot mold or adapt to the man-made surfaces as it does with natural, "forgiving" surfaces. Thus, little or no muscular stimulation occurs. A frequent result is the accumulation of fluid in the feet and lower legs. This fluid accumulation results in chronic ankle edema, varicose veins, skin necrosis, and general foot and leg fatigue.10

In addition to all of the foregoing damaging forces, the moisture generated by the feet inside the shoes, if not evacuated, accumulates and causes adherence of the feet to the surface(s) inside the shoes, compounding the damage.

While the original intent of shoes was to provide protection for the feet, in reality today they are primarily fashion statements, and even at their best, suboptimal solutions to foot problems. William A. Rossi, a noted Doctor of Podiatric Medicine said, "It took four million years to develop our unique human foot and our consequent distinctive form of gait, a remarkable feat of bioengineering. Yet, in only a few thousand years, and with one carelessly designed instrument, our shoes, we have warped the pure anatomical form of human gait, obstructing its engineering efficiency, afflicting it with strains and stresses and denying it its natural grace of form and ease of movement head to foot. We have converted a beautiful thoroughbred into a plodding plow horse."11

The Magnitude of Foot Issues in the Industrialized World

The frequency and persistence of foot issues today is astounding. According to the American Podiatric Medical Association (APMA), there are more than 55 million visits a year to podiatrists nationwide. APMA also notes the following: about 19% of the U.S. population (53.4 million people based on the 2000 Census) have an average of 1.4 foot problems each year; about 5% of the U.S. population (14 million people) have corns or calluses each year; about 6% (17 million people) of the U.S. population have foot injuries, bunions, flat feet or fallen arches each year.12 According to the Centers for Disease Control, in 1997 13.25 million people could not walk a quarter of a mile, and 15.7 million people could not stand on their feet for two hours. According to the American Academy of Orthopaedic Surgeons (AAOS), foot problems account for $3.5 billion per year in medical costs and lost time from work (this number is probably substantially understated, since it includes only cases where actual surgery is necessary). There is also a direct link between the current epidemic of obesity (and its emergent related issues of coronary heart disease and diabetes) and foot health: "Body weight plus intensity of impact equal the force that causes true wear and tear on the feet. That's one reason why adults tend to decrease their level of activity - sometimes without even realizing what they're doing - as they gain weight. With a 20 pound weight gain, we put 30 extra pounds of pressure on our feet even when we're only walking at a slow pace. Running transforms that 20 pounds into 60 - and dozens of bones, joints, ligaments and muscles must support the added impact. Bearing this mathematical formula in mind, it's easy to understand why so many overweight people become discouraged and give up on exercise."13 Poor foot health and mobility is thus a critical contributor to the obesity epidemic facing the industrialized world today.

The Critical Need for Preventive Foot Health NOW

As already noted, foot issues are responsible for a more than $3.5 billion burden on the U.S. healthcare system; and the burden is just as heavy in other industrialized countries. The long-term degradation of the feet over the course of an individual's lifetime has a negative impact on his or her quality of life, as well as productivity at work, especially at age 40 and beyond. As the population ages this will increasingly become an issue for our health care systems. Furthermore, poor foot health is an exacerbating factor in the current obesity epidemic facing the industrialized world today. Diseases and conditions that are the result of obesity (primarily diabetes and coronary heart disease) are already taxing our healthcare system and will only become more widespread as the incidence of obesity increases. Exercise and mobility are key to attacking this epidemic of obesity. A population that is not mobile because of foot pain and discomfort cannot, or will not, walk or exercise; therefore, preventive foot health is not just a key to addressing overall health issues, but is a cornerstone of an approach to total health and well-being. The IPFH is dedicated to establishing public awareness of the value of preventive foot health in the health care system, as well as in the realm of individual awareness and practice.


1. The eight peer-reviewed, published studies cited are as follows:

  • "Use of Experimental Padded Hosiery to Reduce Abnormal Foot Pressures in Diabetic Neuropathy" Aritidis Veves, MD; Ewan Masson, MRCP; Devaka Fernando, MRCP; Andrew J.M. Boulton, MD; published in Diabetes Care, vol. 12, No. 9. October, 1989.
  • "Studies of Experimental Hosiery in Diabetic Neuropathic Patients with High Foot Pressures" - Aritidis Veves, MD; Ewan Masson, MRCP; Devaka Fernando, MRCP; Andrew J.M. Boulton, MD; published in Diabetic Medicine, vol. 7, pgs 324-326. January, 1990.
  • "Friction Blisters and Sock Fiber Composition, a Double Blind Study" - Kirk M. Herring, DPM and Douglas H. Richie, Jr., DPM; published in Journal of the American Podiatric Medical Association, Vol. 80 no. 2, February, 1990.
  • "Friction Blisters and Sock Fiber Composition, a Single Blind Study (Part 2)" Authors: Kirk M. Herring, DPM, Douglas H. Richie, Jr. , DPM. Presented at 75th Annual Meeting of the American Podiatric Medical Association, Las Vegas, NV, August, 1990. Also published in the Journal of the American Podiatric Medical Association, Volume 83 number 9 entitled "Comparison of Cotton and Acrylic Socks Using a Generic Cushion Sole Design for Runners" (September, 1993).
  • "The Use of Specially Padded Hosiery in the Painful Rheumatoid Foot" A. Veves, E.M. Hay, A.J.M. Boulton University Departments of Medicine and Rheumatology, Manchester Royal Infirmary, Manchester, UK. 1992. Published: The Foot, no. 1, 175-177, 1992.
  • "Role of Experimental Socks in the Care of the High Risk Diabetic Foot" A multi- center patient evaluation study. Heather J. Murray, DPOD M, Aristidis Veves, M.D.; Matthew J. Young, M.D.; Douglas H. Richie, DPM; A.J.M. Boulton, MD. American Group for the Study of Experimental Hosiery in the Diabetic Foot. Published: Diabetes Care, Vol. 16, no. 8, August, 1993.
  • "The Use of Thorlos Walking and Support Hosiery in the Treatment of Circulation Problems of the Feet and Legs" Authors: Dr. Alice Brown, Pharm D.; Dr. Jack Brown, D.O. Published: Journal of the American Osteopathic Association - March, 1995.
  • "The Effect of Padded Hosiery in Reducing Forefoot Plantar Pressures" Authors: Shawn Flot, MPT; Von Hill, MPT; Wesley Yamada, DPM; Thomas McPoil, PhD, PT, ATC; Mark Cornwall, PHD, PT. Published: The Lower Extremity Vol. 2, No. 3 September, 1995.

2. Macdonald, Ann; Footcare Basics; Harvard Health Publications; 2001, p.5.

3. Ibid.

4. Levine, Suzanne M., DPM; Your Feet Don't Have to Hurt; St. Martin's Press; New York; 2000.

5. Macdonald, Op. Cit.

6. Levine, Op.Cit.

7. Macdonald, Op. Cit.

8. Richie, Douglas H. Jr., DPM; New Treatment Modalities for the Human Foot: The Dawn of a Revolutionary Concept; unpublished paper, 1988.

9. Ibid.

10. Ibid.

11. Rossi, William A., DPM; Why Shoes Make "Normal" Gait Impossible; 1996.

12. American Podiatric Medical Association, Foot Facts, 2004.

13. Levine, Op.Cit.

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