The following is a great explanation on how running shoes can have a detrimental effect on our feet and lower extremity. This is an excerpt from Daniel Lieberman’s book, “The Story of the Human Body” where he discusses how shoe gear has changed the way most people now walk and run. Daniel Lieberman is a Harvard professor who is know for the groundbreaking article on how transient impacts are seen in shod runners and are absent in those who run barefoot which may help explain the increased incidence of running injuries in those running in heavily padded shoes. If you haven’t read this book, I suggest you do!!
The Story of the Human Body: Evolution, Health, and Disease by Lieberman, Daniel Published by Pantheon 1st (first) edition (2013) Hardcover
Excerpt From: Daniel Lieberman. “The Story of the Human Body.” iBooks. https://itunes.apple.com/WebObjects/MZStore.woa/wa/viewBook?id=97FA485BBB059BEF3D12DA83608FF0A3
What habitually barefoot people know, however, is that you don’t need a shoe with a cushioned heel pad to avoid discomfort when walking and running on hard surfaces. When walking barefoot, one tends to land more gently on the heel, lessening the impact peak, and when running, you can actually avoid any impact peak at all if you land on the ball of the foot before bringing down the heel, in what is known as a forefoot strike.9 You can demonstrate this yourself by simply jumping barefoot (go ahead, do it right now). I’ll bet you naturally first touch down on the balls of your feet before your heels come down, making the landing soft, gentle, and quiet. However, if you forced yourself to land first on your heels, the impact would be loud, hard, and painful (be careful if you try it). The same principle applies to running, which is really just jumping from one leg to the other. By landing gently on the forefoot or sometimes on the midfoot you can run fast on hard surfaces without any cushioning because you don’t generate any noticeable impact peak—as far as your foot is concerned, the landing is collision free. Since pain is an adaptation to avoid harmful behaviors, it should hardly be surprising that many experienced barefoot or minimally shod runners tend to forefoot or midfoot strike when running long distances on hard or uneven surfaces, and many habitually shod runners who usually heel strike switch to a forefoot strike when asked to run barefoot on a hard surface.10 To be sure, some barefoot people land on their heels, especially when going slow, for short distances, or on soft surfaces, but they don’t have to run this way if it becomes painful.11 Many of the world’s best and fastest runners forefoot strike even when they are wearing shoes.
To be clear, I am not arguing that it is unnatural or wrong to heel strike. On the contrary, there are several reasons why barefoot and shod people sometimes prefer to heel strike, especially on soft surfaces. Heel striking allows you to lengthen your stride easily, and it requires much less strength in your calf muscles (which have to contract forcefully while they lengthen to help bring down your heel gently when you forefoot strike). Heel striking is also easier on the Achilles tendon. The thick heels on many shoes also make it difficult not to heel strike. My point is that when you heel strike in a cushioned shoe, your body no longer gets the sensory feedback it expects to help modulate your gait to change the impact. As a result, if you run in cushioned shoes with poor form, it is easy to be a thumper, hitting the ground hard with every step.12 Thanks to the shoe’s cushioned heel, these impact peaks don’t hurt. But if you run 40 kilometers (25 miles) a week this way, each leg experiences about a million forceful impacts per year. These impacts, in turn, may be damaging. Studies by Irene Davis and others have shown that runners who generate higher, more rapid impact peaks are significantly more likely to accumulate repetitive stress injuries in their feet, shins, knees, and lower back.13 My students and I found that members of the Harvard cross country team who heel strike are injured more than twice as frequently as those who forefoot strike.14 The bottom line is that whether you forefoot strike or heel strike, you should do so gently, and being barefoot gives you less choice.
“Shoes have other features designed to increase comfort that also affect your body. Many shoes, including running shoes, have an arch support, which props up the arch of the foot. A normal foot arch looks like a half dome and naturally flattens a little when you walk, stretching to help stiffen the foot and transfer your weight to the ball of the big toe. When you run, the arch collapses much more, acting like a giant spring that stores and releases energy, helping push you into the air (see chapter 4). Your foot has about a dozen ligaments and four layers of muscles that hold the arch’s bones together. Just as a neck brace relieves your neck muscles from supporting your head, an arch support in your shoe relieves the foot’s ligaments and muscles from having to hold up the arch. Arch supports are therefore built into many shoes because they lessen how much work the foot’s muscles have to do. Another labor-saving feature is a stiff sole, which allows the foot’s muscles to work less hard to push your body forward and upward (this is why walking on a sandy beach can tire your feet). Most shoes also have a sole that curves upward toward the front. This curvature, called a toe spring, requires less muscular effort when your toes push off at the end of stance.
Arch supports and stiff, curved soles are unquestionably comfortable, but they can lead to several problems. One of the most common is flat feet, which occurs when the foot’s arch either doesn’t develop or it collapses permanently. About 25 percent of Americans have flat feet15 and thus are more likely to suffer from discomfort and sometimes injury, because a fallen arch changes the way the foot works, causing improper movements in the ankle, knee, and even the hips. Some people’s genes may predispose them to getting flat feet, but the problem is mostly caused by weak foot muscles, which otherwise help create and maintain the shape of the arch. Studies that compare habitually barefoot and shod people have found that barefoot people almost never have flat feet but instead have much more consistently shaped arches, neither low nor high.16 I have examined vast numbers of feet, and I have almost never seen a flat arch in any habitually barefoot person, reinforcing my belief that flat feet are an evolutionary mismatch.
Another related and common problem that may occur from wearing shoes is plantar fasciitis. Have you had a sharp, searing pain in the bottom of your foot either when you get up in the morning or after a run? This pain comes from inflammation of the plantar fascia, a tendonlike sheet of tissue at the base of your foot, which works in conjunction with your muscles to stiffen the arch. Plantar fasciitis has multiple causes, but one way it develops is when the muscles of the foot’s arch become weak and the fascia has to compensate for these weak muscles that are unable to maintain the arch. The fascia is not well designed for this much stress and becomes painfully inflamed.17
When your feet hurt, your whole body hurts, so most people with foot pain are desperate for treatment. Unfortunately, we too often help these unhappy souls by relieving their symptoms rather than remedying the causes of their problems. Strong, flexible feet are healthy feet, but instead of strengthening their patients’ feet, many podiatrists prescribe orthotics and advise patients to wear comfortable shoes with arch supports and stiff soles. These treatments do effectively relieve the symptoms of flat feet and plantar fasciitis, but if their use is not discontinued they can create a pernicious feedback loop because they don’t prevent the problem from occurring and instead eventually allow the muscles of the foot to become even weaker. Consequently, people who wear orthotics become increasingly reliant on them. In this regard, perhaps we should treat the foot more like other parts of the body. If you sprain or damage your neck or shoulder, you might use a brace to relieve the pain temporarily, but doctors rarely prescribe permanent braces. Instead you discontinue using the brace as soon as possible and often have physical therapy to regain your strength.
Since the forces that cause repetitive injuries result from the way your body moves, another underused form of prevention and treatment is to look at how people actually move when they walk and run and how well their muscles can control these movements. Although some doctors will examine the gait of a patient who suffers from a repetitive stress injury, too many just treat the symptoms of the problem by prescribing medications, orthotics, or cushioned shoes. Several studies have found that prescriptions of motion-control shoes, which limit how much the foot rolls in (pronation) or out (supination), have no effect on reducing injury rates among runners.18 Another study found that runners are actually more likely to be injured in more expensive, cushioned shoes.19 Sadly, between 20 percent and 70 percent of runners incur repetitive stress injuries every year, and there is no evidence that the rates have declined as shoe technology has become more sophisticated over the last thirty years.20
Other aspects of shoes also lead to mismatches. How often do you wear uncomfortable shoes because they look good? Millions, maybe even billions of people wear shoes with narrow toe boxes or high heels. Such shoes may be stylish, but they are unhealthy. Narrow toe boxes unnaturally scrunch the front of the foot and contribute to common problems such as bunions, misaligned toes, and hammertoes.21 High heels show off a person’s calves, but they disrupt normal posture, permanently shorten the calf muscles, and subject the ball of the foot, the arch, and even the knee to abnormal forces that cause injury.22 Encasing feet all day in leather or plastic is commonly considered hygienic but actually creates a sweaty, warm, oxygen-free environment that is heaven for many funguses and bacteria that cause irritating infections, such as athlete’s foot.23
In short, many people suffer from foot problems because our feet evolved to be bare. Minimal shoes have been around for many thousands of years, yet some modern shoes designed for a combination of comfort and style can interfere substantially with the foot’s natural functions. I suspect that we don’t need to abandon shoes entirely, and a growing number of shod consumers are responding to these mismatches by wearing minimal shoes that lack heels, stiff soles, arch supports, and narrow toe boxes. It will be interesting to see if they fare any better, and we urgently need to understand how to adapt people with weak feet to the greater muscular demands of wearing minimal shoes. I also suspect it is healthy to encourage infants and children to go barefoot and to ensure that children’s shoes are minimal so their feet develop properly and become strong. Sadly, however, most people today with unhappy feet respond by treating the symptoms of their foot pain with orthotics, ever more comfortable shoes, surgery, medications, and a host of other products available in your local pharmacy’s extensive foot care section. As long as we continue to encase our feet in comfortable, apparently normal shoes podiatrists and others who care for aching modern feet will continue to be very busy.
10. Nigg, B. M. (2010). Biomechanics of Sports Shoes. Calgary: Topline Printing.
11. Variation is always present, and while many experienced barefoot runners prefer to forefoot strike, some habitually barefoot people do sometimes land on their heels. We don’t yet know how much this variation is affected by factors such as skill, distance run, surface hardness, speed, and fatigue. Although habitually barefoot runners from the Kalenjin tribe in Kenya, famous long-distance runners, typically forefoot strike when barefoot, one study of barefoot people from northern Kenya, the Daasenach, found they land often on their heels, especially when going slowly. The Daasenach, however, are pastoralists who live in a hot, sandy desert and don’t run very much. See Lieberman, D. E., et al. (2010). Foot strike patterns and collision forces in habitually barefoot versus shod runners. Nature 463: 531–35; Hatala, K. G., et al. (2013). Variation in foot strike patterns during running among habitually barefoot populations. PLoS One 8: e52548.
12. My personal opinion is that running well for long distances is a skill, just like other athletic skills such as swimming, throwing, or climbing, and that there is much to learn from the way experienced barefoot runners move. More research is needed, but many coaches and experts believe that good running form generally involves landing gently on a nearly flat foot, having short strides, in which the foot lands below the knee, using a high cadence of about 170–180 steps per minute, and not leaning too much at the hips. An important consideration, however, is that this style of running requires more strength in your feet and calf muscles. In addition, if you haven’t run this way before, it is crucial to transition slowly and carefully to build up muscle strength and adapt your tendons, ligaments, and bones. Otherwise, you risk injury.
13. Milner, C. E., et al. (2006). Biomechanical factors associated with tibial stress fracture in female runners. Medicine and Science in Sports and Exercise 38: 323–28; Pohl, M. B., J. Hamill, and I. S. Davis (2009). Biomechanical and anatomic factors associated with a history of plantar fasciitis in female runners. Clinical Journal of Sports Medicine 19: 372–76. For a contrary hypothesis that impact peaks are not injurious because your body dampens the forces, see Nigg, B. M. (2010). Biomechanics of Sports Shoes. Calgary: Topline Printing.
14. Daoud, A. I., et al. (2012). Foot strike and injury rates in endurance runners: A Retrospective Study. Medicine and Science in Sports and Exercise 44: 1325–44.
15. Dunn, J. E., et al. (2004). Prevalence of foot and ankle conditions in a multiethnic community sample of older adults. American Journal of Epidemiology 159: 491–98.
16. Rao, U. B., and B. Joseph (1992). The influence of footwear on the prevalence of flat foot: A survey of 2300 children. Journal of Bone and Joint Surgery 74: 525–27; D’Août, K., et al. (2009). The effects of habitual footwear use: Foot shape and function in native barefoot walkers. Footwear Science 1: 81–94.
17. Chandler, T. J., and W. B. Kibler (1993). A biomechanical approach to the prevention, treatment and rehabilitation of plantar fasciitis. Sports Medicine 15: 344–52.
18. See Ryan, M. B., et al. (2011). The effect of three different levels of footwear stability on pain outcomes in women runners: A randomised control trial. British Journal of Sports Medicine 45: 715–21; Richards, C. E., P. J. Magin, and R. Callister (2009). Is your prescription of distance running shoes evidence-based? British Journal of Sports Medicine 43: 159–62; Knapick, J. J., et al. (2010). Injury reduction effectiveness of assigning running shoes based on plantar shape in Marine Corps basic training. American Journal of Sports Medicine 36: 1469–75.
19. Marti, B., et al. (1988). On the epidemiology of running injuries: The 1984 Bern Grand-Prix Study. American Journal of Sports Medicine 16: 285–94.
20. van Gent, R. M., et al. (2007). Incidence and determinants of lower extremity running injuries in long distance runners: A systematic review. British Journal of Sports Medicine 41: 469–80.
21. Nguyen, U. S., et al. (2010). Factors associated with hallux valgus in a population-based study of older women and men: The MOBILIZE Boston Study. Osteoarthritis Cartilage 18: 41–46; Goud, A., et al. (2011). Women’s musculoskeletal foot conditions exacerbated by shoe wear: An imaging perspective. American Journal of Orthopedics 40: 183–91.
22. Kerrigan, D. C., et al. (2005). Moderate-heeled shoes and knee joint torques relevant to the development and progression of knee osteoarthritis. Archives of Physical Medicine and Rehabilitation 86: 871-75.
23. Also, where did we get the idea that shoes are less dirty than feet? How often do you clean your shoes compared to your feet? For a review of these and other issues, see Howell, L. D. (2010). The Barefoot Book. Alameda, CA: Hunter House.