Use of Muscle Strengthening to Treat Plantar Fasciitis

Abstract

Plantar fasciitis is one of the most common causes of pain in the heel and sole of the foot. It affects approximately 10% of the population and accounts for 600,000 outpatient visits annually (9). The plantar fascia is a dense, fibrous tissue spanning the length of the foot. It originates at the medial calcaneal tubercle and attaches to the phalanges. The plantar fascia provides stability and arch support to the foot. Plantar fasciitis is defined as inflammation of this tissue from excess stress, and predisposing factors include overtraining, obesity, pes planus, decreased ankle dorsiflexion, and inappropriate footwear (2,4). Our current society is a civilized culture of supporting feet with shoes, insoles, and even orthotics. Sore feet, a common problem and precursor to plantar fasciitis, are generally treated with rest, stretching, and more support (1,2,4,10,11). Shoes and such supports may lead to atrophy and weakening of the splinted muscles (6,7). Unappreciated in modern medicine, feet have similar intrinsic muscles as hands. Feet have four layers of intrinsic muscles all designed to provide strength and support (5). The plantar intrinsic muscles may be among the most unknown and neglected muscles in the human body. Feet are capable of grabbing things and even writing. People born without upper limbs have been able to live long and fulfilling lives after training themselves to be just as dexterous with their feet as many are with their hands. To maintain hand strength, gripping things will strengthen the muscles. The same can be done with feet. In the 1960 Summer Olympics, Ethiopian marathon runner Abebe Bikila made history when he won the gold medal while running barefoot. Many African marathon runners today still train without shoes (3). In the 1970s, running shoes were thin-soled, and the feet of great runners were very strong. Zola Budd, the women’s 5,000-m world record holder in 1985, trained and raced barefooted. Daniel Lieberman, professor of biological anthropology at Harvard and an avid runner, states “A lot of foot and knee injuries that are currently plaguing us actually are caused by people running with shoes that make our feet weak…” (6). McDougall (7) gathers an impressive array of sources to harshly criticize the running shoe industry for creating shoes that weaken our feet, causing runners to rear-foot strike rather than forefoot/mid-foot strike before bringing down the heel, leading to a more evenly spread force of impact across the foot. He states that the “habitually shod runners” have caused a decline in American running performance that we are only now getting out of (7). Largely because of his book and others, there is an emergence of barefoot and minimalist running shoes that improve performance but require strong feet. Recent research has shown that strength training improves outcomes in patients with plantar fasciitis compared with traditional therapy of stretching and supports (3,8). Pain and inflammation in the plantar fascia could be due to weakness of the intrinsic muscles of the foot adjacent to this fascia. We have had success in treating patients with plantar fasciitis with muscle strengthening and have used a simple exercise, the foot grip, which can be done anywhere and anytime. The patients were prescribed a simple foot muscle exercise, the foot grip (Figure). Patients are instructed to tighten the muscles of the foot as if they were going to pick something up with the bottom of the feet. They hold this contraction for a few seconds and then relax. They are asked to do this 100 times a day, and it can be done in shoes and while standing, sitting, or lying down.Figure: Foot grip exercise.Typically, improvement occurs in 1 to 2 weeks, with resolution of the problem in approximately 4 weeks. One benefit of this muscle strengthening is that the feet become stronger, allowing the person to continue sports. Another benefit is that patients who perform these exercises are much less likely to experience a relapse. Because strong feet would be less likely to get plantar fasciitis, foot grips may play an important role in the prevention of this condition. We are performing an ongoing study on the use of foot grips to treat plantar fasciitis. Other exercises may be helpful as well in preventing and treating plantar fasciitis. These would include tiptoeing and barefoot walking. Wearing thong-type sandals that require gripping also may lead to strong feet. All training should be increased gradually to avoid overuse that may lead to plantar fasciitis muscle and tendon strains. We suggest that promoting stronger feet become a part of patient education in sports medicine.