Foot and ankle exercises in patients with diabetes

By Pamela D. Ritzline, PT, EdD, and Audrey Zucker-Levin, PT, PhD.

Guidelines recommend cardiovascular and strengthening exercises in patients with diabetes, but flexibility exercises focused on the foot and ankle can impart added benefits. Improving range of motion can positively affect gait, pressure distribution, and risk of foot ulceration.

Diabetes mellitus (DM) is a chronic, systemic disorder that disturbs the body’s insulin mechanisms, altering blood glucose levels, which can lead to severe health problems and disability.1 DM is epidemic worldwide with a significant number of people in the United States having this condition. The American Diabetes Association (ADA) reports 23.6 million children and adults in the U.S. have diabetes, with 17.9 million diagnosed, 5.7 million undiagnosed, 57 million in a pre-diabetes state, and 1.6 million new cases diagnosed annually in persons 20 years of age and older (most recent data gathered in 2007). DM is the seventh leading cause of death in the U.S., contributing to 233,619 deaths in 2005 (last year data available). The cost of diabetes care was $174 billion in 2007.2 The number of individuals affected by this disease continues to rise; therefore, holistic care is imperative to control the functional limitations affecting patients with DM.

As the incidence of DM rises, healthcare professionals must recognize the risk factors contributing to the development of the disorder. The list is quite lengthy; however, the common risk factors include obesity, physical inactivity, elevated blood glucose, hypertension (> 140/90), smoking, family history, and abnormal lipid metabolism. The incidence of DM increases with age with men having a slightly greater risk than women, and African Americans having the greatest risk of developing DM.2 The more risk factors a person has, the greater the risk of developing type 2 diabetes and associated medical problems. Associated medical problems include cardiovascular disease, peripheral neuropathy, retinopathy, renal failure, dental disease, erectile dysfunction, ketoacidosis, hyperlipidemia, cognitive impairment, an increased susceptibility to other illnesses such as pneumonia or influenza, decreased range of motion of the feet and ankles, balance impairment, and non healing ulcers that may lead to amputation.2

Exercise and diabetes

The benefits of exercise for the diabetic population are widely described in the literature. Although a detailed discussion of the evidence supporting the need for exercise in persons with type 2 diabetes is beyond the scope of this article, a preponderance of such evidence exists.2-18 A Pubmed/Medline search using the words “diabetes, exercise, training” yielded 2481 citations. Culling through the citations revealed studies with outcomes that supported exercise for improving VO2max anaerobic threshold, time to anaerobic threshold,3 improving endurance,3,4 improving strength,5-8 improving metabolic control,9-12 improving emotional well being,8,9 and improving mental health and vitality8 while decreasing metabolic syndrome risk factors13 decreasing insulin requirement,9,11 and decreasing falls.14,15 Exercise also has been shown to increase the cells’ sensitivity to insulin, improve blood glucose control (decreasing the amount of medications necessary)2 decrease hypertension, improve lipid metabolism leading to a healthier heart, assist with weight control, reduce cardiometabolic risks, improves sleep patterns and energy levels, reduce stress, increase flexibility, and build stronger bones and muscles.2,16-18 No negative effects from exercise were discovered in the citations reviewed.

The extensive literature review revealed that exercise interventions varied in longevity (from one week to a lifetime), in duration (from two to seven days per week), and in intensity. Some interventions focused on cardiovascular fitness, others on muscle strengthening, balance, and/or flexibility. Some programs incorporated multiple interventions. So, which exercises are most beneficial and how do we assure compliance long term?

Five basic categories of exercise are recognized: cardiovascular, strength, flexibility, balance, and cognitive. The U.S. federal government has published Physical Activity Guidelines for all Americans, including those with chronic disease such as diabetes.1 The guidelines clearly state that adults should participate in a total of 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity aerobic physical activity per week. Exercise should be spread over the entire week with sessions divided into 10 minute intervals. The simplest exercise would be to encourage individuals to walk at a vigorous pace while wearing appropriate footwear. Other options involve use of equipment such as a bicycle, elliptical, stepper, or treadmill to accomplish the cardiovascular requirement.1

The guidelines also recommend that adults perform at least twice weekly strengthening exercises of all major muscle groups. People can be instructed in exercises that use bodyweight as resistance or machines for resistance. Major muscle groups include the quadriceps, hamstrings, calves, abdominals, biceps, triceps, and forearms. Guidelines vary on intensity and frequency, with benefits reported from performing one set of 15 moderate intensity repetitions to three sets of 15 repetitions of low intensity repetitions. The frequency and intensity should be tailored based on an individual’s perceived ability to maintain the program.1

In addition to cardiovascular and strengthening exercise, people with DM should participate in a flexibility program. Peripheral neuropathy, as a result of diabetes, may cause sensory and proprioceptive loss in the extremities and decreased range of motion, specifically at the ankles, feet, and shoulders. Zimny et al reported progressive stiffening of collagen containing tissue in people with DM, which may add to joint stiffness.19 This increased joint stiffness results in diminished range of motion, but because the associated clinical disability is often subtle, it is often overlooked.19

Decreased range of motion in the ankle and foot may cause gait abnormalities, such as a footflat contact or a forefoot contact gait pattern. Either pattern eliminates the energy conserving and force attenuating motion that occurs at the ankle and subtalar joint during a normal gait cycle. Further, diminished metatarsophalangeal joint dorsiflexion in the pre-swing phase of gait may result in decreased balance and abnormal forefoot pressure. If MTP joint dorsiflexion is not sufficient, the person may shorten their step length and exert more energy to lift the leg from the support surface because a rigid lever for push-off is not achieved. This gait pattern may increase susceptibility to falls and injury. In addition to balance impairment, joint stiffness throughout the foot may lead to increased midfoot and forefoot pressure when walking. This can increase the risk of ulceration, particularly in patients with peripheral neuropathy.20 This is supported by the findings of Fernando et al, who reported that limitations in subtalar and first metatarsophalangeal joint mobility resulted in increased peak foot pressures during gait.21

Foot and ankle exercises

Goldsmith et al found that persons with DM who were educated in a foot and ankle exercise program experienced decreased joint stiffness and decreased peak plantar pressure during gait after only one month of intervention.22 The regimen included “drawing” the alphabet with the foot (ABCs), passive and active dorsiflexion and plantarflexion of the metatarsophalangeal joint, passive and active dorsiflexion and plantarflexion of the ankles, active pronation and supination of the subtalar joint, stretching of the gastrocnemius and soleus, followed by soft tissue manipulation of the entire foot. Exercise may improve joint stiffness and impact ulcer healing. Flahr evaluated the effect on neuropathic foot wounds of non-weightbearing foot and ankle exercises (including active inversion, eversion, dorsiflexion and plantarflexion) performed 10 times each twice a day, and found that those patients who participated in the exercise program trended toward more rapid healing. Flahr attributed the healing to improved blood supply in the area.23

We performed a randomized, controlled study on the effect of a six-week home exercise program, which focused on range of motion of the first metatarsophalangeal joint and the talocural joint, on gait parameters in persons with type 2 DM.24 Ten subjects participated in a home exercise program (HEP) developed according to the American College of Sports Medicine guidelines. The HEP consisted of a five to 10 minute warm-up walk, ABCs, heel raises, toe raises, and towel exercises (dorsiflexion, eversion, and inversion) to be performed three times per week for six weeks. A difference in plantarflexion ROM was the only significant effect of the exercise program for our population. No significant changes in gait were noted. This may have resulted from the short duration of the program.

Patients diagnosed with DM should be instructed in a home exercise program that focuses on maintaining or improving range of motion in the ankle and foot. Simply “drawing” an exaggerated alphabet with the ankle twice daily; actively performing ankle dorsiflexion, plantarflexion, inversion, eversion 10 times each twice daily; and manually mobilizing the forefoot, including the first metatarsophalangeal joint, into dorsiflexion will help to increase range of motion of the foot, diminish peak foot pressure, and possibly prevent breakdown.

Balance exercises also should be incorporated into the daily exercise regime of someone with diabetes. Wrobel and Najafi25 reported that people with diabetes walk with “a conservative gait strategy” characterized by a wider base of support and prolonged double support time. This gait pattern may be a protective strategy to counter the effects of decreased balance from diminished proprioception. For this reason, daily balance exercises in a protected environment are recommended. Persons with diabetes can be encouraged to maintain their balance by standing on one foot while brushing their teeth or while washing the dishes. Balance activities can be progressed to be more challenging, first by performing dynamic activities such as raising the arms or catching a ball while standing on a wide stable base of support with two feet on the ground, then by performing the same activity with a progressively smaller base of support, such as standing on one foot. Balance activities can be progressed from a stable surface to unstable surfaces such as sand or a dome while diminishing the base of support area.

Cognitive exercise is a relatively new area of study. Van Elderen et al found increased progression of brain atrophy and decreased cognitive function in patients with diabetes compared to normal controls.26 Although data do not exist to support the benefits of cognitive exercise in people with diabetes, initiating a cognitive exercise program may help maintain cognitive function. Spending 30 minutes daily learning a new skill, such as a foreign language or an instrument, or even doing daily crossword puzzles or other brain teasers may help maintain or improve cognitive function in people with diabetes.

Adherence to an exercise program is challenging for any individual, independent of diabetes. Beverly and Wray27 reported that collective support, motivation and responsibility all play a role in empowering an individual to stick with an exercise program.

Lastly, before engaging in any exercise program, patients with diabetes should consult a physician to ensure participation in such activity is safe. Once the patient has been cleared to exercise, a physical therapist can design an individualized program that incorporates the appropriate exercises and focuses on the needs of the patient. Individuals with DM must be cautioned to monitor blood glucose levels before, during, and after exercise to avoid a hypoglycemic event during or after exercise as well as a hyperglycemic event 24 hours post exercise.2,16,17 As health care providers, we must support and encourage exercise in our patients by being role models and advocates.

DM is epidemic in the U.S. Maintaining health through exercise decreases costs and improves quality of life.28 A preponderance of evidence suggests that every person with DM should participate in a consistent exercise program. We, as health care providers, must work together to identify patients in need of guidance and direct them to the appropriate practitioners who understand the potential complications unique to this population.

Pamela D. Ritzline, PT, EdD, is associate professor and director of the graduate program in the department of physical therapy at the University of Tennessee Health Science Center in Memphis. Audrey Zucker-Levin, PT, PhD is an associate professor in the same department.

References:

1. CDC National Diabetes Fact Sheet US, 2005. Available at: http://www.cdc.gov/diabetes/pubs/pdf/ndfs_2005.pdf

2. American Diabetes Association. Diabetes statistics. Available at: http://www.diabetes.org/diabetes-basics/diabetes-statistics/

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20. Sacco IC, Hamamoto AN, Gomes AA, et al. Role of ankle mobility in foot rollover during gait in individuals with diabetic neuropathy. Clin Biomech 2009;24(8):687-692.

21. Fernando DJ, Masson EA, Veves A, Boulton AJ. Relationship of limited joint mobility to abnormal foot pressures and diabetic foot ulceration. Diabetes Care 1991;14(1):8-11.

22. Goldsmith JR, Lidtke RH, Shott S. The effects of range-of-motion therapy on the plantar pressures of patients with diabetes mellitus. J Am Podiatr Med Assoc 2002;92(9):483-490.

23. Flahr D. The effect of nonweight-bearing exercise and protocol adherence on diabetic foot ulcer healing: a pilot study. Ostomy Wound Manage 2010;56(10):40-50.

24. Ritzline PD, Swanson J. The effects of a home exercise program on ankle range of motion and step length in people with type 2 diabetes: A blinded cross-over design pilot study. Presented at the annual meeting of the American Physical Therapy Association, Boston, June 2010.

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