Doctors are starting to write prescriptions for a half-hour of weightlifting or a 2-mile walk, according to the Johns Hopkins Center for Dynamic Health, a newly formed group of clinicians and researchers who hosted a recent symposium on exercise as medicine at The Johns Hopkins Hospital.

With help from smartphones and wearable devices that automatically track movement, scientists are learning how bicep curls, jogging and other workouts can help prevent or slow the progression of conditions as varied as glaucoma, diabetes and depression.  

They are studying the mechanisms that give physical activity the power to heal and discussing optimal doses for particular patients and conditions. The goal, says Edward McFarland, professor of orthopaedics and shoulder surgery, is to take their findings “from bench to bench press,” with more doctors encouraging and even prescribing exercise.

The Center for Dynamic Health is led by James Ficke, director of orthopaedic surgery; orthopaedists McFarland and Richard Schaefer; and Kerry Stewart, director of clinical research and exercise physiology. The group is planning an annual symposium and other activities to support exercise research.

Here are five examples of how exercise is like medicine, from the group’s first symposium.

1. Exercise wards off diabetes. Rita Kalyani, associate professor in the division of endocrinology, diabetes and metabolism, says even a single bout of exercise can temporarily lower blood glucose levels in people with type 2 diabetes. The Diabetes Prevention Program found that exercise and dietary changes were more effective than a placebo or the prescription drug metformin in keeping patients with prediabetes from developing diabetes.  
2. Exercise fights glaucoma. Pradeep Ramulu, chief of the Glaucoma Division at the Wilmer Eye Institute, is finding that exercise can slow the progression of glaucoma, a degenerative disease that damages the optic nerve. The mechanisms aren’t known, he says, but appear to be related to the ability of physical activity to protect nerves from damage. His Visual Improvement with Physical Activity Study, testing whether a six-month walking regimen can improve the vision of patients with glaucoma, was inspired by a 32-year-old patient with glaucoma whose vision improved when she ran and worsened when she stopped. “Every time she comes in I can tell whether she’s been exercising,” he said.
3. Exercise helps patients with peripheral artery disease feel better and live longer. Exercise may be the only way to improve function and extend life for people with peripheral artery disease, says Elizabeth Ratchford, director of the Johns Hopkins Center for Vascular Medicine. Millions of Americans suffer from the circulation disorder, which impairs blood flow to the extremities, often causing intermittent leg cramps that interfere with walking and daily activities. Supervised exercise therapy is now available at some Johns Hopkins locations; the program encourages patients to walk until they feel moderate pain, then wait until the pain goes away before walking again. 
4. Exercise helps pediatric patients with cancer. Patients between the ages of 4 and 15 with acute lymphoblastic leukemia who exercised during and after treatment had improved strength, cardiopulmonary endurance, sleep, flexibility and health-related qualities of life, says Victoria Marchese, associate professor at the University of Maryland School of Medicine Department of Physical Therapy and Behavioral Science.
5. Exercise fights depression. A 2016 meta-analysis of exercise and depression found that exercise is as good as medicine or psychotherapy for treating depression, says Glenn Treisman, professor of psychiatry and medicine. One explanation may be that exercise releases cortisol, which fights inflammation in the brain. But Treisman said exercise also gives people a goal. “We can’t give our patients happiness,” he said. “They have to get it themselves.”