CHICAGO — On a recent Wednesday night, Cindy Gerstner, 42, strapped her feet into a rowing machine and began gliding back and forth with all the energy she could muster. This wasn't just a workout for Ms. Gerstner, whose stage IV breast cancer has spread to her brain, lungs, bones, and liver. It was a 40-minute dose of medicine.
“It's part of my treatment plan,” said Ms. Gerstner, a member of Recovery on Water or ROW, a crew team made up of breast cancer patients and survivors who believe exercise is a powerful tool to help keep cancer at bay. “It's almost as important as chemotherapy in helping me stay on this earth as long as possible.”
University of Illinois scientists recently received funding for a study that looks at whether riding a stationary bicycle during treatment can help dialysis patients.
The burgeoning “exercise is medicine” movement is championed by dozens of organizations, including the American College of Sports Medicine, the Chicago Park District, and cancer support groups. New national cancer guidelines urge both patients and survivors to exercise during and after treatment for 150 minutes per week, the same advice given to the general public.
Some big questions remain unanswered, such as what type and how much exercise is needed for what illnesses. In many cases, working out appears to relieve symptoms, but its impact on the natural course of the disease isn't known. And many physicians are cautious about prescribing something that can stress the body, especially for patients in the throes of a life-threatening illness.
“There's still a prevailing attitude out there that patients shouldn't push themselves during treatment,” said Kathryn Schmitz, an associate professor of epidemiology and biostatistics at the Abramson Cancer Center at the University of Pennsylvania school of medicine and lead author of the new guidelines.
Ms. Schmitz acknowledges that exercise is a stressor on the body but said resting too much also can have adverse effects.
If exercise isn't already a habit, of course, it can be intimidating. It's harder to do when you don't feel good. And “some people would truly rather take a pill,” said Holly Benjamin, an associate professor and pediatric sports medicine specialist at the University of Chicago.
“But once they do it, so many people feel so much better.”
In the past, breast cancer patients who had undergone surgery were told not to lift more than 15 pounds for the rest of their lives, fearing that strenuous effort would slow treatment or exacerbate conditions.
But Ms. Schmitz's groundbreaking work, published last year in the New England Journal of Medicine, reversed decades of cautionary advice by finding that slow, progressive weight lifting wasn't just safe; it could prevent lymphedema flare-ups.
Exercise can help people being treated for cancer cope with the side effects of chemotherapy, surgery, and radiation, including fatigue and the loss of muscle mass.
“It helps them get through treatment in better form,” said David Nieman, director of the Human Performance Labs at Appalachian State University and the author of several textbooks on exercise as medicine.
A handful of observational studies, meanwhile, have suggested that exercise could result in a 40 to 50 percent reduction in the risk for recurrence of breast cancer, said Ms. Schmitz, though randomized controlled trials would be needed to prove a benefit.
For a few conditions, including Parkinson's disease, there's hope that exercise can affect the illness itself. In animal studies, exercise improved symptoms and increased the level of brainderived neurotrophic factor, a chemical that protects cells.
“Exercise may modify disease by slowing the primary process of cell loss associated with Parkinson's disease,” said Cynthia Comella, a neurologist at Rush University Medical Center, who is currently investigating the effects on Parkinson's of regular exercise with a personal trainer.
For treatment of pediatric rheumatic diseases, “exercise has been overlooked,” said Bruno Gualano of the University of Sao Paulo in Brazil.
Traditionally, children with inflammatory diseases have been treated with drugs that can have side effects. But certain types of exercise can be safe and effective treatment for symptoms including muscle wasting, osteoporosis, insulin resistance, pain, and fatigue.
Exercise's greatest strength may be that it can work on both physical and emotional levels.
If some health advocates had their way, exercise would be the most widely prescribed “drug” in the country.
In Chicago, for example, any resident with an exercise prescription from a doctor for an obesity-related disease — including diabetes, high blood pressure, and asthma — can receive a free three-month membership to Chicago Park District fitness centers.
And for the past several years, the Erie Family Health Center, which provides care in Chicago's medically underserved communities, has encouraged providers to prescribe physical activity.
But research on whether the prescriptions are effective is limited and mixed. A study of Australian women between the ages of 40 and 74 found that exercise prescriptions increased physical activity and quality of life over two years, though falls and injuries also increased.
Choosing specific goals — such as reducing blood sugar by 20 points or improving blood pressure — or setting someone up with a personal trainer was also found to be more effective than just telling someone to go exercise.
“People who aren't regular exercisers need a lot of guidance,” said Dr. Benjamin.
“You have to empower the patient, give them concrete benchmarks and provide follow-up and feedback,” Dr. Benjamin said.
Despite a burgeoning “exercise is medicine” movement, physicians remain more likely to refer someone to a specialist than to a health club, in part because they may be unfamiliar with fitness and not sure how receptive patients will be, said Indiana University physical activity expert NiCole Keith.
“Unless physicians themselves are athletes they're not always well educated in this, and it's a big barrier to effectiveness,” Dr. Benjamin said.