TUESDAY, Nov. 15, 2016 (HealthDay News) -- Exercising during and after cancer treatment is safe and improves quality of life, fitness and physical functioning, new research indicates.

Benefits occurred with all types of exercise, said study author Brian Focht.

"Overall, resistance exercise, aerobic exercise -- and even a combination of aerobic and resistance -- resulted in improvement in fitness and quality of life and physical function," said Focht. He directs the exercise and behavioral medicine lab at the Ohio State University Comprehensive Cancer Center in Columbus.

More than 15 million people in the United States are cancer survivors. That number is expected to rise to 20 million within 10 years, according to background information with the study.

But current guidelines about exercise for cancer survivors are broad, suggesting simply that patients should try to be active, Focht noted.

The study team evaluated the effects of exercise on both prostate cancer patients and breast cancer patients.

The prostate cancer study included 32 patients, average age 65. The men were all undergoing hormone therapy (androgen-deprivation therapy) for their cancer.

The researchers randomly assigned half of the men to a plant-based diet and an exercise program including strength training and aerobic exercise. The other half of the group was assigned to standard care and did not get instruction in plant-based diets or exercise.

At the end of three months, the exercise and diet group was walking three to four times more quickly in a timed walk test of about a quarter-mile than the usual care group. In addition, those in the exercise group lost an average of 4 pounds and 1 percent of their body fat, and said that their quality of life and ability to do everyday tasks had improved. Men who were in the usual care group gained about 1 percent body fat, although their weight was fairly stable, Focht said.

Focht was scheduled to present the findings Tuesday at the American Institute for Cancer Research's Research Conference in Washington, D.C. Research presented at medical meetings is viewed as preliminary until published in a peer-reviewed journal.

In the second study, published recently in the Journal of Community Support Oncology, Focht's team evaluated 17 previously published randomized, controlled trials looking at exercise programs for women undergoing chemotherapy or radiation treatment after breast cancer.

The studies varied in length from three to six months; some programs were based at home and others were supervised by researchers. On average, those who exercised had improvement in muscle strength, cardiovascular functioning and quality of life, the findings showed.

The studies didn't provide any information on survival, as that outcome was not reviewed, Focht said. No information on intensity of exercise and which type was best was available, either. "We can't accurately draw any conclusions about whether intensity matters," he said.

In the prostate cancer study, the researchers personalized the exercise so it was a comfortable intensity for each person, Focht said.

Jessica DeHart, an assistant professor of epidemiology at the City of Hope Cancer Institute's Beckman Research Institute in Duarte, Calif., also conducts research on how exercise can help cancer survivors. She said the new research shows that exercise is "not only safe, but beneficial" for cancer survivors.

The new findings solidify what is known, and also what is not yet known, DeHart said. "We can't say, 'This is the specific dose or specific type [of exercise],' " she said. "What the researchers did show is that if we are thinking about quality of life, it seems anything helps."

DeHart said she tells her patients, "Try for moderate activity, even going for a short walk."

More information

To learn more about exercise during and after cancer treatment, visit the American Cancer Society.