It helps protect you from heart disease, makes it easier to drop those extra pounds and even lowers your risk of developing breast cancer.
Now Dr. Anne McTiernan and colleagues in the Hutch's Public Health Sciences Division hope to add another benefit to the growing list of good reasons to exercise.
The APPEAL study - A Program Promoting Exercise and Active Lifestyles - is the first research project to look at how moderate to vigorous intensity exercise may lower risk of colon polyps and colon-cancer development.
The four-year, $4 million study funded by the National Cancer Institute is one of growing number of research projects that are proving that exercise does more than just make people feel fit.
"Exercise promotion has been around for ages," said Angela Morgan, APPEAL study coordinator. "But it's only been in recent years that there have been careful studies showing that exercise can reduce the risk of developing certain chronic diseases and cancer."
Although the connection between exercise and colon-cancer prevention is not new, Morgan said, no studies to date have been definitive.
"A lot of observational studies demonstrate that exercise can reduce colon-cancer risk," she said. "But it hasn't been clear in those studies whether other lifestyle factors might be involved. APPEAL is the first study to look at the direct effect of exercise on certain risk factors associated with colon-polyp formation and colon cancer."
More than 100,000 Americans are diagnosed with colorectal cancer each year, and about 50,000 die from the disease. Adenomatous polyps, precancerous growths on the lining of the intestine, are a risk factor for this form of cancer.
50-percent risk reduction
"Epidemiologic studies that have measured physical activity indirectly have indicated that a higher activity level is associated with a 50 percent reduction in risk of colon cancer," McTiernan said. "We hope to show that exercise is a prevention that allows people to take control of their own health to help reduce cancer risk."
APPEAL is recruiting 100 men and 100 women, ages 40 to 75, who are not regular exercisers and who have either a history of colon polyps or have had a colonoscopy in the past three years.
Participants will be randomized into either an exercise intervention group, whose members will take part in a personalized, 12-month exercise program, or a delayed-exercise (control) group.
Each participant in the intervention group will meet three times a week with an exercise specialist for moderate to vigorous 60-minute exercise sessions after undergoing a six-week screening process.
"All participants will first be given a physical exam, a full blood screening panel and tests to evaluate them for heart disease," Morgan said.
"We screen them from top to bottom to ensure that it is safe for them to participate in a vigorous exercise program. If any cardiac irregularities are noted during the treadmill test for screening maximal effort, we refer them to their primary-care provider for further evaluation."
PHS staff scientist Dr. Rebecca Rudolph oversees the treadmill testing, which includes standard tests that monitor heart rate and rhythm.
Besides sessions with an exercise specialist in an exercise facility, for three additional days each week participants must agree to exercise on their own.
'As easy as possible'
"We try to make that as easy as possible for them by allowing them to use the exercise facilities on those days and providing them with information about organized walks or runs they can participate in," Morgan said.
Participants can work out at the Washington Institute of Sports Medicine in Totem Lake or at the Hutch Exercise Research Center located on the 13th floor of Metropolitan Park East. In the future, the study hopes to open a south end facility.
Significant donations from the Seattle Foundation and Precor, Inc of Bothell allowed the on-site facility to be equipped with brand new, state of the art exercise equipment.
"We'll be equipped to measure virtually every physical parameter associated with exercise testing," Morgan said.
"The equipment is so sensitive - and needs to be calibrated so precisely - that only specially trained staff will operate it. That's especially important because any changes in equipment calibration can compromise our research."
The impact of the study will be measured by examining changes that occur in the mucosal lining in relation to polyp formation. Prior to and after completion of the intervention, participants must undergo a flexible sigmoidoscopy, a procedure that allows visualization of the rectum and lower portion of the colon and permits a doctor to take biopsy samples of the mucosal lining. Rudolph performs the flexible sigmoidoscopies.
"Basically, what we want to examine is the amount of cell growth and cell death occurring at the lining of the intestine," Morgan said. "Polyp formation is a sign that there is excessive cell growth and too little cell death. We want to determine if the balance between these parameters becomes more normal after the intervention."
Dr. Paul Lampe will analyze markers that indicate the levels of cell growth and cell death. Dr. Johanna Lampe will play a key role in the interpretation of these data.
The study also will monitor levels of prostaglandin, a hormone that has been implicated in colon cancer when it is present in excess levels. Dr. Irena King will measure levels of prostaglandin in the blood and urine as well as in the intestinal mucosa (lining).
Other Hutch investigators on the project include Dr. John Potter, head of the Cancer Prevention Research Program and Dr. Deborah Bowen, a health psychologist and Dr. Yutaka Yasui, study statistician. Dr. Christina Surawicz, Chief of Gastroenterology at Harborview Medical Center, is an investigator that serves as the study's crucial recruitment contact with Seattle gastroenterologists as well as providing training and supervision for the sigmoidoscopy procedures