Activity Wheel Helps Gauge Effect Exercise Has On Breast Cancer

Students from Colorado State University’s Department of Mechanical Engineering are teaming up with the university’s Cancer Prevention Laboratory to build equipment that studies the effect exercise has on the development of breast cancer. The student engineering team has developed a computer-operated, adjustable-speed, motorized "activity wheel" that reinforces running behavior with a food reward as part of a pre-clinical testing model.

Henry Thompson, director of the Cancer Prevention Laboratory and professor in the Department of Horticulture and Landscape Architecture, said physical activity may curb abnormal cell growth. "We are studying how energy balance – the balance between energy consumed through food and energy used through activity – influences cellular actions such as cell growth. The ability of cells to multiply abnormally is the key to the development of cancer," Thompson said. "It appears that maintaining energy balance by eating moderately and engaging in regular exercise puts the brakes on cell proliferation, and without cell proliferation, tumors can’t form."

A key to preventing abnormal cell development is vigorous physical activity. Thompson and his team of student engineers have developed a computer-driven activity wheel, which is like a high tech running wheel that hamsters might use. "This is the third iteration of the wheel," said Jay Waterman, a recent Colorado State Mechanical Engineering graduate who has worked on the project for the past two years. "We’ve added a brake to the wheel to control its speed and a control panel to better track how many revolutions the wheel makes, the intensity of the revolution and how many food pellets are dispensed to the rats."   

Pre-clinical testing of various exercise conditions are currently under way at the Cancer Prevention Laboratory using the student-designed wheels, setting Colorado State apart from colleagues around the world in the university’s ability to study the effects of physical activity on the development of cancer. Early results show that rats that exercised the most vigorously had the lowest incidence of breast cancer. The finding is similar to results in human studies conducted by other researchers, according to Thompson. "However, we unexpectedly found that the degree of protection against cancer declined as the time spent exercising increased."

Thompson noted that the intensity of any workout may be the key. "It’s possible that physical activity will benefit your body and reduce your risk of cancer, even if the pounds don’t melt away," Thompson said. "To influence energy balance, physical activity should be vigorous. Vigorous activity is defined as activity intense enough to boost the heart rate and work up a sweat.

"We agree with the current recommendation of 30 minutes of moderate physical activity per day to reduce cancer risk and 60 minutes of moderate activity or 30 minutes of vigorous activity per day to prevent weight gain and increase fitness. Brisk walking is an example of moderate activity. Jogging and aerobic dancing are examples of vigorous activity." However, Thompson noted that the ongoing work with the activity wheel underscores the fact that, while some exercise is good, more is not necessarily better.

The development of the activity wheel is the culmination of seven years of work and is the basis for a design project by Waterman and fellow Colorado State students Abby Wilbourn and Becca Beegles. Pre-clinical test models of the wheel are being refined with a goal of manufacturing a new generation of the wheels for use in a federally funded program of research investigating the role of lifestyle factors in reducing the risk for breast cancer as well as the likelihood of recurrence in cancer survivors.