Extra Daily Steps Can Go the Distance in Improving Health

MU researcher will examine the risk of diabetes and heart disease in response to inactivity

Dec. 2, 2008

Story Contact:  Kelsey Jackson, (573) 882-8353, JacksonKN@missouri.edu

COLUMBIA, Mo. –Despite the growing evidence showing a link between physical activity and health, much is unknown about how physical inactivity affects the exact mechanisms underlying the development of heart disease and diabetes. A new University of Missouri study will examine how an acute transition from an active to inactive lifestyle affects glycemic control (control of blood sugar levels), and if changes in blood vessel function play a role.

“Our goal is to provide evidence that increasing daily steps can significantly improve an individual’s health and, conversely, that reducing daily steps puts individuals at risk for metabolic and cardiovascular disease,” said John Thyfault, assistant professor of Nutrition and Exercise Physiology in the MU College of Human Environmental Sciences and health scientist in the Harry S. Truman Veteran's Administration Hospital. “People need to be aware that the risk of being sedentary is not just the things we can see but things we can’t see.  One of the primary causes of cardiovascular disease is poor glycemic control.  When there is poor glycemic control, blood vessels are constantly exposed to dramatic changes in blood sugar levels, thus causing damage to cardiovascular tissue. Our preliminary data show that even active, healthy people will develop a loss in glycemic control levels after only a few sedentary days.”

In the study, researchers will recruit one group of active, healthy individuals who will be studied before and after they transition to a physically inactive lifestyle for a short period of time.  Another group of sedentary, overweight individuals will be studied before and after they transition to a more physically active lifestyle by increasing their daily steps. While the subjects are being studied, participants will wear monitors to record their blood glucose and physical activity levels every minute of the day. Participants also will eat standardized meals that include foods high in sugar (pasta, white bread, soda and juice) to challenge their glycemic control.

The overall hypothesis is that day-to-day physical activity levels directly impact glycemic control. The researchers also will determine if changes in blood vessel function play a role in the loss of glycemic control.  In a parallel component, rats will be given access to voluntary running wheels in which they will run 5 to 10 kilometers a night. The rats will be transitioned to physical inactivity by locking the wheels.  The studies in rats will allow for studies at the cellular level of blood vessels and skeletal muscle that can’t be done in humans, Thyfault said.

“While the human experiments will provide us with important insight into the health implications of physical inactivity, the animal experiments will provide us with further insight into the molecular and biochemical causes of metabolic and cardiovascular dysfunction resulting from physical inactivity,” Thyfault said. “We predict that both the healthy and overweight groups will have a change in glycemic control and blood vessel function, as they change their physical activity levels.”

This study is funded by the MU Institute for Clinical and Translational Science. The Institute is a campuswide commitment to interdisciplinary collaboration in clinical and translational science. The Institute supports the creation of an optimal academic environment for the MU research community to extend and translate recent scientific advances and embrace the value of an inclusive scientific community that engages practitioners, consumers, families and stakeholder, in the educational and research process. The goal of the Institute is to have a meaningful impact on the quality-of-life and the health of Missouri citizens, the nation and the world.

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