When it comes to improving your health, decreasing the amount of time you spend sitting throughout the day is just as important, and maybe even more so, as is engaging in a daily bout of moderate- to vigorous-intensity exercise. Swedish researchers from the Karolinska University Hospital and the Swedish School of Sport and Health Sciences addressed this distinction between the two health behaviors in the February 4, 2010 online issue of the British Journal of Sports Medicine. They note that each behavior is characterized by separate metabolic and physiological processes that effect health.

In order to better understand this distinction, the authors state that a clarification of the definition of sedentary behavior is warranted. They point out that sedentary behavior should not be used as a synonym for a lack of exercise (e.g., going out for a run), rather, it should be used to define muscular inactivity during day-to-day tasks (e.g., sitting rather than standing at your work desk). Based on this concept, the researchers present a new model of "inactivity physiology" which suggests that sitting and limited non-exercise physical activity (e.g., gardening, sweeping, etc.,) should be viewed as a separate risk factor for disease.

During the 58th Annual American College of Sports Medicine Conference in Denver, Colorado earlier this month, Steven N. Blair, FACSM, of the University of South Carolina reiterated the importance of this new paradigm. Blair noted that too much sitting is not the same as too little exercise--each behavior has qualitatively different causal mechanisms and that too much sitting is associated with chronic diseases regardless of whether or not a regular exercise program is followed. He explained that the body's cells are always sensing the metabolic environment and responding to it. The entire day's worth of activity is what is most important to stimulate and signal these processes to promote health.

Blair discussed that exercise is not the perfect anecdote to sitting too much. "Exercise does not make you immune to the diseases caused by prolonged periods of sitting," he stated. In other words, one hour of exercise will not offset the ill effects associated with sitting for 6 hours at a time. The effects of breaking up periods of extended sedentary behavior with active tasks are immediate. Blair recommends:

• Stand while talking on the phone
• Conduct walking meetings or stand during an office conference
• Stand to greet visitors
• Walk to a co-worker's office to hand-deliver a message rather than sending an email
• Use the stairs instead of the elevator

References
Br J Sports Medicine doi:10.1136/bjsm.2009.067702

EIM Tutorial Lecture: "Inactivity Physiology: Misconceptions and Major Public Health Implications"; June 1, 2011