Sedentary behavior, independent of the practice or lack of exercise, may lower cardiorespiratory fitness levels, cardiologists at UT Southwestern Medical Center found.
The study, published in the online edition of Mayo Clinic Proceedings, set to determine the association between cardiorespiratory fitness and sedentary behavior, independent of exercise activity. Researchers examined 2223 participants, without any known heart disease and who had both cardiovascular fitness testing and at least one day of accelerometer data from the National Health and Nutrition Examination Survey.
Participants were stratified by sex, age, body mass index, and wear time, and researchers quantified bouts of exercise as mean minutes per day for each participant, while sedentary time was defined as less than 100 counts per minute in mean minutes per day. Cardiorespiratory fitness was derived from a submaximal exercise treadmill test.
The results showed that an additional hour of daily exercise activity was associated with a 0.88 metabolic equivalent of higher fitness for men and a 1.37 MET higher fitness for women. Furthermore, an additional hour of sedentary time was associated with a −0.12 and a −0.24 MET difference in fitness for men and women, respectively.
The findings suggest that two hours of sedentary behavior can be just as harmful as 20 minutes of exercise is beneficial, which led researchers to conclude that the risk related to sedentary behavior might be mediated, in part, through lower fitness levels.
Although previous studies have already reported that sedentary behavior was associated with an increased risk for cardiovascular outcomes, “the mechanisms through which this occurs are not completely understood,” noted in a press release by Dr. Jarett Berry, assistant professor of Internal Medicine and Clinical Science and senior author of the study.
According to him, the team’s new data suggest that “avoiding sedentary behavior throughout the day may represent an important companion strategy to improve fitness and health, outside of regular exercise activity.”
Researchers also found that when sitting for prolonged periods of time, “any movement is good movement, and was also associated with better fitness,” said Dr. Jacquelyn Kulinski, a recent graduate from the UT Southwestern Cardiology Fellowship Training Program and first author of the paper. To minimize the damages of these prolonged periods of sitting, she suggests that people “stuck” at their desk for while should “shift positions frequently, get up and stretch in the middle of a thought, pace while on a phone call, or even fidget.”
In addition, UT Southwestern cardiologists recommend taking short walks during lunch and throughout the day, using a pedometer to track daily steps, taking the stairs instead of the elevator, hosting walking meetings at work, and replacing a standard desk chair with a fitness ball or even a treadmill.