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Dr. Campbell: Can sitting at your desk cancel out the benefits of exercise?

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There is now evidence that time spent at your desk may actually reverse the benefits that you have obtained from that quick pre-work trip to the gym or a run or walk during your lunch break.

The study was published this month in the Mayo Clinic Proceedings.

We have known for a long time that a sedentary lifestyle can increase your risk for heart disease, diabetes, high blood pressure, and other chronic disease—this is typically mediated through the development of obesity—de-conditioning of the muscles and the cardiovascular system can certainly lead to poor cardiac health.

Previous studies have tied too much time spent sedentary to a variety of health problems, including heart disease, blood clots, a large waistline, higher blood sugar and insulin, generally poor physical functioning, and even early death.

Another previous study on sedentary men published in January of this year showed that men who are sedentary are much more likely to develop congestive heart failure over their lifetime. Other studies published in the last year have shown that excessive sitting and excessive screen time (watching TV, etc) in adults is associated with a higher risk of certain types of cancers (particularly colon and endometrial/uterine cancer) and other negative health outcomes.

Now , a new study has shown that sitting at a desk or on a couch, etc for two hours or more cancels out the beneficial effects of 20 minutes of exercise.

Sedentary behavior involves low levels of energy expenditure activities such as sitting, driving, watching television, and reading, among others. The findings suggest that sedentary behavior may be an important determinant of cardiorespiratory fitness, independent of exercise.

In the study, 2,200 people were studied. Their cardiorespiratory fitness levels, average daily exercise, and sedentary behavior were examined in a survey. What they found was that in those that had long periods of sitting, they had worsened cardiac outcomes. However, if those that did sit for long periods of time actually moved, fidgeted, stretched, or paced—they had improved cardiac fitness.

The CDC recommends that adults between ages 18 and 64 get at least 2.5 hours of moderate-intensity exercise or 75 minutes of vigorous-intensity exercise a week. They should also do muscle-strengthening activities at least twice a week.

The exact mechanism is not known, however, excessive time sitting can lead to obesity and obesity-related illness. In addition, sitting for long periods of time can result in de-conditioning and muscle atrophy (weakening). We also know that prolonged sitting can lead to higher levels of blood sugar and insulin resistance which is associated with the development of heart disease and certain cancers such as colon cancer. In addition, high levels of insulin and blood sugars can lead to chronic inflammation and chronic inflammation can lead to heart disease.

To stay active and combat sedentary behavior, I 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 desk, if possible.

To get in touch with Dr. Campbell, you can head to his website, Facebook page or message him on Twitter.

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