Why Exercise Won't Counteract The Effects Of Sitting All Day
I admit it. I'm a standing addict. I use a standing desk when I see patients; at conferences my spot is always in the back so I can roam the edges of the room; at restaurants I own the bar seat so I can push the chair back and stand. I'm not happy on airplanes. On a recent trip, I told the flight attendant that sitting for the next 90 minutes was going to shorten my life span, something I'm not in favor of, but she didn't take kindly to my suggestion to help her serve drinks, so I went back in my seat.
It seems like it was only a few years ago that sitting was an activity that you could do on occasion, free of guilt and stares. We can all blame (or thank) Dr. James Levine of the Mayo Clinic for the change in our perception of chair time and its relationship to health outcomes.
As the number of scientific studies pointing out the health risks from sitting for long periods, including early death, are published at a fast and furious pace, it's more imperative than ever that we redefine how we conceive of our sedentary lives.
The science is redefining social and work norms including office design, meeting platforms and restaurant layouts. Dr. Levine began this craze about 10 years ago when he had overweight and thin people wear underwear with multiple sensors in them to track their activity (I kid you not). He observed that the difference in calories eaten between obese and thin test subjects was narrow, but obese individuals moved less while thin people enjoyed or non-exercise activity thermogenesis, or NEAT. So keep shaking those legs at work!
New data this week now firmly associates sitting and heart disease, and I hope you're standing up when you read this. The new data was presented in San Diego at the American College of Cardiology annual meeting. Heart CT scans and physical activity records of more than 2,000 adults living in Dallas were analyzed, and the researchers found that each hour of sitting per day was associated with a 14 percent increase in coronary artery calcification. Coronary calcification is a sign of damaged heart arteries and can increase the risk of a heart attack.
What was more shocking was the amount of heart artery damage from calcium was not associated with exercise or other risk factors. The researchers didn't just depend on questionnaires about sitting time, but used accelerometers to actually track daily movement, similar to what Levine did.
Of course, statistical associations do not prove causation, but it's shocking that extended sitting appears more dangerous than skipping exercise in your daily routine. The lead author, Jacquelyn Kulinski, M.D., summarized the findings as "how much you sit every day may represent a more novel, companion strategy (in addition to exercise) to help reduce your cardiovascular risk." Heart disease joins other chronic diseases linked to excessive sitting and "wheels on the ground" now represents a potential major health risk for Western society.
Other health conditions linked to time in the chair include:
- Diabetes mellitus
- High blood pressure
Sitting has been found to result in changes in metabolism in as little as 30 minutes, including:
- Higher levels of "bad" LDL cholesterol.
- Lower levels of "good" HDL cholesterol
- Higher blood sugar levels and reduced insulin sensitivity
- Higher blood pressure
- Lower mental alertness and positivity
- Higher measures of inflammation
So what are we to do? Not only does it appear that you can't out-exercise a crappy diet, but you can't out-exercise a sedentary desk job.
The amount of activity needed to improve the response to prolonged sitting is small; even light walking two out of every 20 minutes improves glucose metabolism. Yale's Dr. David Katz developed free videos demonstrating activity bursts that can be done "everywhere, every day."
Incorporating this kind of program at work (or on an airplane flight) can do wonders to overcome the impacts of prolonged sitting. A movement is growing of people standing up for their health at home, play and at work, and I hope you join in. Sir Isaac Newton may be most famous for describing gravity, the force that keeps us in our chairs, but we would be far healthier if we heeded his source of inspiration: standing. As he himself said, "If I have seen further than others, it is by standing on the shoulders of giants."