Please don't be seated

If you had to guess, how many hours in the day do you spend sitting? According to research from private medical insurer AXA PPP, British workers spend up to 9 hours a day sitting down. This means our daily sit time is equivalent to a flight to the Caribbean - although this is likely to have increased since lockdown began.

You may have heard the saying "sitting is the new smoking". This is from Dr. James Levine, a professor of medicine at the Mayo Clinic. In an interview with the LA Times, he said: "Sitting is more dangerous than smoking, kills more people than HIV and is more treacherous than parachuting. We are sitting ourselves to death."

“Most of sitting’s negative effects relative to health occur when people sit for an extended period of time and don’t get up and move about,” says William Haskell, PhD, a professor at the Stanford Prevention Research Centre and the Division of Cardiovascular Medicine at Stanford University School of Medicine. Here are some of his findings regarding the health impacts of prolonged sitting:

• Deep Vein Thrombosis (DVT): In the short term, sitting too long increases the risk of blood clots forming, usually in our legs. Those clots can dislodge and travel to the lungs, where they can cause a potentially fatal condition known as a pulmonary embolism. When we are healthy, our blood tends to have anti-blood clotting factors. Sitting turns off these factors and inhibits other factors that help dissolve clots when they do form. “More physically active people tend to have a better blood profile in terms of these anti-clotting factors than sedentary people,” explains Haskell. While anyone can be at risk of DVT during prolonged sitting, you’re more at risk if you’re older, have already had DVT, or lead an inactive lifestyle.
  

• Impaired blood flow: Sitting too long causes our vascular system to work harder to get blood flowing through our body and back up to the heart. As a result, our blood pressure may increase. “When you’re in a chair and your legs are bent, it’s harder for your blood to flow freely,” says Bethany Barone Gibbs, PhD, a cardiovascular researcher and assistant professor in the department of health and physical activity, and clinical and translational science at the University of Pittsburgh.
  

• Reduced glucose disposal: “If we just sit and don’t move, our glucose levels become elevated, which can cause vascular damage, leading to diabetes and heart disease long term,” says Gibbs. Sitting for prolonged periods multiple times a day exacerbates the effects.
  

• Increased lower back pain: Gibbs’s own research shows that sitting too long increases chronic lower back pain in office workers. The hip flexor muscles that connect your thighs, hips, and lower back become shortened during prolonged sitting. Then, when you stand, the tightened muscles cause pain, explains Gibbs.

Breaking up bouts of sitting reduces the risk of developing serious health consequences. But standing alone may not be the answer, since you’re going from one static position to another. “We still have questions about how much benefit just standing at your desk has for long-term health,” says Haskell.

When it comes to muscular and heart health, getting up from a seated position and moving may be more beneficial than standing alone. “You have some muscle contraction going on when you’re standing, just to support yourself, but it’s been shown in animals and humans that important enzymes get enhanced in skeletal muscle as a result of contraction,” says Haskell, adding that just one session of aerobic exercise increases enzymes which contribute to favourable changes in blood cholesterol.

Researchers are still trying to pinpoint the maximum time it’s safe to sit and how long of a break you should take to make a difference. For now, aim to get up and move for two to five minutes after every 30 minutes to an hour of sitting, whichever is most feasible for you.

“Every time you take a little break, you’re turning your body back on which is kind of turned off when you’re sitting too long,” says Gibbs.

To avoid the initial muscle soreness that comes with interrupting a sedentary lifestyle, Matt Buman, PhD, who researches sedentary behaviour interventions, advises people to build up to longer standing times. “We found that people who work up to these activities slowly tend to be more successful in the long run,” he says.