Episode 56: The Desk Jockey’s Manifesto: The Harsh Realities of Sitting
The Realities of Sitting
Computer workstation ergonomics cannot be discussed without also discussing sitting and the adverse health effects it has on us. With the advances in technology over the past two decades, we are now sitting more than ever before. On average, we spend about 9.3 hours a day sitting, while only 7.7 hours sleeping. Just think about your daily routine and how much time you spend sitting. If you’re like most people that have an office job, after you get up in the morning, you sit down to have breakfast, you sit down in the car on your commute to work, you sit all day at work including your lunch break, you sit on your drive home from work, you sit to eat dinner, and then you likely sit on the couch to watch television, read, or surf the internet. Some of you may get an hour of exercise at some point in your day, but it is easy to see that most of your day is spent sitting. Recent research has shown that this type of sedentary lifestyle is detrimental to your health, even if you exercise or live an “active lifestyle.”
Why is Sitting a Problem?
Your body is designed to move, so as soon as you sit down, your body shuts down at a metabolic level. When your muscles are immobile and not contracting, especially certain leg muscles, circulation slows down and the neuroelectrical activity in the muscles ceases, causing enzyme activity to drop by 90%. One of these enzymes, lipoprotein lipase, is responsible for breaking down fat to use as energy, and for shifting cholesterol from the bad kind (LDL) to the healthy kind (HDL). Within 2 hours of sitting, your good cholesterol (HDL) drops by 20%. In other words, the longer you sit, the more weight you gain. According to one study, within 8 months of starting sedentary office work, people gain 16 pounds on average. Furthermore, within 24 hours of being sedentary, insulin effectiveness drops by 24%, while your circulating insulin increases, drastically increasing your risk of developing Type II diabetes.
Over a lifetime of sitting, these adverse health effects add up and shorten life expectancy. One study that followed the health of 123,000 Americans between 1992 and 2006, showed that men in the study that spent six hours or more per day of their leisure time sitting had on overall death rate about 20 percent higher than men who sat for less than six hours per day. For women in the study who sat for more than six hours per day, the death rate was about 40 percent higher. Another study published in the journal Circulation that looked at nearly 9,000 Australians and found that for each additional hour of television a person sat and watched per day, the risk of dying rose by 11 percent. Other factors like age, sex, education, smoking, hypertension, waist circumference, body-mass index, and whether the person exercised or not did not significantly change the associations between hours spent watching television and all-cause mortality. Furthermore, a study published in the journal Lancet showed strong evidence that physical inactivity is directly linked to 6 percent of the burden of heart disease, 7 percent of Type 2 diabetes, and 10 percent for breast or colon cancer.
Sitting also wreaks havoc on the body’s muscles and joints. Your spine was not meant to stay in a seated position for long periods. The spine is slightly curved to resemble a slight S-shape. The curves help the spine distribute mechanical stress from body movement and gravity. When you sit, the lower back curve collapses, turning the spine’s natural S-shape into a C. You’re left to bear all of your weight through the pelvis and spine, unlike standing when you’re distributing weight through your hips, knees, and ankles. While using proper ergonomics and a chair with good lumbar support will help you maintain your spine’s natural curves, sitting still puts the highest pressure on your lumbar discs, even when using perfect sitting posture. Furthermore, your back muscles become overworked trying to maintain your posture as you’re no longer distributing your weight through your legs. The back muscles, ligaments, tendons, and disc cartilage become strained and will eventually weaken, which can cause many spinal problems.
Muscles also tend to adapt to whatever position they are in most. So if you sit in the same position for long hours at work each day, you will slowly reset your natural posture and your muscles will begin to resize themselves to accommodate your sitting posture. Over time, your body becomes more adept to sitting in a chair. The problem is that it makes you less adept at standing, walking, and running. Eventually, you might start to experience symptoms like neck pain, back pain, shoulder pain, headaches, hip pain, and/or tingling numbness in your extremities.
Sitting Is the Real Issue
As you’re reading this, you might say to yourself: “well I exercise regularly, so that should counter all of this.” Conventional wisdom has always been that if you watch your diet and exercise a few times a week, you would offset all of the time you spend sitting or being sedentary. Unfortunately, an increasing body of research on inactivity is showing that exercise alone will not undo the harmful effects associated with sitting. Sitting too much is not the same as exercising too little and they have independent effects on the body. Meaning that the amount of time you exercise and the amount of time you spend sitting are completely separate factors for things like heart disease and diabetes. Sitting in an office chair for 8 hours a day is bad for your health whether you go home and sit on the couch or go to the gym after work. Research has shown that we are exercising as much as we were 30 years ago.