For years, researchers and exercise professionals have been proclaiming the health benefits of regular cardiovascular exercise. There is strong scientific evidence that moderate-to vigorous-intensity exercise plays a significant role in preventing cardiovascular disease, type 2 diabetes, obesity and some cancers.
Presently, the science of sedentary behavior, also called inactivity physiology, is an emerging field of research in health, fitness and medicine. This new field involves the study of sitting for extended periods of time and the biological ramifications associated with too much of this kind of behavior. Being sedentary is a distinctive form of human behavior and should not be regarded simply as the endpoint of the physical activity continuum. In the United States, adults and children spend the majority of their non-exercising waking day in various forms of sedentary behavior, such as riding in a car, working at a desk, eating a meal at a table, playing video games, working on a computer and watching television.
So what are some of the harmful effects of too much sitting? Most individuals can sit for many hours at a time, day after day. In fact, of the 16 hours of waking time in a day, more than 90% may be spent in sitting behaviors, even for the physically active person.
Initial findings on the hazardous effects of sitting behavior came to light in the 1950s, when researchers showed that compared with their inactive counterparts, men in physically active jobs had less coronary artery disease during middle age, and the disease they had was less severe. In addition, disease developed later in life among the physically active men.
In a recent study, one important finding was that physical activity does not cancel out the ill effects of too much sitting. This is true even for people who meet the current minimum physical activity guidelines of 30 minutes of moderate to vigorous intensity exercise per day, most days of the week.
Scientists found that when rats are not allowed to stand, there is a very dramatic drop in lipoprotein lipase, the enzyme in the leg muscles that captures fat (triglyceride) out of the blood to be used by the body as fuel. Thus, with consistent sitting, blood triglyceride levels start to soar, elevating the risk for CVD. Scientists hypothesize that this same physiological phenomenon occurs in humans.
Also noted was that a clinically relevant decrease in HDL (“good”) cholesterol is also observed with long periods of sitting (on a daily basis). Therefore, according to this early research, sedentary behavior appears to have a significant effect on some of the main factors that contribute to CVD.
Evidence indicates the physiological mechanisms associated with extensive sitting are different from the physiological benefits associated with consistent cardiovascular exercise. In addition to an existing exercise program, here are some innovative approaches to reducing sedentary behavior. Following is an example of how to create a metabolic profile, with a case study on how to implement a plan to reduce sedentary behavior.
Develop a waking-day metabolic profile timeline. Basically, write down in a timeline format what you do from the time you wake up from the time you go to bed and how long you are performing that activity. This timeline serves as an awareness index to help realize how much sitting is occurring on a daily basis. The next step is to find ways to sit less and stand more throughout the day, particularly during sustained periods of sitting. This leads to the concept of incorporating frequent episodes of spontaneous physical activity throughout sustained sitting times. This type of energy expenditure is called non-exercise activity thermogenesis (NEAT). It is encouraged that all individuals add activity to their daily life wherever and whenever possible. So, once the timeline is completed, the next objective is to incorporate bouts of spontaneous physical activity.
Let’s do a case study of a client whose metabolic profile (timeline) shows that person sitting at a desktop computer workstation for 5 days a week for 4 hours in the morning and 4 hours in the afternoon, then watching TV and reading for 2 hours each night.
Spontaneous physical activity options to break up the sustained sitting periods during work hours might include (but not limited to) the following:
- Stand up and get some water.
- Walk to the farthest bathroom in the work site facility (if multiple bathrooms are an option).
- Stand and/or walk around the room while on the telephone.
- Take a 5-minute walk break with every coffee break.
- Don’t email office colleagues; walk to their desks instead.
For the two-hour time frame spent watching TV, some of these options might work:
- Set a stationary piece of cardiovascular equipment near the TV, and use it for several minutes every half hour.
- Stand up and do some lunges or squats during commercials.
- Get up and walk around the house after reading so many pages.
Sedentary behavior can be harmful to one’s heath, so sit less and move more. We can do it!