The Sitting Sickness



If you've heard that life is movement, it's true. If you've heard that just sitting around can kill you, it's also true. Physical inactivity is the fourth leading cause of death worldwide! You may have heard the media reporting recently on several studies showing that prolonged sitting significantly increases the risk for death, including death from heart disease and cancer, but I'm not sure this news has really hit home yet.

Most people know that exercise is critical for health and preventing disease, but the issue of physical activity and inactivity is much bigger than exercise. Regardless of the amount of exercise one performs, the level of aerobic fitness one exhibits, or whether a person is thin or overweight, stillness still kills. Apparent health and leading an otherwise healthy lifestyle does not compensate for extended periods of sitting around, and we Americans do a great deal of sitting around. We've even built over 4 million miles of roads so we can sit still while we go places! In fact, the infrastructures and cultures of most developed nations seem to be perfectly designed for physical inactivity.

The average American watches around 40 hours of television per week, while those over 65 watch an average of 48 hours per week. Sitting is certainly one factor that contributes to the negative health consequences of these technologies. But there is another gigantic part of modern life in which sitting is the dominant physical activity (or inactivity!). I'm talking about work! The average American spends 40 hours per week watching television, 50 hours per week sleeping, and about 45 hours working (unless unemployed/retired). That leaves about 33 hours per week for other things, many of which also involve sitting (eating, checking Facebook and email, texting, driving/traveling... sometimes all together, but that is a different newsletter).

Many people, of course, work longer hours and, while some types of work are physically intense, "sitting jobs" are common. One study showed that office workers spend 95% of their time at work sitting and 82% of this time was nearly motionless! For many people, then, work contributes 45 hours of or so of physical inactivity per week embedded within 168 hours of mostly physical inactivity per week! Yet, work can also be 45 hours or so of physical activity per week if one chooses! While it is obvious that television viewing and other sedentary leisure activities can easily be replaced by more physically active leisure pursuits, we have overlooked the workplace as an additional source of potential physical activity!


This is a rather recent realization, and you may have observed, in response, the growing trend of treadmill desks and stand up desks. However, it is not that simple. Standing, per se, is not really the answer and we don't all need treadmill desks either. In this article, I want to explore the fascinating physiology of physical inactivity and muscle endocrinology a bit, and then focus in on the key to avoiding the harms of physical inactivity. Throughout the article, I'll use the term "low-amplitude low-intensity movement". This term refers to very small movements with minimal to no displacement of the body (low-amplitude) and which produce minimal to no sense of effort (low intensity). The bottom line is, physical activity in the form of low-amplitude low-intensity movement is critical for health and no supplement regimen, dietary modification, or exercise plan can compensate for its lack! It is time that we stand up to our sitting culture and demand opportunities to move!

   The Many Faces of Sitting

The data is solid; prolonged sitting is unhealthy and it doesn't matter so much whether that stillness is in front of a television or a desk, at home or work, or in a car or airplane. Not surprisingly, the harmful consequences of prolonged sitting are numerous. Studies have shown that prolonged sitting shortens life expectancy, increases fat accumulation around the heart, and is associated with metabolic syndrome (abnormal cholesterol or triglycerides, high blood pressure, insulin resistance, and abdominal obesity).

In an excellent article from 2009, Bente Petersen describes what he calls the "diseasome of physical inactivity". He says, "the diseasome of physical inactivity [is] mediated through an interdependent cycle of myokine imbalance or deficiency, immuno-endocrine dysfunction, and abdominal obesity". His argument needs little additional justification as it is thoroughly supported by modern physiology. The physical and physiological derangements which underlie Petersen's diseasome of physical inactivity include abdominal obesity, chronic inflammation, insulin resistance, atherosclerosis, neurodegeneration, and tumor growth. The resulting cluster of diseases includes type 2 diabetes, cardiovascular disease, depression, dementia, colon cancer, and breast cancer. These relationships are illustrated in "figure 1" below. Remember, by physical inactivity, we are not just referring to a lack of exercise. Instead, we are referring to prolonged periods of sitting still, regardless of how much exercise is done.




 
   Don't Just Sit (or Stand) There, Move Something!

In addition the role muscle contraction plays in the optimal function of the endocrine system and human physiology in general, the mechanical forces from muscles contracting in the setting of gravity provide numerous direct benefits as well. For example, the articular cartilage in the joints and intervertebral discs in the spine require these mechanical forces for nourishment and waste product removal. These tissues have no direct blood supply and rely on the "milking" or "pumping" action of movement for health. Without movement, these tissues desiccate (dry) and degenerate (crack and thin), resulting in osteoarthritis and degenerative disc disease. Many are surprised to realize that movement prevents arthritis rather than contributes to it.

Similar to joint cartilage and intervertebral disc health, skeletal health also requires mechanical forces from gravity and muscle contraction, which stimulate bone mineralization. With sitting, the force of gravity begins in the pelvis and transmits up the spine, leaving the lower extremities isolated in anti-gravity. The result may be reduced bone mineralization in the lower extremities, including the hips, contributing to osteopenia or osteoporosis of the hips over time.

As if this were not enough, sitting and physical inactivity promote deconditioning of the abdominal and lower back muscular while at the same time placing exaggerated and imbalanced forces on non-muscular lumbar (lower back) structures like ligaments and intervertebral discs. The result is an increased vulnerability to lower back injuries, degenerative disc disease, disc herniations, nerve impingement syndromes, and lower back pain. Regular co-contraction of truck flexors and extensors (abdominal and lower back muscles) is critical to maintaining optimal lumbar spine curvature and protecting intervertebral discs from desiccation and herniation.

Finally, no discussion of the mechanical benefits of movement would be complete without mentioning the other half of the circulatory system, the venous pump. We all care a great deal about keeping our hearts pumping. After all, it is critical that blood goes through the lungs and out to our organs. Yet, why don't we care so much about that blood getting back to the heart? The heart does not suck blood back up, it just relaxes and relies on venous pressure to fill it up all the way. Some of this pressure is created by breathing and most people fail to breathe correctly, but I'll save that discussion for another day. The rest of this filling pressure largely relies on muscle contraction and venous valves. The muscles of the lower extremities, especially, work against gravity like a heart for the veins, squeezing blood back up to the heart for the arteries, in the chest. Without regular muscle contraction, the system breaks down. Blood flow slows down, venous blood volume and pressures build, arterial and capillary pressure builds in response to "drive the blood through", cells are under nourished and have a hard time getting rid of waste products, venous valves get stressed and fail, varicosities develop and enlarge, legs and muscles may ache, platelets and clotting factors mingle, blood clots can form, and it only gets worse from there.

   Wobble While You Work

Wobble boards have been used for years by athletes and trainers to increase lower extremity and core strength, as well as proprioception (dynamic sensation and control of the body's position), with the intention of preventing injuries and enhancing performance. They have also been used in physical therapy and rehabilitation work to improve the balance, proprioception, strength, and agility after injury, surgery, and stroke. The technology is simple, consisting of a flat standing surface with some type of grip and a rounded rocker or "wobble" underneath. Most are made of plastic or wood, and the wobble height varies in order to provide different degrees of difficulty. Some boards have adjustable wobble heights, which is a nice feature for beginners.

Wobble boards engage the neuro-musculo-skeletal system from the feet through the legs, into the trunk/core and even into the upper extremities and head. This not only improves balance and proprioception, but enhances core strength and reverses hip and lower back instability, both causes of injury and pain. Studies have shown that the use of wobble boards significantly improves the speed of muscle reflexes, enhances the synergistic coordination of the body's muscular system, and develops the precision of the complex neuromuscular interactions which determine balance and agility.



Most relevant to the above discussion, however, is the fact that wobble boards (and most other unstable surface devices) stimulate continuous very low-amplitude and low-intensity muscle contraction through the body. These movements are very small and one can quickly learn to type and perform routine office work while standing on a wobble board. In fact, most will eventually be able to stand on the board with one foot and do such work! One's control of the board might become so great that smaller and smaller movements and adjustments are needed, which reduces the muscle contraction involved. Since the intention is to maximize muscle contraction, the goal at this advanced stage is to continue to introduce movement by intentionally wobbling the wobble board, trying different stances (heel to toe, switching left and right foot forward, etc.), doing deep knee bends on occasion, and raising the arms above the head. Keeping the knees slightly bent at all times helps to maintain a balanced posture and promote movement. Start with 1 hour a day on the wobble board, always listen to your body, and increase your time slowly as you feel able.

Wobble boards are not the only option for creating an unstable surface. Various types of "balance boards" are available and all offer various degrees of movement and difficulty. Rocker-roller type boards like Indo Boards and curved boards like Spooner Boards are just two examples. Whatever you choose, be sure to start slowly and carefully, and try it in a safe and soft space before taking it to the office!
                                                





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