A sedentary lifestyle is defined as a life style in which no physical exercise is performed and major part of the daily schedule is spent sitting. Sedentary lifestyles affect the body through different mechanisms. Sedentary activities decrease muscle oxygenation, protein transport, fatty acid transport, amino acid transport, hormone transport, and estrogen metabolism. Over time these decreased levels of hormones begin to have negative effects on various parts of the body including the cardiovascular system. Some of these adverse effects include increased blood pressure, increased heart rate, elevated blood sugar levels, decreased sex hormones (estrogens), osteoporosis, and cancer.
Obesity is often associated with a sedentary lifestyle. Although obesity is not directly caused by sitting, there are multiple links between sedentary behavior and increased body mass index ( BMI ) among overweight or obese people. One study revealed that women who sat for more than five hours a week were more likely to be obese than women who sat for less than five hours a week. This finding suggests that obesity may be partially caused by sedentary behavior. Another study found that women who sat at least eight hours a week were more likely to smoke marijuana and had more sedentary behavior than women who sat for less than eight hours a week. Both smoking and sedentary behavior were more prevalent among African American women than among white women.
The relationship between sedentary lifestyles and mortality is also clear. Those who are sedentary spend less time with active movement, increasing the risk of all sorts of mortality. Smoking and obesity are evident risk factors for all kinds of cancers and death, even cancer mortality. Cancer, in particular, is exacerbated by sedentary lifestyles and is clearly connected to poor health risks.
Besides the obvious health risks of a sedentary lifestyle, there are other physiological changes that take place. The digestive system and metabolism are two organs affected. In a sedentary lifestyle, the body’s metabolic processes are slow. The body burns through calories more slowly, leading to increased fat storage and to potential for diabetes, especially in obese people. The slower metabolic processes and elevated caloric intake lead to lower insulin sensitivity, which in turn leads to higher blood pressure, all of which are clear risk factors for cardiovascular disease.
Obesity and all-cause mortality have been connected with sedentary behavior for many years. But the new evidence points to the fact that there is a clear association between sedentary behavior and poor health outcomes independent of the relationship between obesity and all-cause mortality. While watching television, for example, may not directly cause weight gain, it seems to be a strong indirect cause. People who do not move around enough or engage in vigorous physical activity are at a much higher risk of becoming obese, even when they do not have weight problems.
Finally, the link between sedentary lifestyles and poor health outcomes is also evident in the types and intensity of physical activity. For instance, while walking in a park may not fetch one with the immediate physical exercise needed to reduce weight or to correct metabolic imbalance, taking a brisk walk outside in the sunshine can help burn off some of the extra calories consumed during the sedentary lifestyles. And while watching television is not directly tied to weight gain or weight loss, the prolonged sedentary lifestyle associated with this mode of entertainment leads to low energy levels and poorer mental health, as well as higher risks for poor cardiovascular health and for developing depression. The bottom line is that if people want to improve their health and reap the benefits of improved health outcomes, they need to make an effort to break free of the sedentary lifestyle. If they fail to do so, the negative health effects will continue to worsen, with potentially fatal consequences.