About one in three people 15 years and above globally does not exercise enough – yet, we acknowledge that insufficient exercise is responsible for about 3.2 million deaths annually. The world has progressively observed a decrease in the level of physical activity among adults. More people live a sedentary lifestyle than ever: they walk less and indulge in few aerobic exercises. Only a few do some muscle training. Globally, people spend more time on their phone screens, watch more television, and sit longer than usual – both at home and work.
A sedentary lifestyle confers no health benefits: it leads to poor health outcomes. It increases the probability of dying from any cause. It potentiates the risk of suffering from cardiovascular diseases like myocardial infarction (heart attack), stroke, and hypertension. Moreover, a sedentary lifestyle and limited physical activity aggravate the risks of developing obesity, abnormal lipid levels, diabetes mellitus, and cancer. In today’s article, we highlight the effects of sedentary behaviours and inadequate physical activity on health. We aim to increase awareness about the need to exercise more, sit and watch less television.
We consider any behaviour a person partakes while awake that leads to an energy expenditure of 1.5 metabolic equivalents of task (MET) or less as a sedentary lifestyle. Such behaviours include watching television, playing video games, sitting at school or work, and sitting during commuting. For simplicity, the ratio of the energy a person spends while exercising to the standard while resting defines MET. By convention, a resting person spends 1 Kilocalorie per kilogram per hour. So, one MET is the energy cost while at rest. Sedentary behaviours provide only 1.0 – 1.5 METs; light physical activities accumulate 1.6 – 2.9 METs; moderate-intensity activities confer 3 – 5.9 METs, while vigorous exercises generate six or more METs.
Several studies have shown that a sedentary lifestyle potentiates the risk of death from any cause. It increases the probability of suffering from cardiovascular diseases, cancer, hypertension, and diabetes mellitus. The cancers, in particular, include breast, colon, endometrial, and ovarian cancer.
The human body undergoes derangements in processing the various nutrients when a person lives a sedentary lifestyle. Such derangements lead to an increase in bad cholesterol (low-density lipoprotein cholesterol) levels, waxy fats (triglycerides), and a reduction in good cholesterol (high-density lipoprotein cholesterol) levels.
An increase in bad cholesterol may reduce the body cells’ sensitivity to insulin (the hormone that dictates how the body utilises glucose). Once the cells are less sensitive to insulin, they become less efficient in metabolising the glucose you’ve consumed. The result? High blood sugars, then diabetes mellitus.
When a person does not adequately exercise, their bones weaken. In other words, their bone mineral density reduces. Such a person is likely to sustain a fracture easily compared to their counterparts who exercise.
Spending more time resting – sitting or watching television reduces the amount of energy the body needs to stay afloat; that is, a person uses less and less of the foods they have consumed. When the body’s metabolic requirements reduce, the blood flow around the body also decreases. In addition, a prolonged sedentary lifestyle activates the sympathetic nervous system – a division of the autonomic nervous system that prepares the body for ‘fight or flight’. It thus reduces the sensitivity of the body cells to insulin and increases vascular tone. Besides, it also increases the formation of oxygen free radicals that eventually underlie salient inflammation throughout the body. All these events are catastrophic precursors to developing high blood pressure (hypertension).
Prolonged sitting at home or work, and television watching, reduces energy expenditure so, the body stores all the excess energy. Usually, the body stores it in the form of fats. It then dumps them around the waist and abdomen. The person gains weight that eventually culminates in obesity.
Obesity increases resistance to blood flow, which piles pressure onto the heart. In turn, the heart grows more muscle (hypertrophies) to counteract the peripheral resistance. It increases the power at which it pumps out blood. Prolonged peripheral vascular resistance leads to hypertension. The person then develops cardiovascular diseases that may lead to heart failure.
The unchallenged increase in body fats dysregulates the production of sex hormones and markers of inflammation. Both increase the risk of diabetes mellitus and cancer, especially hormonal-related cancers like breast, endometrial, and ovarian cancers. A prolonged sedentary lifestyle alone potentiates the risk of colon, colorectal, and prostate cancer.
Finally, a person is likely to suffer from depression and have markedly low cognitive function if they live a more sedentary lifestyle. Such a person will spend most of the time alone, with minimal to no social interaction and limited physical activity. It is prudent to note that mentally active sedentary behaviours like knitting, sewing, book reading reverse the depression risk.
That said, there’s no good in spending most of a person’s time sitting, leaning, or watching television, or perhaps glaring on your phone’s screen. A person who indulges in a sedentary lifestyle of a certain magnitude increases the chances of suffering catastrophic health outcomes, such as obesity, diabetes mellitus, hypertension, and cardiovascular diseases. People must increase their physical activity time to reverse some of the effects of a sedentary lifestyle. Healthy living involves a proper diet coupled with increased levels of physical activity.
For more information about this topic, read this article.