A heart attack is the ultimate complication of a disease, which may often remain silent for years before revealing itself in a single, and sometimes deadly event. Heart disease remains the number one cause of deaths worldwide, accounting for more than 15 million deaths in 2015 alone. In comparison, road injuries killed 1.3 million people in the same year (WHO, 2017). According to the American Heart Association, up to 80% of heart disease and strokes are preventable. So, what exactly happens to the heart during an attack?
With every beat, the heart sends a portion of blood through a range of blood vessels in order to nurture and fuel itself. As a powerful muscle in constant action, the heart has a steady demand for oxygen and nutrients.
These rather tiny blood vessels of the heart are called the coronary arteries. With diameters in the millimetre range, the coronary arteries are at a much higher risk of becoming clotted. These clots arise through gradual build-up on the vessel walls until they eventually rupture and a blood clot forms on its surface. As the clot grows, it can become large enough that it blocks circulation to parts of the heart, leading to a heart attack. Comparable blood clots can also form in other damaged blood vessels throughout the body, and if these dislodge and travel to smaller blood vessels, such as in the brain or lungs, it can result in stroke or pulmonary embolism. The underlying process is often the same.
How does a sedentary lifestyle contribute to this pathology? Why is sitting too much becoming even more dangerous to our cardiac health than smoking, as is often cited in current headlines?
In its essence, heart disease can be understood as a metabolic disease, where an unfavourable mixture of biochemicals plaque the blood vessels over an extended period of time. The lack of movement that comes along with being sedentary promotes this unfavourable mix in the blood and body. It can also increase the risk of heart attack or stroke by reducing healthy blood flow, weakening the heart muscle, which in turn raises blood pressure and creates a permanent low-level inflammatory state.
Sedentary behaviour also makes it more likely that a person will gain unhealthy body fat and lose lean muscle mass. As discussed in the last chapter, weight gain can lead to insulin resistance and impair blood glucose regulation, while increasing levels of circulating triglycerides and low-density lipoprotein (LDL) cholesterol. High blood pressure also puts extra strain on the blood vessels and heart, all leading to damage and possible consequent plaque formation. Being physically active helps keep the blood glucose in check and is one of the best things one can do to raise levels of beneficial high-density lipoprotein (HDL) cholesterol, which helps to clear LDL cholesterol from your arteries.
The scientific data from the last ten years or so can easily be distilled to a single message: the more hours somebody spends sitting each day, the higher his or her likelihood for getting diagnosed with some form of heart disease later on in life, regardless of whether the person is otherwise active in his or her leisure time. Here are some of the most impressive data.
In one study looking at almost a quarter of a million adults aged 50-71, those who spent seven or more hours a day sitting, compared to those who sat for less than one hour a day, had an 85% increased risk of death from cardiovascular disease (Matthews et al., 2012). Other studies have shown that people who sit a lot have a much higher risk of high blood pressure (a 71% increase in one study), as well as being 42% more likely to have lower levels of beneficial high-density lipoprotein (HDL) cholesterol (Park et al., 2018). Interestingly, this study also found that no amount of intense exercise was able to make up for all that sitting: people who spent seven or more hours a day sitting also had twice the risk of death from cardiovascular disease, even if they also spent one or more hours a day exercising (Matthews et al., 2012). Statistically, for every two hours a person spent sitting each day, the risk for cardiovascular disease increases by an additional 5% (Ford & Casperson, 2012).
Once affected by a heart attack or another cardiac disease, patients often have a significantly reduced quality of life, experiencing associated symptoms such as shortness of breath, fatigue and reduced physical capacity, making exercise increasingly difficult and resulting in more hours spent sedentary.
On the other hand, for a long time cardiologists have proclaimed that long-term low to moderate physical activity (such as walking) appears to have an overall favourable effect on one’s cardiovascular health.
One of the largest studies looked at more than a million people and compared their walking behaviour with their risk of being diagnosed with heart disease. It seems as though walking can have miraculous effects on the heart. People who walked around an hour each day or around 20km per week could lower their heart risk by almost a third (Hamer & Chida, 2014). That is better than what so many medications on the market could ever hope to provide, and instead of side effects, walking comes with side benefits! Other studies have pointed to similarly promising findings. Simply incorporating daily walking time led to a 29% lowered risk of hypertension in over 6,000 Japanese men (Hayashi et al., 1999), and a 27% lowered mortality rate in 2,000 Americans with just four hours of walking per week (LaCroix et al., 1996).
About the Author
Walkolution develops ergonomically optimized treadmill desks, which help to bring more movement into the daily work routine in the office or home office.
Photo credit: Jesse Orico