Too Much Sitting, Too Little Exercise

The importance of physical activity in managing cardiovascular disease

Physical activity is defined as any bodily movement produced by skeletal muscles that requires energy. According to the World Health Organisation, physical inactivity has been identified as the fourth leading risk factor for global mortality, causing an estimated 3.2 million deaths worldwide. Physical activity is a modifiable risk factor for cardiovascular disease. There is strong evidence to show that moderate to vigorously intense physical activities plays a key role in preventing cardiovascular disease by targeting risk factors such as type 2 diabetes, hypertension and obesity.

The benefits of physical activity also extend to patients with existing cardiovascular disease. In the past, rest and reduced activity have been recommended for patients with heart disease. However, this is no longer advocated.

Fact sheet of how sitting is bad 

  • People with sitting jobs have twice the risk of cardiovascular disease compared to those with standing jobs
  • Fat burning drops drastically to 1 calorie per min the moment we sit
  • Every 2 hours spent just sitting reduces blood flow, raises blood glucose and drops good cholesterol by 20%
  • Watching television for 6 hours a day takes away 5 years off your life
  • Walking burns 3-5 times more calories that sitting does. Take every opportunity to walk around the office
  • Interrupt sitting whenever you can

In recent studies, strong evidence has shown the importance of engaging in regular exercise to attenuate or reverse the disease process in patients with cardiovascular disease; for example, slowing down the progression of coronary artery disease. The recent physical activity and health recommendations from the American College of Sports Medicine and the American Heart Association continue to stress the importance of participating in at least 30 minutes of moderate intensity physical activity or 20 minutes of vigorous-intensity physical activity for at least 5 days a week, accumulating a minimum of 150 minutes a week. This is applied in addition to the light activities of daily living such as standing, walking slowly and lifting objects.

The Sitting Disease

With advances made in the modern world, the need to be active is significantly reduced. People can now spend the majority of their waking day in a chair watching television, working at a desk, ordering and receiving items in the comfort of their homes such as take-out and online shopping etc.. There are many forms of locomotion that rid the need for walking.

A study by the Singapore Heart Foundation in 2010 revealed that only 19% of adults aged 18 to 69 years exercise regularly and more than half of Singapore residents do not exercise during their leisure time. Although the human body is made to be in frequent motion, people can sit for many hours at a time, day after day.

Sedentary behaviour has been the new focus for research in physical activity and health. This phrase ‘sedentary behaviour’, originates with the Latin word “sedere” which means “to sit”. Sedentary behaviour is defined by their posture (sitting or reclining) and their low energy expenditure – typically at least three times lower than moderate-intensity activities such as brisk walking.

Recent studies have shown that time spent in sitting have an independent impact on increasing cardiovascular risk factors namely obesity, lipids and type 2 diabetes. One of the most striking findings in these studies is that these negative effects of prolonged sitting also apply to those who fulfil the criteria of 30 minutes of physical activity daily but spend the majority of their day sitting. This highlights that physical activity does not cancel out the ill effects of too much sitting during the day. These effects are further magnified in people who do not exercise and remain sedentary for most of their day. The highest mortality risk is seen with people who are obese.

So how much sitting, is ‘too much’?

According to a US survey, at least half, and up to two thirds of an adult’s waking hours are spent sedentary which range from 6-10 hours a day. Prolonged sitting has an impact on mortality and life expectancy. Too much sitting impairs the body’s ability to deposit fat from the blood stream into the body. In addition, it is observed that too much sitting during the day impairs the functioning of the body’s good cholesterol, known as high-density lipoprotein (HDL) which is responsible for cleaning up plaque that sticks to arteries. In a nutshell, the more you sit, the higher the risk of increasing your systolic blood pressure, waist circumference, blood glucose and triglycerides even if you adhere to the recommendation of 30 minutes of moderate-intensity physical activity a day.

All studies are indicating that moving more during the day, in addition to getting the daily 30 minutes of moderate activity on a daily basis, is necessary to lower one’s risk of cardiovascular disease and other causes of mortality.

The Remedy: Stand up, sit less, move more, more often

Now that we know that sitting increases cardiovascular disease risk factors and reduces length of life, how can we turn things around?

This is especially important for people who are in occupations which involve prolonged sitting. For example: office workers, transport drivers and those who have to sit due to musculoskeletal disorders like osteoarthritis which can be a barrier to participation in moderately intense activity as well. The key here is breaking up sedentary time with light activities such as standing and normal paced walking.

Studies have shown that insulin action improves with more standing time and stepping time. The effects of light activity compared to moderate activity is shown in another study. Sitting interrupted by a short 2-minute bout of walking showed similar, significant reductions in post-meal glucose and insulin. These short breaks suggest that light activity plays a beneficial role in reducing the adverse effects of prolonged sitting, compared to having no interruptions at all.

The importance of regular moderately vigorous exercise should continue to be emphasised in the prevention and treatment of cardiovascular disease. At this stage, everyone is encouraged to create opportunities to limit your sitting time at home, at work and during transportation and break-up long periods of sitting through frequent transitions from sitting to standing to walking as much as possible throughout the day. The key to minimising cardiovascular disease is: ‘stand up, sit less, move more, more often’.

The following information may be useful in offering you practical suggestions in reducing sitting time throughout the day, as well as through a 5-minute desk workout.

If you are above the age of 40, or have any existing medical conditions, or recently been inactive or concerned about your health, it is advisable for you to consult a doctor before starting on any moderate-vigorous intensity physical activity.

Not all exercise programmes are suitable for everyone, and some programmes may result in injury. Activities should be carried out at a pace that is comfortable for the user. Users should discontinue participation in any exercise activity that causes pain or discomfort. In such event, please seek medical consultation immediately.

 

Ms Jaclyn Chow is a Senior Physiotherapist with Tan Tock Seng Hospital. She was awarded the Bachelor in Health Science (Physiotherapy) from Trinity College Dublin in 2013. Ms Chow has a special interest in Cardiac and Pulmonary Rehabilitation and has been working in both the inpatient and outpatient settings.