With the advancement of delivery technologies like UberEats and Grocery Gateway, as well as the increase in people’s ability to work from home, many of us can obtain our basic needs while seated almost all day, every day.
Thus it likely won’t come as a surprise to hear that the average Canadian between the ages of 18 to 79 years sits for 9.8 hours per day, which is 1.8 hours above what the Canadian 24-Hour Movement Guidelines recommend for most adults.
Sedentary behaviour and its associations with poor mental and physical health have been heavily reported in high-income countries. However, less research has focused on sedentary behaviours in low- to middle-income countries, even though sitting behaviours, such as watching TV, are more common among people from lower socioeconomic positions. This may be owing to recreational physical activities being more costly while recreational sedentary activities, such as watching TV, are generally less expensive.
For this reason, a team of researchers from around the globe wanted to explore the associations of self-reported sitting time and physical activity levels on people’s risk of mortality and major cardiovascular disease across countries with varying income levels. The team was led by Sidong Li, BM, from the Chinese Academy of Medical Sciences and Peking Union Medical College, alongside some Canadian researchers including Scott Lear, PhD, from Simon Fraser University and Sumathy Rangarajan, MSc, from the Population Health Research Institute and McMaster University. This study was published in JAMA Cardiology.
The study comprised over 100,000 participants between 35 and 70 years old from 21 countries on five continents. Data on sitting time and physical activity levels were taken at baseline and 11 years later the same participants’ health statuses were recorded. For example, the survey asked whether the participants were in good health, whether they’d experienced a stroke, or the cause of their death, where relevant.
Are sedentary behaviour and income levels linked?
The researchers found that across all participants, regardless of income level, more hours of sitting per day was associated with a higher risk of mortality and cardiovascular disease. However, when separating participants by geographical region, eight hours or more of sitting was associated with a higher risk of mortality and cardiovascular disease in all regions assessed except North America and Europe, typically higher-income countries.
This suggests that lower-middle-income and lower-income countries may be at a slightly greater risk of death or heart disease due to excessive hours of sitting every day compared to upper-middle-income and higher-income countries. This may be due to more time spent watching TV, less access to education, or less access to nutritional food, impeding lower-middle-income and lower-income citizens from having the energy to be active compared to citizens from higher-income countries.
Does physical activity counteract the amount of sitting?
Participants who only had 150 minutes of moderate to vigorous physical activity per week had a higher risk of mortality and major cardiovascular disease across all income levels.
Surprisingly, participants who participated in moderate to vigorous physical activity (150 to 750 minutes per week) but sat for eight hours or more per day, had a higher risk of mortality and cardiovascular disease compared to those who participated in 150 minutes of physical activity per week but sat for four hours or less per day. This suggests that increasing physical activity levels to counteract excessive sitting time per day may not benefit physical health as much as some might believe.
Further, the researchers demonstrated that if participants who sat for four hours or more a day replaced 30 minutes of this time with physical activity, there was a 2% decrease in their risk of mortality and cardiovascular disease. This effect was greater if participants carried out recreational physical activity, such as organized sports, over non-recreational physical activity, such as physical labour.
Where to go from here
Findings from this study will hopefully push public health policies in lower-income countries to create programs or build facilities that offer inexpensive recreational physical activities. Based on the results from Li and colleagues, access to recreational physical activities for people from all income backgrounds will likely decrease risk of mortality and cardiovascular diseases across the globe.
Although the exact amount of time recommended to sit per day warrants future research and may need to be tailored to be country-income specific, it is clear that sitting less (around four hours per day or less) and moving more (around 750 minutes per week or more) can positively impact our present and future physical health.