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According to a study published in the British Journal of Sports Medicine, engaging in just 20-25 minutes of daily physical activity can counteract the heightened risk of death associated with a sedentary lifestyle. The research indicates that even higher levels of daily physical activity are linked to a reduced risk, regardless of the amount of time spent sitting each day.
In developed nations, adults typically spend around 9 to 10 hours per day sitting, primarily during working hours. This sedentary lifestyle is correlated with an increased risk of mortality, as explained by the researchers. Previous research on the benefits of physical activity in counteracting prolonged sitting has often relied on aggregated data, resulting in a generalized approach.
To address this, the researchers compiled individual participant data from four groups equipped with activity trackers to examine whether physical activity could modify the association between sedentary time and mortality, and vice versa. They also investigated the levels of physical activity and sitting time that might influence this risk.
The study included data from participants collected between 2003 and 2019 from the Norwegian Tromso Study 2015-16, the Swedish Healthy Ageing Initiative (HAI) 2012-19, the Norwegian National Physical Activity Survey (NNPAS) 2008-09, and the US National Health and Nutrition Examination Survey (NHANES) 2003-06. The analysis encompassed nearly 12,000 individuals aged 50 and above, who had a minimum of 4 days with 10 daily hours of activity tracker records, were monitored for at least 2 years, and provided details about factors like sex, education, weight, height, smoking history, alcohol intake, and any history of cardiovascular disease, cancer, or diabetes.
Among them, 5943 people spent less than 10.5 hours sitting daily, while 6042 logged 10.5 hours or more of sedentary time. Analysis of death records over an average 5-year period revealed that 805 (7%) individuals passed away, of which 357 (6%) had less than 10.5 hours of daily sitting, and 448 had 10.5 hours or more.
The study found that being sedentary for over 12 hours a day was linked with a 38% higher risk of death compared to those who were sedentary for 8 hours, but only among those who engaged in less than 22 minutes of moderate to vigorous physical activity per day. More than 22 minutes of such activity correlated with a lower risk of death.
While a greater amount of moderate to vigorous physical activity was associated with a lower mortality risk, regardless of sedentary time, the influence of sedentary time on mortality was largely determined by the amount of moderate to vigorous physical activity. For instance, an extra 10 minutes of such activity per day was linked with a 15% lower risk of death for those sitting fewer than 10.5 hours, and a 35% lower risk for those sitting more.
Light intensity physical activity only showed a reduced risk of death among those with highly sedentary habits (12+ hours daily). It’s important to note that this study is observational, meaning it cannot establish cause and effect. Additionally, the researchers acknowledge limitations, such as the inability to track changes in physical activity and sedentary hours over time, and not accounting for factors like diet, mobility issues, and general health. Activity trackers may also not accurately classify all types of activity and their corresponding intensity, such as cycling, resistance exercises, and gardening.
Nonetheless, the researchers conclude that even small amounts of moderate to vigorous physical activity may be an effective strategy to mitigate the mortality risk associated with high sedentary time. Accumulating more than 22 minutes of such activity completely eliminates the risk of prolonged sedentary behavior. They suggest that efforts to promote physical activity can yield significant health benefits for individuals.
