Longevity Briefs: The World’s Deadliest Piece Of Furniture?

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

The problem: Previous studies have reported a peculiar relationship between sitting and death. We all know that physical inactivity is bad for us, but some studies suggest that no matter how much physical activity we do, there’s just something inherently deadly about sitting down. It’s a difficult topic to make sense of, because anyone who is not sitting or lying down is probably exerting themselves physically in some capacity, so of course people who sit more are likely to be less healthy. There’s also a lot of potential for reverse causation: people who have weaker muscles, for example, are likely to spend more time sitting down.

Is sitting itself really the problem, or is it inactivity? One thing that can help us to untangle these factors is a more accurate way of monitoring sitting time and physical activity, and that’s what researchers attempted to apply in this study.

The discovery: Researchers conducted a study with 5856 women with an average (mean) age of 79. Between 2012 and 2014, participants were mailed hip accelerometers to wear for about 7 days. A recently developed neural network algorithm was used to measure the time spent sitting vs low, moderate or intense physical activity. This algorithm was shown to be better at identifying changes in posture and low intensity activity than previous methods, which sometimes misclassified standing or very low levels of physical activity as sedentary behaviour. Researchers then studied how this data correlated with mortality, which was measured up until 2022.

They found that women who spent more total time sitting, as well as those who sat for longer at a time, had higher mortality rates from all causes and from cardiovascular disease. Women who sat for over 11.6 h/d were 57% more likely to die from any cause and 78% more likely to die from cardiovascular disease compared to those who sat for less than 9.3 h/d. This increased risk was independent of physical activity, function and multimorbidity (the presence of multiple long-term health conditions).

The implications: This study presents yet more evidence that time spent sitting may increase your risk of death. The debate over exactly why this is the case will probably continue. Various mechanisms have been proposed to explain the potential inherent dangers of sitting, such as increases in low-level chronic inflammation and changes in blood supply. However, previous studies have argued that any stationary posture (including standing) is detrimental to health and that there is nothing exceptional about sitting – we simply undervalue very low levels of physical activity. Either way, the practical health implications of the research is the same – avoid spending too much time stationary during the day, and try to break up periods of inactivity with brief walks to avoid too much sedentary time in one go.