Researchers say regular exercise may help reduce the health risks associated with prolonged sitting.
Numerous studies have suggested that sitting for long periods has negative health implications and may raise the risk of all-cause mortality.
Last month, Medical News Today reported on a study that linked prolonged sitting to increased risk of nonalcoholic fatty liver disease, while another study associated longer sitting times with greater risk of breast and ovarian cancers.
What is more, previous research claims such risks may not be offset by physical activity. Earlier this year, a study published in the Annals of Internal Medicine suggested that even an hour of exercise daily may not lower the disease risks associated with sedentary behavior.
However, this latest study - led by Dr. Richard Pulsford of the University of Exeter in the UK - challenges such findings, claiming that prolonged sitting does not increase mortality risk among people who are otherwise physically active.
Their findings are published in the International Journal of Epidemiology.
'Problem lies in the absence of movement rather than sitting time'
Dr. Pulsford and colleagues analyzed data from 3,720 men and 1,412 women who were part of the Whitehall II cohort study - a longitudinal study of British Civil Service employees - and who were free of cardiovascular disease.
- Current guidelines state adults should engage in 70 minutes of vigorous-intensity physical activity or 150 minutes of moderate-intensity activity each week
- However, only around 1 in 5 adults in the US meet these guidelines
- Inactive adults are at increased risk of stroke, heart disease, type 2 diabetes and cancer.
Between 1997-99, all participants were asked how many hours each week they spent sitting in total, as well as how many hours they spent sitting each week while at work, during leisure time, while watching TV and during leisure time excluding watching TV.
Participants were also asked how much time they spent engaging in moderate to vigorous activity each day, and information on their daily walking time was gathered.
The researchers followed the participants for an average of 16 years, until July 31st, 2014, or until death. A total of 450 deaths were recorded during follow-up.
The results of the study revealed that the total amount of time spent sitting - and the amount of time spent sitting at work, while watching TV and during leisure time with or without TV - was not associated with the risk of all-cause mortality.
This finding remained even after the team accounted for participants' age, gender, socioeconomic status, smoking status, alcohol consumption, diet and general health.
The team says the lack of association between prolonged sitting and all-cause mortality may partly be down to the protective effect of daily moderate to vigorous physical activity - levels of which were higher than average in this cohort.
Study coauthor Dr. Melvyn Hillsdon, of the University of Exeter, says the study results indicate that policymakers should be cautious about recommending a reduction in sedentary behavior without promoting physical activity. He adds:
"Our study overturns current thinking on the health risks of sitting and indicates that the problem lies in the absence of movement rather than the time spent sitting itself. Any stationary posture where energy expenditure is low may be detrimental to health, be it sitting or standing."
What is more, Dr. Hillsdon says the findings "cast doubt" on the benefits of sit-stand desks in the workplace - something researchers of a recent study reported by MNT claim could be "part of a larger health plan" to tackle the health risks of prolonged sitting at work.
The team says further research is warranted to investigate whether prolonged sitting is linked to greater risk of certain diseases, such as heart disease and type 2 diabetes, as well as to determine the biological mechanisms behind previously established associations between sitting time and poor health.