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Hours of gaming, binge-watching your favourite OTT show or sitting in front of a computer without getting up may seem harmless. But prolonged, uninterrupted sitting can slow blood flow in the legs and potentially increase the risk of a blood clot forming in a deep vein, usually in the leg.
If part of the clot breaks away, it can travel through the veins to the right side of the heart and then enter the arteries supplying the lungs. This can block blood flow and cause a potentially life-threatening condition called a pulmonary embolism.
How Much Sitting On A Daily Basis Impacts Health?
A systematic review published in 2021 in the International Journal of Environmental Research and Public Health found that South Asian adults spent an average of approximately seven hours a day in sedentary behaviour. Studies using activity monitors recorded an even higher average of nearly nine hours a day.
The findings suggest that sitting occupies a substantial part of our waking lives, from working at a desk and commuting to watching television and scrolling on our phones. However, these estimates are based on a limited number of studies and should not be treated as a definitive national average for India.
Why Are Doctors Worried?
When you sit still for hours, your calf muscles remain relatively inactive. These muscles act as a pump, helping blood travel from the legs back towards the heart. When this pumping action reduces, blood flow can slow down.
A 2024 systematic review and dose-response meta-analysis published in Scientific Reports, covering 31 studies, found that people with the highest levels of sedentary behaviour had approximately 24% higher risk of venous thromboembolism (blood clots in veins) than those with the lowest levels. The analysis also reported an approximately 2% increase in risk for every additional hour of sedentary behaviour per day.
These findings show an association, not proof that screen time directly causes blood clots. The risk can be greater when prolonged inactivity occurs alongside factors such as obesity, smoking, hormonal medication, inherited clotting disorders or a previous history of blood clots.
"When a young person sits continuously for four, five or six hours playing games or binge-watching OTT content, the calf muscles are barely working as a pump for venous blood," says Dr Tapish Sahu, Director and Head of Vascular and Endovascular Surgery at Max Hospital, New Delhi.
"A young age should not create a false sense of security, particularly when prolonged sitting is combined with other risk factors." says Dr Tarun Grover, Senior Director of Peripheral Vascular and Endovascular Sciences at Medanta.
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Can Simple Calf Raises Help?
Yes. Calf raises activate the calf muscles and help support the return of blood from the legs towards the heart.
Stand with your feet hip-width apart, hold a chair or wall for balance if necessary, lift your heels until you are standing on your toes, and slowly lower them. Repeat several times, as comfortable. If you cannot stand, seated heel raises and ankle pumps are alternatives.
Calf raises are a useful way to introduce movement, but they are not a guaranteed way to prevent blood clots.
"If you are going to spend hours on a screen, do not spend those hours completely still," says Dr Bhupesh Garg, Senior Vascular and Endovascular Surgeon at the Vascular Society of India.
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Disclaimer: This content including advice provides generic information only. It is in no way a substitute for a qualified medical opinion. Always consult a specialist or your own doctor for more information. NDTV does not claim responsibility for this information.