The Impact of Sitting All Day – Part 3 10 Jul 2020
In part 1, I looked at the impact of sitting on your muscles, and in part 2 I started to explore the impact on the rest of your body. In this post I continue to explore the impact of sitting on your circulatory system including your heart.
When sitting for prolonged periods of time, muscles burn less fat and blood flows more sluggishly, allowing fatty acids to more easily clog the heart. In 2012 Ford & Caspersen in their research paper, Sedentary behaviour and cardiovascular disease: a review of prospective studies (International Journal of Epidemiology, Vol 41, No 5 pages 1338 - 1353) showed that the people with the most sedentary time are more than twice as likely to have cardiovascular disease than those with the least.
In 2012 Zedric and Hamilton found that just a few hours sitting suppresses a gene that helps keep your cardiovascular system healthy by controlling inflammation and blood clotting.
T W Zedric & M T Hamilton, 2012 Identification of hemostatic genes expressed in human and rat leg muscles and a novel gene (LPP1/PAP2a) suppressed during prolonged physical inactivity (sitting), Lipids in Health and Disease, Vol 11 see http://www.biomedcentral.com/content/pdf/1476-511X-11-137.pdfCholesterol
Sitting also means that your large postural support muscles are inactive. When active these muscles produce a quite of beneficial molecules. One molecule skeletal muscles produce is an enzyme called lipoprotein lipase - which you can think of as a vacuum cleaner for fats in the blood stream. A study in rats showed that after 24 hours forced inactivity, their lipoprotein lipase acitivity was reduced by 90 - 95%, which led to a 75% drip in the ability of their muscles to remove fats from their bloodstream as will as a significant decrease in "good" (HDL) cholesterol.
L Bay & Mark Hamilton, 2003, Suppression of skeletal muscle lipoprotein lipase activity during physical inactivity: a molecular reason to maintain daily low-intensity activity, Journal of Physiology, Vol 551, No 2 pages 673 - 682.See http://onlinelibrary.wiley.com/doi/10.1113/jphysiol.2003.045591/full