In a new study published in May, U.S. researchers reported that men who sit the most have the greatest risk of heart problems: those who spend over 23 hours per week watching TV and sitting in their cars have a 64 per cent greater chance of dying from heart disease than those who sat for 11 hour per week or less. While these results were unsurprising, many men who suffered health problems after being sedentary for long hours also exercised, and reported leading active lifestyles, the New York Times reports. On average, adults now spend more than nine hours a day being sedentary. Before computers and TVs became widespread, people spent more time on “light-intensity activities,” like mopping, cooking and changing lightbulbs, hours that have been replaced with sitting. In a number of recent studies, animals who kept still in their cages developed unhealthy cellular changes in their muscles, showing signs of insulin resistance and higher levels of fatty acid in the blood. Muscles change when unused, upping the risk for heart disease and diabetes.