There is valid concern about diversity and inclusiveness in research participants, and in the disparity in the severity and age of onset for cardiovascular disease among African Americans. With those two factors as motivation, and of course, the continuing need to publish or perish, a new study in the Journal of the American Heart Association points to the health impact of television watching on African Americans. But beyond the ability of the study to provide a snarky title, it offers little to improve care.
Researchers made use of a population-based study of cardiovascular disease among African-Americans  which among other factors considered sedentary behavior, physical activity, and television viewing – all captured by surveys. The outcome, the standard composite measure of coronary heart disease, stroke, and all-cause mortality. Roughly 3600 participants were followed for a median of 8.4 years, with 129 coronary or stroke events, and 205 deaths.
- Watching >4 hours of television a day was associated with an 80% increased risk of coronary heart disease, stroke, or death compared to watching < 2 hours.
- Sitting, while at work, on the other hand, was associated with a 30% decreased risk of coronary heart disease, stroke, or death.
- Both patterns were maintained when the composite’s components were considered separately.
- Ideal physical activity  moderated the influence of television watching, resulting in risk-free television watching.
Before shutting off your television as a physical (and probably mental) deathtrap, you should know that those participants who watched 4 hours or more of television a day were different than those watching 2 hours a day. More specifically, they drank twice as much, smoked twice as much, were heavier, with a more deficient diet (based on the AHA preferred diet), and were more sedentary in general. Not an apple to apple comparison. And those participants who were more sedentary at work had more leisure time physical activity, a healthier diet and were less likely to smoke or drink heavily. Again, not a valid comparison to isolate the effect of television viewing.
The researchers suggest that an “association between sedentary behavior and risk of CVD/all-cause mortality in African-Americans differs for leisure and non-leisure types of sedentary behavior. Our results furthermore reveal that high levels of [physical activity] eliminated the increased risk of CVD events and all-cause mortality associated with high TV viewing time, underscoring the benefits of physical activity for African Americans.” TV viewing is associated with other behaviors that harmfully impact your health; there is no news there.
CVD does have a disproportionate impact on African Americans, and it is essential to understand why that might be. But is there a reason to believe that African Americans have some significant physiologic difference that would make them more or less likely to succumb to the watching television?
“Further research is needed to determine the levels of physical activity needed to modify the deleterious health effects of TV viewing.”
There it is, the holy grail; if we could determine how much exercise is needed to balance out television viewing, we could medicalize the problem, providing dosages to treat. You wouldn’t have to stop watching television, you would just have to do the right amount of exercise, and the health accounts would be equalized. Perhaps jumping to unwarranted conclusions could be considered moderate physical activity? This kind of thinking is best characterized by Nassim Taleb when he pointed out how many people who lift weights in the gym still required someone to carry their bags at the airport or hotel.
 The Jackson Heart Study named for Jackson Mississippi involving adult volunteers between 2000 and 2004 with follow up examinations in 2008 and 2012.
 More than 75 minutes/week of vigorous physical activity or 150 minutes/week of moderate-vigorous activity. Moderate exercise includes activities like ballroom dancing, gardening, walking 2.5 miles/hour, where “your heart will beat faster, and you’ll breathe harder than normal, but you’ll still be able to talk.” Vigorous activity includes running, hiking with a heavy backpack, swimming laps, where you “will require a higher amount of effort. You’ll probably get warm and begin to sweat. You won’t be able to talk much without getting out of breath.”
Source: Types of Sedentary Behavior and Risk of Cardiovascular Events and Mortality in African-Americans Journal of the American Heart Association DOI: 10.1161/JAHA.118.010406