Be Careful – Don’t Throw the Baby Out with the Bath Water

December 11, 2012 in Exercise, Fitness, Health, Health Claims by Joyce Bunderson

Two separate studies published recently are concluding that the more someone sits the shorter and less robust his or her life may be. The first study that I want to look at was published in full and abstract in the British Journal of Sports Medicine. In essence, the researchers claim that TV viewing time may be associated with a loss of life that is comparable to other major chronic disease risk factors such as physical inactivity and obesity. This study uses quite a bit of extrapolation of data from other studies. There is one sentence in the Results section of the abstract, in which my discomfort found some comfort: This study is limited by the low precision with which the relationship between TV viewing time and mortality is currently known.

In this post I must be somewhat critical of some authors making rather precise predictions based on data that do not support such precision, but I do not want to throw the baby out with the bath water. Sedentary life-styles are getting some real attention by researchers. They are looking at the effects on chronic disease and death of sedentary habits, including hours sitting in front of a TV. This research emphasis is important, and should not be dismissed because some researchers are making predictions using numbers much like the way those taken to hyperbole use words.

The researchers try to correlate a range of a reduction of life expectancy at birth (from 6.8 days to 3.7 years in men and women) to a certain number of hours per lifetime. They say, for every single hour of television viewed after the age of 25 the viewer’s life expectancy is reduced by 21.8 minutes. (It comes from a range of 0.3 to 44.7 minutes; which in itself, seem like a very broad range.) So if you watch TV for an hour you reduce your life expectancy, according to this study, by just under 22 minutes. Yikes, using imprecise numbers with unwarranted precision!!!

The researchers say that TV viewing time may have the adverse health consequences that rival even smoking. “Every single hour of TV watching may shorten life by as much as 22 minutes. They find that smoking one cigarette a day has been estimated at 11 minutes loss in life expectancy. Our findings suggest that half an hour of TV viewing per day above age 25 may shorten life to a similar degree. Now this is alarming, but come on, we’re talking imprecise averages here, with many factors at play for an individual!

The final needed kick in the sedentary pants is that J. Lennert Verrman MD, MPH, PhD the leading researcher in the study says; “a person who does a lot of exercise but watches six hours of TV” every night “might have a similar mortality risk as someone who does not exercise and watches no TV.” This is not so much a defense of the findings of a relationship between TV watching and death, as it is a prediction that sitting trumps exercise and annuls its importance.  Dangerous statement!! Needs studies Verrman did not perform.

I can think of numerous scenarios where the sitting in front of TV seems to fall apart. One that just pops into my mind is the man or woman who has just come in from a long day of building a home; or from harvesting crops; and decides to sit and watch TV or read a book for a little well-deserved relaxation. Do I believe this increases his or her risk of premature death, diabetes, heart health risk? Hummm???

The second study was published in Diabetologia and is a review of 18 studies. This particular study looks at all the hours spent sitting; both TV and sitting at work, driving to work, etc. This second study found an association of sedentary time with diabetes, cardiovascular disease and cardiovascular and all-cause mortality. But they state that the strength of the association is most consistent for diabetes.

Discussing the possible relationship of diabetes to being sedentary makes sense. When we don’t move our large skeletal muscles, which means that they don’t need much fuel, which is the sugar circulating in our blood, that is; it means for some people being sedentary leads to an increase in their risk of diabetes.

What I like about this second study is that the lead researcher Dr. Emma G. Wilmot emphasized, don’t cease exercising. “There is absolutely no doubt that exercise is beneficial for health, it just may not, by itself, be sufficient for health.” She continued, if you exercise for 30 minutes a day, “take time to reflect on your activity levels for the remaining 23.5 hours and aim to be active, sit less.”

So this is where the baby and the bath water come back into the story. Scientific studies sometimes provide fun little statistical games you can play, but remember you really can’t apply these numbers to individuals, at least with a pretended precision that does not exist. Some of the outcomes of the studies are possibly a little weak and meta-analyses are often the subject of lots of criticism. Sometimes the meta-analysis studies are adding apples and oranges. And lastly, they may be generalizing a little too far.

Despite these weaknesses, it makes a lot of sense that sitting all day long and not moving is not a paradigm for healthy living, but we also have to be realistic. Just like changing your diet, maybe you can do something about it gradually, replacing sedentary life styles bit by bit with active ones. Be creative. Think of new ways to move and get off the sofa or develop new interests that involve moving. Can you set a timer and take a short walk every 20 or 30 minutes? Can you stand and move a little whenever you have a phone call? Can you use a standing desk for any part of your work? Some people are even using recumbent bikes and working at the same time. Let your creative juices flow.

Obviously the two studies above need to be replicated, and could use some improvements in design, but it doesn’t mean that we can’t take a ‘heads up alert’ from them. Begin finding ways to move and possibly even increase the intensity, duration and frequency of your exercise.

When I first read the studies, I thought about writers, who spend so many hours sitting. I looked up George Bernard Shaw, a Nobel prize-winning author and discovered that he lived to 94 years old. My guess is that he spent many hours sitting at a desk. Also, I thought of George Burns, who died at 100 with his cigars. It reminds me that longevity is really a relationship of many factors. Yes, we want to reduce risk by eating a healthy diet, by having enjoyable social interactions, moderate or no drinking, no smoking and exercising; but the fact is also that our genetics do have some impact. Whether our telomeres keep serving us for long years or not is influenced by genetics, not just our behaviors and our lifestyle.

So whatever we do, let’s not throw the baby out with the bath water. There is a plethora of strong and credible evidence that exercise is related to a more vigorous and long life, in addition to a reduction in risk of many disease states. So, for now, keep walking, peddling or look for some new forms of exercise for 2013.