Inactivity may increase mortality and disease risk
By David Dunaief, M.D.
With the advent of summer weather, with its heat and humidity, who wants to think about exercise? Instead, it’s tempting to lounge by the pool or even inside with air conditioning.
First, let me delineate between exercise and inactivity; they are not complete opposites. When we consider exercise, studies tend to focus on moderate to intense activity. However, light activity and being sedentary, or inactive, tend to get clumped together. But there are differences between light activity and inactivity.
Light activity may involve cooking, writing and strolling (1). Inactivity involves sitting, as in watching TV or in front of a computer screen. Inactivity utilizes between 1 and 1.5 metabolic equivalent units — better known as METS — a way of measuring energy. Light activity, however, requires greater than 1.5 METS. Thus, in order to avoid inactivity, we don’t have to exercise in the dreaded heat. We need to increase our movement.
What are the potential costs of inactivity? According to the World Health Organization, over 3 million people die annually from inactivity. This ranks inactivity in the top five of potential underlying mortality causes (2).
How much time do we spend inactive? In an observational study of over 7,000 women with a mean age of 71 years old, 9.7 waking hours were spent inactive or sedentary. These women wore an accelerometer to measure movements. Interestingly, as body mass index and age increased, the amount of time spent sedentary also increased (3).
Inactivity may increase the risk of mortality and plays a role in increasing risks for diseases such as heart disease, diabetes and fibromyalgia. It can also increase the risk of disability in older adults.
Surprisingly, inactivity may be worse for us than smoking and obesity. For example, there can be a doubling of the risk for diabetes in those who sit for long periods of time, compared to those who sit the least (4).
Let’s look at the evidence.
Does exercise overcome inactivity?
We tend to think that exercise trumps all; if you exercise, you can eat what you want and, by definition, you’re not sedentary. Right? Not exactly. Diet is important, and you can still be sedentary, even if you exercise. In a meta-analysis — a group of 47 studies — results show that there is an increased risk of all-cause mortality with inactivity, even in those who exercised (5). In other words, even if you exercise, you can’t sit for the rest of the day. The risk for all-cause mortality was 24 percent overall.
However, those who exercised saw a blunted effect with all-cause mortality, making it significantly lower than those who were inactive and did very little exercise: 16 percent versus 46 percent increased risk of all-cause mortality. So, it isn’t that exercise is not important, it just may not be enough to reduce the risk of all-cause mortality if you are inactive for a significant part of the rest of the day.
Worse than obesity?
Obesity is a massive problem in this country; it has been declared a disease, itself, and it also contributes to other chronic diseases. But would you believe that inactivity has more of an impact than even obesity? In an observational study, using data from the EPIC trial, inactivity might be responsible for two times as many premature deaths as obesity (6). This was a study involving 330,000 men and women.
Interestingly, the researchers created an index that combined occupational activity with recreational activity. They found that the greatest reduction in premature deaths (in the range of 16 to 30 percent) was between two groups, the normal weight and moderately inactive group versus the normal weight and completely inactive group. The latter was defined as those having a desk job with no additional physical activity. To go from the completely inactive to moderately inactive, all it took, according to the study, was 20 minutes of brisk walking on a daily basis.
So what have we learned about inactivity? If you are inactive, increasing your activity to be moderately inactive by briskly walking for 20 minutes a day may reduce your risk of premature death significantly. Even if you exercise the recommended 150 minutes a week, but are inactive the rest of the day, you may still be at risk for cardiovascular disease. You can potentially further reduce your risk of cardiovascular disease by increasing your activity with small additions throughout the day.
The underlying message is that we need to consciously move throughout the day, whether at work with a walk during lunch or at home with recreational activity. Those with desk jobs need to be most attuned to opportunities to increase activity. Simply setting a timer and standing or walking every 30 to 45 minutes may increase your activity levels and possibly reduce your risk.
(1) Exerc Sport Sci Rev. 2008;36(4):173-178. (2) WHO report: https://bit.ly/1z7TBAF. (3) JAMA. 2013;310(23):2562-2563. (4) Diabetologia 2012; 55:2895-2905. (5) Ann Intern Med. 2015;162:123-132, 146-147. (6) Am J Clin Nutr. online Jan. 24, 2015.
Dr. Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, visit www.medicalcompassmd.com or consult your personal physician.