Exercise is another important way of preventing early telomere shortening. Researchers in Germany looked at telomere length in four groups of people: those who were young and sedentary, those who were young and active, those who were middle-aged and sedentary, and those who were middle-aged and active. There wasn’t much of a difference between the two groups of young people, but when the participants were middle-aged, the change in telomere lengths was striking. The sedentary middle-aged folks had telomeres that were 40% shorter than the young people, while the active middle-aged folks had telomeres that were only 10 percent shorter than the young people. In other words, the active group reduced their telomere shortening by 75 percent.1 Exercise significantly reduces perceived stress levels and inflammation,2 which may help to explain these results.

• 1. Gretchen Reynolds, “Phys Ed: How Exercising Keeps Your Cells Young,” New York Times Well, January 27, 2010, https://well.blogs.nytimes.com/2010/01/27/phys-ed-how-exercising-keeps-your-cells-young/?scp=1&sq=how%20exercising%20keeps%20your%20cells%20young&st=cse.

• 2. Angela R. Starkweather, “The Effects of Exercise on Perceived Stress and IL-6 Levels Among Older Adults,” Biological Research for Nursing 8, no. 3 (January 2007): 186–94, https://www.ncbi.nlm.nih.gov/pubmed/17172317.