One particular study, published in 2018, shows the importance of exercise to the immune system and longevity. The study looked at the immune systems of people aged fifty-five to seventy-nine, comparing more sedentary people with regular cyclists. The people who exercised showed several crucial differences in their elegant defenses: The cyclists produced more new T cells from the thymus, and they had fewer cytokines that cause the thymus to decay. The upshot of the research is that exercise slows the natural aging process of the immune system.
