Researchers at King's College in London, England, studied a group of 125 adults (84 males, 41 females) aged 55 to 79, cycling for at least two and a half hours per week for several years. None of them smoked, consumed alcohol regularly or suffered from hypertension.

Specifically, the selected men were able to cover 100 km in less than 6.5 hours while women could travel 60 km in less than 5.5 hours.
T cells, little soldiers of the immune system

Their health status was compared to that of 75 adults aged 57 to 80, as well as 55 healthy young people aged 20 to 36, who did not exercise regularly. To do this, the researchers focused their attention on the thymus, an organ located in the upper chest playing a very important role in the education of the immune system in children by maturing certain white blood cells, lymphocytes T. With age, the thymus atrophies, leading to a decline in the functioning of the immune system. This is why older people are more fragile and more prone than young people to develop diseases.
"The immune system of a person of 20 years"

As a result, during their study, researchers found that T-cell levels were higher and freshly manufactured in older sports people than their sedentary counterparts. These levels were even more or less equal to those of the young adult cohort. These results suggest that by practicing a regular sport activity, we play a role on our own immune system.