Scientists from the University of Birmingham investigated bikers aged 55 to 79 who ride their bikes for many hours each day. These researchers discovered that cycling in old age keeps muscle mass and strength from deteriorating. And the fat and cholesterol levels remained constant. However, the most incredible discovery is that cyclists' systems generate immunological T-cells in equal numbers to 20-year-olds. It's incredible since T-cell production begins to decline around the age of 20. This demonstrates that riding a bicycle makes the immune system younger.