Fast walking takes years off your age, new research indicates. Scientists had already shown that a quick walking speed was a very strong predictor of longevity. They have now found evidence that that a brisk pace causes an increase in leucocyte telomere length – a measure of your biological age. Telomeres are DNA-protein complexes that protect the ends of chromosomes from damage. Researchers defined a brisk pace as more than 4 miles per hour and slow as less than 3 miles per hour.