Exercise can buffer the effects of stress-induced cell aging, according to new research from UCSF that reveals actual benefits of physical activity at the cellular level. The scientists learned that vigorous physical activity as brief as 42 minutes over a three-day period, similar to federally recommended levels, can protect individuals from the effects of stress by reducing its impact on telomere length. Telomeres (pronounced TEEL-oh-meres) are tiny pieces of DNA that promote genetic stability and act as protective sheaths by keeping chromosomes from unraveling, much like plastic tips at the ends of shoelaces.