“People who regularly run or walk briskly appear to have healthier discs in their spines than people who do not exercise, according to one of the first studies to closely examine links between movement and disc health.”
Researchers are currently investigating whether the opposite of what we have heard for years about running putting too much stress on your back may be true.
Please see the above article on why Running may actually good for your back in addition to the many other cardiovascular benefits.
Link to article here.