Running is a great cardiovascular sport but it can play havoc on the feet and the back. The main reasons are usually wrong footwear or wrong posture while running. 

Inappropriate running shoes that do not absorb the impact of your feet hitting the road can cause a jarring effect on the vertebrae of the spine and knee joints, indirectly.

Your back pain can also be due to one or more herniated discs or muscle strains which can be aggravated further while running. Proper running shoes from renown brands that have put research into their products is advisable so that the impact of running is absorbed by the shoes. Otherwise try cushioning your shoes with orthopedic padded insoles.

Certain conditions like flat feet can also result in back pain over time. Also some people have a tendency to put more weight on one leg than the other; this discrepancy adds pressure on the spine resulting in lower back pain.

Bad posture while running can cause the spine muscles to tighten which leads to back pain. Some people run very rigidly, holding their shoulders very straight. The right technique should be to have a straight back with the shoulders leveled and relaxed.

Link: EZine Articles
http://ezinearticles.com/?Running-and-Lower-Back-Pain—What-You-Can-Do-About-it&id=4812401

Dr. Alan Weidner
http://www.massage-chair-relief.com/