When I ran in college, every other week the members of our varsity team were allowed to see a physical therapist who would stretch and massage our muscles after a hard workout with the goal of alleviating pain and speeding recovery.
This therapist was an eccentric man. It was like he was part physical therapist, part ancient medicine man. He would lightly manipulate the muscles of our legs, trying to find points of tension. Once he found a knot, he would invariably exclaim, "Are you smuggling diamonds in there?"
At that, he would go to work not only massaging the tense muscle, but also every muscle even tangentially related to that original tense muscle. He had an intimate knowledge of the entire muscular system of our bodies and seemed to be able to work miracles using that knowledge. At the end of each session, we would be quite sore. But when we woke up the next morning, each of us felt like a million bucks!
Massage is a very general term, referring to the rubbing and compressing of muscles with the goal of relieving muscle tension. For runners, massage can be a useful tool. It is true that there has not been a plethora of research on the effects of massage for runners.
In recent years, though, there have been several studies completed by The British Journal of Sports Medicine and The Journal of Athletic Training that found that while a post-workout massage did not have any effect on muscle function, it did significantly reduce delayed onset muscle soreness (DOMS). Essentially, this means that when an individual received a massage after working out, in the days following the workout that individual was less sore than others who did not receive a massage.
But when should a runner seek out a massage? The best time to get a massage is after a hard workout, when muscles are tightest. It is important that you not receive a massage shortly before a hard effort, because a massage can leave your muscles feeling sore in the hours immediately following the treatment. If you have access to a therapist, it is would be great to get a massage on a weekly basis, although that would be an expensive habit. Once every two to four weeks is a common frequency to receive massage therapy.
One final important note is that not all masseurs are specifically trained to work with runners. If you are interested in receiving a massage, it is recommended that you seek out a physical therapist that specializes in therapy for distance runners. You will get significantly more out of your massage if the person delivering the treatment knows the specific physiology of runners.