Do massage chairs help alleviate lower back pain?

As answered prior. As stated if the massage chair helps your symptoms use it. Otherwise enroll in a formal physical therapy program . If your pain persists see an orthopaedic spine specialist .
If pain is muscular. They will if pain is muscular in nature but will be short lived after getting up from chair. Unless you just strained a muscle, most back pains are from other causes presenting with muscular symptoms so you just are treating a symptomatic area but not the actual problem. The good news is that most back problems get better over time. If symptoms don't improve or worsen, see your doctor.
Possibly. Muscle strains are the primary cause of back pain. The massage effect may help from a machine or from a human. If it helps go for it!