For many years the prevailing belief about low back pain was that it was caused by  "stuck" joints or restricted connective tissues. It spawned an industry of modalities to address the problem. Consequently, the "fix" was often manipulation, mobilization (a gentler form of manipulation) or stretching. Other practices such as "trigger point" release techniques (e.g. myofascial release, craniosacral therapy, ischemic pressure, strain/counterstrain, dry needling, etc.) also gained popularity - despite anecdotal evidence only. There is certainly evidence that manipulation and mobilization provide relief for new onset back pain. Unfortunately, an examination of the literature regarding whether different examiners reliably agree on which segment needs "fixed" has shown they don't. A study at Washington University in St. Louis found that unless positions of tissues varied by at least 1/2 inch, examiners did not agree reliably on findings. Spinal joints, imbedded deep under erector spinae muscles, are not believed to move more than a few millimeters. Other studies have shown that manipulative techniques are not specific to the intended segments in any reliable way! Nor can it be proven that a measureable change in  joint position is accomplished.
     This is not to say that patients don't find relief with these methods. Is it caused by a placebo effect? This is a possibility and not one to take lightly. Placebo pills in pain studies typically have a 20% success rate at decreasing symptoms and, as mentioned in Prime for Life, have been shown to increase endogenous opiates such as endorphins.  Another speculated reason for success with manipulation may be that it effects the nervous system - altering perception and motor control in subtle ways. We just don't know how or why it helps some people. Generally a good rule of thumb is that if a treatment doesn't last more than a few weeks, it is not affecting the cause of the problem.
      The Washington University in St. Louis "Movement System Impairments (MSI)" method of diagnosing and treating patients, though, has a different perspective. By having a patient perform systematic movements and watching for compensatory patterns and listening to patient reports of symptoms, clear and reliable patterns tend to emerge. Studies have shown that patients consistently report pain patterns, regardless of the examiner. As a practitioner who uses this system of diagnosing and treating patients, I am constantly struck by the almost universal pattern of excessive motion in the spine and consistent, accompanying complaints. The patient will add extra low back rotation or flexion or extension and complain of pain. When they are taught to restrict the extra motion, they report a decrease or elimination of pain. Upon questioning, they usually admit to some repetitive movement in their day-to-day life that repeats the offending motion. Sleeping on the belly with low back arching correlates to the examination and a realization that they wake up with pain. Or a twisting of the upper body to face the computer correlates to the report of pain with rotation or sidebending. Or doing early morning stretches of knee to chest and forward bends in yoga (when disc pressure is at its highest) is the link to pain with bending over. Changing movement patterns tends to permenently address the problem. I shows that the most common cause of musculoskeletal pain is faulty movement patterns, which stems from the brain - not the body. The problem is upstairs not downstairs in the spine.
     The passive "fixes" may decrease pain. In my experience usually only temporarily. If you keep bending your index finger back as far as you can, the knuckle becomes painful and swollen. Only by stopping the offending action can the knuckle stop hurting. It doesn't need stretched to the extreme opposite direction, or massaged, or manipulated - just treated respectfully. Extreme end-range stretches or manipulations are stressful to the body. Figuring out how you are offending your body's innate wisdom is the first step in staying in your prime. Avoiding pain or discomfort is the first step towards that goal.