Lower back pain is such a common complaint and those that suffer with it yet want to strengthen their backs in the gym, may train in ways that put strain on other areas of the body in an effort to protect the area and avoid pain. This compensation can cause more trouble. But before you try to remember how you pulled a muscle or strained yourself lifting something heavy, you may want to try a simple test that could solve the problem.
This technique may work if the pain is non specific (where the cause is not immediately apparent or related to causes such as diseases or accidents for example).
A tip I was given by a Kinesiologist was to drink a pint of water and see if the pain eased. Life can be hectic and often people rely on teas and coffees to quench their thirst and the body can become accustomed to fewer liquids.
The reason this tip make work for you is that the psoas muscle is usually involved in one way or another with lower back pain. This is a strong muscle that runs along the lower mid spine and its function is to primarily to flex the hip and the spinal column. The psoas muscle is also related to kidney function in applied kinesiology and if dehydration is present, this can throw the psoas off balance and pain can be felt.
Initially you will probably feel like you need to urinate immediately, but if you keep drinking the minimum 8 glasses of pure water per day, you will soon become accustomed to it and feel a lot better in many other ways too, such as feeling more alert and energetic.
So if you drink more tea and coffee than plain water, yet suffer with lower back pain, try drinking a pint of water and see how you feel.