Low back strain

 From WebMD Low Back Strain Causes, Treatments, Exercises, Prevention (webmd.com)

So what is low back strain? A series of muscles and ligaments in your back hold the bones of your spinal column in place. You can strain these muscles by stretching them too far, causing tiny tears in the tissue. The muscles are then weakened, so they may not be able to hold the bones of your spinal column in place correctly. The spine becomes less stable, causing low back pain.

And because nerves stretch out from the spinal cord throughout the entire body, low back strain can cause pain in areas other than your back.

Low back strain can be caused by:

• Extreme physical exertion.
• Falling.
• Bending or crouching repeatedly.
• Lifting heavy objects if you are not in shape.

It can also be caused by emotional stress, improper posture, being overweight, out of shape, or sitting in the same position for long periods of time. Even a severe cough can result in low back strain.