Understand Back pain Back muscle sprain is very common 80% people at least get one episode of back spasm in their life time It is usually due to muscle weakness Repeated exertions or heavy lifting can cause back muscle spasm Initial stages it is due to muscle fatigue and is totally reversible with regular exercise However if we ignore the back pain then eventually patient develop disc prolapse with slipped disc and sciatica Disc Degeneration- Black disc on MRI. Looses normal Hydration. It looses the shock absorber quality. Sudden load on such disc causes disc rupture. Slipped Disc/ Disc Herniation-Usually acute episode. Sudden unusual exertion. Lifting heavy weight. Severe back pain. Nerve gets pinched. Associated leg pain / heaviness. Spinal Stenosis- Narrowing of spinal canal. Secondary to degeneration Leg pain > back pain. When you walk certain distance you get heaviness in legs