Lumbago is a common term for non-specific low back pain. The most common cause of LBP is a sprain or strain and most will heal with time and rest. Either one involves muscles or tough, somewhat inelastic tissue called tendons (which connect muscles to bone) or ligaments (which connect bone to bone). The damage may be a mild over-stretching/twisting or a partial tearing. If this happens to muscle or tendon, it’s called a strain. If the injury is to ligaments, it is called a sprain. Complete pulling apart of tendons or ligaments requires a major injury, is much more disabling, and may require surgical repair. That’s not lumbago.
So-called lumbago can be persistent due to overwork or excess exercise or, conversely, due to too much prolonged sitting. It could be due to a disc protrusion, but usually isn’t. Symptoms are pain increase with movement, stiffness and limited movement due to muscle spasm. These symptoms usually improve 3-5 days after an injury and they should go away between 1-6 weeks.
In back sprain/strain it is only safe return to previous activities, such as athletics, when the pain has cleared. Pain-avoiding behavior that is caused by any remaining symptoms could place that person at risk for re-injury. Using pain relievers to resume whatever activity caused the back pain while still limited and in pain could mask a painful warning to stop and thus increase the risk of aggravating the existing injury or causing re-injury.