Your doctor will ask what type of activity triggered your muscle pain and whether there was a pop in the muscle at the time of injury. The doctor will ask about your symptoms, especially any decrease in muscle strength or difficulty moving.
Your doctor will want to know whether you've had recent fever, weight loss, leg numbness, urinary or bladder problems, or other symptoms that may point to a more severe medical problem.
After noting your symptoms and past medical history, your doctor will examine you, checking for muscle tenderness, spasm, weakness and decreased muscle movement. If this exam points to a mild or moderate muscle strain, you may not need additional testing. However, if the diagnosis is in doubt, X-rays or magnetic resonance imaging (MRI) may be helpful.
If you have back pain, your doctor may order additional tests to check for a urinary tract infection or a problem involving the vertebrae (backbones), vertebral disks, spinal canal or spinal cord.
How long a sprain lasts depends on the location and severity of the injury. Symptoms of a mild back strain usually improve within one to two weeks and are gone within four to six weeks. In the legs, mild or moderate strains may take up to 8 to 10 weeks or more to heal. Symptoms of a severe (Grade III) strain may persist until a surgeon repairs the torn muscle.