1 Collagen is most commonly found within the body in the skin, bones and connective tissues. 2  The word collagen is derived from the Greek kolla, meaning glue. 3  Collagen gives the skin its strength and structure, and also plays a role in the replacement of dead skin cells. Collagen is most commonly found within the body in the skin, bones and connective tissues. 2  The word collagen is derived from the Greek kolla, meaning glue. 3  Collagen gives the skin its strength and structure, and also plays a role in the replacement of dead skin cells.
Healing time depends on the severity of the strain. Mild muscle strains usually heal within two weeks. Moderate muscle strains may take six to eight weeks to heal. Prevention of Recurring Back Strain. Many people who experience recurring back pain have weak core muscles - the muscles that support the back.
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 the torn muscle is repaired surgically.