connective tissue - tissue of mesodermal origin consisting of e.g. collagen fibroblasts and fatty cells; supports organs and fills spaces between them and forms tendons and ligaments

collagen - a fibrous scleroprotein in bone and cartilage and tendon and other connective tissue; yields gelatin on boiling

muscle system, muscular structure, musculature - the muscular system of an organism

hamstring, hamstring tendon - one of the tendons at the back of the knee

Achilles tendon, tendon of Achilles - a large tendon that runs from the heel to the calf

strength - the property of being physically or mentally strong; "fatigue sapped his strength"