Hundley pulled up lame as he reached third base, and left the game soon after. There are 11 intercostal muscles on each side of the rib cage. They connect one rib to another and work to spread the ribs apart and bring them back together again, effectively expanding and contracting the chest to aid in breathing. A stretching or rotating movement can sometimes tear this muscle, which is what appears to have happened to Hundley. Initially, there may be constant or severe pain, but after a few days, the pain occurs only on stretching, coughing, or breathing deeply.
Most injuries heal within a few weeks.
This type of injury is easily diagnosed using clinical examination. X-rays are usually done to ensure that there is no fracture of the ribs, and an MRI can be used to determine that there is no cartilage damage and also to positively ID the sprain and its exact severity. Since a strain is a mild muscular injury, it is treated with rest, ice, anti-inflammatories, and gentle stretching exercises. Most importantly, the athlete must try to limit the movement of the torso, because each bend or stretch can further tear or limit the healing of the ribcage muscles. The best stretches for this muscle group are side-bending exercises and side bending with rotation.