The latissimus dorsi is the broadest muscle of the back. It extends from the top of the hip to the lower six thoracic vertebrae in the mid-back and up to the top of the humerus -- the bone in the upper arm that forms the ball of the ball-and-socket shoulder joint -- at the front of the shoulder.
In baseball, most lat strains are suffered by pitchers and occur at the top end of the muscle near the humerus, which is why they are often difficult to diagnose. They are often initially treated as biceps tendinitis or a rotator cuff issue, because physicians don't always recognize that lat strains can create anterior shoulder soreness due to the attachment at the front of the shoulder.
Like all muscle strains, the lat strain is broken down into three grades. Grade 1 is a mild strain, Grade 2 is a moderate strain and Grade 3 is a severe strain in which the muscle ruptures.
Typical recovery time
Recovery time varies depending on the strain, with Grade 1 strains typically requiring 2-3 weeks and Grade 2 strains usually taking at least a month. Grade 3 strains often require surgery, however, and can come with considerably longer recovery periods. In 2010, Jake Peavy became the first Major League pitcher to have a lat surgically repaired when his tore completely off the humerus, causing him to miss more than 10 months.
Mets ace Noah Syndergaard suffered a lat strain in 2017. He began his rehab assignment roughly five months after being placed on the disabled list. Other pitchers to deal with the injury include Jake Peavy, Roy Halladay, Kerry Wood, Stephen Strasburg, Trevor Rosenthal and Huston Street. In 2010, Peavy became the first big league pitcher to have a lat surgically repaired when his tore completely off the humerus. Peavy missed a year of baseball with that Grade 3 injury before returning to become an All-Star in 2012.