The oblique muscles lie alongside the rectus abdominis muscles -- the ones that make up the "six pack" -- and are responsible for core control and rotation. The internal oblique sits under the external oblique and is the most commonly injured abdominal or core muscle in baseball because it is the most activated core muscle during hitting and throwing.
Like all muscle strains, the oblique 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
While some mild oblique strains can be resolved in just a few days, severe strains can require surgery with a recovery time of 3-4 months. In 2017, former Dodgers athletic trainer Stan Conte of Conte Injury Analytics teamed with the Hospital for Special Surgery in New York City and Major League Baseball to further examine the impact of oblique strains on injured MLB players. Using MLB's Health and Injury Tracking System (HITS), the study ultimately revealed that hitters typically take 27 days to recover from a Grade 1 strain, while pitchers typically take as many as 35 days.