Why do I feel a lump in my stomach when doing sit ups?

When doing sit-ups, the contraction of your abdominal muscles and the increased intra-abdominal pressure can cause certain tissues to shift or become more noticeable. This can make underlying deposits of fat or benign lumps such as lipomas more perceptible. Additionally, muscle strain or small herniations—where a piece of tissue or fat pushes through a weak spot in the muscle—can feel like a lump.

Another possibility is that the repetitive movement and strain of sit-ups might irritate the abdominal cutaneous nerves, leading to a localized area of discomfort known as Abdominal Cutaneous Nerve Entrapment Syndrome (ACNES). In this condition, the trapped nerves can cause both pain and a sensation of a lump.

Exercise can also temporarily alter the position and function of your gastrointestinal tract, which might contribute to the sensation. While these causes are often benign, if the lump is painful, persists, or is accompanied by other symptoms, you can use Ubie's free AI symptom checker to help identify potential causes and determine whether you should seek medical evaluation.