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Published on: 5/6/2025

Why Do I Feel a Lump in My Stomach When Doing Sit Ups?

During sit-ups, you may feel a lump in your stomach due to shifts in your abdominal tissues or fat, muscle strain or herniation, or even nerve entrapment such as ACNES, all of which can become more apparent during exercise.

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Explanation

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, it’s a good idea to have it evaluated by a healthcare provider to rule out any issues.

(References)

  • de Oliveira EP, Burini RC. The impact of physical exercise on the gastrointestinal tract. Curr Opin Clin Nutr Metab Care. 2009 Sep;12(5):533-8. doi: 10.1097/MCO.0b013e32832e6776. PMID: 19535976.

  • Bø K, Anglès-Acedo S, Batra A, Brækken IH, Chan YL, Jorge CH, Kruger J, Yadav M, Dumoulin C. Strenuous physical activity, exercise, and pelvic organ prolapse: a narrative scoping review. Int Urogynecol J. 2023 Jun;34(6):1153-1164. doi: 10.1007/s00192-023-05450-3. Epub 2023 Jan 24. PMID: 36692525; PMCID: PMC10238337.

  • Applegate WV. Abdominal Cutaneous Nerve Entrapment Syndrome (ACNES): A Commonly Overlooked Cause of Abdominal Pain. Perm J. 2002 Summer;6(3):20–7. PMCID: PMC6220638.

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