That deep, achy feeling across your midsection, as though you spent the morning doing crunches you have no memory of, usually traces back to your abdominal muscles or the nerves running through them. The causes range from the perfectly mundane (a hard coughing spell, an awkward sleeping position) to the less obvious (a trapped nerve, a spinal problem sending pain signals to the wrong neighborhood). Most of the time the sensation is harmless and temporary, but the sheer number of things that can produce it means the answer is rarely one-size-fits-all.
Your Muscles May Have Worked Harder Than You Realized
The most straightforward explanation is that your abdominal muscles genuinely did exert themselves, just not through deliberate exercise. Any activity that repeatedly contracts the muscles of the abdominal wall can leave them feeling sore the next day. A violent bout of coughing is a common culprit: each cough forces the diaphragm and abdominal muscles to contract sharply, and a prolonged illness like bronchitis or a bad cold can rack up hundreds of forceful contractions in a single day. The internal oblique, one of the deeper layers of your abdominal wall, is especially vulnerable because it contracts hard during every cough. In extreme cases, forceful coughing can even rupture small blood vessels inside the muscle, producing a hematoma that feels like a sudden, intense soreness far beyond what you would expect from a cough alone.1PubMed Central. Severe Abdominal Pain due to Cough‐Induced Internal Oblique Muscle Hematoma: A Case Report
Vomiting works the same way. If you have been sick with food poisoning or a stomach bug, the repeated heaving puts your rectus abdominis through what amounts to an involuntary ab workout. Intense or prolonged laughter, sneezing fits, and even straining during constipation all recruit the same muscles. People are often caught off guard because they associate muscle soreness with the gym, not with being sick on the couch.
Delayed-Onset Muscle Soreness Without the Obvious Trigger
Delayed-onset muscle soreness, the stiff, tender feeling that peaks a day or two after unfamiliar exertion, does not require a traditional workout. Yard work that involves twisting and lifting, carrying a heavy bag through an airport, playing with kids on a trampoline, or even a long day of painting a ceiling can load the abdominal muscles in ways they are not accustomed to. The soreness shows up roughly 24 to 48 hours later, which makes the connection easy to miss: by the time your stomach hurts, you have already forgotten that you spent Saturday afternoon shoveling mulch.
A case report from a 44-year-old woman illustrates how unexpectedly this can play out. After a single intense abdominal exercise session, she developed pain not in the superficial “six-pack” muscles but deep in the psoas major, a hip flexor buried behind the abdominal organs. Imaging showed significant swelling in the muscle. She recovered fully with rest within two weeks, but the episode looked serious enough that it initially raised concern about something more dangerous.2Acta Medica. Delayed-Onset Muscle Soreness of the Psoas Major Muscle Following Abdominal Training: Case Report – Section: abstract
The takeaway is that even one unusual bout of physical effort can leave deep abdominal muscles feeling worked over for days, and the soreness can show up in areas that do not feel like typical “ab” muscles at all.
Nerve Entrapment in the Abdominal Wall
If the sore, crampy sensation keeps returning in a very specific spot, especially along the outer edge of the rectus muscle, the problem may not be the muscle at all. Anterior cutaneous nerve entrapment syndrome, or ACNES, happens when one of the small intercostal nerves running through the abdominal wall becomes irritated or pinched where it passes through a narrow opening in the muscle fascia. The resulting pain can feel remarkably like a strained or overworked muscle.3PubMed. Anterior cutaneous nerve entrapment syndrome
ACNES tends to be localized to one small area, often no bigger than a fingertip. Pressing on that spot reproduces the pain, and the pain frequently gets worse with movements that tense the abdominal wall, like rolling over in bed or laughing. People with ACNES often go through extensive testing for gastrointestinal problems before the real cause is identified, partly because the idea of a “pinched nerve in the stomach” is not intuitive for most patients or even for some clinicians.
A useful distinguishing clue is consistency. Muscle soreness from overuse generally improves day by day and resolves within a week. Nerve entrapment tends to persist or recur in the same location for weeks or months. If you can put a single finger on the sorest spot and it stays in exactly the same place visit after visit, that pattern points more toward a nerve issue than a muscle one.
How to Tell Abdominal Wall Pain from Something Deeper
One of the trickiest things about abdominal soreness is figuring out whether the problem lives in the wall itself (muscles, nerves, fascia) or inside the abdomen (stomach, intestines, gallbladder, and so on). The distinction matters because the workup and treatment diverge sharply depending on the answer.
There is a surprisingly simple bedside test that helps sort this out. Carnett’s test involves lying on your back and having someone press on the sore area. You then lift your head or legs to tense your abdominal muscles while the pressure continues. If the pain stays the same or gets worse when the muscles are tensed, the problem is in the abdominal wall. If the pain decreases, the tensed muscles are shielding an internal organ, and the source is deeper.4PubMed. Diagnostic usefulness of Carnett’s test in psychogenic abdominal pain Multiple clinical reviews have confirmed its usefulness for chronic abdominal wall pain specifically, though it is less reliable in acute or emergency situations.5PubMed. The Diagnostic Value of Carnett’s Test with Chronic Abdominal Pain: A Narrative Review
The reason this matters is that abdominal wall pain is frequently misdiagnosed. Patients are sometimes told they have irritable bowel syndrome, functional pain, or even a psychological condition when the actual problem is a muscle strain, a nerve entrapment, or a fascial defect sitting right under the skin. When a clinician suspects abdominal wall pain, a local anesthetic injection into the tender spot can both confirm the diagnosis and provide relief. In one study, injection of lidocaine combined with a steroid relieved pain for at least four weeks in the vast majority of patients.6PubMed Central. Chronic Abdominal Wall Pain That kind of response essentially rules out an internal organ as the source.
Diastasis Recti and Changes to the Abdominal Wall
For people who have been through pregnancy, significant weight changes, or abdominal surgery, the structure of the abdominal wall itself can shift in ways that produce a chronic feeling of strain. Diastasis recti, a separation of the left and right halves of the rectus abdominis along the midline, is one of the more common examples. The connective tissue between the muscles stretches and thins, leaving less structural support across the front of the abdomen.
The sensation this creates often feels like low-grade soreness or fatigue in the abdominal muscles, as though they have been working harder than normal just to hold things together, because in a sense they have. Women with diastasis recti report higher levels of abdominal pain, often experienced as discomfort or bloating, along with reduced satisfaction with how their body feels and functions.7Journal of Gynecology Obstetrics and Human Reproduction. Self-reported symptoms in women with diastasis rectus abdominis: A systematic review – Section: Conclusions The pain tends to worsen with activities that demand abdominal bracing, like lifting a toddler or getting out of bed, and eases at rest.
Diastasis recti is not exclusive to postpartum women; it can occur in men and in people who have gained and lost substantial abdominal weight. If the “I did sit-ups” feeling is centered along the midline and you can feel a soft gap between the muscles when you crunch slightly, it is worth having a clinician evaluate for separation.
When the Problem Is Actually in Your Back
This one surprises almost everyone. The nerves that supply sensation to the skin and muscles of the abdomen originate in the thoracic spine, the section of the backbone behind the ribcage. When one of those spinal segments becomes stiff, irritated, or compressed, the nerve signal can travel forward along the rib and register as abdominal pain. The result is a sore, aching stomach that has nothing to do with the stomach at all.
This phenomenon has been recognized in medical literature for over 80 years, yet clinicians still frequently miss it. One published case report documented a patient whose abdominal pain was so convincing that it mimicked appendicitis, leading to diagnostic confusion before thoracic spine dysfunction was finally identified as the cause.8PubMed Central. Pseudoappendicitis: abdominal pain arising from thoracic spine dysfunction-a forgotten entity and a reminder of an important clinical lesson The pain can be sharp or dull, unilateral or spread across a band around the torso, and it often worsens with certain body positions or deep breaths.
If you notice that the soreness in your abdomen tends to flare when you twist your torso, sit for long periods, or have recently tweaked your back, the spine is worth investigating. Physical therapy targeting the thoracic spine resolves the abdominal symptoms in many of these cases, which feels almost absurdly satisfying when you have been worrying about your gut the whole time.
Muscle Cramps, Electrolytes, and the Middle-of-the-Night Spasm
Some people describe the feeling less as soreness and more as a sudden, gripping cramp across the abdomen, almost like a charley horse in the midsection. Abdominal muscle cramps can strike during or after exertion, but they also wake people up at night for no clear reason.
The popular explanation is dehydration and low electrolytes, and there is partial truth to it. Staying hydrated and maintaining electrolyte balance does seem to delay the onset of exercise-related cramps. In one controlled study, participants who drank a carbohydrate-electrolyte solution during exercise lasted more than twice as long before cramping compared to those who were dehydrated. But roughly seven out of ten participants in that same study still cramped even when fully hydrated and supplemented, which tells us that fluid and minerals are only part of the picture.9PubMed Central. Influence of Hydration and Electrolyte Supplementation on Incidence and Time to Onset of Exercise-Associated Muscle Cramps
Muscle fatigue itself, especially in muscles that are deconditioned or working in a shortened position, appears to be a major contributor. If your abs cramp at night, it may be that you spent the day using them in an unfamiliar way, and the fatigued muscle fires involuntarily while you sleep. Gentle stretching, adequate hydration, and progressive strengthening tend to reduce the frequency over time, but the honest answer is that exercise-associated cramping is still not fully understood, and the advice to “eat a banana” is an oversimplification.
Small Hernias You Cannot See or Feel
Tiny hernias in the abdominal wall, particularly epigastric hernias along the midline above the navel, can produce a vague aching that closely mimics muscle soreness. These hernias involve small bits of fat (and occasionally peritoneal lining) poking through a gap in the linea alba, the fibrous strip running down the center of the abdomen. They are often too small to see or even palpate, which is why they tend to be discovered incidentally on imaging or missed entirely.
The pain from a small epigastric hernia usually worsens when you strain, cough, or bear down, and it may come and go depending on body position. Because the hernia is tiny and the swelling is not visible, the sensation reads as “my muscles are sore for no reason.” If the aching is persistently midline and worse with abdominal effort, ultrasound or CT can spot what the physical exam cannot.
Practical Steps When the Soreness Is Unexplained
Before assuming the worst, run through the obvious possibilities. Have you been coughing, vomiting, sneezing, or laughing more than usual in the last few days? Did you do any physical activity that involved bending, twisting, lifting, or bracing your core? Sleep in a strange position? Start a new medication that causes constipation? Any of these can leave the abdominal muscles feeling as though you put them through a workout.
If the soreness is diffuse, comes on gradually, and improves over a few days, you are almost certainly dealing with muscular strain or delayed-onset soreness. Rest, gentle movement, and over-the-counter pain relief are usually sufficient.
Patterns that warrant a medical visit include:
- Persistent focal tenderness: pain that stays in one very specific spot for more than a couple of weeks, which may indicate nerve entrapment or a small hernia.
- Pain that worsens when you tense your abs: this suggests the abdominal wall itself is the source and a clinician can perform Carnett’s test to confirm.10PubMed. Abdominal Wall Pain: Clinical Evaluation, Differential Diagnosis, and Treatment
- Associated back stiffness or positional changes: may point toward a thoracic spine origin worth investigating with physical therapy.
- Fever, vomiting, blood in stool, or unintentional weight loss: these are signals that something beyond the abdominal wall needs evaluation and should not be chalked up to muscle soreness.
Why This Gets Misdiagnosed So Often
Abdominal wall pain occupies an awkward blind spot in medicine. When a patient reports stomach pain, the reflex is to think about the organs inside the abdomen. Blood tests, imaging, and endoscopy are ordered to look at the liver, gallbladder, appendix, intestines, and stomach lining. When those come back normal, the patient is sometimes told the pain is “functional” or stress-related, and everyone moves on unsatisfied.
The problem is that abdominal wall conditions (muscle strain, nerve entrapment, fascial defects, small hernias) do not show up on standard GI workups. They require someone to think about the wall as a potential source, press on it in the right way, and test whether the pain responds to the wall being tensed. Chronic abdominal wall pain has been described in medical literature as “often mischaracterized as a functional complaint,” and the characteristic finding is pain that is strictly localized and reproducible on examination.6PubMed Central. Chronic Abdominal Wall Pain When recognized, it responds well to local treatment. When missed, patients endure years of unnecessary tests.
If you have had a thorough GI workup that found nothing and your stomach still feels like you did sit-ups, it is entirely reasonable to ask your doctor specifically about abdominal wall pain and whether Carnett’s test or a trigger-point injection might be appropriate. The answer may have been sitting right under the surface the whole time.