That Daily Set of Crunches Might Be Working Against Your Belly
If your tummy bulges or peaks when you sit up, your hardest abs work could be quietly making the gap worse.
If you have been grinding through crunches and sit-ups hoping to flatten your mum tummy, only to feel like nothing is shifting, you are not doing it wrong out of laziness. The question of whether crunches make diastasis recti worse comes up constantly, and the honest answer is that for many new mums in early recovery, yes, traditional crunches can stall progress and even make the belly pooch look more pronounced. The good news is that understanding why means you can swap to movements that actually rebuild your core from the inside out.
Quick answer
Crunches and sit-ups can make diastasis recti and your postpartum belly pooch worse because they spike pressure inside the abdomen and pull the separated tummy muscles outward, often causing the midline to bulge or dome. In early recovery, before the deep core and connective tissue have re-strengthened, repeated loaded crunches can keep that gap stretched. Gentle deep-core and breathing-led exercises are usually a safer first step.
What diastasis recti actually is (and why crunches matter)
During pregnancy your growing uterus stretches the two bands of your six-pack muscles (the rectus abdominis) apart, thinning the connective tissue down the middle called the linea alba. This widening is diastasis recti, sometimes called abdominal separation or ab separation. It is extremely common and a normal part of pregnancy. For many women the gap narrows on its own in the early weeks and months, but for others it lingers and shows up as a lower belly bulge that will not go down, or a ridge that pops up when you get out of bed.
Here is the key point. The linea alba is connective tissue, not muscle. You cannot strengthen connective tissue the way you train a bicep. What you can do is rebuild the deep core that supports it and learn to manage the pressure that pushes against it. Crunches do the opposite. They load the very tissue that is trying to knit back together while it is at its most vulnerable, which is exactly why so many mums searching "are crunches bad for diastasis recti" are onto something real.
Why crunches and sit-ups make the belly bulge worse
When you do a crunch, you flex your spine and contract the outer abdominal muscles hard. In a body without separation, this is fine. But when there is a gap and weak connective tissue in the middle, that contraction increases intra-abdominal pressure and pushes your organs forward against the thinned linea alba. With nothing strong to hold it back, the midline pooches outward. This is why crunches can make belly bulge worse rather than flatter, and why a daily crunch habit can keep your tummy looking domed and rounded.
There is a second issue. Loaded flexion like crunches and sit ups trains the outer "mirror" muscles while the deep stabilising layer underneath stays switched off. You end up gripping and bracing through movements that should be supported from within. Over time that can reinforce the very pattern that makes your mum tum stick out. If you have ever wondered "should I do sit ups after pregnancy" and felt your belly cone up when you tried, that cone is your answer for now.
Rebuild your core the right way
Stop guessing which moves help and which set you back with a clear, gentle plan made for ab separation.
Explore the Diastasis Recti Fix, and new mums get 20% off with code GLOW20.
The doming sign every new mum should learn to spot
The single most useful skill you can build is recognising doming, sometimes called coning. This is the tell-tale sign that an exercise is too much for your current core. Doming when doing sit ups postpartum looks like a ridge, peak, or tent of tissue pushing up along your midline when you exert yourself, especially as you lift your head and shoulders off the floor.
To check yourself, lie on your back with knees bent, place a hand lightly over your belly button, and slowly lift your head. If you feel a soft squishy gap, or see the middle bulge up into a ridge, that movement is loading your linea alba more than it can hold right now. Pelvic health physiotherapy guidance recommends screening for this doming before progressing any exercise. If a movement makes you dome, it goes on your "not yet" list, no matter how much your old routine relied on it.
Exercises to avoid with diastasis recti right now
It helps to know what not to do with abdominal separation in the early stages so you can stop spinning your wheels. None of these are banned forever. They are simply ones to park until your deep core can handle the load without doming.
| Move to pause | Why it can set you back | What it does to the midline |
|---|---|---|
| Crunches and sit-ups | Loaded spinal flexion spikes pressure on the gap | Pushes the belly outward, encourages doming |
| Full front planks (early on) | Hard to hold without bracing through a weak core | Can sag or dome if you cannot keep tension |
| Bicycle crunches and V-sits | Combine flexion and rotation under load | High pressure, very common doming trigger |
| Heavy lifting with breath-holding | Bearing down spikes intra-abdominal pressure | Strains the linea alba you are trying to heal |
People often ask about planks and diastasis recti, safe or not. The honest answer is that planks live in a grey zone. A full plank early in recovery is usually too much, but a modified incline plank against a wall or kitchen counter, where you can keep your core gently drawn in without doming, can be a useful progression once your foundation is back. The rule is always the same. Watch your midline. No doming, no bearing down. For a fuller breakdown of which moves help and which hold you back, this guide on which workouts help diastasis recti and which make it worse walks through the swaps in detail.
Safe alternatives to crunches after baby
Rebuilding your core is not about doing nothing. It is about doing the right things in the right order. The foundation is learning to engage the deep core, your transverse abdominis and pelvic floor, which act like an internal corset that supports the midline. These are the safe alternatives to crunches after baby that genuinely move the needle.
Foundation moves to master first: deep core breathing, gentle pelvic tilts, and heel slides
Doming or bulging you should feel during a well-chosen exercise
Minutes a day is enough to start retraining your deep core consistently
Start with diaphragmatic breathing. Breathe in to let your belly and ribs expand, then exhale slowly and feel your lower tummy draw gently inward and up, as if zipping up a snug pair of jeans. That gentle draw-in is your transverse abdominis switching on. From there you can layer in pelvic tilts, heel slides, and supported leg lifts, always keeping that gentle tension and always checking for doming. These small movements look unimpressive next to a hundred crunches, but they are what actually close the gap and flatten the pooch over time.
One more thing worth knowing. Sometimes that stubborn lower belly is not only about separation. If you are not sure whether your bulge is the gap, softness, or something else, it is worth reading whether your pooch is diastasis recti or just belly fat so you can target the right thing rather than punishing your abs with crunches that were never going to work.
A gentle plan that skips the moves that backfire
Trade crunches for a step-by-step deep-core routine designed around ab separation, not against it.
Explore the Diastasis Recti Fix, and new mums get 20% off with code GLOW20.
When to check in with a professional
Most mums can begin gentle deep-core work safely, but a few signs are worth a conversation with your GP, midwife, or a women's health physiotherapist. See someone if you still have a noticeable gap of more than about two finger-widths several months postpartum, if you feel a soft bulge or have any sense of something pushing through the midline, if you have ongoing back pain or pelvic floor symptoms like leaking, or if you simply want hands-on guidance. A physio can assess your gap, check your doming, and tailor a progression to you. There is no prize for pushing through, and skipping crunches is not giving up. It is the smarter route to a stronger, flatter middle.
Frequently asked questions
Are crunches bad for diastasis recti?
For many women in early recovery, yes. Crunches load the separated midline and increase pressure inside the abdomen, which can push the belly outward and cause doming. They are best paused until your deep core is strong enough to keep the midline flat during effort.
Why do crunches make my belly pooch look worse?
Crunches contract the outer abs hard while the connective tissue down the middle is still weak. That spikes pressure against the thinned linea alba and pushes your tummy forward, so the pooch can look more rounded rather than flatter.
What is doming and why does it matter?
Doming, or coning, is a ridge or peak of tissue that pushes up along your midline when you exert yourself, such as lifting your head during a sit-up. It is a sign the exercise is loading your healing tissue too much, so you should swap to a gentler movement.
Should I do sit-ups after pregnancy?
Not as your starting point. Sit-ups are loaded spinal flexion that commonly trigger doming when there is a gap. Begin with deep-core breathing and gentle stability work, and only return to flexion-based moves once you can do them without bulging or doming.
Are planks safe with diastasis recti?
It depends on the version and your stage of recovery. Full front planks are usually too much early on, but modified incline planks against a wall or counter can work once your deep core is strong enough to hold tension without doming. Always watch your midline.
What can I do instead of crunches?
Focus on deep-core breathing, gentle pelvic tilts, heel slides and supported leg movements that engage your transverse abdominis and pelvic floor. These rebuild the internal support that flattens the belly, without straining the separation.
Sources: Cleveland Clinic (diastasis recti, avoiding doming and strain on the linea alba); ACOG (postpartum exercise guidance and graded return to activity); POGP, Pelvic, Obstetric and Gynaecological Physiotherapy (screening for doming before progressing exercises).
This article is general education and not medical advice. Postpartum recovery is individual and results vary. Always check with your GP, midwife, or a women's health physiotherapist before starting new exercise, especially after a c-section or if something does not feel right.