Are you spending time each day doing crunches or sit ups to achieve a flat stomach. A 6 pack perhaps? Quit wasting your time!!
While a crunch or sit up can strengthen your top layer (the rectus abdominus) it doesn’t strengthen the rest of the abdominals and core. It also activates the psoas major (hip flexor) which places stress on the lumbar spine. Studies show that 80% of adults experience back pain throughout their life. If crunches exacerbate this issues and aren’t that effective why are you still doing them?? Some people believe that the top layer is all that matters but it goes much deeper than that.
The core works together to stabilize the body and isolating one muscle and ignoring the rest of the group will not get you the results you want and you are likely to get injured.
Some of the best exercises for the core are push ups, planks, squats on an unstable surface, single arm chest presses and single arm chest flys, mountain climbers and renegade rows. You want to create an unstable environment so the core has to engage.
They key is to train the whole body. The core is supposed to engage before any other muscle group activates. Practice tightening your core before you perform an exercise like a squat or lunge or shoulder press.
Try not to perform a crunch or sit up for 30 days. Use other exercises (especially stabilization exercises like a plank or side plank) instead. We are in trunk flexion too much already by sitting at desks, slouching on the couch, etc. No need to do so in your workout.
Also, don’t forget that nutrition plays a big role in getting that stomach flat. You could have a very strong core but to see its definition, you may need to lose a bit of fat that is on top of it. Remember, fat doesn’t turn into muscle. They are different and you must eat healthy in addition to exercise.