Exercise is a powerful tool -- but as much as it does a body good, it can also harm. Many people don't realize the exercises they do in pursuit of the perfect six-pack actually widen the waist and can ultimately lead to a pooch. Crunches, sit-ups, and even many pilates moves cause the abdominal wall to bulge forward, straining the connective tissue that runs up and down the center of your rectus abdominis (the six-pack muscles). Yes, those exercises strengthen your abs, but they do so at the expense of your connective tissue. Repeated forceful stress on that tissue will physically separate the muscles, a medical condition known asdiastasis recti. This tends to obliterate the waistline, leaving fit women with what we call an "athletic build" (no curves), and men with a paunch. Sit-ups and crunches are not the only culprit... so is pregnancy. The majority of pregnancies result in diastasis recti, wreaking havoc on a formerly firm, flat stomachs.
Good news! Whether the separation was exercise induced or pregnancy related, there is a non-invasive solution. Deep engagement of the transverse abdominis, your natural corset, effectively draws the two halves of the rectus abdominis back together and restores the integrity of the connective tissue. The same exercises that deliver firm, flat abs to my postnatal clients have also worked wonders to help my male clients -- including athletes and body builders -- to repair separated abs for tighter six-packs and narrower waists.
So what can you do to achieve the abs of your dreams? Ditch sit-ups, forget crunches and replace them with these five exercises:
Plank with core compressions 
Take this classic exercise up a notch by adding core compressions to correctly recruit your deepest abdominal muscles. Assume a plank position, either on the floor or on an incline (as shown) and pulse your abs tight to tighter, flat to flatter, exhaling with each squeeze. Keep your spine perfectly straight throughout. Perform three sets for 60 to 90 seconds each.
Waist anchor
Featured in this video clip, the waist anchor recruits the full length of your rectus abdominis, emphasizing the upper abs while avoiding the neck strain common with crunches. Perform three sets for 90 seconds each.
Side plank with core compressions
Assume a side plank on your forearm, with the elbow directly below the shoulder. Legs may be bent (as shown) or straight for greater challenge. Keep your spine perfectly still and pulse your abdominal muscles tight to tighter, flat to flatter as you exhale. In addition to activating your transverse abdominis, you are also toning and defining your obliques. Perform two planks on each side, 60-90 seconds each.
Waist cincher
The waist cincher (presented in this video clip) strengthens and firms the full length of your rectus abdominis, as opposed to bulging and weakening the center as happens in a classic crunch.
Waist cincher with twist 
As I thoroughly explain in this blog post (click here to read Bye, Bye Bicycle Crunches), bicycle crunches hit your abs with a double whammy: they bulge the abdominal wall forward, causing the muscles to separate, but they also splay them further apart directly at the belly button because of how this movement recruits the obliques. To safely tone your obliques without the collateral damage of a bicycle crunch, do waist cincher with twist.
Begin by lying on your back with your knees bent. Then drop both knees to one side while keeping your shoulders square to the ceiling. This positions you in a spinal twist. Place one hand on your abs, directly over the belly button. Tuck the other hand under your head to support the neck. Prepare by taking a small breath. Then exhale and draw your belly button flat to the spine as you nod your head "yes." Be sure to draw the chin gently toward the chest as you nod -- it's a tiny movement. The shoulders stay in contact with the floor throughout the entire range of motion. Inhale as you return your head to the starting position and soften the abs. Perform two sets on each side for 90 seconds each.
By changing how you train, you can achieve measurable results in as little as six weeks. Swap out crunches for the above routine, and you will both see and feel the difference. Full video instruction in the above exercises is available in the 10 Minutes Flat system. For more information, visit my website.
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