A blocky or square waist is not the shapely, contoured look you're after. The way to avoid square obliques isn't to train your abs more, but to train them less. Too many weighted ab moves, especially side bends and crunches, can overdevelop your abs.
Your abs, including your obliques, activate during many exercises — whether they're directly targeted or not. To avoid getting square obliques, be prudent with how much oblique and ab training you add in addition to regular strength workouts.
What are the Obliques?
The obliques are the ab muscles at the sides of the waist. The external obliques are broad, flat and visible. The internal obliques lie beneath the external obliques. Both sets of muscles are responsible for side bending and twisting.
When they're overdeveloped, the obliques can look thick, or square. If you desire a defined, tapered midsection — for competition or just plain old good looks — thick obliques are your enemy. This is especially true for female figure competitors and body builders.
Moves that Encourage Square Obliques
You hammer your core with workouts in an attempt to slim it, but that's not how muscles work. Lots of abdominal exercises actually encourage muscle fibers to grow thicker and stronger, expanding your obliques and making them take on a square appearance.
Multiple workouts per week that include weighted twists, body saws, side bends and lying leg raises, for example, encourage stronger — and bigger, squarer — muscles at the sides of your waist. You're especially at risk if you include these moves three or more times per week, add load and do excessive repetitions, such as 20 or more.
Take Action to Be Strong, Not Square
Functional training for your obliques is important. A few sets of 10 to 12 oblique strengthening moves, such as bicycle crunches and side planks, keeps your torso strong for side bending and rotation, but doesn't build excessive muscle. Aim to do these moves just twice per week and avoid working to failure.
Don't forget the importance of clean eating — focusing on whole, unprocessed foods for the most part — and sticking to only modest servings of carbohydrates, even healthy ones such as starchy vegetables and whole grains. This type of diet encourages you to lose excess fat, especially if you keep your calorie intake under control. Excess fat can contribute to a thick middle.
Total-body strength training will encourage a balanced physique and also activate your abs, so they stay strong, but not overdevelop. Squats, deadlifts, chest presses, dips, curls, lunges and shoulder presses are standard moves to include in your regimen.
Only So Much Is in Your Control
You can't narrow the size of your hips; that's determined by your bone structure. So, if you're looking at your core and the squareness is in your hips, it's your genetics, not workouts. You can increase the appearance of taper by doing more shoulder and upper back work to broaden your upper body.
You can also control the width of your waist from front to back by training with the stomach vacuum exercise. This move is done by hugging your belly button in and under your rib cage to create a hollowed out appearance to your abs. Hold it 20 seconds or longer to train the deep abdominal muscle known as the transverse abdominis, which is also critical in supporting your spine and preventing back pain.