It's hard to find a person who wouldn't like to have a washboard-flat stomach with rippin' abdominal muscles. It also might be hard to find many people whose idea of a good time is doing thousands of sit-ups. If you aspire to a flat stomach but don't relish the thought of earning it, you may be pondering just how many sit-ups it will take to do the job.
Are 30 sit-ups a day enough to sculpt you into hard-bellied warrior?
The answer is: yes, absolutely — so long as you throw in the same number of crunches, leg-lifts, planks and other abdominal exercises.
And don't forget the new dietary regimen to lose the excess belly fat that no amount of exercise is going to melt away. Just as there is no Santa Claus, there is no such thing as spot reduction. So add to all of the above a big helping of cardiovascular activity.
Sit-Up Pros and Cons
Sit-ups have their good points, but they've got their drawbacks too. They work the lower abdomen better than crunches, which work the upper abdomen. They work the hip-flexors. That's good as far as it goes. But sit-ups are notoriously hard on the back. Those hip-flexors are some of the strongest muscles in the body, and when they're over-developed to the exclusion of other muscles, the resulting imbalance can cause lower back pain. That's not a problem you encounter so much with crunches.
The fact of the matter is, sit-ups – and to some extent crunches – are no longer considered by many trainers to be the best way to go. (Crunches are basically partial sit-ups, in that the lower back does not leave the ground.) According to the Harvard Medical School, planks – which involve holding a position similar to a push-up for as long as possible – are superior to the old-fashioned sit-up. In fact, in a study of the best ab exercises conducted by the American Council on Exercise, sit-ups didn't even make the list. Crunches, however, did—several times.
Better Than Leg Lifts
But it may be too early to discard the sit-up just yet. A study in the February 2106 Journal of Physical Therapy Science compared sit-ups with leg lifts by using electromyography, which measures the electrical activity of muscle tissue. The sit-up proved to be better in activating the upper and lower rectus abdominis and the external obliques. The researchers concluded that, when done correctly, sit-ups do a good job of working the abdominal muscles without over-involving the lower limb muscles. The key is doing them by curling the trunk while avoiding active flexing of the hips.
For injury-free sit-ups, properly supporting the head and neck is crucial, says Los Angeles-based personal trainer David Knox, author of Body School: A New Guide for Movement in Daily Life. "Your hands support your head to protect the neck. You should never let yourself pull on your head with your hands and shoulders to get your body up." Sit-ups should always be done with the knees bent. Most people find it necessary to have their feet anchored, either by a workout partner or a stationary object--inserting them under the couch is a common way to go -- so the the upper body can rise without toppling backwards.
Anchored sit-ups can increase stress on the lumbar spine, reports Professor Len Kravitz of the University of New Mexico. If you do feel discomfort, don't work through it. Choose an alternative abdominal exercise, such as planks.
- Body School: A New Guide to Movement in Daily Life, by David Knox
- Harvard Medical School: Want a Stronger Core? Skip the Sit-ups
- ACE Fitness: American Council on Exercise (ACE)-sponsored Study Reveals Best and Worst Abdominal Exercises
- Journal of Physical Therapy Science: Comparison of Muscular Activities in the Abdomen and Lower Limbs while Performing Sit-up and Leg-raise