What Are the Benefits of Sit-Ups & Push-Ups?

Sit-ups and push-ups have been the mainstay of home calisthenics routine for decades, and with good reason. Between the two exercises, your core, your upper body and your back are strengthened. And of course there's the great advantage of having a well-rounded workout you can do anytime, anywhere -- great for travel or when you don't have access to a gym.

Sit-ups work the rectus abdominus, where the proverbial six-pack abs reside. (Image: Martinan/iStock/Getty Images)

It might be a stretch to call the two of them a complete workout pair, but understanding the respective benefits -- and limitations -- of each might help you decide how you want to integrate them into your exercise routine.

Sit-Ups the Right Way

When most people think about working their abdominal muscles, they're primarily concerned with the rectus abdominus. That's the long sheath of muscle that, under the perfect conditions of low body fat, high conditioning and the right genetics, can be transformed into the proverbial six-pack abs. While crunches work the upper rectus abdominus and leg-lifts work the lower, done properly, sit-ups can provide some of the benefits of both.

"Sit-ups can do a fine job of working both the upper and lower ends of the rectus abdominus," says L.A.-based personal trainer David Knox, author of Body School: A New Guide to Improved Movement in Daily Life. "But you do have to approach them carefully."

Concerns About Hip-Flexors

On the subject of sit-ups, Knox is an exception to a large chorus of nay-sayers. Detractors feel it's easy for the hip flexors, which connect to the front of the lower spine, to take over the work you want your abs to do. That diminishes ab activation and can strain the lower back, causing pain, especially if your abs are relatively weak. Plus, overworked or too-tight hip flexors can cause a forward pull on the lower spine, resulting in back problems.

Form Is Essential

To avoid these problems, Knox says to make sure your head and neck muscles are completely relaxed and your neck straight. Your hands steady the head, not tug your body upward, which can hurt your neck and is also the main source of detracting from ab work. Your feet should be flat on the floor, shoulder width apart and knees up, Knox says. If you like sit-ups, you can keep your hip-flexors happy with moves like the kneeling hip flexor stretch.

Push-Ups All Around

Many trainers believe push-ups are as close to a perfect exercise as you can get and it's not hard to see why. Push-ups work muscle groups in the chest, arms, back and abdominal area. The push-up remains a long-standing measure of overall fitness by the U.S. military and elsewhere.

Read More: Proper Push-Up Technique

Many trainers consider push-ups one of the best all-around exercises. (Image: Antonio_Diaz/iStock/Getty Images)

The act of pushing is one of five functional movement patterns identified by the American Council on Exercise, which recommends these four moves to help you master the push-up.

Obviously, the ability to use your arms to move things away from your body -- or vice versa -- is quite necessary in every day life. Since strong arms aren't much use without strong pectorals, shoulder and back muscles, the push-up is an all-around great exercise.

It's also one of the best things you can do to improve your posture because it opens and tones the pectorals, which, when weak, can contribute to sagging posture. Push-ups may also help resolve lower back pain by helping to strengthen the transverse abdominus and other core muscles implicated with lower back pain. "Bracing" you abdominals as if you were preparing for a gut punch while doing push-ups will help maximize activation of the core muscles.

Variations on the Theme

By applying various modifications, you can use push-ups to work hard-to-reach muscles. Move your hands closer together and arch your upper back toward the sky, and you have the push-up plus (PUP), also known as anterior serratus push-ups. It's helpful for preventing rotator cuff problems, a hazard of sitting at the computer too much.

Read More: 10 Push-Up Variations for a Stronger Body