How to Do Sit-Ups: Benefits, Muscles Worked and Alternatives

When most people think of a strong core or achieving abs, the first exercise that comes to mind is often sit-ups. While sit-ups have long been a go-to for strengthening the core, they’re not always the most effective or safest option for everyone. Proper form and technique are key to maximizing the benefits of sit-ups while avoiding strain on the back and neck.

To provide a well-rounded perspective on how to do sit-ups, we spoke with three experts who shared their insights on the benefits and potential risks of sit-ups, as well as alternative exercises that can help build a strong core without the same level of stress on the body. Their advice offers a balanced view of how to approach core training, ensuring safety, effectiveness, and overall fitness progress. Whether you’re a beginner or a seasoned athlete, understanding how to incorporate sit-ups — or how to replace them with other movements — can help you reach your fitness goals more efficiently and safely.

Many expectant mothers, especially, wonder if sit-ups are safe during pregnancy and whether they should incorporate them into their fitness routines. To provide expert guidance, we spoke with a specialist who will weigh in on the safety and recommendations for core exercises during pregnancy.

Experts Featured in This Article:

Leia Rispoli, MD, is a double board-certified interventional pain management specialist and physiatrist at DISC Sports & Spine Center.

Anna Larson, PT, DPT, is a doctor of physical therapy at Fusion Wellness and Femina Physical Therapy in Los Angeles, CA.

Meleen Chuang, MD, is a clinical associate professor for the Department of Obstetrics and Gynecology at NYU Grossman School of Medicine, chief of Obstetrics and Gynecology at NYU Langone Hospital Brooklyn, and medical director of Women’s Health, Family Health Centers at NYU Langone (FHC).

Todd Sinett, DC, is the CEO of Tru Whole Care and founder of Backbridge, a back pain device. Dr. Sinett has published four books on treating back pain, available on Amazon.

Sit-Ups: Muscles Worked and Benefits

Most people might assume crunches and sit-ups are the same exact exercise. However, there are a few key differences to note for each movement, particularly when it comes to the muscles involved. “While the terms ‘crunches’ and ‘sit-ups’ are sometimes used interchangeably, sit-ups are usually hinged from the waist, and crunches can be more of a curling of a spine, but it really depends on who you talk to and how people use these terms,” Leia Rispoli, MD, says. “Classically, a crunch is more of a curled movement from a flat position where your elbows meet your knees vs. a sit-up, which is a hinge from the waist with a persistent stable and flat spine.”

When it comes to performing sit-up exercises, the main muscles used are the rectus abdominis, obliques, transverse abdominis, and hip flexors. “The specific muscles that are worked and utilized involve your core muscles (mostly your anterior core muscles), so all your abdominal muscles, and hip flexor muscles,” Dr. Rispoli says.

A sit-up exercise “involves your abdominals and hip flexors as well because it combines spinal flexion and hip flexion,” Anna Larson, PT, DPT, says. “While crunches involve mostly your abdominal muscles, because the motion is achieved only with spinal flexion.”

There are benefits of sit-ups that relate to movements in everyday life. “A lot of core muscle strength and stability helps protect and preserve the spine,” Dr. Rispoli says. “In general, this helps establish a persistent habit of good posture, which ultimately puts the spine in a protective mode against years of degeneration.”

“Our abdominal muscles form a large part of our core, which give us stability, balance, and improved posture,” Dr. Larson adds. “Strengthening your abdominal muscles also will increase your pelvic floor strength. Improved pelvic floor strength will help to decrease the risk of urinary incontinence and prolapse.”

How to Do Sit-Ups Safely

Some might want to start out with both hands behind your neck, but for safety, try to keep the arms crossed at the chest first, especially if you’re a beginner. “You want to keep your lumbar spine and your neck and your head all in one plane,” Dr. Rispoli advises. “You don’t want to put any extra flexion or strain on the neck, and you don’t want to use your arms that are positioned behind your head to hinge your neck in a flexion position and pull from there.” She adds: “If the initial engagement of the muscles is too difficult to get off of the floor immediately for those first few degrees, then you should use some sort of propped mat to help eliminate those first few degrees of difficulty.”

Note for beginners: “When starting out with this exercise, it is helpful to have someone stabilize your feet or place your feet under something sturdy such as a couch,” according to Dr. Larson. “Placing a small ball or a couple of pillows behind the back can help to engage the deeper abdominal muscles and help increase your strength gradually over time.”

“The best starting position is with a pillow behind the back or small ball, as this will help encourage spinal flexion, and the engagement of the abdominals instead of overrecruiting the hip flexors. This also decreases the load to the neck as the angle takes some of the strain from the neck muscles and focuses more on the abdominals,” Dr. Larson adds.

Sit-Up Alternatives

Todd Sinett, DC, believes you can do much more than sit-ups to help your core. “I wrote a book entitled ‘Sit-Ups Are Stupid and Crunches Are Crap,’ which provides an outline of exercises and stretches that help to strengthen our core,” he says. “To name a few I love: dead bugs, bird dog, leg raises, planks. You want to focus on exercises that elongate the body and spine.”

Dead bugs: “Anything laying on your back while alternating moving your legs or arms, such as a dead bug, is a great way to build deep core strength,” Dr. Larson says.

Bird dogs: “Another way to challenge core stability is on hands and knees alternating reaching your opposite arm and leg, also called a bird dog.” Dr. Larson adds.

Leg raises or planks: For pre- or post-natal women, “pelvic tilts, modified planks, leg raises, side-lying exercises can help strengthen core while also ensuring safety during pregnancy. Light aerobic exercises, weightlifting, moderate brisk walking, and cycling on a stationary bike are good options,” Meleen Chuang, MD, says.

Pelvic tilts: “An alternative exercise can be something like a pelvic tilt, where you’re in a sit-up position, but instead of raising your upper trunk, you’re just flattening your back to the floor and contracting and engaging your core and abdominal muscles,” Dr. Rispoli, MD, says.

Jade Esmeralda (she/her), MS, CSCS, is a health and fitness staff writer and a strength and conditioning specialist. A lifelong martial artist and dancer, Jade has a strong passion for strength and conditioning, sports science, and human performance. She graduated with a Master of Science degree in exercise science and strength and conditioning from George Washington University.