July 11, 2026, 4:02 pm | Read time: 3 minutes
A classic among abdominal exercises: the sit-up. However–as I recently learned from a personal trainer–many people don’t even know how to distinguish them from another abdominal classic, the crunch. The two exercises are often confused. This often leads to a misjudgment of the difficulty level of sit-ups. Even though beginners at the gym may have heard or read about sit-ups, the exercise is not ideally suited for them. Find out why at FITBOOK.
For crunches and sit-ups, you don’t need much: just a mat so you don’t have to do them on a hard surface. That’s why these bodyweight exercises have been popular for decades to shape the abdomen. While there are more effective ways to achieve the desired six-pack, crunches and sit-ups certainly have their place.
As part of a diverse workout routine, they isolate the rectus abdominis muscles and help define them–if done correctly. Sit-ups, in particular, can be an unexpected hurdle for beginners because they look simple but are often performed incorrectly, rendering them almost ineffective.
Difference Between Crunches and Sit-ups
The names of the exercises already provide good clues about the central difference. In a crunch, you move your upper body toward your bent knees with your abs engaged (you may have heard the phrase “pull your navel inward”). You essentially press your abdominal muscles together. Only the shoulders and, at most, the upper back lift off the ground. The lower back remains on the mat.
It’s different with the sit-up. Here, you move from a lying position to an upright sitting position. This means you have to lift your back completely off the ground.
Why Sit-ups Aren’t the First Choice for Beginners
Both exercises should be performed in a controlled, slow manner without momentum. Only when the movement is purely driven by the abdominal muscles do they effectively train them. Using momentum primarily engages the hip muscles, which is not helpful if the goal is to tone the abdomen.
With proper technique, sit-ups become particularly challenging. To perform them correctly (without momentum), you need a strong core. You may have seen in the gym that someone holds the feet of the person doing sit-ups. This assistance can help the exerciser focus entirely on their upper body. However, it is ineffective if used to simply swing into a sitting position. While the exercise may look correct and impressive to laypeople, it doesn’t train the abdominal muscles.
Crunches are clearly the smarter choice for beginners because they require less abdominal muscle engagement. They are well-suited for starting abdominal training. By incorporating exercises like leg raises or squats (where the abdominal muscles are required for stabilization), one can gradually strengthen the core to the point where sit-ups become an achievable challenge.