When many boys exercise their abdominal muscles, the first exercises that come to mind are crunches and sit-ups. These two exercise methods may look the same, but there are some subtle differences. So what are the differences between them?
Different movements
Crunches: During crunches, the body lies flat on a mat, stabilizing the lower limbs, and the hands are placed in front of the chest or by the ears. The starting position is with the shoulder blades flat on the mat, and the finishing position is with the shoulder blades off the ground. The waist and lower limbs remain stable throughout the training, and the entire movement involves bending the spine forward. In professional terms, we call this movement "trunk flexion."
Sit-ups: During sit-ups, in addition to the shoulder blades leaving the ground, the waist also lifts off the ground, and the body sits up. At this time, the body not only performs a forward "trunk flexion" movement, but also the angle of the hip joint becomes smaller, accompanied by a "hip flexion" movement during the exercise.
Different muscles involved
Crunches: The rectus abdominis muscle starts at the pubic bone and ends at the sternum and ribs. Therefore, the rectus abdominis muscle is the main force exerted during the "trunk flexion" movement, so the main muscle involved in doing crunches is the rectus abdominis muscle.
Sit-ups: When the human body does sit-ups, both the shoulder blades and the waist leave the ground, and the body sits up. The main muscles involved in this process are the rectus abdominis muscle and the iliopsoas muscle.
Different suitable populations
Crunches: Crunches have a strong targeted effect and mainly strengthen the rectus abdominis muscle. Therefore, it is particularly suitable for people who want to exercise their abdominal muscles.
Sit-ups: Sit-ups mainly exercise the iliopsoas muscle, so they are especially suitable for people who want to exercise their iliopsoas muscles.
Which is more effective, crunches or sit-ups?
Crunches are more effective for abdominal muscle training.
Crunches mainly exercise the rectus abdominis muscle, which is the central muscle in the abdomen. During crunches, the hips are fixed, and the main force comes from the contraction of the abdominal muscles, causing the upper back to lift off the ground. Therefore, crunches can effectively exercise the abdominal muscles.
Sit-ups are more effective for iliopsoas muscle training.
Sit-ups are a movement that involves the thoracic vertebrae, lumbar vertebrae, and hip joints. Especially when sitting up, the main force comes from the iliopsoas muscles, so sit-ups have a significant effect on exercising the iliopsoas muscles rather than the abdominal muscles.
