Sit-ups also known as Curl-up is a bodyweight exercise consisting of lying down on the floor and curling your torso toward your thighs by using your rectus abdominis muscle. The main goal of this movement is to strengthen your entire core region, with a secondary benefit of improving lower back strength.
A crunch is an abdominal endurance training exercise to strengthen and tone the abdominal muscles. It that begins with begins with lying face up on the floor with knees bent and feet planted on the ground. The movement begins by curling the shoulders towards the pelvis. The hands can be behind or beside the neck or crossed over the chest.
Key Difference
The Right Way of doing it
For proper crunch, lay on your back with knees bent and feet on the ground. Only lift your head and chest off the ground until you feel the abdominal muscles engage, then lower your head back down. Do not jerk your head; place hands either loosely on your chest or finger tips on your ears.
On the other hand, for a proper sit up, lay with your back on the ground, knees bent and feet on the ground. Cross arms over the chest or place finger tips behind your ear. Bring head and chest up to full sitting position, without jerking the head. Neck should be slightly flexed forward. Return head all the way to the ground and repeat.
Muscles Involved
Crunches mainly exercise the abdominal muscles and the hip flexors whereas, sit-ups engage muscles that stabilize posture such as chest, back, neck, lower-leg muscles and hips.
The Lower Back
With crunches, the lower back doesn’t lift off the ground whereas in sit-ups, the whole body rises.
Risk involved
With sit-ups there is a high risk of injuring the back especially when your abs are weak because full sit-ups involve the hip flexors, which may cause the lower back to arch, causing pain. On the other hand, Crunches are safe exercises which can be performed by anybody.
Calories Burn
Sit-ups burn more calories than crunches, however if the both techniques are not followed properly there will be no burning of calorie (spot reduction of fat).
Recommendations
If you want to do crunches as part of your workout routine, it is recommended that you stick to a moderate amount like you would with any other exercise and in this regard, three sets of 10 to 12 repetitions is generally sufficient. Now, when it comes to sit ups, it is recommended that you combine three sets of sit-ups with 25 to 50 repetitions per day.
Also Read: Difference Between Yoga And Pilates
Difference Between Crunches And Sit-ups In Tabular Form
| Basis of Comparison | Crunches | Sit-Ups |
| The Right way of Doing it | For proper crunch, lay on your back with knees bent and feet on the ground. | For a proper sit up, lay with your back on the ground, knees bent and feet on the ground. |
| Muscles Involved | Crunches mainly exercise the abdominal muscles and the hip flexors. | Sit-ups engage muscles that stabilize posture such as chest, back, neck, lower-leg muscles and hips. |
| The Lower Back | With crunches, the lower back doesn’t lift off the ground. | In sit-ups, the whole body rises. |
| Risk Involved | Crunches are safe exercises which can be performed by anybody. | With sit-ups there is a high risk of injuring the back especially when your abs are weak because full sit-ups involve the hip flexors, which may cause the lower back to arch, causing pain. |
| Calorie Burn | Crunches burn less calories. | Sit-ups burn more calories. |
| Recommendations | Three sets of 10 to 12 repetitions. | Three sets of sit-ups with 25 to 50 repetitions per day. |
Summary
What is the main difference between Crunches and Sit-ups?
While in both cases, the exercise is done while lying down, however, with crunches, the lower back doesn’t lift off the ground whereas in sit-ups, the whole body rises.