Crunches: How to Do It, Muscles Worked & Benefits
Animated demoThe crunch is a classic ab exercise that targets the rectus abdominis, the six-pack muscle. Done slowly and with control, it is a safe and effective way to strengthen the front of your core.
What is the crunches?
The crunch is a classic ab exercise that targets the rectus abdominis, the six-pack muscle. Done slowly and with control, it is a safe and effective way to strengthen the front of your core.
The crunches is beginner-friendly and a isolation movement. Isolation exercises move one main joint, which lets you focus on a specific muscle, fix weak points and add extra training volume without tiring the whole body. You can do it at home with no or minimal equipment, which makes it easy to fit into almost any routine.
Muscles worked
The main muscles trained by the crunches are the abs.
Abs (primary)
The abdominals include the rectus abdominis (the 'six-pack' muscle) and the deeper transverse abdominis. They flex the spine, brace the trunk and protect the lower back during lifting. Visible abs depend mostly on body-fat level, but strong abs improve posture and performance in almost every exercise.
How to do the crunches: step by step
- Lie flat on your back with your feet flat on the ground, or resting on a bench with your knees bent at a 90 degree angle. If you are resting your feet on a bench, place them three to four inches apart and point your toes inward so they touch.
- Now place your hands lightly on either side of your head keeping your elbows in. Tip: Don't lock your fingers behind your head.
- While pushing the small of your back down in the floor to better isolate your abdominal muscles, begin to roll your shoulders off the floor.
- Continue to push down as hard as you can with your lower back as you contract your abdominals and exhale. Your shoulders should come up off the floor only about four inches, and your lower back should remain on the floor. At the top of the movement, contract your abdominals hard and keep the contraction for a second. Tip: Focus on slow, controlled movement - don't cheat yourself by using momentum.
- After the one second contraction, begin to come down slowly again to the starting position as you inhale.
- Repeat for the recommended amount of repetitions.
Coach’s note: Practice the first sessions with a light load or an easier variation. Perfect technique first, then add reps, then add weight.
Benefits of the crunches
- Targets the six-pack muscle directly
- Easy to learn
- No equipment needed
- Good finisher for any workout
Like all resistance training, the crunches also contributes to the general health benefits of strength work: stronger bones, better blood-sugar control, improved mood and a higher resting metabolism over time. The U.S. Physical Activity Guidelines recommend muscle-strengthening activities for all major muscle groups on two or more days per week for adults.
Common mistakes to avoid
- Pulling on the neck with the hands
- Using momentum to swing up
- Lifting too high (turning it into a sit-up)
- Holding the breath
Most of these mistakes happen when the weight is too heavy or when you rush. Film one set from the side with your phone. It is the fastest way to spot form problems without a coach.
Form tips from a trainer
- Hands lightly beside the head or crossed on the chest
- Curl the ribs toward the hips
- Lift only the shoulder blades off the floor
- Exhale as you crunch up
How to breathe
Breathe in while the weight returns to the start position and breathe out as you pull. Keep your ribs down and your core tight so your back stays in a neutral position.
Sets and reps by fitness level
| Level | Sets × reps | Rest | Frequency |
|---|---|---|---|
| Beginner | 3 × 12 | 60–90 sec | 2× per week |
| Intermediate | 3 × 20 | 60–120 sec | 2× per week |
| Advanced | 4 × 25 weighted | 90–180 sec | 2–3× per week |
Choose a load or variation where the last 1–3 reps of each set feel hard but your form stays clean. When you can do the top of the rep range for every set, make it harder: add weight, add reps, slow the tempo or move to a harder variation. This is called progressive overload, and it is the main driver of strength and muscle gains.
Easier and harder variations
Make it easier
- Partial crunches with arms reaching forward
Make it harder
- Weighted crunches
- Cable crunches in the gym
Crunches for men and women
The technique of the crunches is the same for men and women. The difference is in programming. Men often aim for more upper-body size and use heavier loads with lower reps, while many women prefer more lower-body and glute volume and moderate loads with higher reps. Both approaches work. Muscle responds to effort and progressive overload regardless of gender, and women typically recover a little faster between sets.
You will find this exercise in these HelloMyTrainer programs:
Safety tips
- Warm up for 5–10 minutes before your first working set: light cardio plus a few easy reps.
- Stop immediately if you feel sharp, stabbing or joint pain. Muscle burn is normal; pain is not.
- If you have an injury, are pregnant, or have a heart, blood-pressure or joint condition, ask your doctor or a physical therapist before doing this exercise.
- Make sure benches, chairs, steps and bars are stable and can hold your weight.
Frequently asked questions
What muscles does the crunches work?
The crunches mainly works the abs.
Is the crunches good for beginners?
Yes. It is a beginner-friendly exercise. Start with the beginner sets and reps above and focus on clean technique.
How many sets and reps of the crunches should I do?
Beginners: 3 × 12. Intermediate: 3 × 20. Advanced: 4 × 25 weighted. Train each muscle group about twice per week.
Can I do the crunches at home?
Yes, it needs little or no equipment.
How often should I train with the crunches?
Two to three times per week is ideal for most people, with at least 48 hours between hard sessions for the same muscle group.
Related exercises
Animated demoPlank
The plank is a static core exercise in which you hold your body straight on your forearms and toes.
Animated demoReverse Crunches
The reverse crunch curls your hips up toward your ribs instead of lifting your shoulders.
Animated demo
Animated demo
Animated demoDead Bug
The dead bug is a core stability exercise in which you lie on your back and slowly extend opposite arm and leg while keeping your lower back glued to the floor.
Animated demoHanging Leg Raises
Hanging from a pull-up bar and raising your legs is one of the toughest ab exercises.