Muscles worked
What the crunch trains
Tap a muscle to see just that one and what it does in the lift.
Before the first rep
How to set up
- 01
Lie down. Lie on your back on a mat with your knees bent and your feet flat on the floor, about hip width apart and a foot or so from your glutes.
- 02
Hands. Rest your fingertips lightly at your temples or behind your ears, or cross your arms over your chest. Your hands support your head; they never pull it.
- 03
Neutral neck. Leave a fist sized gap between your chin and chest, as if holding an orange there. Keep that gap for the whole set.
- 04
Brace lightly. Let your lower back rest naturally on the floor and gently tighten your abs before the first rep.
Step by step
How to do the crunch
- 01
Breathe out and curl. Exhale and curl your head, then your shoulder blades, off the floor by pulling your ribs down toward your hips. Think about shortening the front of your body, not sitting up.
- 02
Stop at the top. Stop when your shoulder blades are just off the floor. Your lower back stays down; this is a short range movement.
- 03
Squeeze. Pause for a second at the top and feel your abs tighten hard. Keep your chin gap the same, and if your hands are at your temples, keep your elbows wide.
- 04
Lower slowly. Breathe in and roll back down over two or three seconds until your shoulder blades touch the floor, keeping some tension in your abs.
- 05
Repeat. Start the next rep without relaxing fully or swinging. Every rep should be a slow, controlled curl.
Cues to say in your head
- Ribs to hips
- Orange under your chin
- Blow the air out
- Shoulder blades up, back down
- Slow on the way down
- Elbows stay wide
Fix these first
Common mistakes
Pulling on your head
Keep your fingertips light at your temples or cross your arms. If your elbows fold in toward your face, your arms are doing the work and straining your neck.
Tucking your chin to your chest
Keep the orange sized gap and look up at the ceiling at a slight angle. The movement comes from your trunk, not your neck.
Sitting all the way up
Stop when your shoulder blades leave the floor. Going higher turns it into a sit up and shifts work to the hip flexors.
Rushing and using momentum
Slow down, pause at the top and take two or three seconds to lower. Fewer controlled reps beat many fast ones.
Holding your breath
Breathe out as you curl up and in as you lower. Exhaling helps your ribs pull down.
Feet lifting off the floor
Keep your feet flat and your legs relaxed. If they keep popping up, you are probably pulling with your hip flexors; shorten the range and slow down.
Stay safe
Crunches are low risk for most people. Stop if you feel sharp pain in your neck or lower back rather than effort in your abs, and check that you are not pulling on your head. Ending a set is simple: stop the rep and lower your shoulders to the floor. If you are pregnant or postpartum, have a hernia, or are dealing with a back injury, check with a doctor or physical therapist first, and get pain that keeps coming back looked at.
Programming
Sets, reps and how much weight
| Goal | Sets | Reps | Load | Rest |
|---|---|---|---|---|
| Muscle | 3 to 4 | 10 to 20 | 60–70% 1RM | 45 to 90 sec |
| Endurance | 2 to 3 | 20 to 30 | 40–55% 1RM | 30 to 60 sec |
| Technique | 2 to 3 | 8 to 12 | 40–50% 1RM | 30 to 60 sec |
Plan your next session
Put in a recent set. You get working weights for your goal, a warm-up and the plates to load.
Estimated 1RM 216 lb
Endurance sets
86–119lb
2 to 3 sets of 20 to 30 reps, 30 to 60 sec rest. Bodyweight only. Keep the same slow curl; stop the set when reps start to get jerky.
Estimates use the Epley formula and work best from sets of 3 to 8 reps. Treat them as a starting point and adjust by how the first working set moves.
Questions
Crunch questions
What muscles do crunches work?
Crunches mainly work the rectus abdominis, the six pack muscle that runs down the front of your stomach. The obliques on your sides help, and because your lower back stays down, the hip flexors do very little.
Crunch vs sit up: what's the difference?
A crunch stops when your shoulder blades leave the floor, so it isolates the abs. A sit up brings your whole torso up to your thighs, which adds the hip flexors and more range. Crunches are usually easier on the lower back for beginners.
How do you do a toe touch crunch?
Lie on your back with your legs straight up toward the ceiling, arms reaching up. Curl your shoulder blades off the floor and reach your hands toward your toes, then lower slowly. Keep your legs still and your lower back on the floor.
How many crunches should I do a day?
You do not need to do them every day. Two or three sessions a week of 3 sets of 10 to 20 slow reps is plenty for most people; add weight when 20 reps get easy rather than doing hundreds.
Will crunches give me a six pack?
Crunches build the ab muscles, but whether you can see them depends mostly on body fat. You cannot spot reduce fat from your stomach, so visible abs come from overall diet and training.
Why does my neck hurt when I do crunches?
Usually because you are pulling on your head or tucking your chin. Keep your fingertips light, hold a fist sized gap under your chin, or cross your arms over your chest.
Train in Protocol
Log your crunch by voice. Protocol tracks the rest.
Your last session shows up before every set, warm-ups and plates are worked out for you, and your coach sees every lift next to your sleep and recovery.