Exercise guide

Crunch: muscles worked and how to do it

The crunch curls your head and shoulders up off the floor by shortening your abs, while your lower back stays down. GymTribe's library lists it as Floor Crunch, with the upper abs as its target muscle.

Illustration of a crunch, showing the start and end positions

How to do a crunch

Lie on your back with your knees bent and your feet flat on the floor.
Rest your fingertips lightly behind your ears or cross your arms over your chest.
Breathe out and curl your head and shoulders off the floor, bringing your ribs toward your hips.
Stop when your shoulder blades are just off the floor, and pause.
Lower back down under control.

These steps describe common technique. If something hurts, stop and ask a qualified coach or clinician.

Common crunch mistakes

Pulling on your neck
Keep your hands light. Your abs lift you, not your arms.
Sitting all the way up
A crunch is a short curl. Your lower back stays on the floor.
Rushing
Pause at the top and lower slowly, so each rep counts.
Chin jammed to chest
Leave a fist's space between your chin and chest.

How to track your crunch

Log the reps of every set. Over a few weeks, your most reps in one set and in one session show whether you are getting stronger. When you add weight, log it with the reps.

What GymTribe charts for Floor Crunch

Most reps in one set
Max session reps across a workout
Heaviest weight once you add load
Estimated 1RM once you add load

Strength tracking in GymTribe →

Crunch questions

What muscles do crunches work?

Mostly the upper part of the rectus abdominis, the abs muscle down the front of your stomach, with the obliques helping. In GymTribe's muscle map, each set of Floor Crunch counts toward the upper abs.

Crunch or sit-up?

A sit-up comes all the way up, so your hip flexors do more. The crunch stops with your lower back on the floor, so it stays on the abs.

How do I make crunches harder?

Slow down, pause longer at the top, or hold a plate on your chest and log its weight. GymTribe also lists Reverse Crunch, Bicycle Crunch and Kneeling Cable Crunch as their own exercises.

How do I track my crunch in GymTribe?

Log each set's reps under Floor Crunch. Every session adds a point to its charts, including most reps in one set and max reps in a session, and a New PR alert appears when a set beats your rep record. If you add weight, log it too, and the heaviest weight and estimated 1RM charts fill in.

More upper abs exercises in GymTribe

GymTribe counts these toward the upper abs too. The ones with a guide are linked.

Kneeling Cable Crunch
Supine Toe Touch
Weighted Decline Sit-Up
Seated Ab Crunch Machine
Decline Bench Sit-Up
High Cable Kneeling Crunch
Stability Ball Crunch

More core guides

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