Crunches: Complete Exercise Guide

Overview

Crunches are a classic abdominal exercise that isolates the rectus abdominis. When performed correctly, they're an effective way to build core strength and muscular endurance.

Difficulty Beginner
Category Core
Equipment None (Bodyweight)
Calories/Min ~5
Tracked by Fitnit Yes - AI Rep Counting

How to Perform Crunches

  1. Lie on your back with knees bent and feet flat on the floor
  2. Place your hands behind your head or across your chest
  3. Engage your core and lift your shoulder blades off the floor
  4. Curl your upper body toward your knees with controlled movement
  5. Slowly lower back to the starting position

Form Tips

  • Don't pull on your neck with your hands
  • Focus on curling your ribcage toward your pelvis
  • Keep your lower back pressed into the floor
  • Exhale as you crunch up, inhale on the way down
  • Maintain a fist-sized space between your chin and chest

Common Mistakes to Avoid

  • Pulling on the neck with hands causing strain
  • Using momentum instead of controlled movement
  • Lifting too high and engaging hip flexors
  • Not maintaining tension throughout the movement
  • Holding breath during repetitions

Variations

Reverse Crunch

beginner

Lifting hips toward chest targeting lower abs

Bicycle Crunch

intermediate

Alternating elbow to opposite knee

Cable Crunch

intermediate

Using cable machine for added resistance

Decline Crunch

intermediate

Performed on decline bench for increased range

Weighted Crunch

advanced

Holding weight plate on chest

Benefits of Crunches

  • Targets the rectus abdominis specifically
  • Low impact and beginner-friendly
  • No equipment required
  • Can be performed anywhere
  • Good for building ab endurance

Muscles Worked

Primary Muscles

Rectus Abdominis

Secondary Muscles

Obliques

Frequently Asked Questions

What muscles do crunches work?

Crunches primarily target Rectus Abdominis. Secondary muscles engaged include Obliques. This makes crunches an effective exercise for building strength in multiple muscle groups.

Are crunches good for beginners?

Yes, crunches are an excellent beginner exercise. They require no equipment and can be scaled with easier variations like Reverse Crunch. Start with proper form at a comfortable level and progressively increase difficulty.

How many crunches should I do per workout?

For strength building, aim for 3-5 sets of 6-12 reps of crunches. Beginners should start with 2-3 sets of as many reps as they can with good form. For endurance, try higher rep ranges of 15-20 per set. Fitnit can automatically count your reps and track your progress over time.

How many calories do crunches burn?

Crunches burn approximately 5 calories per minute, though this varies based on body weight, intensity, and fitness level. A 10-minute session of crunches can burn roughly 50 calories. For accurate tracking, Fitnit monitors your actual workout intensity and duration.

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