Crunch

VeryWellFit: "Crunches have been the mainstay of ab workouts for decades. They target the rectus abdominis, the six-pack muscle that runs along the front of the torso. Crunches can be part of a core strength workout or a total body workout." [ID: crunch]

Instructions

First time: Do 1 set, 12 reps, put your arms across your chest

Steps:

Start position: Lay on your back. Place your hands across your chest or behind your head (a little tougher).
Engage your core (abs, glutes) and raise your shoulders off the ground. Exhale as you crunch your abs at the top.
Return to start; rinse and repeat

Don't perform a full sit-up. Rather, the crunch only involves lifting the shoulder blades off the floor. This limits recruitment of the hip flexor muscles and may be safer for the low-back.

Details

Remember: Slow down, breath.

Common mistakes: Don't strain your neck. Don't raise your shoulders too much. The crunch is a subtle movement, so just lift the shoulder blades a few inches off the floor.

Crunch with dumbbell is a popular (and fun) progression. Video demo: www.youtube.com/watch?v=wngf6BI012Y

Crunch variations:

Bicycle crunch - personal favorite, bicycle_crunch.htm
Side crunch - lying on your side, side_crunch.htm
Crossover crunch - cross one leg over the other knee, crossover_crunch.htm
Reverse crunch - raise legs, reverse_crunch.htm
Vertical leg crunch - raise legs and crunch, www.verywellfit.com/vertical-leg-crunch-3120071
Big ball crunch
Sit-up - pull all the way up, www.youtube.com/watch?v=swOyWKk7Oko
V sit/sit-up - raise legs to crunch and form a V shape, v_sit.htm
Accordion crunch - rise up on both ends, your shoulders and your knees, and bring them together (like an accordion), www.youtube.com/watch?v=dcQ5Zhbkem0

Little help

Video: demo by Bowflex, www.youtube.com/watch?v=0OxOI3sAIrM

Article: "How to Do an Abdominal Crunch" by VeryWellFit, www.verywellfit.com/how-to-do-a-perfect-abdominal-crunch-1229513

Video: "5 of the Easiest At-Home Exercises" by BowFlex, www.youtube.com/watch?v=pS7ohYO2Bz8

Video: demo of crunch with dumbbell, www.youtube.com/watch?v=wngf6BI012Y

Article: "Crunches: How to do them and 3 crunch variations for the best ab workouts" by TomsGuide, www.tomsguide.com/how-to/crunches-how-to-do-them-and-3-variations-for-your-abs-workout

Article: Abs exercise/Crunch by Ace fitness, www.acefitness.org/resources/everyone/exercise-library/52/crunch

Image source: VeryWellFit, verywellfit link