Believe it or not the best exercise to improve core strength is not the crunch. It’s the PLANK!
Planks work far more muscles than a crunch does, and planks work muscles in a different way. In a plank, your muscles contract isometrically (without joint movement) and your shoulders, abs, back, gluts and legs are all actively working to hold your form in the pose. In a crunch, your muscles contract concentrically on the curl-up (muscle shortening) and eccentrically on the release (muscle lengthening). Isometric exercises tone muscle and concentric/eccentric exercises increase muscle size.
How to do a plank:
Planks are not simple. Planks require a good amount of shoulder and core strength (core meaning both abs and back). Anyone with joint issues, back pain or overall core muscle weakness should carefully work up to the plank exercise, with approval from their doctor. Anything other than perfect form on a plank position poses a risk to straining the spine.
- Get down on the floor, resting on your forearms and knees (or forearms and hands).
- Curl your toes under, raise your knees off the floor and straighten your legs.
- Contract your abs (but don’t hold your breath) and keep your body perfectly straight like a board. Do not stick your butt in the air or allow your hips to sag below knee level.
- Keep your eyes on the floor in front of your hands. Do not tuck your head.
- Hold for 20 seconds, then rest. Repeat 3x.
- Practice planking 3 times per week, resting in between on “off days”.
Slowly increase planking time until you can hold your perfect-form plank for 1-2 minutes. At that point, it’s time to move on to a more challenging version (single leg, single arm, high side plank, stability ball, weighted, extended… the possibilities are endless!)
Meanwhile, keep crunching!
Crunches (partial sit-ups) are still a great way to build abdominal strength. Even tho they don’t work as many muscle groups (primarily abs and little bit of legs), they are still a solid exercise that can be done in combination with planks to improve core strength. There are tons of variations of crunches which make them suitable for all levels, beginner to advanced.
Bottom Line: The core is like any other muscle group, and should rest on “off days” in order to rebuild stronger. Workouts are more fun with variety so consider adding some planking to your routine, to recruit more muscles and tone the core. And never forget that diet is much more important than exercise when it comes to showing off that 6-pack! Fat-burning cardiovascular exercise should always be part of your routine.