Crunches vs. Planks

Contributed by Bethany Reynolds, CPT

Are you building strength doing crunches/curl-ups? Crunches are an effective way to strengthen the muscles of your abdomen, specifically the rectus abdominis or what is known as the “six-pack” of your abs. The purpose of the rectus abdominis is to tilt the rib cage and the pelvis toward each other and for trunk stability. The stronger your abs are, the less your spine is forced to work to keep your body upright. If I had time for only one exercise though, I personally prefer a plank to a curl-up. Unlike a curl-up, a plank engages multiple muscle groups, including your rhomboids and trapezius in your upper back, your transverse abdominis, your rectus abdominis, your obliques, and even the abductors in your upper thigh. So to answer the question, yes you are building strength doing curl ups. However, you are building more strength by utilizing more muscles doing planks. According to, planks are safer than crunches, because they don’t require flexion of the spine. If you suffer with disc issues or existing back pain, planks are the safer exercise to perform. The plank pose looks simple but it is challenging and the longer you can hold the pose, the better or more challenging the exercise. I would argue stationary exercises like the plank build muscle that prepares your body for the real world. In the real world we are lifting, hauling, pulling, and dragging. The next time you garden, pick up a young child, re-arrange furniture, put boxes in the attic, or lift heavy grocery bags think about the stability you have in your core from doing planks. Aim for 2 sets of a 30 second plank pose. Build up to 1 minute. Ask your JKFITNESS trainer to time you while holding a plank and reassess in 4 weeks.


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