According to a physiologist, crunches put stress on your spine, though you can get develop abs . She recommends hanging leg raises. Also develop your overall core muscles, she recommends planks.

Trends and Popularity

The current trend seems to be that planks are more popular than crunches, before crunches however sit-ups were the flavor of the month. So are planks merely another trend in the fitness fashion?

How Different?

Whilst the plank and crunch both work the abs, each one does so uniquely.

The plank requires an isometric contraction, or static holding, of the spine, whereas the crunch requires spinal flexion.

Primary muscles used in the crunch include rectus abdominis, the six pack muscles, and oblique’s, similar muscles used in planks.

However planks also activate muscles in the shoulders, glutes and legs too.

This is important as ¹research by Jinger Gottschall PhD from The Pennsylvania State University, PA shows that abdominal and lumbar muscles are activated more in exercises that require simultaneous activation of the deltoids (shoulders) and glutes.

The Plank, the Winner?

Sounds like the plank is the winner, her research showed that forearm planks active twice the average muscle activity in the rectus abdominus, and external oblique’s than a traditional crunch.

This is the reason that core training as we now know it includes the muscles of the hips and shoulders.

Supporting research includes that of Peter Francis PhD from the School of Exercise & Nutritional Sciences at San Diego State University, San Diego, CA.

His research charted the top 13 abdominal exercises by activation of the rectus abdominus and obliques.

Planks win! but here is the word of caution

The top exercises all include activation in the glutes and deltoids.

Also apparent is that the hover (plank) comes out above the traditional crunch in both categories.

As with all exercises there are progressions of each exercise that need to be compared in further research, but holding a plank for longer is not the best option for a progression according to Dr Wayne Westcott PhD of Quincy College, Quincy, MA.

He states that to build muscle strength, muscle fatigue is needed within the anaerobic energy system, which takes around 60-90 seconds.

The key is how you progress your planks

This means holding a plank for longer is not the solution for core strength!

Good news, this means you can ditch that “6 minute plank plan” and instead work on single-leg progressions to challenge the core dynamically.

Workout smarter, not longer!

The real benefit of planks

The benefit of doing planks however goes far beyond the aesthetic “six-pack abs”.

Traditional crunches may be unsuitable for some to perform due to low back pain, trunk instability or injury, so planks may be a better alternative.

Like all exercises though it’s the attention to detail in the technique that makes plank a challenging core workout.

Plank exercise, when done correctly can really tax the core, but done incorrectly planks can easily send the bulk of the work into the lower back back.

Bottom Line

The bottom line is, are you looking for a flat tummy or just for a stronger core?

Whilst doing any ab exercise will help get you stronger core, research shows that plank exercise will get you a stronger core faster.

However the facts are that ab exercises alone will not get you a flat tummy, diet and exercise go hand in hand in creating flat tummy.