Is Plank a Great Exercise for Building Strength?

I've been thinking about isometric exercises, such as plank pose, for months now. Finally, I did a little research and learned more about the benefits and lack thereof.

Isometric exercises employ a static contraction of a muscle or muscle group. This means that the muscle(s) involved may be tensing (tightening, contracting) but there is no movement at the joints, no shortening or lengthening of the muscle(s), and no movement through space. Plank pose is a perfect example of a static position which is held. The core muscles are working to maintain the position against the pull of gravity, but no movement is occurring. Wall sits, where a person rests the spine against a wall and bends the knees to 90 degrees with the thighs parallel to the floor, are another example.

I've been wondering why we do these isometric exercises. Are they better, in any way, than a dynamic or moving version of the same position? For instance, why would we choose to execute a static plank instead of a series of push-ups? Same position, but a push-up moves up and down while a plank stays still. And why do a wall sit instead of a squat? Is there any reason?

After reading the results of a Mayo Clinic study of isometric exercises, I discovered that they are NOT as effective as dynamic exercises for strengthening a muscle or muscle group. I was not surprised to learn this. Because a position is being held in stillness, there is zero range of motion for the muscle(s) involved. So only a very small portion of the muscle's fibers are being used. (In my own teaching, I have witnessed students who are able to hold a plank for many minutes but are unable to execute various types of sit-ups. This tells me that holding that plank is not doing the job of strengthening the abdominals! And if the benefit of holding in a static position doesn't translate into dynamic strength, how effective can those exercises be?)

NASA also tested isometric exercises on astronauts in space to combat muscle atrophy due to lack of gravity. The tests revealed that isometrics aren't very effective, even in this capacity. Astronauts who performed isometric exercises in space continued to lose muscle rather than maintain it.

So does that mean you should give plank pose the boot? Kick it to the curb? Banish it from your workout?

That depends. Isometrics are better than nothing! And they have been shown (in the Mayo Clinic study) to lower blood pressure. So they may have an important place in rehabilitation after injury or surgery, or for those who are unable to perform dynamic exercises. They have also been shown to be effective for people suffering from arthritis, where joint movement might be too painful for dynamic exercises.

But for those of us who seek fitness, holding a plank for five minutes (or five hours, as is the world record!) is probably a big waste of time. You will get much stronger, much faster, by spending your precious workout minutes on dynamic (moving!) exercises. Stick with the basics like push-ups, pull-ups, squats, lunges, sprints, and burpees. Moving your whole body through space will get your heart rate up, burn loads of calories, and tax your muscles enough to build strength throughout the body's complete range of motion. Plank pose, not so much.