Oh the plank. perhaps one of the most deceiving exercises out there. It looks so simple, but somehow it challenges more than you would expect. The good news about the plank is that it is a very effective core exercise and is very easy to modify - I mean, extremely easy.
The plank is what's known as an isometric exercise - meaning that you produce force without movement. While simple in design, the plank forces activity of about a dozen different muscles. The plank will target the rectus abdominis (your 6-pack) and the following muscles as stabilizers:
|iliopsoas||erector spinae||pectoralis major|
So, why is the plank such a good body weight exercise? Well, as you can see above, there is a huge amount of muscle activity, especially in your core. A strong core is very important - it will act as a girdle to product and support your organs; as well as promote better posture, protect your spine, and support you during reaching activities. Not only does the plank activate the core, but it also activates stabilizing muscles in your upper back and hip flexors. All of this is important in maintaining good posture and alignment.
Secondly, as I've mentioned above, the plank is easily modified, and can follow the progression seen below.
The plank can also be modified into a side-plank, which targets the obliques, rather than the rectus abdominis and will uses close to 20 stabilizing muscles, including the gluteals and the pectorals.
Remember when doing a side plank that you have to do it on both sides to avoid muscles imbalance.
Finally, the plank requires not one single piece of equipment. if you have a free bit of floor slighter longer than you are tall, you can do a plank.
One thing the plank will not do is get rid of the fat around your belly, nor will sit-ups, and nor will crunches. This is because there is no such thing as spot reduction, but that's a topic for another post. What it will do is give your core a heck of a work-out without moving an inch.