I'll be the first to admit, I usually don't use planks with new clients.
If you simply put a stick on people's back and ask them to do a plank, you'll likely see a few problems. Here are 7 of them.
1. You don't know whether you should protract your shoulders (or push your shoulders forward).
As a basic test to know whether you should protract your shoulders or not, you should first check the alignment of your scapulae or shoulder blades. Measure the distance from the middle of the scapula to the middle of your spine. It should be about 2.5 inches to 3 inches.
If you are beyond 3 inches, avoid protracting your shoulders. You will only create an abducted scapula position. If you are from 2.5 to 3 inches, you can protract your shoulders, but you should balance it out with some form of scapula retraction. If you are at 2.5 inches or below, you definitely need to protract.
The problem is that many individuals don't really know what their scapula alignment is.
2. Many individuals will have pain in the elbow, shoulder, or neck area simply being in a plank position.
Some individuals who have had recent trauma, are overweight, had chronic injuries, or simply have pain in these areas should be careful with planks.
If you are not overweight, and you loaded up 50 pounds for a one minute plank, think how that would feel. You might be able to do it without pain, but that is a lot of stress on the elbow and shoulders.
3. They can't achieve a neutral lumbar spine.
Their is likely a greater than one inch space between the lower back and the stick. If this is the case, the person cannot maintain a basic neutral pelvis.
The only way you will get out of anterior pelvic tilt is by maintaining and reinforcing a neutral pelvic position.
A regular floor plank for many individuals is too intense. A proper progression is to begin with a plank with forearms on a bench. It already places the hips in hip flexion and helps to flatten out the lumbar spine.
A person can then progress down to the floor, and eventually have a weight on their back, use an ab wheel, or use a long plank with the arms more overhead. Before you use these exercises however, I usually see problem number 4 rear it's ugly head.
4. Individuals quickly lose neutral pelvic posture (or don't have sufficient core endurance).
Have you ever seen plank contests for time? Have you noticed by the end of the contest that individuals look like they finished with an invisible person sitting on their low back?
You need to use a stick and monitor the space under the low back from beginning until the end. If you think you can hold a plank for two minutes, you need to be able to maintain a neutral pelvis for that long.
5. The head is not neutral.
With a stick on the back, most individual's heads look like this:
When you try to have them correct it, it then looks like this:
The reality is that the ground is too advanced for them. What you will need to do is to start off higher like putting your forearms on a bench like this.
6. Thoracic kyphosis prevents a neutral thoracic or head position.
All this means is that the upper back may be so rounded that the head and the upper back can't be neutral.
I'm a big fan of eliminating flat thoracic spines, but they often accompany thoracic kyphosis, so it is wise to address both of them.
Although we haven't dealt yet with thoracic spine corrections, it can seriously help to perform some thoracic extensions or side lying thoracic rotations before you get into your plank. This may allow your upper back and head position to be neutral or at least be closer to neutral.
7. You can't breathe with the stick on your back.
You need to breathe into your back. Because of this, the stick should rise slightly above your head on your inhale, and fall back onto your head on the exhale. If you see someone who keeps the stick stationary on their head, it means their not expanding their back which they should.
The floor plank is an intense exercise. It includes a lot of components like proper head and thoracic posture, and proper breathing. Make sure you get all these components under control before you advance.