Ahh, plank. Everyone's favorite pose. I don't know too may students who relish lingering in what feels like a torturous pose, and I get it. Plank is demanding and will quickly point out our physical weaknesses to us, but it also yields many benefits when done properly. Plank pose can strengthen the arms, wrists and musculature around the shoulder joint, making it more stable and less prone to injury. It can strengthen the abdominals, back and legs. It's pretty much a full-body workout in just a few breaths.
However, there are some pitfalls we want to avoid when practicing plank so we can stay away from injury. Holding plank properly takes some effort - there's no getting around that. However, the more you practice, the stronger you get, the more ease you can find in the pose. Here's what it generally looks like when done properly:
Notice the fairly straight purple line along the back body (I drew that by hand so perfectly straight was an impossible task). When in plank, you can imagine trying to press the back body against a wall behind you. You want the buttocks, space between the shoulder blades and back of the head to touch that wall. Here's some cueing that can be helpful to understand how to move into and hold this pose:
Once in position (feet hip-width apart, wrists beneath shoulders):
press the floor away with the palms - this will engage the arms and shoulders and "dome" the upper back, drawing the space between the shoulder blades upwards
draw your pubic bone towards your chin - this will "zip up" the abdominals and hug them in towards the midline (an imaginary straight line right down the middle of the body - so you're hugging those abs in)
squeeze an imaginary block between the thighs and then squeeze that block up towards the ceiling - to engage the inner thighs, keep the hips and knees in a neutral position, and spread out the sacrum
draw the heels closer to the mat - to lengthen the back of the legs
reach back through the inner heels - to both engage and lengthen the inner seam of the legs
draw the heart forward - to avoid hunching the upper body
Yeah, there's a lot going on here - but with repetition, which creates muscle memory, you'll get the hang of it and it will eventually become automatic. If a full plank is too intense, supported plank is a great alternative (this is not table pose which students often confuse with supported plank):
Notice the (fairly) straight purple line once again along the back body. Similar cueing here to the full plank:
Once in position (knees and feet hip-width apart, wrists beneath shoulders):
press the floor away with the palms - this will engage the arms and shoulders and "dome" the upper back, drawing the space between the shoulder blades upwards
draw your pubic bone towards your chin - this will "zip up" the abdominals and hug them in towards the midline (an imaginary straight line right down the middle of the body - so you're hugging those abs in)
draw the heart up - to avoid hunching the upper body
Or, if you're feeling energetic, forearm plank works too for sensitive wrists or just to switch things up:
Same straight purple line along the back body, almost identical cueing to regular plank:
Once in position (feet hip-width apart, forearms shoulder-width apart, elbows beneath shoulders):
press the floor away with the forearms - this will engage the arms and shoulders and "dome" the upper back, drawing the space between the shoulder blades upwards
draw your pubic bone towards your chin - this will "zip up" the abdominals and hug them in towards the midline (an imaginary straight line right down the middle of the body - so you're hugging those abs in)
squeeze an imaginary block between the thighs and then squeeze that block up towards the ceiling - to engage the inner thighs and keep the hips and knees in a neutral position, and spread out the sacrum
draw the heels closer to the mat - to lengthen the back of the legs
reach back through the inner heels - to both engage and lengthen the inner seam of the legs
draw the heart forward - to avoid hunching the upper body
Misalignments in plank pose usually occur because we're shifting the body to try and make the pose feel less demanding but in doing so, we're setting ourselves up for possible pain, strain and injury. Case #1: letting the hips droop down so we don't have to engage the abdominals:
There's a lot more weight on the shoulders here than needs to be and the musculature of the shoulder joint isn't really engaged here so we're "hanging" in our shoulder joint instead of engaging muscles and letting them do their job of stabilizing and protecting the joint. The low back is also precariously holding too much weight and is in a hyperlordosis position. We want a bit of a curve in the low back but not that much. This may feel easier but it's not great for the body and in the long run can cause undue strain to wrists, shoulders and possibly contribute to low back pain.
Case #2: Another common misalignment is lifting the hips to avoid engaging the abdominals fully:
There might be a little more engagement of the abs here but we're really not getting the full benefits of the pose and there may be more rounding in the mid and upper back than is necessary. This position may also cause us to let the neck droop down and we already do too much of that looking at our smartphones.
Plank pose probably won't ever make the top 10 favorite yoga poses of all time but it really is a full-body strengthener yielding many benefits and is also a key transitional pose in some forms of Sun Salutations, so we really should focus on proper alignment here. Yoga should enhance and heal, not hurt the body, and when done mindfully, any pose can be beneficial.