The Benefits of Doing Planks

Put simply, the plank is an isometric body-weight exercise that boosts core endurance. (Isometric means that there’s no movement involved.) Note that we said endurance, not strength. “Planks — as with any good core exercise — do not work on strengthening, but work to improve muscle endurance,” says Marian Barnick, a registered kinesiologist and cancer movement therapist in Toronto.

While muscle strength refers to the amount of force a muscle can exert or how much weight you can lift, muscle endurance refers to the ability of a muscle to hold a sustained contraction for a longer period of time. You need both to keep muscles in their best shape: Strength gives you the power to exert a maximal force (think lifting a heavy box) and endurance means you can continue using your muscles over and over again before they fatigue (as you would do while running a marathon or performing several dozen repetitions of an exercise).

When it comes to our core muscles, improving endurance can help with many daily tasks, Barnick explains. “Our core helps us maintain our posture, supports our spine, and keeps us aligned while we’re sitting, standing, and walking.” (And yes, it will contribute to a stronger-looking core, too.)

Planks work a range of muscles. In a plank, you’ll predominantly be using the transverse abdominis and rectus abdominis muscles of the abdominal wall, says Cameron Yuen, CSCS, a doctor of physical therapy and practicing physical therapist at Bespoke Treatments, a New York City– and Seattle-based physical therapy practice. It’s the group of muscles on the front side of your abdomen: “The rectus abdominis is the most superficial muscle and creates the ‘six-pack look,’ while the transverse abdominis is the deepest abdominal muscle,” he explains.

Planks also work your glutes, both maximal and medius, notes Darryl Whiting, a group fitness instructor at Equinox. (You may hear a fitness instructor tell you to focus on tightening your glutes in a plank.)

Which other muscle groups are worked will depend on which type of plank you’re doing. When you plank on your forearms (more on this below), you’ll generate more tension through the core and lats — the latissimus dorsi muscles, which are the large V-shaped muscles connecting your arms to your spine and back. If your goal is purely to work your core, the forearm plank is the one to do.

When you do a plank with arms fully extended (the top of a push-up position) you also work your triceps, shoulders, and chest.

How to Do a Proper Plank: Correct Form and Variations

To do a forearm plank:

Start in an all-fours position with hands and knees on the ground.
Place your elbows on the floor directly beneath your shoulders so your arms form a 90-degree angle and look straight down toward the floor.
Extend one leg at a time behind you while maintaining a neutral spine (holding the same natural curve in the upper, mid, and lower spine that you would have if you were standing up straight), and contract your glute muscles to reinforce the straight line from the crown of the head to the heels. Avoid overarching your lower back, hiking your hips upward, or bending the knees.
Contract your abdominal muscles — it should feel as if you are tightening the entire area between your ribs and pelvis.
At the same time, contract your lats by pushing your elbows against the ground as if you are trying to bring your elbows to your toes.

To do a straight-arm plank:

Start in an all-fours position on hands and knees.
Keeping palms flat on the ground and your gaze toward the floor, step your feet back to form a perfectly straight line from the crown of the head to the heels. (Your gaze should be focused downward so your neck is straight, too.) Hands should be directly beneath your shoulders.
Keep your neutral spine position while contracting your abdominal muscles, lats, and glutes, as described above.

To do a modified plank on your knees:

Start in an all-fours position on hands and knees.
Walk hands forward and keep the knees touching the ground, until your body forms a straight line from the top of your head to your knees. Keep your spine in neutral alignment.
Engage your core and lat muscles to hold the position. Your gaze should be downward and slightly out so that your neck is aligned with your spine.

How Long and How Often to Perform Planks

Here's a good goal: Aim to hold a plank for between one and two minutes, Yuen suggests. “This isn't arbitrary, as this is roughly how long most exercise sets last, and you want your core to at least be strong enough to maintain a neutral spine for this amount of time, since this is when your spine is under the most load.”

It is safe to do planks daily, barring any injuries, heart conditions, or strain on the shoulders. “Since planks work muscle endurance, not strength, there’s no need to let the muscles rest and repair prior to working them again,” notes Barnick.

“The plank is safe for most people, but if you are new to exercise, it is always prudent to make sure you are cleared by a medical professional and have a fitness professional look at your form,” Yuen says. In particular, if you have high blood pressure, a hard abdominal bracing maneuver might temporarily further increase your blood pressure. Certain spine conditions might also be aggravated if you hold the plank in an overly flexed or extended position.

Tight hip flexors may cause problems as well, Barnick says. Our core may become weak and we may lose a neutral spine position because of tightness in the hip flexors. If your hip flexors are tight, when you try to plank, you won’t benefit core muscles and you’ll continue to stress the hip flexors, which really need to be stretched, not engaged.

Finally, any issues with your shoulders may need to be treated before you work on planks. “It’s imperative to keep stress off the shoulder joint by keeping the arms in a proper position, allowing the stabilizer muscles to do their job,” Barnick explains.

You may have dealt with any of these issues or have another health condition or illness that might prevent you from working out safely. Even if you haven't, it's always a good idea to check with your healthcare provider before you start a new exercise routine.