Plank Jacks: What They Are and How to Perform Them

By combining two popular exercises—jumping jacks and planks—plank jacks put the entire body to work, from head to toe. Essentially a core and cardio exercise in one, the movement forces you to stabilize at the trunk as you jump the feet out and in. While the jumping spikes your heart rate, and your core is put to work, the upper body is also challenged with keeping you in a steady position.

Plank jacks are suitable to include in a variety of workouts, and as they require no equipment, they can be performed virtually anywhere. Read on to discover what the experts have to say about this powerful exercise.

What Are the Benefits of Plank Jacks?

Planks jacks have many health, fitness, and even postural benefits.

• Cardio: Given your heart rate will steadily rise throughout the exercise, plank jacks are exceptional for your cardiovascular health and torching fat. “In the plank position, your body is fully engaged, and adding the jacks in between will pump up your heart rate to give your muscles an even bigger challenge,” explains bande instructor Mindy Lai. 
• Strength Building: This exercise targets multiples areas to build power. “They strengthen many muscles simultaneously, including the biceps, triceps, deltoids, hamstrings, abductors, adductors, and obliques, to name a few,” outlines yoga teacher Dani Schenone.
• Core Engagement: Given the hovered position you hold during the exercise, plank jacks require all the core muscles—the rectus abdominis, transverse abdominis, internal and external obliques, and erector spinae—to activate in order to stabilize.
• Spinal Alignment: As this movement teaches you to maintain a neutral spine and control your position, it promotes optimal postural alignment.

How to Perform a Plank Jack

Below, our trainers share their tips and techniques to ensure you hit your plank jacks with proper form.

• Start in a plank position, with your shoulders over your wrists and feet hip-width apart, maintaining a straight line from your shoulders to the heels of your feet. Keep your neck elongated.
• Engage your core (and keep it engaged!) as you begin jumping your legs out laterally and then back in to the starting position, as if you’re doing a jumping jack. Try to keep your hips on the same level when moving your legs.  
• As you perform plank jacks at a quicker pace, be mindful to keep those shoulders engaged and away from the ears, and elbows softly bent to avoid hyperextending. The knees can bend throughout.
• Start with 20–30 seconds and build up your time.

Modifications

Plank jacks can be modified for lower impact if you prefer a more core-focused workout, or harder for an intensified workout. “Reduce the intensity by simply stepping it out rather than jumping, moving one leg out and in, and then alternating with the other side,” explains Lai.

You can also play with the tempo, speeding up the movement to get your sweat on, before slowing it down for a core-centric focus.

“Another modification is to perform plank jacks on the forearms to protect the wrists and elbows, and to support the longevity of your workout routine,” suggests Schenone. In general, some people prefer to hold plank on the elbows to remove pressure in the wrists and to better stabilize through the shoulders.

How Many Plank Jacks Should You Aim For?

This exercise is easy to slot into any workout, whether as part of a dynamic warm-up, a cardio drill, or a 'burnout' finisher. As with all exercise, the key is to work on optimal form first, rather than going straight for speed. For example, performing three sets of 30-second plank jumps with good form is far superior to three sets of 45-second plank jacks with poor form (which can lead to injury).

Start by practicing the movement until you master full control, and then add on a few seconds to slowly build up your rep count, while also reducing your rest time as you improve. Or, alternatively, begin with a count of 10 (jumping out and in, counting as one) with a goal to increase this count over a specific timeframe.

As there is no "one size fits all" for exercise, stick to your own exercise limits and fitness goals—whether it's increasing your cardio output or working on your core control.

Safety Considerations

Plank jacks are not suitable for anyone with joint pain as this exercise places direct weight across joints in the body. “It is so important to listen to the body during the workout to be aware of any pain, especially in the wrists, elbows, lower back, and shoulders,” advises Schenone. “Modify or choose a gentler exercise if any of these areas cause distress, and remember that progress is best when it’s slow and steady."

Make sure you hold proper form throughout and avoid any collapsing of the lower back as this can lead to unwanted pain in the region. And on the same thread, be mindful of glutes wandering up to the ceiling, You want to keep a long, straight line down the entire spine.

Finally, plank jacks are a taxing exercise, so make sure to breathe steadily throughout to avoid a drop in blood pressure and any dizziness.

The Takeaway

Plank jacks are a superlative cardio, strength, and core exercise, suitable for many workout styles. Combining jumping jacks and planks, the exercise will raise your heart rate, fire up the core, and help build strength across the body, especially the upper region. Be mindful of your form, ensuring a neutral spine and engaged core is held throughout. This exercise is not suitable for anyone who suffers joint pain, especially in the shoulders and wrists. Instead, you can try plank jacks on your elbows and moving one leg out at a time to reap the many benefits of this exercise without the high impact.

As always, it is important to consult a license physical therapist or certified personal trainer if you are experiencing joint pain during exercise to ensure proper form and use of modifications.