Get full access to Outside Learn, our online education hub featuring in-depth yoga, fitness, & nutrition courses, when you
sign up for Outside+.

Yoga practitioners have long known the power of Plank Pose. Now the military is catching up. The Navy Physical Readiness Test (PRT) that service members have to pass now includes a one-minute forearm plank instead of a two-minute sit-up test.

The PRT is a means of assessing the general fitness of Navy recruits, reservists, and other sailors. The goal is to ensure that they maintain physical and mental stamina and the strength they need to perform their shipboard and other military duties. The test “evaluates aerobic capacity, or cardio-respiratory endurance, muscular strength, and muscular endurance,” according to Navy guidelines.

Plank vs. sit-up

Earlier this year, the Naval Health Research Center (NHRC) determined that forearm plank is a better test of core strength and abdominal muscle endurance. According to a memo published by the Navy Administration, the repeated spinal flexion movement of the “curl-up” (also known as a “sit-up”) is not “operationally relevant, may aggravate lower-back injuries, and does not appropriately challenge the abdominal musculature.”

Sit-ups compress and flex the lumbar spine, which can put pressure on the lower back. Additionally, sit-ups can cause tight muscles in the hip flexors, which can also transfer strain to the back muscles. On the other hand, plank poses (including forearm plank) stabilize the core muscles, which in turn stabilize your entire body during movement. The pose also strengthens your shoulder and gluteal muscles. Working in concert, these muscles help improve your posture, which can help keep you active and avoid injury.

Fundamentals of forearm plank

The official memo for the Navy PRT describes forearm plank as a functional exercise—the kind that prepares your body for daily activities. The shipboard tasks that require pulling, pushing, lifting, or carrying use significant core strength. You also need strength in the arms, shoulders, pelvic floor and even the back muscles–all of which are activated when you hold a plank.

Forearm plank is an isometric core exercise which uses your body weight to counter the force of gravity. In this pose, you hold your trunk and legs in a straight line off the ground supported by your toes and forearms. In this position, gravity causes a downward force on your trunk, but your core muscles work to create an upward force that counteracts it. The more strength you have in your core, the less likely your trunk will sag or collapse to the ground.

Per Navy Planking Standards, plank activates the ab and trunk muscles in a way that mimics the main function of the abdominal musculature: to stabilize your spine. With stronger core muscles supporting your trunk, your spine can move freely without injury while you perform your daily activities.

Plank pose for  posture

“I spend a lot of time hunching over to reach the controls in my helicopter,” says Lieutenant Commander Erin Edwards, a Navy helicopter pilot, flight instructor, and yoga practitioner. “[This posture], combined with the vibrations of the aircraft and the weight of my gear, induces tons of stress onto my lower back.”

Consequently, Edwards designs her fitness regimen to ensure her health and safety for her duties as a pilot. “The best way to help combat the strain on my body while I’m flying is by maintaining a strong core. Yoga has been my greatest remedy,” she says.

Edwards calls the previous Navy PRT “a sit-up race against the clock.” She says that in order to move fast enough to get a perfect score of 100 sit-ups within 2 minutes, sailors tended to employ their hip flexors and other muscles.

She says she’s grateful for the PRT’s transition to forearm plank because she feels it is more core focused. As a yoga practitioner, Edwards found the switch to this strength test an easy transition. Edwards hopes that it encourage more sailors to take up yoga for its benefits of flexibility, strength, and focus.

Let Lieutenant Commander Erin Edwards guide you through a sequence that will help you build up to Forearm Plank Pose. This Core Sequence Will Help You Nail the Navy’s Strength Test—Really.


About our contributor

Ingrid Yang is an internal medicine physician, yoga therapist, and author of Adaptive Yoga and Hatha Yoga Asanas. Dr. Yang has been teaching yoga for more than 20 years and leads trainings and retreats all over the world, with a special focus on kinesthetic physiology and healing through breathwork, meditation and mind-body connection. Find out more at or on Instagram.