Plank Change to PFT Article by Human Performance Office, Aug 4, 2021
For decades, the Marine Corps has used crunches to both improve and assess abdominal endurance. However, research has shown that crunches with the feet restrained require significant hip flexor activation. This has been linked to an increased risk of injury, including lower back pain due to increased lumbar lordosis.
The plank presents numerous advantages as an abdominal exercise. The plank’s isometric hold requires constant muscle activation, activates almost twice as many muscles as the crunch, and has been proven to be most reliable in measuring the true endurance required for daily activity function. With increased core strength, Marines are less likely to experience injury or fatigue during functional tasks like hiking, lifting and low crawling.
In 2020, the Marine Corps adopted the plank as an alternative to crunches for the annual Physical Fitness Test (PFT) as a means to measure core stability, strength, and endurance while reducing risk of injury. For PFTs conducted in 2022, Marines will still have the option to conduct the plank or the crunch just as in 2021, with slight scoring adjustments - the new time for the maximum score will 3:45, reduced from 4:20. The time for the minimum score has also been adjusted, increasing from 1:03 to 1:10. Finally, the plank will be mandatory in 2023, replacing the crunches as an authorized PFT exercise.
For more information and resources, including a four-week core strength training plan, see below or visit https://usmcfitforce.com and reference MARADMIN 404/21 at https://www.marines.mil/News/Messages/Messages-Display/Article/2719680/forthcoming-changes-to-the-physical-fitness-test/.