Planks will soon be mandatory for Marine Corps physical fitness test ― completely replacing timed crunches.
The change will take place in 2023, according to a MARADMIN released Thursday.
“For decades, the Marine Corps has used sit-ups and crunches to both improve and assess abdominal endurance,” Capt. Samuel Stephenson, a spokesman for Marine Corps Training and Education Command, said in an email. “However, research has shown that sit-ups and 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.”
Though the Marine Corps knew crunches were more of an injury risk, the service branch has not conducted any studies to find out exactly how big the problem is.
“There is no current research showing long term effects of the plank versus crunches, although we do know that the crunches place stress on the spinal column, neck, and cervical spine due to the repetitive loading and increased use of hip flexors,” Maj. Lindsey Slyman, the programs and assessments section head, Human Performance Branch, Policy and Standards Division, Training and Education Command, told Marine Corps Times in an email.
In addition to reducing injuries the Corps sees the plank as a better measure of core strength and endurance than crunches.
“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,” Stephenson said in the email.
Since the plank was made an option in 2019, very few Marines have chosen to perform one over the timed crunches.
In 2020 only 3 percent of the Marine Corps chose the plank prior to the PFT season being cut short by the COVID-19 pandemic.
In 2021 only 6.9 percent of Marines opted to perform the plank over the traditional crunches.
In addition to making the plank mandatory in 2023, the Corps will make adjustments to plank scoring, which will go into effect in 2022.
When the plank was introduced Marines were required to hold the plank position for one minute and three second to hit the minimum score and four minutes and 20 seconds to achieve the max score.
Of the 6.9 percent of Marines who opted to perform the plank in 2021, 69.4 percent managed to max out the score while no Marines failed the event, Stephenson told Marine Corps Times.
Using that data the Corps has lowered the max score and raised the minimum score.
To receive max points for the plank portion of the PFT Marines will now have to hold the position for only 3 minutes and 45 seconds, according to the MARADMIN.
The minimum time to pass the event is now one minute and 10 seconds, according to the MARADMIN.
In 2021 74.5 percent of Marines achieved the new max time, while 0.1 percent of Marines would have failed the updated minimum time, Stephenson said.
As more Marines perform the plank in the coming years, the Corps will monitor results and adjust the scores accordingly.
“All human performance policies and standards are in a constant state of analysis, assessment, and modification if necessary,” Brian McGuire, the human performance branch head, Policy and Standards Division, Training and Education Command, told Marine Corps Times in an email.
In conjunction with the release of the MARADMIN the Corps will release a brief training plan to help Marines in the fleet improve plank times.
“The plank is a foundational movement and is already worked into fitness programming that Force Fitness Instructors, Recruiters, OSOs and Entry Level Training schools utilize, thus no large changes are planned,” Slyman said.
“But, as a part of this announcement, Human Performance Branch is releasing a four-week training program to provide individuals tools to train specifically for the plank portion of the physical fitness test.”