The zombie sit-up isn’t for the faint of heart; to find out more, I added it to my workouts for a week and felt the difference in my abs.

More from Tom's Guide Forget sit-ups — build a stronger core and boost your balance with this 25-minute standing abs workout Build a stronger core with this 10-minute standing abs workout ...

The fitness test, given to school children, began in 1956 but was phased out in 2013 during the Obama administration.

Sit-ups are a simple bodyweight exercise. Here's how to perform sit-ups safely, according to experts, and the muscles worked, along with the benefits.