How to do: Janda Sit-Up

Step-by-step instructions

1. 1Position your body on the floor in the basic sit-up position; knees to a ninety degree angle with feet flat on the floor and arms either crossed over your chest or to the sides. This will be your starting position.
2. 2As you strongly tighten your glutes and hamstrings, fill your lungs with air and in a slow (three to six second count) ascent, slowly exhale. Tip: It is important to tighten the glutes and hamstrings as this will cause the hip flexors to be inactivated in a process called reciprocal inhibition, which basically means that opposite muscles to the contracted ones will relax.
3. 3As you inhale, slowly go back in a controlled manner to the starting position.
4. 4Repeat for the recommended amount of repetitions.

Photos & base instructions from the open-source Free Exercise DB (public domain).