Dead Bug

Starting position

1. Lie in a supine position on a mat.
2. Bend your legs slightly at the knees or leave them straight.  
3. Keep your arms straight and facing forward.

Implementation

1. In a slow and controlled motion, lower the opposite limbs to the floor, constantly maintaining tension in the abdominal muscles.
2. Hold the limbs in the lower position for about a second, then with a decisive movement return to the starting position.
3. Repeat the exercise a set number of times.