Yes, this is super weird. But it nails the transverse abdominis (the deep core muscle that's like a natural weight belt) and even the internal obliques.
The transverse abdominis is a deep core muscle that acts as a natural weight belt for your spine. It's the Spanx of your abs. Developing it will help prevent injuries and create a smaller waist. You could train it with plank variations, but I like this exercise using an ab wheel and a treadmill.
Hold the ab wheel the same way you would for a rollout, but instead of rolling out, you hold it like a plank. This will also hit the internal obliques. It's fun and quite possibly a better use of the treadmill than jogging for abs. The slower the treadmill goes, the harder it is.
Stretching... it doesn't decrease soreness, prevent injury, or even improve your performance. The truth has been stretched too far for too long. Let's put it in its place.
Most lifters use just a handful of exercises to build their glutes and hamstrings. While the basics are still the best, here are some cool variations to provide some much needed posterior chain variety.