Planks are boring, and this is sort of a plank, but it's a doozy! Not only does it force you to resist extension (a missing element in most core training), but it also trains the core by developing stability through the contralateral shoulder and hip. There's a transference of force between contralateral sides and training the core in this fashion helps tremendously.
Contralateral Core Lift
- Place the left palm inside the left inner thigh.
- Tuck the chin and lift the head slightly.
- Push through the right elbow and left knee. Be sure NOT to allow your lower back to go into extension.
- Hold the raised position for 5 seconds. Repeat once more, and then switch sides. That's one set.
This is tougher than it looks and there's a certain level of strength required, but for those who can do it correctly, it's awesome.