Russian Twists and Medicine Ball decline crunch

A quick visit to the gym this morning (an anomaly for Saturday) but got in 20 minutes of running and some core work.

Here's part of what I did:

Russian Twist: 

1. Sit on a mat and hold feet out in front, but elevated slightly off the ground (balancing on the butt)
2. Hold a medicine ball in front, and rotate shoulders to the left. hold the position for a breath then rotate to the right- hold again. (keeping feet elevated)
3. 3 sets of 30 reps - 15 per side 

Medicine ball decline crunch: 

1. Lie on a decline bench and secure legs in the end
2. Hold a medicine ball at chest
3. Push the small of back down against the bench so to isolate abdominal muscles
4. Contract abs and lift shoulders off of the bench, while simultaneously pushing the medicine ball towards the ceiling
5. Hold the position, then inhale and lower shoulders down at a controlled speed.
6. 3 sets of 30 reps.