Planks With Alternating Leg Lifts
Not only are they a great ab exercise, but planks are also perfect for training your core effectively. By lifting your legs you will also target your glutes, hamstrings, and hips, especially if you do them after a lower body session. Try doing them for 30-45 seconds at a time and increase the time from there.
Tip: Make sure to tuck in your stomach and try to envision your belly button connected with your spine.
[Photo via]