TRX Knee Tucks
If you have access to a TRX, try this exercise — it's intense.
- With the straps at mid-calf length, place your feet into each of the foot cradles.
- Lift your knees off the ground, coming into a plank position with your hands directly underneath your shoulders. Your back should be flat and your core should be engaged (there should be no arch or dip of the torso visible).
- Bring both knees in toward your elbows at the same time. Extend your legs, returning to your starting position. This completes one rep.