Plank on a Medicine Ball Place your medicine ball on the floor ... which not only slashed my time at the gym in half, but also left me drenched. I also woke up with sore inner thighs, butt ...

This ab workout includes core-strengthening exercises like half sit-ups and side ... Tip: Hold a dumbbell or medicine ball for extra intensity. 4. Side plank with dips Place one elbow directly ...