Look at that nice, straight back!  During this kettlebell swing, Julie has her knees back and over her toes, her chest up and her back straight.  This is great form for any movement..whether it be an air squat, a deadlift, or picking up a piece of furniture.  This form encourages the use of glutes and hamstrings, and minimizes stress on the lower back.

100 Russian KBS

5 laps around track

100 air squats