I love exercises that can be a core exercise, an activation exercise, a mobility exercise and a flexibility exercise. Exercises that check 4 boxes have massive value. The Sandbag Leg Lower is a version of the FMS Leg Lowering exercise utilizing the Ultimate Sandbag as a counterbalance. The sand bag "turns on" or engages the anterior core muscles by supplying an extension force. The core muscles must produce an anti-extension force or, a flexion moment. This acts as a stabilizing force and increases both the efficacy and complexity of the leg lower. Great as a pre-workout warm-up.