Stabilization is the first phase of core training. Videos 1️⃣ and 2️⃣ are core stabilization exercises and will the legs may move, notice the spine does not. Note: the Swiss Ball makes this an advance exercise but may be done on a bench instead. Core strength exercises require movement of the spine through small- large ranges of motion and integrate the full muscle-action (eccentric, isometric and concentric). Videos 3️⃣ and 4️⃣ show core strength moves.