Aqua ABCs: Abs, Back, Core With Sandy Stoub, MA Develop core strength, endurance, muscle balance, and flexibility through dynamic and static movements emphasizing abdominals and back. To access this content, you must purchase Aqua ABCs: Abs, Back, Core, OnDemand Monthly Subscription Payment Plan, OnDemand Annual Subscription, OnDemand Monthly Subscription, OnDemand 6-Month Subscription or OnDemand 2 Year Subscription or log in if you are a member.