Isometric exercises are moves where you hold in a position under tension… and while planks are great isometric core exercises, they aren’t your only option.
These MUST-DO isometric core exercises are a great way to build your core stability and strength so that your core works properly all the time.
It’s true you can train your core in just 7-minutes and although you’re contracting your muscles you’re not actually moving.
Coach Chris Wilson
Head Strength Coach – CriticalBench.com