Isometric, isotonic, and isokinetic exercises refer to the different techniques for activating and strengthening muscles. Isometric exercises, like planks, involve activating muscles with no movement.

The effects of a repetition push-up exercise programme and a repetition combination isometric-isotonic push-up exercise programme upon muscular endurance as measured by maximum repetition of push-ups ...

When it comes to the gym, isometric exercises probably aren't the first movements that come to mind. But with 4.4k of you ...