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.

Isometric exercises like wall sits, planks, and glute bridges hold the body in one position for a set period of time. Muscles are contracted and engaged, but they don’t lengthen during the exercise.

Abs, schmabs. Despite the standing reputation as the hallmark of fitness, a toned belly doesn't really mean much (just that your body fat percentage is low enough to show your abdominal muscles).