Final answer:
Levar is performing mountain climbers, a variation of the plank exercise that includes lifting each knee to the chest, providing an intense workout for the core, shoulders, and legs.
Step-by-step explanation:
While holding a plank position, Levar alternates lifting each knee to his chest, which is most likely a variation of the plank exercise known as the mountain climbers. This exercise is an intense cardiovascular workout that also targets several muscle groups including the core, shoulders, and legs. By adding the knee-to-chest movement, Levar is increasing the intensity of the traditional plank and incorporating a dynamic motion that engages additional muscles, leading to a more comprehensive workout.