It challenges every muscle group and boosts your pulse rate, a strong indicator of difficulty.
It will burn practically every leg and glute muscle, requiring calories to rebuild them.
While trying to burn calories, more muscle groups are preferable.
It requires explosive surges of energy that stimulate the quadriceps, hamstrings, and glutes significantly.
Holding your legs in the air necessitates an isometric hold that can challenge even the strongest individuals.
It stimulates your pectoral muscles, which are among the largest muscle groups in your body.
It engages the butt, quadriceps, and hamstrings while elevating the heart rate.
It activates one of the greatest muscle groups in the body, the back muscles.
It engages the entire core and necessitates a ferocious effort, meeting the criteria for "challenging."