What is the primary focus of high knees as an exercise?

High knees primarily target cardiovascular endurance by engaging multiple muscle groups while elevating the heart rate. This exercise requires an individual to rapidly alternate lifting their knees towards their chest, which not only works the legs but also increases overall aerobic capacity.

While performing high knees, the quick and repetitive movement boosts the cardiovascular system, promoting better heart health and improving stamina. The intensity of the exercise, combined with the elevated heart rate, makes it an effective cardiovascular workout.

Although high knees do involve the core for stabilization and can enhance lower body strength, those aspects are secondary to the main goal of improving cardiovascular fitness. Other choices, such as upper body strength or lower body flexibility, are not the primary focus of high knees, solidifying why enhancing cardiovascular endurance is the correct answer.