Final answer:
The Weight vest 1 leg squat is the variation of the 1 Leg Squat that adds additional resistance to increase intensity and difficulty, challenging the quadriceps, hamstrings, glutes, and core muscles more intensely.
Step-by-step explanation:
The exercise that is a variation of the 1 Leg Squat is B) Weight vest 1 leg squat. This variation adds additional resistance in the form of a weighted vest, which increases the intensity and difficulty of the exercise. While other options like the 1 leg squat with a tennis ball, the offloaded 1 leg squat, or the 1 leg squat to a high box are also variations, they emphasize different aspects such as balance, load distribution, or range of movement.
The weight vest 1 leg squat targets the same muscle groups as the traditional 1 leg squat, primarily the quadriceps, hamstrings, glutes, and core. By adding the weight vest, you also engage the stabilizing muscles of the core and lower body more intensely to maintain balance and posture throughout the exercise. Incorporating this variation into a fitness routine can offer a greater challenge and provide a progression for individuals looking to advance their single-leg strength and balance.