Final answer:
The band in the reverse goblet lunge is used to promote knee stability by providing resistance against valgus forces, requiring the stabilizing muscles around the knee to engage more actively.
Step-by-step explanation:
For the reverse goblet lunge with a band, the purpose of the band attempting to pull the knee of the working leg into valgus is to Promote Knee Stability. During this exercise, the band's pull creates resistance that the muscles have to work against to maintain the proper alignment of the knee. This helps reinforce the stabilizing muscles around the knee, including the gluteal group, which when engaged, assists with raising the knee at the hip and maintaining posture by stabilizing the iliotibial tract (IT band) that connects to the knee. The reference to the piriformis, obturator internus and externus, superior gemellus, inferior gemellus, and quadratus femoris muscles underscores their role in lateral rotation of the femur, which is complemented by the exercise's focus on knee stability and the dynamic control required during the lunge movement.