In a single leg squat, what should the knee's position be?

In a single leg squat, having the knee slightly flexed but not locked is essential for maintaining proper stability and functionality during the movement. This slight flexion allows for optimal tracking of the knee over the foot, enabling better alignment and reducing the risk of injury, particularly to the knee joint and surrounding structures.

This position also allows for better engagement of the muscles around the knee and hips, promoting strength development and balance. Locking the knee would restrict movement and could lead to joint strain or injury, while fully extending the knee may reduce the effectiveness of the exercise, as it does not allow the necessary engagement of stabilizing muscles. A 90-degree angle approach is excessive and not typical for a single leg squat, as the goal is to maintain a controlled, yet dynamic movement through a range that encourages strength without compromising stability.