Resistance band decelerating side lunges strengthen the hamstrings, core, and glutes. This exercise will target the glutes much more than forward or reverse lunges. They are also easier on the joints than forward or reverse lunges. This exercise is great for hip mobility and injury prevention. Learn more about properly executing this exercise with the video above.
Regression
To make the movement easier, have your client move closer to their anchor to reduce tension on the Slastix. You can also reduce tension by using a lighter resistance of Slastic.
Progression
Increase the intensity by having your client move farther away from their anchor, placing more tension on the Slastix, or stack Slastix for more tension.