This clam shell exercise move is not only great for building strength in the hip abductors, but it also works perfectly for hip, leg, and lower back rehabilitation. Physical therapists commonly use clam shells and other hip abduction exercises to help patients recover due to their effectiveness in strengthening the glutes and easing lower back injuries.
Sidorkewicz, N, et al. (2014). Examining the effects of altering hip orientation on gluteus medius and tensor fascae latae interplay during common non-weight-bearing hip rehabilitation exercises. Clinical Biomechanics.