Based on the results of this study, we can identify exercises that produce the highest amount of EMG activity.
Side-lying hip abduction – 81%
Single limb squat – 64%
Lateral band walk – 61%
Single-limb deadlift – 58%
Single-limb squat – 59%
Single-limb deadlift – 59%
Sideways, front, and transverse lunges – 41-49%
In addition to the manuscript, there are good video demonstrations of the exercises and a PowerPoint presentation available at the JOSPT website. When I accessed this, I believe they were all available for free.
Based on the results of this article, here are a few things that came to my mind
Side-lying hip abduction should be used in all people needing glut medius strengthening. EMG activity was almost 20% higher than the next exercise.
The single limb squat and single-limb deadlift exercises activated high amounts of EMG activity for both muscles
The clam exercises produced EMG activity between 34-40% for both muscles. While this is low in comparison to other exercises, the authors did not use resistance during testing. I would still use this, especially with a resistance band around the thighs, as am early-stage or activation exercise. The authors also compared clams at 30 degrees and 60 degrees of knee flexion and showed no different in gluteus medius activity.
The lunge exercises produce a moderate amount of EMG activity and are likely good early-stage exercises to progress to prior to the single-leg squat and deadlift exercises
DiStefano, L. (2009). Gluteal Muscle Activation During Common Therapeutic Exercises Journal of Orthopaedic and Sports Physical Therapy DOI:10.2519/jospt.2009.2796