Introduction to the Muscle KO Series
The purpose of this series is to provide readers with an understanding of how stabilizing groups of muscles work. The more a client knows about how muscles work, the more they can learn from their trainers. This series aims to provide some of that fundamental knowledge.
During the final block of medical anatomy, my classmates and I learned the muscles of the arms and legs. It quickly became difficult to remember exactly what muscle did what and in the company of which other muscles. I found the most effective way to learn how muscles work is to learn about disorders that target specific muscle groups and see what symptoms present in patients.
This article focuses on the insanely interesting (to me) gluteus medius and gluteus minimus, which are knocked out in the Trendelenburg gait. Trendelenburg gait is an irregular walking pattern in which the hips sway excessively side to side due to lack of hip stability.
Abduction: raising the leg to the side, away from the midline
Internal Rotation: twisting the thigh so the kneecap points towards the midline
Gluteus Medius and Gluteus Minimus at Prevail
Many at Prevail Conditioning train their gluteus medius and gluteus minimus whether they know it or not. They are primary stabilizers for walking and all single leg exercises. Many warm-ups include banded movements, like clamshells, that target the gluteus medius and gluteus maximus. Lateral band walks and single leg banded hip extension with external rotations also target the abduction and stabilizing roles of the gluteus medius and gluteus minimus.
The gluteus medius and gluteus minimus lie deep to the gluteus maximus. Their function is to abduct and internally rotate the thigh. The gluteus medius is particularly important because it is the strongest abductor of the hip muscles. Both muscles begin at the outside of the hip and descend to the lateral, posterior side of the femur (see figure).
In life, the gluteus medius and gluteus minimus contract together whenever a step is taken. When one leg lifts to take a step, both muscles contract to keep the body balanced on the planted foot. Similarly, when one balances on one foot, the gluteus medius and gluteus minimus contract to keep the hip level.
Trendelenburg gait occurs when the gluteus medius and gluteus minimus are weakened, meaning abduction at the hip will be weakened. Now when a step is taken, the weight of the raised leg causes that hip to drop. The body then loses stability and leans towards the raised leg. To keep from falling, the lumbar spine bends towards the planted leg (see figure and video).
In the video above, we can see that whenever the patient plants with her left foot, her left hip lurches outward, showing a weakness in the gluteus medius and gluteus minimus. This is a common pattern in runners where it can lead to knee and lower back injuries as the hip tilts from side to side every step (Davis et al, 2016).
The gluteus medius and gluteus minimus are essential to every step we take. They are the primary hip abductors and critical to athletes’ stability in all single leg exercises.
Washington University Musculoskeletal Atlas
Stanford Medicine 25
Davis IS, Futrell E. Gait Retraining: Altering the Fingerprint of Gait. Physical medicine and rehabilitation clinics of North America. 2016;27(1):339-355. doi:10.1016/j.pmr.2015.09.002.
Souza RB. An Evidence-Based Videotaped Running Biomechanics Analysis. Physical medicine and rehabilitation clinics of North America. 2016;27(1):217-236. doi:10.1016/j.pmr.2015.08.006.
University of Pittsburgh School of Medicine Anatomy Course
B.S. – Cellular Molecular Biology (Westmont)
M.D. Candidate – University of Pittsburgh School of Medicine
Tyler was born and raised in Santa Barbara, California and began training at Prevail in October 2016. While at Westmont he graduated summa cum laude, led a student-run homeless outreach program, and volunteered with Hospice of Santa Barbara.
After Tyler’s mother was diagnosed with rheumatoid arthritis (RA), he became interested in the cellular mechanisms behind the disease. He conducted his Major Honors project at Westmont on the role of the microbiome in inflammatory arthritis and conducted summers of research at Harvard Medical School studying the role of macrophages in RA. His research has resulted in seven presentations, three at national medical conferences.