Trendelenburg Test: how to detect gluteus medius weakness

If you've ever watched someone run and noticed their hip "drop" to one side with each stride, you're probably seeing in motion what the Trendelenburg test picks up in a static position: a weakness or inhibition of the gluteus medius that isn't doing its job of stabilizing the pelvis.

It's one of the most commonly used tests in hip, knee, and running assessments precisely because it connects directly to very common injuries (patellofemoral pain, iliotibial band syndrome, low back pain).

What does this test measure?

The Trendelenburg test assesses the ability of the gluteus medius (and, to a lesser extent, the gluteus minimus) to stabilize the pelvis in the frontal plane during single-leg stance.

When the gluteus medius on the standing side is working properly, it keeps the pelvis roughly level. If it's weak or not activating well, the pelvis on the lifted side drops (a positive Trendelenburg sign).

Equipment needed

• None. You just need enough space for the person to stand and lift one leg
• Optional: a wall or surface nearby for support, in case of balance issues

Protocol

1. The person stands barefoot, facing you (or with their back to you, depending on which view you prefer)
2. Ask them to bend one knee and lift that foot off the floor, balancing on the other leg for about 6-10 seconds
3. Watch the relative height of both iliac crests or posterior superior iliac spines (PSIS)
4. Repeat with the other leg and compare both sides
5. Optionally, repeat the test with eyes closed to add a proprioceptive challenge (more demanding)

Common mistakes

• Letting the person lean their trunk sideways to "compensate" for the pelvic drop (this can mask a true Trendelenburg sign — known as a "compensated Trendelenburg")
• Observing from only one angle: ideally you should view from behind, at the level of the iliac crests
• Not telling the person to stay upright without using compensation tricks

How to interpret the result

Result	Interpretation
Pelvis stays level (or rises slightly on the standing side)	Negative — good gluteus medius function on the standing side
Pelvis on the lifted side drops	Positive — suggests weakness or inhibition of the gluteus medius on the standing side
Trunk leans toward the standing side to compensate	Compensated Trendelenburg — also indicates glute dysfunction, even if the pelvis doesn't visibly drop

It's important to remember that the "responsible" side is always the standing side, not the side where the pelvis visibly drops. This is a very common interpretation mistake.

Related tests

The Trendelenburg test pairs well with:

• FABER (Patrick) Test — if there's anterior hip pain in addition to glute weakness, it's worth also ruling out intra-articular involvement
• Hip Adductor Squeeze Test — to get a fuller picture of hip chain strength (abductors vs. adductors)

Track and record it

Gluteus medius weakness is one of those findings that improves with targeted training (side planks, monster walks, single-leg work), but only if you actually track progress. In Movalytics you can record the Trendelenburg result (positive/negative, affected side, with or without trunk compensation) at each assessment, and check whether the glute strengthening program is paying off within a few weeks.

Frequently asked questions

Is the Trendelenburg test only useful for runners? No, although it's very popular in running assessments. Gluteus medius pelvic stability matters for any single-leg activity: climbing stairs, walking, single-leg squats, change-of-direction sports, and more. Does a positive Trendelenburg mean there's an injury? Not necessarily an injury, but it does indicate a motor control or strength deficit that can be a risk factor for knee, hip, or low back injuries — and therefore deserves attention. Can the weakness detected by the Trendelenburg test be improved? Yes, in most cases it responds well to a targeted gluteus medius strengthening program and single-leg motor control work, with visible improvements after a few weeks of consistent training.