Thomas Test
- Target muscle
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- Equipment
- Body weight
- Body part
- Stretching
- Type
- Stretching
The Thomas Test is a clinical assessment used to evaluate hip flexor tightness and mobility. Performed at the edge of a flat surface, it reveals restrictions in the iliopsoas and rectus femoris by observing how the resting leg hangs when the opposite knee is drawn to the chest. It is commonly used by clinicians, coaches, and athletes to identify tightness that may contribute to low-back pain or altered movement patterns.
How to do the Thomas Test
- 1Sit at the very edge of a flat bench or table so that your hips are at the edge and you can safely lie back.
- 2Bring both knees toward your chest as you lower your back down onto the surface, using your hands behind your thighs for support.
- 3Once lying flat, pull one knee firmly into your chest and hold it there with both hands — keep this position throughout the test.
- 4Let the other leg lower toward the floor in a relaxed, passive manner, releasing any muscular effort in that leg.
- 5Observe or have a partner observe the position of the lowered leg: the thigh should be roughly parallel to the table and the knee should flex to approximately 90 degrees if hip flexor length is adequate.
- 6Note any deviation: if the thigh rises above horizontal, the iliopsoas is likely shortened; if the knee fails to reach 90 degrees of flexion, the rectus femoris may be restricted.
- 7Return the lowered leg to your chest, sit up carefully, and repeat the assessment on the opposite side.
Form tips
- Keep the non-tested knee pulled firmly and consistently into your chest throughout the assessment — releasing it even slightly will change the outcome.
- Relax the lowered leg completely; any active muscular effort in that limb will mask the true degree of flexibility.
- Have a partner observe or record the angle of your thigh and knee, since it is difficult to self-assess accurately from the lying position.
- Keep your lower back flat against the surface; an arched lumbar spine indicates the hip flexors are pulling the pelvis into anterior tilt and signals tightness.
- Perform the test on a surface wide and stable enough to support your entire back so you can fully relax.
Common mistakes
- Releasing the hugged knee during the test, which reduces the posterior pelvic tilt and allows the lowered leg to drop farther than it truly can — leading to a false negative result.
- Allowing the lower back to arch off the surface, which tilts the pelvis anteriorly and compensates for tight hip flexors, masking the restriction.
- Actively lowering the hanging leg by muscular effort rather than letting gravity do the work, which produces an inaccurate reading of passive flexibility.
- Performing the test on a surface that is too soft or too narrow, causing the body to shift or tense up and preventing a relaxed, neutral position.
- Judging the result by feel alone without visual observation, since the difference between adequate and restricted range can be subtle and easy to misjudge without a second set of eyes or a video.
Frequently asked questions
What does the Thomas Test assess?
It assesses passive hip flexor flexibility, primarily identifying tightness in the iliopsoas and the rectus femoris. The angle of the thigh and degree of knee bend on the hanging leg indicate whether either structure is shortened.
What is a normal result on the Thomas Test?
A negative (normal) result is when the thigh of the lowered leg lies flat or slightly below horizontal and the knee flexes to roughly 90 degrees. If the thigh rises above horizontal or the knee cannot reach 90 degrees, some degree of hip flexor restriction is present.
Can I use the Thomas Test to stretch my hip flexors, not just assess them?
The position does place the hip flexors in a lengthened state, so holding the lowered-leg position for 20–30 seconds can serve as a passive stretch. However, its primary role is assessment, and dedicated hip flexor stretches performed consistently will be more effective for improving flexibility over time.
Do I need any equipment to perform the Thomas Test?
No equipment beyond a firm, flat surface such as a bench, plinth, or table is required. The test relies entirely on body weight and gravity to reveal hip flexor range of motion.
How often should I test my hip flexor flexibility with the Thomas Test?
Testing every four to eight weeks gives enough time for meaningful changes in flexibility to occur. Use it as a baseline before starting a stretching program and then retest periodically to track progress.
