Thomas Test: How to Assess Hip Flexor Tightness

If you work with clients who spend long hours sitting (which is basically everyone) or athletes dealing with lower back or anterior hip discomfort, the Thomas Test should be one of the first things you add to your assessment. It's quick, requires no equipment, and gives you direct insight into the state of the hip flexors — one of the muscle groups that tightens up the most with a sedentary lifestyle.

It also has the advantage that a single position lets you assess several muscles at once, simply by paying attention to where the limitation shows up.

What does this test measure?

The Thomas Test assesses tightness or excessive tension in the hip flexors, mainly:

• Iliopsoas: if the leg being tested can't rest on the table and stays "floating" in hip flexion
• Rectus femoris (a two-joint quad muscle): if that same leg's knee can't maintain its flexion and the shin tends to extend
• Tensor fasciae latae / IT band: if the leg drifts outward (abduction) during the test

A good result on the Thomas Test tells you the pelvis can stay in a neutral position without these muscles "pulling" it into anterior tilt — something highly relevant for movements like squats or lunges.

Equipment needed

• A table or bench sturdy enough and with enough space for a leg to hang off the edge
• Optional: a goniometer, to quantify the hip and knee extension angle

Step-by-step protocol

1. The person sits at the edge of the table and lies back into a supine position, pulling both knees to their chest with their hands
2. They hold one leg against their chest (full hip and knee flexion) to fix the pelvis and remove excessive lumbar lordosis
3. The other leg is allowed to drop freely off the edge of the table, with no active assistance
4. Observe three things on the hanging leg:

- Does the thigh reach or get close to parallel with the table? (hip extension) - Does the knee maintain roughly 80-90° of flexion? (rectus femoris) - Does the leg stay aligned, or does it drift outward? (tensor fasciae latae / IT band)

1. Repeat on the other side and compare

Common mistakes

• Not properly fixing the pelvis with the opposite leg held to the chest, which skews the result through lumbar compensation
• Confusing limited hip extension (psoas) with limited knee flexion (rectus femoris) — these are distinct findings with different implications
• Letting the person actively "push" the leg down instead of letting it drop under gravity

How to interpret the results

Finding on the hanging leg	Interpretation
Thigh parallel to/touching the table, knee at ~90°, no lateral drift	Negative — good hip flexor length
Thigh elevated above the table (doesn't reach horizontal)	Positive — iliopsoas tightness
Knee extends beyond 90° (shin "rises")	Positive — rectus femoris tightness
Leg drifts into abduction	Positive — tensor fasciae latae / IT band tightness

It's common to find combinations (for example, tight psoas plus tight rectus femoris), especially in people who sit for long hours or runners with quad dominance.

Related tests

The Thomas Test is often paired with other hip and lumbopelvic tests:

• Ober Test — completes the assessment of the IT band and tensor fasciae latae from a different position
• FABER Test — adds information about hip external rotation and abduction mobility

Track and follow up

Hip flexor tightness doesn't resolve in a single session: it requires ongoing mobility work and, above all, objective tracking to see whether it's improving. In Movalytics you can log the Thomas Test result for each side separately (psoas, rectus femoris, TFL), compare it with previous assessments, and visually see whether your mobility programming is paying off.

Frequently asked questions

Does the Thomas Test hurt? It shouldn't. If sharp pain appears in the groin or hip when the leg drops, stop the test and assess for a possible joint issue before continuing. How often does it make sense to repeat this test? For clients working specifically on hip mobility, repeating it every 4-6 weeks is usually enough to see objective changes. Does a positive result always mean stretching is the answer? Not necessarily. Apparent tightness can also stem from a lack of motor control or a pelvis compensating in another way. It's worth combining this test with others (like the FABER) before deciding on an approach.