Sorensen Core Strength Test: Protocol and Reference Tables

The Sorensen test (Sorensen back extension test) is one of the reference tests for assessing the endurance of the lower back extensor muscles, a key area for preventing low back pain. It's an isometric, simple test, widely used in research and physiotherapy assessments.

What does this test measure?

It measures the maximum time a person can hold the upper body horizontal, with the lower body fixed on a table or bench, before the position breaks down due to fatigue. It assesses the isometric endurance of the lower back extensor muscles (erector spinae, multifidus), a muscle group key to lumbar stability.

Equipment needed

• A table or bench that allows the upper body to extend off the edge
• Straps or a partner to secure the pelvis and legs
• Stopwatch

Step-by-step protocol

1. The person lies prone on the table, with the anterior superior iliac spine right at the edge, so the upper body hangs off the table
2. The pelvis, hips, and legs are secured with straps or held by a partner
3. The person crosses their arms over their chest (or as specified by the protocol) and lifts the trunk until horizontal, in line with the legs
4. Start the stopwatch as soon as the horizontal position is reached
5. Stop the stopwatch when the trunk drops below horizontal in a sustained way
6. Record the time in seconds

Common mistakes

• Not securing the pelvis and legs properly, allowing compensations that artificially extend the time
• Allowing the person to lift the trunk above horizontal at the start (hyperextension), which is not part of the standard protocol
• Stopping the test subjectively without a clear criterion for "loss of the horizontal position"

How to interpret the results

Level	Men (seconds)	Women (seconds)
Low	< 60	< 50
Acceptable	60-120	50-100
Good	120-180	100-150
Very good	> 180	> 150

These values are a general guide for adults without active low back pathology. In people with current or recent low back pain, the test should be applied with caution and under the guidance of a physiotherapist, as it may not be appropriate during acute phases.

How this test relates to others

The Sorensen test pairs with other core tests for a complete picture of trunk musculature:

• Plank Test — assesses the anterior core muscles, contrasting with the posterior chain
• Side Plank Lumbopelvic Control Test — adds the lateral component to the assessment

Track your progress

In low back pain prevention or rehab programs, back extensor endurance is a key marker worth tracking over time. With Movalytics you can record the time from each assessment along with any relevant observations (pain, compensations), comparing how lumbar endurance progresses throughout the process.

FAQ

Is it safe to do this test with low back pain? In acute phases of low back pain, this test may not be appropriate. It should always be assessed within a process supervised by a physiotherapist. What's its relationship to low back pain risk? Low endurance of the back extensor muscles has been linked to higher low back pain risk in some studies, although the relationship isn't strictly causal and doesn't apply equally to everyone. How often should it be repeated? Every 6-8 weeks is usually reasonable within a low back prevention or rehab program, to assess progression in muscular endurance.