Low back pain is unusual among sporting injuries in that it rarely announces a clear moment of “reinjury” the way a hamstring or ankle does. Instead it tends to creep back in, a bit stiffer this week, a bit more guarded the next, until an athlete is training below their capacity without anyone quite deciding they should be. The Biering-Sørensen test is one of the few simple, well-validated tools for putting a number on trunk extensor endurance before that pattern sets in.
WHAT THE TEST ACTUALLY MEASURES
The test is performed lying face down with the pelvis and legs fixed on a table, the upper body unsupported and held horizontal, in line with the legs. The time the position can be held before form breaks down is recorded. It’s a direct measure of isometric endurance in the back extensors, the muscles that keep the trunk upright and controlled during running, lifting, and repeated bending and twisting under fatigue.
The test was first described by Biering-Sørensen in a 1984 study published in Spine, which followed working adults for a year and found that a shorter holding time was a significant predictor of who would go on to develop low back trouble. A 1999 study by Latimer and colleagues, published in the same journal, confirmed the test’s reliability and its ability to discriminate between people with and without low back pain, reporting good to excellent reliability across asymptomatic and symptomatic groups.
WHY TESTING BEATS GUESSING
Because low back pain so often fluctuates rather than resolving in a straight line, athletes and clinicians can end up treating “no pain today” as the signal to return to full training, without ever confirming that trunk endurance has actually been restored. That’s a meaningful gap: an athlete can be pain-free at rest and still fatigue through their back extensors well before the end of a training session or a match, at which point technique breaks down and injury risk rises.
The same principle holds across other joints in the return-to-sport literature. A 2016 Delaware-Oslo cohort study by Grindem and colleagues found an 84% lower reinjury rate in athletes cleared using objective discharge criteria rather than time alone, and a related study by Kyritsis and colleagues found a fourfold higher reinjury risk in athletes who didn’t meet full discharge criteria. Trunk endurance testing applies the same logic to the lower back: a number that has to be met, not a symptom that simply has to be absent.
THE KINETIC CHAIN COST OF CUTTING CORNERS
A fatiguing back extensor doesn’t fail in isolation. As trunk endurance drops, athletes typically lose postural control earlier in a session, which changes how load is transferred down into the hips and up through the shoulders during running, lifting, and repeated bending. This kind of load redistribution, where an underprepared segment pushes risk onto the joints around it, is well documented elsewhere in return-to-sport research: a 2016 systematic review by Wiggins and colleagues found that athletes returning to sport after ACL reconstruction reinjured the same knee and the opposite knee at almost identical rates, illustrating how an untested weak link doesn’t just risk itself, it changes the loading pattern of everything connected to it.
Biering-Sørensen’s own findings make the long-term stakes clear: reduced back extensor endurance was directly predictive of who developed low back trouble over the following year. Confirming trunk endurance before returning to full training or competition is one of the more practical ways to interrupt that pattern before it becomes a recurring, low-grade problem that follows an athlete from one season into the next.
WHAT WE DO AT PRAXIS
We use the Biering-Sørensen test alongside movement screening and graded loading through the trunk and hips to confirm the back is genuinely ready for full training, not just quiet at rest. If you’re managing low back pain or returning from a back injury, book a return-to-sport assessment with our team.
Until next time, Praxis What You Preach…
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References
Biering-Sørensen F. Physical measurements as risk indicators for low-back trouble over a one-year period. Spine. 1984;9(2):106-119.
Latimer J, Maher CG, Refshauge K, Colaco I. The reliability and validity of the Biering-Sørensen test in asymptomatic subjects and subjects reporting current or previous nonspecific low back pain. Spine. 1999;24(20):2085-2090.
Grindem H, Snyder-Mackler L, Moksnes H, Engebretsen L, Risberg MA. Simple decision rules can reduce reinjury risk by 84% after anterior cruciate ligament reconstruction: the Delaware-Oslo ACL cohort study. British Journal of Sports Medicine. 2016;50(13):804-808.
Kyritsis P, Bahr R, Landreau P, Miladi R, Witvrouw E. Likelihood of ACL graft rupture: not meeting six clinical discharge criteria before return to sport is associated with a four times greater risk of rupture. British Journal of Sports Medicine. 2016;50(15):946-951.
Wiggins AJ, Grandhi RK, Schneider DK, Stanfield D, Webster KE, Myer GD. Risk of secondary injury in younger athletes after anterior cruciate ligament reconstruction: a systematic review and meta-analysis. American Journal of Sports Medicine. 2016;44(7):1861-1876.