Biering-Sorensen test is an isometric back endurance test. Biering-Sorensen test scores have varied in different cultural and occupational groups. The aims of this study were to collect normative data on Biering-Sorensen holding times, to determine the discriminative ability of the Biering-Sorensen test in Turkish coal miners, and to examine the association between Biering-Sorensen test result and functional disability.

One hundred and fifty male coal miners participated in this study. Trunk extensor muscle strength was measured using the Biering-Sorensen test. Oswestry disability index was used to measure the functional disability level of low back pain.

The mean Biering-Sorensen holding time for the total subject group was 107.3±22.5s. The mean time of Biering-Sorensen test of the subjects with and without low back pain were 99.9±19.8 and 128.6±15.2s, respectively. The difference between the subjects with and without low back pain was statistically significant (p<0.001). There was a statistically significant negative correlation between Oswestry functional disability score and Biering-Sorensen holding time (r=−0.824, p<0.001).

Turkish coal miners have low mean back extensor endurance holding times. Biering-Sorensen test had a good discriminative ability in our study group. Trunk muscle strength has a significant effect on the disability level of low back pain. Thus trunk muscle endurance training exercise therapy may be effective for the reduction of disability in patients with low back pain.