Back extensor muscle endurance test scores in coal miners in Australia.

Study Design: A cross-sectional analytic study was conducted.

Objectives: To collect normative data on back extensor endurance holding times and evaluate the discriminative validity of the Biering-Sorensen test in a group of coal miners in Australia.

Summary Of Background Data: Low back pain is a common complaint among those working in the Australian coal mining industry. One test that may be predictive of first-time episodes of low back pain is the Biering-Sorensen test of back extensor endurance strength. While this test has been evaluated in overseas sedentary populations, normative data and the discriminative ability of the test have not been evaluated with coal miners.

Methods: Eighty-eight coal miners completed a questionnaire for known risk factors for low back pain, performed the Biering-Sorensen test, and undertook a test of aerobic fitness. Data analysis was performed to describe the groups and to determine whether any significant difference existed between those with a past history of low back pain and those without.

Results: Significantly lower than expected holding times were found in this group of coal miners (mean 113 s). This result was significantly lower than demonstrated in previous studies (mean 138 s, t87 = 6.32, p < 0.001). When holding times for those with a past history of low back pain were compared with times for those with no history of low back pain, the difference was not statistically significant (t86 = 1.56, p = 0.12), nor was there a significant difference in fitness between those with a past history of low back pain and those without (t86 = 0.47, p = 0.64).

Discussion/conclusions: Coal miners in Australia have lower than normal Biering-Sorensen holding times. This lower back holding time does not differ between coal miners with a past history of low back pain and those without.