Abstract

The Biering-Sorensen Test (BST), the Side Bridge Test (SBT) and the Ito Test (IT) are three of the most widely used field tests to measure the strength of the trunk muscles. The aim of this study was to analyse the absolute and relative reliability of these tests and evaluate the effect of the anthropometry of the participants on test performance. The study involved 27 young (23.5 ± 4.0 years) and physically active men. Participants performed two recording sessions in which they did the three tests (8 min. recovery between tests) and where various anthropometric variables were measured. Relative reliability was good, with ICCs greater than 0.80 in all the tests, but absolute reliability was not with SEMs ranging from 13.36% in the BST to 19.89% in the IT. The IT showed a negative correlation with mass (r= –.475; p= .014) and bi-iliac diameter (r= –.404; p= .040) and the BST showed a negative correlation with mass (r= –.610; p= .001), bi-iliac diameter (r= –.546; p= .004), biacromial diameter (r= –.456; p= .019) and the acromial-iliac index (r= –.413; p= .036). The absolute reliability data call into question the utility of these tests in training programmes where participants have little margin for improvement. In addition, if comparisons are made between subjects it is important to bear anthropometric differences in mind, as the body is used as a measuring instrument during the performance of the test.