Trunk muscle endurance tests: reliability, and gender differences in athletes.

Adequate trunk muscle endurance may play an important role in injury-free performance among athletes. However, reliability of tests of isometric trunk muscle endurance in common use has not been clearly established and few studies have reported normative data for athletes. This study first examined intra-rater and inter-rater reliability of the side bridge endurance test and a test of trunk flexor endurance in a group of non-athletes, then measured performance of a group of elite athletes on tests of trunk muscle endurance commonly used in the clinic. The side bridge endurance test and the trunk flexor endurance test were found to have high intra-rater and inter-rater reliability, albeit with relatively large standard error of measurement (S.E.M.) values. In contrast with previous studies of non-athletes, male athletes had equivalent holding times on the Biering-Sørensen trunk extensor endurance test to those of female athletes. However, female athletes had significantly lower holding times on the side bridge endurance tests than their male counterparts. The implication of the significant difference in endurance performance between male and female athletes in some muscle groups but not others is that testing and training of trunk muscle endurance should be 'multidirectional' for all athletes who aim to optimise performance and minimise injury risk.