The purpose of this study was to determine if a modified (MOD) testing method for previously established trunk endurance testing for flexion and extension is a reliable alternative. Fifty subjects were tested with the standard (ST) testing procedure and an MOD testing procedure on separate testing occasions 1 week apart. The testing procedure order and method of assessments were randomly selected and implemented. The MOD testing procedure used a clinician to provide stabilization as opposed to the ST method of belt stabilization. Interrater reliability for MOD procedures was 0.97 for extension and 0.93 for flexion. Correlation of the MOD procedure to the ST procedure was found to be 0.90 and 0.84 for extension and flexion, respectively. From this testing, it can be concluded in a sample of normal college-aged subjects that an MOD testing method for trunk flexion and extension endurance can reliably be used as compared with the previously accepted ST testing methods. From a practical application standpoint, this allows the use of an MOD testing procedure to be implemented in athletic training rooms and weight rooms that may not have appropriate tables for the ST testing and the fact that the MOD testing procedure will most likely require less time commitment and greater efficiency with testing of large groups of subjects.