Background: The gluteals have unique morphology related to muscle endurance, including moderate fiber sizes and a majority of Type I endurance fibers. Evidence suggests gluteal endurance is related to several classifications of low back pain, work-related musculoskeletal disorders, running kinematics, balance, and pelvic posture. However, there exists a lack of reliable and valid measures specific to gluteal endurance. Purpose: This study aims to examine the intra- and inter-rater reliability of two gluteal endurance measures (GEMs) convenient for clinical use. It also aims to provide validity for the two measures by using electromyography, recording subjective reasons for task failure, and analyzing the differences between subjects with and without recurrent low back pain (LBP). Study Design: Cross-Sectional. Methods: Sixty-eight males and females aged 18–35 years were recruited from a university population. Electromyography electrodes were placed on subjects’ dominant gluteus maximus and gluteus medius, and each subject performed three trials of each of the two GEMs, GEM-A and GEM-B. Hold times, EMG median frequency (MF) data, and subjective reasons for task failure were analyzed. Results: Bot GEMs demonstrated high intra-rater reliability and inter-rater reliability. The MF slopes of both GEMs were also highly reliable. Mean hold times were 104.83 plus or minus 34.11 seconds for GEM-A and 81.03 plus or minus 24.79 seconds for GEM-B. No statistically significant difference was found between subjects with and without LBP. Median frequency data validated gluteus maximus and gluteus medius fatigue during both measures. Posterolateral hip fatigue was reported as the primary reason for task failure in 93% and 86% of subjects for GEM-A and GEM-B, respectively. Conclusion: This seminal study of GEM-A and GEM-B found both measures to be reliable and valid measures of gluteal endurance. Further examination of the GEMs in samples with different types of LBP or hip pain is recommended.
