Norms for an isometric muscle endurance test

Musculoskeletal performance assessment is critical in the analysis of physical training programs in order to prioritize goals for decreasing injury risk and focusing performance goals. Abdominal endurance as part of this analysis is often assessed with techniques that have validity that has been debated in literature. The purpose of this study was to develop normative sex- and athlete-specific percentiles for a trunk stabilization and muscular endurance by using a prone forearm plank test in college-aged students. A second purpose of this study was to investigate the effect of habitual physical activity and the reason for test termination. There were 471 participants (means ± SE; males: n = 194, age 20.4 ± 0.2 years, body height 179.4 ± 0.5 cm, body mass 81.1 ± 1.2 kg; females: n = 277, age 20.2 ± 0.2 years, body height 165.7 ± 0.4 cm, body mass 63.9 ± 0.7 kg) who performed this test to volitional or technique failure. Males produced significantly higher test durations than females (means ± SD; 124 ± 72 seconds vs. 83 ± 63 seconds) and athletes produced significantly longer test durations than non-athletes (123 ± 69 s vs. 83 ± 63 s) but no interaction effects were seen in the variables of sex and athletic status. The activity level was found to have a threshold of influence (>3 times/week) on abdominal endurance that is dose-specific where greater than 5 times/week showed the greatest influence. The fatigue of the abdominals was the termination reason producing the lowest test duration and there was no sex effect on reason for test termination. These normative percentiles for abdominal endurance suggest that the abdominal plank test can now be used as an alternative to other abdominal assessments in college students, but further investigation is warranted prior to confirmation and generalization to other populations.