Tests to Measure Core Stability in Laboratory and Field Settings: Reliability and Correlation Analyses.

Although core stability (CS) has been assessed through many different tests, the relationships among them are currently unknown. The main objective was to analyze the relationship between 5 representative tests used to assess CS in: (1) laboratory settings: Sudden Loading Test (SLT) and Stable and Unstable Sitting Test (SUST) and (2) field settings: Biering-Sørensen Test (BST), 3-Plane Core Strength Test, and Double-Leg Lowering Test. The reliability of these tests was also examined. In total, 33 recreationally active males performed the tests twice. The relationship between all variables was examined using Pearson correlation coefficient in those variables with a good reliability. Only stiffness and angular displacement in the SLT, dynamic unstable tasks in the SUST, and the holding time in the BST showed good reliability (intraclass correlation coefficient: .63-.91, typical error: 9.8%-21.0%). Few and low correlations were observed between the SLT, SUST, and BST. Despite finding several significant correlations among the dynamic unstable tasks of the SUST (r ≥ .807, P < .01), no correlations were found between the loading directions of the SLT. The absence of correlations between these tests suggests that CS measurements are not generalizable, as they probably assess different dimensions of CS, or in the case of the BST, a different capacity (ie, trunk extensor endurance).

Reliability of the Star Excursion Balance Test and Two New Similar Protocols to Measure Trunk Postural Control.

BACKGROUND: Although the Star Excursion Balance test (SEBT) has shown a good intrasession reliability, the intersession reliability of this test has not been deeply studied. Furthermore, there is an evident high influence of the lower limbs in the performance of the SEBT, so even if it has been used to measure core stability, it is possibly not the most suitable measurement. OBJECTIVE: (1) To assess the absolute and relative between-session reliability of the SEBT and 2 novel variations of this test to assess trunk postural control while sitting, ie, the Star Excursion Sitting Test (SEST) and the Star Excursion Timing Test (SETT); and (2) to analyze the relationships between these 3 test scores. DESIGN: Correlational and reliability test-retest study. SETTING: Controlled laboratory environment. PARTICIPANTS: Twenty-seven physically active men (age: 24.54 ± 3.05 years). METHOD: Relative and absolute reliability of the SEBT, SEST, and SETT were calculated through the intraclass correlation coefficient (ICC) and standard error of measurement (SEM), respectively. A Pearson correlation analysis was carried out between the variables of the 3 tests. MAIN OUTCOME MEASURES: Maximum normalized reach distances were assessed for different SEBT and SEST directions. In addition, composite indexes were calculated for SEBT, SEST, and SETT. RESULTS: The SEBT (dominant leg: ICC = 0.87 [0.73-0.94], SEM = 2.12 [1.66-2.93]; nondominant leg: ICC = 0.74 [0.50-0.87], SEM = 3.23 [2.54-4.45]), SEST (ICC = 0.85 [0.68-0.92], SEM = 1.27 [1.03-1.80]), and SETT (ICC = 0.61 [0.30-0.80], SEM = 2.31 [1.82-3.17]) composite indexes showed moderate-to-high 1-month reliability. A learning effect was detected for some SEBT and SEST directions and for SEST and SETT composite indexes. No significant correlations were found between SEBT and its 2 variations (r ≤ .366; P > .05). A significant correlation was found between the SEST and SETT composite indexes (r = .520; P > .01). CONCLUSIONS: SEBT, SEST, and SETT are reliable field protocols to measure postural control. However, whereas the SEBT assesses postural control in single-leg stance, SEST and SETT provide trunk postural control measures with lower influence of the lower-limbs. LEVEL OF EVIDENCE: III.

Dynamic trunk muscle endurance profile in adolescents aged 14-18: Normative values for age and gender differences.

BACKGROUND: The selection and validation of age- and gender-specific criterion-referenced cut-points for abdominal endurance are still unclear. OBJECTIVE: To stablish normative values for abdominal endurance in adolescents by age and gender using the Bench Trunk Curl-up Test (BTC). Additionally, the reliability of the BTC was analyzed. METHODS: Two hundred and sixteen untrained high school students (104 males - 112 females) were grouped into five age strata. Participants performed the BTC twice with a rest period of 72 h. Descriptive statistics and percentile scores were determined for each gender/age strata. RESULTS: Males showed higher BTC scores than females (males: 90.07 ± 32.65 repetitions; females: 73.43 ± 27.74 repetitions), but no significant differences between age strata nor age * gender interaction were found. Significant differences for the BTC scores between sessions were found (T1 = 72.06 ± 26.28 repetitions; T2 = 81.44 ± 31.27 repetitions). The ICC was 0.82, whereas the typical error was 17.2%. CONCLUSIONS: Gender, but not age, is an important factor when abdominal endurance is compared between adolescents. Finally, the BTC is a reliable test, supporting the findings of this study. However, an extensive familiarization period to reduce the learning effect is necessary.

Reliability assessment and correlation analysis of 3 protocols to measure trunk muscle strength and endurance.

Different methods have been developed to quantify trunk muscle strength and endurance. However, some important protocol characteristics are still unclear, hindering the selection of the most suitable tests in each specific situation. The aim of this study was to examine the reliability and the relationship between 3 representative tests of the most common type of protocols used to assess trunk muscle strength and endurance. Twenty-seven healthy men performed each test twice spaced 1 month apart.Trunk strength and endurance were evaluated with an isokinetic dynamometer and 2 field tests including Biering-Sørensen test and Flexion-rotation trunk test. All tests showed a good relative consistency (intraclass correlation coefficient [ICC]> 0.75), except for the isokinetic endurance variables which had low-moderate reliability (0.37 < ICC > 0.65). Absolute reliability seemed slightly better in the isokinetic protocol than in the field tests, which showed about 12% of test-retest score increase. No significant correlations were found between test scores. After a familiarisation period for the field tests, the 3 protocols can be used to obtain reliable measures of trunk muscle strength and endurance. Based on the correlation analysis, these measures are not related, which highlights the importance of selecting the most suitable trunk test for each situation.