Objective. The aim of this study was to analyze the reproducibility of a protocol using the maximal isometric strength test of the trunk in elderly women aged above 60 years, without low back pain. Methods. Twenty-one physically inactive elderly women, who had not engaged in any activity or exercise program in the past three months, participated in the cross-sectional study that consisted of two days of evaluations for the maximal isometric strength of the extensor and flexor muscles of the trunk, with a 48 h interval between the sessions. A platform with fixed seating was used, which allowed the fixation of the hip and lower limbs, with a load cell connected to a linear encoder. To verify the reliability of the test, the interclass correlation coefficient, variation coefficient, minimum detectable difference (MDD), standard error of measurement, and Bland–Altman graphs were calculated. Results. No statistical difference was observed between the first and second evaluation, which indicates that there was no learning effect. Interclass correlation coefficient values were classified as very high and high for extensor (0.98) and flexor (0.86) muscles, respectively, besides low variation (9% for both muscle groups) and acceptable values for minimum detectable difference (extensors = 51.1 N, flexors = 48.9 N). In addition, the Bland–Altman analysis revealed low bias and values within the limits of agreement. Conclusion. It is concluded that the test of maximum isometric strength of the trunk in healthy and trained elderly people presents high reliability. These values proved to be reliable if performed in at least two evaluation sessions, which confirms the hypothesis of the authors by the consistency of the measurement test.

Background: There are a limited number of tests for the assessment of shoulder and pelvic girdle stability. Reliable instruments are important to evaluate movement dysfunction at these joints in order to provide more objective parameters. Objective: To evaluate the inter-day reliability of the Upper Body Test in young adults. Methods: A reliability study was carried out with three assessments of the shoulder and pelvic girdle stability within 48-h intervals (Monday, Wednesday, and Friday). The OctoBalance ® platform was used to perform the Upper Body Test in 31 active young adults (24.5 ± 8 years). Intraclass Correlation Coefficient (ICC 2,2) two-way mixed model, Coefficient of Variation, and Bland-Altman plots were used to verify the reliability of the test. The standard error of measurement (SEM) and the minimum detectable difference (MDD 95%) were calculated for clinical applicability. Results: The Intraclass Correlation Coefficient ranged from 0.87 to 0.94-Featuring a mean difference of 0.89 (95%CI = −0.19-1.97) to left and 0.95 (95%CI = −0.38-2.27) for the right side, with a low variation coefficient (3.31-5.91%) between the second and third days of assessment. There was a statistically significant difference between the first assessment day and the other test sessions. The Bland-Altman analyses revealed low bias with scores within the limits of agreement. Minimum detectable difference scores were between 4.02 and 5.10, and standard error of measurement between 1.75 and 2.72, depending on the movement side. Conclusion: The Upper Body Test presented good inter-day reliability for assessing the stability of the shoulder and pelvic girdle in young active healthy adults.