Validity and reliability of the modified sphygmomanometer test for assessing upper limb and trunk muscle strength in adolescents.

The Modified Sphygmomanometer Test (MST) is a method for assessing muscle strength that offers objective measures similar to those of a portable dynamometer, while also being cost-effective. However, previous studies have not investigated the measurement properties of the MST in adolescents. Thus, the objectives of the study were (1) to examine the concurrent criterion validity, test-retest and interrater reliability of the Modified Sphygmomanometer Test (TMS) for assessing muscle strength in adolescents, (2) to calculate the Standard Error of Measurement (EPM) and the smallest real difference (SRD) of muscle strength values; and (3) analyze the different forms of operationalization and their influence on the results obtained. Fifty-two adolescents (mean age: 16.5 ± 0.70 years) participated in the study. Muscle strength of the upper limbs (UL) and trunk was assessed using the MST and portable dynamometers. The Spearman test was used to determine concurrent criterion validity and the intraclass correlation coefficient (ICC) was used to assess reliability (α = 0.05). To analyze the stability of the measurements (SEM and SRD), the 95% test-retest confidence interval (CI) and inter-rater reliability were considered for all data collected. ANOVA was performed to explore different methods of operationalizing the MST. Criterion validity, test-retest reliability and moderate to very high inter-rater reliability (0.61≤r ≤ 0.94; p < 0.001; 0.63≤ICC≤0.97; p < 0.001) were found for the groups assessed muscles and different forms of operationalization, with no statistically significant differences between the different operationalization approaches. Therefore, the MST demonstrated adequate measurement properties for assessing muscle strength in adolescents.