Dr. Ulloa-Diaz, David

The purpose of the study was to analyze the test–retest reliability of an isometric and isometric/vibratory muscular strength protocol in the bilateral seated bench press (BSBP), bilateral seated rowing (BSR), unilateral seated right knee extension (USKER), and left knee extension (USKEL) tests controlled using functional electromechanical dynamometry (FEMD) in healthy young adults. A repeated measures design was used to determine the reliability of a muscular strength protocol in isometric and isometric vibration modes with FEMD. No significant differences were found in test–retest analysis (p > 0.05; ES < 0.20); and high reliability (CV = 4.65–5.02%; ICC = 0.99–0.98) was found for BSBP measures, and acceptable reliability (CV = 3.71–9.61%; ICC = 0.98–0.95) was found for BSR, USKER, and USKEL. Furthermore, the coefficients between the two measures were strong (r = 0.963–0.839) and highly significant (p = 0.001) for maximal strength in the isometric and maximal isometric/vibratory assessment of muscle strength in all muscle strength tests. This study demonstrates that isometric and maximal isometric/vibratory strength in the BSBP, BSR, USKER, and USKEL tests can be measured with high reliability and reproducibility using the FEMD.

Background: Systematizing reliable protocols and procedures for strength assessment in handball has allowed for a more thorough kinetic analysis and increased precision in detecting training-induced changes in muscular strength. The evaluation of upper limb strength with a bilateral standing press (BSP) exercise in handball players approximates blocking actions in the defensive phase, pushing and fixation. Aim: The aim of this study was to analyze the relative and absolute reliability of intra-session comparisons in an isometric peak muscle strength protocol in a bilateral standing press (BSP) exercise among female handball players. Methods: Sixteen young female handball players at an international level, aged between 22 ± 4 years, with no prior experience in using functional electromechanical dynamometers (FEMD) participated in this study. The participants initiated the assessment of maximum isometric force in a bipedal stance with a forward projection of the dominant foot between 20 and 30 cm. The knees were kept semi-flexed, and the hip extension of the non-dominant limb ranged from 15 to 20°. Bilateral anterior push of the upper limb was performed with shoulder abduction and elbow flexion at 90°, maintaining a pronated hand position. Participants were instructed to exert three sets of maximal force for 5 s in BSP exercise. Relative reliability was assessed using the model intraclass correlation (ICC) and absolute reliability was assessed using the coefficient of variation (CV) and standard error of measurement (SEM). For this study, the parameters of maximum and mean muscle strength were considered. Results: The results demonstrated high relative reliability (ICC 0.93–0.97) and absolute reliability (SEM 0.19–2.79) y (CV 4.78–9.03) for both mean force and peak force, with no significant differences between the sets (p > 0.05), indicating a negligible effect size (0.01−0.12). Conclusion: The mean and peak isometric muscle strength for the BSP exercise controlled with FEMD in female handball players exhibits high relative and absolute reliability between series.

Purpose: This study aimed to examine the reliability of trunk extensor strength assessment with a functional electromechanical dynamometer (FEMD). Methods: Thirty-one men performed strength assessment at different velocities (V) (V1 = 0.15 m·s−1, V2 = 0.30 m·s−1, V3 = 0.45 m·s−1) and range of movement (R) (R1 = 25% cm; R2 = 50% cm), and isometric contraction at 90º. Reliability was obtained through the intraclass correlation coefficient (ICC), typical error (TE), and coefficient of variation (CV). Results: The absolute reliability provided stable repeatability of the average eccentric strength in the V1R1 condition (CV = 9.52%) and the maximum eccentric strength in V1R1 (CV = 9.63%) and V2R2 (CV = 9.66%). The relative reliability of the trunk extensor’s average strength was good (ICC = 0.77–0.83) for concentric and good (ICC = 0.78–0.85) and moderate (ICC = 0.67–0.74) for eccentric contraction. Also, good (ICC = 0.77–0.81) and moderate (ICC = 0.55–0.74) reliability of the maximum strength were obtained for concentric and eccentric contraction. The most reliable manifestation to evaluate the concentric (CV = 11.33%) and eccentric (CV = 9.52%) strength was the average strength in the V1R1 condition and the maximum strength (CV = 10.29%) to isometric assessment. The average concentric strength in the V2R2 condition (r = 0.69) and the maximum eccentric strength in the V1R1 condition (r = 0.65) were the best related to the maximum isometric strength. Conclusions: FEMD is a highly reliable device to evaluate trunk extensors strength.