Reliability of Shoulder Rotators Isometric Strength Test using a Novel Pulley Electromechanical Dynamometer. Influence of the Assessment Position

Abstract

Background: The shoulder complex, because of its relatively extensive freedom of motion, offers a great variety of testing positions and articular planes for strength examination. Despite this, reliability of results are not clearly addressed. A novel pulley electromechanical dynamometer (FED) (functional electronic dynamometer) could be an alternative in strength assessment, however, the relative and absolute reliability have not been reported in the literature. Objectives: To report the results of shoulder internal (IR) and rotators (ER) peak torque reliability in two assessment positions by FED in asymptomatic subjects. Methods: Fifty-two healthy college students were included and tested twice within a two week period. In a supine position, the subjects randomly performed four isometric strength tests (i.e. IR at 40°, IR at 90°, ER at 40°, and ER at 90°of shoulder abduction). Results: The intra-class correlation coefficients (ICC) for relative reliability at 90°were 0.96 (0.94 -0.98) for IR and 0.94 (0.90 -0.96) for ER. ICC at 40°were 0.89 (0.80 -0.94) for IR and 0.97 (0.94 -0.98) for ER. Absolute reliability expressed as standard error of measurement compared to the mean (SEM%) and 95% confidence interval (CI) of minimal detectable change percentage (MDC%) at 90°w ere 8.8% (-20.8, 28.4%) and 11.4% (-28.0, 35.2%) for ER. MDC% at 40°were 12.6% (-35.5, 34.8%) for IR and 18.1% (-28.1, 35, 2%) for ER. Conclusions: Isometric strength testing protocol using FED showed an excellent reproducibility and can be safely used in clinical settings to monitor the strength changes in a group of individuals or in a single individual.

Muscle quality index and isometric strength in older adults with hip osteoarthritis

“…Maximum voluntary isometric contraction of the hip joint muscles was measured using a functional electromechanical dynamometer (DEMF) on the non-dominant leg. The DEMF allows isometric assessment of muscle strength (5-3000N) with a sampling frequency of 1,000 Hz (Dynasystem, Model Research, Granada, Spain) (Chamorro et al, 2018; Vega et al, 2018). The peak of maximum force (PF) expressed in newtons was used for further analysis.…”

Reliability of isometric and isokinetic trunk flexor strength using a functional electromechanical dynamometer

“…Unlike other isokinetic devices, this device (DynaSystem, Model Research, Granada, Spain) generates linear isokinetic speeds between other dynamic modes (tonic, kinetic, elastic, inertial, conical) to static (isometric, vibratory) allowing to evaluate and train through resistance/velocity constant and variable (Campos Jara et al, 2014). Furthermore, it has been described as a valid and reliable measurement method for evaluating upper and lower extremity muscle strength (Cerda Vega et al, 2018; Chamorro et al, 2018). This technology has been used to study the isometric strength of the shoulder rotators and hip abductor and has obtained high reliability values (ICC > 0.94; CV < 10%) (Cerda Vega et al, 2018; Chamorro et al, 2018).…”

Reliability of a standing isokinetic shoulder rotators strength test using a functional electromechanical dynamometer: effects of velocity

“…There is no scientific consensus about which the best position is to obtain reliable strength data in the shoulder test. The three positions most used by clinicians are supine ( Andersen et al, 2017 ; Claudio Chamorro et al, 2018 ; Forthomme et al, 2011 ), sitting ( Byram et al, 2010 ; Edouard et al, 2013 ; Radaelli et al, 2010 ) and standing ( Frisiello et al, 1994 ; Greenfield et al, 1990 ). The sitting position has been the most widely studied due to the clinical nature of the studies and to an easier stabilization of the patient when evaluating ( Edouard et al, 2011 ).…”

“…It allows us to evaluate the strength in the human being. The isometric strength of the shoulder rotators ( Chamorro et al., 2018 ) and hip abductor strength ( Cerda Vega et al., 2018 ) has been studied with this technology; however, shoulder maximal dynamic strength has not been studied yet ( Chamorro et al, 2018 ) ( Fig. 1 ).…”

“…Unlike others, this machine generates linear isokinetic speeds, dynamic modes (tonic, kinetic, elastic, inertial, conical) and statics modes (isometric, vibratory), allowing the evaluation and training through constant and/or variable resistance/velocity (Campos Jara et al, 2014). Furthermore, it has been described as a valid and reliable measurement method for evaluating upper and lower extremity muscle strength ( Cerda Vega et al., 2018 ; Chamorro et al, 2018 ). This technology has been used to study the isometric strength of the shoulder rotators and has obtained high-reliability values (ICC > 0.94; CV < 10%) ( Chamorro et al, 2018 ; Chamorro et al., 2019 ) In addition, this device has also been used to evaluate other joints such as lower limbs ( Chamorro et al, 2017 ; Fàbrica et al., 2020 ) and trunk ( Rodriguez-Perea et al, 2019 ).…”