Validity and reliability of evaluating hip abductor strength using different normalization methods in a functional electromechanical device

Abstract

The hip abductor muscles are vitally important for pelvis stability, and common strength deficits can negatively affect functionality. The muscle strength can be measured using different dynamometers and be evaluated in three positions (side-lying, standing, and supine). Obtained strength data can be expressed in different ways, with data normalization providing more objective and comparable results. The aim of this study was to establish the validity and reliability of three protocols in evaluating the isometric strength of the hip abductor muscles. A new functional electromechanical dynamometer assessed strength in three positions, with findings subjected to three data normalization methods. In two identical sessions, the hip abductor strengths of 29 subjects were recorded in the side-lying, standing, and supine positions. Peak force was recorded in absolute terms and normalized against body mass, fat-free mass, and an allometric technique. The peak force recorded in the side-lying position was 30% and 27% higher than in the standing and supine positions, respectively, independent of data normalization methodology. High inter-protocol correlations were found (r: 0.72 to 0.98, p ≤ 0.001). The supine position with allometric data normalization had the highest test-retest reliability (0.94 intraclass correlation coefficient and 5.64% coefficient of variation). In contrast, the side-lying position with body mass data normalization had a 0.66 intraclass correlation coefficient and 9.8% coefficient of variation. In conclusion, the functional electromechanical dynamometer is a valid device for measuring isometric strength in the hip abductor muscles. The three assessed positions are reliable, although the supine position with allometric data normalization provided the best results.

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.…”

Differences in Utilization of Lower Limb Muscle Power in Squat Jump With Positive and Negative Load

“…From these, the three with the best fit to the theoretical model, those where the error term was lower (see later data processing or Ferraro and Fábrica, 2017 , if a detailed explanation is required), were considered for subsequent analysis. Loads were controlled using a FEMD (Dynasystem ® Model Research, Symotech, Granada, Spain) in tonic mode ( Chamorro et al, 2017 ; Cerda-Vega et al, 2018 ). The dynamometer pulled on each side of a climbing harness belt placed at the subject’s waist through a low-friction pulley system similar to that used by Markovic and Jaric (2007) and Cuk et al (2014) ( Figure 1 ).…”

“…On the other hand, this can imply a risk on landing, since when descending, the belts re-tension, destabilizing if it is a discharge or increasing the load on landing if it is an increase in load (downward pull). A new multiple-joint isokinetic dynamometer ( Dvir and Müller, 2019 ), used to control the loads in different free movements ( Chamorro et al, 2017 ; Cerda-Vega et al, 2018 ), would solve this problem. This system allows carrying out of a quantitative control of the load, keeping it constant during the movement variation that takes place during the impulse time and ceasing to act once the subject takes off from the ground.…”

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

“…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 ).…”