Evaluation of bilateral force deficit in shoulder flexion using a handheld dynamometer in healthy subjects

Abstract

[Purpose] This study aimed to develop a simple, inexpensive, and accurate method for measuring the strength of shoulder flexion (Experiment 1) and evaluate the bilateral force deficit in shoulder flexion (Experiment 2) in healthy subjects. [Subjects and Methods] In Experiment 1, maximal voluntary contractions (MVCs) in isometric shoulder flexion were measured on both sides using an isometric dynamometer (ID) and a hand-grip dynamometer (HGD), as an alternative dynamometer, in six subjects. In Experiment 2, bilateral force deficit was evaluated using HGD in 21 subjects who performed unilateral and bilateral MVCs in isometric flexions of the shoulder. The peak value of electromyography (PVE) in the lateral head of the biceps brachii and anterior deltoid was measured during MVCs. [Results] In Experiment 1, ID and HGD showed almost similar coefficients of variation. A strong positive correlation was found between the values obtained using the two methods. In Experiment 2, the bilateral force deficit in shoulder flexion associated with a reduced PVE (‒10.9%) was found in 85.7% of subjects. [Conclusion] The reproducibility of measurements was similar between ID and HGD. HGD could evaluate the bilateral force deficit in shoulder flexion and is a practical tool for measuring shoulder strength.

Effects of motor imagery combined with action observation training on the lateral specificity of muscle strength in healthy subjects

“…The muscle electrical activity was not significantly altered in the MI + AO group despite improvements in bilateral force deficit. This finding is in contrast with the earlier studies showing a concomitant reduction in electrical activity during bilateral exertions (21,25) and shoulder flexion (30). In contrast, Comwell et al (7) showed no concomitant relationship between muscle strength and muscle in MI + AO was unclear.…”

“…For such individuals, motor imagery (MI) combined with action observation (AO) (i.e., MI + AO) is a promising approach for sustaining and/or increasing muscle effect of MI + AO. One week before the MI + AO training, maximal voluntary contraction (MVC) strength during bilateral and unilateral isometric shoulder flexion was measured using an isometric dynamometer (TKK5401; Takei Scientific Instruments Co. Ltd., Niigata, Japan) (30). Thereafter, the subjects were divided into control and MI + AO groups such that the average values of bilateral MVC strength during shoulder flexion were more or less identical between the groups.…”

“…Individual measurements of muscle strength were conducted at the same time of the day to reduce the effects of diurnal variations on maximal muscle strength in a randomized order with a 10-min rest period between bilateral and unilateral tests. The details of the methodology have been described elsewhere (30). Briefly, subjects were seated on a chair with their back rested straight on a backrest to fix their trunks during measurements.…”