Study of the impact of using the industrial exoskeleton to support the upper limbs on the condition of the arms and shoulder girdle muscles
Authors: Shuporin Evgeniy S. , Novozhilova Anastasia A. , Geregei Andrei M. , Shitova Evgeniya S. , Nikiforuk Anastasia I. , Podoprosvetov Alexey V. , Orlov Igor A. 
Published: August 2023

Introduction. The level of occupational morbidity associated with the effects of physical overload and overstrain of individual organs and systems indicates the need for timely and effective prevention, one of the means of which is the introduction of a promising type of PPE — industrial exoskeletons. Since there are no clear requirements and criteria of their safety and efficiency, all the researches in this field are of experimental character, which dictates the necessity of testing each particular type of exoskeleton in relation to the performance of certain labor operations.
The study aims assess the influence of using industrial exoskeleton for support of upper limbs on the arm and shoulder girdle muscles fatigue.
Materials and methods. The researchers used the presented industrial exoskeleton designed to reduce the load on the upper limbs when performing work above the level of the user's head. Eleven healthy volunteers participated in the study. In laboratory conditions, the authors simulated labor activity similar to work on an automobile conveyor with a gravity class 3.2.
During the work, both without the use of an industrial exoskeleton and with its use, scientists measured the bioelectric activity of the muscles of the upper extremities and shoulder girdle on both sides using surface EMG. In addition, before and after the work, the authors performed myotonometry and dynamometry in order to register the biomechanical properties of the studied muscles, as well as strength and endurance of the hands.
Results. As a result of recording the EMG-signal, scientists found that the activity of the anterior deltoid muscle on the right and the biceps muscle of the shoulder on the right when using an industrial exoskeleton in work is reduced by more than 50%. The indicators of endurance and strength recorded during dynamometry decreased after performing work both with and without an exoskeleton, from 1% to 36%, but their dynamics did not fully correspond to classical ideas about the development of muscle fatigue. The analysis of myotonometry data did not show statistically significant changes in the parameters of the studied muscles.
Limitations. The limitations of this study are: a small sample size (eleven volunteers), the lack of calculation of the sample size, the use of a small set of used biomedical methods for assessing the human condition.
Conclusion. The use of the studied industrial exoskeleton when performing simulated labor operations reduces the bioelectric activity of the main muscles involved in the work, which proves its effectiveness. The developed technique of surface EMG can be used in the future when carrying out such work. Dynamometry and myotonometry did not show sufficient sensitivity in the study, which necessitates the development of special techniques for solving similar problems.
Ethics. The Local Ethics Committee of Izmerov Research Institute of Occupational Health have approved the Protocol of the study (the protocol No.3 dated 04/20/2022).