An Empirical and Subjective Model of Upper Extremity Fatigue Under Hypogravity

Abstract

In the context of extra-terrestrial missions, the effects of hypogravity (0 < G < 1) on the human body can reduce the well-being of the crew, cause musculoskeletal problems and affect their ability to perform tasks, especially during long-term missions. To date, studies of the effects of hypogravity on human movement are limited to experiments on the lower limbs. Here, we extend the knowledge base to the upper limbs, by conducting experiments to evaluate the effect of hypogravity on upper limb physical fatigue and mental workload in participants. Our hypothesis was that hypogravity would both increase participant productivity, by reducing overall physical fatigue expressed in Endurance Time, and reduce mental workload. Task Intensity-Endurance time curves are developed especially in seated positions, while performing static, dynamic, repetitive tasks. This experiment involved 32 healthy participants without chronic problems of the musculoskeletal system aged 33.59 ± 8.16 years. Using the collected data, fatigue models were constructed for tasks of varying Intensity. In addition, all participants completed the NASA – Task Load Index subjective mental workload assessment, which revealed the level of subjective workload when executing different tasks. We found two trends in the empirical fatigue models associated with the difference between the strength capabilities of males and females. The first is a significant positive (p = 0.002) relation between Endurance time and gravity level (⅙ G Moon, ⅓ G Mars, 1G) with negative coefficient for males and females for a static task. And there is marginal relation (p < 0.1) between overall mental workload and gravity level with a positive coefficient for males and females for the same task. The same trend was observed for dynamic and repetitive tasks. We concluded that the Task Intensity-Endurance Time model, adapted to hypogravity in combination with subjective mental assessment, is useful to human fatigue investigation. The combination of these methods used for ergonomic analysis and digital human modeling, could improve worker productivity. Finally, this study may help prepare astronauts for long-term missions on the Moon and Mars and improve our understanding of how we can prevent musculoskeletal disorders caused by hazardous manual handling under such extreme environments.

Hypogravity modeling of upper extremities: an investigation of manual handling in the workplace

“…According to the Shapiro–Wilk test, all task data are regularly distributed, as shown in Supplementary Table S2 . The accuracy of OpenPose was previously assessed and discussed in the thesis of the main author “Biomechanics at the Workplace under Hypogravity” ( Volkova, 2022 ). In this article, the author provides the main results confirming the accuracy of OpenPose in a aquatic environment.…”

“…For use in underwater investigations, a numerical simplified model of adjustable weights was created, which was designed for different parts of the body (upper part) of the participants. This model is described in detail in the main author’s study ( Volkova et al, 2022 ) and the same author’s dissertation ( Volkova, 2022 ). Adjustable weights for the upper arm and forearm (Strong shop.…”

“…The asymmetric mesh was occasionally modified via Blender proportional editing 1 function ( Guevarra and Guevarra, 2020 ). According to Volkova et al (2021) , this method gives a relatively small difference in the 3D body model estimate for the total body volume compared to a water-based body volume measurement.…”

“…In this study, the angle between the spine, upper arm, and vertical axis Y was considered, as shown in Figure 4 . Other measured angles are described in the work of the main author ( Volkova, 2022 ). They are not described here because these angles did not give significant results for the development of further hypotheses related to workplace design under HG.…”

“…At present, little is known about upper limb motion under HG as most of the experiments are limited to those performed on the lower limbs ( Richter et al, 2017 ; Hewes and Spady, 1964 ; Rajulu and Klute, 1992 ; Newman and Alexander, 1993 ; Sylos-Labini et al, 2014 ; Kang et al, 2019 ; Weber et al, 2019 ). To the author’s knowledge, studies of sitting positions when performing manual handling with operational weights under HG have recently been reported only once in a publication ( Volkova et al, 2022 ) and thesis ( Volkova, 2022 ). The lack of data and objective measures of upper limb and trunk movements during task performance generates difficulties in evaluating movements and proposing the measures to mitigate the effects.…”