Effects of upper-limb exoskeleton on muscle activity in tasks requiring arm elevation: Part II - In-field experiments in construction industry settings.

Background: The body of literature regarding the use of an upper limb exoskeleton during authentic working conditions is sparse. Objective: The aim of this study was to evaluate the effectiveness of an upper limb exoskeleton in reducing muscle strain during authentic industrial construction work. Methods: Fifteen male participants, comprising of roofers, scaffolders, builders, bricklayers, and graders performing overhead work participated in the study. During work without (REF) and with exoskeleton (EXO), muscle activity from 8 muscles, heart rate (HR), metabolic equivalent (MET), and upper arm elevation angles were recorded. Results: When using the exoskeleton, a significant reduction of 20.2% in average muscle activity of 8 muscles was found. The largest effect focused on m. deltoideus, where 46.2 and 32.2% reduction occurred in medial and anterior parts of the muscle, respectively. HR and MET were unaffected. Upper arm elevation angles were similar between REF and EXO, indicating equal biomechanical loading. Conclusions: This study indicates that exoskeletons show great promise in reducing the potential for musculoskeletal strain during authentic overhead construction work.

Home Care Workers' Objective and Subjective Recovery From Work.

OBJECTIVE: The aim of this cross-sectional study was to examine the recovery from work in Finnish home care nurses with objective and subjective recovery measures. METHODS: Heart rate and heart rate variability recordings were performed in home care nurses over a period of one work shift and the following night. Following the measurements, the participants ( N = 91) answered a questionnaire including questions about their self-rated recovery from work and sleep disturbances. RESULTS: The objectively measured recovery was within the recommended heart rate variability range, yet the self-rated recovery from work was only mediocre. Subjective recovery was not associated with objectively measured recovery. CONCLUSIONS: There is a discrepancy between objectively and subjectively measured recovery from work. Therefore, an additional objective method in occupational field studies, along with questionnaires, is recommended to measure physiological recovery.

Effects of an exoskeleton on muscle activity in tasks requiring arm elevation: Part I - Experiments in a controlled laboratory setting.

BACKGROUND: Long-term work with elevated arms, or overhead work, is a risk factor for musculoskeletal complaints and disorders. Upper-limb exoskeletons are a promising tool for reducing occupational workload when working with hands above shoulder level. OBJECTIVE: The purpose of this study was to assess the effects of upper-limb exoskeleton on muscular and physical strain and perceived exertion during dynamic work at four different shoulder joint angles. Further, we evaluated if there are any negative effects associated with the use of exoskeleton. METHODS: A total of 15 student participants performed dynamic work in laboratory setting with and without an exoskeleton at four different shoulder angles: 60, 90, 120 and 150 degrees. Muscle electrical activity from 8 muscles of the upper body, perceived exertion, and heart rate were measured during the work task, and grip strength, muscle stiffness, tone, and elasticity from six muscles, m. deltoideus physiological cross-sectional area and muscle fiber pennation angle, and nerve conduction velocity were measured before and after the work task. RESULTS: Based on the results, the use of exoskeleton significantly reduced the muscle activity of the upper limb, shoulder, and back muscles. The reduction was most significant when the arm elevation was 120°, and in m. deltoideus muscle activity. RPE was also positively affected indicating reduction in workload when using exoskeleton. CONCLUSION: The results suggest that the use of upper limb exoskeleton has potential to reduce physical workload during overhead work and, consequently, reduce the risk for work-related musculoskeletal disorders.

Effects of workday characteristics and job demands on recovery from work among Finnish home care nurses: a multi-source cross-sectional study.

OBJECTIVE: Ageing populations and poor care workforce availability are causing increasing job demands for home care nurses across Europe. While recovery from work helps sustain work ability and wellbeing, past research has relied mainly on self-reported measures of health, stressors, and recovery. This study aims to examine how objective and subjective job demands are associated with measured day-time recovery among home care nurses. METHODS: Heart rate variability recording was conducted for 95 Finnish home care nurses. The study participants documented their work tasks throughout the workday and filled a wellbeing questionnaire. The amount of care time, breaktime, number of different weekly clients, and their care needs were obtained from the survey. The associations between job demands and measured day-time recovery were analysed using multivariate linear regression. RESULTS: The amount of day-time recovery was on average 75 min. The number of different clients during the workday (e.g., care continuity) and higher care needs of the clients were associated with lower day-time recovery. Additionally, something slightly disrupting the course of the workday was associated with increased recovery. CONCLUSIONS: Our findings indicate that reducing especially the objective job demands (workday characteristics) can contribute to better day-time recovery among home care nurses. To help sustain work ability and improve wellbeing, day-time recovery can be promoted with better work scheduling that supports care continuity and ensures sufficient care resources and support for nurses with many clients or clients with high care needs.

Increased physical workload in home care service is associated with reduced recovery from work.

OBJECTIVE: This study investigated the physical workload of home care service workers and determined whether the different intensities of physical work strain experienced by home care nurses have different impacts on their recovery from work. METHODS: Physical workload and recovery were measured among 95 home care nurses based on heart rate (HR) and heart rate variability (HRV) recordings during one work shift and the following night. Differences in the physical work strain were compared between younger (≤ 44-year-old) and older (≥ 45-year-old) employees and between morning and evening shifts. To determine the effects of occupational physical activity on recovery, HRV at all time points (during the workday, when awake and asleep, and whole measurement) in relation to the amount of occupational physical activity was examined. RESULTS: The average physiological strain during the work shift, measured as metabolic equivalent (MET), was 1.8 ± 0.5. Moreover, the occupational physical demands in relation to maximal capacity were higher for the older employees. The results of the study showed that a higher occupational physical workload reduced the HRV of home care workers during the workday, leisure time, and sleep. CONCLUSIONS: These data indicate that increased occupational physical workload is associated with reduced recovery among home care workers. Therefore, decreasing occupational strain and ensuring sufficient recovery is recommended.