Knee Extension Exercise Effects on Physiological and Psychophysical Performance: Normal Weight Versus Obese Office Workers.

BACKGROUND: Knee extension exercise is useful and practical for obese and overweight people as this form of exercise is effective in minimizing body weight loading on joints and improving the body's physiological function. This study aimed to compare the physiological and psychophysical parameters of office workers while computer-based working in an active workstation equipped with an active footrest (AFR) prototype with a mechanism for performing knee extension exercises in a sitting position, and also to compare the physiological and psychophysical parameters among normal-weight and obese office workers. METHODS: In this quasi-experimental study, the physiological parameters of heart rate (HR) and energy expenditure (EE) (measured with the Fitbit Charge HR smartwatch) were measured in two cross-over random sessions for 32 office workers (16 normal-weight and 16 obese) aged 28 to 50 years (M = 42.72, standard deviation [SD] = 4.37) while performing office tasks in sitting and active workstations (equipped with AFR). Perceived physical exertion, comfort, fatigue, and liking were also measured by rating the participants. FINDINGS: Short-term activity of the participants with AFR performing computer tasks significantly improved physiological and psychophysical parameters compared with the participants in sitting workstations. However, there was no significant difference in the effect of AFR on physiological and psychophysical parameters between normal-weight and obese participants. CONCLUSIONS/APPLICATION TO PRACTICE: Given the significant increase in EE and HR resulting from exercise with AFR compared with the conventional workstation, the use of AFR can help office workers achieve the minimum standard of physical activity at their workplace.

Cognitive demands and mental workload: A filed study of the mining control room operators.

Cognitive demand and mental workload assessment are essential for the optimal interaction of human-machine systems. The aim of this study was to investigate the cognitive demands and mental workload as well as the relationship between them among the mining control room operators. This cross-sectional study was performed on 63 control room operators of a large mining plant located in Iran. Cognitive demands and mental workload were assessed using cognitive task analysis (CTA) and NASA Task Load Index (NASA-TLX), respectively and the analysis was performed using SPSS version 21. Independent samples T-test, Mann-Whitney U test and multivariate linear regression were used for data analysis. Twelve cognitive demands were extracted after observing the tasks and conducting semi-structured interviews with the control room staff. The mean scores of total cognitive demands and MWL were 6.60 and 72.89, respectively, and these two indicators showed a positive and significant correlation (r = 0.286; P = 0.023). The participants' demographic characteristics such as age, education, and work experience did not affect mental workload, but the two cognitive demands (memory and defect detection) affected MWL. High cognitive demands and mental workload indicate poor interaction between humans and machines. Due to the effect of memory load and defect detection on mental workload, it is recommended to assign cognitive tasks based on memory and defect detection to the machine to reduce the mental workload and improve human-machine interaction.

Designing and usability testing of a new prototype active footrest for knee extension exercise among office workers.

Objectives. The active factor along with light exercise can reduce static muscle work and increase muscle flexibility and endurance. Accordingly, this study aimed to design and prototype a new active footrest, implemented in conventional sitting workstations, and to test its usability among office workers. Methods. The steps taken to design and prototype the active footrest were: selection of an exercise appropriate for goals of ergonomic interventions; idea development; selection of the best conceptual design; design with SOLIDWORKS version 2016; and fabrication of a prototype. Afterward, usability of the active footrest prototype was assessed among 20 office workers (10 females) using field data by the system usability scale. Results. Upon completion of the design steps, the active footrest prototype was prototyped by taking into account design criteria (e.g., functionality, inclusive design, easy application and reduction of additional body movement), anthropometric data and mechanical properties. The participants rated the usability of the active workstation as 89 ± 8.21 (out of 100), indicating good usability results. Conclusion. In this study, an active footrest was designed and prototyped to perform knee extension exercise with the capability of being implemented in conventional sitting workstations.

The Relationship of Grip and Pinch Strength to Musculoskeletal Disorders in Female Carpet Weavers in Southeastern Iran, 2019.

BACKGROUND: The repetitive and prolonged exertion of grip and pinch strength are current among carpet weaver tasks. The three objectives of this study were (1) to investigate the relationship between symptoms of musculoskeletal disorders and grip and pinch strength of carpet weavers in carpet weaving workshops in Kerman province, (2) to compare the grip and pinch strength of carpet weavers with normal values, and (3) to identify the relationship between hand postures of carpet weavers during work and force exertion. METHODS: In this cross-sectional study, grip strength and key, tip and palmar pinch strengths of 101 female carpet weavers aged 20 to 71 years were measured in Kerman province, in 2018. Nordic Musculoskeletal Questionnaire (Extended version) was also used to evaluate musculoskeletal disorders. RESULTS: Bivariate and multivariate linear regression analyses showed that participants who suffered from musculoskeletal disorders had lower grip and pinch strength than others and this decrease was statistically significant in upper back, wrists/hands, and knees. Moreover, there was a significant difference between grip and three types of pinch strength of carpet weavers and normal values. Furthermore, for both hands, the grip strength in the position recommended by American Society of Hand Therapists was significantly greater than that in the normal position carpet weavers usually adopt. CONCLUSION: Based on the results, the high prevalence of musculoskeletal disorders has led to a significant decrease in the grip and pinch strength of carpet weavers. Therefore, it is necessary to undertake ergonomic interventions in designing the carpet weaving workstation.

Heat stress and physiological and perceptual strains of date harvesting workers in palm groves in Jiroft.

BACKGROUND: Outdoor workers are exposed to heat caused by atmospheric conditions and solar radiation. More specifically, those working in palm groves are more in danger of heat stresses since they harvest their crops in hot seasons. OBJECTIVE: This study was aimed at investigating heat stresses and strains in date harvesting workers in groves around Jiroft, Southeastern Iran. METHODS: This study was a descriptive-analytical one of cross-sectional type. In this study, three environmental indices including Wet Bulb Globe Temperature index (WBGT), Environmental Stress Index (ESI) and Discomfort Index (DI), the physiological strain index (PSI) as well as perceptual strain index (PeSI) were analyzed to investigate stresses and strains in workers. For this purpose, 59 date harvesting workers (36 men and 23 women) in palm groves in Jiroft were analyzed. With accordance to date harvesting season, data collection was carried out from August to September, 2017. RESULTS: In this research, the means of environmental indices including WBGT, ESI and DI were 32.77°C, 30.39°C and 33.22°C, respectively and they all revealed direct and significant correlation. Moreover, Time-Weighted Average for Wet Bulb Globe Temperature index (WBGT.TWA) was significantly different from Threshold Limit Values for Wet Bulb Globe Temperature index (WBGT.TLV). The scores of the PSI and PeSI were 2.28 and 6.61, respectively. CONCLUSION: The results of this study indicated that date picking workers were exposed to heat stress more than the reference value of WBGT recommended by American Conference of Governmental Industrial Hygienists (ACGIH). In addition, workers suffered a low degree of physiological strain and a moderate degree of perceptual strain caused by heat stress in palm groves in Jiroft.

Investigation of grip and pinch strengths in Iranian adults and their correlated anthropometric and demographic factors.

BACKGROUND: Grip and pinch strength measurement is important for objective evaluation of the function of the upper extremities in upper limbs injuries treatment and also for ergonomists as a way of optimizing the requirements of hand tool design. OBJECTIVE: The present study was conducted to investigate the correlation of anthropometric and demographic factors with hand strength as well as to develop regression models for grip and three types of pinch strengths including Tip, Key and Palmar in Iranian adult population. METHODS: The study population consisted of 1008 Iranian adults aged 20 to 107 years. Participants were selected using a stratified random sampling method from crowded places of the cities with the highest number of Persian ethnic group. Strength measurements were undertaken according to recommendations by the American Society of Hand Therapists (ASHT). RESULTS: This study found a positive and significant correlation between all measured strengths and anthropometric factors. The regression equations of grip and pinch strengths were developed for dominant and non-dominant hands. CONCLUSIONS: The results of this study provided more information about correlated factors of grip and pinch strengths. The regression equations developed in this research are applicable to clinical treatment and ergonomics programs.

Normative data of grip and pinch strengths in healthy adults of Iranian population.

BACKGROUND: Measuring and comparing grip and pinch strengths with their normative data is a valid method to detect intensity of the numerous damages of hand. This research was carried out with the aim of establishing normative data of grip strength and three types of pinch strengths (Tip, Key and Palmar) in healthy Iranian adults. METHODS: In this cross-sectional study, the study population was formed of 1008 people (526 men and 482 women) from healthy Fars race adults of over 20 years old in five cities of Iran. American Society of Hand Therapists (ASHT) recommendations were followed to establish normative data of grip and pinch strengths. Normative data of grip and pinch strengths were developed based on sex, 12 different age groups and dominant and non-dominant hands. Jamar dynamometer and Seahan pinch gauge were used to measure grip and pinch strengths, respectively. RESULTS: Normative data of grip and pinch strengths were provided. Grip and pinch strengths of men were significantly stronger than women. The maximum grip strength of men was obtained in the group of 20-24 years and among women it was in the age group 35-39 years. Regardless of gender, grip and pinch strengths were declined with aging. CONCLUSION: Normative data of grip and pinch strengths were developed for Iranian population.