Exploratory analysis using machine learning algorithms to predict pinch strength by anthropometric and socio-demographic features.

Objectives. This study examines the role of different machine learning (ML) algorithms to determine which socio-demographic factors and hand-forearm anthropometric dimensions can be used to accurately predict hand function. Methods. The cross-sectional study was conducted with 7119 healthy Iranian participants (3525 males and 3594 females) aged 10-89 years. Seventeen hand-forearm anthropometric dimensions were measured by JEGS digital caliper and a measuring tape. Tip-to-tip, key and three-jaw chuck pinches were measured using a calibrated pinch gauge. Subsequently, 21 features pertinent to socio-demographic factors and hand-forearm anthropometric dimensions were used for classification. Furthermore, 12 well-known classifiers were implemented and evaluated to predict pinches. Results. Among the 21 features considered in this study, hand length, stature, age, thumb length and index finger length were found to be the most relevant and effective components for each of the three pinch predictions. The k-nearest neighbor, adaptive boosting (AdaBoost) and random forest classifiers achieved the highest classification accuracy of 96.75, 86.49 and 84.66% to predict three pinches, respectively. Conclusions. Predicting pinch strength and determining the predictive hand-forearm anthropometric and socio-demographic characteristics using ML may pave the way to designing an enhanced tool handle and reduce common musculoskeletal disorders of the hand.

Stress influence on real-world driving identified by monitoring heart rate variability and morphologic variability of electrocardiogram signals: the case of intercity roads.

Objectives. This study examines which of the heart rate variability (HRV) and morphologic variability (MV) metrics may have the highest accuracy in different stress detection during real-world driving. Methods. The cross-sectional study was carried out among 93 intercity mini-bus male drivers aged 22-67 years. The Trillium 5000 Holter Recorder and GARMIN Virb Elite camera were used to determine heart rate and vehicle speed measurements along the path, respectively. We considered the HRV and MV metrics of electrocardiogram (ECG) signals including the mean RR interval (mRR), mean heart rate (mHR), normalized low-frequency spectrum (nLF), normalized high-frequency spectrum (nHF), normalized very low-frequency spectrum (nVLF), difference of normalized low-frequency spectrum and normalized high-frequency spectrum (dLFHF), and sympathovagal balance index (SVI). Results. The analysis showed that the HRV metrics mHR, mRR, nVLF, nLF, nHF, dLFHF and SVI are effective in mental stress detection while driving as compared to rest time. We obtained a high accuracy of stress detection for MV metrics as compared to the traditional HRV analysis, of approximately 92%. Conclusions. Our findings indicate that driver stress could be detected with an accuracy of 92% using MV metrics as an accurate physiological index of the driver's state.

A comparative investigation of machine learning algorithms for predicting safety signs comprehension based on socio-demographic factors and cognitive sign features.

This study examines whether the socio-demographic factors and cognitive sign features can be used for envisaging safety signs comprehensibility using predictive machine learning (ML) techniques. This study will determine the role of different machine learning components such as feature selection and classification to determine suitable factors for safety construction signs comprehensibility. A total of 2310 participants were requested to guess the meaning of 20 construction safety signs (four items for each of the mandatory, prohibition, emergency, warning, and firefighting signs) using the open-ended method. Moreover, the participants were asked to rate the cognitive design features of each sign in terms of familiarity, concreteness, simplicity, meaningfulness, and semantic closeness on a 0-100 rating scale. Subsequently, all eight features (age, experience, education level, familiarity, concreteness, meaningfulness, semantic closeness, and simplicity) were used for classification. Furthermore, the 14 most popular supervised classifiers were implemented and evaluated for safety sign comprehensibility prediction using these eight features. Also, filter and wrapper methods were used as feature selection techniques. Results of feature selection techniques indicate that among the eight features considered in this study, familiarity, simplicity, and meaningfulness are found to be the most relevant and effective components in predicting the comprehensibility of selected safety signs. Further, when these three features are used for classification, the K-NN classifier achieves the highest classification accuracy of 94.369% followed by medium Gaussian SVM which achieves a classification accuracy of 76.075% under hold-out data division protocol. The machine learning (ML) technique was adopted as a promising approach to addressing the issue of comprehensibility, especially in terms of determining factors affecting the safety signs' comprehension. The cognitive sign features of familiarity, simplicity, and meaningfulness can provide useful information in terms of designing user-friendly safety signs.

An integrated DEMATEL-ANP approach for identification and prioritization of factors affecting fall from height accidents in the construction industry.

Objectives. The decision-making trial and evaluation laboratory (DEMATEL) technique integrated with the analytic network process (ANP) is used for determination and prioritization of cause-effect relationships among factors affecting construction falls. Methods. Considering the 135 fall accidents collected between 2013 and 2018 from 15 residential construction projects, 70 factors and sub-factors affecting the occurrence of construction falls were determined based on safety experts' opinions. Questionnaires based on the former and the latter were then distributed among 10 occupational health and safety specialists to determine the effectiveness of the factors. The interactions and important degree of each factor are specified, using the DEMATEL-ANP approach. Results. Findings showed that organizational factors and their sub-factors have the greatest impact on construction falls and were considered as causal variables (D - R > 0), while individual and environmental factors were considered as the effect variables (D - R < 0). The results of prioritization using the ANP method showed that the work platform altitude, psychological/occupational stresses and interactions were ranked as the first through third priorities affecting the falls, respectively. Conclusions. It is necessary to implement a systematic strategy to reduce the unsafe conditions in construction projects and to pay more attention to organizational factors.

The impact of noise exposure and work posture on job stress in a food company.

BACKGROUND: In most food companies, workers are constantly exposed to non-standard levels of noise. Also, food production processes require intense manual labor and repetitive movements, which may result in musculoskeletal disorders (MSDs). Noise and awkward posture are considered as two important physical factors in the industrialized world, which can related to perceived stress. OBJECTIVE: This study was conducted among food factory workers to investigate the impact of noise exposure and work posture on occupational stress. METHODS: A total of 200 workers were examined in this cross-sectional study. Individual noise exposure was measured by TES-1354 dosimeter (TES, TW) according to ISO 9612. Postural risk and job stress levels were assessed using Quick Exposure Check (QEC), and the Osipow occupational stress questionnaire, respectively. RESULTS: The level of noise exposure and awkward posture were significantly associated with work-related stress.The relationship of gender with occupational stress was also statistically significant. CONCLUSIONS: Considering that the noise exposure and work posture factors are important determinants of work-related stress, a combined approach to eliminate the levels of non-standard noise and inappropriate posture is essential for promoting psychological health in food companies.

Hand functionality in dentists: the effect of anthropometric dimensions and specialty.

Objectives. This study aimed to investigate the relationship between dentists' hand functionality (handgrip, tip-to-tip pinch, key pinch and palmar pinch strengths) and dental specialty (maxillofacial surgery, endodontics, pediatric dentistry), socio-demographic factors and hand-forearm anthropometric dimensions. Methods. A cross-sectional study was designed in which 720 certified dentists (330 males and 390 females) voluntarily participated in the study. A tape measure (±0.1 cm) and a digital caliper (±0.1 mm) were used to measure anthropometric dimensions. A Jamar dynamometer and pinch gauge were used to measure hand strength variables. Results. Hand strengths decreased with age and clinical experience, and were always greater in male than female dentists. Maxillofacial surgeons aged 35-39 years attained the highest values of handgrip and key pinch strengths, while endodontists aged 30-34 years attained the peak values of tip-to-tip pinch strength. Among the measured hand dimensions, forearm circumference was significantly greater in maxillofacial surgeons compared with endodontists and pediatric dentists. Conclusion. Hand functionality is specialty-related among dentists because distinct dental specialties expose practitioners to different task demands. Like any other manual workers, dentists need more ergonomic and usable hand tools tailored not only to the intended application but also to the anthropometry of users.

Normative data for handgrip strength in Iranian healthy children and adolescents aged 7-18 years: comparison with international norms.

BACKGROUND: Grip strength is an essential component of physical fitness. The objective of this study was to develop normative handgrip strength data for Iranian healthy boys and girls comparing their handgrip strength with international reference values. METHODS: Handgrip strength was measured in 2637 healthy children/adolescents (1391 boys and 1246 girls), aged 7-18 years, using a standard adjustable Jamar hand dynamometer (Model 5030 J1, Sammons Preston Rolyan, Bolingbrook, IL, USA). Body mass (kg) and stature (cm) were measured and body mass index was computed in kg/m2. The sample was stratified by gender, age, and hand preference. RESULTS: Handgrip strength increased with age and was considerably higher in boys than in girls for all age groups (p < 0.001). Grip strength had a parallel and linear growth for both genders until the age of about 11 years and showed a steeper upward slope in boys than in girls thereafter. The findings of the current investigation were significantly different from those of the previously published normative data, especially for boys over the age of 12 years and girls in the age range of 7-18 years (p < 0.001). This difference was mainly in such a way that the Iranians had lower handgrip strength. CONCLUSIONS: The differences between present results and those of similar available in the literature in this field emphasize the significant role of using normative data specific to a particular population in research or clinical settings.

Analysis of hand-forearm anthropometric components in assessing handgrip and pinch strengths of school-aged children and adolescents: a partial least squares (PLS) approach.

BACKGROUND: The purpose of this study was to examine the influence of hand-forearm anthropometric dimensions on handgrip and pinch strengths among 7-18 years children and adolescents and to investigate the extent to which these variables can be used to predict hand strength. METHODS: Four types of hand strengths including handgrip, tip to tip, key, and three-jaw chuck pinches were measured in 2637 healthy children and adolescents (1391 boys and 1246 girls) aged 7-18 years using standard adjustable Jamar hydraulic hand dynamometer and pinch gauge. A set of 17 hand-forearm anthropometric dimensions were also measured with an accurate digital caliper and tape measure. RESULTS: No significant differences were found between the hand strengths of boys and girls up to the age of 10 years. Gender related differences in handgrip and pinches were observed from the age of 11 years onwards, with boys always being stronger. The dominant hand was stronger than the non-dominant hand (8% for handgrip and by about 10% for all three types of pinches). The strongest correlations were found between the hand length and hand strengths (r > 0.83 for handgrip and three all pinches; p < 0.001, 2-tailed). Based on the partial least squares (PLS) analysis, 8 out of 17 anthropometric indices including hand length, hand circumference, thumb length, index finger length, middle finger length, and forearm length had considerable loadings in the PLS analysis, which together accounted for 46% of the total variance. CONCLUSIONS: These results may be used by health professionals in clinical settings as well as by designers to create ergonomic hand tools.

Application of the theory of planned behavior in the design and implementation of a behavior-based safety plan in the workplace.

BACKGROUND: Many accidents in industries occur due to unsafe practices and unsafe conditions. Occupational accidents endanger the health of workers and impose excessive costs on the employers. This study was designed and conducted to evaluate and implement a behavior-based safety approach in an industrial workplace based on the theory of planned behavior. MATERIALS AND METHODS: The present study was a quasi-experimental study performed on 90 supervisors of an industrial workplace. Behavior-based safety interventions were performed based on the components of the theory of planned behavior using nine strategies of health education and health promotion, including skills training, participation, and social support. The data collection tool consisted of a researcher-made questionnaire that was answered by the supervisors before and 6 months after the intervention. The collected data were evaluated using SPSS 22 software. The significance level was considered 0.05. RESULTS: The results showed that the constructs of subjective norms, attitude, and perceived control of behavior predict the safe behavior of supervisors. After behavior-based safety interventions, significant changes were observed in subjective norms, intention, attitude, and perceived control of behavior (P < 0.001) compared to before the intervention. CONCLUSION: The results of this study showed the improvement of safe behavior of supervisors in the workplace due to behavioral-based safety interventions using the theory of planned behavior. Accordingly, this theory can be used as a suitable theoretical framework for designing and implementing interventions to promote safe behaviors of employees in the workplace.

Maximum handgrip strength as a function of type of work and hand-forearm dimensions.

BACKGROUND: Handgrip strength is a measurement of upper extremity functionality and an indicator of overall physical ability. OBJECTIVES: The objective of this study was to compare maximum handgrip strength (MGS) between manual workers and office employees and to investigate if the expected difference is related to the anthropometric dimensions of the workers' hands and forearms. METHODS: This was a cross-sectional study with a sample of 1740 male workers (905 light manual workers; and 835 office employees), aged 20-64 years. Maximum voluntary contractions were obtained using a JAMAR dynamometer according to the methodology proposed by the American Society of Hand Therapy (ASHT). The highest value obtained from three trials was considered as the MGS for each side. Six anthropometric dimensions (i.e., hand length, palm length, forearm length, hand breadth, wrist circumference and forearm circumference) were measured by digital caliper and tape measure. RESULTS: Maximum handgrip strength of light manual workers (52.7±8.5 kg) was significantly higher than that of office employees (47.3±8.4 kg) (p < 0.001). Maximum handgrip strength was positively correlated with Hand breadth (r = 0.781 for light manual workers and r = 0.766 for office employees; p < 0.001) and Forearm circumference (r = 0.741 for light manual workers and r = 0.752 for office employees; p < 0.001); the only dimensions which were significantly different between the two studied job groups. CONCLUSIONS: The results of this study revealed that light manual workers are approximately 12.4% stronger than office employees in terms of maximum handgrip force. It is therefore imperative to consider the observed differences in clinical, workstations, and hand tool designs in order to increase efficiency and comfort at work.

Normative hand grip strength and prediction models for Iranian office employees.

BACKGROUND: Normative data on Hand grip strength has a wide range of application and is of great value. OBJECTIVE: To establish gender and age-specific reference data concerning hand grip strength of Iranian office workers, to explore possible relationships with demographic and anthropometric factors and to develop appropriate predictive models. METHODS: The study population included 418 (220 males and 198 females) Iranian office employees. They were divided into 5-year age-groups. Hand length, palm width, palm length, forearm length, wrist circumference, and forearm circumference were measured by means of a digital Caliper (±0.01 mm) and a tape meter (±0.1 cm). The value of hand grip strength was measured by JAMAR hydraulic dynamometer respecting the American Society of Hand Therapy recommendations. RESULTS: The average of grip strength for dominant and non-dominant hands (in Kg) respectively was 51.10±9.50 and 46.90±9.89 for male and 28.76±4.47 and 25.89±4.60 for female. Age was curvilinearly related to hand grip strength. All selected hand dimensions were highly correlated with grip strength; palm width, palm length and hand length being the most correlated ones, respectively. Prediction equations of hand grip strength were developed for dominant and non-dominant hands of both genders. CONCLUSIONS: Suggested norms would provide more accuracy for ergonomic designers as well as health practitioners especially with regards to proposed prediction models with which grip strength could be estimated faster and easier.