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.

Safety Evaluation of the Lighting at the Entrance of a Very Long Road Tunnel: A Case Study in Ilam

BACKGROUND: At the entrance of a tunnel, reflection of sunlight from the surrounding environment and a lack of adequate lighting usually cause some vision problems. The purpose of this study was to perform a safety evaluation of lighting on a very long road in Ilam, Iran. METHODS: The average luminance was measured using a luminance meter (model S3; Hagner, Solna, Sweden). A camera (model 108, 35-mm single-lens reflex; Yashica, Nagano, Japan) was used to take photographs of the safe stopping distance from the tunnel entrance. Equivalent luminance was determined according to the Holliday polar diagram. RESULTS: Considering the average luminance at the tunnel entrance (116.7 cd/m²) and using Adrian's equation, the safe level of lighting at the entrance of the tunnel was determined to be 0.7. CONCLUSION: A comparison between the results of the safe levels of lighting at the entrance of the tunnel and the De Boer scale showed that the phenomenon of black holes is created at the tunnel entrance. This may lead to a misadaptation of the drivers’ eyes to the change in luminance level at the entrance of the tunnel, thereby increasing the risk of road accidents in this zone.