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Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Physical exertion and working efficiency of reforestation workers | Hodges and Kennedy Journal of Occupational Medicine and Toxicology 2011 6 20 http www.occup-med.eom content 6 1 20 _ JOURNAL OF OCCUPATIONAL MEDICINE AND TOXICOLOGY RESEARCH Open Access Physical exertion and working efficiency of reforestation workers Alastair NH Hodges and Michael D Kennedy Abstract Background The purpose of this study was to quantify the physical exertion during tree planting work and to examine the relationships between exertion task efficiency and productivity. Methods Heart rate HR was monitored on 34 tree planters while they worked. HR data was collected for a complete working day on 19 subjects and for shorter periods of time on 15 subjects. Video of work tasks was recorded on 22 subjects video was recorded on 7 of the subjects for whom HR was monitored through a full working day and analyzed for working pace and proportion of time spent on each task. Results HR during a full day 9.0 1.2 hours of tree planting work was 115.2 8.8 beats.min-1 and working HR was 128.2 15.6 beats.min-1 for 82.5 6.8 of the work day. Mean work pace was 452 174 trees.h-1 and the proportion of time spent planting each tree was 53 8 of the working time. Significant P 0.05 positive correlations were found between work pace and experience level and between work pace and working HR and a significant P 0.05 negative correlation was found between experience level and HR for a given work pace. No significant relationships were found between experience level or work pace and the proportion of time spent planting each tree. Conclusions Tree planters work at approximately 65 of age-predicted HRmax and maintain HR at approximately 59 of HRmax throughout the entire working day. Productivity in these workers appears to be related to effort rather than to experience or task efficiency per se. Background Harvesting of Canada s forests which cover almost 250 million hectares of land and account for 27 of the country s land mass 1 is an important industry and vital part of the .