Physical exertion and working efficiency of reforestation workers

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 HR(max), and maintain HR at approximately 59% of HR(max )throughout the entire working day. Productivity in these workers appears to be related to effort rather than to experience or task efficiency per se.