Measured by the oxygen uptake in the field, the work of refuse collectors is particularly hard work: Are the limit values for physical endurance workload too low?

Purpose: Collecting waste is regarded as a benchmark for "particularly heavy" work. This study aims to determine and compare the workload of refuse workers in the field. We examined heart rate (HR) and oxygen uptake as parameters of workload during their daily work.
Methods: Sixty-five refuse collectors from three task-specific groups (residual and organic waste collection, and street sweeping) of the municipal sanitation department in Hamburg, Germany, were included. Performance was determined by cardiopulmonary exercise testing (CPX) under laboratory conditions. Additionally, the oxygen uptake (VO2) and HR under field conditions (1-h morning shift) were recorded with a portable spiroergometry system and a pulse belt.
Results: There was a substantial correlation of both absolute HR and VO2 during CPX [HR/VO2 R 0.89 (SD 0.07)] as well as during field measurement [R 0.78 (0.19)]. Compared to reference limits for heavy work, 44% of the total sample had shift values above 30% heart rate reserve (HRR); 34% of the individuals had mean HR during work (HRsh) values that were above the HR corresponding to 30% of individual maximum oxygen uptake (VO2,max). All individuals had a mean oxygen uptake (VO2,1h) above 30% of VO2,max.
Conclusion: HR as well as the measurement of VO2 can be valuable tools for investigating physiological workload, not only under laboratory conditions but also under normal working conditions in the field. Both in terms of absolute and relative HR and oxygen consumption, employment as a refuse collector should be classified in the upper range of defined heavy work. The limit of heavy work at about 33% of the individual maximum load at continuous work should be reviewed.