Purpose: Collecting waste is regarded as a benchmark for "particularly heavy" work. This study aims to determine and compare the workload of refuse workers. We examined the equivalence between heart rate and oxygen uptake at work as physiological parameters of workload.
Methods: 65 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 stationary cardiopulmonary exercise testing (CPX). Heart rate at work (HR) was recorded by a pulse belt. Oxygen uptake at work for one hour (VO2,1h) was recorded with a portable spiroergometry system.
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)). At work mean VO2,1h was 1,103 (SD 237) ml/min, mean HR over the whole shift (HRsh) was 100.2 (SD 11.9) b/min. Compared to reference limits for heavy work, 41% of the total sample had shift values above 30% of their heart rate reserve (HRR); 34% of the individuals had mean HRsh values above the HR corresponding to 30% of individual maximum oxygen uptake (VO2,max). All individuals had mean VO2,1h above 30% of VO2,max.
Conclusion: HR as well as VO2 can be valuable indicators for investigating physiological workload during work. In terms of absolute and relative heart rate and oxygen consumption, employment as a refuse collector should be classified in the upper range of defined heavy work. The definition of heavy work as above 30% of continuous performance with respect to the personal maximum performance should be reviewed and possibly revised upwards.