Determination of Work-Rest Schedules Based on Physical Workload Among Bakers in Ahvaz, Iran

Abstract

Background: Bakery workers due to exposure to radiant heat and doing manual labor are at risk of heat-related illnesses and musculoskeletal disorders Objectives: The current study aimed to determine the appropriate work-rest time interval using two indexes of wet bulb globe temperature (WBGT) and relative heart rate (RHR). Methods: It was an analytical and descriptive research. Heart rate of workers was continuously recorded to achieve the physiological monitoring and the obtained information was used to determine the work difficulty and physical workload. The ratio of heat stress and RHR was measured using the WBGT and polar team pro device, respectively. Work-rest schedules were detected through the heart rate reserve and heat stress indexes. The level of significance was α = 0.05. Results: Physical workload based on heart rate was estimated light to moderate in bakery workers. Suitable work-rest schedule for all bakery workers according to WBGT index was 25% work-75% rest and based on heart rate reserve index in half of the workers was 50% work-50% rest, and in the other half of the bakery workers was continuous work without rest. According to Kappa test, there was no agreement between the two methods of heat stress index and heart rate reserve to determine the work-rest schedules of workers (P < 0.001). Conclusions: Physical workloads on the basis of heart rate were light for all workers except the workers of Tanoury who had moderate workload. Meanwhile, determining the work-rest schedule was different using the two indexes. The heart rate reserve index represents the physiological status of individual during the work and states the ratio of physical workload more precisely.